Optical sorting machine

Abstract

An optical sorter including: an inspection part that is configured to perform optical inspection on granular objects transferred by transfer means; a judgment part that is configured to judge whether each granular object is a good article or a defective article based on the optical inspection performed by the inspection part; an ejector controller that includes multiple ejector nozzles and is configured to sort out the granular objects into the defective article and the good article by ejecting compressed air to the defective article from the ejector nozzles; and a sorting strength setting part that is capable of setting a sorting strength in the ejector controller, wherein the sorting strength is constituted of multiple sorting strength levels, and the sorting strength setting part is capable of presetting, for each of the sorting strength levels, multiple kinds of operation setting parameters that control an operation of the ejector nozzles.

Description

[Technical Field]

[0001] The present invention relates to an optical sorter which enables a user to easily perform an operation setting of an ejector nozzle of the optical sorter.[Background Art]

[0002] Heretofore, in order to remove a grain judged as a defective article, an optical sorter removes the grain judged as a defective article by ejecting compressed air to this grain from an ejector nozzle. Compressed air needs to hit on a defective article for a long period of time and in a wide range in order to remove the defective article reliably and obtain high-quality grains after the sorting. However, this causes a good article to be involved in compressed air and removed together and results in a reduction of yield. To deal with this, in order to reduce the number of good articles getting involved in compressed air as described above and achieve a high yield, an optical sorter is set in such a way that compressed air hits on a defective article for a short period of time and in a narrow range (see Patent Literature 1, for example). Patent Literature 2 discloses a color sorting machine in which decreases in yield resulting from the erroneous inclusion of good granules can be prevented by using different selection algorithms and operation ejector nozzle operations resulting therefrom in a first sorting part and a second sorting part.

[0003] Patent Literature 3 discloses a process and device for detecting and discarding objects, in particular glass or plastic bottles, based on determination of wear from usage, such as scratches.[Citation List][Patent Literature]

[0004] [Patent Literature 1] Japanese Patent No. 4206522 [Patent Literature 2] International (PCT) Application Publication No. WO-A-2011 / 158656 [Patent Literature 3] European Application Publication No. EP-A-1 900 446 [Summary of Invention][Technical Problem]

[0005] In the existing optical sorter described above, individual items such as a delay period and an ejection period can be set for the ejector nozzle operation setting; however, a specialized maintenance engineer needs to take time to make settings when adjusting a yield level between high and low. For example, depending on whether to set a high yield or not and whether to set normal sorting or high-quality sorting, a specialized maintenance engineer needs to take time to perform the ejector nozzle operation setting through trial and error. Accordingly, it is sometimes difficult for an ordinary user to make settings easily.

[0006] Against this background, a problem to be solved by the present invention is to provide an optical sorter which enables a user to easily perform an operation setting of an ejector nozzle of the optical sorter.[Solution to Problem]

[0007] (1) An optical sorter including: an inspection part that is configured to perform optical inspection on granular objects transferred by transfer means; a judgment part that is configured to judge whether each granular object is a good article or a defective article based on the optical inspection performed by the inspection part; an ejector controller that includes multiple ejector nozzles and is configured to sort out the granular objects into the defective article and the good article by ejecting compressed air to the defective article from the ejector nozzles; and a sorting strength setting part that is capable of setting a sorting strength in the ejector controller, wherein the sorting strength is constituted of multiple sorting strength levels, and the sorting strength setting part is capable of presetting, for each of the sorting strength levels, multiple kinds of operation setting parameters that control an operation of the ejector nozzles. (2) The optical sorter according to claim 1, wherein the ejector controller is capable of varying ejection ranges of compressed air by the multiple ejector nozzles according to the multiple sorting strength levels. (3) The optical sorter according to claim 1 or 2, wherein the ejector controller includes fault area identification means that is capable of identifying a fault area in the defective article, and the fault area identification means is capable of performing, on area fault pixels arranged continuously in a lateral direction, thinning processing to leave a center line portion of the area fault pixels as fault pixels. (4) The optical sorter according to claim 3, wherein the multiple kinds of operation setting parameters at least include an ejection period by the ejector nozzles and an overlap value that indicates a width of an overlap area which straddles the ejection ranges of adjacent ones of the ejector nozzles while sandwiching a boundary line between the adjacent ejector nozzles, and the ejector controller causes both of the adjacent ejector nozzles to perform an ejection operation if at least a part of the fault area falls within the overlap area. (5) The optical sorter according to any one of claims 1 to 4, wherein the sorting strength setting part is connected to setting input means, which enables a user of the optical sorter to select any of the sorting strength levels, and is capable of adjusting a yield according to the sorting strength level thus selected. (6) The optical sorter according to claim 5, the setting input means enables a presetting operation of the operation setting parameters for each of the sorting strength levels. (7) The optical sorter according to claim 6, wherein in response to the presetting operation of the operation setting parameters at one of the sorting strength levels, the setting input means enables setting of the operation setting parameters at other sorting strength levels without the presetting operation thereof. [Advantageous Effects of Invention]

[0008] According to the invention as specified in the above item (1), it is possible to remove the granular object being the defective article using the multiple ejector nozzles that are controlled according to the sorting strength level set by the sorting strength setting part. Further, the sorting strength levels described above are configured in such a way that the multiple kinds of operation setting parameters that control the operation of the ejector nozzles can be preset for each of the multiple sorting strength levels. Accordingly, a user himself / herself can perform the setting of the optical sorter very easily according to the yield and quality requested by the user without having to take time to perform the operation setting of the ejector nozzles as in the past.

[0009] According to the invention as specified in the above item (2), it is possible to adjust the ejection ranges of compressed air by the multiple ejector nozzles so that they vary according to the multiple sorting strength levels. This enables a defective article to be sorted and removed appropriately according to the yield and quality requested by the user.

[0010] According to the invention as specified in the above item (3), it is possible to identify the fault area in the defective article, and perform, on the area fault pixels arranged continuously in the lateral direction, thinning processing to leave the center line portion of the area fault pixels as fault pixels. This processing makes it possible to narrow down the ejection ranges of compressed air by the multiple ejector nozzles and possible to improve the yield.

[0011] According to the invention as specified in the above item (4), the settable operation setting parameters for the ejector nozzles at least include the ejection period by the ejector nozzles and the overlap value that indicates the width of the overlap area which straddles the ejection ranges of adjacent ones of the ejector nozzles while sandwiching the boundary line between the adjacent ejector nozzles. The optical sorter is configured in such a way that both of the two adjacent ejector nozzles perform the ejection operation if at least a part of the fault area in the granular object falls within the overlap area. This makes it possible to adjust the ejection range of compressed air by adjusting the overlap value and possible to sort and remove the defective article according to the yield and quality requested by the user.

[0012] According to the invention as specified in the above item (5), the user of the optical sorter can select the sorting strength level using the setting input means. For example, through a console screen as shown in Figure 4, the user can select the sorting strength level very easily according to the yield and quality requested by the user.

[0013] According to the invention as specified in the above item (6), through a console screen as shown in Figure 10 for example, an operator such as a maintenance engineer can preset the operation setting parameters easily for each of the sorting strength levels.

[0014] According to the invention as specified in the above item (7), the optical sorter is configured in such a way that, by presetting the operation setting parameters at one of the sorting strength levels, the operation setting parameters at other sorting strength levels are set automatically based on a predetermined setting rule. This configuration makes it possible to save the time and effort required to preset the operation setting parameters individually for all the sorting strength levels.[Brief Description of Drawings]

[0015] [Figure 1] Figure 1 shows a schematic longitudinal sectional view illustrating an internal structure of an optical sorter in an embodiment of the present invention. [Figure 2] Figure 2 shows a block diagram of control processing means of an optical sorter in an embodiment of the present invention. [Figure 3] Figure 3 shows a diagram illustrating an outline of a sorting strength level in an embodiment of the present invention. [Figure 4] Figure 4 shows a diagram illustrating how a sorting strength level adjustment screen is displayed on a liquid crystal display in an embodiment of the present invention. [Figure 5] Figure 5 shows a diagram illustrating image processing on grains performed at the time of determining an ejection area in an embodiment of the present invention. [Figure 6] Figure 6 shows a conceptual diagram illustrating various operation setting parameters and ejection areas in primary sorting using the optical sorter, in an embodiment of the present invention (sorting strength levels 5 to 3). [Figure 7] Figure 7 shows a conceptual diagram illustrating various operation setting parameters and ejection areas in the primary sorting using the optical sorter, in an embodiment of the present invention (sorting strength levels 2 and 1). [Figure 8] Figure 8 shows a conceptual diagram illustrating various operation setting parameters and ejection areas in secondary sorting and tertiary sorting using the optical sorter, in an embodiment of the present invention (sorting strength levels 5 to 3). [Figure 9] Figure 9 shows a conceptual diagram illustrating various operation setting parameters and ejection areas in the secondary sorting and tertiary sorting using the optical sorter, in an embodiment of the present invention (sorting strength levels 2 and 1). [Figure 10] Figure 10 shows a diagram illustrating how a setting screen for maintenance engineers is displayed on a liquid crystal display in an embodiment of the present invention. [Description of Embodiments]

[0016] An embodiment of an optical sorter of the present invention will be described below based on the drawings. Figure 1 shows a schematic longitudinal sectional view illustrating an internal structure of an optical sorter 1 in this embodiment. Figure 2 shows a block diagram illustrating a configuration of control processing means of the optical sorter 1.(Configuration of Optical Sorter)

[0017] As shown in Figure 1, the optical sorter 1 includes, in a machine frame 2: a chute 4 that slopes at an angle of approximately 60 degrees with respect to the horizontal position and is configured to transfer grains 100 as transfer means of the grains 100; a reservoir tank 5 that is designed to reserve the grains 100; a vibrating feeder 6 that is configured to convey the grains 100 from the reservoir tank 5 to the chute 4; optical detectors 7a and 7b that are provided so as to vertically sandwich dropping trajectories of the grains 100 dropping from the lower end of the chute 4; an ejector 8 that is provided below the optical detectors 7a and 7b; a good article collecting gutter 9 that is located below the ejector 8 at a position on the same line of inclination as the chute 4 and designed to receive the grains 100 which drop along the dropping trajectories without receiving an air blast from ejector nozzles 80; a defective article collecting gutter 10 that is arranged side by side with the good article collecting gutter 9 and designed to collect defective grains having received an air blast from the ejector nozzles 80; and an auxiliary defective article collecting gutter 11 that is designed to collect defective grains having failed to receive an air blast from the ejector nozzles 80, hit a peripheral member, and bounced back.

[0018] The chute 4 is formed to have the shape of a flat plate with no groove portion so as to allow the grains 100 to slide on a band-shaped path with a large width. In order to prevent the grains 100 from overflowing from the chute 4 and prevent the grains 100 from floating from a bottom surface of the chute 4 during sliding on the chute 4, a chute cover 4a is provided with a predetermined interval from the bottom surface.

[0019] The vibrating feeder 6 has a feeder trough 6a supported on a support part 6b, and is configured to be capable of feeding the grains 100 to the chute 4 by actuating a vibrating member such as an electromagnetic driven coil 6c. Note that, the above chute 4 may have a shape with a groove portion, and cross-sectional shapes such as a U-shaped cross section, a V-shaped cross section, and a concave cross section may be employed as appropriate as the cross-sectional shape of the groove portion.

[0020] The optical detectors 7a and 7b serving as inspection parts for performing optical inspection are respectively enclosed by box bodies 12a and 12b. The box body 12a, located ahead of the dropping trajectories of the grains 100, is furnished with: a CCD camera 13a for visible light; an NIR camera 14 for near-infrared light; visible light sources 15a and 15b constituted of fluorescent lamps and the like; a near-infrared light source 16a constituted of a halogen lamp and the like; and a background 17a for facing the optical detector 7b.

[0021] The box body 12b, located behind the dropping trajectories of the grains 100, is furnished with: a CCD camera 13b for visible light; visible light sources 15c and 15d constituted of fluorescent lamps and the like; a near-infrared light source 16b constituted of a halogen lamp and the like; and backgrounds 17b and 17c for facing the optical detector 7a. Window members 18a and 18b constituted of transparent glass are fitted to the box bodies 12a and 12b on sides thereof close to the dropping trajectories of the grains 100.

[0022] The ejector 8 of the optical sorter 1 of this embodiment is provided with the 48 ejector nozzles 80 arranged in a line at equal intervals in the same direction as the width direction of the chute 4. Each ejector nozzle 80 includes an ejector solenoid valve 81 that is configured to turn on / off an ejection of compressed air. Here, the number of ejector nozzles 80 can be changed as appropriate according to factors such as the width dimensions of the chute 4. The ejector 8 of this embodiment is capable of storing compressed air therein, and is configured to feed air from an air compressor (not illustrated) via an air supply pipe 22. Note that, one or more sub-tanks (not illustrated) may be provided between the ejector 8 and the air compressor to store air temporarily. This configuration eliminates the risk of air shortage even when the amount of air ejected from the ejector nozzles 80 is large.

[0023] A front door 24 that is vertically pivotable by an air cylinder 23 is provided on a front sloping wall of the machine frame 2. This can facilitate maintenance work such as cleaning. Below the front door 24, a liquid crystal display 25 that functions as setting input means in which a console panel constituted of a touch panel and a monitor are combined and a power switch (not illustrated) are provided. Such a configuration in which the liquid crystal display 25 and the power switch are arranged at an operator's eye level can facilitate machine operation.

[0024] As shown in Figure 1, a defective article receptable 27, a good article receptable 28, and an auxiliary defective article receptable 29 are provided as receptables for the sorted grains 100. In addition, a sample fetch part 30 is provided above the defective article receptable 27.

[0025] The configuration of the control processing means of the optical sorter 1 will be described with reference to Figure 2. The CCD cameras 13a and 13b for visible light and the NIR camera 14 for near-infrared light are electrically connected to a signal processing part 31 to binarize acquired images. The signal processing part 31 is connected to a memory part 32 that stores images to perform necessary processing thereon. The liquid crystal display 25 is electrically connected to the memory part 32.

[0026] The signal processing part 31 at least includes: an image data acquisition part 33 that temporarily stores image data; a threshold data storage memory 34 that stores threshold data for determining whether the acquired image data is good or defective; a binarization calculation mechanism 35 for binarizing the acquired image data; a good / defective judgment part 36 that functions as a judgment part configured to judge whether a target article is good or defective; and an ejector controller 37 that is configured to control the operation of the ejector 8.

[0027] The CCD cameras 13a and 13b for visible light and the NIR camera 14 for near-infrared light are each connected, via an I / V converter (not illustrated) that is configured to convert the detected light intensity value into a voltage value, to an amplifier that is configured to amplify the voltage value. Then, based on the amplified voltage values (detection signals), the good / defective judgment part 36 compares them with the threshold values stored in the threshold data storage memory 34 to judge whether a target article is good or defective.

[0028] The memory part 32 at least includes: an image data storage memory 38 that stores data from the image data acquisition part 33 as necessary; a threshold data calculation mechanism 39 that is configured to calculate a threshold value for judging whether a grain is good or defective based on the image data stored in the image data storage memory 38; a sorting strength setting part 40 that is configured to perform an operation setting of the ejector 8; a manipulation signal reception mechanism 41 for receiving a signal generated by a touch operation on the liquid crystal display 25 and outputting the processed image data to the liquid crystal display 25.

[0029] The good / defective judgment part 36 in the signal processing part 31 is electrically connected to the ejector controller 37, and the ejector controller 37 controls an ejector drive circuit 42 so as to remove a defective grain 100 based on the operating conditions of the ejector 8 set in the sorting strength setting part 40 of the memory part 32.

[0030] As shown in Figure 2, the above ejector drive circuit 42 is electrically connected to each of the ejector solenoid valves 81 that turn on / off an ejection of compressed air by the respective ejector nozzles 80. The optical sorter is configured in such a way that the ejector drive circuit 42 inputs a drive signal to each of the ejector solenoid valves 81 to open or close the corresponding ejector solenoid valve 81. As described previously, the ejector 8 of this embodiment includes the 48 ejector nozzles 80, and the ejector nozzles 80 respectively include the ejector solenoid valves 81. Note that, out of the 48 ejector solenoid valves 81, Figure 2 shows a first ejector solenoid valve 81a, a second ejector solenoid valve 81b, and a third ejector solenoid valve 81c which are adjacent to each other and can eject compressed air to the whole body of a single grain 100.(Configuration of Sorting Processing)

[0031] Sorting processing of the optical sorter 1 of this embodiment will be described below in detail.

[0032] The optical sorter 1 of this embodiment can previously set the sorting strength at the time of removing the grains 100 judged as a defective article by the ejector 8. In other words, as shown in Figure 3, the optical sorter can set the sorting strength in five levels, i.e. from Level 5 to Level 1. Level 1 has a high sorting strength and can reliably sort out defective articles, and therefore some good articles may be involved in compressed air ejected from the ejector nozzles 80 and removed together. Accordingly, Level 1 results in a low yield but can achieve high-quality grains 100. On the other hand, Level 5 has a low sorting strength, and therefore some defective articles may not be removed by the ejector 8. Accordingly, Level 5 results in a high yield but the quality of the resultant grains 100 is low. Note that, how the ejector 8 operates at each of the sorting strengths will be described in detail later.

[0033] Figure 4 shows an example of a display mode on the liquid crystal display 25. The optical sorter 1 is configured in such a way that a sorting strength level adjustment screen as shown in the drawing is displayed once a user using the optical sorter 1 touches an ejector setting icon 253 with his / her finger. Then, by touching a level-up icon 251 and a level-down icon 252, a desired sorting strength level of the ejector 8 can be selected easily. Note that, the sorting strength level may alternatively be selected by touching a round-shaped setting level icon 255 shown in the drawing and flicking it to a desired level position.

[0034] Based on Figure 5, a description will be given of how a grain 100 being a defective article is identified when the ejector 8 removes the defective article. In step 1, the good / defective judgment part 36 acquires an object image of the grain 100. Next, in step 2, a defective area in the grain 100 is identified by a calibration dose based on a light intensity detection value obtained from the object image. Then, in step 3, a fault area that meets a defective size to be judged as defective is identified based on a predetermined threshold value set in advance. Next, in step 4, fault pixels of the fault area arranged continuously in the lateral direction are subjected to thinning processing to leave only the center line thereof as the fault area. As will be described in detail later, this thinning processing can bring about an effect of improving the yield. Then, in step 5, based on the fault area thus identified, the ejection ranges of compressed air by the ejector nozzles 80 according to the sorting strength level set in advance (Levels 5 to 1) are determined. Note that, as shown in Figure 5, the thinning processing in step 4 is not essential, and the ejection range setting in step 5 may be performed without the thinning processing according to need.

[0035] Next, a description will be given of operation setting parameters at each of the sorting strength levels (Levels 5 to 1) in this embodiment.

[0036] Figures 6 and 7 show conceptual diagrams illustrating various operation setting parameters that are preset for each of the sorting strength levels (Levels 5 to 1), compressed air ejection areas for the defective grain 100, and the like. Note that, Figures 6 and 7 show an embodiment of primary sorting performed by the optical sorter 1 equipped with the chute 4 in the form of a flat plate. Figures 8 and 9 show an embodiment of secondary sorting and tertiary sorting performed by the optical sorter 1 equipped with the U-shaped chute 4. The conceptual diagrams of Figures 6 to 9 show, out of the 48 ejector nozzles 80 described above, a first ejector nozzle 80a, a second ejector nozzle 80b, and a third ejector nozzle 80c which are adjacent to each other and can eject compressed air to the whole body of a single grain 100.

[0037] In this embodiment, as shown in Figures 6 to 9, the following operation items are preset as the operation setting parameters for each of the sorting strength levels (Levels 5 to 1): (1) a compressed air "ejection period"; (2) an "overlap value" that enables the adjacent ejector nozzles 80 to be actuated when a fault area exists in an overlap area which straddles the ejection ranges of both ejector nozzles 80 while sandwiching the boundary between these nozzles therein; and (3) an ON / OFF setting of the "thinning processing" that leaves, as the fault area, only the center line of the fault pixels of the fault area of the defective article arranged continuously in the lateral direction.

[0038] Subsequently, a description will be given of how the ejector 8 operates on the defective grain 100 at these operation setting parameters. The "Level 5" setting shown in Figure 6 is the setting that results in a high yield, and is preset to "10" for the ejection period, "0" for the overlap value, and "ON" for the thinning processing. Note that, the ejection period "10" is not a value in units of time but an arbitrary defined value, and is actually a period in which compressed air hits on a dropping grain 100 in a range illustrated by a two-headed arrow in the drawing. Needless to say, this value may be set in units of time.

[0039] In the "Level 5" setting shown in Figure 6, the overlap value is set to "0". In this case, only the second ejector nozzle 80b which can eject compressed air to an identified fault area operates. In addition, in the "Level 5" setting, since the thinning processing is set to "ON", a linear fault area as shown in the drawing is identified, and this area is smaller than the actual fault area.

[0040] Next, the "Level 4" setting shown in Figure 6 has a higher sorting strength and results in a slightly lower yield, but can achieve the grains 100 of slightly higher quality than the "Level 5" setting described above. The ejection period is preset to "15" which is about 1.5 times as long as that of "Level 5", the overlap value is preset to "4", and the thinning processing is preset to "ON". Note that, the overlap value "4" does not have a specific unit, but is an arbitrarily defined value. For example, the overlap value may be the number of pixels in the width direction of an image sensor, which is a value equivalent to the length in the width direction of the overlap area shown in the drawing. Needless to say, this overlap value may be set to a value in units of distance (dimensions).

[0041] In the "Level 4" setting shown in Figure 6, the overlap value is set to "4". Accordingly, as shown in the drawing, overlap areas which straddle the ejection ranges of the first ejector nozzle 80a and the second ejector nozzle 80b adjacent to each other and the ejection ranges of the second ejector nozzle 80b and the third ejector nozzle 80c adjacent to each other while sandwiching the boundary line between the first and second ejector nozzles 80a and 80b and the boundary line between the second and third ejector nozzles 80b and 80c, respectively, are set. In the embodiment shown in the drawing, only the second ejector nozzle 80b operates since the fault area subjected to the thinning processing falls within the ejection range of the second ejector nozzle 80b without entering the overlap areas.

[0042] Next, the "Level 3" setting shown in Figure 6 has a higher sorting strength than the "Level 4" setting described above. The ejection period is preset to "20" which is twice as long as that of "Level 5", the overlap value is preset to "8" which is twice as large as that of "Level 4", and the thinning processing is preset to "ON". In the "Level 3" setting, the overlap value is set to "8" and the width of each overlap area is twice as large as that of "Level 4". However, in the embodiment shown in the drawing, only the second ejector nozzle 80b operates since the fault area subjected to the thinning processing falls within the ejection range of the second ejector nozzle 80b without entering the overlap areas.

[0043] Next, the "Level 2" setting shown in Figure 7 has a higher sorting strength than the "Level 3" setting described above. The ejection period is preset to "25" which is 2.5 times as long as that of "Level 5", the overlap value is preset to "14" which is approximately twice as large as that of "Level 3", and the thinning processing is preset to "OFF".

[0044] In the "Level 2" setting shown in Figure 7, the overlap value is set to "14" and the width of each overlap area is approximately twice as large as that of "Level 3" as shown in the drawing. In the embodiment shown in the drawing, an upper right portion of the fault area (thinning processing: OFF) falls within the overlap area set between the second ejector nozzle 80b and the third ejector nozzle 80c. This causes the third ejector nozzle 80c to operate in addition to the second ejector nozzle 80b to eject compressed air to the grain 100 in the range of the ejection areas shown in the drawing.

[0045] Next, the "Level 1" setting shown in Figure 7 has a higher sorting strength than the "Level 2" setting described above. The ejection period is preset to "30" which is three times as long as that of "Level 5", the overlap value is preset to "20" which is approximately 1.5 times as large as that of "Level 4", and the thinning processing is preset to "OFF".

[0046] In the "Level 1" setting shown in Figure 7, the overlap value is set to "20" and the width of each overlap area is approximately 1.5 times as large as that of "Level 2" as shown in the drawing. In the embodiment shown in the drawing, an upper right portion and a lower left portion of the fault area (thinning processing: OFF) fall within the overlap area set so as to straddle the boundary line between the second ejector nozzle 80b and the third ejector nozzle 80c and the overlap area set between the second ejector nozzle 80b and the first ejector nozzle 80a, respectively. This causes the third ejector nozzle 80c and the first ejector nozzle 80a to operate in addition to the second ejector nozzle 80b to eject compressed air to the grain 100 in the range of the ejection areas shown in the drawing.

[0047] Accordingly, in the "Level 1" setting, the ejection areas of the ejector nozzles 80 are wider than the outer shape of the target grain 100. However, since the grains 100 flow down continuously in a band shape while being close to each other, some good articles near the defective article are involved in compressed air ejected from the ejector nozzles 80 and removed together. Hence, Level 1 results in a low yield, but can achieve high-quality grains 100 because defective articles can be removed reliably.

[0048] Subsequently, a description will be given of how the ejector 8 operates on the defective grain 100 at the operation setting parameters in the secondary sorting and tertiary sorting, which are shown in Figures 8 and 9. Here, the secondary sorting and tertiary sorting refer to a sorting process of feeding the grains 100, obtained after the primary sorting performed by the optical sorter 1, to the optical sorter 1 again to perform secondary and tertiary sorting processes repeatedly. In addition, the secondary sorting and tertiary sorting described above use the chute 4 provided with multiple U-shaped grooves each having a width sufficient for one grain 100 to flow down. As shown by the schematic diagrams of Figures 8 and 9, the compressed air ejection area of one ejector nozzle 80 is about the same width as the width of each grain 100.

[0049] The "Level 5" setting shown in Figure 8 is the setting that results in a high yield, and is preset to "10" for the ejection period, "0" for the overlap value, and "ON" for the thinning processing. In the "Level 5" setting, the overlap value is set to "0". In this case, only the second ejector nozzle 80b which can eject compressed air to an identified fault area operates. In addition, in the "Level 5" setting, since the thinning processing is set to "ON", a linear fault area as shown in the drawing is identified, and this area is smaller than the actual fault area.

[0050] Next, the "Level 4" setting shown in Figure 8 has a higher sorting strength and results in a slightly lower yield, but can achieve the grains 100 of slightly higher quality than the "Level 5" setting described above. The ejection period is preset to "15" which is about 1.5 times as long as that of "Level 5", the overlap value is preset to "0", and the thinning processing is preset to "ON" .

[0051] Next, the "Level 3" setting shown in Figure 8 has a higher sorting strength and results in a lower yield, but can achieve the grains 100 of slightly higher quality than the "Level 4" setting described above. The ejection period is preset to "20" which is twice as long as that of "Level 5", the overlap value is preset to "0", and the thinning processing is preset to "ON".

[0052] Next, the "Level 2" setting shown in Figure 9 has a higher sorting strength and results in a further lower yield, but can achieve the grains 100 of higher quality than the "Level 3" setting described above. The ejection period is preset to "25" which is 2.5 times as long as that of "Level 5", the overlap value is preset to "8", and the thinning processing is preset to "OFF".

[0053] In the "Level 2" setting shown in Figure 9, the overlap value is set to "8". Accordingly, as shown in the drawing, overlap areas are set between the first ejector nozzle 80a and the second ejector nozzle 80b adjacent to each other and between the second ejector nozzle 80b and the third ejector nozzle 80c adjacent to each other, respectively. In the embodiment shown in the drawing, only the second ejector nozzle 80b operates since the fault area (thinning processing: OFF) falls within the ejection range of the second ejector nozzle 80b without entering the overlap areas.

[0054] Next, the "Level 1" setting shown in Figure 9 has a higher sorting strength than the "Level 2" setting described above. The ejection period is preset to "30" which is three times as long as that of "Level 5", the overlap value is preset to "16" which is twice as large as that of "Level 2", and the thinning processing is preset to "OFF".

[0055] In the "Level 1" setting shown in Figure 9, the overlap value is set to "16" and the width of each overlap area is twice as large as that of "Level 2" as shown in the drawing. In the embodiment shown in the drawing, a left portion of the fault area (thinning processing: OFF) falls within the overlap area set so as to straddle the boundary line between the second ejector nozzle 80b and the first ejector nozzle 80a. This causes the first ejector nozzle 80a to operate in addition to the second ejector nozzle 80b to eject compressed air to the grain 100 in the range of the ejection areas shown in the drawing.

[0056] Accordingly, in the "Level 1" setting, the ejection areas of the ejector nozzles 80 are wider than the outer shape of the target grain 100. However, since the grains 100 flow down continuously in a band shape while being close to each other, some good articles near the defective article are sometimes involved in compressed air ejected from the ejector nozzles 80 and removed together. Hence, Level 1 results in a low yield, but can achieve high-quality grains 100 because defective articles can be removed reliably.

[0057] One example of the operation setting parameters at each of the sorting strength levels in this embodiment has been described above. Out of the 48 ejector nozzles 80, the ejector nozzles 80 located at their both end portions each have the adjacent ejector nozzle 80 only on one side. Accordingly, in the case of setting the overlap value, these ejector nozzles 80 operate with the overlap area set only on one side where the adjacent ejector nozzle 80 exists. In addition, the operation setting parameters of the "ejection period", "overlap", and "thinning processing" described above are preset by a maintenance engineer, and thus a user of the optical sorter 1 only needs to specify the sorting strength level, as described above, in a setting screen as shown in Figure 4. Accordingly, it is possible to greatly reduce the time and effort which has been required in the past for a maintenance engineer to frequently set the operation setting parameters and take time to perform the operation setting of the ejector 8 through trial and error.

[0058] Note that, Figure 10 shows an example of a setting screen for maintenance engineers, and by touching a detailed setting icon 254 at an upper right corner of the display screen, a maintenance engineer can move to a detailed setting screen (not illustrated) and set the operation setting parameters of the "ejection period", "overlap", and "thinning processing" at each of the sorting strength levels. In addition, once the maintenance engineer sets the operation setting parameters at one of Levels 5 to 1 when setting the operation setting parameters, the operation setting parameters at other sorting strength levels are set automatically according to the level.

[0059] According to this configuration, it is possible to save the time and effort required to enter the operation setting parameters for all the other sorting strength levels at the time of setting and changing the operation setting parameters.(Other Embodiments)

[0060] One embodiment of the optical sorter of the present invention has been described above. However, the present invention is not necessarily limited to the above embodiment, but also includes the following modification examples, for example.

[0061] For example, although the method of sorting the grains 100 has been described in the above embodiment, a sorting target is not necessarily limited to the grains 100. The optical sorter of the present invention may be applicable effectively to the case of sorting granular objects including resin pieces such as pellets and beads and fine articles such as pulses, medicines, ores, and whitebait.

[0062] Meanwhile, although the sorting strength level has been set in five levels from "Level 5" to "Level 1" in the above embodiment, the sorting strength level does not necessarily have to be set in five levels, but may be set in any number of levels.

[0063] Meanwhile, in the above embodiment, the three kinds of setting items "ejection period", "overlap", and "thinning processing" have been preset at each of the sorting strength levels. Since these setting items have a significant influence on yield and quality, it is possible to effectively adjust yield and quality by making these items presettable. However, the setting items are not necessarily limited to these items, but many other types of setting items may be made presettable.

[0064] Meanwhile, although the optical sorter of the above embodiment has been configured to be capable of level adjustment from low yield to high yield as shown in Figure 4, the level adjustment is not necessarily limited to such a configuration. For example, the operation setting parameters may be set for each of the sorting strength levels with emphasis on the quality of granular objects to be obtained so as to enable level adjustment from low quality to high quality. Then, in the level selection screen as shown in Figure 4, a user may select levels between low quality to high quality in addition to the level selection between low yield to high yield.

[0065] Meanwhile, the optical sorter may be further equipped with switching means for turning on / off the sorting strength level selection function as shown in Figure 4. Such a configuration makes it possible to turn off the selection function in response to a user's request and finely set each operation setting parameter individually.

[0066] The embodiment of the present invention and some modification examples thereof have been described above. However, the above embodiment of the present invention is intended to facilitate understanding of the present invention and is not intended to limit the present invention.[Reference Signs List]

[0067] 1OPTICAL SORTER 2MACHINE FRAME 4CHUTE 4aCHUTE COVER 5RESERVOIR TANK 6VIBRATING FEEDER 6aFEEDER TROUGH 6bSUPPORT PART 6cELECTROMAGNETIC DRIVEN COIL 7aOPTICAL DETECTOR 7bOPTICAL DETECTOR 8EJECTOR 9GOOD ARTICLE COLLECTING GUTTER 10DEFECTIVE ARTICLE COLLECTING GUTTER 11AUXILIARY DEFECTIVE ARTICLE COLLECTING GUTTER 12aBOX BODY 12bBOX BODY 13aCCD CAMERA 13bCCD CAMERA 14NIR CAMERA 15aVISIBLE LIGHT SOURCE 15bVISIBLE LIGHT SOURCE 15cVISIBLE LIGHT SOURCE 15dVISIBLE LIGHT SOURCE 16aNEAR-INFRARED LIGHT SOURCE 16bNEAR-INFRARED LIGHT SOURCE 17aBACKGROUND FOR FACING 17bBACKGROUND FOR FACING 17cBACKGROUND FOR FACING 18aWINDOW MEMBER 18bWINDOW MEMBER 22AIR SUPPLY PIPE 24FRONT DOOR 25LIQUID CRYSTAL DISPLAY 27DEFECTIVE ARTICLE RECEPTABLE 28GOOD ARTICLE RECEPTABLE 29AUXILIARY DEFECTIVE ARTICLE RECEPTABLE 30SAMPLE FETCH PART 31SIGNAL PROCESSING PART 32MEMORY PART 33IMAGE DATA ACQUISITION PART 34THRESHOLD DATA STORAGE MEMORY 35BINARIZATION CALCULATION MECHANISM 36GOOD / DEFECTIVE JUDGMENT PART 37EJECTOR CONTROLLER 38IMAGE DATA STORAGE MEMORY 39THRESHOLD DATA CALCULATION MECHANISM 40SORTING STRENGTH SETTING PART 41MANIPULATION SIGNAL RECEPTION MECHANISM 42EJECTOR DRIVE CIRCUIT 80EJECTOR NOZZLE 80aFIRST EJECTOR NOZZLE 80bSECOND EJECTOR NOZZLE 80cTHIRD EJECTOR NOZZLE 81EJECTOR SOLENOID VALVE 81aFIRST EJECTOR SOLENOID VALVE 81bSECOND EJECTOR SOLENOID VALVE 81cTHIRD EJECTOR SOLENOID VALVE 100GRAIN 251LEVEL-UP ICON 252LEVEL-DOWN ICON 253EJECTOR SETTING ICON 254DETAILED SETTING ICON 255SETTING LEVEL ICON

Claims

1. An optical sorter (1) comprising: an inspection part (7a, 7b) that is configured to perform optical inspection on granular objects transferred by transfer means; a judgment part (36) that is configured to judge whether each granular object is a good article or a defective article based on the optical inspection performed by the inspection part; and an ejector controller (37) that includes multiple ejector nozzles and is configured to sort out the granular objects into the defective article and the good article by ejecting compressed air to the defective article from the ejector nozzles; the optical sorter characterized by further comprising a sorting strength setting part (40) that is capable of setting a sorting strength in the ejector controller, wherein the sorting strength is constituted of multiple sorting strength levels, and the sorting strength setting part (40) is capable of presetting, for each of the sorting strength levels, multiple kinds of operation setting parameters that control an operation of the ejector nozzles.

2. The optical sorter (1) according to claim 1, wherein the ejector controller (37) is capable of varying ejection ranges of compressed air by the multiple ejector nozzles according to the multiple sorting strength levels.

3. The optical sorter (1) according to claim 1 or 2, wherein the ejector controller (37) includes fault area identification means that is capable of identifying a fault area in the defective article, and the fault area identification means is capable of performing, on area fault pixels arranged continuously in a lateral direction, thinning processing to leave a center line portion of the area fault pixels as fault pixels.

4. The optical sorter (1) according to claim 3, wherein the multiple kinds of operation setting parameters at least include an ejection period by the ejector nozzles and an overlap value that indicates a width of an overlap area which straddles the ejection ranges of adjacent ones of the ejector nozzles while sandwiching a boundary line between the adjacent ejector nozzles, and the ejector controller (37) causes both of the adjacent ejector nozzles to perform an ejection operation if at least a part of the fault area falls within the overlap area.

5. The optical sorter (1) according to any one of claims 1 to 4, wherein the sorting strength setting part (40) is connected to setting input means, which enables a user of the optical sorter to select any of the sorting strength levels, and is capable of adjusting a yield according to the sorting strength level thus selected.

6. The optical sorter (1) according to claim 5, wherein the setting input means enables a presetting operation of the operation setting parameters for each of the sorting strength levels.

7. The optical sorter (1) according to claim 6, wherein, in response to the presetting operation of the operation setting parameters at one of the sorting strength levels, the setting input means enables setting of the operation setting parameters at other sorting strength levels without the presetting operation thereof.

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