FIELD OF THE INVENTION
[0001] The present invention, in general, relates to methods for detecting the formation of dough ball in a flour mixing and kneading apparatus. Particularly, it relates to an optical method to detect various stages leading to achieving desired consistency of dough, and the formation of dough ball in the mixer apparatus. More particularly, the invention relates to an optical method wherein the interruptions caused by the revolving flour particles and its changing physical form affects the intensity of a light beam, wherein the variations in light intensity is interpreted and mapped to track and control the different stages in the process.
DESCRIPTION OF PRIOR ART
[0002] US Pat No. 7168362 teaches a bread maker and control method thereof, wherein it features a disk sensor emitting a light toward the disk part and outputting a pulse signal according to interruption of the light by rotation of the at least one projection of the disk part. However, the light sensing is used for sensing rotation and not consistency or dough ball formation.
[0003] Patent publication US20110174169 A1 teaches a bread maker featuring a rise detector that receives light from a light-emitting element using a light-receiving element, detects that dough exceeds the prescribed height from an upper surface of the container on the basis of a change in a light receiving state. But said system does not control the various stages of its operations based on the perceived

variation in the intensity of light. Light beam is used only to detect the rising of dough.
[0004] CN1256060 C teaches a bread machine and its controlling method wherein the apparatus features a circular plate sensor that outputs a signal when the light from a light source is interrupted. However interruption of light beam is used only for rotation sensing, and not for detection of dough properties.
[0005] Our invention, on the other hand, proposes an apparatus that has the following advantages compared to the inventions mentioned in this section.
• A light beam is used to sense the presence of flour, as it obstructs the light.
• The variations in the intensity of light during mixing are used to detect various stages in mixing.
• The variations in the intensity of light during mixing are used to control the dosing of ingredients during mixing.
• The variations in the intensity of light are used to detect the formation of dough ball.
• The variations in the intensity of light is used to detect the presence of multiple dough balls, or incorrect dough ball formation, and take corrective actions resulting in the formation of a dough ball.
• The variations in the intensity of light are used to detect failure in dough ball formation, which is then used to request user intervention.

SUMMARY OF THE INVENTION
[0006] The patent presents a novel method to detect by optical means, optimal dough consistency and dough ball formation in a mixing and kneading apparatus wherein flour is mixed with ingredients, typically liquid, to form a mix that is typically lumped together at the end of mixing or kneading, in a roughly spherical shape. The invention describes how the interruptions caused by the revolving flour and its changing physical form affect the intensity of a light beam as measured by a light sensor. On the basis of said variation in light intensity, methods to interpret and map the patterns of variation in light intensity to different stages in mixing/kneading are presented.
[0007] It is therefore the primary objective of the invention is to propose a method to detect by optical means the various stages in the process of formation of dough ball with optimal consistency as a result of mixing and kneading process in the mixer.
[0008] It is another object of the invention to propose a method that is independent of current consumed by the mixer motor.
[0009] It is yet another object of the invention to provide an efficient method to detect the dough formation process in the mixer, with the desired consistency.
[0010] The other objectives, features, and advantages of the present invention will become more apparent from the ensuing detailed description of the invention, taken in conjunction with the accompanying drawings.

DESCRIPTION OF ACCOMPANYING FIGURES
[0011] FIG.1 shows the mixer.
[0012] FIG.2 illustrates the positions of light sensor and light source.
[0013] FIG.3 depicts the mixing stages flowchart.
[0014] FIG.4 shows the patterns of variation in light intensity during the third and fourth stages of mixing.

DETAILED DESCRIPTION OF THE INVENTION
[0015] The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However, in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention.
[0016] In the rest of this document, mixer refers to the mixing and kneading apparatus, as referred to in PCT publication WO2016088136. The mixer is made from a material that is either transparent or translucent. FIG.1 illustrates the mixer, wherein it features a mixer bowl (b), inside which a rotating mixing element (n) is placed. The ingredients are dosed into the mixer via the opening on the top of the mixer chute (a) and the desired result after mixing and shaping is a dough ball (w) of good consistency and shape.
[0017] The light sensor and light source are positioned in a manner that maximum light falls on the light sensor when the mixer is empty, and minimum light falls on the sensor when the mixer is filled with sufficient flour to make a dough ball. In a typical configuration of the mixer as shown in FIG.2, the light source (e) and sensor (d) are

placed along a line that passes between the shaft of the mixing element (n) and the inner walls of the mixer bowl (b).
[0018] To minimise the effect of ambient light, the light sensor is optionally enclosed in a tube. In another embodiment, the light source is tuned to a specific frequency and the sensor is adapted to provide intensity data at that particular frequency. In yet another embodiment, a laser beam is used. Though the disclosed mixer employs only a single light source and single light sensor, it is also possible to use multiple emitters and detectors, placed at various positions that allow monitoring the changes taking place in the ingredients, and this is included in the scope of this disclosure. Suitable methods maybe employed to combine data from a set of those sensors and to activate a set of such light sources. These sensors and sources may be of the same or of varied types.
[0019] The operation of the mixer is classified into multiple stages to explain the method disclosed by the present invention. FIG.3 illustrates different stages of the system, which are described in the following paragraphs.
[0020] In the first stage, flour is dosed into the mixer through the opening at the top of the mixer chute (a) shown in FIG.1, wherein said flour obstructs the light falling on the sensor. As a result, the light intensity drops, and falls below a certain threshold T1. The optical detection system flags this stage as Stagel based on this reduction in light intensity.
[0021] In the second stage, dosing of water is performed. Mixing also starts during

this stage. Optionally, this stage can overlap with Stage 1, wherein both flour and water are dosed simultaneously. In a typical scenario, mixing starts along with dosing of water. Due to the mixing of water and flour, the flour particles become sticky, and start to cling together to form granules. Stage 2 comes to an end when a fixed quantity of water has been dosed at a relatively higher rate of flow, compared to the next stages.
[0022] The quantity of water dosed in Stage 2 is such that it allows for a certain amount of water to be dosed in the third stage, so that the desired consistency is achieved by a sufficiently long mixing time. This also allows for the desired consistency to be achieved in Stage 3 by monitoring the variations in light intensity as water is dosed at a relatively lower rate of flow. The quantity of water dosed in Stage 2 is also high enough to reduce the time of mixing by dosing most of the required quantity of water upfront. This quantity may optionally be adapted dynamically on each mixing cycle, based on different parameters measured during mixing like the variation in light intensity, current consumption of the motor, total amount of water consumed, time taken for mixing and the like.
[0023] In Stage 3, along with mixing, dosing of water continues, typically at a lower rate of flow. The granules formed by the flour are thrown around within the mixer by the action of the mixing element, and interrupt the light falling on the sensor (d) shown in FIG.2. The light passes through the tiny gaps in this cloud of particles that are thrown around, resulting in an overall increase in the recorded light intensity. At a more detailed level, the light intensity rises and falls in a wavy manner as shown in FIG.4. Continued mixing results in the granules becoming larger compared to Stage
Q

2. As a result, the light intensity now shows a larger variation. Once this variation crosses threshold T3 as illustrated in FIG.4, the dosing of water is reduced or stopped. Mixing continues. This is the end of Stage 3.
[0024] In Stage 4, the dosing of water is either stopped or continued at a low rate of flow. Mixing continues and the granules form lumps. At this stage, the difference between peaks and troughs of light intensity increases, as illustrated in FIG.4. Eventually the mix forms a single dough ball, wherein the maximum variations in light intensity are observed. As mixing continues and the dough ball rotates about the mixing element, a rhythmic wavy pattern is observed in the light intensity. The following conditions are checked to flag the end of Stage 4:
• The maximum variation, that is the difference between the peaks and troughs of the light intensity, crosses a preset or dynamic threshold.
• There are a certain minimum number of peaks per preset or dynamic time . interval.
• The above conditions should be met within a preset or dynamic timeout.
Once said conditions are successfully met, the end of Stage 4 is signalled. At said
stage, a dough ball of optimal consistency is obtained. If these conditions are not
met, the system goes to Stage 5. If these conditions are met, which is the successful
completion of Stage 4, the system goes to Stage 6.
[0025] In Stage 5, the granules aggregate to form multiple lumps that fail to form a single dough ball, and the system detects it using the conditions checked for in Stage 4. Stage 5 is a correction stage that is reached if Stage 4 by itself does not

produce a single well formed dough ball. The correction is done by dosing water at a low rate of flow, and continuing mixing, optionally at varying speeds or intermittent mixing. Typically this causes the multiple lumps to join together and form a single dough ball. If this does not happen within a certain period of time, or until a certain amount of water is dosed, the system moves to Stage 6 wherein user intervention is required to clean the mixer and start it again from Stage 1.
[0026] In Stage 7, the mixer contains a single well formed dough ball, and is ready and waiting for subsequent steps like coating with other ingredients or transfer to the next stage.
[0027] Though the methods presented are in the context of an autonomous mixing system as described in WO2016088136, they could be used in other applications also, and are covered within the scope of this patent.
[0028] The values, numbers, positions and configurations presented are for illustration of the method, and could be changed to suit specific application by a person skilled in the art, and yet use the same methods presented. Such uses are also covered within the scope of this patent.
[0029] Although the present invention has been described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible, including applications in fields other than food processing, and are apparent to those skilled in the art.

Such changes and modifications are to be understood as included within the scope of the present invention unless they depart there from.