Identification device, classification device, identification method, classification method, and article manufacturing method

Abstract

To provide a technique advantageous for accurately identifying the type of a plastic piece.SOLUTION: An identification device identifies the type of a plastic piece conveyed on a conveyance path, and comprises: a measurement unit that, while the plastic piece passes through a predetermined area on the conveyance path, irradiates the plastic piece with an infrared ray and measures reflected light from the plastic piece, in each of a plurality of conditions different from each other; and a processing unit that specifies the type of the plastic piece on the basis of the reflected light in a condition, of the plurality of conditions, in which the quantity of the reflected light measured by the measurement unit is within a prescribed range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an identification device, a classification device, an identification method, a classification method, and an article manufacturing method. [Background technology]

[0002] Traditionally, industrial waste such as automobiles and home appliances has been separated into metals such as iron and aluminum and plastics containing various materials in various recycling processes. In recent years, attempts have been made to reuse these plastics as materials for plastic molded parts through horizontal recycling, and systems have been developed to identify and classify specific types (materials) of plastic from plastics containing various materials.

[0003] For example, Patent Document 1 discloses a technology for identifying the type of waste plastic pieces by irradiating the pieces with infrared light and then dispersing the reflected light. In this technology, infrared light is irradiated onto the waste plastic pieces flowing on a belt conveyor, and the reflected light from the pieces is dispersed to detect a spectral waveform. The detected spectral waveform is then compared with spectral waveforms registered in advance for each material to identify the material of the waste plastic. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5367145 Summary of the Invention [Problem to be solved by the invention]

[0005] The various plastic pieces transported on the belt conveyor have different infrared reflection characteristics due to variations in surface texture, which can make it difficult to accurately identify the type of plastic piece. Specifically, the various plastic pieces include those with highly glossy surfaces (glossy surfaces) and those with less glossy surfaces (rough surfaces). Because the reflectivity of infrared light differs greatly between glossy and rough surfaces, there is a large difference in the intensity of the reflected light, which can make it difficult for a sensor to accurately detect the reflected light.

[0006] Therefore, an object of the present invention is to provide an advantageous technique for accurately identifying the type of plastic piece. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, one aspect of the present invention is an identification device that identifies the type of plastic piece being transported on a transport path, and is characterized by comprising: a measurement unit that irradiates the plastic piece with infrared light and measures the reflected light from the plastic piece under each of a plurality of different conditions while the plastic piece passes through a specified area on the transport path; and a processing unit that identifies the type of the plastic piece based on the reflected light under a condition among the plurality of conditions in which the amount of reflected light measured by the measurement unit is within a specified range.

[0008] Further objects and other aspects of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. [Effects of the Invention]

[0009] According to the present invention, for example, it is possible to provide an advantageous technique for accurately identifying the type of plastic piece. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a classification device according to an embodiment. [Figure 2]A diagram showing an example of the configuration and operation of a measurement unit. [Figure 3] 1 is a diagram showing an example of the configuration and operation of a light detection unit; [Figure 4] FIG. 1 is a diagram for explaining the identification process of the first embodiment. [Figure 5] FIG. 10 shows examples of spectral waveforms obtained under each of the measurement conditions C11 to C13. [Figure 6] FIG. 10 is a diagram for explaining the identification process of the second embodiment. [Figure 7] FIG. 10 is a diagram for explaining the identification process of the third embodiment. [Figure 8] 1 is a flowchart showing a method for controlling a cycle of measuring reflected light. [Figure 9] Flowchart showing a method for controlling the conveying speed of waste plastic pieces DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] First Embodiment A first embodiment of a sorting device 100 (sorting system) according to the present invention will be described. The sorting device 100 is a system that identifies the type of each of a plurality of plastic pieces transported on a transport path and sorts the plurality of plastic pieces by type based on the identification results. Examples of plastic piece types include the material (raw material) and / or size of the plastic pieces. In this embodiment, a belt conveyor is used as a transport mechanism for transporting the plastic pieces, and an example in which the transport path of the plastic pieces is defined by the upper surface of the belt conveyor will be described. However, the transport mechanism is not limited to a belt conveyor, as long as it can transport the plastic pieces, such as a hand that holds and transports the plastic pieces. Similarly, the transport path is not limited to the upper surface of a belt conveyor, as long as it is a path along which the plastic pieces are transported, such as a path along which the plastic pieces are transported by a hand. In the following description, discarded and crushed plastic pieces (sometimes referred to as waste plastic pieces) will be used as an example of the plastic pieces transported on the transport mechanism.

[0013] [Configuration of classification device] 1 is a diagram showing an example of the configuration of a sorting device 100 of this embodiment. The sorting device 100 of this embodiment may include a belt conveyor 10, a detection unit 20, a measurement unit 30, a processing unit 40, a sorting unit 50, and a drive unit 60. In the following description, directions are indicated in an XYZ coordinate system in which the upper surface 11 of the belt conveyor 10 is the XY plane, and the direction in which the waste plastic pieces WP are transported by the belt conveyor 10 is defined as the Y direction.

[0014] The waste plastic pieces WP are, for example, thermoplastic or thermosetting plastics crushed to a size of about 10 to 100 mm. In the sorting device 100 of this embodiment, a plurality of waste plastic pieces WP are fed onto the belt conveyor 10 via a fixed amount feeder or a vibration feeder (not shown).

[0015] The belt conveyor 10 is a transport mechanism that transports multiple waste plastic pieces WP, and its upper surface 11 defines the transport path for the multiple waste plastic pieces WP. The belt conveyor 10 moves a belt made of rubber, resin, or metal at a predetermined speed, and the size and moving speed of the belt can be set according to the processing capacity of the sorting device 100. In the example of Figure 1, the belt conveyor 10 is configured to transport multiple waste plastic pieces WP in the direction of arrow A (Y direction).

[0016] The detection unit 20 (recognition unit) detects the position of each of the multiple waste plastic pieces WP on the conveying path (i.e., the position on the upper surface 11 of the belt conveyor 10). For example, the detection unit 20 has an imaging unit 21 whose imaging field of view 20' includes a portion of the conveying path, and an illumination unit 22 that illuminates the waste plastic pieces WP within the imaging field of view 20'. The imaging unit 21 includes a CCD camera or the like, and the imaging field of view 20' can be set to a shape that extends in the width direction (X direction) of the belt conveyor 10. Furthermore, the imaging unit 21 captures images at a cycle corresponding to the belt movement speed of the belt conveyor 10 so that each of the multiple waste plastic pieces WP conveyed by the belt conveyor 10 can be imaged within the imaging field of view 20'. This allows the detection unit 20 to detect the position (e.g., position in the X direction and / or Y direction) of each waste plastic piece WP on the belt conveyor 10 based on the image obtained by the imaging unit 21. The detection unit 20 may be configured to detect the size of each waste plastic piece WP based on the image obtained by the imaging unit 21.

[0017] Here, the detection unit 20 of this embodiment may include, but is not limited to, a processor that performs detection processing to detect the position and size of the waste plastic pieces WP based on the image obtained by the imaging unit 21. For example, the image obtained by the imaging unit 21 may be supplied to the processing unit 40, and the processing unit 40 may perform the detection processing. In other words, in this case, the processing unit 40, the imaging unit 21, and the illumination unit 22 may be understood to constitute a detection unit that performs the detection processing.

[0018] The measuring unit 30 irradiates the waste plastic pieces WP being transported by the belt conveyor 10 with infrared light (infrared rays) and measures the light reflected from the waste plastic pieces WP. The measuring unit 30 has, for example, a light irradiating unit 31 that irradiates the waste plastic pieces WP with infrared light, and a light detecting unit 32 that detects the light reflected from the waste plastic pieces WP irradiated with infrared light by the light irradiating unit 31. The area 31' surrounded by a dashed dotted line in FIG. 1 is the area on the transport path (upper surface 11 of the belt conveyor 10) that is irradiated with infrared light by the light irradiating unit 31, and may be referred to as the "irradiated area 31'" below. The irradiated area 31' can be set to a shape that extends in the width direction (X direction) of the belt conveyor 10. A specific configuration example of the measuring unit 30 will be described later.

[0019] The processing unit 40 is a computing device such as a computer or a sequencer. The processing unit 40 of this embodiment may be configured as an information processing device having a processor such as a CPU (Central Processing Unit) and a storage unit such as a memory. The processing unit 40 identifies the type of each of the multiple waste plastic pieces WP transported by the belt conveyor 10 based on the reflected light measured by the measuring unit 30. The processing unit 40 also functions as a control unit that controls a classification process that classifies the multiple waste plastic pieces WP by type based on the identification results. The processing unit 40 may have a user interface 41 (input unit) for a user to input various information. Hereinafter, the measuring unit 30 and the processing unit 40 constitute an identification device that identifies the type of waste plastic pieces WP transported by the belt conveyor 10. Hereinafter, the measuring unit 30 and the processing unit 40 may be collectively referred to as the "identification device."

[0020] The sorting unit 50 (sorting mechanism) is disposed near the end of the belt conveyor 10 and sorts each of the multiple waste plastic pieces WP transported by the belt conveyor 10 by type. The sorting unit 50 of this embodiment has multiple openings 51 (air nozzles) arranged in the width direction of the belt conveyor 10 and is configured to release compressed air from each opening 51 at an independent timing. The sorting unit 50 then releases compressed air toward the waste plastic pieces WP from at least one of the multiple openings 51 depending on the position and timing at which the waste plastic pieces WP are transported by the belt conveyor 10. As a result, the waste plastic pieces WP are stored (thrown into) one of the multiple storage boxes 71-72.

[0021] Here, the sorting unit 50 can be driven by the drive unit 60 under the control of the processing unit 40. Specifically, the processing unit 40 acquires the detection results of the detection unit 20 and the identification results of the identification device for the waste plastic pieces WP transported by the belt conveyor 10. The detection results of the detection unit 20 are the results of detection by the detection unit 20 of the position of the waste plastic pieces WP on the belt conveyor 10. The identification results of the identification device are the results of identifying the type of the waste plastic pieces WP based on the measurement results of the reflected light by the measurement unit 30. Then, the processing unit 40 generates a drive signal for driving the sorting unit 50 based on the acquired detection results and identification results and supplies the drive signal to the drive unit 60. The drive signal can include information indicating the target opening 51 to be used for the waste plastic pieces WP and the timing of releasing compressed air from the target opening 51.

[0022] The driving unit 60 is a pneumatic device equipped with a plurality of solenoid valves for controlling the release of compressed air from each of the plurality of openings 51 in the sorting unit 50. Based on a drive signal supplied from the processing unit 40, the driving unit 60 sends compressed air to the target opening 51 by opening the solenoid valve corresponding to the target opening 51 among the plurality of solenoid valves at the release timing.

[0023] The multiple storage boxes 71-72 are containers that store the waste plastic pieces WP by type, and can be arranged along the conveying direction (X direction) of the waste plastic pieces WP. In the example of Fig. 1, two storage boxes 71-72 are illustrated, but a storage box is prepared for each type into which the waste plastic pieces WP should be sorted. In other words, three or more storage boxes may be provided.

[0024] [Sorting of waste plastic pieces] Next, the process of sorting the waste plastic pieces WP in the sorting device 100 of this embodiment will be explained step by step with reference to FIG.

[0025] Waste plastic pieces WP fed onto the belt conveyor 10 by a fixed quantity dispensing device, a vibrating feeder, or the like (not shown) are transported on the belt conveyor 10 in the direction of arrow A. The detection unit 20 captures an image of the waste plastic piece WP using the imaging unit 21 while the waste plastic piece WP passes through the imaging field of view 20'. Then, based on the image obtained by the imaging unit 21, the detection unit 20 determines (calculates) the position and size of the waste plastic piece WP on the belt conveyor 10.

[0026] Furthermore, while the waste plastic pieces WP are passing through the irradiation area 31', infrared light is irradiated from the measurement unit 30. After being reflected by the surface of the waste plastic pieces WP, the infrared light enters the measurement unit 30 as reflected light. The measurement unit 30 has a spectrometer that disperses the reflected light, and generates a wavelength distribution image that visualizes the wavelength distribution of the reflected light using the spectrometer, and supplies the generated image to the processing unit 40. The processing unit 40 performs predetermined calculation processing on the wavelength distribution image supplied from the measurement unit 30, thereby converting the wavelength distribution image into a spectral waveform that indicates the light intensity for each wavelength.

[0027] The storage unit (memory) of the processing unit 40 stores a spectral waveform (hereinafter referred to as a reference spectral waveform) that should be obtained by the measurement unit 30 for each type of waste plastic piece WP. The processing unit 40 collates (compares) the spectral waveform obtained by the measurement unit 30 with each type of reference spectral waveform to calculate a correlation value (e.g., degree of agreement). This allows the processing unit 40 to identify (determine) the type of reference spectral waveform whose correlation value is equal to or greater than a predetermined value (e.g., the type of reference spectral waveform whose correlation value is highest) as the type of waste plastic piece WP whose reflected light was measured by the measurement unit 30.

[0028] The processing unit 40 determines a storage box in which to store the waste plastic piece WP based on the result of identifying the type of the waste plastic piece WP, and calculates the timing of passing over the sorting unit 50 and the position in the X direction on the belt conveyor 10 based on the detection result of the detection unit 20. As a result, the processing unit 40 can generate a drive signal that specifies the target opening 51 to be used to classify the waste plastic piece WP from among the multiple openings 51 in the sorting unit 50 and the timing of releasing compressed air from the target opening 51, and supply the drive signal to the drive unit 60. Based on the drive signal, the drive unit 60 opens the solenoid valve corresponding to the target opening 51 at the release timing, thereby sending compressed air to the target opening 51. The waste plastic piece WP hit by the compressed air released from the target opening 51 has its trajectory changed, and is stored in one of the multiple storage boxes 71-72 that is farthest from the sorting unit 50. On the other hand, for waste plastic pieces WP that are determined to be stored in the storage box 72 that is closer to the sorting unit 50 among the multiple storage boxes 71-72, no drive signal is supplied to the drive unit 60, or a drive signal that specifies that compressed air will not be released is supplied to the drive unit 60. In this case, the waste plastic pieces WP are stored in the storage box 72 without the sorting unit 50 changing their trajectory.

[0029] Here, to calculate the timing at which the waste plastic pieces WP pass over the sorting unit 50, in addition to position information indicating the position of the waste plastic pieces WP on the belt conveyor 10, speed information indicating the transport speed of the waste plastic pieces WP by the belt conveyor 10 is required. The processing unit 40 may acquire the speed information based on the result of detecting the rotation speed of the motor driving the belt conveyor 10 using an encoder or the like, or may acquire the speed information based on the result of directly detecting the belt speed of the belt conveyor 10 using a speed sensor or the like. However, this is not limited thereto, and for example, the processing unit 40 may acquire the speed information based on the cycle at which reference marks periodically formed on the belt of the belt conveyor 10 are detected (imaged) by the detection unit 20 (image capturing unit 21).

[0030] By the above process, when the waste plastic pieces WP transported by the belt conveyor 10 pass over the sorting section 50, the release of compressed air onto the waste plastic pieces WP from each opening 51 of the sorting section 50 is controlled. As a result, the waste plastic pieces WP that have been hit with compressed air are stored in the storage box 71 that is farther from the sorting section 50, and the waste plastic pieces WP that have not been hit with compressed air are stored in the storage box 72 that is closer to the sorting section 50. In other words, according to the sorting device 100 of this embodiment, multiple waste plastic pieces WP transported by the belt conveyor 10 can be sorted by type.

[0031] [Configuration of measurement section] Next, a description will be given of an example of the configuration and operation of the measurement unit 30. Fig. 2 is a diagram showing an example of the configuration and operation of the measurement unit 30. Fig. 2 also shows the belt conveyor 10 (upper surface 11) and the waste plastic pieces WP on the belt conveyor 10.

[0032] The measuring unit 30 has a light irradiating unit 31 (light projecting unit) that irradiates infrared light 33 onto the waste plastic pieces WP passing through the irradiation area 31', and a light detecting unit 32 (light receiving unit) that detects reflected light 34 from the waste plastic pieces WP. The light irradiating unit 31 may include a light source such as a lamp, LED, or laser oscillator that emits light including infrared wavelengths. The light detecting unit 32 may be configured as an infrared spectroscopic camera that has a spectroscope that disperses the reflected light 34.

[0033] The measurement unit 30 irradiates the waste plastic pieces WP with infrared light 33 using the light irradiator 31 while the waste plastic pieces WP are passing through the irradiation area 31' on the belt conveyor 10. The infrared light 33 reflects off the surfaces of the waste plastic pieces WP, and the reflected light 34 enters the light detector 32. Depending on their material, the waste plastic pieces WP have the property of absorbing specific wavelengths of the irradiated infrared light 33 and reflecting other wavelengths. In this embodiment, this property is utilized to sort the waste plastic pieces WP. Therefore, the light irradiator 31 is preferably configured (adjusted) so that the infrared light 33 includes a specific wavelength range absorbed by the plastic material to be sorted. For example, if the plastic material to be sorted is ABS (acrylonitrile butadiene styrene resin), a wavelength range of 3.5 to 5.0 μm is appropriate for the infrared light 33. In addition, the light irradiation unit 31 may take measures to cut out unnecessary wavelengths of light that cause heat generation, etc., such as providing an optical filter that transmits only the infrared light emitted from the light source that has a wavelength used to classify the waste plastic pieces WP.

[0034] FIG. 3 shows an example of the configuration and operation of the light detection unit 32. The waste plastic pieces WP are transported on the belt conveyor 10 in the direction of arrow A. The light detection unit 32 includes a portion of the illumination area 31' as a detection area 32' (field of view range) and detects reflected light 34 from the waste plastic pieces WP passing through the detection area 32'. The detection area 32' is a predetermined area through which the waste plastic pieces WP transported on the belt conveyor 10 (on the transport path) pass. As described above, the light detection unit 32 of this embodiment is configured as an infrared spectroscopic camera having a spectrometer that disperses the reflected light 34, and may include a lens 32a, a mirror 32b, a slit 32c, a lens 32d, a diffraction grating 32e, and an image sensor 32f. The image sensor 32f is a photoelectric conversion element (image sensor, light receiving element) sensitive to infrared light and includes a light receiving surface 32g on which multiple pixels are two-dimensionally arranged.

[0035] Reflected light 34 from the waste plastic pieces WP in the detection area 32' is incident on the light-receiving surface 32g of the image sensor 32f via the lens 32a, mirror 32b, slit 32c, lens 32d, and diffraction grating 32e. In the light detection unit 32, the focal lengths of the lenses 32a and 32d are set so that the upper surface 11 of the belt conveyor 10, the slit 32c, and the light-receiving surface 32g are in an imaging relationship with each other, and the upper surface 11 of the belt conveyor 10 is imaged on the light-receiving surface 32g. The diffraction grating 32e has the property of diffracting light passing through it at different angles depending on the wavelength. This allows the wavelength distribution contained in the reflected light 34 to be projected two-dimensionally onto the light-receiving surface 32g of the image sensor 32f. Therefore, the light detection unit 32 (image sensor 32f) can generate a wavelength distribution image that visualizes the wavelength distribution of the reflected light 34 from the waste plastic pieces WP passing through (crossing) the detection area 32'. As described above, the wavelength distribution image generated by the light detection unit 32 is supplied to the processing unit 40, which converts the wavelength distribution image into a spectral waveform.

[0036] [Processing by identification device (identification processing)] The reflection characteristics of infrared light 33 may differ among the multiple waste plastic pieces WP transported on the belt conveyor 10 due to variations in surface properties. Specifically, the multiple waste plastic pieces WP include those with highly glossy surfaces (glossy surfaces) and those with less glossy surfaces (rough surfaces). Because the reflectance of infrared light 33 differs greatly between glossy surfaces and rough surfaces, a large difference occurs in the intensity of reflected light 34, which may make it difficult for the measuring unit 30 (light detecting unit 32) to accurately detect the reflected light 34.

[0037] For example, if the conditions for irradiating the waste plastic pieces WP with infrared light 33 are set according to the intensity of the reflected light 34 from the rough surface, the amount of light received by the light detection unit 32 (image sensor 32f) for the reflected light 34 from the glossy surface may be saturated. In this case, it may be difficult to accurately obtain a spectral waveform from the wavelength distribution image generated by the light detection unit 32. On the other hand, if the conditions for irradiating the waste plastic pieces WP with infrared light 33 are set according to the intensity of the reflected light 34 from the glossy surface, the amount of light received by the light detection unit 32 (image sensor 32f) for the reflected light 34 from the rough surface may be too small. In this case, it may also be difficult to accurately obtain a spectral waveform from the wavelength distribution image generated by the light detection unit 32.

[0038] Therefore, in the identification device of this embodiment, the measurement unit 30 irradiates the waste plastic piece WP with infrared light 33 under each of a plurality of different measurement conditions while the waste plastic piece WP passes through the detection area 32' (predetermined area) and measures the reflected light 34. Furthermore, the processing unit 40 identifies the type of the waste plastic piece WP based on the reflected light 34 under a measurement condition among the plurality of measurement conditions under which the amount of reflected light 34 measured by the measurement unit 30 falls within a specified range.

[0039] Here, the measurement conditions of the measurement unit 30 may include irradiation conditions under which the light irradiation unit 31 irradiates the waste plastic pieces WP with infrared light 33. In this case, the multiple measurement conditions have different irradiation conditions. The irradiation conditions may be conditions related to at least one of the irradiation intensity and irradiation time under which the light irradiation unit 31 irradiates the waste plastic pieces WP with infrared light 33. Furthermore, the measurement conditions of the measurement unit 30 may include, instead of or in addition to the irradiation conditions, light receiving conditions (detection conditions) under which the light detection unit 32 receives (detects) reflected light 34 from the waste plastic pieces WP. In this case, the multiple measurement conditions have different light receiving conditions. The light receiving conditions may be conditions related to at least one of the charge accumulation time and gain in the image sensor 32f of the light detection unit 32.

[0040] The process (identification process) performed by the identification device of this embodiment will be described below. In this embodiment, examples 1 to 3 will be described in which the irradiation conditions of the light irradiation unit 31 are changed as measurement conditions. The irradiation intensity (light intensity), irradiation time, and irradiation cycle of the infrared light 33 by the light irradiation unit 31 can be set independently and controlled in synchronization with the detection timing (imaging timing) of the reflected light 34 by the light detection unit 32.

[0041] [Example 1] In Example 1, an example will be described in which the irradiation intensity (light intensity) of the infrared light 33 on the waste plastic pieces WP is made different from one another under a plurality of measurement conditions. FIG. 4(a) shows the irradiation pattern of the infrared light 33 in the light irradiation unit 31 of Example 1. Here, under measurement condition C using the first irradiation intensity I1, 11 , measurement condition C using a second irradiation intensity I2 greater than the first irradiation intensity I1 12 and measurement condition C using a third irradiation intensity I3 greater than the second irradiation intensity I2. 13 Three types of measurement conditions are shown as examples. 11 ~C 13 Measurements can be performed sequentially under multiple measurement conditions C 11 ~C 13 In the example of FIG. 4(a), measurements under multiple measurement conditions C 11 ~C13 However, the measurement is not limited to this and may be performed continuously.

[0042] 4(b) shows the state in which the waste plastic pieces WP being transported on the belt conveyor 10 (on the transport path) pass through the irradiation area 31' and the detection area 32'. 11 ~C 13 1 shows the positional relationship between the waste plastic pieces WP and the detection area 32' at the measurement timing in . The measurement timing may be understood as the detection timing (imaging timing) of the reflected light 34 by the light detection unit 32. In this embodiment, while a waste plastic piece WP having the minimum size assumed to be transported by the belt conveyor 10 (hereinafter referred to as the assumed minimum size) passes through the detection area 32', the measurement of the reflected light 34 is performed under each measurement condition C. 11 ~C 13 Such measurement of the reflected light 34 can be achieved by controlling at least one of the measurement cycle of the reflected light 34 by the measuring unit 30 and the transport speed of the waste plastic pieces WP by the belt conveyor 10.

[0043] For example, if the belt moving speed of the belt conveyor 10 is V and the irradiation cycle of the infrared light 33 by the light irradiation unit 31 is i, the distance δL that the waste plastic piece WP travels during the irradiation cycle is "δL = V × i." If the total length of the waste plastic piece WP of the assumed minimum size is S, a total of (S / δL) measurements (irradiation of infrared light 33, detection of reflected light 34) will be performed while the waste plastic piece WP passes (crosses) the detection area 32' of the measurement unit 30 (light detection unit 32). Furthermore, if the number of measurement conditions (i.e., types of irradiation intensity of infrared light 33) is N, the number of measurements for each measurement condition for the waste plastic piece WP of the assumed minimum size will be "S / δL / N." In Figure 4(c), the positions where the reflected light 34 is measured on the waste plastic piece WP are indicated by dotted lines, and the number of measurements for each measurement condition C 11 ~C 13 The reflected light 34 is measured three times for each of the points.

[0044] The wavelength distribution image obtained by the image sensor 32f in each measurement is supplied to the processing unit 40 and stored in the memory unit of the processing unit 40. The processing unit 40 converts the wavelength distribution image obtained in each measurement into a spectral waveform. Then, the processing unit 40 identifies the type of waste plastic piece WP based on the reflected light 34 (spectral waveform) under measurement conditions among multiple measurement conditions under which the light amount of the reflected light 34 measured by the measurement unit 30 falls within a specified range R.

[0045] Figure 5 shows the measurement conditions C 11 ~C 13 Figure 5(a) shows an example of the spectrum waveform obtained under measurement condition C. 11 (First irradiation intensity I1) and Fig. 5(b) shows the spectrum waveform under measurement condition C 12 (second irradiation intensity I2), and Fig. 5(c) shows the spectral waveform under measurement condition C 13 For example, the processing unit 40 performs the measurement under each measurement condition C 11 ~C 13 The processing unit 40 calculates the average value of the spectral intensity for each of the spectral waveforms and selects a spectral waveform for which the average value falls within a specified range R. The processing unit 40 then calculates the correlation value between the selected spectral waveform and each type of reference spectral waveform, and identifies the type of reference spectral waveform for which the correlation value is equal to or greater than a predetermined value as the type of waste plastic piece WP. In other words, the type of waste plastic piece WP can be identified. The specified range R is the range of the light amount (or its average value) when the light amount of the reflected light 34 received by the image sensor 32f is not saturated or insufficient, and can be set in advance by experiment or simulation.

[0046] In this way, while the waste plastic pieces WP pass through the detection area 32', the measurement unit 30 of this embodiment 1 measures the reflected light 34 under each of a plurality of measurement conditions with different irradiation intensities of the infrared light 33. As a result, even if the intensities of the reflected light 34 differ for multiple waste plastic pieces WP, it is possible to accurately identify the type of each waste plastic piece WP and sort out a specific type of waste plastic piece WP from the multiple waste plastic pieces WP.

[0047] Here, the results of actually carrying out the identification process of this Example 1 will be described. The light detection unit 32 was further provided with a wavelength filter that transmits infrared light 33 with wavelengths of 3.5 to 5.0 μm, and a shutter that can be placed in the optical path of the infrared light 33 so as to switch between irradiating and blocking the infrared light 33. In addition, in the identification process, three types of measurement conditions C with different irradiation intensities of the infrared light 33 were used. 11 ~C 13 The conveying speed of the belt conveyor was 1 m / sec, the irradiation time of the infrared light 33 was 0.5 ms, and the irradiation cycle was 1 ms. In this case, a total of 100 measurements were taken while a waste plastic piece WP with a total length of 100 mm was passing through the detection area 32'. 11 ~C 13 33 wavelength distribution images were obtained for the three measurement conditions C 11 ~C 13 Among these, measurement conditions were selected under which the amount of reflected light 34 received by the image sensor 32f was within a specified range R (for example, a maximum below the saturation value), and a predetermined calculation process was performed on the wavelength distribution image under those measurement conditions to obtain a spectral waveform. Absorption specific to the material of the waste plastic pieces WP was observed at specific wavelengths in the obtained spectral waveform, and by comparing it with the reference spectral waveforms of each type stored in the processing unit 40, the type of waste plastic pieces WP could be identified.

[0048] [Example 2] In Example 2, an example will be described in which the irradiation time of the infrared light 33 to the waste plastic pieces WP is different from each other under a plurality of measurement conditions. FIG. 6 shows the irradiation pattern of the infrared light 33 in the light irradiation unit 31 of Example 2. Here, under measurement condition C using the first irradiation time T1, 21 Measurement condition C using a second irradiation time T2 longer than the first irradiation time T1 22 and measurement condition C using a third irradiation time T3 longer than the second irradiation time T2. 23 Three types of measurement conditions are shown as examples. 21 ~C 23 Measurements can be performed sequentially and intermittently under multiple measurement conditions C 21 ~C 23 One set of measurements can be repeated.

[0049] In this second embodiment, a plurality of measurement conditions C 21 ~C 23 In each measurement condition C, only the irradiation time of the infrared light 33 is changed, but in addition, the irradiation intensity of the infrared light 33 may be changed. 21 ~C 23 The irradiation time of the infrared light 33 in the measurement condition C is set to the time when the reflected light 34 is measured while the waste plastic piece WP of the assumed minimum size passes through the detection area 32′. 21 ~C 23 The number of times may be set arbitrarily as long as the number of times can be set at least once for each of the above.

[0050] Depending on the light source of the light irradiation unit 31, the wavelength distribution and light intensity of the infrared light 33 emitted from the light source may fluctuate, resulting in low stability in setting the irradiation intensity. Also, depending on the material of the waste plastic pieces WP, a suitable irradiation intensity may be required to cause the reflected light 34 to exhibit an absorption component specific to the material. In such cases, simply adjusting the irradiation intensity of the infrared light 33 according to the surface properties of the waste plastic pieces WP may not be enough to obtain a spectral waveform with an appropriate signal intensity, which may result in a decrease in the accuracy of identifying the type of waste plastic pieces WP. On the other hand, in this Example 2, a plurality of measurement conditions C 21 ~C 23In this case, the irradiation intensity of the infrared light 33 is kept constant at a predetermined value while the irradiation time is varied. This allows the identification process to be performed stably even if the stability of the light source of the light irradiation unit 31 is low. In other words, it is possible to stably obtain measurement conditions under which the amount of reflected light 34 measured by the measurement unit 30 (i.e., the amount of reflected light 34 incident on the light receiving surface 32g within the exposure time of the image sensor 32f) is within a specified range. As a result, it is possible to obtain a spectral waveform with appropriate signal intensity, and it becomes possible to accurately identify the type of waste plastic piece WP. Note that, under multiple measurement conditions C 21 ~C 23 The selection process using the above is the same as in the first embodiment, and therefore the description thereof will be omitted here.

[0051] [Example 3] In Example 3, an example will be described in which the measurement unit 30 (light irradiation unit 31) irradiates the waste plastic pieces WP with infrared light 33 as pulsed light, and the number of pulsed light beams to the waste plastic pieces WP is varied under a plurality of measurement conditions. FIG. 7 shows an irradiation pattern of the infrared light 33 in the light irradiation unit 31 in Example 3. Here, measurement condition C using a first number (3) of pulsed light beams is 31 Measurement condition C using a second number (four) of pulsed light beams, which is greater than the first number 32 and measurement condition C using a third number (6) of pulsed light beams, which is greater than the second number. 33 Three types of measurement conditions are shown as examples. 31 ~C 33 Measurements can be performed sequentially and intermittently under multiple measurement conditions C 31 ~C 33 One set of measurements can be repeated.

[0052] In this Example 3, multiple measurement conditions C 31 ~C 33 In the measurement conditions C, only the number of pulsed lights is changed, but in addition, the irradiation intensity of the pulsed light (infrared light 33) may be changed. Also, the interval G from the end of irradiation of pulsed light under one measurement condition to the start of irradiation of pulsed light under the next measurement condition is set to be equal to or greater than the interval G under each measurement condition C. 31 ~C33 The interval G and the irradiation period P can be set to be larger than the irradiation period P of the pulsed light under each measurement condition C. The interval G and the irradiation period P can be set to be larger than the irradiation period P of the pulsed light under each measurement condition C. 31 ~C 33 The number of times may be set arbitrarily as long as the number of times can be set at least once for each of the above.

[0053] The light source of the light irradiation unit 31 used in this Example 3 is, for example, a laser oscillator capable of oscillating pulsed light. The oscillation time of one pulsed light varies depending on the type (material) of the laser oscillator, but is, for example, 500 femtoseconds to 100 nanoseconds. In order to improve the throughput of the identification device, it is necessary to increase the amount of identification per unit time by expanding the detection area 32' (imaging field of view) of the light detection unit 32 as much as possible. Accordingly, it is also necessary to expand the irradiation area 31' of the light irradiation unit 31, but this increases the amount of infrared light 33. For example, if the light source of the light irradiation unit 31 is an infrared lamp, heat dissipation measures from the lamp may become extensive. Compared to an infrared lamp, a laser oscillator has the advantage of being able to instantaneously emit pulsed light with high brightness and of being able to suppress the temperature rise of the target object (waste plastic pieces WP). In other words, in this Example 3, a plurality of measurement conditions C 31 ~C 33 By varying the number of pulsed lights under the measurement conditions C, it is possible to accurately identify the type of waste plastic pieces WP while suppressing the temperature rise of the object. 31 ~C 33 The selection process using the above is the same as in the first embodiment, and therefore the description thereof will be omitted here.

[0054] As described above, the sorting device 100 (identification device) of this embodiment irradiates the waste plastic piece WP with infrared light 33 and measures the reflected light 34 under each of a plurality of different measurement conditions while the waste plastic piece WP passes through the detection area 32'. Then, the type of the waste plastic piece WP is identified based on the reflected light 34 under the measurement condition under which the amount of reflected light 34 measured by the measurement unit 30 falls within the specified range R. This makes it possible to accurately identify and classify the type of each waste plastic piece WP even if there is variation in the surface properties of the plurality of waste plastic pieces WP being transported on the belt conveyor 10.

[0055] Second Embodiment A second embodiment of the present invention will be described. In this embodiment, an example of controlling the measurement cycle of reflected light 34 in the measurement unit 30 and / or the transport speed of waste plastic pieces WP by the belt conveyor 10 will be described. Note that this embodiment basically inherits the first embodiment, and can follow the first embodiment except for the matters mentioned below.

[0056] First, an example of controlling the measurement cycle of reflected light 34 in measurement unit 30 will be described. A measurement cycle refers to a period (timing) for switching measurement conditions for measuring reflected light 34, and may be understood as the period from the end of measurement of reflected light 34 under one measurement condition to the start of measurement of reflected light 34 under the next measurement condition. FIG. 8 is a flowchart showing a method for controlling the measurement cycle of reflected light 34 in measurement unit 30. The flowchart in FIG. 8 can be executed by processing unit 40.

[0057] In step S11, the processing unit 40 acquires speed information indicating the transport speed of the waste plastic pieces WP transported on the belt conveyor 10. The speed information may be understood as information indicating the speed of the belt of the belt conveyor 10. For example, the processing unit 40 may acquire the speed information based on the speed of the belt conveyor 10 (belt) set by the user via the user interface 41, or based on the results of detecting the rotation speed of the motor driving the belt conveyor 10 or the speed of the belt.

[0058] In step S12, the processing unit 40 acquires dimensional information indicating the assumed minimum dimensions of the waste plastic pieces WP transported on the belt conveyor 10. For example, the dimensional information may be information input by a user via the user interface 41. Note that step S12 may be omitted if the dimensional information is already stored in the processing unit 40, such as when dimensional information used in a previous identification process can be reused.

[0059] In step S13, the processing unit 40 determines the measurement cycle of the reflected light 34 in the measurement unit 30 based on the speed information acquired in step S11 and the dimension information acquired in step S12. Specifically, the processing unit 40 determines the measurement cycle based on the speed information and dimension information so that measurement of the reflected light 34 is performed at least once under each of a plurality of measurement conditions while a waste plastic piece WP of the assumed smallest dimension passes through the detection area 32'. To determine the measurement cycle, for example, the mathematical formula described in the first embodiment can be used. Next, in step S14, the processing unit 40 controls the measurement unit 30 so that measurement of the reflected light 34 is performed using the measurement cycle determined in step S13.

[0060] Next, an example of controlling the transport speed of the waste plastic pieces WP by the belt conveyor 10 will be described. The transport speed of the waste plastic pieces WP may be understood as the speed of the belt of the belt conveyor 10. FIG. 9 is a flowchart showing a method of controlling the transport speed of the waste plastic pieces WP by the belt conveyor 10. The flowchart in FIG. 8 can be executed by the processing unit 40.

[0061] In step S21, the processing unit 40 acquires measurement information indicating the measurement cycle of the reflected light 34 in the measuring unit 30. For example, the measurement information may be information input by a user via the user interface 41. Next, in step S22, the processing unit 40 acquires dimensional information indicating the assumed minimum dimensions of the waste plastic pieces WP transported on the belt conveyor 10. For example, the dimensional information may be information input by a user via the user interface 41. Note that step S22 may be omitted if the dimensional information is already stored in the processing unit 40, such as when dimensional information used in a previous identification process can be reused.

[0062] In step S23, the processing unit 40 determines the conveying speed of the waste plastic pieces WP by the belt conveyor 10 based on the measurement information acquired in step S21 and the dimensional information acquired in step S22. Specifically, the processing unit 40 determines the conveying speed based on the measurement information and dimensional information so that measurement of the reflected light 34 is performed at least once under each of multiple measurement conditions while a waste plastic piece WP of the assumed smallest dimension passes through the detection area 32'. To determine the conveying speed, for example, the formula described in the first embodiment can be used. Next, in step S24, the processing unit 40 controls the belt conveyor 10 so that the waste plastic pieces WP are conveyed at the conveying speed determined in step S23.

[0063] <Embodiment of an article manufacturing method> The sorting device (identification device) according to the above embodiment can be used in an article manufacturing method for manufacturing articles such as plastic products. This article manufacturing method includes, for example, a sorting step of sorting plastic pieces using the above sorting device (identification device), and a manufacturing step of manufacturing articles by processing the plastic pieces sorted in the sorting step. The processing of the plastic pieces can include, for example, at least one of melting, molding, cutting, assembly, and inspection. The article manufacturing method according to the present embodiment is advantageous over conventional methods in terms of article performance, quality, productivity, production costs, and the like.

[0064] <Summary of the embodiment> The disclosure of the present specification includes at least the following identification device, classification device, identification method, classification method, and article manufacturing method. (Item 1) An identification device that identifies the type of plastic piece being transported on a transport path, a measuring unit that irradiates the plastic pieces with infrared light and measures the reflected light from the plastic pieces under each of a plurality of different conditions while the plastic pieces are passing through a predetermined area on the conveying path; a processing unit that identifies the type of the plastic piece based on the reflected light under a condition where the amount of reflected light measured by the measuring unit falls within a specified range among the plurality of conditions; and An identification device comprising: (Item 2) The identification device described in item 1, characterized in that the processing unit controls the measurement cycle of the reflected light in the measurement unit based on information indicating the transport speed of the plastic piece transported on the transport path so that the measurement of the reflected light is performed at least once under each of the multiple conditions while the plastic piece is passing through the specified area. (Item 3) 3. The identification device according to item 2, wherein the processing unit controls the measurement cycle of the reflected light in the measurement unit based on information indicating the minimum dimensions of the plastic pieces expected to be transported on the transport path. (Item 4) The identification device described in item 1, characterized in that the processing unit controls the conveying speed of the plastic piece on the conveying path based on information indicating the measurement cycle of the reflected light in the measurement unit so that measurement of the reflected light is performed at least once under each of the multiple conditions while the plastic piece is passing through the specified area. (Item 5) 5. The identification device according to item 4, wherein the processing unit controls the conveying speed of the plastic piece on the conveying path based further on information indicating the minimum dimensions of the plastic piece expected to be conveyed on the conveying path. (Item 6) 6. The identification device according to any one of items 1 to 5, wherein the measurement unit includes a spectroscope that separates the reflected light. (Item 7) 7. The identification device according to any one of items 1 to 6, wherein the plurality of conditions are different irradiation conditions for irradiating the plastic piece with the infrared light. (Item 8) 8. The identification device according to item 7, wherein the irradiation conditions include at least one of the irradiation intensity and irradiation time of the infrared rays. (Item 9) The measuring unit irradiates the plastic piece with the infrared light as pulsed light, 9. The identification device according to item 7 or 8, wherein the irradiation conditions include the number of pulsed lights. (Item 10) 10. The identification device according to any one of items 1 to 9, wherein the plurality of conditions are different from one another in terms of conditions under which the measurement unit receives the reflected light. (Item 11) A sorting device for sorting a plurality of plastic pieces by type, a conveying mechanism for conveying the plurality of plastic pieces on a conveying path; The identification device according to any one of items 1 to 10, which identifies the type of each of the plurality of plastic pieces being transported on the transport path by the transport mechanism; a sorting mechanism that sorts the plurality of plastic pieces transported by the transport mechanism by type based on the identification result of the identification device; A classification device comprising: (Item 12) a detection unit that detects the position of each of the plurality of plastic pieces on the conveying path; Item 12. The sorting device according to item 11, wherein the sorting mechanism further sorts the plurality of plastic pieces transported by the transport mechanism by type based on the detection result of the detection unit. (Item 13) A sorting step of sorting plastic pieces using the sorting device according to item 11 or 12; a manufacturing step of manufacturing an article by processing the plastic pieces sorted in the sorting step; A method for manufacturing an article, comprising: (Item 14) A method for identifying the type of plastic pieces being transported on a transport path, comprising: a measuring step of irradiating the plastic pieces with infrared light and measuring the reflected light from the plastic pieces under each of a plurality of different conditions while the plastic pieces are passing through a predetermined area on the conveying path; an identification step of identifying the type of the plastic piece based on the reflected light under a condition where the amount of reflected light measured in the measurement step falls within a specified range among the plurality of conditions; 10. A method for identifying a target object, comprising: (Item 15) A classification method for classifying a plurality of plastic pieces by type, comprising: An identification step of identifying the type of each of the plurality of plastic pieces being transported on a transport path using the identification method according to item 14; a sorting step of sorting the plurality of plastic pieces conveyed along the conveying path by type based on the identification result of the identification step; A classification method comprising:

[0065] The technology described in this specification can contribute to the realization of a sustainable society, such as a decarbonized / recycling-based society.

[0066] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0067] 10: Belt conveyor, 20: Detection unit, 30: Measurement unit, 31: Light irradiation unit, 32: Light detection unit, 40: Processing unit, 50: Sorting unit, 60: Driving unit, 100: Classification device

Claims

1. An identification device that identifies the type of plastic piece being transported on a transport path, a measuring unit that irradiates the plastic pieces with infrared light and measures the reflected light from the plastic pieces under each of a plurality of different conditions while the plastic pieces are passing through a predetermined area on the conveying path; a processing unit that identifies the type of the plastic piece based on the reflected light under a condition where the amount of reflected light measured by the measuring unit falls within a specified range among the plurality of conditions; and An identification device comprising:

2. The identification device described in claim 1, characterized in that the processing unit controls the measurement cycle of the reflected light in the measurement unit based on information indicating the conveying speed of the plastic piece conveyed on the conveying path so that the reflected light is measured at least once under each of the plurality of conditions while the plastic piece is passing through the specified area.

3. 3. The identification device according to claim 2, wherein the processing unit controls the measurement cycle of the reflected light in the measurement unit further based on information indicating the minimum size of the plastic piece expected to be transported on the transport path.

4. The identification device according to claim 1, characterized in that the processing unit controls the transport speed of the plastic piece on the transport path based on information indicating the measurement cycle of the reflected light in the measurement unit so that measurement of the reflected light is performed at least once under each of the plurality of conditions while the plastic piece is passing through the specified area.

5. The identification device according to claim 4, characterized in that the processing unit controls the conveying speed of the plastic piece on the conveying path further based on information indicating the minimum size of the plastic piece expected to be conveyed on the conveying path.

6. 2. The identification device according to claim 1, wherein the measurement unit includes a spectroscope that separates the reflected light.

7. 2. The identification device according to claim 1, wherein the plurality of conditions are different from one another in irradiation conditions for irradiating the plastic piece with the infrared light.

8. 8. The identification device according to claim 7, wherein the irradiation conditions include at least one of an irradiation intensity and an irradiation time of the infrared rays.

9. The measuring unit irradiates the plastic piece with the infrared light as pulsed light, 8. The identification device according to claim 7, wherein the irradiation conditions include the number of pulsed lights.

10. The identification device according to claim 1 , wherein the plurality of conditions are different from one another in terms of conditions under which the measurement unit receives the reflected light.

11. A sorting device for sorting a plurality of plastic pieces by type, a conveying mechanism for conveying the plurality of plastic pieces on a conveying path; The identification device according to any one of claims 1 to 10, which identifies the type of each of the plurality of plastic pieces being transported on the transport path by the transport mechanism; a sorting mechanism that sorts the plurality of plastic pieces transported by the transport mechanism by type based on the identification result of the identification device; A classification device comprising:

12. a detection unit that detects the position of each of the plurality of plastic pieces on the conveying path; 12. The sorting device according to claim 11, wherein the sorting mechanism sorts the plurality of plastic pieces transported by the transport mechanism by type, further based on the detection result of the detection unit.

13. a sorting step of sorting plastic pieces using the sorting device of claim 11; a manufacturing step of manufacturing an article by processing the plastic pieces sorted in the sorting step; A method for manufacturing an article, comprising:

14. A method for identifying the type of plastic pieces being transported on a transport path, comprising: a measuring step of irradiating the plastic pieces with infrared light and measuring the reflected light from the plastic pieces under each of a plurality of different conditions while the plastic pieces are passing through a predetermined area on the conveying path; an identification step of identifying the type of the plastic piece based on the reflected light under a condition where the amount of reflected light measured in the measurement step falls within a specified range among the plurality of conditions; 10. A method for identifying a target object, comprising:

15. A classification method for classifying a plurality of plastic pieces by type, comprising: an identifying step of identifying the type of each of the plurality of plastic pieces being transported on a transport path using the identifying method according to claim 14; a sorting step of sorting the plurality of plastic pieces conveyed along the conveying path by type based on the identification result of the identification step; A classification method comprising:

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