Description:4. DESCRIPTION
FIELD OF THE INVENTION
This invention relates to a digital image to screen exposing or imaging or engraving machine. This invention more particularly relates to a machine for exposing design available in a digital form on both a flat as well as a rotary screen. This invention also discloses a method for exposing of a digital image having “m by n” pixel size using a print head of “p by q” pixel size on both the flat screen and the rotary screen using the said machine.
The machine as per the present invention can be used for exposing both the flat screens and rotary screens for batch or mass printing using a single setup. Further, the said machine can be used for exposing the flat screens for textile sampling as well as the rotary screens used for mass printing in a single setup. The said machine eliminates machine specific variations in the print quality on the flat and rotary screens, reduces machine cost, maintenance cost, labor cost and space required.
BACKGROUND OF THE INVENTION
Printing on fabric with a combination of color and design is termed as a textile printing. Different techniques and machines are used for printing of a design created by designer on a fabric.
Screen printing technique is an extension of stencilling and is most common method of textile printing at industrial scale. In screen printing, an ink-blocking stencil is supported by a woven mesh. Ink or other printable materials is transfer through open areas of mesh formed by the stencil. This is pressed through the mesh as a sharp-edged image onto a substrate. A roller or squeegee is moved across the screen stencil, forcing or pumping ink past the threads of the woven mesh in the open areas. This type of printing has increased enormously in its use in recent years because of its versatility and the development of rotary screen printing machines which are capable of very high rates of production.
Two main types of screen printing technique include a flatbed screen printing and rotary screen printing. Flatbed screen printing can be manual or automatic. Rotary screen printing is usually automatic and gives the highest printing productivity. Screen printing involves passing the print paste onto a fabric through a mesh or screen which has some open and some blocked areas according to the desired print pattern. The print design obtained on the fabric depends on the pattern of the open areas of the screen.
Textile sampling is quite important and it is necessary to make a sample before printing the entire batch. First of all, a test print is done to visualize actual printing on the fabric which is also called a proof. Many printing units combine digital textile printing and rotary screen printing. Both print forms have their own advantages and disadvantages. Using two printing processes side by side create an issue related to textile sampling. Important question is, can you make a digital sample for a design that will be printed conventionally?
Samples have been made long before the invention of digital textile printing, but the conventional making of samples takes a lot of time as are preferably printed directly on a piece of fabric. This gives the best comparison with what the final printing result looks like. For rotary screen printing, screens have to be made in order to be able to print on textile. But as it is costly to make rotary screen, flat screen are used on a sampling table to make sample. As flat screens and rotary screens are made on different machines, results of rotary screen printing differ from the sample print results from the flat screen printing and hence there is a greater chance of non-acceptance of printed textile lots. For each change and corresponding test round, new flat screens have to be produced.
In contrast to conventional printing, digital textile printing directly prints a sample on textile. With digital textile sampling, a piece of textile is printed much quicker. As there is no limitations in the amount of samples produce digitally, it is easy to create a series of designs that are not yet in production.
Because of the advantages associated with digital printing, it seems a good idea to print digital samples, even if the final design is printed with rotary screen printing. However, it is to be noted that digital can print much better quality than rotary screen printing can match. Therefore, the resolution of digital samples is much higher than that of the conventional printers can reproduce using production run using rotary screens. This results into the rejection of the printed lot.
So, it is crucial to decide about the methodology to be used for textile sampling and final printing. Available options include (i). to prepare textile sampling with flat screens on a textile sampling table and then printing of the textile lot with rotary screen printing, (ii). printing of textile sample digitally and then print the textile lot with rotary screen printing and, (iii). digital printing of textile samples as well as digital printing of textile lot.
Option (ii) result into considerable variation in the final print resolution on the textile lot in comparison to the digitally printed textile samples, hence not advisable. Option (iii) is much more costly in terms of initial investment as well as per unit printing cost. Option (iii) can be advantageous for short print runs with variety of print designs because of its flexibility.
Additionally, each printing system (i.e. digital printing and rotary screen printing) has its own unique benefits and choice of method depends on the application. The longer the print run the cheaper the unit cost of each item printed by the rotary screen printing. This makes rotary screen printing a viable option for many visual applications like retail fashion and decor.
Photolithography is a process of making pattern using a photo resist and light which is mainly Ultraviolet (UV) light. Photoresist are of two types negative and positive. A negative photoresist is a type of photoresist in which the portion of the photoresist that is exposed to light becomes insoluble to the photoresist developer. The unexposed portion of the photoresist is dissolved by the photoresist developer. A positive photoresist is a type of photoresist in which the portion of the photoresist that is exposed to light becomes soluble to the photoresist developer. The unexposed portion of the photoresist remains insoluble to the photoresist developer. Photolithography has lot of applications. It is used in semiconductor wafer making, Printed Circuit Board (PCB) etching to printing. The end uses are many.
Traditionally the patterns are exposed using films on which patterns are made by hand or else printed from a printer or plotter. Then, several other technologies are introduced that can be mainly divided in two categories mask or mask less. In mask, a pattern is created using a mask material such as ink or wax. The ink or wax is jetted drop by drop using a device mainly inkjet print heads. In mask less the light of curing (which is mainly UV light) is projected in a way to make pattern. This mainly uses the light source from LASERs, LASER diodes, or Light-emitting Diode (LED). Known methods include use of an array of LASER diodes arranged in 1D or 2D array and then switching them on and off with the relative motion between them and the substrate. Other option is to use micro mechanical small mirror or other reflecting items arranged in 1D or 2D array. The light is projected over them and the mirrors are controlled to either direct the light to substrate or away from substrate. Controlling the mirrors along with the relative motion between the device and substrate can create a pattern. There are several patents for the above.
The substrates or mainly the screens are in two forms. They are either in a flat form known as a flat screen or round and cylindrical form known as a rotary screen. Till now there is no single device available which can expose patterns on flat as well rotary screens eliminating machine specific variations.
DESCRIPTION OF THE RELATED ART
Patent no. US7607745B2 discloses apparatus for digital printing in general and, in particular, to a high-speed digital garment printing machine. Patent no. US9013530B2 discloses a media processing device that processes media, to a printing device that prints on media and to a control method of the media processing device which is directed to suppressing a drop in processing efficiency.
Indian patent application no. 1975/DEL/95 discloses an automatic rotary screen textile printing machines, that prevent the fabric transporting endless screen from traveling zigzag to thereby improve the accuracy of width wise screen adjustment or obviate width wise pattern misregister, and also eliminate uneven printing and variations in colour density.
OBJECT OF THE INVENTION
Principal object of the present invention is to provide a screen exposing machine that can be used for exposing of designs on both rotary as well as flat screen for batch or mass printing.
Another object of the present invention is to provide a screen exposing machine that can be used for exposing designs on flat screens for textile sampling as well the rotary screens used for mass printing in a single setup.
Another object of the present invention is to provide a screen exposing machine that can be used to hold the rotary screens of different length and diameter for exposing designs on it.
Another object of the present invention is to provide a screen exposing machine that eliminates machine specific variations in the design exposed on the flat and rotary screens.
Another object of the present invention is to provide a screen exposing machine that is provided with linear and rotary encoders for synchronizing print head movement on the flat and the rotary screens for eliminating variations in the design exposed on the flat and rotary screen due to variation in the screen geometry.
Textile sampling is quite important and it is necessary to make a sample before printing the entire batch to visualize actual printing on the fabric. In case of mass printing requirement, rotary screen printing is most economical solution as it takes lesser time for printing. For rotary screen printing, series of rotary screens are required to be made in order to be able to print on textile. Cost of making rotary screen for rotary screen printing is higher. Hence, flat screen are used on a sampling table to make textile print sample. In practice, because of no availability of machines that can perform printing on both flat screen as well as rotary screens, flat screens used for sampling and rotary screens used for production are made on different machines. Results of rotary screen printing differ from the sample print results from the flat screen printing and hence there is a greater chance of non-acceptance of printed lots.
Availability of a single device to expose the image or design on both flat as well as rotary screens will provide financial and operational benefit to the end user. In place of buying two separate machines, uses need only one machine, hence a lesser space, one operator, a common machine control unit and a single uninterrupted power supply (UPS). Furthermore, making a multifunctional device has lot of impact on the conservation of natural resources and hence it provides sustainable technological solution.
The machine as per the present invention can be used for exposing both the flat screens and rotary screens for batch or mass printing using a single setup. Further, the said machine can be used for exposing the flat screens for textile sampling as well the rotary screens used for mass printing in a single setup. The said machine eliminates machine specific variations in the print quality on the flat and rotary screens, reduces machine cost, maintenance cost, labor cost and space required.
SUMMARY OF THE INVENTION
The present invention provides a machine for exposing designs on both flat and rotary screens permitting exposer of designs on the flat screens for textile sampling as well the rotary screens used for mass printing in a single setup eliminating machine specific variations and reducing screen geometry specific variations in the exposed designs on the flat and rotary screens, reduces machine cost, maintenance cost, labor cost and space required. Further, the present invention provides a machine for exposing designs on both flat and rotary for batch or mass printing using a single setup.
There is thus provided, in accordance with the present invention, a machine for exposing designs on both rotary and flat screens that overcomes the limitations of the prior art including a base frame assembly, a gantry mounted on the base frame assembly, an imaging device assembly mounted on the gantry, a print head mounted on the an imaging device assembly, a table fixed to the base frame assembly for mounting of a flat screens of different dimension, an arrangement for holding and supporting a rotary screens of different length and diameters, arrangement for measuring and controlling movement of the gantry along the x-axis, arrangement for measuring and controlling movement of the imaging device assembly along the y-axis, arrangement for measuring and controlling movement of the print head along the z-axis and arrangement for measuring and controlling angular rotation of the rotary screen with respect to the x-axis and y-axis position of the print head.
According to the present invention, a LASER sensor is provided to measure and set the distance of the print head from the flat screen and the rotary screen along the z-axis.
In the machine for exposing designs on both rotary and flat screens as per the present invention, the print head mounted on the imaging device assembly can be an Inkjet Print Head, a Light Emitting Diode (LED) Array arranged in one dimension (1D) or two dimension (2D), a Laser Diode Array arranged in 1D or 2D, or a micro mirror device in which tiny mirrors are arranged in 1D or 2D format which reflect light. Further, variety of the flat screen and the rotary screen are used corresponding to the type of print head.
Same print head is used for exposing design on both the flat screen and the rotary screen. The rotary encoder for measuring and controlling angular position of the rotary screen with respect to position of the print head and the rotary screen drive is capable of giving the incremental rotation resulting into circumferential travel distance of 1 pixel or less for all possible rotary screen diameters. The linear encoder used for measuring and controlling position of the print head along the x-axis and a servo motor for movement of the gantry (3) along the x-axis are selected such that they are capable of giving the incremental linear movement of 1 pixel or less in the direction along the x-axis. The linear encoder for measuring and controlling position of the print head along the y-axis and the linear motor drive for movement of the imaging device assembly along the y-axis are selected such that they are capable of giving the incremental linear movement of 1 pixel or less in the direction along the y-axis (9). This results into elimination of variation in the similar designs exposed on the flat screen and the rotary screen due to machine specification and screen geometry.
Further, there is also provided a method for exposing of a digital image having “m by n” pixel size using a print head of “p by q” pixel size on the flat screen and the rotary screen using the machine for exposing designs on both rotary and flat screens as per the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the invention as per the present patent application are described with reference to the following drawings in which like elements are labeled similarly. The present invention will be more clearly understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is a schematic diagram showing an isometric view of a machine for exposing designs on both rotary and flat screens (1) as per the present invention.
FIG. 2 is a schematic diagram showing a perspective view of a machine for exposing designs on both rotary and flat screens (1) along with x, y and z axis as per the present invention.
FIG. 3 is a schematic diagram showing a print head assembly (4) mounted on the gantry (3)
FIG. 4 is a schematic diagram showing a rotary screen mounted on a fix rotary screen holding support (6) and a movable rotary screen holding support (7) using screen holding attachments (19, 20).
FIG. 5 is a schematic diagram showing a center of the print head, a centerline of the rotary screen and area of projection of the image on the flat screen (11) and the rotary screen (12) for the print head (16) of size “p by q” pixel
FIG. 6 is a flow diagram showing steps for printing on the flat screen (11) using a machine for exposing designs on both rotary and flat screens (1).
FIG. 7 is a flow diagram showing steps for printing on the rotary screen (12) using a machine for exposing designs on both rotary and flat screens (1).
List of designations/ reference numbers in figure
1. a rotary and flat screen exposing machine
2. a base frame assembly
3. a gantry
4. an imaging device assembly
5. a table
6. a fix rotary screen holding support
7. a movable rotary screen holding support
8. an x-axis
9. a y-axis
10. a z-axis
11. a flat screen
12. a rotary screen
13. a front support member
14. a rotary screen drive
15. a linear guide system
16. a print head
18. a locking mechanism
19. a screen holding attachment
20. a screen holding attachment
21. an air pipe
22. a hollow cylindrical space of the rotary screen (12)
23. a rotary encoder
24. a servo motor
25. a linear motor drive
26. a motor
27. a LASER distance sensor
28. a linear encoder
29. a linear encoder
30. x-axis limit switches
31. y-axis limit switches
32. a home position sensor
33. a center of the print head (16)
34. a centerline of the rotary screen (12)
35. a motor
36. a gear box
37. a coupling
38. a gear box
39. a pinion gear
40. a rack
41. a lead screw
42. a rotary screen holding assembly
DETAILED DESCRIPTION OF THE INVENTION
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
The description of illustrative embodiments according to principles of the present invention is intended to be read in connection with the accompanying drawings, which are to be considered as a part of the entire written description. In the description of embodiments of the invention disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms and directives thereof are for convenience of description only and do not require that the apparatus be constructed or operated in a particular manner unless explicitly indicated as such. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Moreover, the features and benefits of the invention are illustrated by reference to the exemplified embodiments. Accordingly, the invention expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features; the scope of the invention being defined by the claims appended hereto. In the detail description the “said machine” means machine for exposing designs on both rotary and flat screens (1) as per the present invention.
FIG. 1 shows an isometric view of a machine for exposing designs on both rotary and flat screens (1) as per the present invention. FIG. 2 shows a perspective view of the machine for exposing designs on both rotary and flat screens (1) along with directions along an x-axis (8), a y-axis (9) and a z-axis (10) as per the present invention. As shown in FIG. 1-2, the machine for exposing designs on both rotary and flat screens (1) as per the present invention is consisting of a base frame assembly (2) on which all other parts of the said machine (1) are mounted, a gantry (3) mounted on the base frame assembly (2) and configured to move in a direction along the x-axis (8), an imaging device assembly (4) mounted on the gantry (3) and configured to move in a direction along the y-axis (9), a print head (16) mounted on the imaging device assembly (4) and configured to move in a direction along the z-axis (10), a table (5) fixed to the base frame assembly (2) for mounting of a flat screen (11), a fix rotary screen holding support (6) fitted on a front support member (13) of the base frame assembly (2) for mounting and holding a rotary screen (12) using a screen holding attachment (19) and, a movable rotary screen holding support (7) mounted on a linear guide system (15) provided on the front support member (13) of the base frame assembly (2) for holding and supporting the rotary screen (12) using a screen holding attachment (20).
As shown in FIG. 4, a rotary screen drive (14) is fitted on the fix rotary screen holding support (6) to rotate the screen holding attachment (19) and hence the rotary screen (12). The rotary screen drive (14) is consisting of a motor (35) coupled with a gear box (36). The screen holding attachment (19) is coupled with the gear box (36) using a coupling (37). The screen holding attachment (19) is supported on the fix rotary screen holding support (6) using a bearing. A rotary encoder (23) is attached to the output shaft of the gear box (36) for measuring and controlling an angular rotation of the screen holding attachment (19) and hence the rotary screen (12) with respect to position of the print head (16).
As shown in FIG. 2 and FIG. 4, the movable rotary screen holding support (7) is configured to slide over the linear guide system (15) and locked into desired position using a locking mechanism (18). The movable rotary screen holding support (7) is slide over the linear guide system (15) manually of automatically. This facilitates supporting and holding of the rotary screen (12) of different length.
The screen holding attachment (20) is supported on the movable rotary screen holding support (7) using a bearing, is free to rotate on the movable rotary screen holding support (7) and it moves along with the movable rotary screen holding support (7) in direction along the x-axis (8) to accommodate, support and hold the rotary screen (12) of different length. Length and diameter of the rotary screen (12) is dependent on the width of the fabric to be printed and dimension of a block of design to be repeated. The screen holding attachments (19, 20) can be replaced in a pair to hold and support the rotary screen (12) of different diameter.
The gantry (3) is extended along the y-axis (9) over the base frame assembly (2). This allows movement of the imaging device assembly (4) in the direction along the y-axis (9) for engraving over the rotary screen (12) mounted on the rotary screen holding attachments (19, 20).
Maintenance of the cylindrical shape of the rotary screen (12) is crucial for accurate exposer of the design on it. For this purpose, as shown in FIG. 4, an air pipe (21) is attached to the screen holding attachment (20). Pressurized air is supplied through this air pipe (21) inside a hollow cylindrical space (22) of the rotary screen (12) fitted on the screen holding attachments (19, 20) when exposing on the rotary screen (12) is in progress.
As shown in FIG. 2, two servo motors (24) are fitted on the gantry (3) and configured to move the gantry (3) along an x-axis (8). As shown in FIG. 3, each servo motor (24) is coupled with a gear box (38) having a pinion gear (39) mounted on its output shaft. A rack (40) is provided on the base frame assembly to form the rack (40) and the pinion gear (39) pair for linear movement of the gantry (3) in the direction along the x-axis (8). As shown in FIG. 3, a linear motor drive (25) is fitted on the gantry (3) and configured to move the imaging device assembly (4) in a direction along the y-axis (9). Hence, by using a combine movement in the direction along x-axis (8) and the y-axis (9), the imaging device assembly (4) can be located at any required (x, y) coordinate on the flat screen (11) mounted on the table (5) as well as the rotary screen (12) mounted on the screen holding attachments (19, 20). As shown in FIG. 3, a motor (26) is fitted on the imaging device assembly (4) and configured to move the print head (16) in a direction along the z-axis (10) using a lead screw (41) for setting the z-distance of the print head (16) from the flat screen (11) and the rotary screed (12) as per requirement. A LASER distance sensor (27) is attached to the print head (16) for measuring the distance of the print head (16) from the flat screen (11) and the rotary screed (12). An output of the LASER distance sensor (27) can be synchronized with the motor (26) using appropriate means for automatic setting of the z-distance of the print head (16).
For safety purpose and preventing damage to the various parts of the said machine (1) and the flat screen (11) and the rotary screen (12) mounted on the machine, x-axis limit switches (30) and y-axis limit switches (31) are provided. As shown in FIG. 2, the x-axis limit switches (30) are mounted on the base frame assembly (2) for limiting movement of the gantry (3) in the direction along the x-axis (8). As shown in FIG. 3, the y-axis limit switches (31) are mounted on the gantry (3) for limiting movement of the imaging device assembly (4) in the direction along the y-axis (9).
As shown in FIG. 3, a home position sensor (32) is mounted on the gantry (3). It helps in setting and sensing a machine zero position of the print head (16). This position is used as a reference for controlling automatic movement of the print head in the direction along the x-axis (8) and the y-axis (9) by establishing its relationship with the image coordinate [0, 0] (i.e. 0 pixel as an x-coordinate and 0 pixel as a y-coordinate).
For accuracy of design exposed on the flat screen (11), it is necessary to accurately measure and control the position and movement of the print head (16) in the directions along the x-axis (8) and the y-axis (9).
As shown in FIG. 3, a linear encoder (29) is mounted on the gantry (3) and configured for measuring and controlling position of the print head (16) along the y-axis (9). As shown in FIG. 2, a linear encoder (28) is mounted on the base frame assembly (2) and configured for measuring and controlling position of the print head (16) along the x-axis (8).
For accuracy of design exposed on the rotary screen (12), it is necessary to accurately measure and control the position and movement of the print head (16) in the directions along the x-axis (8) and the y-axis (9) and, angular position of the rotary screen (12) with respect to the position of the print head (16). For the purpose, as shown in FIG. 4, the rotary encoder (23) is attached to the rotary screen drive (14) for measuring and controlling angular position of the rotary screen (12) with respect to position of the print head (16).
Printing, exposing, engraving and projecting words are used interchangeably to represent printing of, exposing of, engraving of and projection of digital design or image on the flat and or rotary screen using the said machine (1). Present invention is concerned with the use of photolithography for exposing pattern for screen printing, flexo printing, offset printing, gravure printing and mainly relevant to screen printing. The photoresist developer used as per the present invention is water.
Following explanation discuss the procedural steps for printing or exposing of digital design or image of pixel size “m by n” using a print head (16) of size “p by q” on the flat screen (11) using the said machine (1). Here, m, n, p and q are positive integer numbers. As an example, when m and n is equal to 1000, image is of size 1000 pixel by 1000 pixel. However, m and n can also be different positive integers. When, p and q is equal to 10, the print head (16) is of size 10 pixel by 10 pixels. However, p and q can also be different positive integers. FIG. 6 is a flow diagram showing steps for printing on the flat screen (11) using a machine for exposing designs on both rotary and flat screens (1).
The flat screen (11) is coated with an Ultraviolet (UV) curable chemical. The flat screen (11) is then mounted on the table (5) fixed to the base frame assembly (2). First of all load “p by q” pixel grid from image coordinate [0, 0] (i.e. x coordinate is zero pixel and y coordinate is zero pixel) to the print head (16) which projects this image to the flat screen (11). Then move the print head (16) by 1 pixel in direction along the y-axis (9) and again load “p by q” pixel grid from image coordinate [0, 1] to the print head (16) which projects this image to the flat screen (11). Repeat the incremental movement of the print head (16) in direction along the y-axis (9) by 1 pixel to load “p by q” pixel grid from image coordinate up to [0, n] to the print head (16) which projects this image to the flat screen (11). Then move the print head (16) by p pixel in direction along the x-axis (8) and load “p by q” pixel grid from image coordinate [p, 0] to the print head (16) which projects this image to the flat screen (11). Then move the print head (16) by 1 pixel in direction along the y-axis (9) and again load “p by q” pixel grid from image coordinate [p, 1] to the print head (16) which projects this image to the flat screen (11). Repeat the incremental movement of the print head (16) by 1 pixel in direction along the y-axis (9) to load “p by q” pixel grid from image coordinate up to [p, n] to the print head (16) which projects this image to the flat screen (11). Repeat the incremental movement of the print head (16) by 1 pixel in the direction along the y-axis (9) and by p pixel in direction along x-axis (8) to load “p by q” pixel grid from image coordinate up to [m, n] to the print head (16) which projects this image to the flat screen (11) to project whole image on the flat screen (11).
Following explanation discuss the procedural steps for printing or exposing of digital design or image of pixel size “m by n” using a print head (16) of size “p by q” on the rotary screen (12) using the said machine (1). Here, m, n, p and q are positive integer numbers. As an example, when m and n is equal to 1000, image is of size 1000 pixel by 1000 pixel. When, p and q is equal to 10, the print head (16) is of size 10 pixel by 10 pixels. FIG. 7 is a flow diagram showing steps for printing on the rotary screen (12) using a machine for exposing designs on both rotary and flat screens (1).
The rotary screen (12) coated with an Ultraviolet (UV) curable chemical is mounted using the screen holding attachments (19, 20). As shown in FIG. 5, align a center (33) of the print head (16) with a centerline (34) of the rotary screen (12). The Rotary screen (12) is kept in continuous rotation mode during the whole exposure time using the rotary screen drive (14). Reading the image width ‘n’ in pixels, as this width ‘n’ in pixels needs to be exposed within the circumference of the rotary screen (12). Using the feedback from the rotary encoder (23) which gives ’R’ pulse per one rotation of the rotary screen (12), interpolate these ‘R’ pulses into the ‘n’ pulses. Load “p by q” pixel grid from image coordinate [0, 0] (i.e. x coordinate is zero pixel and y coordinate is zero pixel) to the print head (16) which projects this image to the rotary screen (12) when an interpolated pulse is received. Simultaneously, again load “p by q” pixel grid from image coordinate [0, 1] to the print head (16) which projects this image to the rotary screen (12) on receiving the next pulse, and continue this till all the n pulses are received. Then move the print head (16) by p pixel in direction along the x-axis (8) and load “p by q” pixel grid from image coordinate [p, 0] to the print head (16) which projects this image to the rotary screen (12). Simultaneously, again load “p by q” pixel grid from image coordinate [p, 1] to the print head (16) which projects this image to the rotary screen (12) on receiving the next pulse, and continue this till all the R pulses are received. Repeat the incremental rotary movement of the rotary screen (12) by 1 pixel and incremental linear movement of the print head (16) by p pixel in direction along the x-axis (8) to load “p by q” pixel grid from image coordinate up to [m, n] to the print head (16) which projects this image to the rotary screen (12) to project whole image on the rotary screen (12).
Here, the rotary encoder (23) attached to the rotary screen drive (14) for measuring and controlling angular position of the rotary screen (12) with respect to position of the print head (16) and the rotary screen drive (14) is selected such that it is capable of giving the incremental rotation resulting into circumferential travel distance of 1 pixel or less for all possible rotary screen (12) diameters.
The linear encoder (28) mounted on the base frame assembly (2) and configured for measuring and controlling position of the print head (16) along the x-axis (8) and a servo motor (24) fitted on the gantry (3) and configured to move the gantry (3) along an x-axis (8) are selected such that they are capable of giving the incremental linear movement of 1 pixel or less in the direction along the x-axis (8).
The linear encoder (29) mounted on the gantry (3) and configured for measuring and controlling position of the print head (16) along the y-axis (9) and the linear motor drive (25) fitted on the gantry (3) and configured to move the imaging device assembly (4) along a y-axis (9) are selected such that they are capable of giving the incremental linear movement of 1 pixel or less in the direction along the y-axis (9).
In the machine for exposing designs on both rotary and flat screens (1) as per the present invention the print head (16) mounted on the imaging device assembly (4) can be an Inkjet Print Head, a Light Emitting Diode (LED) Array arranged in one dimension (1D) or two dimension (2D), a Laser Diode Array arranged in 1D or 2D, or a micro mirror device in which tiny mirrors are arranged in 1D or 2D format which reflect light. Further, variety of the flat screen (11) and the rotary screen (12) are used corresponding to the type of print head (16).
In another embodiment of the present invention, the front support member (13) may not be a part of the base frame assembly (2). The fix rotary screen holding support (6) having the screen holding attachment (19) fitted on the front support member (13) and, the movable rotary screen holding support (7) having the screen holding attachment (20) mounted on the linear guide system (15) provided on the front support member (13) is considered as a rotary screen holding assembly (42). This rotary screen holding assembly (42) is than filleted on the base frame assembly (2). The rotary screen (12) is held and supported on the screen holding attachments (19, 20).
BEST METHOD OF PERFORMING THE INVENTI ON
A machine for exposing designs on both rotary and flat screens (1) and a method for exposing of a digital image having “m by n” pixel size using a print head of “p by q” pixel size on both the flat screen and the rotary screen using the said machine (1) is implemented with following specifications.
Imaging technology used: Digital Micromirror Device
Maximum Screen Size (flat screen): 3000 x 4000 (in mm x mm)
Maximum Screen Size (rotary screen): length- up to 3500 mm; circumference- 640 mm/ 820 mm/ 914 mm/ 1018 mm
Design file format: 1 Bit Tiff
Light Source: Integrated UV LED
UV wave length: 365-385 nm
Production speed: up to 200 square feet per hour
Ambient condition: 18-22 0C temperature, 40-60 % humidity
Input Power: 220 V/ 50 Hz ± 1 Hz , Claims:We claim:
1. A machine for exposing designs on both rotary and flat screens (1) comprising of:
a base frame assembly (2);
a gantry (3) mounted on the base frame assembly (2);
an imaging device assembly (4) mounted on the gantry (3);
a print head (16) mounted on the an imaging device assembly (4);
a table (5) fixed to the base frame assembly (2) for mounting of a flat screen (11);
a fix rotary screen holding support (6) fitted on a front support member (13) of the base frame assembly (2) for mounting and holding a rotary screen (12) using a screen holding attachment (19);
a movable rotary screen holding support (7) mounted on a linear guide system (15) provided on the front support member (13) of the base frame assembly (2) for holding and supporting the rotary screen (12) using a screen holding attachment (20);
a rotary screen drive (14) fitted on the fix rotary screen holding support (6) and configured to rotate the screen holding attachment (19) and hence the rotary screen (12);
a servo motor (24) fitted on the gantry (3) and configured to move the gantry (3) along an x-axis (8);
a linear motor drive (25) fitted on the gantry (3) and configured to move the imaging device assembly (4) along a y-axis (9);
a motor (26) fitted on the imaging device assembly (4) and configured to move the print head (16) along a z-axis (10);
x-axis limit switches (30) mounted on the base frame assembly (2) for limiting movement of the gantry (3) in the direction along the x-axis (8);
y-axis limit switches (31) mounted on the gantry (3) for limiting movement of the imaging device assembly (4) in the direction along the y-axis (9) and;
a home position sensor (32) mounted on the gantry (3) and configured for sensing home position of the print head (16);
Characterized in that wherein,
the gantry (3) is extended along the y-axis (9) over the base frame assembly (2) allowing the imaging device assembly (4) movement along the y-axis (9) for engraving over the rotary screen (12) mounted on the rotary screen holding attachments (19, 20),
the movable rotary screen holding support (7) is configured to slide over the linear guide system (15) manually or automatically and locked into desired position using a locking mechanism (18) to accommodate, support and hold the rotary screen (12) of different length,
the screen holding attachments (19, 20) can be configured to hold the rotary screen (12) of different diameters,
an air pipe (21) is attached to the screen holding attachment (20) and configured to supply pressurized air inside a hollow cylindrical space (22) of the rotary screen (12) fitted on the screen holding attachments (19, 20) to maintain the cylinder shape of the rotary screen (12),
a rotary encoder (23) is attached to the rotary screen drive (14) for measuring and controlling angular position of the rotary screen (12) with respect to position of the print head (16),
a LASER distance sensor (27) is attached to the print head (16) for measuring and setting the distance of the print head (16) with respect to the flat screen (11) and the rotary screen (12),
a linear encoder (29) is mounted on the gantry (3) and configured for measuring and controlling position of the print head (16) along the y-axis (9),
a linear encoder (28) is mounted on the base frame assembly (2) and configured for measuring and controlling position of the print head (16) along the x-axis (8),
for printing on the flat screen (11) using the said machine (1):
• the flat screen (11) coated with an Ultraviolet (UV) curable chemical is mounted on the table (5) fixed to the base frame assembly (2),
• followed by adjusting the distance of the print head (16) from the rotary screen (12) along the z-axis (10),
• if image is of “m by n” pixel and the print head (16) is of “p by q” pixel where m, n, p and q is some positive integer then first of all load “p by q” pixel grid from image coordinate [0, 0] (i.e. x coordinate is zero pixel and y coordinate is zero pixel) to the print head (16) which projects this image to the flat screen (11),
• move the print head (16) by 1 pixel in direction along the y-axis (9) and again load “p by q” pixel grid from image coordinate [0, 1] to the print head (16) which projects this image to the flat screen (11),
• repeat the incremental movement of the print head (16) in direction along the y-axis (9) by 1 pixel to load “p by q” pixel grid from image coordinate up to [0, n] to the print head (16) which projects this image to the flat screen (11),
• then move the print head (16) by p pixel in direction along the x-axis (8) and load “p by q” pixel grid from image coordinate [p, 0] to the print head (16) which projects this image to the flat screen (11),
• move the print head (16) by 1 pixel in direction along the y-axis (9) and again load “p by q” pixel grid from image coordinate [p, 1] to the print head (16) which projects this image to the flat screen (11),
• repeat the incremental movement of the print head (16) by 1 pixel in direction along the y-axis (9) to load “p by q” pixel grid from image coordinate up to [p, n] to the print head (16) which projects this image to the flat screen (11),
• repeat the incremental movement of the print head (16) by 1 pixel in the direction along the y-axis (9) and by p pixel in direction along x-axis (8) to load “p by q” pixel grid from image coordinate up to [m, n] to the print head (16) which projects this image to the flat screen (11) to project whole image on the flat screen (11),
for printing on the rotary screen (12) using the said machine (1):
• the rotary screen (12) coated with an Ultraviolet (UV) curable chemical is mounted using the screen holding attachments (19, 20),
• followed by aligning a centre (33) of the print head (16) with a centreline (34) of the rotary screen (12) and adjusting the distance of the print head (16) from the rotary screen (12) along the z-axis (10),
• the Rotary screen (12) is kept in continuous rotation mode during the whole exposure time using the rotary screen drive (14),
• reading the image width ‘n’ in pixels, as this width ‘n’ in pixels needs to be exposed within the circumference of the rotary screen (12),
• using the feedback from the rotary encoder (23) which gives ’R’ pulse per one rotation of the rotary screen (12),
• interpolating these ‘R’ pulses into the ‘n’ pulses,
• if image is of “m by n” pixel and the print head (16) is of “p by q” pixel where m, n , p and q are some positive integer then first of all load “p by q” pixel grid from image coordinate [0, 0] (i.e. x coordinate is zero pixel and y coordinate is zero pixel) to the print head (16) which projects this image to the rotary screen (12) when an interpolated pulse is received,
• simultaneously, again load “p by q” pixel grid from image coordinate [0, 1] to the print head (16) which projects this image to the rotary screen (12) on receiving the next pulse,
• continue this till all the n pulses are received,
• then move the print head (16) by p pixel in direction along the x-axis (8) and load “p by q” pixel grid from image coordinate [p, 0] to the print head (16) which projects this image to the rotary screen (12),
• simultaneously, again load “p by q” pixel grid from image coordinate [p, 1] to the print head (16) which projects this image to the rotary screen (12) on receiving the next pulse,
• continue this till all the R pulses are received and,
• repeat the incremental rotary movement of the rotary screen (12) by 1 pixel and incremental linear movement of the print head (16) by p pixel in direction along the x-axis (8) to load “p by q” pixel grid from image coordinate up to [m, n] to the print head (16) which projects this image to the rotary screen (12) to project whole image on the rotary screen (12).
2. The machine for exposing designs on both rotary and flat screens (1) as claimed in claim 1, wherein the print head (16) mounted on the imaging device assembly (4) can be an Inkjet Print Head, a Light Emitting Diode (LED) Array arranged in one dimension (1D) or two dimension (2D), a Laser Diode Array arranged in 1D or 2D, or a micro mirror device in which tiny mirrors are arranged in 1D or 2D format which reflect light.
3. The machine for exposing designs on both rotary and flat screens (1) as claimed in claim 1, wherein the ‘m’ and ‘n’ can be same or different positive integers.
4. The machine for exposing designs on both rotary and flat screens (1) as claimed in claim 1, wherein the ‘p’ and ‘q’ can be same or different positive integers.
5. The machine for exposing designs on both rotary and flat screens (1) as claimed in claim 1, wherein the linear encoder (28) mounted on the base frame assembly (2) and configured for measuring and controlling position of the print head (16) along the x-axis (8) and the servo motor (24) fitted on the gantry (3) and configured to move the gantry (3) along the x-axis (8) are selected such that they are capable of giving the minimum incremental linear movement of 1 pixel in the direction along the x-axis (8).
6. The machine for exposing designs on both rotary and flat screens (1) as claimed in claim 1, wherein the linear encoder (29) mounted on the gantry (3) and configured for measuring and controlling position of the print head (16) along the y-axis (9) and the linear motor drive (25) fitted on the gantry (3) and configured to move the imaging device assembly (4) along the y-axis (9) are selected such that they are capable of giving the minimum incremental linear movement of 1 pixel in the direction along the y-axis (9).
7. The machine for exposing designs on both rotary and flat screens (1) as claimed in claim 1, wherein the rotary encoder (23) attached to the rotary screen drive (14) for measuring and controlling angular position of the rotary screen (12) with respect to position of the print head (16) and the rotary screen drive (14) is selected such that it is capable of giving the incremental rotation resulting into a circumferential minimum travel distance of 1 pixel for all possible rotary screen (12) diameters.
8. The machine for exposing designs on both rotary and flat screens (1) as claimed in claim 1, the front support member may not be a part of the base frame assembly (2) instead, the fix rotary screen holding support (6) having the screen holding attachment (19) fitted on the front support member (13) and, the movable rotary screen holding support (7) having the screen holding attachment (20) mounted on the linear guide system (15) provided on the front support member (13) is considered as a rotary screen holding assembly (42) where the rotary screen holding assembly (42) is fitted on the base frame assembly (2) and the rotary screen (12) is held and supported on the screen holding attachments (19, 20).