Optical sorting machine

Abstract

To increase types of defectives and / or foreign matters that can be discriminated based on a detection result of red light in an optical sorting machine.SOLUTION: An optical sorting machine comprises: a first red light source which is disposed on a first side with respect to a transfer path of a plurality of sorting objects; a second red light source which is disposed on a second side opposite to the first side; a first optical sensor which is disposed on the first side; a second optical sensor which is disposed on the second side; a determination unit which determines foreign matters and / or defectives based on signals acquired by the first optical sensor and second optical sensor; and a light source control unit which controls the first red light source and second red light source. The light source control unit controls the first red light source and second red light source such that the first red light source and second red light source are turned on in the first scanning period and the first red light source is turned on and the second red light source is not turned on in the second scanning period.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an optical sorter. [Background technology]

[0002] Conventionally, optical sorting machines are known in which a red light source that emits red light is provided on one side of a transport path for the objects to be sorted, and optical sensors are provided on both sides of the transport path (for example, see Patent Document 1 below). With this type of optical sorting machine, the optical sensor on one side detects the red light reflected by the objects to be sorted, and the optical sensor on the other side detects the red light that has passed through the objects to be sorted. The optical sorting machine described in Patent Document 1 determines whether the rice grains to be sorted are sardines or not based on the detection results of the red reflected light and transmitted light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2010-42326 Summary of the Invention [Problem to be solved by the invention]

[0004] However, although the optical sorting machine can distinguish between sappan and sappan based on the detection result of red light, the types of defective products that can be distinguished are limited. Therefore, it is required to increase the types of defective products and / or foreign objects that can be distinguished based on the detection result of red light to improve the overall discrimination accuracy. This is not limited to the case of sorting rice grains, but is common to the case of sorting any granular object. [Means for solving the problem]

[0005] The present invention has been made to solve the above-mentioned problems, and can be realized, for example, in the following forms.

[0006] According to a first aspect of the present invention, there is provided an optical sorting machine, comprising: a first red light source configured to emit red light toward a plurality of sorting objects being moved and disposed on a first side relative to a moving path of the plurality of sorting objects, a second red light source configured to emit red light toward the plurality of sorting objects being moved and disposed on a second side opposite to the first side, a first optical sensor disposed on the first side and configured to detect light associated with one of the plurality of sorting objects being moved during a plurality of scanning periods including a first scanning period and a second scanning period, a second optical sensor disposed on the second side and configured to detect light associated with one sorting object during a plurality of scanning periods, a determination unit configured to determine whether the one sorting object is a foreign object and / or a defective product based on signals acquired by the first optical sensor and the second optical sensor, and a light source control unit configured to control the first red light source and the second red light source. The light source control unit is configured to control the first red light source and the second red light source so that the first red light source and the second red light source are turned on during a first scanning period, and so that the first red light source is turned on and the second red light source is not turned on during a second scanning period.

[0007] According to this optical sorting machine, during a first scanning period, the first optical sensor on the first side detects reflected light (light reflected by the sorting object) based on light emitted from the first red light source on the first side and transmitted light (light transmitted through the sorting object) based on light emitted from the second red light source on the second side, and the second optical sensor on the second side detects transmitted light based on light emitted from the first red light source on the first side and reflected light based on light emitted from the second red light source on the second side. During a second scanning period, the first optical sensor on the first side detects only reflected light based on light emitted from the first red light source on the first side, and the second optical sensor on the second side detects only transmitted light based on light emitted from the first red light source on the first side. That is, the judgment unit can judge foreign matter and / or defective products using the reflected image (image represented by reflected light), the transmitted image (image represented by transmitted light), and the reflected and transmitted image (image represented by light in which reflected light and transmitted light are combined) for red light. Therefore, the number of types of defective products that can be identified increases compared to conventional optical sorting machines that use only reflected and transmitted images for red light. For example, when the object to be sorted is rice grains, green immature grains can be identified using the reflected and transmitted images for red light. The above "multiple scanning periods including the first scanning period and the second scanning period" is intended to include both a case where the "multiple scanning periods" are composed of only the "first scanning period" and the "second scanning period", and a case where the "multiple scanning periods" are composed of the "first scanning period", the "second scanning period", and any other scanning period.

[0008] According to the second aspect of the present invention, in the first aspect, the light source control unit is configured to control the first red light source and the second red light source such that there are on periods and off periods for each of the first red light source and the second red light source in the first scanning period, and there are on periods and off periods for the first red light source in the second scanning period. According to this aspect, power consumption can be reduced compared to when the first red light source and the second red light source are continuously on throughout the first scanning period, and compared to when the first red light source is continuously on throughout the second scanning period. In addition, since the temperature rise of the first red light source and the second red light source due to the shortened on-time can be suppressed, the characteristic change of the first red light source and the second red light source due to the temperature rise (more specifically, the change in the wavelength region of the emitted light) can be suppressed. Therefore, the judgment of foreign matter and / or defective products can be performed more stably.

[0009] According to the third aspect of the present invention, in the second aspect, the light source control unit is configured to control the first red light source and the second red light source such that, in the first scanning period, the turn-on period for each of the first red light source and the second red light source starts with a timing delayed from the start of the first scanning period, and in the second scanning period, the turn-on period for the first red light source starts with a timing delayed from the start of the second scanning period. According to this aspect, the first red light source and the second red light source are turned off at the start of the first scanning period. Also, the first red light source is turned off at the start of the second scanning period. Therefore, the light emitted from the first red light source and / or the second red light source in the Nth (N is an integer of 2 or more) scanning period is not detected in the N-1th scanning period. For example, if the first red light source and the second red light source are switched from off to on at the same time as the start of the Nth scanning period (assumed to correspond to the first scanning period) (in other words, the end of the N-1th scanning period), the light emitted from the first red light source and the second red light source at the same time as the start of the Nth scanning period may be mixed as noise into the detection result in the N-1th scanning period. On the other hand, according to this embodiment, such an event does not occur, and therefore the accuracy of judgment by the judgment unit can be improved.

[0010] The above-mentioned embodiments may be realized in combination with other known optical sorting machine configurations. For example, the optical sorting machine may include at least one light source that emits light other than red (e.g., green light and / or blue light) on the first side and / or the second side in any of the first to third embodiments. In this case, the first optical sensor and the second optical sensor may detect green light and / or blue light in addition to red light. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of an optical sorting machine according to a first embodiment of the present invention. [Diagram 2]4 is a timing chart showing the relationship between a scanning period of an optical sensor and the lighting timing of a light source. [Diagram 3] FIG. 11 is an explanatory diagram showing the relationship between one selection object and a scan number. [Figure 4] 10 is a timing chart showing the relationship between a scanning period of an optical sensor and the lighting timing of a light source according to a second embodiment. [Diagram 5] 13 is a timing chart showing the relationship between a scanning period of an optical sensor and the lighting timing of a light source according to a third embodiment. [Figure 6] 1 is a graph showing the spectral reflectance distribution of brown rice. [Figure 7] 1 is a graph showing the spectral reflectance distribution of coffee beans. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A. First embodiment: FIG. 1 is a schematic diagram showing a schematic configuration of an optical sorting machine (hereinafter simply referred to as a sorting machine) 10 according to a first embodiment of the present invention. In this embodiment, the sorting machine 10 is used to sort foreign matter (e.g., pebbles, mud, glass pieces, etc.) and defective products (e.g., immature grains, colored grains, etc.) from rice grains (more specifically, brown rice or polished rice) as a sorting target (hereinafter simply referred to as a target) 90. However, the target 90 is not limited to brown rice or polished rice, and may be any granular object. For example, the target 90 may be unhulled rice, wheat grains, beans (soybeans, chickpeas, edamame, etc.), resin (pellets, etc.), rubber pieces, etc.

[0013] As shown in FIG. 1, the sorting machine 10 includes an optical detection unit 20, a storage tank 71, a feeder 72, a chute 73, a non-defective product discharge gutter 74, a defective product discharge gutter 75, an ejector 76, and a control device 80. The control device 80 controls the overall operation of the sorting machine 10. The control device 80 also functions as a light source control unit 81 and a judgment unit 82. The functions of the control device 80 may be realized by a CPU executing a predetermined program, or may be realized by a dedicated circuit. The light source control unit 81 and the judgment unit 82 may be realized by one integrated device. For example, the light source control unit 81 and the judgment unit 82 may be two functions realized by one CPU. Alternatively, the light source control unit 81 and the judgment unit 82 may be realized as separate devices. The functions of the control device 80 will be described in detail later.

[0014] The storage tank 71 temporarily stores the object 90. The feeder 72 supplies the object 90 stored in the storage tank 71 onto the chute 73. The optical detection unit 20 irradiates the object 90 that has slid down the chute 73 with light and detects the light associated with the object 90 (specifically, the transmitted light that has passed through the object 90 and / or the reflected light that has been reflected by the object 90). The output from the optical detection unit 20, i.e., an analog signal that represents the intensity of the detected light, is converted into a digital signal by an AC / DC converter (not shown). This digital signal is input to the control device 80. Based on the detection result of the input light (i.e., the image), the control device 80 determines, as a process of the determination unit 82, whether the object 90 is a non-defective product (i.e., a rice grain with relatively high quality) or a foreign object (i.e., a non-rice grain) or a defective product (i.e., a rice grain with relatively low quality). This determination is performed for each of the objects 90.

[0015] If the object 90 is determined to be a foreign object or a defective product, the ejector 76 sprays air 77 toward the object 90. This blows the object 90 away, causing it to deviate from the falling trajectory from the chute 73 and be guided to the defective product discharge gutter 75. On the other hand, if the object 90 is determined to be a non-defective product, the air 77 is not sprayed. Therefore, the object 90 determined to be a non-defective product is guided to the non-defective product discharge gutter 74 without changing its falling trajectory.

[0016] Hereinafter, the optical detection unit 20 and the control device 80 will be described in detail. As shown in Fig. 1, the optical detection unit 20 includes a first red light source 30a, a second red light source 30b, a first green light source 40a, a second green light source 40b, a first blue light source 50a, a second blue light source 50b, a first optical sensor 60a, and a second optical sensor 60b.

[0017] The first red light source 30a emits a first red light 31a toward the multiple objects 90 being moved (i.e., falling from the chute 73). Similarly, the second red light source 30b emits a second red light 31b toward the multiple objects 90 being moved. The first green light source 40a emits a first green light 41a toward the multiple objects 90 being moved. Similarly, the second green light source 40b emits a second green light 41b toward the multiple objects 90 being moved. The first blue light source 50a emits a first blue light 51a toward the multiple objects 90 being moved. The second blue light source 50b emits a second blue light 51b toward the multiple objects 90 being moved.

[0018] In this embodiment, the first red light source 30a, the second red light source 30b, the first green light source 40a, the second green light source 40b, the first blue light source 50a, and the second blue light source 50b are LEDs. Although the number of these light sources is shown as one each in FIG. 1, the number of at least some of these light sources may be multiple.

[0019] The first optical sensor 60a and the second optical sensor 60b detect light associated with one of the multiple objects 90 being moved. In this embodiment, the first optical sensor 60a and the second optical sensor 60b are color CCD sensors and can detect red light, green light, and blue light individually. However, the first optical sensor 60a and the second optical sensor 60b may be other types of color sensors, such as a color CMOS sensor. Furthermore, although the first optical sensor 60a and the second optical sensor 60b are line sensors in this embodiment, they may be area sensors.

[0020] The first red light source 30a, the first green light source 40a, the first blue light source 50a and the first optical sensor 60a are arranged on one side (also called the front side) of the transfer path of the object 90 (in other words, the falling trajectory from the chute 73). On the other hand, the second red light source 30b, the second green light source 40b, the second blue light source 50b and the second optical sensor 60b are arranged on the other side (also called the rear side) of the transfer path of the object 90.

[0021] The first optical sensor 60a on the front side detects a first red light 31a (also referred to as a first reflected red light 31a) emitted from a first red light source 30a on the front side and reflected by the object 90, a first green light 41a (also referred to as a first reflected green light 41a) emitted from a first green light source 40a on the front side and reflected by the object 90, and a first blue light 51a (also referred to as a first reflected blue light) emitted from a first blue light source 50a on the front side and reflected by the object 90. It is possible to detect a second red light 31b (also referred to as second transmitted red light 31b) emitted from the second red light source 30b on the rear side and transmitted through the object 90, a second green light 41b (also referred to as second transmitted green light 41b) emitted from the second green light source 40b on the rear side and transmitted through the object 90, and a second blue light 51b (also referred to as second transmitted blue light 51b) emitted from the second blue light source 50b on the rear side and transmitted through the object 90.

[0022] The second optical sensor 60b on the rear side detects a second red light 31b (also referred to as a second reflected red light 31b) emitted from a second red light source 30b on the rear side and reflected by the object 90, a second green light 41b (also referred to as a second reflected green light 41b) emitted from a second green light source 40b on the rear side and reflected by the object 90, and a second blue light 51b (also referred to as a second reflected blue light 51b) emitted from a second blue light source 50b on the rear side and reflected by the object 90. ), a first red light 31a (also referred to as first transmitted red light 31a) emitted from the first red light source 30a on the front side and transmitted through the object 90, a first green light 41a (also referred to as first transmitted green light 41a) emitted from the first green light source 40a on the front side and transmitted through the object 90, and a first blue light 51a (also referred to as first transmitted blue light 51a) emitted from the first blue light source 50a on the front side and transmitted through the object 90.

[0023] As is well known, the first optical sensor 60a and the second optical sensor 60b perform multiple scans of one object 90. In other words, the first optical sensor 60a and the second optical sensor 60b detect light associated with one object 90 in each of multiple scan periods. A scan period is the time from the start to the end of one scan. By combining the images obtained in each scan, an entire image of the one object 90 is obtained. If the optical sensor is a CCD sensor, the "scan period" may be defined as the time from when the light receiving element starts accumulating charge to when the charge accumulation is completed. If the optical sensor is a CMOS sensor, the "scan period" may be defined as the time from when the light receiving element starts accumulating charge to when the accumulated charge is output.

[0024] The optical detection unit 20 is controlled by a control device 80. A light source control unit 81 controls the first red light source 30a, the second red light source 30b, the first green light source 40a, the second green light source 40b, the first blue light source 50a, and the second blue light source 50b according to a predetermined rule. FIG. 2 is a timing chart showing the relationship between the scanning period of the first optical sensors 60a and 60b and the lighting timing of these light sources. In FIG. 2, "R" represents the first red light source 30a or the second red light source 30b. Similarly, "G" represents the first green light source 40a or the second green light source 40b, and "B" represents the first blue light source 50a or the second blue light source 50b.

[0025] FIG. 3 is an explanatory diagram showing the relationship between one object 90 and the scan numbers (numbers indicating which scans have been performed) of the first optical sensor 60a and the second optical sensor 60b. As shown in FIG. 3, in this embodiment, image data is acquired by scanning one object 90 eight times (for the sake of simplicity, the example shows a number of times that is less than the actual number). The numbers 1 to 8 shown in FIG. 3 indicate the number of scans by which image data of the corresponding areas is acquired. For example, an area marked with "1" indicates that image data is acquired by the first scan. In FIG. 2, "Scan No." corresponds to the scan number shown in FIG. 3.

[0026] 2, the first red light source 30a on the front side is turned on for a predetermined time in each of all scanning periods (shown as ON in the figure). On the other hand, the second red light source 30b on the rear side is turned on for a predetermined time only in scanning periods having odd-numbered scanning numbers, and is not turned on at all in scanning periods having even-numbered scanning numbers. In this way, the first red light source 30a and the second red light source 30b are turned on so that there are scanning periods in which both are turned on and scanning periods in which only one of them (only the front side in this embodiment) is turned on.

[0027] The first green light source 40a and the first blue light source 50a on the front side are turned on for a predetermined time in each of all scanning periods, and similarly, the second green light source 40b and the second blue light source 50b on the rear side are turned on for a predetermined time in each of all scanning periods.

[0028] According to such a lighting mode, in the first optical sensor 60a on the front side, in the scanning period having an odd scanning number, the light obtained by combining the first reflected red light 31a and the second transmitted red light 31b, the light obtained by combining the first reflected green light 41a and the second transmitted green light 41b, and the light obtained by combining the first reflected blue light 51a and the second transmitted blue light 51b are individually detected. In other words, a red reflected-transmitted image, a green reflected-transmitted image, and a blue reflected-transmitted image are obtained through the first optical sensor 60a. In this application, the reflected image refers to an image represented only by reflected light. The transmitted image refers to an image represented only by transmitted light. The reflected-transmitted image refers to an image represented by light obtained by combining the reflected light and transmitted light.

[0029] In addition, the first optical sensor 60a on the front side detects the first reflected red light 31a, the light obtained by combining the first reflected green light 41a and the second transmitted green light 41b, and the light obtained by combining the first reflected blue light 51a and the second transmitted blue light 51b, respectively, during the scanning period having an even-numbered scanning number. In other words, a red reflected image, a green reflected-transmitted image, and a blue reflected-transmitted image are obtained through the first optical sensor 60a.

[0030] On the other hand, the second optical sensor 60b on the rear side detects the light obtained by combining the first transmitted red light 31a and the second reflected red light 31b, the light obtained by combining the first transmitted green light 41a and the second reflected green light 41b, and the light obtained by combining the first transmitted blue light 51a and the second reflected blue light 51b, respectively, during the scanning period having the odd scanning number. In other words, a red reflected-transmitted image, a green reflected-transmitted image, and a blue reflected-transmitted image are obtained through the second optical sensor 60b.

[0031] In addition, the second optical sensor 60b on the rear side detects the first transmitted red light 31a, the light obtained by combining the first transmitted green light 41a and the second reflected green light 41b, and the light obtained by combining the first transmitted blue light 51a and the second reflected blue light 51b, respectively, during the scanning period having an even-numbered scanning number. In other words, a red transmitted image, a green reflected-transmitted image, and a blue reflected-transmitted image are obtained via the second optical sensor 60b.

[0032] The determination unit 82 determines whether or not there is a foreign object and / or a defective product using the red reflection image, transmission image, and reflection-transmission image, the green reflection-transmission image, and the blue reflection-transmission image thus obtained. For example, whether or not the object 90 is a green immature grain is determined based on the front-side red reflection-transmission image (in other words, the red reflection-transmission image obtained via the first optical sensor 60a) constituted by the areas with odd-numbered scan numbers in Fig. 3 and the rear-side red reflection-transmission image (in other words, the red reflection-transmission image obtained via the second optical sensor 60b) constituted by the areas with odd-numbered scan numbers.

[0033] Also, whether or not the object 90 is a white spot is determined based on the rear-side red transmission image composed of the areas with the even-numbered scan numbers in Fig. 3. Although the front-side red reflection image composed of the areas with the even-numbered scan numbers is not used in this embodiment, both the rear-side red transmission image and the front-side red reflection image may be used in determining whether or not the object is a white spot.

[0034] In addition, whether or not the object 90 is a colored grain is determined based on the front side green reflection transmission image composed of the areas with the scan numbers 1 to 8, the front side blue reflection transmission image composed of the areas with the scan numbers 1 to 8, the rear side blue reflection transmission image composed of the areas with the scan numbers 1 to 8, and the rear side blue reflection transmission image composed of the areas with the scan numbers 1 to 8. These determinations are typically made by comparing the gradation value of the image data with a predetermined threshold value. For example, when the object 90 is a blue immature grain, the gradation value of the red transmission image is smaller than when the object 90 is a non-defective product. By utilizing this point, when the gradation value of the red transmission image is equal to or less than the threshold value, it can be determined that the object 90 is a blue immature grain. However, any known determination method can be adopted as the determination method by the determination unit 82. Instead of or in addition to the above-mentioned determination of a defective product, a foreign object determination may be performed.

[0035] As shown in FIG. 2, when any of the light sources is turned on (for example, when the second red light source 30b on the rear side is turned on in a scanning period having an odd scanning number), the light source control unit 81 controls the light source so that there is a turn-on period during which the light source is turned on and a turn-off period during which the light source is turned off in the scanning period. For example, in the example of FIG. 2, for the first red light source 30a on the front side, during the third scanning period, the turn-off period is from the start time T0 to the time T1 of the scanning period, the turn-on period is from the time T1 to the time T2, and the turn-off period is from the time T2 to the end time T3 of the scanning period. According to such a turn-on mode, it is possible to reduce the amount of power consumption compared to the case where the light source is turned on throughout the entire scanning period. In addition, since the temperature rise of the light source can be suppressed, it is possible to suppress the change in the wavelength region of the light emitted from the light source due to the temperature rise.

[0036] Furthermore, when turning on any of the light sources, the light source control unit 81 controls the light source so that the lighting period starts at a timing delayed from the start of the scanning period. For example, in the example of FIG. 2, in the third scanning period, the first red light source 30a on the front side is turned on so that the lighting period starts at a timing delayed from the start time point T0 of the scanning period (i.e., time point T1). In other words, at the start time point T0 of the scanning period, the first red light source 30a is turned off. Therefore, the first red light 31a emitted from the first red light source 30a on the front side in the third scanning period is not detected by the first optical sensor 60a or the second optical sensor 60b in the previous scanning period (i.e., the second scanning period). Specifically, if the first red light source 30a on the front side is turned on at the start time T0 of the third scanning period (which is also the end time of the second scanning period), the first red light 31a emitted at the same time as the start of the third scanning period may be mixed as noise into the detection result by the first optical sensor 60a or the second optical sensor 60b in the second scanning period. On the other hand, according to the present embodiment, such an event does not occur, so that the accuracy of the determination by the determination unit 82 can be improved. Here, the first red light source 30a on the front side has been described as an example, but this point is common to all light sources, not limited to the first red light source 30a on the front side.

[0037] According to the above-mentioned sorting machine 10, a scanning period in which both the first red light source 30a on the front side and the second red light source 30b on the rear side are turned on and a scanning period in which only one of them is turned on are set. Therefore, the judgment unit 82 can discriminate between white and green based on the red reflection image (or the reflection image and the transmission image) and can discriminate between green and green immature grains based on the red reflection transmission image. Therefore, compared with the conventional optical sorting machine that only discriminates between white and green using red light as described in Patent Document 1, the types of defective products that can be discriminated based on red light (in the above-mentioned example, green and green immature grains) can be increased. As a result, the overall discrimination accuracy can be improved.

[0038] In addition, since the first green light source 40a and the second green light source 40b are turned on during all scanning periods, the resolution of the green reflection-transmission image obtained through the first optical sensor 60a and the second optical sensor 60b is not reduced. This is also true for the blue reflection-transmission image. On the other hand, due to the above-mentioned lighting state of the first red light source 30a and the second red light source 30b, the red reflection-transmission image, the red transmission image, and the red reflection image obtained through the first optical sensor 60a and the second optical sensor 60b have half the resolution compared to the green reflection-transmission image and the blue reflection-transmission image. However, the blue immature grains identified based on the red reflection-transmission image and the white shrike identified based on the red transmission image are generally often discolored over the entire grain or over most of the grain. Therefore, the accuracy of identification is not significantly reduced due to the half resolution.

[0039] The above-described embodiment can be modified in various ways. For example, when the first red light source 30a and the second red light source 30b are turned on during at least one scanning period, they may be turned on continuously from the start time T0 to the end time T3 of the at least one scanning period. Also, the first green light source 40a, the second green light source 40b, the first blue light source 50a, and the second blue light source 50b may be turned on continuously throughout all scanning periods. Furthermore, instead of the lighting mode of the red light source 30a and the second red light source 30b shown in FIG. 2, a lighting mode may be adopted in which the first red light source 30a on the front side and the second red light source 30b on the rear side are turned on during scanning periods having odd scanning numbers, and the first red light source 30a is not turned on and the second red light source 30b is turned on during scanning periods having even scanning numbers. Alternatively, a lighting mode may be adopted in which the first red light source 30a is turned on and the second red light source 30b is not turned on in a scanning period having an odd scan number, and the first red light source 30a and the second red light source 30b are turned on in a scanning period having an even scan number. Alternatively, a lighting mode may be adopted in which the first red light source 30a is not turned on and the second red light source 30b is turned on in a scanning period having an odd scan number, and the first red light source 30a and the second red light source 30b are turned on in a scanning period having an even scan number.

[0040] B. Second embodiment: The second embodiment of the present invention will be described below. The second embodiment is different from the first embodiment in the lighting mode of each light source, and other points are the same as the first embodiment. Hereinafter, the second embodiment will be described only in terms of the points different from the first embodiment. FIG. 4 is a timing chart showing the relationship between the scanning period of the first optical sensors 60a, 60b according to the second embodiment and the lighting timing of each light source. In the example shown in FIG. 4, the lighting patterns can be roughly divided into a scanning period having a scanning number of 3N-2 (N is a natural number), a scanning period having a scanning number of 3N-1, and a scanning period having a scanning number of 3N. That is, in the second embodiment, three lighting patterns are repeated.

[0041] In the scanning period having the scanning number of 3N-2, the same lighting mode as the scanning period having the odd scanning number in the first embodiment is adopted. In the scanning period having the scanning number of 3N-1, the same lighting mode as the scanning period having the even scanning number in the first embodiment is adopted. In the scanning period having the scanning number of 3N, the first red light source 30a on the front side is not turned on, and the second red light source 30b on the rear side is turned on. That is, in the scanning period having the scanning number of 3N-1 and the scanning period having the scanning number of 3N, the turned-on red light source is switched between the front side and the rear side. As a result, in the scanning period having the scanning number of 3N, a red transmission image is obtained through the first optical sensor 60a, and a red reflection image is obtained through the second optical sensor 60b. In the example shown in FIG. 4, the scanning number is displayed up to 8 in accordance with the first embodiment, but the scanning number may be set in multiples of 3.

[0042] According to the second embodiment, a front side red transmission image, a front side red reflection image, a rear side red transmission image, and a rear side red reflection image can be obtained. This embodiment is effective when it is desired to improve the accuracy of the determination based on the red transmission image and / or the red reflection image by using both the front side and the rear side images.

[0043] The second embodiment described above can be modified in various ways. For example, when the lighting pattern of each light source in the scanning period having the scan number 1 in Fig. 4 is A, the lighting pattern of each light source in the scanning period having the scan number 2 is B, and the lighting pattern of each light source in the scanning period having the scan number 3 is C, Fig. 4 shows an example in which A, B, and C are repeated in this order, but the appearance order of each pattern can be arbitrarily set in six orders (specifically, A, B, C; A, C, B; B, A, C; B, C, A; C, A, B; C, B, A).

[0044] C. Third embodiment: The third embodiment of the present invention will be described below. The third embodiment is different from the first and second embodiments in the lighting mode of each light source, and other points are the same as the first and second embodiments. Hereinafter, only the points different from the first and second embodiments will be described for the third embodiment. FIG. 5 is a timing chart showing the relationship between the scanning period of the first optical sensors 60a, 60b according to the third embodiment and the lighting timing of each light source. In the example shown in FIG. 5, the lighting patterns can be roughly divided into a scanning period having a scanning number of 4M-3 (M is a natural number), a scanning period having a scanning number of 4M-2, a scanning period having a scanning number of 4M-1, and a scanning period having a scanning number of 4M. That is, in the third embodiment, four lighting patterns are repeated.

[0045] In the scanning period having a scan number of 4M-3, the same lighting mode as the scanning period having a scan number of 3N-2 in the second embodiment is adopted. In the scanning period having a scan number of 4M-2, the same lighting mode as the scanning period having a scan number of 3N-1 in the second embodiment is adopted. In the scanning period having a scan number of 4M-1, the same lighting mode as the scanning period having a scan number of 4M-3 in the third embodiment is adopted. In the scanning period having a scan number of 4M, the same lighting mode as the scanning period having a scan number of 3N in the second embodiment is adopted. That is, in the third embodiment, the type of image acquired is the same as in the second embodiment, but the resolution of the front side red reflection transmission image and the rear side red reflection transmission image is twice as high as that in the second embodiment. This embodiment is effective when it is desired to ensure a certain degree of resolution of the red reflection transmission image.

[0046] The third embodiment described above can be modified in various ways. For example, in the same manner as described for the modification of the second embodiment, the lighting patterns shown in Fig. 5 can be set in any order of appearance.

[0047] Although several embodiments of the present invention have been described above, the above-mentioned embodiments of the invention are intended to facilitate understanding of the present invention and do not limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof. In addition, within the scope of solving at least a part of the above-mentioned problems or achieving at least a part of the effects, any combination or omission of each component described in the claims and the specification is possible. For example, the lighting modes shown in Figs. 2, 4, and 5 are merely examples, and the embodiment according to the present invention can be modified to include a scanning period of any other lighting pattern as long as there is a scanning period in which both of the first red light source 30a on the front side and the second red light source 30b on the rear side are lit and a scanning period in which only one of them is lit. Furthermore, as long as there is a scanning period in which both of the first red light source 30a on the front side and the second red light source 30b on the rear side are lit and a scanning period in which only one of them is lit, it is possible to arbitrarily set the frequency of appearance of each of the multiple lighting patterns according to the resolution required for each image to be acquired. For example, in the first embodiment, the number of scanning periods during which both the first red light source 30a on the front side and the second red light source 30b on the rear side are turned on may be greater than the number of scanning periods during which only one of them is turned on, or vice versa. Furthermore, a conveyor may be used instead of the chute 73 as a means for transporting the object 90. Furthermore, any foreign object and / or defective product of any granular object may be determined using the red reflection image and / or transmission image and the red reflection / transmission image. For example, if the object 90 is coffee beans, yellow grains may be determined as defective products based on the red reflection image.

[0048] Furthermore, the wavelengths of the red light 31a, 31b emitted by the red light sources 30a, 30b can be appropriately set based on the type of the object 90 and the type of foreign matter and / or defective product to be identified. For example, when the object 90 is brown rice, if light sources emitting red light 31a, 31b having a peak wavelength of 645 nm or more and 675 nm or less are used as the red light sources 30a, 30b in consideration of the spectral reflectance distribution of brown rice shown in FIG. 6, green immature grains can be accurately identified based on the obtained red reflection image. Alternatively, when the object 90 is coffee beans, if light sources emitting red light 31a, 31b having a peak wavelength of 665 nm or more and 695 nm or less are used as the red light sources 30a, 30b in consideration of the spectral reflectance distribution of coffee beans shown in FIG. 7, very light yellow grains, light yellow grains, and dark yellow grains can be accurately identified based on the obtained red reflection image.

[0049] Furthermore, the red light sources 30a and 30b are not limited to LEDs, and may be any type of light source. For example, the red light sources 30a and 30b may be CCFLs (cold cathode fluorescent lamps). In this case, too, a CCFL having an appropriate peak wavelength (for example, if the object 90 is a coffee bean, 665 nm or more and 695 nm or less) may be selected depending on the type of object 90 and the type of foreign matter and / or defective product to be identified. [Explanation of symbols]

[0050] 10...Optical sorting machine 20...Optical detection section 30a...First red light source 30b...Second red light source 31a...First red light (first reflected red light, first transmitted red light) 31b...Second red light (second reflected red light, second transmitted red light) 40a...First green light source 40b...Second green light source 41a...First green light (first reflected green light, first transmitted green light) 41b...Second green light (second reflected green light, second transmitted green light) 50a...First blue light source 50b...Second blue light source 51a...First blue light (first reflected blue light, first transmitted blue light) 51b...Second blue light (second reflected blue light, second transmitted blue light) 60a...first optical sensor 60b...Second optical sensor 71...Storage tank 72...Feeder 73...Shoot 74...Good product discharge trough 75...Defective product discharge trough 76...Ejector 77...Air 80...Control device 81...Light source control unit 82...judgment section 90...Object

Claims

1. An optical sorting machine, comprising: a first red light source configured to emit red light toward the plurality of sorting objects being transported and disposed on a first side of a transport path of the plurality of sorting objects; a second red light source configured to emit red light toward the plurality of sorting objects being moved and disposed on a second side opposite the first side; a first optical sensor disposed on the first side and configured to detect light associated with one of the plurality of sorting objects being moved during a plurality of scan periods including a first scan period and a second scan period; a second optical sensor disposed on the second side and configured to detect light associated with the one sorting object during the plurality of scanning periods; and a determination unit configured to determine whether the one sorting object is a foreign object and / or a defective product based on signals acquired by the first optical sensor and the second optical sensor; a light source controller configured to control the first red light source and the second red light source; Equipped with the light source control unit is configured to control the first red light source and the second red light source so that the first red light source and the second red light source are turned on during the first scanning period, and the first red light source is turned on and the second red light source is not turned on during the second scanning period; The determination unit is configured to determine whether or not there is a foreign object and / or a defective product based on a reflected / transmitted image acquired by each of the first optical sensor and the second optical sensor during the first scanning period, a reflected image acquired by the first optical sensor during the second scanning period, and a transmitted image acquired by the second optical sensor during the second scanning period. Optical sorting machine.

2. An optical sorting machine, comprising: a first red light source configured to emit red light toward the plurality of sorting objects being transported and disposed on a first side of a transport path of the plurality of sorting objects; a second red light source configured to emit red light toward the plurality of sorting objects being moved and disposed on a second side opposite the first side; a first optical sensor disposed on the first side and configured to detect light associated with one of the plurality of sorting objects being moved during a plurality of scan periods including a first scan period and a second scan period; a second optical sensor disposed on the second side and configured to detect light associated with the one sorting object during the plurality of scanning periods; and a determination unit configured to determine whether the one sorting object is a foreign object and / or a defective product based on signals acquired by the first optical sensor and the second optical sensor; a light source controller configured to control the first red light source and the second red light source; Equipped with the light source control unit is configured to control the first red light source and the second red light source so that the first red light source and the second red light source are turned on during the first scanning period, and the first red light source is turned on and the second red light source is not turned on during the second scanning period; The light source control unit is configured to control the first red light source and the second red light source such that, during the first scanning period, there are on periods and off periods for each of the first red light source and the second red light source, and, during the second scanning period, there are on periods and off periods for the first red light source. Optical sorting machine.

3. 3. The optical sorting machine according to claim 2, The light source control unit is configured to control the first red light source and the second red light source such that, during the first scanning period, the lighting period for each of the first red light source and the second red light source starts at a timing delayed from the start of the first scanning period, and, during the second scanning period, the lighting period for the first red light source starts at a timing delayed from the start of the second scanning period. Optical sorting machine.

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