Optical sorter

Abstract

To provide an optical sorter capable of more surely eliminating a coloring foreign object.SOLUTION: An optical sorter comprises: a chute; an imaging unit 2 that images an object flowing down from the chute; a detection unit 5 that detects the object to be eliminated on the basis of an image captured by the imaging unit 2; an injection unit 3 that injects prescribed injection time air to the object at prescribed injection timing; and an injection control unit 6 that controls the injection unit 3. The detection unit 5 includes a color determination part 50, a measurement part 51, and a determination part 52 that determines that the object is a coloring foreign object when a determination condition is satisfied, and determines that the object is a damaged grain or a coloring grain when the determination condition is not satisfied. The injection control unit 6 sets, when the determination unit 52 determines that the object is the coloring foreign object, the injection timing for the object to coloring foreign object timing later than rice grain timing for the damaged grain and coloring grain.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an optical sorter for sorting granular objects. [Background technology]

[0002] A sorting machine for sorting granular objects is known that includes a jet nozzle means for jetting defective products, an optical detection means such as a visible light sensor or a near-infrared light sensor, and a comparison unit for determining whether colored particles and foreign matter are good or bad based on the output signal of the optical detection means, and jets the colored particles and foreign matter from the jet nozzle means at different jet times and delay times (see, for example, Patent Document 1).A similar sorting machine is also known that distinguishes between good and bad products based on the image pickup signal of an image pickup means such as a CCD camera (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-179292 [Patent Document 2] JP 2021-079343 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, examples of colored foreign matter that may be mixed into rice, wheat, and other grains include pumice, plastic fragments, and seeds of Aeschynomena genus of the legume family. In particular, Aeschynomena seeds have a black or dark brown colored area, similar to damaged grains such as diseased grains, insect-damaged grains, brown rice, and spotted grains, as well as colored grains, so it may be difficult to distinguish Aeschynomena seeds from damaged grains and colored grains. For this reason, there has been a demand for a technology that can more reliably distinguish colored foreign matter that does not include rice grains, such as Aeschynomena seeds, from damaged grains and colored grains, and more reliably remove colored foreign matter.

[0005] The present invention has been made in view of the above, and has an object to provide an optical sorting machine that can more reliably remove colored foreign matter. [Means for solving the problem]

[0006] The optical sorting machine of the present invention is an optical sorting machine that sorts granular objects, and includes a chute through which the objects flow down, an imaging unit that images the objects flowing down from the chute, a detection unit that detects objects to be removed from the objects based on an image of the objects captured by the imaging unit, an injection unit that injects air at the objects to be removed for a predetermined injection time at a predetermined injection timing so as to blow away the objects to be removed, and an injection control unit that controls the injection unit.

[0007] The detection unit has a color judgment unit that judges whether each of the objects is a reject object including a colored portion based on the image, a measurement unit that measures the size of the reject object judged by the color judgment unit to include the colored portion and the size of the colored portion, and a judgment unit that judges the reject object to be a colored foreign object when a judgment condition is satisfied that the size of the reject object measured by the measurement unit is equivalent to the size of the colored portion measured by the measurement unit and the size of the reject object is smaller than the size of a rice grain, and judges the reject object to be a damaged grain or a colored grain when the judgment condition is not satisfied. The injection control unit, when the judgment unit judges the reject object to be a colored foreign object, sets the injection timing for the reject object to a colored foreign object timing that is slower than the rice grain timing for the damaged grain and the colored grain.

[0008] According to the above configuration, first, the color judgment unit of the detection unit distinguishes between objects to be removed that include colored parts and objects to be removed that do not include colored parts. Objects to be removed that include colored parts include colored foreign matter such as pumice, plastic pieces, and aeschynomia seeds, as well as damaged grains and colored grains. Objects to be removed that do not include colored parts include rice grains.

[0009] Next, based on the size of the object to be excluded measured by the measuring unit and the size of the colored portion, the determining unit determines whether the object to be excluded is a colored foreign object, a damaged grain, or a colored grain. Specifically, by determining whether the size of the object to be excluded and the size of the colored portion are equivalent, damaged grains, colored grains, and colored foreign objects having a colored portion overall are distinguished from damaged grains and colored grains having a colored portion partially. In addition, by determining whether the size of the object to be excluded is smaller than the size of a rice grain, colored foreign objects are distinguished from damaged grains and colored grains having a colored portion overall.

[0010] That is, when the size of the object to be excluded measured by the measuring unit is equal to the size of the colored portion measured by the measuring unit and the size of the object to be excluded measured by the measuring unit is smaller than the size of a rice grain, the object to be excluded is determined to be a colored foreign matter. On the other hand, when the judgment condition is not satisfied, the object to be excluded is determined to be a damaged grain or a colored grain. By such a judgment process by the judging unit, it is possible to more reliably distinguish between colored foreign matter and damaged grains and colored grains.

[0011] Incidentally, pumice, plastic pieces, and aeschynomena seeds, which are given as examples of colored foreign matter, tend to be lighter than the damaged grains and colored grains. Therefore, the speed at which such colored foreign matter flows down the chute tends to be slower than the speed at which the damaged grains and colored grains flow down the chute. Therefore, such colored foreign matter tends to reach the injection position where air is injected by the injection unit later than the damaged grains and colored grains. In consideration of this point, when the judgment unit judges that the object to be removed is a colored foreign matter, the injection control unit sets the injection timing for the object to be removed to a colored foreign matter timing that is later than the rice grain timing for the damaged grains and colored grains. This makes it possible to more reliably blow away the colored foreign matter that tends to reach the injection position later than the damaged grains and colored grains, and therefore to more reliably remove the colored foreign matter.

[0012] In the above-mentioned optical sorting machine, the injection control unit may set the injection timing for the object to be excluded to the timing for colored foreign matter when the flow rate of the object flowing down from the chute is below a predetermined threshold value and when the judgment unit judges that the object to be excluded is a colored foreign matter.

[0013] When the flow rate of the object is relatively high, the objects have relatively high chances of coming into contact with each other, so that the colored foreign matter flowing down the chute may be swept away by the following damaged grains and rice grains, including colored grains, and may reach the injection position almost at the same time as the damaged grains and colored grains. Therefore, when the flow rate of the object is relatively high, it is assumed that the colored foreign matter will also be eliminated when the damaged grains and colored grains are blown away and eliminated at the timing for rice grains. On the other hand, when the flow rate of the object is relatively low, the objects have relatively low chances of coming into contact with each other, so that the colored foreign matter flowing down the chute is unlikely to be swept away by the following damaged grains and rice grains, including colored grains, and therefore the colored foreign matter is likely to reach the injection position later than the damaged grains and colored grains. Therefore, when the flow rate of the object is relatively low, there is a tendency for more colored foreign matter to be eliminated by injecting air at the timing for colored foreign matter, which is later than the timing for rice grains, compared to when the flow rate of the object is relatively high as described above. In this way, when the flow rate of the target substance is relatively low, the injection timing for the colored foreign matter is set to the timing for colored foreign matter, so that the colored foreign matter can be efficiently removed.

[0014] In the optical sorting machine, the measuring unit may measure the length of the longest line segment that can be drawn within the outline of the object to be excluded on the image as the size of the object to be excluded, and measure the length of the longest line segment that can be drawn within the outline of the colored portion as the size of the colored portion. This makes it possible to easily obtain the size of the object to be excluded and the size of the colored portion.

[0015] In the optical sorting machine described above, when the determining unit determines that the object to be removed is a colored foreign matter, the injection control unit may set the injection time for the object to be removed to a colored foreign matter injection time that is longer than the rice grain injection time for the damaged grains and the colored grains. This makes it possible to more reliably blow away the colored foreign matter even if an error occurs in the speed at which the colored foreign matter flows down the chute and the colored foreign matter flows further behind the damaged grains and the colored grains, and therefore makes it possible to more reliably remove the colored foreign matter. Effect of the Invention

[0016] As described above, according to the present invention, colored foreign matter can be more reliably removed. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of an optical sorting machine in a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of an image of an object captured by an imaging section; [Diagram 3] FIG. 2 is a block diagram showing a part of the configuration of a control system of the optical sorting machine in the first embodiment. [Figure 4] 4 is a flowchart showing an example of a sorting process by the optical sorting machine in the first embodiment. [Figure 5A] FIG. 13 is a diagram showing an example of a location measured by a measuring unit for damaged grains. [Figure 5B] FIG. 4 is a diagram showing an example of a location of a colored foreign substance measured by a measurement unit. [Figure 6] 6 is a diagram showing an example of injection timing by an injection unit. FIG. [Figure 7] 13A and 13B are diagrams for explaining modified examples of the injection time by the injection unit. [Figure 8] FIG. 11 is a block diagram showing a part of the configuration of a control system of an optical sorting machine in embodiment 2. [Figure 9] 11 is a flowchart showing an example of a sorting process by an optical sorting machine in the second embodiment. [Figure 10]1 is a graph showing an example of a change in flow rate of an object over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] (Embodiment 1) <Configuration of optical sorting machine> 1 is a schematic diagram showing the configuration of an optical sorting machine A in embodiment 1. First, the configuration of the optical sorting machine A in embodiment 1 of the present invention will be described.

[0020] The optical sorting machine A sorts granular objects Q. The objects Q are, for example, rice. The optical sorting machine A sorts the objects Q into retained objects to be kept and rejected objects Qr to be rejected. The retained objects are, for example, rice grains that meet certain inspection standards, and the rejected objects Qr are, for example, damaged grains, dead rice, discolored grains, immature grains, foreign objects, etc.

[0021] The optical sorting machine A is provided with a supply section 90 that supplies the object Q to the optical sorting machine A, and a recovery section 91 that recovers the object Q. The recovery section 91 includes a retained object recovery section 92 that recovers the retained object, and a removed object recovery section 93 that recovers the rejected object Qr. The thick solid arrow in FIG. 1 conceptually indicates the trajectory of the object Q flowing down from the chute 1, the thick dashed arrow in FIG. 1 conceptually indicates the trajectory of the retained object, and the thick dashed-dotted arrow in FIG. 1 conceptually indicates the trajectory of the rejected object Qr. A plurality of retained object recovery sections 92 and removed object recovery sections 93 may be provided depending on the types of the retained object and the rejected object Qr.

[0022] 1, the optical sorting machine A includes a chute 1, an imaging unit 2, an ejection unit 3, and a control device 4A. The chute 1 allows objects Q to flow down. The chute 1 is inclined with respect to a horizontal plane H.

[0023] FIG. 2 is a diagram showing an example of an image P of an object Q captured by the imaging unit 2. The imaging unit 2 captures an image of the object Q flowing down from the chute 1. The imaging unit 2 captures an image of the object Q at an imaging position Px on the trajectory of the object Q flowing down from the chute 1. The imaging unit 2 is configured, for example, using two line CCD sensors 2a and 2b arranged symmetrically across the chute 1, and two mirrors 20a and 20b that reflect light from the line CCD sensors 2a and 2b are arranged symmetrically across the chute 1 so that the line CCD sensors 2a and 2b can capture an image of the object Q at the imaging position Px. The imaging unit 2 generates an image P of the object Q as shown in FIG. 2. The imaging unit 2 may be configured using a CMOS sensor.

[0024] The ejection unit 3 ejects air at a predetermined ejection time at a predetermined ejection timing toward the object to be removed Qr so as to blow the object to be removed Qr away. The ejection unit 3 has an ejection port 30 that opens toward an ejection position Pj that is located below the imaging position Px of the imaging unit 2. The object to be removed Qr is blown away by the air from the ejection port 30 toward the removed object recovery unit 93 at the ejection position Pj.

[0025] 3 is a block diagram showing a part of the configuration of the control system of the optical sorting machine A in the embodiment 1. The control device 4A is configured using a processor and a memory. As shown in FIG. 3, the control device 4A includes a detection unit 5 and an injection control unit 6.

[0026] The detection unit 5 detects a removal target Qr from the object Q based on the image P of the object Q captured by the imaging unit 2. As shown in FIG. 3, the detection unit 5 has a color judgment unit 50, a measurement unit 51, and a judgment unit 52. The ejection control unit 6 controls the ejection unit 3. The processing by the detection unit 5 and the ejection control unit 6 will be described in detail later with reference to a flowchart. The detection unit 5 and the ejection control unit 6 may be provided in separate devices.

[0027] <Sorting process procedure> Fig. 4 is a flowchart showing an example of a sorting process by the optical sorting machine A in embodiment 1. Next, the procedure of the sorting process by the optical sorting machine A in embodiment 1 will be described with reference to the flowchart in Fig. 4. The sorting process shown in Fig. 4 is executed after the supply of objects Q to the optical sorting machine A is started.

[0028] First, in step SA1, the imaging unit 2 images an object Q flowing down from the chute 1 to generate an image P of the object Q. In step SA2, the detection unit 5 acquires the image P from the imaging unit 2.

[0029] Next, in steps SA3 to SA6, the detection unit 5 executes a detection process that includes colored foreign matter such as pumice, plastic pieces, and aeschynomena seeds, as well as damaged grains and colored grains as detection targets. Specifically, the process is as follows.

[0030] In step SA3, the color judgment section 50 of the detection unit 5 judges whether or not each object Q includes a colored portion α based on the image P. For example, when the color judgment section 50 detects pixels showing a predetermined object color in a pixel area corresponding to each object Q appearing in the image P, it judges that the object Q includes the colored portion α. ​​For example, if the object Q appearing in the image P is a Solanum edulis seed, pixels showing a black or dark brown color are detected. The processing in step SA3 is performed for each object Q appearing in the image P.

[0031] If it is determined in step SA3 that the object Q includes the colored portion α, the process proceeds to step SA4. For example, if the object Q is a diseased grain, an insect-damaged grain, a damaged grain such as brown rice or a spotted grain, a colored grain, or a colored foreign object, the object Q is determined to include the colored portion α, and the process proceeds to step SA4. On the other hand, if it is determined in step SA3 that the object Q does not include the colored portion α, the process proceeds to step SA10, where other sorting processes are performed, and then the process ends. For example, if the object Q is a grain simply having a shape abnormality such as a deformed grain or a broken grain, a dead grain, an immature grain, or a white grain, the object Q is determined to not include the colored portion α, and the process proceeds to step SA10. As described above, the object Q determined to include the colored portion α in step SA3 is uniformly a reject object Qr. For this reason, it can be said that in step SA3, the color determination unit 50 determines whether each object Q is a reject object Qr that includes the colored portion α among the reject objects Qr based on the image P.

[0032] FIG. 5A is a diagram showing an example of a portion measured by the measuring unit 51 in a damaged grain. FIG. 5B is a diagram showing an example of a portion measured by the measuring unit 51 in a colored foreign body. FIG. 5B shows an example of a portion measured in a seed of Aeschynomena japonica, which is an example of a colored foreign body. In step SA4, the measuring unit 51 of the detection unit 5 measures the size S1 of the object to be excluded Qr determined by the color judgment unit 50 to include a colored portion α, and the size S2 of the colored portion α. ​​Specifically, as shown in FIG. 5A and FIG. 5B, the measuring unit 51 measures the length of the longest line segment LS1 that can be drawn within the contour C1 of the object to be excluded Qr on the image P as the size S1 of the object to be excluded Qr, and measures the length of the longest line segment LS2 that can be drawn within the contour C2 of the colored portion α as the size S2 of the colored portion α. ​​This makes it easy to obtain the size S1 of the object to be excluded Qr and the size S2 of the colored portion α.

[0033] The measurement unit 51 may measure the area of ​​the region surrounded by the contour C1 of the object to be excluded Qr as the size S1 of the object to be excluded Qr, instead of the length of the longest line segment LS1, and may similarly measure the area of ​​the region surrounded by the contour C2 of the colored portion α as the size S2 of the colored portion α, instead of the length of the longest line segment LS2. In this way, the size S1 of the object to be excluded Qr and the size S2 of the colored portion α can be easily obtained.

[0034] 4, the judgment section 52 of the detection section 5 judges whether the object to be excluded Qr is a colored foreign matter, a damaged grain, or a colored grain based on the size S1 of the object to be excluded Qr and the size S2 of the colored portion α measured by the measurement section 51. More specifically, the judgment is as follows.

[0035] In step SA5, the determination unit 52 determines whether the size S1 of the object to be excluded Qr is equal to the size S2 of the colored portion α. ​​If it is determined that the size S1 of the object to be excluded Qr is equal to the size S2 of the colored portion α, the process proceeds to step SA6. For example, if the object to be excluded Qr is a damaged grain or a colored grain having the colored portion α as a whole, or a colored foreign matter as shown in FIG. 5B, it is determined that the size S1 of the object to be excluded Qr is equal to the size S2 of the colored portion α, and the process proceeds to step SA6. On the other hand, if it is determined that the size S1 of the object to be excluded Qr is not equal to the size S2 of the colored portion α, the process proceeds to step SA8. For example, if the object to be excluded Qr is a colored grain having the colored portion α partially, or a damaged grain as shown in FIG. 5A, it is determined that the size S1 of the object to be excluded Qr is not equal to the size S2 of the colored portion α, and the process proceeds to step SA8. That is, in step SA5, the damaged grains, colored grains, and colored foreign matter having the colored portion α as a whole are distinguished from the damaged grains and colored grains having the colored portion α partially.

[0036] In step SA6, the determination unit 52 determines whether the size S1 of the object to be excluded Qr is smaller than the size of a rice grain. The size of the rice grain is, for example, a standard size of a rice grain, and is stored in advance as a numerical value in the control device 4A. If it is determined that the size S1 of the object to be excluded Qr is smaller than the size of a rice grain, the process proceeds to step SA7. For example, if the object to be excluded Qr is a pumice stone, a plastic piece, or a seed of a grass family, the process proceeds to step SA7. On the other hand, if it is determined that the size S1 of the object to be excluded Qr is not smaller than the size of a rice grain, the process proceeds to step SA8. For example, if the object to be excluded Qr is a damaged grain or a colored grain having a colored portion α as a whole, the process proceeds to step SA8. That is, in step SA6, a colored foreign object is distinguished from a damaged grain and a colored grain having a colored portion α as a whole.

[0037] To summarize the above steps SA5 to SA6, the determination unit 52 determines that the object to be excluded Qr is a colored foreign object when the size S1 of the object to be excluded Qr measured by the measurement unit 51 is equal to the size S2 of the colored portion α measured by the measurement unit 51 and the size S1 of the object to be excluded Qr is smaller than the size of a rice grain, and when the determination condition is not satisfied, the determination unit 52 determines that the object to be excluded Qr is a damaged grain or a colored grain. By such a determination process by the determination unit 52, it is possible to more reliably distinguish between colored foreign objects and damaged grains and colored grains. When the above steps SA3 to SA6 are passed and step SA7 is reached, the detection result by the detection unit 5 is "colored foreign object," and when step SA8 is reached, the detection result by the detection unit 5 is "damaged grain or colored grain."

[0038] The order of steps SA5 and SA6 may be reversed. Even in this case, by performing the processing in step SA5 after the processing in step SA6, even if the objects to be removed Qr are damaged grains and colored grains partially having a colored portion α and are relatively small, such damaged grains and colored grains can be reliably distinguished from colored foreign matter in the same manner as described above.

[0039] If the determination unit 52 determines that the object to be excluded Qr is a damaged grain or a colored grain, the injection control unit 6 sets the injection timing for the object to be excluded Qr to the rice grain timing Tr for damaged grains and colored grains in step SA8 shown in FIG. 4. On the other hand, if the determination unit 52 determines that the object to be excluded Qr is a colored foreign matter, the injection control unit 6 sets the injection timing for the object to be excluded Qr to the colored foreign matter timing Tk in step SA7. Then, in step SA9, the injection unit 3 injects air onto the object to be excluded Qr at the injection timing set by the injection control unit 6. The processes from step SA4 to step SA9 are performed for each object to be excluded Qr determined in step SA3 to include a colored portion α.

[0040] Fig. 6 is a diagram showing an example of the injection timing by the injection unit 3. The upper part of Fig. 6 shows an example of the relationship between time (horizontal axis) and the positions (vertical axis) of colored foreign matter and damaged grains and colored grains, the middle part of Fig. 6 shows a timing chart of the detection process by the detection unit 5, and the lower part of Fig. 6 shows a timing chart of the injection by the injection unit 3.

[0041] Next, the injection timing and injection time by the injection unit 3 will be described in detail. As shown in the lower part of Fig. 6, the injection of air by the injection unit 3 against the damaged grains and colored grains starts at the rice grain timing Tr and ends at the end timing T1, which is a time J after the rice grain timing Tr. In this embodiment, the rice grain timing Tr is set before the damaged grains and colored grains reach the injection position Pj. Similarly, the injection of air by the injection unit 3 against the colored foreign matter starts at the colored foreign matter timing Tk and ends at the end timing T2, which is a time J after the colored foreign matter timing Tk. In this embodiment, the colored foreign matter timing Tk is set before the colored foreign matter reaches the injection position Pj.

[0042] Incidentally, pumice, plastic pieces, and aeschynomena seeds, which are given as examples of colored foreign matter, tend to be lighter than the damaged grains and colored grains, and therefore tend to arrive at the injection position Pj later than the damaged grains and colored grains, as shown in the upper part of FIG. 6. In view of this, the colored foreign matter timing Tk at which the injection unit 3 injects air onto the colored foreign matter is set later than the rice grain timing Tr at which the injection unit 3 injects air onto the damaged grains and colored grains. More specifically, the colored foreign matter timing Tk is set later than the end timing T1 at which the injection of air onto the damaged grains and colored grains ends. By setting the injection timing for the colored foreign matter to such a colored foreign matter timing Tk by the injection control unit 6, the colored foreign matter that tends to arrive at the injection position Pj later than the damaged grains and colored grains can be more reliably blown away, and therefore the colored foreign matter can be more reliably removed.

[0043] As shown in the middle and bottom of Fig. 6, the timing Tr for rice grains in this embodiment is set to a timing delayed by a delay time D1 from the detection completion timing Te at which the detection process by the detection unit 5 is completed (i.e., the timing at which the process at step SA5 or step SA6 shown in Fig. 4 is completed), and the timing Tk for colored foreign matter in this embodiment is set to a timing delayed by a delay time D2 longer than the delay time D1 from the detection completion timing Te. This makes it easy to manage the timing Tr for rice grains and the timing Tk for colored foreign matter, and makes it possible to reliably and easily delay the timing Tk for colored foreign matter with respect to the timing Tr for rice grains.

[0044] Fig. 7 is a diagram for explaining modified examples of the injection time by the injection unit 3. The upper part of Fig. 7 shows an example of the relationship between time (horizontal axis) and the positions (vertical axis) of colored foreign matter, colored foreign matter that reaches the injection position Pj with a delay, and damaged particles and colored particles, the middle part of Fig. 7 shows a timing chart of the detection process by the detection unit 5, and the lower part of Fig. 7 shows a timing chart of the injection by the injection unit 3.

[0045] In the example shown in FIG. 6, the injection time by the injection unit 3 is set to a uniform time J regardless of whether the injection target is a colored foreign object or a damaged grain and a colored grain, but as in the example shown in FIG. 7, the injection time J2 for colored foreign objects may be set longer than the injection time J1 for rice grains for damaged grains and colored grains. That is, when the judgment unit 52 judges that the object to be excluded Qr is a colored foreign object, the injection control unit 6 may set the injection time for the object to be excluded Qr to the injection time J2 for colored foreign objects longer than the injection time J1 for rice grains. This makes it possible to more reliably blow away the colored foreign object even if an error occurs in the speed at which the colored foreign object flows down the chute 1 and the colored foreign object reaches the injection position Pj with a further delay as shown by the thick dashed line in the upper part of FIG. 7, and therefore makes it possible to more reliably eliminate the colored foreign object.

[0046] (Embodiment 2) 8 is a block diagram showing a part of the configuration of a control system of the optical sorting machine A in embodiment 2. Next, the configuration of the optical sorting machine A in embodiment 2 of the present invention will be described, focusing on the differences from embodiment 1 above.

[0047] Incidentally, when the flow rate of the objects Q is relatively high, the objects Q come into contact with each other relatively frequently, and so the colored foreign matter flowing down the chute 1 may be swept away by the following rice grains, including damaged grains and colored grains, and may reach the injection position Pj almost simultaneously with the damaged grains and colored grains. Therefore, when the flow rate of the objects Q is relatively high, it is expected that the colored foreign matter will also be removed when the damaged grains and colored grains are blown away and removed at the rice grain timing Tr.

[0048] On the other hand, when the flow rate of the objects Q is relatively low, the objects Q have relatively few opportunities to come into contact with each other, so that the colored foreign matter flowing down the chute 1 is unlikely to be swept away by the following damaged grains and rice grains, including colored grains, and therefore the colored foreign matter is likely to reach the injection position Pj later than the damaged grains and colored grains. Therefore, when the flow rate of the objects Q is relatively low, more colored foreign matter tends to be removed by injecting air at the colored foreign matter timing Tk, which is later than the rice grain timing Tr, compared to when the flow rate of the objects Q is relatively high as described above. In other words, when the flow rate of the objects Q is relatively low, it can be said that the colored foreign matter can be efficiently removed by injecting air at the colored foreign matter timing Tk against the colored foreign matter.

[0049] Therefore, in the second embodiment, the control device 4B further includes a flow rate determination unit 7 that determines whether the flow rate of the object Q flowing down from the chute 1 (hereinafter simply referred to as the "flow rate of the object Q") is equal to or less than a predetermined threshold value, as shown in Fig. 8, and the injection control unit 6 sets the injection timing for the object Qr to be excluded to the colored foreign matter timing Tk when the flow rate of the object Q is equal to or less than the predetermined threshold value and when the determination unit 52 determines that the object Qr to be excluded is a colored foreign matter. In this way, by setting the injection timing for the colored foreign matter to the colored foreign matter timing Tk when the flow rate of the object Q is relatively low, the colored foreign matter can be efficiently eliminated.

[0050] Fig. 9 is a flowchart showing an example of a sorting process by the optical sorting machine A in embodiment 2. Next, the procedure of the sorting process by the optical sorting machine A in embodiment 2 will be described with reference to the flowchart in Fig. 9. Step SB1 and step SB4 to step SB11 shown in Fig. 9 are similar to step SA1 and step SA3 to step SA10 shown in Fig. 4, and therefore description thereof will be omitted.

[0051] In step SB2, the detection unit 5 and the flow rate determination unit 7 acquire the image P from the imaging unit 2. Then, in step SB3, the flow rate determination unit 7 acquires the flow rate of the object Q based on the image P captured by the imaging unit 2, and determines whether the flow rate is equal to or lower than a threshold value. The threshold value is, for example, stored in advance in the control device 4B. The flow rate determination unit 7 acquires the flow rate of the object Q, for example, by counting the number of pixels in a pixel area corresponding to each object Q appearing in the image P. The flow rate of the object Q depends on, for example, the processing capacity (amount of objects processed per unit time) of a device arranged as a pre-process of the optical sorting machine A.

[0052] If it is determined in step SB3 that the flow rate of the object Q is equal to or less than the threshold value, the process proceeds to step SB4, where the same process as in the above-described embodiment 1 is executed. On the other hand, if it is determined that the flow rate of the object Q exceeds the threshold value, the process proceeds to step SB11, where another sorting process is executed.

[0053] Here, a specific example in which the flow rate of the object Q is relatively low (below the threshold value) will be described. Fig. 10 is a graph showing an example of the change in the flow rate of the object Q over time. The thick solid line in Fig. 10 shows an example of the change in the flow rate of the object Q over time when a device with a relatively high processing capacity is placed upstream of the optical sorting machine A, the thick dashed line in Fig. 10 shows an example of the change in the flow rate of the object Q over time when a device with a standard processing capacity is placed upstream of the optical sorting machine A, and the thick dashed dotted line in Fig. 10 shows an example of the change in the flow rate of the object Q over time when a device with a relatively low processing capacity is placed upstream of the optical sorting machine A.

[0054] In each example shown in FIG. 10, the flow rate of the object Q gradually increases after the object Q starts flowing through the optical sorting machine A, and gradually decreases toward the end of the flow of the object Q. In the example shown by the thick solid line in FIG. 10, when the determination unit 52 determines that the object Qr to be excluded is a colored foreign matter during the period from the start of the flow of the object Q to the time when the flow rate of the object Q does not exceed the threshold value (the period shown by reference symbol F1 in FIG. 10) and during the period from when the flow rate of the object Q becomes equal to or lower than the threshold value to the end of the flow (the period shown by reference symbol F2 in FIG. 10), the injection control unit 6 sets the injection timing for the object Qr to the colored foreign matter timing Tk. On the other hand, in the example shown by the thick dashed line in FIG. 10, since the flow rate of the object Q is always equal to or lower than the threshold value from the start of the flow of the object Q to the end of the flow, when the determination unit 52 determines that the object Qr to be excluded is a colored foreign matter, the injection control unit 6 sets the injection timing for the object Qr to the colored foreign matter timing Tk.

[0055] It should be noted that the flow rate determining unit 7 may obtain the flow rate of the object Q using other detection means, instead of obtaining the flow rate of the object Q based on the image P as described above.

[0056] The above embodiments are illustrative in every respect and are not intended to be limiting. Therefore, the technical scope of the present invention is not interpreted solely by the above embodiments and examples, but is defined by the claims. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention. [Explanation of symbols]

[0057] A Optical sorting machine 1 Shot 2. Imaging unit 3 Injection part 5. Detection section 50 Color judgment section 51 Measuring part 52 Judgment section 6 Injection control section C1,C2 Contours J1 Injection time for rice grains J2 Injection time for colored foreign matter LS1,LS2 Longest line segment P Image Q Object Qr Exclusion Object S1, S2 size Tr Rice Timing Tk Colored foreign body timing α Colored part

Claims

1. An optical sorting machine for sorting granular objects, comprising: A chute for allowing the object to flow down; an imaging unit that images the object flowing down from the chute; a detection unit that detects a removal target to be removed from the object based on an image of the object captured by the imaging unit; an ejection unit that ejects air at a predetermined ejection timing for a predetermined ejection time toward the object to be removed so as to blow the object away; An injection control unit that controls the injection unit, The detection unit is a color determination unit that determines whether or not each of the objects is a rejection object that includes a colored portion based on the image; a measurement unit that measures a size of the object to be excluded that is determined to include the colored portion by the color determination unit and a size of the colored portion; a determination unit which, when a determination condition is satisfied that the size of the object to be excluded measured by the measurement unit is equal to the size of the colored portion measured by the measurement unit and that the size of the object to be excluded is smaller than the size of a rice grain, determines that the object to be excluded is a colored foreign matter, and, when the determination condition is not satisfied, determines that the object to be excluded is a damaged grain or a colored grain; The injection control unit is An optical sorting machine in which, when the judgment unit judges that the object to be excluded is a colored foreign matter, the injection timing for the object to be excluded is set to a timing for colored foreign matter that is slower than the timing for rice grains for damaged grains and colored grains.

2. 2. The optical sorting machine according to claim 1, The injection control unit of this optical sorting machine sets the injection timing for the object to be excluded to the timing for colored foreign matter when the flow rate of the object flowing down from the chute is below a predetermined threshold value and when the judgment unit judges that the object to be excluded is a colored foreign matter.

3. 2. The optical sorting machine according to claim 1, The measurement unit includes: An optical sorting machine that measures the length of the longest line segment that can be drawn within the outline of the object to be excluded on the image as the size of the object to be excluded, and measures the length of the longest line segment that can be drawn within the outline of the colored portion as the size of the colored portion.

4. 2. The optical sorting machine according to claim 1, The injection control unit is An optical sorting machine in which, when the judgment unit judges that the object to be excluded is a colored foreign matter, the spray time for the object to be excluded is set to a spray time for colored foreign matter that is longer than the spray time for rice grains for damaged grains and colored grains.

Images