METHOD AND DEVICE FOR MEASURING DIMENSIONS BY X-RAYS, ON EMPTY GLASS CONTAINERS RUNNING IN LINE

The present invention relates to the technical field of the inspection of empty glass containers, such as, for example, bottles, jars, flasks with a view to detecting possible dimensional defects.

The present invention relates more specifically to the measurement of dimensions on empty glass containers, scrolling in line after their manufacture in order to determine whether such containers meet the required dimensional criteria.

After their manufacture, empty glass containers are subjected to various dimensional checks.

Thus, it is known that there is a risk that the containers have one or more localized areas of poor distribution of glass affecting the aesthetics or more seriously, the mechanical strength of the containers.

To measure the thickness of the wall of a container, it is known, for example, from patent EP 0 320 139 or patent EP 0584 673, a method known as by triangulation consisting in projecting a light beam on the wall of the container with a non-zero angle of incidence, and to collect the light beams reflected from the outer surface and the inner surface of the wall. These light reflections on these two surfaces take place in the specular directions of the incident beams, that is to say symmetrically to the incident beam with respect to the normal to the surface at the point of impact of the incident beam. The rays reflected from the interior and exterior surfaces of the wall are collected by a lens in order to be sent to a linear light sensor. The Wall thickness of the container is measured as a function of the separation, at the light sensor, between the beams reflected from the inner and outer surfaces of the wall. The container is rotated in a revolution to measure its thickness according to one of its cross sections.

An alternative to the previous technique of optical measurement by triangulation is measurement by the so-called “confocal optical” method.

chromatism ”as described by application DE 10 2007 044 530. This method consists in sending a light beam having chromatic coding, in recovering the beams reflected by the inner and outer faces, on a sensor making it possible to analyze the length of wave of said reflected beams, and in determining the thickness as a function of the wavelengths of said reflected beams.

Likewise, patent EP 2 676 127 describes a device enabling the thickness of the glass wall of containers to be measured at several measuring points distributed over an inspection region in a superimposed manner according to a determined height of the container taken according to the central axis. The inspection method aims to detect material distribution defects in transparent containers having a central axis and a wall delimited between an outer face and an inner face.

The optical measurements described above are widely used because they are contactless and fairly rapid, but they all require the containers to be set in rotation to measure the thickness on a circumference. Indeed, these techniques have in common the projection of a beam of light and the recovery of the light reflected by the two interior and exterior surfaces of the wall. Only certain incidences and corresponding directions of observation are then possible, in particular due to specular reflection. Since the containers are generally cylindrical, measurement is only possible for a narrow region located around the optical axis of the sensors. It is therefore not possible to

Additionally, the rotation of the containers required for the optical thickness measurement is expensive. Indeed, the rotation requires the use of complex handling equipment. It is in fact necessary to stop the containers which arrive in translation on the conveyor, to drive them in rotation during the measurement and to put them back in translational movement on the conveyor. The receptacles are then placed in contact with guides, rollers, stars. The settings are tedious and involvethe use of equipment adapted to each container format (variable equipment). Finally, production rates are limited to 300-400 containers per minute, whereas the current production of glass containers on the most efficient lines currently exceeds 700 containers per minute. In some cases, therefore, dual measuring equipment is required.

Conventionally, empty glass containers are also subject, apart from the thickness measurements of their wall, to measurements at the level of the neck or the ring of the container (internal / external diameters, tightness, height) and of the neck. of the container (internal diameter, internal profile, pinout).

In order to carry out such inspections, it is known to use one or more devices each comprising an inspection head intended to be lowered either over a precise distance depending on the nature of the container, or to come into contact with the container, or to be resting on the container during the inspection. Conventionally, such an inspection is carried out using a machine having either a linear conveyor adapted to maintain the containers in precise positions, or preferably a star conveyor, with an indexed circular movement to place the containers in position. relationship with different checkpoints. Each inspection head is moved in a reciprocating vertical motion for a star conveyor while for a linear conveyor, the head of

Patent FR 2 818 748 describes an inspection device comprising a head mounted on a horizontal slide which is fixed to a carriage moved in vertical reciprocating movements by a belt mounted between a mad pulley and a pulley driven by a servomotor. One of the drawbacks of such a device is the relatively large displaced mass, which limits the speed and acceleration of movement of the inspection head. As a result, the inspection rate of the containers is limited, which is a major drawback in the on-line container production process. Another drawback of such a known device appears when the inspection head is intended to come into contact with thecontainer. Indeed, the stroke of the inspection head is not defined because of the height dispersion of the containers and the defects which influence this stroke such as those which do not allow the inspection head to descend during a broaching operation. Also, taking into account the indeterminacy of this stroke and of the on-board mass, a significant impact may occur between the inspection head and the container, which is liable to cause deterioration of the container and / or of the head. inspection.

Patent GB 1 432 120 describes a device for inspecting containers comprising several control stations, one of which aims to check the dimensional conformity of the rings and the necks of the containers. This control station comprises a mobile unit driven by a motorization system according to a reciprocating movement with respect to the frame of the device, in a direction of movement parallel to the axis of symmetry of the containers. This mobile unit is equipped with an external gauge for checking the outside of the ring of the receptacles and with an internal gauge for checking the inside of the ring and the neck of the receptacles. The device described by this document GB 1 432 120 has the same drawbacks as the inspection device described by patent FR 2 818 748.

The patent FR 2 965 344 by lightening the moving part, by combining contact detection and dynamic control of vertical movement, makes the solution significantly faster, but nevertheless the mechanical movements of handling containers, variable equipment and contact of gauges with the containers remain major drawbacks.

In the field of detecting a volume of liquid contained in a container, patent application WO 2010/025539 describes an X-ray inspection system and method. The principle of detection of this document is to know the thickness of liquid traversed from the x-ray image (reference 512 in Fig. 5a and 592 in Fig. 5b) in order to deduce the filling level (meniscus 520) and therefore the total volume of liquid at the inside the container. For this purpose, the method proposes to subtractof the radiographic image, the attenuation due to the glass thicknesses passed through 508 and 506.

However, it is not possible in the radiography projected in direction 502-504 to know the attenuation due to the glass and that due to the liquid contained. To remedy this problem, this document proposes to create a theoretical three-dimensional model of the container from its two-dimensional radiographic image. From the radiographic image, the attenuation of the three-dimensional theoretical model of the container is subtracted in order to deduce the measured attenuations, only the attenuations of the liquid making it possible to approximately deduce the volume of liquid therefrom.

According to the exemplary embodiment described by this document, the theoretical three-dimensional model is obtained from an X-ray taken in a single direction of projection. The radiography is analyzed to know the two-dimensional profile of the projected container in a projection direction. The two-dimensional profile of the container is used to obtain the theoretical three-dimensional shape of the container either from a library of recorded models or by revolution of the two-dimensional profile taking into account the assumed form of axial symmetry of the containers.

According to another exemplary embodiment, this document suggests taking radiographic images in different directions in order to improve the precision of the determination of the position of the meniscus of the liquid. According to this example, the method aims to determine the position of the meniscus of the liquid according to a first radiographic direction, the position of the meniscus of the liquid according to a second radiographic direction and to retain the position of the meniscus of the liquid for the mean position of the meniscus of the liquid.

Whatever the exemplary embodiment, the three-dimensional theoretical model constructed according to the teaching of this document does not correspond to the real container which is the subject of the radiography. Measurements in particular of thicknesses carried out on such a three-dimensional theoretical model are therefore false. In addition, it should be noted that the only possibly possible thickness measurements are those in a directionorthogonal to the direction of radiographic projection. Thus, the dimensions such as the thickness of the glass in the directions not orthogonal to the direction of radiographic projection are exactly the same as the thicknesses in the two-dimensional profile, therefore in the directions orthogonal to the radiographic projections. This assumption which is verified only for a perfect or theoretical container as assumed in this document, is of course false for a container on which precise measurements are to be carried out.

Patent application JP S60 260807 proposes measuring the thickness of the walls of a tube moving in translation along the axis of the tube, using X-ray measurements from one or more foci at each of which sensors are associated. The foci and the sensors are positioned to produce radiographic projections in a plane orthogonal to the direction of movement of the tube. The radiographic projections are therefore copianary in a projection plan which is orthogonal to the axis of symmetry of the tube. The direction of these radiographic projections makes a right angle (90 °) to the direction of travel. This technique does not allow complete knowledge of the internal and external surfaces of the tube. The method described by this patent application makes it possible to measure only the

Likewise, US Pat. No. 5,864,600 describes a method for determining the filling level of a container using an X-ray source and a sensor arranged transversely on either side of the transport conveyor. containers. This method makes it possible to measure the cumulative thickness of the material. This system does not make it possible to carry out measurements for a non-transversely oriented surface because this document does not provide for three-dimensional modeling of the containers.

Patent application US 2009/0262891 describes a system for detecting by X-rays, objects placed in baggage moved in translation by a conveyor. This system includes generator tubes

pulsed or a sensor having a large dimension parallel to the direction of travel. This document provides a method of reconstructing the object which is not satisfactory because the absence of projections in the direction of displacement does not allow the measurement of dimensions in the direction orthogonal to the direction of displacement. The lack of radiographic projections in an angular sector does not make it possible to produce a digital model suitable for ensuring precise measurements.

Patent application DE 197 56 697 describes a device exhibiting the same drawbacks as patent application US 2009/0262891.

Patent application WO 2010/092368 describes a device for viewing an object moving in translation by X-rays using a radiation source and three linear sensors.

Patent application US 2006/0058974 describes a digital radiography imaging system making it possible to acquire digital images in particular of reservoirs or pipes and to transform these digital images into a map of absolute thickness characterizing the inspected object. The digital data generated from each sensitive element is calibrated, for example, by correcting for variations in X-ray paths between the X-ray source and the detector, correcting for variations in the spatial frequency response, correcting for variations geometrical profile of the object under inspection and correcting the material contained in and / or around the object. This technique cannot be implemented for the dimensional inspection of containers moving in line.

Analysis of the prior technical solutions shows that there appears to be a need for a new technique making it possible to carry out dimensional measurements on containers without ventilating their integrity while maintaining a high speed of conveying to these containers.

The present invention aims to satisfy this need by proposing a new non-contact measurement technique making it possible to carry out precise dimensional measurements on containers moving in line at high speed.

To achieve this objective, the object of the invention relates to a method for measuring the dimensions of at least one region to be inspected of empty glass containers of a series each having a wall forming a neck and a body and delimited by a internal surface and an external surface, the process consists of:

- choosing at least one region to be inspected comprising at least part of the neck and / or part of the body of the container;

transporting the containers placed on their bottom in a conveying plane along a flat path with a direction materialized by a displacement vector, these containers generating a conveying volume during their displacement;

- Positioning, on either side of the region to be inspected, at least one focal point of an X-ray generator tube and image sensors sensitive to X-rays and each exposed to X-rays from an associated focal point, these X-rays having passed through at least the region to be inspected, producing on each image sensor a radiographic projection in the direction of projection;

- acquire using image sensors for each container during its movement, at least three radiographic images of the inspected region, obtained from at least three radiographic projections of the region to be inspected, the projection directions of which are different ;

- construct using a computer system, a digital geometric model of the region inspected for each container, from at least three radiographic images, the digital geometric model of the region to be inspected containing the three-dimensional coordinates of a set of points, calculated from at least three radiographic images, this set of points belonging to the internal and / or external surface of the wall of the container, with at least two points situated in a plane not orthogonal to a direction of projection;

- deduce at least one internal diameter of the neck measured on the digital geometric model in a plane not orthogonal to a direction of projection, and / or at least one thickness of the body wall measured on the digital geometric model in a plane not orthogonal to a direction of projection.

In addition, the method according to the invention may further comprise in combination at least one and / or the other of the following additional characteristics:

- the digital geometric model of the region to be inspected containing the three-dimensional coordinates of a set of points is made up of:

• at least two three-dimensional points of space each belonging to an internal and / or external surface of the wall of the container and located in a plane not orthogonal to a direction of projection, and not parallel to the direction of displacement;

• and / or at least one surface representation of the internal and external surfaces of the wall of the container containing points not belonging to a plane orthogonal to a direction of projection, and not belonging to a plane parallel to the direction of displacement ;

• and / or at least one section of the region to be inspected, according to a plan different from a plane orthogonal to a direction of projection and different from a plane parallel to the direction of displacement;

the method consists in choosing as the region to be inspected at least one defined zone extending between two planes parallel to the conveying plane;

- the method consists in choosing as the region to be inspected, an area comprising the neck and a body part of the container and in determining a digital geometric model of the region to be inspected containing the three-dimensional coordinates of a set of points belonging to the internal surfaces and outside of the wall of the container in the inspected region, to derive at least an inside diameter of the neck and a thickness of the glass wall of the body of the container;

- the method consists in positioning on one side of the trajectory, a focus from which a diverging X-ray beam of aperture> 120 ° or at at least two foci from which divergent X-ray beams emerge, the sum of the apertures of which is greater than or equal to 120 °;

- The method consists in placing at least one hearth in the conveying plane;

- the method consists in having on one side of a secant plane of the conveying volume, orthogonal to the conveying plane, a focus from which a divergent X-ray beam emanates, so that its beam crosses the secant plane and the region to inspect;

the method consists in placing on the opposite side with respect to the secant plane, at least one image sensor associated with said focal point to receive the X-rays coming from said focal point;

- The method consists in having on one side of the conveying plane, a focus from which a divergent X-ray beam emanates, so that its beam passes through the conveying plane;

- The method consists in placing on the opposite side with respect to the conveying plane, at least one image sensor associated with said focus to receive the X-rays coming from said focus;

- the method consists in acquiring using image sensors, for each container during its movement, at least two radiographic images of the inspected region corresponding to projection directions defining a useful angle greater than or equal to 45 ° and less than or equal to 90 ° and, advantageously greater than or equal to 60 ° and less than or equal to 90 °;

- The method consists in acquiring with the aid of the image sensors, for each container during its movement, at least one radiographic image of the inspected region corresponding to a direction of projection having an opening angle with the direction of displacement between 10 ° and 60 °;

- the method consists in making and acquiring radiographic projections of the inspected region of a container so that the X-rays coming from the focal point (s) and reaching the image sensors do not pass through other containers;

- The method consists in acquiring with the aid of image sensors, for each container during its movement, radiographic images from between three and forty, and preferably between four and fifteen radiographic projections of the region to inspect from different directions;

- the image sensors are of the linear type each comprising a linear array of elements sensitive to X-rays, distributed along a support line defining with the associated focus, a projection plane containing the direction of projection, these image sensors being arranged so that:

• at least m sensitive elements of each of these image sensors receive the radiographic projection of the region to be inspected by the X-ray beam coming from the associated focus;

• the projection planes for the different image sensors are distinct from one another and not parallel to the conveying plane;

• using each of the at least three linear image sensors is acquired, at each incremental displacement of each container along the trajectory, radiographic linear images of the region to be inspected according to a number chosen so that for each container, l the entire region to be inspected is shown completely in the set of linear radiographic images;

• the at least three sets of x-ray linear images of the region to be inspected are analyzed for each container;

- the method consists in making available to the computer system, an a priori geometric model of the region to be inspected of the series of receptacles, obtained by:

• the digital computer design model of the series containers;

• or the geometric digital model obtained from the measurement of one or more receptacles of the same series by a measuring device;

• or the geometric digital model generated by the computer system from values ​​entered and / or drawings produced and / or shapes selected by an operator on a man-machine interface of the computer system;

the method consists in making the value of the attenuation coefficient of the glass constituting the containers available to the computer system.

Another object of the invention is to provide an installation for automatic measurement of linear dimensions of at least one region to be inspected of empty glass containers each having a wall forming a neck and a body and delimited by an internal surface and a surface. external, the installation comprising:

a device for transporting the containers in a direction materialized by a displacement vector, along a substantially rectilinear path in a conveying plane, the containers traveling through an extended conveying volume in the direction;

- at least one focus of an X-ray generator tube located outside the volume crossed, and creating a divergent beam of X-rays directed to pass through at least one region to be inspected comprising at least part of the neck and / or part of the container body;

- at least three image sensors, located outside the conveying volume, so as to receive X-rays coming from an associated focus, the focus (s) and the image sensors being arranged so that each sensor of images receive the radiographic projection of the region to be inspected by the rays coming from the focal point when the container passes through these rays, the directions of projection of these radiographic projections being different from one another;

- an acquisition system connected to the image sensors, so as to acquire for each container during its movement, at least three radiographic images of the region to be inspected, obtained from at least three radiographic projections of the region to be inspected , with different directions of projection;

- and a computer system analyzing the at least three radiographic images, originating from at least the three different radiographic projections, so as to construct for each container, a digital geometric model of the region to be inspected, said digital geometric model containing the three-dimensional coordinates a set of points, calculated from the at least three radiographic images, this set of points belonging to the internal and / or external surface of the wall of the container, with at least two points located in a plane not orthogonal to a direction projection, each digital geometric model making it possible to deduce at least one internal diameter of the neck measured on the model in a plane not orthogonal to a direction of projection,and / or at least one thickness of the body wall measured on the model in a plane not orthogonal to a direction of projection.

In addition, the installation according to the invention may further include in combination at least one and / or the other of the following additional characteristics:

- at least two X-ray production foci, positioned separately in two distinct positions and at least three image sensors, sensitive to X-rays and positioned so that:

• each focus emits its beam through at least the region to be inspected in order to reach at least one associated image sensor;

• each image sensor is associated with a focal point and receives the X-rays coming from said focal point after having crossed the region to be inspected;

at least one focal point from which a divergent X-ray beam emanates with an aperture greater than or equal to 120 ° or at least two focal points from which emanate beams of divergent X-rays, the sum of the apertures of which is greater than or equal to 120 °;

- at least one hearth arranged in the conveying plane;

on one side of a plane secant to the conveying volume and orthogonal to the conveying plane, a focus from which a divergent X-ray beam emanates, so that its beam crosses the secant plane and the region to be inspected;

- on the opposite side with respect to the secant yaw, at least one image sensor associated with said focal point for receiving the X-rays coming from said focal point;

on one side of the conveying plane, a focus from which a divergent X-ray beam emerges, so that its beam passes through the conveying plane;

- on the opposite side with respect to the conveying plane, at least one image sensor associated with said focal point for receiving the X-rays coming from said focal point;

at least one focus and two image sensors are arranged so that the directions of projection of the inspected region that they receive have between them a useful angle greater than or equal to 45 ° and less than or equal to 90 ° and, advantageously greater than or equal to 60 ° and less than or equal to 90 °;

- at least one focus and one image sensor are arranged so that, when a container passes through the field of the image sensors, the direction of projection of the region inspected on the image sensor makes an opening angle with the direction of movement between 10 ° and 60 °;

- the image sensors and the focal points are arranged so that the X-rays emanating from the focal point (s) and reaching the image sensors and passing through the region of one container do not pass through other containers at the same time;

- between one and four foci, resulting from one or more tubes generating X-rays;

the number and arrangement of the image sensors and associated foci are such that for each container during its movement, the radiographic projections of the region to be inspected on the image sensors present between three and forty, and preferably between four and fifteen different directions of projection;

- the image sensors are of the linear type and each comprise a linear array of elements sensitive to X-rays, distributed along a support line defining with the associated focus, a projection plane containing direction of projection, these image sensors being arranged so that:

• at least m sensitive elements of each of these image sensors receive the radiographic projection of the region to be inspected by the X-ray beam coming from the associated focus;

• the projection planes for the different image sensors are distinct from one another and not parallel to the conveying plane;

at least three linear image sensors have their support lines parallel to each other;

- at least three linear image sensors have their support lines orthogonal to the conveying plane;

- a focus is positioned on one side of the conveying plane, and according to the invention at least one associated linear image sensor is positioned on the side opposite the focus with respect to the conveying plane and so that its straight support is parallel to the conveyor plane;

According to the invention, the installation comprises:

- a device for making available to the computer system, the attenuation coefficient of the glass constituting the receptacles;

a device for making available to the computer system, an a priori geometric model of the region to be inspected which is a mass memory, a wired or wireless computer network or a man-machine interface;

- a device for making available to the computer system, values ​​and / or tolerances for the dimensions of the neck and / or minimum value of glass thickness for the body wall, and / or at least one model geometric reference of a container.

Various other characteristics emerge from the description given below with reference to the appended drawings which show, by way of non-limiting examples, embodiments of the object of the invention.

Figure 1 is a schematic top view showing an installation allowing the measurement by X-rays of dimensions on containers moving in line.

Figure 2 is a schematic side perspective view showing an installation for measuring by X-rays, dimensions on a container.

Figure 3 is a schematic sectional view showing part of an inspected container.

Figure 4 is a schematic perspective view showing the volume traversed or generated by the containers during their linear movement.

FIG. 5 is a schematic top view showing an exemplary embodiment of an installation according to the invention comprising three focal points generating X-rays.

Figure 6 is a schematic cross-sectional elevational view of the installation illustrated in FIG. 5.

Figure 7 is a schematic side elevational view of the installation illustrated in FIG. 5.

Figures 8 and 9 are schematic views explaining the definition of the useful angle between two directions of projection.

Figures 10 and 11 are schematic perspective views showing the positioning of image sensors with respect to the movement of the containers to be inspected.

Figure 12 is a view of an exemplary embodiment of an installation according to the invention implementing matrix image sensors.

Figure 13 is a view of a matrix of elements sensitive to X-rays on which appears two distinct zones corresponding to two sensors of matrix images.

Figure 14 is a view of a digital geometric model of a container obtained according to the method according to the invention, when the inspection region comprises the neck

Figure 15 shows a vertical section and four horizontal sections of the digital geometric model of a container obtained according to the method according to the invention and on which measurements of dimensions are represented.

As a preliminary, some definitions of the terms used in the context of the invention are given below.

A focus Fj of an X-ray generator tube is a point X-ray source, preferably a “micro focus”, with a diameter for example between 0.01 mm and 1 mm, creating a divergent beam of X-rays. '' use any type of point or near point X-ray source.

A sensitive element is an element sensitive to X-rays, in other words an elementary surface, of dimension for example 0.2 x 0.2 mm or 0.02 x 0.02 mm, converting the X-rays that it receives into a signal Electrical, Usually, a scintillator converts x-rays into visible light and then a photoelectric sensor converts visible light into an electrical signal. Techniques for the direct conversion of X-rays into electrical signal also exist. A pixel designates an elementary value of a point of a sampled image, characterized by its gray level between 0 and a maximum value. For example for a 12-bit digital image, a pixel takes digital values ​​between 0 and 4095.

A radiographic image reading or acquisition system comprises one or more surfaces sensitive to X-rays, that is to say surfaces comprising sensitive elements converting the X-rays into an electrical signal to be transmitted to an X-ray system. analysis conventionally implemented by a computer and referred to as a computer system in the remainder of the description. The signals originating from a set of sensitive elements belonging to a same sensitive surface area, acquired by the acquisition device and transmitted together to the computer system, constitute a radiographic image. To be analyzed by the computer system, the radiographic images are preferably converted into digital radiographic images either as close as possible to the sensitive surface,

The X-ray beams from a focus Fj pass through at least one inspected region, and form on a sensitive surface, the radiographic projection of the inspected region, which is sometimes called the radiant image. and which contains the information on the attenuation of the X-rays by the material passed through.

An X-ray sensitive surface area which receives the radiographic projection of the inspected region is called image sensor Cji. An image sensor Cji is exposed to X-rays from an associated focus Fj. The image sensor converts this X-ray projection into an X-ray image of the inspected region. When the sensitive surface area contains a line of photosensitive elements, the transmitted radiographic image is linear, composed of a line of pixels forming an array of one-dimensional values. When the sensitive surface area contains a matrix of photosensitive elements, the transmitted radiographic image is a matrix, composed of a matrix of pixels forming an array of two-dimensional values.

The direction of projection Dji is the oriented direction or the vector starting from the focus Fj to pass through the center of the image sensor Cji, that is to say through the center of an X-ray sensitive area which receives the projection X-ray image of the region inspected at the time of acquisition during movement of the vessel between the focus and the image sensor. For an associated image sensor-focus pair, the projection direction is the vector from the focus reaching the middle of the image sensor. The positioning of the image sensors is such that the sensitive surface is not parallel to the direction of projection. It may be advantageous in certain cases for the sensitive surface of the image sensor to be orthogonal to the direction of projection defined with the associated focus. But it doesn't

The directions of projection Dji of radiographic projections are different if the directions of projection Dji taken in pairs form a minimum angle of at least 5 ° between them.

A sensitive surface area containing a single Sign of sensitive elements constitutes a linear image sensor, which comprises an array linear of sensitive elements, distributed along a support line segment. According to this definition, a column or a row belonging to a sensitive matrix surface, acquired and transmitted separately by the acquisition device is considered to be a linear image sensor. Several sensitive surface areas of the same surface and each containing a single row of different pixels therefore constitute several linear image sensors. The direction of projection associated with the linear radiographic image obtained is therefore the direction starting from the focus and passing through the middle of the support line segment at the moment of acquisition of the image.

A sensitive surface area which contains an array of sensitive elements constitutes a matrix image sensor, which comprises a matrix array of X-ray sensitive elements, distributed in a matrix. As shown in Fig. 12, according to this definition, an area of ​​matrix sensitive surface C11, C12, which belongs to a larger sensitive surface Ss, and which is acquired and transmitted separately by the acquisition device, is a matrix image sensor. Several matrix sensitive surface areas C11, C12 of the same surface, acquired and transmitted separately by the acquisition device therefore constitute several matrix image sensors supplying different radiographic images respectively M11, M12 (FIG. 13). The DU direction, Projection D12 associated with the matrix radiographic image respectively M11, M12 is the direction starting from the focus F1 and passing through the middle of the zone C11, C12 of the matrix sensitive surface, at the instant of acquisition of the image. It is therefore possible that the image sensors C11, C12 are non-disjoint regions activated successively in time.

Of course, the person skilled in the art can use matrix sensor technology based on an image intensifier or else a “screen capture camera” in which a scintillator plate receives the radiant image, converts it into visible light, the visible image at the rear of the scintillator being photographed by a visible camera fitted, if necessary, with an objective.

As emerges from the Figures, the object of the invention relates to an installation 1 allowing the implementation of a method for carrying out measurements of dimensions on empty glass containers 2. Conventionally, a container 2 is a. hollow object comprising a bottom 3 connected to a heel or rim from which rises a body 4 extending by a shoulder connected to a neck or neck 5 terminated by a ring 6 delimiting the mouth allowing the container to be filled or emptied . Thus as illustrated in FIG. 3, a container 2 has a glass wall 7 delimited internally by an internal surface 8 and externally by an external surface 9. The wall 7 has between the internal surface 8 and the external surface 9 a thickness e.

According to an advantageous embodiment characteristic, at least one region of the container is chosen to be inspected so as to be able to carry out measurements of dimensions in this region of the container, corresponding to a dimensional characteristic of the region to be inspected. Typically, the region to be inspected may comprise at least the neck 5 of the container and the measurement of a dimensional characteristic of this region to be inspected corresponds at least to the internal diameter D of the neck. Similarly, the region to be inspected may comprise at least a portion of the wall of the body 4 between the rim and the shoulder and delimited for example by two planes parallel to the laying plane of the container, and the measurement of a dimensional characteristic of this region to be inspected corresponds to the thickness e of the glass wall between the internal 8 and external 9 surfaces delimiting this wall 7. The invention is therefore very particularly suitable for measuring dimensions in relation to the internal surface of the wall at the level of the neck and / or of the container body. Thus, the method according to the invention makes it possible to measure at least either an internal diameter of the neck or a thickness of the glass wall or an internal diameter of the neck and a thickness of the glass wall.

Likewise, the region to be inspected may correspond to a part of the wall 7 comprising the body, the rim or the bottom of the container. The regioninspect can also correspond to the whole of the container 2. The dimensions measured are thicknesses of the glass wall at the body, at the bottom, at the rim, heights, internal or external diameters, widths for example for threads on the neck. These measurements also make it possible to deduce a dimensional characteristic of the region to be inspected, such as, for example, the ovality of the container or a container with a tilted neck.

The method according to the invention is implemented for glass containers 2, that is to say for series of manufactured objects made up of a single material, namely glass. It is considered that the attenuation coefficient μ of the glass is unique, that is to say having the same value at any point of a region to be inspected of the containers and preferably constant over time and identical for the containers of series. These conditions are met because the composition of the glass is stable in furnaces producing several hundred tonnes of glass per day. It should be noted that the attenuation coefficient μ of the glass is strictly speaking a spectral property μ (λ) depending on the wavelength λ or the energy of the X-rays. This characteristic does not is not necessarily taken into account in the method according to the invention insofar as the X-ray source having its own emitted spectral composition, it is possible to consider that the attenuation μ is a characteristic of the glass for the spectrum of the source chosen. Those skilled in the art will also know how to carry out the invention using any method of taking into account the spectral attenuation of the beams. It will also be able to adapt the spectrum emitted, for example by hardening it spectral attenuation of the beams. It will also be able to adapt the spectrum emitted, for example by hardening it spectral attenuation of the beams. It will also be able to adapt the spectrum emitted, for example by hardening it

Consequently, the attenuation of air can be considered negligible compared to that of glass. The attenuation of an X-ray beam passing through the container will depend only, on the one hand, on said constant attenuation for the spectrum of X-rays emitted, and on the other hand, on the cumulative thickness of glass passed through. Alternatively, it is considered that the thickness of the air passed through is large and uniform for all the beams, so it can be considered to be known. The attenuation due to air can be subtracted from the total measured attenuation. Thus the gray level in each radiographic image, possibly corrected, depends solely and directly on the thickness of thetotal cumulative crossing glass. It is then possible to determine with precision the boundary surfaces which are the transitions between the air and the glass.

Thus, the computer system takes into account the attenuation coefficient of the glass of the containers being inspected for this calculation operation. Advantageously, the installation 1 comprises a device for making available for the computer system, the attenuation coefficient of the glass of the containers, for example known from the analyzes of the glass in the oven. This provisioning device can be produced by a mass memory, a man-machine interface or by a wired or wireless computer network.

The installation 1 also comprises a device 11 for transporting the containers 2 in a conveying plane Pc, along a plane path, with a direction materialized by a displacement vector T. Preferably, the path is substantially rectilinear. Conventionally, the transport device 11 is a conveyor belt or chain conveyor ensuring linear translation of the containers in the upright position, that is to say with the bottom 3 of the containers resting on the conveyor to settle in the plane. of conveying Pc.

The installation according to the invention allows the implementation of a method for automatically carrying out measurements of linear dimensions on containers 2 moving in scrolling at high speed. The invention relates to so-called “on-line” control of a series of containers, after a processing or manufacturing step, in order to control the quality of the containers or of the processing or manufacturing process.

The method operates for a scrolling rate of a flow of containers 2. Ideally, the plant 1 is capable of processing production at the production rate, for example of 600 containers per minute.

However, the calculation time may exceed the interval between two vessels. Likewise, the exposure times of the image and reading sensors may be too long. If the fastest flow cannot be processed by a single installation according to the invention, then several installations can be implemented in parallel, each controlling

part of the production. Thus it is possible to divide the production flow into two or three parallel flows inspected by two or three installations according to the invention. Obviously, the economic interest of the invention is achieved if the number of flows and therefore of installations according to the invention remains low.

The invention brings a considerable improvement thanks to the measurement of the internal surface and the thickness of the walls, without contact and by scrolling of the containers, the complex operations of rotating the articles as implemented in carousels are eliminated. . This also allows for thickness mapping over the entire periphery and over the entire height of the inspected region. For checking the neck, the invention allows measurements in the neck, for all production containers, while the prior art only performs a binary conformity test per template or measurements on a few samples taken. These measurements therefore allow an observation of the drifts of the manufacturing process.

As emerges more precisely from Figs. 1 and 2, the direction of movement of the receptacles 2 is established along a horizontal axis X with an X, Y, Z coordinate system comprising a vertical axis Z perpendicular to the horizontal axis X and a transverse axis Y perpendicular to the axis vertical Z and to the horizontal axis X, and X and Y being in a plane parallel to the conveying plane Pc which is substantially horizontal.

As emerges more precisely from FIG. 4, during their translational movement, the containers 2 generate or pass through a so-called conveying volume Vt. The plane Ps is the secant plane of the conveying volume Vt, orthogonal to the conveying plane Pc and parallel to the direction of movement T. For example, a median plane separates the volume into two equal sub-volumes. The plane Ps is a vertical plane insofar as the conveying plane is generally horizontal.

The installation 1 also comprises, as illustrated in FIGS. 1 and 2, at least one focus Fj (with j varying from 1 to k) of an X-ray generator tube 12 creating a divergent beam of X-rays directed to pass through the conveying volume Vt and more precisely to cross at least Its region atinspect container 2. It should be noted that container 2 is made of glass so that the region to be inspected of the container is made of a material whose transmission absorption coefficient is homogeneous for a given X-ray radiation.

Installation 1 also includes at least three image sensors Cji (with i varying from 1 to N, N greater than or equal to 3) sensitive to X-rays and located so as to be exposed to X-rays coming from a focus Fj associated and having passed through the conveying volume Vt and more precisely, at least the region to be inspected of the container 2. Of course, the tube 12 and the image sensors Cji are located outside the conveying volume Vt to allow free movement containers in this volume. Conventionally, the X-ray generator tubes 12 and the Cji image sensors are placed in an X-ray sealed enclosure.

The X-ray beams coming from a focus Fj associated with said image sensor Cji, pass through at least the inspected region, and form on the image sensor, the radiographic projection of the inspected region, according to a projection direction Dji ( Fig. 1 and 2). The direction of projection Dji is the oriented direction of the vector starting from the focus Fj to pass through the center Mji of the image sensor Cji. The focal point (s) Fj and the image sensors Cji are arranged so that each image sensor receives a radiographic projection of the region to be inspected in a direction of projection of the region to be inspected.

The installation 1 also comprises an acquisition system linked to the image sensors Cji, so as to acquire for each container 2 during its movement, at least three radiographic projections of the region to be inspected having different directions. It is recalled that the direction of projection associated with the radiographic image obtained is the direction starting from the focal point and passing through the middle of the zone of the sensitive surface of the image sensor, at the time of acquisition of the image. Thus, the at least three radiographic projections have directions of projections which form two by two, an angle between them.

The acquisition system is connected to a computer system, not shown, but of all types known per se. According to an advantageous embodiment characteristic, the computer system records with the aid of image sensors Cji, for each container during its movement, radiographic images originating from a determined number of radiographic projections of the region to be inspected according to different projection directions. Typically, the number of different projection directions Dji is between three and forty, and preferably between four and fifteen. According to an advantageous variant embodiment, the installation 1 comprises between three and forty image sensors Cj. According to a preferred variant embodiment, the installation 1 comprises between four and fifteen image sensors Cji.

As will be explained in detail in the remainder of the description, the computer system is programmed to analyze, for each container, the at least three radiographic images originating from the at least three radiographic projections from different directions so as to determine, for each container, a digital geometric model of the region to be inspected containing the three-dimensional coordinates of a set of points belonging to the wall of the container in the inspected region. More precisely, each digital geometric model contains the three-dimensional coordinates of a set of points belonging at least to the internal surface of the wall of the container and preferably,

The determination of the three-dimensional coordinates of these points and the realization of the dimensional measurements can be carried out from any

appropriately by known techniques for analyzing three-dimensional geometric data.

In general, the digital geometric model of the region to be inspected contains the three-dimensional coordinates of a set of points, calculated from the at least three radiographic images of the region to be inspected. This set of points belongs to the internal and / or external surface of the wall of the container, with at least two three-dimensional points in space located in a plane not orthogonal to a direction of projection Dji.

Advantageously, the digital geometric model of the region to be inspected containing the three-dimensional coordinates of a set of points is formed by:

at least two three-dimensional points of space each belonging to an internal and / or external surface of the wall of the container and situated in a plane not orthogonal to a direction of projection Dji and not parallel to the direction T of displacement;

- and / or at least one surface representation of the internal and external surfaces of the wall of the container containing points not belonging to a plane orthogonal to a direction of projection Dji, and not belonging to a plane parallel to the direction T of displacement ;

- and / or at least one section of the region to be inspected, according to a plane different from a plane orthogonal to a direction of projection Dji and different from a plane parallel to the direction T of displacement

The dimensional measurements are then carried out according to one of the methods described in the remainder of the description.

In general, the dimensional measurements carried out on the digital geometric model of each container relate to at least one internal diameter of the neck measured on said model in a plane not orthogonal to a direction of projection Djï, and / or at least a thickness of the wall of the body measured on said model in a plane not orthogonal to a direction of projection Dji.

A preferred exemplary embodiment consists in determining, for each container, a digital geometric model representing the internal surface and the external surface of the container in the region to be inspected.

According to this example, the digital analysis of the radiographic images relating to each container makes it possible to construct for each of these containers a three-dimensional digital geometric model. In other words, for each container inspected by radiography, a three-dimensional digital geometric model is constructed from the radiographic images corresponding to said container. Optionally, this digital geometric model can simply be a stack of two-dimensional digital geometric models. The realization of a digital geometric model is the way - in mathematical, graphical and data structure terms - in which three-dimensional vessels are represented and manipulated in digital form in a memory of a computer system.

The modelization can be voluminal. The mono-material container can therefore be represented by voxels whose value represents a quantity of material. The voxel can be full, partially full or empty of material (in this case it is air). The geometric volume model can be analyzed to locate the boundaries of the container and then to measure linear dimensions such as lengths or thicknesses. It can also be transformed into a surface model, that is to say in which the boundary surfaces of the container are modeled.

I! It is possible to obtain a surface model directly from the radiographic images, that is to say without going through the calculation of a volume model.

In surface models, a container is defined by at least one three-dimensional surface. A three-dimensional surface corresponds to its boundary between the material of the container and the external environment (generally the air), which makes it possible to understand the concepts of inside and outside of the container. Generally three-dimensional surfaces are modeled in several ways such as by polygonal modeling, bycurves or parametric surfaces (cylinders, cones, spheres, splines, ...) or by subdivision of surfaces. Using a meshing of polyhedra, for example triangles, the three-dimensional surfaces of the containers are represented by sets of plane facets connected by their edges.

A section of a three-dimensional container is its intersection with a plane. Section three-dimensional surfaces are two-dimensional curves in the section plane. The knowledge of these two-dimensional curves in a succession of section planes allows the reconstruction of three-dimensional surfaces,

In order to carry out length measurements, there are several approaches.

In a first volume method, it is possible to travel through a volume model along a straight line or a bundle of straight lines and determine the material / air boundary voxels.

In a second surface method, it is possible to calculate a segment whose ends are the intersections of a line with the material / air boundary surface of a surface model. The algorithms solve topological problems quite well. The points of intersection are unique. Finally, a mixed method consists in transforming the solid model into a surface model, then in applying the second method.

A third method consists in determining in a cross section, the distance between two points of one or two two-dimensional curves, any curve being a border between matter and air.

A three-dimensional point is a point whose coordinates are known in three-dimensional space, in any frame of reference. These three previous methods are examples of determining a distance between two three-dimensional points, to determine a measure of linear dimension.

The objective of the invention is to carry out more complete measurements than those made possible by simple two-dimensional radiographic images. Indeed, it is easy using a matrix image sensor to obtain a two-dimensional radiographic image corresponding to a projection of the inspected region and to measure

dimensions in a plane orthogonal to the direction of projection called the “projected plane”. Likewise, it is easy, using a linear image sensor, to obtain a two-dimensional radiographic image corresponding to a fan projection (parallel pians) of the inspected region obtained by juxtaposition of the lines of successive images acquired during moving in the direction of travel T, and measuring dimensions in a projected plan, which is parallel to the direction of travel. On the other hand, according to the invention, it is possible to measure linear dimensions in directions which are neither contained in the projected planes, nor parallel to the projected planes. The method according to the invention consists in fact during the treatment of a combination of the radiographic images according to at least three different projection directions, to be reconstructed and dimensions measured according to practically all the directions. This is possible by any method allowing the determination of three-dimensional points in space belonging to a boundary surface included in the region to be inspected of the container. The reconstruction of a three-dimensional model of the region to be inspected, of surface or volume type or based on section planes, is one possible method. In fact, according to the invention, it is possible either indirectly from a surface or volume model or from planes of sections, or directly, to determine at least two three-dimensional points, or even preferably three-dimensional point clouds,

The digital geometric model is therefore made up of geometric elements such as points, segments, surfaces, elementary volumes, calculated from radiographic projections, considering to calculate each element, the attenuation of at least some X-rays that have passed through this point on the real empty container, with the aim that the digital geometric model is a faithful representation of the geometry of the real empty container, including deformations with respect to an ideal empty container. In other words, the coordinates of the geometric elements are determined by considering that said coordinates have modified the

radiographic projections, even when these geometric elements are indistinguishable in any of the 2D radiographic projections. The measurements of dimensions on the digital geometric model therefore give information on the dimensions of each modeled empty container, from geometric elements distinguishable in any of the radiographic projections.

Since the glass container is composed of a single material, therefore with a constant attenuation coefficient or considered as such, it is advantageous to determine its digital geometric model in the form of surfaces. It is possible to determine and represent in the digital geometric model, for example, the internal surface of the neck of the container. According to this example, the inspected region contains the neck 3 and therefore extends between the surface plane of the ring 6 and a plane which is parallel thereto. We can then measure the internal diameter of the neck D. More exactly, we can measure several internal diameters of the neck D. By choosing a given height for example by choosing a cutting plane parallel to the surface of the ring or to the bottom of the container, several diameters can be measured from 0 to 360 ° in this plane. So, it is possible to determine the diameter at the opening Do (or mouthpiece), for example 3 mm below the mouthpiece by positioning a cutting plane 3 mm below the ring surface. It is also possible to determine a minimum diameter D over the entire height h of the internal surface of the neck to replace the measurement by pinning.

Given the geometry of the containers, it is easier to reason in cylindrical coordinates. When carrying out the measurements on a container, the method has produced a digital geometric model MGN precisely representing at least the region to be inspected of said container corresponding to the neck, for example as illustrated in FIG. 14 or as illustrated in FIG. 15, a vertical section or four horizontal sections of the digital geometric model MGN of the container

We can define a coordinate system ZM, ρ, θ on this digital geometric model, with the axis ZM which corresponds to the axis of

symmetry of said container model, with the height Z along the ZM axis which is equal to zero when it is located in the laying plane. In the case of a cylindrical or conical container, ZM can be defined as an axis orthogonal to the laying plane and passing through the center of the bottom of the container. In fact, the digital geometric model MGN of a container comprises internal surfaces SI and external surfaces SE.

According to an advantageous variant for measuring the neck of each container, the method consists in measuring on the digital geometric model MGN, as internal diameters D of the neck, the lengths of a set of straight segments, said segments being:

• orthogonal to the axis of symmetry ZM of the digital geometric model,

• crossing the axis of symmetry ZM of the digital geometric model,

• located at at least two distinct heights ZG1, ZG2 in the neck of the digital geometric model;

• of directions distributed angularly around the axis of symmetry ZM of the digital geometric model, with at least one segment not orthogonal to the directions of projection Dij;

• for each height, in number greater than the number of directions of projections Dij;

- And each segment connecting two points which belong to the internal surface of the neck of the digital geometric model and which are opposite with respect to the axis of symmetry ZM of the digital geometric model of the container.

It should be noted that the segments would cross the axis of symmetry ZM exactly in the mathematical sense only in the case of ideal vessels of perfect revolution. This is obviously not the case since the digital geometric model represents a real container.

It is recalled that a main objective of the invention is to achieve online, that is to say when the containers are in rapid translation on a conveyor, and without the contact of a mechanical or pneumatic sensor,

several measures that are necessary, depending on the types of production, to ensure bottleneck compliance.

Broaching is the possibility of introducing a cylinder of minimum diameter, for example the filling cannula, into the neck. To measure the broaching according to the invention, the minimum diameter can be determined over several heights along the axis of symmetry ZM and in several directions at angles θ varying from 0 to 360 °. We can also simulate the introduction of a cylinder, inside the internal surface of the digital geometric model of each container, at the level of its neck, and determine the maximum diameter that the cylinder reaches when it is inscribed, therefore in contact without being able to magnify further, inside the internal surface of the neck or a set of points of said internal surface. To measure the unblocking profile of each container, the one can from the ring surface Zb of the digital geometric model, then step by step over a depth Zb-p determined from the ring surface, calculate at each height ZZ ∈ [Zb - p; Zb] a statistical data of the diameters such as for example the minimum diameter D at each depth or height Z, i.e. minθ D, deduce a profile function such as the minimum diameter as a function of depth, ie profile (Z) = min θ Ø (Z), and compare this profile with reference profiles.

To measure the diameter Do at the opening, for example at a depth of 3 mm, it can be checked that all the diameters D between the ring surface Zb up to the depth of 3 mm are contained within the tolerance interval.

According to an advantageous characteristic of this variant, the method consists, for measuring the thicknesses e of the wall of each container, in measuring a set of lengths of segments bringing together two by two points of the outer surface SE and points of the inner surface SI of the digital geometric model of each container. The segments measured are:

• preferably substantially orthogonal to one of the internal and external surfaces, preferably to the external surface SE;

• located at least two distinct heights ZE1, ZE2 in the region to be inspected;

• from directions close to rays starting from the axis of symmetry ZM and distributed angularly around the axis of symmetry of the digital geometric model, with at least one segment not orthogonal to the directions of projection Dij;

• for each height, in number greater than the double of the number of directions of projections Dij,

It is also possible to choose as the region to be inspected, for example the body 4 of the container extending between the rim and the shoulder. Thus the region to be inspected can be delimited by two planes parallel to the bottom 3 or to the plane of the receptacle, one positioned above the rim the other under the shoulder. The digital geometric model of the internal and external surfaces of the inspected region is then determined, which makes it possible to measure the glass thickness e between these surfaces at multiple points, thus providing a measure of the distribution of the glass.

As shown in Fig. 15, it is possible at least for two distinct heights ZE1, ZE2, to measure the thickness e of the wall along several radial segments orthogonal to the axis ZM and distributed from 0 to 360 °. This achieves at least the same function that optical sensors allow in a machine rotating the container, namely, to seek the minimum thickness on the circumference at one, two, three or four distinct heights.

According to the invention, the digital geometric model of the inspected region of each container comprises the internal SI and external SE surfaces. We can therefore determine the thickness e by measuring a large number of segments joining the external surface SE and the internal surface SI, distributed uniformly over the entire height Z and the directions θ, with a height step dZ and an angular step as fine as allowed by the resolution of the sensors and the digital geometric model calculated for each container. Thus, one can map the thickness in all or part of the inspection region, or even an entire container.

According to an alternative embodiment, the method is characterized in that a minimum thickness is calculated over the region to be inspected, or else a related zone of the wall having a thickness less than a tolerance threshold called "zone" is determined. thin ”and the quality of the container is decided as a function of the minimum thickness or the area and / or the shape of the area of ​​the thin zone.

According to an alternative embodiment, the region to be inspected corresponds to at least part of the neck 5 of the container so that the radiographic images are analyzed to construct a digital geometric model of at least the internal surface of the neck so that the internal diameter of the neck D can be measured and correspond to the measurement of a dimensional characteristic of the region to be inspected.

According to another variant embodiment, the region to be inspected corresponds to at least a part of the body 4 of the container so that the radiographic images are analyzed so as to construct a digital geometric model of the internal surface and of the external surface of the container in the portion of the wall inspected, and from the internal and external surfaces of the digital geometric model, to obtain the measurement of the thickness e of the glass wall of the body of the container lying between these surfaces.

According to a preferred variant embodiment, the region to be inspected comprises at least a part of the neck and a part of the wall of the body of the container so that the radiographic images are analyzed so as to construct a digital geometric model of the internal surface and of the outer surface of the container, and from the inner and outer surfaces of the digital geometric model, to obtain measurements of an inner diameter of the neck and the thickness of the glass wall of the body of the container.

It emerges from the preceding description that the invention makes it possible to construct for each container a digital geometric model corresponding at least to the region to be inspected comprising at least part of the neck and / or part of the body of each container. As

previously indicated, the digital geometric model is constructed using the attenuation coefficient of the glass constituting the receptacles 2.

Some of the preceding measurement methods amount to analyzing the geometry of the digital geometric model of each container according to successive sections at different heights Z, from planes orthogonal to the axis of symmetry ZM of the digital geometric model of the container, therefore horizontal sections, which are then analyzed in radial directions, by varying the measurement direction with the angle θ between 0 and 360 °. The same results are of course obtained by sections along planes secant to the axis of symmetry ZM of the containers, therefore vertical sections, distributed at angles θ between 0 and 360 °.

According to an advantageous variant embodiment, the digital geometric model is also constructed using an a priori geometric model of the inspected region making it possible to accelerate and make reliable the reconstruction calculations of the digital geometric model of each container.

Thus, the a priori geometric model is a geometric digital model of the series of containers, serving as an initialization for reconstruction software in order to build the digital geometric model of each inspected container. Its role is mainly to provide the computer system with information on the shape, geometry and dimensions of the object to be modeled by calculation.

Thanks to this a priori information, it becomes possible:

- not to model, from the radiographic images, the attenuation in regions of the image space empty of material a priori because the attenuation is considered there as zero;

and or

- to model from the radiographic images, only the surfaces on which the measurements of dimensions are to be made, possibly directly without going through the determination of voxels; and or

- to determine only the differences between the modeled surfaces from the radiographic images and the theoretical ideal surfaces.

The knowledge of the a priori geometric model of the glass containers also makes it possible not to determine from the radiographic images, attenuation values ​​in regions of space containing material according to the a priori model because it is known as that of the glass used.

However, it should be understood that according to the invention, no measurement of a container is deduced from a measurement on the a priori geometric model, since this model is known independently of said container and represents a non-real theoretical ideal.

Thus the a priori geometric model is a digital model of the series of receptacles, serving as an initialization for the reconstruction software.

The computer system therefore has an a priori geometric model of the region to be inspected in order to perform this calculation operation. Thus, the installation 1 comprises a device for making available to the computer system, an a priori geometric model of the region to be inspected for the containers or series of containers.

The device for making available to the computer system an a priori geometric model of the region to be inspected is a mass memory, a wired or wireless computer network or a man-machine interface.

According to a first variant of the invention, the a priori geometric model is obtained by the digital computer design model of the containers, produced during their design (3D CAD). In this case, it is made available to the computer system by various possible means, such as a connection through a computer network, to a database containing several CAD models corresponding to the various models of receptacles capable of being measured in production. , selection by the operator from a database internal to the installation, etc.

According to a second variant of the invention, the a priori geometric model is obtained from a geometric digital model constructed from the measurement of one or more containers of the same series (therefore of the same commercial model) by a measuring device. measurement, for example by a

probe measuring machine or axial tomography apparatus. The a priori geometric model can be constructed by merging the measurements of several vessels manufactured in the same series,

According to a third variant of the invention, the a priori geometric model is a geometric digital model generated by the computer system from values ​​entered and / or drawings made and / or shapes selected by an operator on the human interface. system machine.

For example, to provide the geometric model a priori in the case of checking the internal dimensions of the neck, the inspected region contains at least the neck, therefore the region of the container between the top of the ring and the shoulder of the container . The a priori geometric model of the neck can be a simple hollow truncated cone of which the height, the two top and bottom diameters, and the wall thickness are known. It can also be a complete geometric model, for example of a wine-type ring, with its external reliefs, against the ring, and rounded edges included. According to another example, the computer system can, via its interfaces, receive technical descriptions of the a priori model, comprising for example a type of standardized screw ring described either by a recorded 3D model, or by length parameters,

Likewise to provide the geometric model a priori in the case of a control of the distribution of glass at the level of the body of the container, the inspected region extends at least over an inspection height situated between the rim (or heel) and the shoulder. The a priori geometric model of the body can be a simple portion of a perfect hollow cylinder, of which only the external diameter, the height and the average thickness are indicated. The means of making the a priori digital model available can therefore be limited to the digital input or transmission of the values ​​of external diameter, height and thickness. Of course, these methods are easily generalized for containers of any shape, for example of polygonal section.

It should be understood that the a priori geometric model must at least contain sufficient technical, geometric,

topological and / or digital, to inform the computer system on the general three-dimensional structure of the series of receptacles, the degree of detail and precision of this information possibly being very low without penalizing the precision sought for linear measurements.

It is possible to configure the control by making virtual gauge positions available to the computer system. In this case, the device according to the invention obviously includes means for making the measurement tolerance intervals available.

Another way to determine dimension measurements and their conformity is by comparing the digital geometric model of the inspected region with a reference or theoretical geometric model.

The geometric reference model is an ideal model from the series of vessels inspected. To carry out a dimensional check, we can compare the digital geometric model of the inspected region of each container with the geometric reference model common to the series of containers, by an algorithm comprising the matching of the models, then the measurement of the differences between the models. The geometric reference model can be obtained from CAD at least for the external surface of the containers.

It is thus possible to carry out an operation of matching the digital geometric model of the inspected region of each container with the reference geometric model, then to determine dimensional differences by measuring distances between surface elements belonging to the model. reference and surface elements belonging to the digital geometric model. For example, one can measure according to the invention what the glassmakers call the "diameter at the opening", which is specified by a minimum and maximum diameter tolerance, for example a tolerance interval of 18 mm +/- 0.5, to a given depth from the ring surface, for example 3 mm. According to the invention, it is possible to virtually position a first cylindrical surface of height 3 mm,second cylindrical surface of height 3 mm, of minimum diameter containing the internal surface of each modeled container, and to consider as measurements of the diameter at the opening of each container the diameters of the inscribed and exinscribed cylindrical surfaces, which are respectively compared to the tolerances.

According to a variant of the invention, the geometric reference model and the a priori geometric model are the same geometric model.

According to another variant of the invention, the a priori geometric model is less precise, less complete and / or differs from the reference geometric model.

It emerges from the above description that the computer system determines for each container, at least one internal diameter of the neck and / or a thickness of the glass wall of the body of the container. In general, the invention makes it possible to carry out a series of measurements of dimensions on the containers 2. The dimensional control consists in measuring real dimensions and comparing them with the required dimensions. A priori, any container in a series is close to the ideal reference container having the required dimensions but deviates therefrom through dimensional variations. The objective is generally to compare the measurements obtained on the containers with the required values, for example defined by a quality department. These dimension measurements or the deviations of these measurements from the required values ​​can be displayed, saved, etc. They can also be used to make decisions on the conformity of the containers which can be sorted automatically. According to an advantageous characteristic of embodiment, the computer system is connected to a device for displaying the values ​​of linear measurements of the region to be inspected and / or the deviations. dimensional in relation to reference values. For example, the installation according to the invention may include a display screen for the radiographic images of the inspected region and of the measured dimensions. They can also be used to make decisions on the conformity of the containers which can be sorted automatically. According to an advantageous characteristic of embodiment, the computer system is connected to a device for displaying the linear measurement values ​​of the region to be inspected and / or the deviations. dimensional in relation to reference values. For example, the installation according to the invention may include a display screen for the radiographic images of the inspected region and of the measured dimensions. They can also be used to make decisions on the conformity of the containers which can be sorted automatically. According to an advantageous characteristic of embodiment, the computer system is connected to a device for displaying the linear measurement values ​​of the region to be inspected and / or the deviations. dimensional in relation to reference values. For example, the installation according to the invention may include a display screen for the radiographic images of the inspected region and of the measured dimensions.

According to an advantageous embodiment characteristic, the computer system is connected to a device for sorting the containers according to the linear measurement of the area to be inspected. Thus, this sorting device can eject from the transport device the containers considered to be defective in consideration of the measured linear dimensions.

Of course, the relative positions of the foci Fj and the image sensors Cji are diverse, it being remembered that the foci Fj and the image sensors Cji are positioned outside the conveying volume Vt.

According to an alternative embodiment, the installation 1 comprises a single hearth Fj = F1 arranged along one side of the conveying volume Vt and a series of image sensors Cji = C1i = C11, C12, C13, ... arranged according to the opposite side of the conveying volume Vt to receive the rays coming from the focus Fi and having passed through the region to be inspected. In this example, the focus has an opening Of which is measured in at least one unspecified plane, such as for example the X, Y plane in Fig. 1, which is greater than or equal to 120 °. This opening Of is considered at the outlet of the focal point, in the case where the installation comprises between the focal point and the volume Vt, or between the volume Vt and the image sensors, screens limiting the beams to only useful beams, in the goal of reducing the broadcast.

According to another variant embodiment, at least two focal points Fj (F1 and F2) for producing X-rays are positioned separately in two distinct positions and at least three image sensors Cji, sensitive to X-rays are placed so that each focal point is associated with at least one Cji image sensor, and each Cji image sensor is associated with a focal point and receives the X-rays coming from said focal point and passing through the region to be inspected. In this example, each hearth has an opening greater than or equal to 60 ° so that the sum of the openings of the two hearths is greater than or equal to 120 °.

In the exemplary embodiment illustrated in FIGS. 5 to 7, the installation 1 comprises three foci F1, F2, F3 each associated with a separate generator tube 12. Installation 1 also includes five image sensors C11, C12, C13, C14 and C15 each sensitive to X-rays from the first associated focus F1, five image sensors C21, C22, C23, C24 and C25 each sensitive to rays X from the second associated focus F2 and three sensors

of images C31, C32, C33 each sensitive to X-rays from the associated third focal point F3.

According to this exemplary embodiment, the installation comprises at least one focal point (and in the example, two focal points F1 and F2) from each of which a divergent X-ray beam emanates. At least one focus (and in the example, two foci F1 and F2) are positioned on one side of the secant plane Ps so that each of the beams crosses the secant yaws Ps and the region to be inspected, while at least one image sensor Cji associated with said focus Fj to receive the X-rays from said focus Fj is arranged on the opposite side with respect to the intersecting plane Ps. (In the example, these are the five image sensors C11, C12, C13, C14 and C15 each sensitive to X-rays coming from the associated focus F1 and the five image sensors C21, C22, C23, C24 and C25 each sensitive to X-rays coming from the associated focus F2). Of course,

According to an advantageous variant embodiment which is illustrated in FIGS. 5 to 7, a focal point Fj from which a divergent X-ray beam emanates is arranged on one side of the conveying plane Pc so that its beam crosses the conveying plane Pc, while at least one image sensor Cji is associated with said focus Fj to receive the X-rays from said focus is positioned on the opposite side with respect to the conveying plane Pc. In the example illustrated, a focal point F3 is placed above the conveying plane Pc while three image sensors C31, C32, C33 are positioned below the conveying plane Pc. Of course, the position between the focus and the image sensors can be reversed relative to the conveying plane.

According to an advantageous variant embodiment, at least one of the foci Fj is placed in the conveying plane Pc. Preferably, these foci cooperate with associated image sensors located at their opposite relative to the intersecting plane Ps, and thus in the case of transport of

containers arranged on a flat conveyor, this arrangement allows that in the X-ray images, the projections of the containers are not superimposed on the projection of the conveyor. Thus, in the digital geometric model of the containers, the part of the container in contact with the conveyor can be precisely determined.

According to an advantageous characteristic of embodiment, the arrangement of the image sensors Cji and of the focal points is such that the X-rays coming from the focal point (s) Fj and reaching the image sensors Cji only pass through one region to be inspected at a time. In other words, x-rays only pass through one container at a time. It should be noted that the installation may include a system for controlling the spacing between the successive moving containers, such as for example screws or belts in lateral contact with the containers.

An object of the invention is to obtain a method which is not only rapid, but also inexpensive, capable of calculating with the precision necessary for a dimensional check. The invention aims to reduce the number of images necessary for reconstruction to the minimum number making it possible to achieve the desired dimensional precision. For example, the invention makes it possible, with nine projections and a limited number of images of the inspected region, to measure the internal diameter of a cylinder at +/- 0.05 mm. Advantageously, the installation according to the invention comprises between one and four focal points Fj and preferably one or two focal points Fj and preferably between four and fifteen image sensors Cji.

According to the invention, it is advisable to arrange the image sensors and the focal point (s) so that the combination of the at least three directions of projections optimizes the determination of the digital geometric model of the inspected region, considering that it is necessary to leave the volume crossed Vt free for the circulation of the containers. The rules below are advantageously implemented within the framework of the invention, these rules being valid for linear or matrix image sensors.

In the following, an angle is an absolute value. Figs. 8 and 9 illustrate two directions of projection Dji and D'ji which are also

vectors. These Figures show the angle r between these two directions of projection, i.e. and s the angle complementary to the angle r,

let s = 180 ° -r. By definition, the useful angle a between two different directions of projection, Dji and D'ji, is the smallest of the angles r and s, or α = Min (r, s). Thus, the useful angle a is the smallest of the angles formed by the two straight lines bearing the directions of projection Dij, D'ji and brought back to any point of the inspected region.

According to an advantageous variant of the invention, at least two images from two radiographic projections in two different directions Dji and D'ji are acquired for each container, forming between them a useful angle a greater than or equal to 45 ° and less than or equal at 90 °. According to an advantageous variant embodiment, at least two images from two radiographic projections in two different directions forming between them a useful angle a greater than or equal to 60 ° and less than or equal to 90 ° are acquired for each container.

To do this, the installation 1 according to the invention comprises at least one focus and two image sensors arranged so that the directions of projection of the inspected region which they receive have between them a useful angle a greater than or equal to 45 ° and less than or equal to 90 ° and, advantageously greater than or equal to 60 ° and less than or equal to 90 °.

For example as illustrated in FIG. 5, the useful angle a between the directions D15 and D11, and between the directions D13 and D25 are greater than 45 °. Obviously it must be understood that at least one useful angle is greater than or equal to 45 ° and less than or equal to 90 ° and advantageously that at least one useful angle is greater than or equal to 60 ° and less than or equal to 90 ° and the other useful angles between two directions Dji are arbitrary. Those skilled in the art from this rule will know how to seek an arrangement which offers the most complete possible distribution of the directions of projections of the inspected region.

According to another advantageous characteristic, for each container, the computer system acquires at least one radiographic image of the

inspected region corresponding to a direction of projection forming an opening angle p determined with the direction of displacement T.

As illustrated in Figs. 10 and 11, the angle p between a direction of projection (vector Dji) and the trajectory of the receptacles (vector T) is considered, i.e. the angle p = (Dji, T) that is to say p = (D11, T) and p = (D12, T) in the example shown in Fig. 10 and p = (D22, T) and p = (D11, T) in the example illustrated in FIG. 11. The angle q complementary to the angle p is such that q = 180 ° -p. By definition, the opening angle β between a direction of projection Dji and the trajectory T is the smallest of the angles p and q, namely β = Min (p, q). Thus, the opening angle β is the smallest of the angles formed by the two straight lines one carrying the direction of projection Dji and the other the trajectory T, brought back to any point of the inspected region.

According to another advantageous characteristic, for each container, the computer system acquires at least one radiographic image of the inspected region corresponding to a projection direction Dji having with the direction of movement T, an opening angle β between 10 ° and 60 °. In other words, the installation according to the invention comprises at least one focus and one image sensor Cji arranged so that, when a container passes through the field of the image sensors, the projection direction Dji of the region inspected on the image sensor Cji makes an opening angle β with the direction of movement T of between 10 ° and 60 °.

In other words, the configuration of the installation 1 is optimized to reduce its size in the direction of movement while maintaining a traversed volume Vt suitable for the containers and a good quality of reconstruction.

Due to the volume Vt traversed, the installation does not produce a projection around the direction of displacement T. The volume traversed Vt imposes a minimum beta angle. According to the invention β min = 10 °. There is no sensor arranged so as to provide a projection of angle p less than 10 °.

It must be deduced from the above that the distribution of the angles of projections for each container is not uniform according to the invention.

Comme illustré à la Fig. 9, la répartition des angles de projection présente une lacune, qu'on appelle une région d'angle mort, de deux fois 2 × 10° soit 20°, au lieu d'avoir une couverture complète sur 180°.

For example as illustrated in Fig, 10, an installation according to the invention comprises at least one focus F1 and two image sensors C11, C12 whose directions of projections D11, D12 define with the direction of displacement T, an angle d 'opening β between 10 ° and 60 ° corresponding respectively to the angles p and q. In the example illustrated in FIG. 11, the installation comprises at least one image sensor C11 associated with a focal point Fi and an image sensor C22 associated with a focal point F2. The directions of projections D11, D22 define the opening angle β between 10 ° and 60 ° and corresponding to the angles p. Likewise, the installation illustrated in FIG. 5, comprises an image sensor C11 associated with the focus F1 and the direction of projection D11 of which forms an angle β between 10 ° and 60 °,

Cji image sensors are of the matrix or linear type.

According to a preferred variant embodiment, the installation 1 comprises linear image sensors. According to this preferred variant, each image sensor Cji comprises a linear array of elements sensitive to X-rays, distributed along a support line Lji defining with the associated focus Fj, a projection plane Pji containing the direction of projection Dji (Fig. . 2). These image sensors Cji are arranged so that at least m sensitive elements of each of these image sensors receive the radiographic projection of the region to be inspected by the X-ray beam coming from the associated focus Fj, with the planes of projection Pji for the various image sensors which are distinct from one another and not parallel to the conveying plane Pc. The number m of sensitive elements of each sensor of linear images is greater than 128, preferably greater than 512. The distance between neighboring sensitive elements (called “pitch” or “pitch”) and / or the dimension of the sensitive elements is preferably less than 800 μm. The reading frequency of the image lines is preferably greater than 100 Hz, advantageously greater than 1 kHz. Good

of course, these parameters are adapted according to the size of the receptacles, the required precision and the scroll speed.

According to an advantageous embodiment characteristic, at least three linear Cji image sensors have their support lines Lji parallel to each other.

According to another advantageous embodiment characteristic, at least three linear image sensors Cji have their support lines Lji orthogonal to the conveying plane Pc.

According to a variant, a focus Fj is positioned so that its beam passes through the inspected region and then the conveying plane Pc. In addition, at least one associated linear image sensor Cji is positioned opposite the focus Fj relative to the conveying plane Pc and so that its straight support Lji is parallel to the conveying plane Pc.

According to these variant embodiments with linear image sensors, the acquisition system acquires, using each of the at least three image sensors Cji, at each incremental displacement of each container on the trajectory, radiographic linear images of the region to be inspected according to a number chosen so that for each container, the whole of the region to be inspected is represented completely in the set of radiographic linear images. Thus, when moving a container, each image sensor is able to acquire linear radiographic images so that the whole of the region to be inspected of the container is completely represented in the set of linear radiographic images obtained at from said image sensor. So, for each container, at least three sets of radiographic linear images of the region to be inspected are obtained which are then analyzed. It is possible to constitute matrix radiographic images of the inspected region, by juxtaposing sets of radiographic linear images. But the reconstruction of the geometric model and the measurement do not necessarily impose it.

It should be noted that given the volume Vt traversed, no radiographic projection is acquired in the blind spot region

(β <± 10 °) located on either side of the direction of movement T. The method according to the invention makes it possible, despite the absence of radiographic projections in this interval of angles, to reconstruct, thanks to the geometric model a priori, a precise and complete digital geometric model of the container. It is thus possible to carry out linear dimension measurements over the entire digital geometric model and in particular in directions not orthogonal to the possible projection directions, including linear dimension measurements in measurement directions orthogonal to the corresponding missing projection directions. to the blind spot region located on either side of the direction of movement T. In fact, without the method according to the invention,

The incremental displacement is the translation performed by the container between two successive acquisitions of images. For a given speed of movement of the containers, the incremental displacement is internally limited by the speed of reading of the image sensors. This parameter, combined with the vertical resolution of the linear image sensors, (or with the horizontal and vertical resolutions of the matrix image sensors), conditions the density of measured points of the digital geometric model, and therefore ultimately Its spatial resolution and precision measuring the dimensional characteristic of the region to be inspected. For example, the incremental displacement may be less than 0.5 mm, preferably less than 0.2 mm, which means that the sensors of

Of course, the number of focal points, the number of image sensors associated with each focal point, and their relative arrangements are chosen from the outset. in an appropriate manner depending on the degree of measurement accuracy desired, the shape of the containers and their spacing on the conveyor.

The invention allows the measurement of dimensions (for dimensional control) on glass containers moving at high speed and without contact, by at least three X-ray projections from different directions, and by means of an optimal, rapid and sufficiently accurate calculation, thanks to to the mono-material property and by a priori knowledge of the general shape of the receptacles.

It should be noted that in glassworks, it is possible that several series of different containers are present at the same time on the same control line. The installation according to the invention can be used to inspect a flow of receptacles composed of several different series, for example a first series and a second series. In this case, the installation comprises a system for indicating to the computer system the series to which each of the receptacles belongs in order to implement the method of the invention for all the receptacles of the same series. In other words, the installation is provided with a means for making available to the computer system an a priori geometric model of each series of receptacles, and the computer system is adapted in order to

The invention is not limited to the examples described and shown because various modifications can be made to it without departing from its scope.
CLAIMS

1 - A method of measuring the dimensions of at least one region to be inspected of empty glass containers of a series (2) each having a wall forming a gouiot and a body and delimited by an internal surface and an external surface, the method consists in :

- choosing at least one region to be inspected comprising at least part of the neck and / or part of the body of the container;

- transporting the containers placed on their bottom in a conveying plane (Pc) along a plane path with a direction materialized by a displacement vector (T), these containers generating a conveying volume (Vt) during their displacement;

- position, on either side of the region to be inspected, at least one focus (Fj) of an X-ray generator tube and image sensors (Cji) sensitive to X-rays and each exposed to X-rays coming from an associated focal point (Fj), these X-rays having passed through at least the region to be inspected producing on each image sensor a radiographic projection in the direction of projection (Dji);

- acquire using image sensors (Cji) for each container during its movement, at least three radiographic images of the inspected region, obtained from at least three radiographic projections of the region to be inspected, the directions of which projection are different;

- constructing using a computer system, a digital geometric model of the region to be inspected for each container, from at least three radiographic images, said geometric model containing the three-dimensional coordinates of a set of points, calculated from at least three radiographic images, this set of points belonging to the internal and / or external surface of the container wall, with at least two points located in a plane not orthogonal to a direction of projection (Dji),

- deduce at least one internal diameter of the neck measured on the model in a plane not orthogonal to a direction of projection (Dji), and / or at least one thickness of the wall of the body measured on the model in a plane not orthogonal to a direction of projection (Dji).

2 - Method according to claim 1, characterized in that the digital geometric model of the region to be inspected containing the three-dimensional coordinates of a set of points consists of:

- at least two three-dimensional points of space each belonging to an internal and / or external surface of the wall of the container and located in a plane not orthogonal to a direction of projection (Dji), and not parallel to the direction (T) of displacement ;

- And / or at least one surface representation of the internal and external surfaces of the wall of the container containing points not belonging to a plane orthogonal to a direction of projection (Dji), and not belonging to a plane parallel to the direction (T) of movement;

- and / or at least one section of the region to be inspected, according to a plane different from a plane orthogonal to a direction of projection (Dji) and different from a plane parallel to the direction (T) of displacement

3 - Method according to one of the preceding claims, characterized in that it consists in choosing as the region to be inspected, at least one defined zone extending between two planes parallel to the conveying plane (Pc).

4 - Method according to one of the preceding claims, characterized in that it consists in measuring the neck of each container, in measuring as internal diameters of the neck, the lengths of a set of straight segments, said segments being:

• orthogonal to the axis of symmetry of the digital geometric model;

• crossing the axis of symmetry of the digital geometric model;

• located at least two distinct heights (ZG1, ZG2) in the neck of the digital geometric model;

• of directions distributed angularly around the axis of symmetry of the digital geometric model, with at least one segment not orthogonal to the directions of projection (Dij);

• for each height, in number greater than the number of directions of projections (Dij);

- And each segment connecting two points which belong to the internal surface of the neck of the digital geometric model and which are opposite with respect to the axis of symmetry of the digital geometric model of the container.

5 - Method according to claim 4, characterized in that the minimum diameter is calculated over several heights and several directions of the neck of the digital geometric model, so as to determine the measurement of pinning or diameter at the opening.

6 - Method according to one of the preceding claims, characterized in that it consists for measuring the thicknesses of the wall of each container, in measuring a set of lengths of segments bringing together two by two points of the outer surface and points on the interior surface of the digital geometric model of each container, the measured segments being:

• substantially orthogonal to one of the internal and external surfaces, preferably to the external surface;

• located at least 2 distinct heights (HE1, HE2) in the area to be inspected;

• directions close to rays starting from the axis of symmetry and distributed angularly around the axis of symmetry of the digital geometric model of the container, with at least one segment not orthogonal to the directions of projection (Dij);

• for each height, in number greater than double the number of projection directions (Dij).

7 - Method according to the preceding claim, characterized in that one calculates a minimum thickness on the region to be inspected, or one determines a related zone of the wall having a thickness less than a tolerance threshold called "thin zone And the quality of the container is decided as a function of the minimum thickness or the surface and / or the shape of the zone of the thin zone.

8 - Method according to one of the preceding claims, characterized in that one positions on one side of the path, a focus from which a diverging X-ray beam of aperture> 120 ° or at least two foci of which are issued. from diverging X-ray beams with a sum of the apertures greater than or equal to 120 °.

9 - Method according to one of the preceding claims, characterized in that it consists in having at least one focus in the conveying plane (Pc).

10 - Method according to one of the preceding claims, characterized in that it consists in:

- have a secant yaw (Ps) of the conveying volume on one side

(Vt), orthogonal to the conveying plane (Pc), a focus (Fj) from which a divergent X-ray beam emerges, so that its beam crosses the secant plane (Ps) and the region to be inspected;

- Having on the opposite side with respect to the secant plane (Ps), at least one image sensor (Cji) associated with said focus (Fj) to receive the X-rays coming from said focus (Fj).

11 - Method according to one of the preceding claims, characterized in that it consists in;

- Have on one side of the conveying plane (Pc), a focus (Fj) from which a divergent X-ray beam emerges, so that its beam passes through the conveying plane (Pc);

- Having on the opposite side with respect to the conveying plane (Pc), at least one image sensor (Cji) associated with said focal point (Fj) to receive the X-rays coming from said focal point (Fj).

12 - Method according to one of the preceding claims, characterized in that it consists in acquiring using image sensors (Cji), for each container during its movement, at least two radiographic images of the inspected region corresponding to projection directions (Dji) defining a useful angle (a) greater than or equal to 45 ° and less than or equal to 90 ° and, advantageously greater than or equal to 60 ° and less than or equal to 90 °.

13 - Method according to one of the preceding claims, characterized in that it consists in acquiring using image sensors (Cji), for each container during its movement, at least one radiographic image of the inspected region corresponding to a direction of projection (Dji) having an opening angle (β) with the direction of displacement (T) of between 10 ° and 60 °.

14 - Method according to one of the preceding claims, characterized in that it consists in acquiring using the image sensors (Cji), for each container of the series during its movement, no radiographic image of the inspected region corresponding to a direction of projection (Dji) having an opening angle (β) with the direction of displacement (T) of less than 10 °.

15 - Method according to one of the preceding claims, characterized in that it consists in making and acquiring radiographic projections of the inspected region of a container so that the X-rays coming from the focal point (s) and reaching the image sensors (Cji) do not pass through other containers.

16 - Method according to one of the preceding claims, characterized in that it consists in acquiring using image sensors (Cji), for each container during its movement, radiographic images from between three and forty radiographic projections of the region to be inspected from different directions.

17 -Procédé according to one of the preceding claims, characterized in that it consists in acquiring using image sensors (Cji), for each container during its movement, radiographic images from between four and fifteen radiographic projections of the area to be inspected from different directions.

18 - Method according to one of the preceding claims, characterized in that:

- the image sensors (Cji) are of linear type each comprising a linear array of elements sensitive to X-rays, distributed along a support line (Lji) defining with the associated focus (Fj), a plane of projection (Pji) containing the direction of projection (Dji), these image sensors being arranged so that:

• at least m sensitive elements of each of these image sensors receive the radiographic projection of the region to be inspected by the X-ray beam coming from the associated focus (Fj);

• the projection planes (Pji) for the different image sensors are distinct from one another and not parallel to the conveying plane (Pc);

- using each of the at least three linear image sensors (Cji) is acquired, at each incremental displacement of each container along its trajectory (T), linear radiographic images of the region to be inspected according to a number chosen in order to that for each container, the entire region to be inspected is represented completely in the set of radiographic linear images;

the at least three sets of radiographic linear images of the region to be inspected are analyzed for each container.

19 - Method according to one of the preceding claims, characterized in that it consists in making available to the computer system, an a priori geometric model of the region to be inspected of the series of containers, obtained by:

- the digital computer design model of the series containers;

- or the geometric digital model obtained from the measurement of one or more receptacles of the same series by a measuring device;

- or the geometric digital model generated by the computer system from values ​​entered and / or drawings produced and / or shapes selected by an operator on a man-machine interface of the computer system.

20 - Method according to one of the preceding claims, characterized in that it consists in making available to the computer system the value of the attenuation coefficient of the glass constituting the containers.

21 - Installation for automatic measurement of linear dimensions of at least one region to be inspected of empty glass containers (2) each having a wall forming a neck and a body and delimited by an internal surface and an external surface, the installation comprising :

- a device (11) for transporting the containers in a direction materialized by a displacement vector (T), along a substantially rectilinear path in a conveying plane (Pc), the containers traveling through a conveying volume (Vt) extended in the direction (T);

- at least one focus (Fj) of an X-ray generator tube (12) located outside the volume crossed (Vt), and creating a divergent beam of X-rays directed to pass through at least one region to be inspected comprising at least one part of the neck and / or part of the body of the container;

- at least three image sensors (Cji), located outside the conveying volume (Vt), so as to receive X-rays from an associated focus (Fj), the focus (s) (Fj) and the sensors images (Cji) being arranged so that each image sensor receives the radiographic projection of the region to be inspected by the rays coming from the focal point (Fj) when the container passes through these rays, the directions of projection of these radiographic projections being different from each other;

an acquisition system linked to the image sensors (Cji), so as to acquire for each container during its movement, at least three radiographic images of the region to be inspected, obtained from at least three radiographic projections of the region to be inspected, with different projection directions;

- and a computer system analyzing the at least three radiographic images, coming from at least the three different radiographic projections, so as to construct for each container, a digital geometric model of the region to be inspected, said digital geometric model containing the three-dimensional coordinates a set of points, calculated from the at least three radiographic images, this set of points belonging to the internal and / or external surface of the wall of the container, with at least two points located in a non

orthogonal to a direction of projection (Dji), each digital geometric model making it possible to deduce at least one internal diameter of the neck measured on the model in a plane not orthogonal to a direction of projection (Dji), and / or at least a thickness of the wall of the body measured on the model in a plane not orthogonal to a direction of projection (Dji).

22 - Installation according to claim 21, characterized in that it comprises at least two foci (F1, F2) for producing X-rays, positioned separately in two distinct positions and at least three image sensors (Cji), sensitive to X-rays and positioned so that:

- each focus emits its beam through at least the region to be inspected to reach at least one associated image sensor (Cji);

- each image sensor (Cji) is associated with a focus and receives the X-rays from said focus after having passed through the region to be inspected.

23 - Installation according to one of claims 21 to 22, characterized in that it comprises at least one focal point from which a divergent beam of X-rays emerges with an opening greater than or equal to 120 ° or at least two focal points of which are from diverging X-ray beams with a sum of the apertures greater than or equal to 120 °.

24 - Installation according to one of claims 21 to 23, characterized in that it comprises at least one hearth disposed in the conveying plane (Pc).

25 - Installation according to one of claims 21 to 24, characterized in that it comprises:

- on one side of a plane secant (Ps) to the conveying volume and orthogonal to the conveying plane (Pc), a focus (Fj) from which a divergent X-ray beam emerges, so that its beam crosses the plane secant (Ps) and the region to be inspected;

- on the opposite side with respect to the secant plane (Ps), at least one image sensor (Cji) associated with said focus (Fj) for receiving the X-rays coming from said focus (Fj).

26 - Installation according to one of claims 21 to 25, characterized in that it comprises:

- on one side of the conveying plane (Pc), a focus (Fj) from which a divergent X-ray beam emerges, so that its beam passes through the conveying plane (Pc);

- on the opposite side with respect to the conveying plane (Pc), at least one image sensor (Cji) associated with said focus (Fj) for receiving the X-rays coming from said focus (Fj).

27 - Installation according to one of claims 21 to 26, characterized in that at least one focus and two image sensors (Cji) are arranged so that the directions of projection (Dji) of the inspected region they receive between them a useful angle (a) greater than or equal to 45 ° and less than or equal to 90 ° and, advantageously greater than or equal to 60 ° and less than or equal to 90 °.

28 - Installation according to one of claims 21 to 27, characterized in that at least one focus (Fj) and an image sensor (Cji) are arranged so that, when a container (2) passes through the field image sensors, the direction of projection (Dji) of the region inspected on the image sensor (Cji) makes an opening angle (β) with the direction of displacement (T) of between 10 ° and 60 ° .

29 - Installation according to one of claims 21 to 28, characterized in that the image sensors (Cji) and the foci (Fj) are arranged so that the X-rays coming from the foci and reaching the sensors of images (Cji) and crossing the region of one container do not cross other containers at the same time.

30 - Installation according to one of claims 21 to 29, characterized in that it comprises between one and four foci (Fj), from one or more tubes generating X-rays.

31 - Installation according to one of claims 21 to 30, characterized in that the number and arrangement of image sensors (Cji) and associated foci, are such that for each container (2) during its movement, the X-ray projections of the area to be inspected on the Image sensors exhibit between three and forty different projection directions.

32 - Installation according to claims 21 to 30, characterized in that the number and arrangement of image sensors (Cji) and associated foci, are such that for each container (2) during its movement, the radiographic projections of the region to be inspected on the image sensors have between four and fifteen different projection directions.

33 - Installation according to one of claims 21 to 32, characterized in that:

- the image sensors (Cji) are of the linear type and each comprise a linear network of elements sensitive to X-rays, distributed along a support line (Lji) defining with the associated focus (Fj), a projection plane ( Pji) containing the direction of projection (Dji), these image sensors being arranged so that:

• at least m sensitive elements of each of these image sensors receive the radiographic projection of the region to be inspected by the X-ray beam coming from the associated focus (Fj);

• the projection planes (Pji) for the different image sensors are distinct from one another and not parallel to the conveying plane (Pc).

34 - Installation according to the preceding claim, characterized in that at least three image sensors (Cji) linear have their support lines (Lji) parallel to each other.

35 - Installation according to one of claims 33 and 34, characterized in that at least three image sensors (Cji) linear have their support lines (Lji) orthogonal to the conveying plane (Pc).

36 - Installation according to one of claims 33 to 35, characterized in that a focus (Fj) is positioned on one side of the conveying plane (Pc), and in that at least one image sensor (Cji) linear associated, is positioned on the side opposite the hearth (Fj) relative to the conveying plane (Pc) and so that its straight support (Lji) is parallel to the conveying plane (Pc). 37 - Installation according to one of claims 21 to 36, characterized in that it comprises a device for making available for the computer system, the attenuation coefficient of the glass constituting the containers.

38 - Installation according to one of claims 21 to 37, characterized in that it comprises a device for making available for the computer system, an a priori geometric model of the region to be inspected which is a mass memory, a wired or wireless computer network or a man-machine interface.

39 - Installation according to one of claims 21 to 38, characterized in that it comprises a device for making available for the computer system, values ​​and / or tolerances for the dimensions of the neck and / or minimum value d 'glass thickness for the body wall, and / or at least one reference geometric model of a container.