Measuring device and sorting device

Abstract

In optical measuring devices or sorting devices, it is possible to easily adjust the light intensity to suppress the occurrence of shadows in images while ensuring sufficient illumination. [Solution] The measuring device comprises a light source configured to irradiate light onto an object being transported along a transport path; an optical sensor configured to detect light irradiated from the light source and associated with an object located at a detection position on the transport path; an identification unit configured to identify the state of an object based on a signal acquired by the optical sensor with respect to the light associated with the object; and a diffuse-transmitting member disposed between the light source and the detection position, extending over regions corresponding to the detection position, the region upstream of the detection position, and the region downstream of the detection position on the transport path, the diffuse-transmitting member having a flat surface on the side opposite to the detection position.

Description

Technical Field

[0001] The present invention relates to an optical measuring device and a sorting device.

Background Art

[0002] When light is irradiated from a light source onto an object to be sorted (hereinafter simply referred to as an object) being transported on a transport path, an optical sorting device (hereinafter simply referred to as a sorting device) that identifies and removes foreign matter and defective products contained in the object using an image obtained by an optical sensor has been conventionally known. In such a sorting device, a granular material (for example, a transparent resin pellet) that is likely to cause a shadow in the image when imaged by an optical sensor may be used as the object. The occurrence of such a shadow leads to a decrease in the identification accuracy of foreign matter and defective products, and thus the sorting accuracy.

[0003] For this reason, Patent Documents 1 and 2 below disclose a sorting device having a configuration in which a shadow is less likely to occur in an image. In this sorting device, light is irradiated from a light source onto an object through a dome-shaped diffusing transmission member. That is, the light diffused through the dome-shaped diffusing transmission member is irradiated onto the object. As a result, more light can be irradiated onto the object from more directions compared to the case where the light emitted from the light source is directly irradiated onto the object, and the occurrence of a shadow is less likely. In this sorting device, further, a light shielding plate is disposed outside the light source, and a hood cylinder member having light shielding properties is disposed between the light sources. The optical sensor detects light through a path passing through the hood cylinder member from the detection location of the object. This prevents noise light from entering from the outside and enables a clearer image to be obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] However, the sorting device described above still has room for improvement in terms of reducing the occurrence of shadows in images. For example, since the diffuse transmission member has a dome shape, the direction of light diffusion is complex. Therefore, adjusting the light intensity (hereinafter also simply referred to as light intensity adjustment) to ensure sufficient illumination and suppress variations in brightness between light irradiation directions to prevent (or reduce the occurrence of) shadows in images requires delicate and highly difficult work. As a result, there may be cases where effective light intensity adjustment cannot be performed. In addition, since the hood cylinder member is positioned to partially block the light from the light source, localized biases in brightness may occur. This makes light intensity adjustment even more difficult. Moreover, since the hood cylinder member is located near the light source, there may be constraints on the upper limit of light intensity from the standpoint of preventing the hood cylinder member from overheating. This also makes light intensity adjustment even more difficult. For these reasons, there is a need for the development of a technology that can easily adjust the light intensity to suppress the occurrence of shadows in images by suppressing variations in brightness between light irradiation directions while ensuring sufficient illumination. The above problems apply not only to sorting devices but also to measuring devices used to optically measure the condition of objects. [Means for solving the problem]

[0006] The present invention has been made to solve at least some of the above-mentioned problems and can be realized, for example, in the following forms.

[0007] According to a first embodiment of the present invention, a measuring device for measuring the state of a granular object is provided. The measuring device comprises a light source configured to irradiate light onto an object being transported along a transport path; an optical sensor configured to detect light irradiated from the light source and associated with an object located at a detection position on the transport path; an identification unit configured to identify the state of an object based on a signal acquired by the optical sensor with respect to the light associated with the object; and a diffuse-transmitting member disposed between the light source and the detection position, extending over regions corresponding to the detection position, the region upstream of the detection position, and the region downstream of the detection position, respectively, and having a flat surface on the side opposite to the detection position.

[0008] According to this measuring device, the light source illuminates the object via diffuse-transmitting members positioned across areas corresponding to the detection position, the area upstream of the detection position, and the area downstream of the detection position. As a result, the light transmitted through the diffuse-transmitting members is diffused and illuminates the object from various directions. Therefore, compared to cases where light is illuminated to the object via diffuse-transmitting members, shadows are less likely to occur in the image of the object. Furthermore, the diffuse-transmitting members have a flat surface on the side opposite to the detection position. Therefore, compared to using dome-shaped diffuse-transmitting members, the direction of light diffusion is simpler, and light intensity adjustment becomes easier. Moreover, compared to using dome-shaped diffuse-transmitting members, it becomes possible to position the light source closer to the detection position. Therefore, even if the diffuse-transmitting members have a flat surface, meaning their diffusion performance is inferior to that of dome-shaped diffuse-transmitting members, sufficient illuminance can be ensured. Consequently, while ensuring sufficient illuminance, it is possible to easily adjust the light intensity to suppress variations in brightness between light irradiation directions and reduce the occurrence of shadows in the image. In this specification, "illuminance" means the amount of light per unit area of ​​an object at the detection location (unit: lux), "luminous intensity" means the strength of light emitted in a specific direction (unit: candela), and "luminous quantity" means the luminous flux of a light source (unit: lumens).

[0009] According to a second embodiment of the present invention, in the first embodiment, the light source includes a first light source located at a first position relative to the detection position and a second light source located at a second position different from the first position relative to the detection position. The diffuse transmission member includes a first diffuse transmission member disposed between the first light source and the detection position and a second diffuse transmission member disposed between the second light source and the detection position. In this embodiment, since light is irradiated onto the object from two positions relative to the detection position via the first diffuse transmission member and the second diffuse transmission member, respectively, shadows are less likely to occur.

[0010] According to a third embodiment of the present invention, in the second embodiment, the first position is located on one side of the transport path, and the second position is located on the opposite side of the transport path. The first diffuse-transmitting member and the second diffuse-transmitting member are arranged to face each other with the transport path in between. In this embodiment, light is irradiated onto the object from both sides of the transport path via the first diffuse-transmitting member and the second diffuse-transmitting member, respectively, making it even less likely for shadows to occur.

[0011] According to a fourth embodiment of the present invention, in the third embodiment, the optical sensor includes a first optical sensor located at a first position and a second optical sensor located at a second position. The first diffuse-transmitting member and the second diffuse-transmitting member are arranged non-parallel to each other. In this embodiment, the first diffuse-transmitting member and the second diffuse-transmitting member can function as a background. Specifically, the portion of the second diffuse-transmitting member that intersects with the extension of the optical axis of the first optical sensor functions as a background for the first optical sensor, and the portion of the first diffuse-transmitting member that intersects with the extension of the optical axis of the second optical sensor functions as a background for the second optical sensor. Therefore, there is no need to provide a separate background, and the measuring device can be made more compact and less expensive.

[0012] According to a fifth embodiment of the present invention, in any of the second to fourth embodiments, the first light source includes a first intermediate light source positioned at or near an intermediate position corresponding to the detection position, and a first downstream light source positioned at a downstream position corresponding to a downstream region. In this embodiment, since light is emitted from both the intermediate and downstream positions, the object is illuminated from more directions. Therefore, shadows are less likely to occur, and the amount of light can be adjusted more easily.

[0013] According to a sixth embodiment of the present invention, in the fifth embodiment, the first light source includes a first upstream light source positioned at an upstream location corresponding to the upstream region. In this embodiment, since light is emitted from the upstream position as well, the object is illuminated from more directions. Therefore, shadows are less likely to occur, and the amount of light can be adjusted more easily.

[0014] According to a seventh embodiment of the present invention, in any of the second to sixth embodiments, the light source includes a third light source. The diffuse-transmitting member is positioned between the third light source and the detection position so as to partially cover the gap between the upper edge of the first diffuse-transmitting member and the upper edge of the second diffuse-transmitting member, and includes a third diffuse-transmitting member angled to intersect the transport path at a larger angle than the first and second diffuse-transmitting members. In this embodiment, the third light source and the third diffuse-transmitting member sufficiently illuminate the object from an upward-to-downward direction with a small angle to the transport path. Therefore, shadows are less likely to occur, and light intensity adjustment becomes easier.

[0015] According to the eighth embodiment of the present invention, in the seventh embodiment, including the sixth embodiment, the angle formed in the upstream region by the straight line connecting the first upstream light source and the detection position and the transport path is 45 degrees or more. The angle formed in the upstream region by the straight line connecting the third light source and the detection position and the transport path is 35 degrees or less. According to this embodiment, the object is sufficiently illuminated with light from more directions.

[0016] According to the ninth embodiment of the present invention, in any of the fifth to eighth embodiments, the first intermediate light source includes two first intermediate light sources spaced apart so as to sandwich a detection position in the direction in which the transition path extends. Each of the two first intermediate light sources is oriented such that the optical axis of each of the two first intermediate light sources is perpendicular to the first diffuse-transmitting member. This embodiment makes it possible to avoid specular reflection of light from the first intermediate light sources by the object (or the object or the first transparent member when the ninth embodiment is combined with the fourteenth embodiment described later). This prevents excessive brightness of light in certain directions, thus avoiding excessive whitening of parts of the image. Consequently, it is possible to obtain an image that can be identified with higher accuracy.

[0017] According to the tenth embodiment of the present invention, in the sixth embodiment, which includes the fourth and fifth embodiments, and in any of the seventh to ninth embodiments, which include the fourth and sixth embodiments, the light intensity of the first intermediate light source is smaller than the light intensity of the first upstream light source and the first downstream light source. Generally, light irradiated onto an object from the first intermediate light source is easily detected as transmitted light by the second optical sensor, so the amount of charge of the light detected by the second optical sensor is more greatly influenced by transmitted light than by reflected light. However, according to this embodiment, the transmitted light and reflected light detected by the second optical sensor can be made uniform. Therefore, an image that can be identified with higher accuracy can be obtained.

[0018] According to the eleventh embodiment of the present invention, in the sixth embodiment, the seventh to ninth embodiments including the sixth embodiment, and the tenth embodiment, the distance between the first intermediate light source and the first diffuse-transmitting member is greater than the distance between the first upstream light source and the first downstream light source and the first diffuse-transmitting member, respectively. According to this embodiment, for the same reasons as in the tenth embodiment, an image that can be identified with higher accuracy can be obtained.

[0019] According to the twelfth embodiment of the present invention, in any of the sixth embodiment, the seventh to ninth embodiments including the sixth embodiment, the tenth embodiment, and the eleventh embodiment, the first upstream light source is oriented so that the optical axis of the first upstream light source is directed toward the detection position. The first downstream light source is oriented so that the optical axis of the first downstream light source is directed toward the detection position. With this embodiment, compared to the case where the optical axes of the first upstream light source and the optical axes of the first downstream light source are oriented perpendicular to the first diffuse transmission member, the background of the first optical sensor can be brightened while ensuring illumination that is less likely to produce shadows in the image. As a result, the analog gain of the first optical sensor can be reduced, and an image with less noise can be obtained.

[0020] According to the thirteenth embodiment of the present invention, in the fourth embodiment and any of the fifth to twelfth embodiments including the fourth embodiment, the first diffuse-transmitting member has a first through-hole in a region corresponding to the field of view of the first optical sensor. The second diffuse-transmitting member has a second through-hole in a region corresponding to the field of view of the second optical sensor. The measuring device includes a first half-mirror covering the first through-hole and a second half-mirror covering the second through-hole. According to this embodiment, the second through-hole is less likely to appear as a shadow in the image acquired by the first optical sensor, and the first through-hole is less likely to appear as a shadow in the image acquired by the second optical sensor.

[0021] According to a fourteenth embodiment of the present invention, in any of the second to thirteenth embodiments, the measuring device includes a first transparent member that partitions the transport path and a first light source, and a second transparent member that partitions the transport path and a second light source. The first diffuse-transmitting member is attached to the first transparent member, and the second diffuse-transmitting member is attached to the second transparent member. In this embodiment, the first light source and the second light source are not exposed to dust generated in the transport path. Furthermore, the first diffuse-transmitting member and the second diffuse-transmitting member can be attached with a simple configuration.

[0022] According to a 15th embodiment of the present invention, in the 14th embodiment, the first diffuse permeable member is located on the side of the first transparent member where the first light source is located. The second diffuse permeable member is located on the side of the second transparent member where the second light source is located. In this embodiment, the first diffuse permeable member and the second diffuse permeable member are not exposed to dust generated in the transport path. Therefore, dust cleaning becomes easier.

[0023] According to the sixteenth embodiment of the present invention, in the fourteenth or fifteenth embodiment, the light source includes a third light source. The diffuse permeable member is positioned between the third light source and the detection position so as to partially cover the gap between the upper edge of the first diffuse permeable member and the upper edge of the second diffuse permeable member, and includes a third diffuse permeable member angled to intersect the transport path at a larger angle than the first and second diffuse permeable members. The measuring device includes a cleaning device configured to clean the first and second transparent members. The third diffuse permeable member includes two third diffuse permeable members positioned spaced apart. The cleaning device is configured to be movable between a retracted position, which is moved away from the transport path, and a cleaning position, which is positioned between the first and second transparent members, utilizing the gap between the two third diffuse permeable members. According to this embodiment, the same effects as the seventh embodiment can be obtained. Furthermore, when the measuring device is not in operation, dust adhering to the first and second transparent members can be cleaned using the gap between the two third diffuse permeable members.

[0024] According to the seventeenth aspect of the present invention, in any one of the fourth aspect, the fifth to twelfth aspects including the fourth aspect, the thirteenth aspect, and the fourteenth to sixteenth aspects including the fourth aspect, the first diffusion transmissive member has a first through-hole in a region corresponding to the visual field of the first optical sensor. The second diffusion transmissive member has a second through-hole in a region corresponding to the visual field of the second optical sensor. The measuring device includes a first half mirror disposed on the optical axis of the first optical sensor passing through the first through-hole, a second half mirror disposed on the optical axis of the second optical sensor passing through the second through-hole, a first auxiliary diffusion transmissive member, and a second auxiliary diffusion transmissive member. The measuring device is configured such that light transmitted through the first auxiliary diffusion transmissive member and reflected by the first half mirror passes through the first through-hole, and light transmitted through the second auxiliary diffusion transmissive member and reflected by the second half mirror passes through the second through-hole. According to this aspect, the luminous intensity of the light from the first light source reaching the detection position through the first through-hole and the luminous intensity of the light from the first light source reaching the detection position through a portion of the first diffusion transmissive member where the first through-hole is not formed can be adjusted equally. Similarly, the luminous intensity of the light from the second light source reaching the detection position through the second through-hole and the luminous intensity of the light from the second light source reaching the detection position through a portion of the second diffusion transmissive member where the second through-hole is not formed can be adjusted equally. Therefore, shadows caused by the first through-hole and the second through-hole are less likely to occur in the image.

[0025] According to the eighteenth aspect of the present invention, a sorting device is provided. This sorting device includes the measuring device according to any one of the first to seventeenth aspects, and a sorting unit configured to sort an object based on the identification result of the identification unit. According to this sorting device, the same effects as those of any one of the first to seventeenth aspects can be obtained.

Brief Description of the Drawings

[0026] [Figure 1] It is a schematic diagram showing a schematic configuration of a sorting device according to the first embodiment. [Figure 2] It is a schematic diagram showing a schematic configuration of a sorting device according to the second embodiment. [Figure 3] This is a schematic diagram showing the layout of the cleaning equipment. [Figure 4] This is a schematic diagram showing the general configuration of the sorting apparatus according to the third embodiment. [Figure 5] This is a partially schematic diagram showing the general configuration of a sorting apparatus according to the fourth embodiment. [Figure 6] This is a partially schematic diagram showing the general configuration of the sorting apparatus according to the fifth embodiment. [Figure 7] This is a schematic diagram showing the general configuration of the measuring device according to the sixth embodiment. [Modes for carrying out the invention]

[0027] Referring to Figure 1, the schematic configuration of an optical sorting device (hereinafter simply referred to as the sorting device) 10 according to an exemplary first embodiment will be described. Figure 1 is a schematic diagram showing the schematic configuration of the sorting device 10. In this embodiment, the sorting device 10 is used to sort granular sorting targets (hereinafter simply referred to as targets) 11. In this embodiment, the targets 11 are opaque resin pellets. However, the targets 11 may be various granular materials such as translucent resin pellets, transparent resin pellets, glass fragments, minerals, crushed plastics, etc.

[0028] The sorting device 10 includes a storage tank 21, a feeder 22, a belt conveyor 23, a good product discharge trough 24, a defective product discharge trough 25, a sorting unit 26, a first light source 30, a second light source 40, a third light source 50, a first optical sensor 60, a second optical sensor 61, and a controller 90. The controller 90 controls the overall operation of the sorting device 10. In this embodiment, the controller 90 includes a CPU (processor) and memory, and realizes various functions by executing a predetermined program stored in the memory. The controller 90 also functions as an identification unit 91. Details of the identification unit 91 will be described later. The functions of the controller 90 may be realized by a dedicated circuit, or by a combination of the CPU and a dedicated circuit.

[0029] The storage tank 21 temporarily stores the objects 11. The feeder 22 supplies the objects 11 stored in the storage tank 21 onto one end of a belt conveyor 23, which is an example of an object transport means. The objects 11 supplied onto the belt conveyor 23 are transported along the belt conveyor 23 and fall from the other end of the belt conveyor 23. The objects 11 released into the air from the other end of the belt conveyor 23 fall in a parabolic trajectory. This falling trajectory of the objects 11 is also called the transport path 14 of the objects 11. The belt conveyor 23 has a predetermined width that allows a large number of objects 11 to fall simultaneously.

[0030] The first light source 30, the second light source 40, and the third light source 50 irradiate light onto the object 11 being transported along the transport path 14. Each of the light sources 30, 40, and 50 is a light source unit for irradiating visible light. In this embodiment, each of the light sources 30, 40, and 50 is equipped with so-called color LEDs and is capable of emitting red light, green light, and blue light. More specifically, each of the light sources 30, 40, and 50 is equipped with a red-emitting LED chip, a green-emitting LED chip, and a blue-emitting LED chip, and each color LED chip can be lit individually or in any combination of two or more colors. Which color of light the light sources 30, 40, and 50 irradiate can be changed according to the properties of the object 11 and the type of defective product to be identified by the identification unit 91, which will be described later. However, the light emitted by each of the light sources 30, 40, and 50 can be one or more types of visible light having any wavelength range. For example, each of the light sources 30, 40, and 50 may be a white LED that emits white light.

[0031] The first optical sensor 60 and the second optical sensor 61 detect light irradiated from light sources 30, 40, and 50 and associated with the object 11 located at the detection position 15. The detection position 15 is a position on the transport path of the object 11 where the object 11 is optically detected by the first optical sensor 60 and the second optical sensor 61.

[0032] The first light source 30 and the first optical sensor 60 are located at a first position relative to the detection position 15. The second light source 40 and the second optical sensor 61 are located at a second position different from the first position relative to the detection position 15. The third light source 50 is located at a third position different from the first and second positions relative to the detection position 15. In this embodiment, the first and third positions are on one side (also called the front side) of the transport path 14, and the second position is on the other side (also called the rear side) of the transport path 14. In this embodiment, each of the first optical sensor 60 and the second optical sensor 61 is a line sensor having a plurality of light-receiving elements arranged linearly in the width direction of the belt conveyor 23. In this embodiment, each of the optical sensors 60 and 61 is a monochrome CCD sensor. Each of the optical sensors 60 and 61 may be an area sensor. Also, each of the optical sensors 60 and 61 may be a color CCD sensor capable of individually detecting red light, green light, and blue light, respectively. The optical sensors 60 and 61 may be other types of sensors, such as CMOS sensors. The light sources 30 and 40 are arranged in the width direction of the belt conveyor 23 over a wider area than the field of view of the optical sensors 60 and 61.

[0033] In this embodiment, the "light associated with the object 11" detected by the optical sensors 60 and 61 refers to transmitted light that has passed through the object 11, and / or reflected light that has been reflected by the object 11. Specifically, the first optical sensor 60 on the front side can detect either or both of the light that is irradiated from the front side and reflected by the object 11, and the light that is irradiated from the rear side and passed through the object 11. The second optical sensor 61 on the rear side can detect either or both of the light that is irradiated from the rear side and reflected by the object 11, and the light that is irradiated from the front side and passed through the object 11. What kind of light is detected by the first optical sensor 60 and the second optical sensor 61 depends on the relationship between the scanning period of the first optical sensor 60 and the second optical sensor 61 and the lighting patterns of the first light source 30 and the second light source 40.

[0034] The outputs from the first optical sensor 60 and the second optical sensor 61, i.e., analog signals representing the detected light intensity, are amplified by an AC / DC converter (not shown) at a predetermined gain and then converted into digital signals. These digital signals are input to the controller 90 as image data. The controller 90, as part of the processing of the identification unit 91, identifies the state of the object 11 based on the input image. Such identification is performed for each of the objects 11.

[0035] In this embodiment, the state determined by the controller 90 includes at least one of a color state (in other words, an optical state) and a shape and / or dimensional state. The state also includes at least one of a feature quantity represented by a physical quantity and a quality determined based on the feature quantity.

[0036] The color-related feature quantities include the color gradation values ​​of each pixel in the image representing the object 11. The shape-related and / or dimensional feature quantities may include, for example, the area, height, width, perimeter length, and at least one of the circularity of the whole and / or part of the object 11.

[0037] In this embodiment, "quality" includes, for example, a distinction between good products (i.e., resin pellets of relatively good quality) and defective products (i.e., resin pellets of relatively low quality, and / or foreign matter). "Quality" may also include a distinction between items to be removed in the sorting unit 26 and items that should not be removed. Furthermore, "quality" may include quality determined based on color and quality determined based on shape and / or dimensional.

[0038] In this embodiment, the controller 90 determines whether the object 11 is a good product or a defective product by comparing the characteristic quantity of the color state (in other words, the grayscale value of the image data) with a predetermined threshold (in other words, based on whether the characteristic quantity of the color state is within a predetermined normal range). Such a determination may be made based on representative values ​​of the grayscale values ​​of multiple pixels constituting the image of the object 11 (e.g., mean, median, maximum, minimum, etc.). Alternatively, defective products may include objects 11 having partial defects of a predetermined size or larger. Such partial defects may be determined based on the fact that the number of pixels among the multiple pixels constituting the image of the object 11 whose grayscale values ​​are not within the normal range is greater than or equal to a predetermined number (in other words, the area of ​​the defective part is greater than or equal to a predetermined value). When monochrome sensors are used for the optical sensors 60, 61 as in this embodiment, the object 11, which is an opaque resin pellet, will appear white in the image if it is a good product and black if it is a defective product.

[0039] Furthermore, in this embodiment, the controller 90 determines whether the object 11 is a good product or a defective product by comparing the feature quantities of the shape and / or dimensional state with a predetermined threshold (in other words, based on whether the feature quantities of the shape and / or dimensional state are within a predetermined normal range).

[0040] The sorting unit 26 sorts the objects 11 based on the state determined by the controller 90. This sorting is performed by a trajectory changing operation to alter the trajectory of a specific object 11. Specifically, the sorting unit 26 includes a plurality of injection nozzles 27 and a plurality of valves 28 arranged in the width direction of the belt conveyor 23. In Figure 1, for the sake of simplicity, the number of injection nozzles 27 and the number of valves 28 are shown to be the same, but in reality, the correspondence between the number of injection nozzles 27 and the number of valves 28 depends on the number of openings that the injection nozzles 27 have.

[0041] More specifically, the controller 90 determines a specific object 11 to be subjected to a trajectory change operation based on the determined state, and outputs a control signal to a valve 28 at the position corresponding to the specific object 11. In this embodiment, the specific object 11 is an object 11 identified as a defective product. In response to the above control signal, the valve 28 is opened, and air 29 is injected from the corresponding opening of the corresponding injection nozzle 27. The specific object 11 is blown away by the air 29, deviating from its falling trajectory from the belt conveyor 23 and guided to the defective product discharge trough 25 (shown as object 12 in Figure 1). On the other hand, air 29 is not injected into objects 11 determined to be good products. Therefore, objects 11 determined to be good products are guided to the good product discharge trough 24 without changing their falling trajectory (shown as object 13 in Figure 1). In this way, the objects 11 are sorted into good products and defective products. The above-mentioned specific object 11 can be set arbitrarily. For example, air 29 may be sprayed onto an object 11 that has been identified as a good product (so-called reverse spraying).

[0042] The sorting device 10 further comprises a first transparent member 70, a second transparent member 71, a third transparent member 72, a first diffuse-transmitting member 80, a second diffuse-transmitting member 81, and a third diffuse-transmitting member 82. The first transparent member 70 partitions the transfer path 14 from the first light source 30. The second transparent member 71 partitions the transfer path 14 from the second light source 40. The third transparent member 72 partitions the transfer path 14 from the third light source 50. Each of the transparent members 70, 71, and 72 is in the form of a transparent flat plate. With this configuration, the light sources 30, 40, and 50 are not exposed to dust generated in the transfer path 14.

[0043] The first diffusion-permeable member 80, the second diffusion-permeable member 81, and the third diffusion-permeable member 82 are arranged as a whole over regions corresponding to the detection position 15 on the transport path 14, the region upstream of the detection position 15 on the transport path 14, and the region downstream of the detection position 15 on the transport path 14. Similarly, the first diffusion-permeable member 80 and the second diffusion-permeable member 81 are also arranged over regions corresponding to the detection position 15, the region upstream of the detection position 15, and the region downstream of the detection position 15, respectively. In this embodiment, the first diffusion-permeable member 80, the second diffusion-permeable member 81, and the third diffusion-permeable member 82 are attached to the first transparent member 70, the second transparent member 71, and the third transparent member 72, respectively. Therefore, there is no need to provide separate members to support the diffusion-permeable members 80, 81, and 82, and the diffusion-permeable members 80, 81, and 82 can be attached in a simple configuration.

[0044] The first diffuse-transmitting member 80 is positioned between the first light source 30 and the detection position 15. Therefore, the first light source 30 irradiates the object 11 with light via the first diffuse-transmitting member 80. The second diffuse-transmitting member 81 is positioned between the second light source 40 and the detection position 15. Therefore, the second light source 40 irradiates the object 11 with light via the second diffuse-transmitting member 81. The third diffuse-transmitting member 82 is positioned between the third light source 50 and the detection position 15. Therefore, the third light source 50 irradiates the object 11 with light via the third diffuse-transmitting member 82. In this specification, "diffuse-transmitting member" refers to a member that causes diffuse transmission (i.e., transmission other than forward transmission). Diffuse transmission can be caused, for example, by the material of the member or by the uneven shape of the surface on the transmission side (opposite the incident side).

[0045] In this embodiment, the diffusion-permeable members 80, 81, and 82 are sheet-like. "Sheet-like" means a thin member form such as a thin plate or seal. In this embodiment, both sides of the diffusion-permeable members 80, 81, and 82 (the surface on the detection position 15 side and the surface opposite to the detection position 15) are flat. In an alternative embodiment, the surface opposite to the detection position 15 may be flat, and the surface on the detection position 15 side may have irregularities.

[0046] The first diffusion permeable member 80 and the second diffusion permeable member 81 are arranged facing each other with the transport path 14 in between. In this embodiment, the first diffusion permeable member 80 and the second diffusion permeable member 81 are arranged non-parallel to each other. The third diffusion permeable member 82 is arranged to partially cover the gap between the upper edge 80a of the first diffusion permeable member 80 and the upper edge 81a of the second diffusion permeable member 81, and is angled to intersect the transport path 14 at a larger angle than the first diffusion permeable member 80 and the second diffusion permeable member 81. In this embodiment, the third diffusion permeable member 82 is located on the front side.

[0047] The first diffuse-transmitting member 80 has a first through-hole 83 in a region corresponding to the field of view of the first optical sensor 60. The second diffuse-transmitting member 81 has a second through-hole 84 in a region corresponding to the field of view of the second optical sensor 61. The first through-hole 83 and the second through-hole 84 are each slightly larger than the fields of view of the first optical sensor 60 and the second optical sensor 61. As a result, the first optical sensor 60 and the second optical sensor 61 can acquire a clear image of the object 11 without going through the first diffuse-transmitting member 80 and the second diffuse-transmitting member 81.

[0048] The first diffuse-transmitting member 80 is located on the side of the first transparent member 70 where the first light source 30 is located. The second diffuse-transmitting member 81 is located on the side of the second transparent member 71 where the second light source 40 is located. The third diffuse-transmitting member 82 is located on the side of the third transparent member 72 where the third light source 50 is located. As a result, the diffuse-transmitting members 80, 81, and 82 are not exposed to dust generated in the transport path 14. This eliminates the need to clean dust from the first diffuse-transmitting member 80 and the second diffuse-transmitting member 81, which have the first through-hole 83 and the second through-hole 84, respectively (i.e., it is sufficient to clean dust only from the first transparent member 70 and the second transparent member 71, which are flat overall), thus making cleaning easier.

[0049] In this embodiment, the angle at which the optical axis 60a of the first optical sensor 60 intersects the first transparent member 70 and the first diffuse-transmitting member 80 is equal to the angle at which the optical axis 61a of the second optical sensor 61 intersects the second transparent member 71 and the second diffuse-transmitting member 81. In this embodiment, this angle is 90 degrees, but it may be any other angle. In alternative embodiments, these two angles may be different.

[0050] The sorting device 10 further includes a first half mirror 85 and a second half mirror 86. The first half mirror 85 is positioned on the optical axis 60a of the first optical sensor 60 so as to cover the first through hole 83 of the first diffuse-transmitting member 80. The first half mirror 85 is positioned on the opposite side of the detection position 15 from the first diffuse-transmitting member 80 and is positioned perpendicular to the optical axis 60a of the first optical sensor 60. In an alternative embodiment, the first half mirror 85 may be positioned on the opposite side of the detection position 15 from the first transparent member 70 and on the side of the first diffuse-transmitting member 80 closer to the detection position 15. That is, the first half mirror 85 may be positioned between the first transparent member 70 and the first diffuse-transmitting member 80. For example, the first half mirror 85 may be deposited on the surface of the first transparent member 70 on the opposite side of the detection position 15. The first half-mirror 85 is positioned such that its reflectivity to light traveling from the transport path 14 towards the first half-mirror 85 is greater than its reflectivity to light traveling from the first optical sensor 60 towards the first half-mirror 85. In other words, the light intensity of the light sources 30, 40, and 50 is adjusted so that the space where the transport path 14 is located is brighter than the space where the first optical sensor 60 is located. As a result, the first through-hole 83 is less likely to appear as a shadow in the image acquired by the second optical sensor 61. Therefore, a decrease in the identification accuracy of the identification unit 91 due to the first through-hole 83 can be suppressed.

[0051] Similarly, the second half-mirror 86 is positioned on the optical axis 61a of the second optical sensor 61 so as to cover the second through-hole 84 of the second diffuse-transmitting member 81. The second half-mirror 86 is located on the opposite side of the detection position 15 from the second diffuse-transmitting member 81 and is positioned perpendicular to the optical axis 61a of the second optical sensor 61. The second half-mirror 86 is positioned such that its reflectivity for light coming from the transport path 14 towards the second half-mirror 86 is greater than its reflectivity for light coming from the second optical sensor 61 towards the second half-mirror 86. As a result, the second through-hole 84 is less likely to appear as a shadow in the image acquired by the first optical sensor 60. Therefore, a decrease in the identification accuracy of the identification unit 91 due to the second through-hole 84 can be suppressed.

[0052] The first light source 30 on the front side includes a first upstream light source 31, first intermediate light sources 32, 33, and a first downstream light source 34. The first upstream light source 31 is positioned upstream to the region upstream of the detection position 15 on the transport path 14. The first downstream light source 34 is positioned downstream to the region downstream of the detection position 15 on the transport path 14. The first intermediate light sources 32, 33 are positioned intermediate to the detection position 15 and its vicinity. Here, the upstream position, downstream position, and intermediate position are relative positions along the direction in which the transport path 14 extends. The upstream position may be defined, for example, as the position corresponding to the upper quarter portion of the corresponding diffuse-transmitting member (i.e., the first diffuse-transmitting member 80) in the vertical direction. Similarly, the downstream position may be defined as the position corresponding to the lower quarter portion of the first diffuse-transmitting member 80 in the vertical direction. The intermediate position may be defined as the position between the upstream position and the downstream position.

[0053] Similarly, the rear-side second light source 40 includes a second upstream light source 41, second intermediate light sources 42, 43, and a second downstream light source 44. The second upstream light source 41 is positioned upstream to the region upstream of the detection position 15 on the transport path 14. The second downstream light source 44 is positioned downstream to the region downstream of the detection position 15 on the transport path 14. The second intermediate light sources 42, 43 are positioned intermediate to the detection position 15 and its vicinity. Here, the upstream position may be defined, for example, as the position corresponding to the upper quarter portion of the corresponding diffuse-transmitting member (i.e., the second diffuse-transmitting member 81) in the vertical direction. Similarly, the downstream position may be defined as the position corresponding to the lower quarter portion of the second diffuse-transmitting member 81 in the vertical direction. The intermediate position may be defined as the position between the upstream position and the downstream position.

[0054] The first intermediate light sources 32 and 33 are positioned so as to sandwich the detection position 15 in the direction in which the transport path 14 extends. In this embodiment, each of the first intermediate light sources 32 and 33 is oriented so that their optical axes 32a and 33a are perpendicular to the first diffuse-transmitting member 80. The distance between the first intermediate light source 32 and the first diffuse-transmitting member 80 is the same as the distance between the first intermediate light source 33 and the first diffuse-transmitting member 80. With this configuration, it is possible to avoid specular reflection of light from the first intermediate light sources 32 and 33 by the object 11 or the first transparent member 70. Therefore, it is possible to avoid excessive brightness in only certain directions, which would cause a portion of the image to become excessively white. Thus, it is possible to obtain an image that can be identified with higher accuracy.

[0055] Similarly, the second intermediate light sources 42 and 43 are positioned so as to sandwich the detection position 15 in the direction in which the transport path 14 extends. In this embodiment, each of the second intermediate light sources 42 and 43 is oriented such that their optical axes 42a and 43a are perpendicular to the second diffuse-transmitting member 81. The distance between the second intermediate light source 42 and the second diffuse-transmitting member 81 is the same as the distance between the second intermediate light source 43 and the second diffuse-transmitting member 81. This configuration provides the same effects as the first intermediate light sources 32 and 33. In an alternative embodiment, the first intermediate light sources 32 and 33 and the second intermediate light sources 42 and 43 may be oriented in any direction that allows light to be irradiated onto the object 11 at the detection position 15 via the diffuse-transmitting members 80 and 81. For example, the first intermediate light sources 32, 33 and the second intermediate light sources 42, 43 may be oriented so that their optical axes 32a, 33a, 42a, 43a pass through the detection position 15.

[0056] In this embodiment, the first upstream light source 31 is oriented so that its optical axis 31a is directed toward the detection position 15, and the first downstream light source 34 is oriented so that its optical axis 34a is directed toward the detection position 15. With this configuration, compared to the case where the optical axes 31a and 34a are oriented perpendicular to the first diffuse transmission member 80, it is possible to brighten the background 63 of the first optical sensor 60 while ensuring illumination that is less likely to produce shadows in the image. Therefore, the analog gain of the first optical sensor 60 can be reduced to obtain an image with less noise. Similarly, the second upstream light source 41 is oriented so that its optical axis 41a is directed toward the detection position 15, and the second downstream light source 44 is oriented so that its optical axis 44a is directed toward the detection position 15. Therefore, similarly, the analog gain of the second optical sensor 61 can be reduced to obtain an image with less noise. In an alternative embodiment, the light sources 31, 34, 41, and 44 may be oriented in any direction that allows light to be irradiated onto the object 11 at the detection position 15 via the diffuse-transmitting members 80 and 81. For example, the light sources 31, 34, 41, and 44 may be oriented such that their optical axes 31a, 34a, 41a, and 44a are perpendicular to the diffuse-transmitting members 80 and 81, respectively.

[0057] In this embodiment, the third light source 50 is oriented so that its optical axis 50a is perpendicular to the third diffuse transmission member 82 and directed toward the detection position 15. As a result, the object 11 is sufficiently illuminated from above, and the generation of shadows in the image is suppressed.

[0058] Since the light irradiated onto the object 11 from the first intermediate light source 32 is easily detected as transmitted light by the second optical sensor 61, the amount of charge of the light detected by the second optical sensor 61 is more greatly influenced by transmitted light than by reflected light. Taking this into consideration, in this embodiment, the light intensity of the first intermediate light sources 32 and 33 is set to be smaller than the light intensity of the first upstream light source 31 and the first downstream light source 34. This makes it possible to equalize the transmitted light and reflected light detected by the second optical sensor 61. Therefore, an image that can be identified with higher accuracy can be obtained. Similarly, the light intensity of the second intermediate light sources 42 and 43 is set to be smaller than the light intensity of the second upstream light source 41 and the second downstream light source 44.

[0059] In this embodiment, the distance between each of the first intermediate light sources 32 and 33 and the first diffuse-transmitting member 80 is greater than the distance between each of the first upstream light source 31 and the first downstream light source 34 and the first diffuse-transmitting member 80. Similarly, the distance between each of the second intermediate light sources 42 and 43 and the second diffuse-transmitting member 81 is greater than the distance between each of the second upstream light source 41 and the second downstream light source 44 and the second diffuse-transmitting member 81. Here, "distance" refers to the distance along the corresponding optical axis. This configuration also allows for balancing the transmitted and reflected light detected by each of the optical sensors 60 and 61, enabling the acquisition of images that can be identified with higher accuracy. In an alternative embodiment, the distance between each of the first intermediate light sources 32 and 33 and the first diffuse-transmitting member 80 may be the same as the distance between each of the first upstream light source 31 and the first downstream light source 34 and the first diffuse-transmitting member 80. Even in this case, a balance between transmitted light and reflected light can be achieved by setting the light intensity of the first intermediate light sources 32 and 33 to be less than that of the first upstream light source 31 and the first downstream light source 34. In a further alternative embodiment, the light intensity of the first intermediate light sources 32 and 33 may be set to be the same as that of the first upstream light source 31 and the first downstream light source 34. Even in this case, a balance between transmitted light and reflected light can be achieved by setting the distance between each of the first intermediate light sources 32 and 33 and the first diffuse-transmitting member 80 to be greater than the distance between each of the first upstream light source 31 and the first downstream light source 34 and the first diffuse-transmitting member 80. These alternative embodiments are also applicable to light sources 41 to 44.

[0060] According to the sorting device 10 described above, the light sources 30, 40, and 50 irradiate the object 11 with light via diffuse-transmitting members 80, 81, and 82, which are positioned across areas corresponding to the detection position 15, the area upstream of the detection position 15, and the area downstream of the detection position 15, respectively. As a result, the light that has passed through the diffuse-transmitting members 80, 81, and 82 and been diffused is irradiated onto the object 11 from various directions. Consequently, shadows are less likely to occur in the image of the object 11.

[0061] Furthermore, the diffuse-transmitting members 80, 81, and 82 have a flat surface on the side opposite to the detection position 15, that is, on the side where the light sources 30, 40, and 50 are located. This simplifies the direction of light diffusion compared to using a dome-shaped diffuse-transmitting member. As a result, it becomes easier to adjust the light intensity to suppress the generation of shadows in the image while ensuring sufficient illumination. For example, when the diffuse-transmitting member is dome-shaped, the light emitted from one light source spreads out overall, so it includes illumination from the same direction as other light sources. Therefore, when adjusting the brightness of each light source, it is necessary to fine-tune each light source while considering the overall balance of illumination. On the other hand, when the diffuse-transmitting member has a flat surface on the side opposite to the detection position 15, there is almost no illumination from the same direction between each light source. Therefore, it is sufficient to adjust only the illumination from a specific direction (i.e., the corresponding specific light source). Moreover, compared to using a dome-shaped diffuse-transmitting member, it becomes possible to place the light sources 30, 40, and 50 closer to the detection position 15. Therefore, although the diffusion-transmitting members 80, 81, and 82 have flat surfaces, meaning their diffusion performance is inferior to that of dome-shaped diffusion-transmitting members, sufficient illumination can still be ensured. Consequently, light intensity can be easily adjusted.

[0062] Furthermore, with the sorting device 10, light is irradiated onto the object 11 from both sides of the transport path 14 (i.e., the front and rear sides) via the first diffuse-transmitting member 80 and the second diffuse-transmitting member 81, which are positioned opposite each other with the transport path 14 in between, thus further reducing the likelihood of shadows appearing in the image. Moreover, with the sorting device 10, the first upstream light source 31, the first intermediate light sources 32, 33, and the first downstream light source 34 are positioned upstream, downstream, and intermediate positions along the direction in which the transport path 14 extends. As a result, light is irradiated onto the object from more directions. Consequently, shadows appear even less likely to appear in the image, and light intensity adjustment becomes easier. The same applies to the second upstream light source 41, the second intermediate light sources 42, 43, and the second downstream light source 44.

[0063] Furthermore, according to the sorting device 10, the intersection angle between the optical axis 60a of the first optical sensor 60 and the first diffuse-transmitting member 80 is the same as the intersection angle between the optical axis 61a of the second optical sensor 61 and the second diffuse-transmitting member 81, but the first diffuse-transmitting member 80 and the second diffuse-transmitting member 81 are arranged non-parallel to each other. For this reason, the second through-hole 84 of the second diffuse-transmitting member 81 is not located on the extension of the optical axis 60a of the first optical sensor 60, and the first through-hole 83 of the first diffuse-transmitting member 80 is not located on the extension of the optical axis 61a of the second optical sensor 61. Therefore, the first diffuse-transmitting member 80 and the second diffuse-transmitting member 81 can function as a background. The background is the background of the field of view of the optical sensor. Specifically, the portion of the second diffuse-transmitting member 81 that intersects with the extension of the optical axis 60a of the first optical sensor 60 functions as the background 63 for the first optical sensor 60, and the portion of the first diffuse-transmitting member 80 that intersects with the extension of the optical axis 61a of the second optical sensor 61 functions as the background 62 for the second optical sensor 61. With this configuration, there is no need to separately provide a background for each of the first optical sensor 60 and the second optical sensor 61, making the sorting device 10 more compact and reducing costs.

[0064] Furthermore, according to the sorting device 10, light is irradiated from the third light source 50 onto the object 11 located at the detection position 15 via a third diffuse-transmitting member 82, which is positioned to partially cover the gap between the upper edge 80a of the first diffuse-transmitting member 80 and the upper edge 81a of the second diffuse-transmitting member 81, and is angled to intersect the transport path 14 at a larger angle than the first diffuse-transmitting member 80 and the second diffuse-transmitting member 81. Therefore, in contrast to conventional technology, where a lack of light from above is common, the object 11 is sufficiently irradiated with light from above as well. Consequently, shadows are less likely to occur in the image, and light intensity adjustment becomes easier. Let θ1 be the angle formed in the upstream region by a straight line L1 connecting the first upstream light source 31 and the detection position 15, and by the transport path 14. Let θ2 be the angle formed in the upstream region by a straight line L2 connecting the third light source 50 and the detection position 15, and by the transport path 14. Then θ1 > θ2 is satisfied. When the optical axis 31a of the first upstream light source 31 is directed toward the detection position 15, the straight line L1 coincides with the optical axis 31a of the first upstream light source 31. When the optical axis 50a of the third light source 50 is directed toward the detection position 15, the straight line L2 coincides with the optical axis 50a of the third light source 50. In one embodiment, θ1 ≥ 45. In another embodiment, θ2 ≤ 35. In yet another embodiment, θ1 ≥ 45 and θ2 ≤ 35. According to these embodiments, it is easy to appropriately adjust the light from the side and / or from above so that no shadows are produced in the image.

[0065] Furthermore, the sorting device 10 does not require light-shielding plates or hood cylinder members as described in the aforementioned Japanese Patent Publication No. 6153311 and Japanese Patent Publication No. 6157086. Therefore, the device configuration can be simplified, and the light intensity can be easily adjusted.

[0066] The sorting device 110 according to the second embodiment will be described below with reference to Figures 2 and 3. In Figure 2, the same components as in the first embodiment (Figure 1) are denoted by the same reference numerals as in Figure 1. The sorting device 110 differs from the first embodiment in that it is equipped with third diffuse-transmitting members 182, 183 and third light sources 150, 151 instead of the third transparent member 72, third diffuse-transmitting member 82 and third light source 50, and it is equipped with a cleaning device 170. Below, only the differences between the sorting device 110 and the first embodiment will be described.

[0067] As shown in Figure 2, the third diffusion permeable members 182, 183 are positioned to partially cover the gap between the upper edge 80a of the first diffusion permeable member 80 and the upper edge 81a of the second diffusion permeable member 81, similar to the third diffusion permeable member 82 of the first embodiment, and are angled to intersect the transport path 14 at a larger angle than the first diffusion permeable member 80 and the second diffusion permeable member 81. The third diffusion permeable members 182, 183 are supported by support members (not shown) outside the belt conveyor 23 in the width direction of the belt conveyor 23.

[0068] The third diffuse-transmitting members 182 and 183 are spaced apart in the direction away from the detection position 15. In this embodiment, the third diffuse-transmitting members 182 and 183 are parallel to each other. Furthermore, the third diffuse-transmitting members 182 and 183 are arranged so as to partially overlap each other when viewed in a direction perpendicular to each other. The third diffuse-transmitting member 182 is positioned between the third light source 150 and the detection position 15, and the third diffuse-transmitting member 183 is positioned between the third light source 151 and the detection position 15.

[0069] The third light source 150 irradiates the object 11 at the detection position 15 with light via the third diffuse-transmitting member 182. The third light source 151 irradiates the object 11 at the detection position 15 with light via the third diffuse-transmitting member 183. A portion of the light from the third light source 151 may be irradiated onto the object 11 at the detection position 15 via the third diffuse-transmitting members 182 and 183. The third light sources 150 and 151 are light source units for irradiating visible light, similar to the third light source 50. With this configuration, as in the first embodiment, shadows are less likely to occur in the image of the object 11, and the light intensity can be easily adjusted.

[0070] As shown in Figure 3, the sorting device 110 includes a cleaning device 170 for cleaning the first transparent member 70 and the second transparent member 71. In this embodiment, the cleaning device 170 is in the form of a wiper. The cleaning device 170 comprises a support portion 171 and wiper portions 172 and 173. The support portion 171 passes through the gap between the third diffusion permeable member 182 and the third diffusion permeable member 183 and extends into the space between the first transparent member 70 and the second transparent member 71. One end of the support portion 171 is operably connected to an actuator (not shown) configured to slide the cleaning device 170 in the width direction of the belt conveyor 23.

[0071] The other end of the support portion 171 branches into two directions: one toward the first transparent member 70 and the other toward the second transparent member 71. Wiper portions 172 and 173 are connected to the tips of these two branched portions, respectively. Wiper portion 172 is positioned parallel to the first transparent member 70, and wiper portion 173 is positioned parallel to the second transparent member 71.

[0072] The cleaning device 170 is movable between a retracted position (not shown) where it is moved outward in the width direction of the belt conveyor 23 from the transport path 14 by the actuator described above, and a cleaning position (Figure 3) where the wiper parts 172 and 173 are positioned between the first transparent member 70 and the second transparent member 71. When not in use, the cleaning device 170 is retracted to the retracted position. When in use, the cleaning device 170 moves in the width direction of the belt conveyor 23 with the wiper part 172 in contact with the first transparent member 70 and the wiper part 173 in contact with the second transparent member 71 in the cleaning position, thereby cleaning dust adhering to the inner surfaces of the first transparent member 70 and the second transparent member 71.

[0073] In an alternative embodiment, the cleaning device 170 may include a wiper portion that can contact the inner surfaces of the third diffusion permeable members 182, 183. In a further alternative embodiment, the cleaning device 170 may include, in place of or in addition to, the wiper portions 172, 173, a spraying device that sprays air or cleaning water toward the inner surfaces of the first transparent member 70 and the second transparent member 71.

[0074] The sorting device 210 according to the third embodiment will be described below with reference to Figure 4. In Figure 4, components identical to those in the first embodiment (Figure 1) or the second embodiment (Figure 2) are denoted by the same reference numerals as in Figure 1 or Figure 2. Hereafter, only the differences between the sorting device 210 and the second embodiment will be described.

[0075] The first upstream light source 31 and the first downstream light source 34 are oriented so that their optical axes 31a and 34a are perpendicular to the first diffuse-transmitting member 80. In addition, the sorting device 210 is equipped with a second light source 240 instead of the second light source 40. The second light source 240 is positioned only at a location corresponding to the position of the second downstream light source 44 in the first embodiment. In this embodiment, the second light source 240 is oriented so that its optical axis 240a is perpendicular to the second diffuse-transmitting member 81. By oriented the light sources 31, 34, and 240 in this way, the upstream and downstream regions of the detection position 15 can be made brighter.

[0076] The sorting device 210 does not have a second optical sensor 61. Consequently, the sorting device 210 does not have a first half mirror 85 and a second half mirror 86, and the second diffusion transmission member 81 does not have a second through hole 84.

[0077] The sorting device 210 is equipped with a partition plate 287. In this embodiment, the partition plate 287 is a milky white plate and is positioned above and near the second light source 240 so as to be in contact with the second diffuser / transmitting member 81. By providing the partition plate 287, it becomes more difficult for light from the second light source 240 to irradiate the background 63. As a result, the background 63 is prevented from becoming excessively bright compared to the area near the second light source 240, and the generation of shadows caused by this is suppressed. In addition, the illuminance at the detection position 15 can be increased by the reflective effect of the partition plate 287 on the light emitted from the second light source 240.

[0078] The sorting device 210 described above can also adjust the light intensity to prevent shadows from appearing in the image, depending on the properties and shape of the object 11. Furthermore, the sorting device 210 allows for a simpler device configuration compared to the first or second embodiment. The sorting device 210 is particularly suitable, for example, when the object 11 is a transparent granular material (e.g., transparent resin pellets).

[0079] The sorting device 310 according to the fourth embodiment will be described below with reference to Figure 5. Figure 5 shows a part of the configuration of the front side of the sorting device 310. Also, in Figure 5, the same components as in the first embodiment (Figure 1) are denoted by the same reference numerals as in Figure 1. Below, only the differences between the sorting device 310 and the first embodiment will be described. On the front side of the sorting device 310, instead of the first half mirror 85, a mirror 381, a first auxiliary diffuse transmitting member 382, ​​and a first half mirror 383 are provided. The mirror 381, the first auxiliary diffuse transmitting member 382, ​​and the first half mirror 383 are arranged between the first intermediate light sources 32, 33 and the first diffuse transmitting member 80 in the direction in which the optical axis 60a of the first optical sensor 60 extends.

[0080] The first half-mirror 383 is positioned on the optical axis 60a of the first optical sensor 60, which passes through the first through-hole 83. The first half-mirror 383 is positioned such that its reflectivity for light traveling from the transport path 14 towards the first half-mirror 383 is greater than its reflectivity for light traveling from the first optical sensor 60 towards the first half-mirror 383. The first optical sensor 60 acquires an image of the object 11 at the detection position 15 via the first half-mirror 383. In this embodiment, the mirror 381 is a total reflection mirror. The first auxiliary diffuse-transmitting member 382 is positioned between the mirror 381 and the first half-mirror 383. The first auxiliary diffuse-transmitting member 382 has a flat surface on the side closer to the mirror 381.

[0081] A portion of the light emitted from the first intermediate light source 33 is reflected by the mirror 381, as shown by the optical axis 33b, then diffused through the first auxiliary diffuser 382, ​​and finally reflected by the first half-mirror 383, passing through the first through-hole 83 to the detection position 15. With this configuration, additional light is guided to the first through-hole 83, which does not have a diffusing element (i.e., tends to be darker than other areas), so the first through-hole 83 can be effectively suppressed from appearing as a shadow in the image acquired by the second optical sensor 61. Although a similar effect can be obtained with the first half-mirror 85 according to the first embodiment, the first half-mirror 85 spectrally separates the light coming from the detection position 15 side toward the first half-mirror 85 into reflected light and transmitted light. For this reason, according to this embodiment, the first through-hole 83 can be suppressed as a shadow more effectively than in the first embodiment. Furthermore, since no additional light source is required to obtain such an effect, the sorting device 10 can be made more compact and its cost can be reduced.

[0082] Although not shown in the diagram, the sorting device 310 has the same configuration on the rear side as on the front side. Therefore, the shadow of the second through-hole 84 in the image acquired by the first optical sensor 60 can be effectively suppressed. In an alternative embodiment, the mirror 381 may be a half-mirror. In this case, the presence of the mirror 381 can suppress insufficient light illuminating the object 11 at the detection position 15 from the first intermediate light source 33. Alternatively, it is easier to make adjustments so that no light deficiency occurs.

[0083] The sorting device 410 according to the fifth embodiment will be described below with reference to Figure 6. Figure 6 shows a part of the front side configuration of the sorting device 410. Also, in Figure 6, the same components as in the first embodiment (Figure 1) are denoted by the same reference numerals as in Figure 1. Below, only the differences between the sorting device 410 and the first embodiment will be described. On the front side of the sorting device 410, instead of the first half mirror 85, a first auxiliary diffusion transmission member 482 and a first half mirror 483 are provided. The sorting device 410 further includes a first auxiliary light source 430.

[0084] The first auxiliary light source 430, the first auxiliary diffuse transmitting member 482, and the first half mirror 483 are positioned between the first optical sensor 60 and the first light source 30 in the direction in which the optical axis 60a of the first optical sensor 60 extends. The first auxiliary diffuse transmitting member 482 has a flat surface on the side facing the first auxiliary light source 430. The first half mirror 483 is positioned on the optical axis 60a of the first optical sensor 60 passing through the first through hole 83. The first half mirror 483 is positioned such that its reflectivity for light traveling from the transport path 14 towards the first half mirror 483 is greater than its reflectivity for light traveling from the first optical sensor 60 towards the first half mirror 483. The first optical sensor 60 acquires an image of the object 11 at the detection position 15 via the first half mirror 483.

[0085] Light emitted from the first auxiliary light source 430 is diffused by passing through the first auxiliary diffuser / transmitter member 482, as shown by the optical axis 430a, then reflected by the first half-mirror 483, and reaches the detection position 15 through the first through-hole 83. With this configuration, as in the fourth embodiment, additional light is guided to the first through-hole 83, which does not have a diffuser element, so the first through-hole 83 can be effectively suppressed from appearing as a shadow in the image acquired by the second optical sensor 61. Moreover, since a mirror 381 is not required as in the fourth embodiment, the light irradiated from the first light source 30 onto the object 11 at the detection position 15 is not obstructed. Therefore, light intensity adjustment is easy. Furthermore, since the first auxiliary light source 430 is provided separately from the first light source 30, light intensity adjustment to reduce shadows on the object 11 and light intensity adjustment to reduce shadows caused by the first through-hole 83 can be performed independently. Therefore, light intensity adjustment becomes even easier.

[0086] Although not shown in the diagram, the sorting device 410 has the same configuration on the rear side as on the front side. Therefore, the second through-hole 84 can be effectively suppressed from appearing as a shadow in the image acquired by the first optical sensor 60.

[0087] The measuring device 510 according to the sixth embodiment will be described below with reference to Figure 7. In Figure 7, the same components as in the first embodiment (Figure 1) are denoted by the same reference numerals as in Figure 1. Hereinafter, only the differences between the measuring device 510 and the first embodiment will be described. The measuring device 510 optically measures the state of the object 11. The measuring device 510 differs from the first embodiment in that it does not have a sorting unit 26 and has a discharge trough 524 instead of a good product discharge trough 24 and a defective product discharge trough 25. The object 11 on the transport path 14 is optically detected at the detection position 15 and then discharged into the discharge trough 524. The controller 90 outputs the identification result from the identification unit 91 to any device. Such a device may be a storage device, a printing device, a display device, a communication device, etc. Although not shown, the configurations of the second to fifth embodiments can also be applied to the measuring device 510.

[0088] Although several embodiments have been described above, these embodiments are intended to facilitate understanding of the present invention and do not limit it. The present invention can be modified and improved without departing from its spirit, and its equivalents are included. Furthermore, any combination or omission of the components described in the claims and specification is possible to the extent that at least some of the above-mentioned problems can be solved or at least some of the effects can be achieved.

[0089] For example, in the first embodiment, the third diffuse transmission member 82 may be located on the rear side. In this case, the third light source 50 may also be located on the rear side. Alternatively, the third diffuse transmission member 82 may comprise two members, one located on the front side and the other on the rear side, with the transport path 14 in between. In this case, the third light source 50 may comprise a front-side light source and a rear-side light source.

[0090] Furthermore, the specifications of the light sources (number, arrangement, orientation, light intensity, etc.) and the number, arrangement, and orientation of the diffuse-transmitting members can be arbitrarily changed, as long as at least one diffuse-transmitting member is arranged between at least one light source and the detection position 15, spanning areas corresponding to the detection position 15, the upstream area, and the downstream area, respectively. The specifications of the light sources and the number, arrangement, and orientation of the diffuse-transmitting members can be appropriately changed according to the characteristics of the object 11 (properties, shape, etc.), the required identification accuracy, the device specifications, etc. For example, with respect to the first embodiment, one first intermediate light source may be used on the front side instead of the first intermediate light sources 32, 33. Alternatively, on the front side, the first intermediate light sources 32, 33 may be omitted, the third light source 50 may be omitted, or the first upstream light source 31 may be omitted. These points are also true on the rear side. Alternatively, the sorting device 10 may be equipped only with the first upstream light source 31, the first downstream light source 34, and the second downstream light source 44. Alternatively, the light source may be located on only one of the front or rear sides. Alternatively, the first diffuse-transmitting member 80 and the second diffuse-transmitting member 81 may be arranged parallel to each other. In addition to or instead of this configuration, the detection position of the first optical sensor 60 on the transport path 14 and the detection position of the second optical sensor 61 on the transport path 14 may be different. In this case, the controller 90 may perform a trajectory change operation based on the detection result of the first optical sensor 60 and a trajectory change operation based on the detection result of the second optical sensor 61 in parallel. In a configuration where the first diffusion-transmitting member 80 and the second diffusion-transmitting member 81 are arranged parallel to each other, and the detection position of the first optical sensor 60 and the detection position of the second optical sensor 61 are different, if the first optical sensor 60 and the second optical sensor 61 are oriented such that the second through-hole 84 is located outside the field of view of the first optical sensor 60 and the first through-hole 83 is located outside the field of view of the second optical sensor 61, the generation of shadows caused by the first through-hole 83 and the second through-hole 84 can be prevented without providing the first half-mirror 85 and the second half-mirror 86.Alternatively, the measuring or sorting device may be provided with only one of the light sources 31-34 or only one of the light sources 41-44, as an unrestricted example of the “light source” in the claims, and may be provided with only the first diffuse-transmitting member 80 or only the second diffuse-transmitting member 81, as an unrestricted example of the “diffuse-transmitting member disposed between the light source and the detection position over areas corresponding to the detection position, the area upstream of the detection position, and the area downstream of the detection position on the transport path.” Furthermore, reflectors and partitions may be used as appropriate depending on the specifications of the light source.

[0091] Furthermore, instead of a configuration in which light is shone onto the object 11 after it has fallen from the belt conveyor 23 and the light associated with the object 11 is detected by optical sensors 60 and 61, a configuration may be adopted in which light is shone onto the object 11 while it is being transported on the belt conveyor 23 and the light associated with the object 11 is detected. Alternatively, a chute may be used instead of the belt conveyor 23 as the transport means. In this case, a configuration may be adopted in which light is shone onto the object 11 after it has fallen from the chute and the light associated with the object 11 is detected, or a configuration may be adopted in which light is shone onto the object 11 while it is sliding along the chute and the light associated with the object 11 is detected.

[0092] The various embodiments described above are particularly effective when dealing with granular objects that are prone to casting shadows in images. For example, transparent resin pellets are very prone to casting shadows if light cannot be irradiated uniformly in all directions, so the above embodiments are very effective. Also, when dealing with granular objects with asymmetrical shapes (e.g., elliptical cylinders), shadows are likely to occur depending on the orientation of the object at the detection position, requiring stringent optical conditions, so the above embodiments are very effective. However, the objects are not limited to the granular objects exemplified in this specification. [Explanation of Symbols]

[0093] 10... Optical sorting device 11, 12, 13... Objects 14...Transportation route 15...Detection location 21...Storage tank 22...feeder 23... Belt conveyor 24...Good product discharge trough 25...Defective product discharge trough 26... Sorting Department 27... Spray nozzle 28...valve 29...Air 30...First light source 31...First upstream light source 32,33...First intermediate light source 34...First downstream light source 31a,32a,33a,33b,34a...optical axis 40...Second light source 41...Second upstream light source 42, 43... Second intermediate light source 44...Second downstream light source 41a, 42a, 43a, 44a... Optical axis 50... Third light source 50a...Optical axis 60...First optical sensor 61...Second optical sensor 60a, 61a... Optical axis 62, 63... background 70...First transparent component 71...Second transparent component 72...Third transparent component 80...First diffusion and permeation member 80a...upper edge 81...Second diffusion and permeation member 81a...Upper edge 82...Third diffusion and permeation member 83...First through hole 84...Second through hole 85...First half mirror 86...Second half mirror 90... Controller 91...Identification section 110... Sorting device 150, 151... Third light source 170...Cleaning equipment 171...Support part 172, 173... Wiper section 182,183...Third diffusion and permeation member 210... Sorting device 240...Second light source 240a...Optical axis 287...Partition plate 310... Sorting device 381...Mirror 382...First auxiliary diffusion and permeation member 383...First half mirror 410... Sorting device 430...First auxiliary light source 430a...Optical axis 482...First auxiliary diffusion and permeation member 483...First half mirror 510... Measuring device 524...Drainpipe

Claims

1. A measuring device for measuring the state of granular objects, A light source configured to irradiate the object being transported along a transport path with light, An optical sensor configured to detect light irradiated from the light source and associated with the object located at a detection position on the transport path, An identification unit configured to identify the state of the object based on a signal acquired by the optical sensor with respect to light associated with the object, A diffuse permeable member is disposed between the light source and the detection position, extending over regions corresponding to the detection position, the region upstream of the detection position, and the region downstream of the detection position on the transport path, wherein the diffuse permeable member has a flat surface on the side opposite to the detection position. A measuring device equipped with the following features.

2. A measuring device according to claim 1, The light source includes a first light source located at a first position relative to the detection position, and a second light source located at a second position different from the first position relative to the detection position. The diffuse transmission member includes a first diffuse transmission member disposed between the first light source and the detection position, and a second diffuse transmission member disposed between the second light source and the detection position. Measuring device.

3. A measuring device according to claim 2, The aforementioned light source includes a third light source, The diffusion-transmitting member is positioned between the third light source and the detection position so as to partially cover the gap between the upper edge of the first diffusion-transmitting member and the upper edge of the second diffusion-transmitting member, and includes a third diffusion-transmitting member angled to intersect the transport path at a larger angle than the first diffusion-transmitting member and the second diffusion-transmitting member. Measuring device.

4. A measuring device according to claim 2 or claim 3, The first position is located on one side of the transport path, The second position is located on the opposite side from the one side with respect to the transport path, The first diffusion permeable member and the second diffusion permeable member are arranged to face each other with the transfer path in between, The optical sensor includes a first optical sensor located at the first position and a second optical sensor located at the second position. The first diffusion-permeating member and the second diffusion-permeating member are arranged non-parallel to each other. The first diffusion-transmitting member has a first through-hole in a region corresponding to the field of view of the first optical sensor, The second diffusion-transmitting member has a second through-hole in a region corresponding to the field of view of the second optical sensor. The measuring device is, A first half-mirror covering the first through hole, A second half-mirror covering the second through hole and A measuring device equipped with the following features.

5. A measuring device according to claim 2 or claim 3, The first position is located on one side of the transport path, The second position is located on the opposite side from the one side with respect to the transport path, The first diffusion permeable member and the second diffusion permeable member are arranged to face each other with the transfer path in between, The optical sensor includes a first optical sensor located at the first position and a second optical sensor located at the second position. The first diffusion-permeating member and the second diffusion-permeating member are arranged non-parallel to each other. The first diffusion-transmitting member has a first through-hole in a region corresponding to the field of view of the first optical sensor, The second diffusion-transmitting member has a second through-hole in a region corresponding to the field of view of the second optical sensor. The measuring device is, A first half-mirror positioned on the optical axis of the first optical sensor passing through the first through-hole, A second half-mirror positioned on the optical axis of the second optical sensor passing through the second through-hole, A first auxiliary diffusion and permeation member, A second auxiliary diffusion and permeation member, Equipped with, The device is configured such that light that passes through the first auxiliary diffuse-transmitting member and is reflected by the first half-mirror passes through the first through-hole, and light that passes through the second auxiliary diffuse-transmitting member and is reflected by the second half-mirror passes through the second through-hole. Measuring device.

6. A sorting device, A measuring device according to any one of claims 1 to 3, A sorting unit configured to sort the objects based on the identification result of the identification unit, A sorting device equipped with the following features.

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