Sorting processing device and sorting processing method

Abstract

A sorting processing device according to the present disclosure comprises: a first recovery unit that recovers a first recovered material that is a part of a sorted mixture; a second recovery unit that recovers a second recovered material that is a part of the mixture; a first conveyance unit that conveys the first recovered material; a second conveyance unit that conveys the second recovered material; one sensor that irradiates the first conveyance unit and the second conveyance unit with light and detects reflected light; and a processing unit that processes a detection result from the sensor and calculates a composition ratio by type of plastic fragment in the first recovered material and the second recovered material.

Description

Sorting Processing Apparatus and Sorting Processing Method

[0001] The present disclosure relates to a sorting processing apparatus and a sorting processing method.

[0002] Patent Document 1 discloses a sorting processing apparatus for sorting plastic pieces. The sorting processing apparatus has a part for collecting the sorted plastic pieces. In the example of Patent Document 1, the collection container has three collection compartments. The sorted plastic pieces are collected in these collection compartments.

[0003] Japanese Patent Application Laid-Open No. 2018-65123

[0004] In the sorting processing apparatus, in order to improve the sorting accuracy, information such as the composition ratio regarding the sorted plastic pieces may be acquired. To acquire such information, sensors are used. Here, for example, when three sensors are arranged to acquire the composition ratio etc. for each of the three collection compartments shown in Patent Document 1, there is a problem that costs, installation space, etc. increase.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a sorting processing apparatus and a sorting processing method capable of reducing the number of sensors.

[0006] One aspect of the sorting processing apparatus according to the present disclosure is a sorting processing apparatus that sorts a mixture containing a plurality of types of plastic pieces for each type of the plastic pieces, including a first collection unit that collects a first collection product that is a part of the sorted mixture, a second collection unit that collects a second collection product that is a part of the sorted mixture, a first conveyance unit that conveys the first collection product from the first collection unit, a second conveyance unit that is arranged side by side with the first conveyance unit and conveys the second collection product from the second collection unit, one sensor that is arranged outside the first collection unit and the second collection unit, irradiates light on the first conveyance unit and the second conveyance unit, and detects reflected light, and a processing unit that processes the detection result by the sensor and calculates the composition ratio for each type of the plastic pieces in the first collection product and the second collection product.

[0007] One embodiment of the sorting method according to the present disclosure is a sorting method for sorting a mixture containing multiple types of plastic pieces according to the type of plastic piece, wherein a first recovered material and a second recovered material, which are part of the sorted mixture, are transported by a first transport unit and a second transport unit arranged side by side, and a single sensor detects the first recovered material on the first transport unit and the second recovered material on the second transport unit, and the composition ratio of each type of plastic piece in the first recovered material and the second recovered material is calculated based on the detection result of the sensor.

[0008] According to this disclosure, a sorting processing device and a sorting processing method can be provided that can reduce the number of sensors.

[0009] This figure shows an example of the configuration of the sorting apparatus in Embodiment 1. This figure shows an example of the configuration around the detection unit in Embodiment 1. This figure illustrates a method for calculating the composition ratio from HSI data. This figure illustrates an example of applying the method in Figure 3 to the detection unit in Embodiment 1. This figure shows an example of the configuration around the detection unit in Embodiment 2.

[0010] Embodiment 1. Embodiments of the present disclosure will be described below with reference to the drawings. The scope of the present disclosure is not limited to the following embodiments and can be arbitrarily modified within the scope of the technical idea of ​​the present disclosure. Figure 1 is a diagram illustrating the configuration of the sorting processing apparatus 1 in Embodiment 1. The sorting processing apparatus 1 comprises an input unit 121, a charging cylinder 122, a vibrating feeder 123, a first electrode 124, a second electrode 125, a DC power supply 126, a collection box 127, partition plates 128, 129, a raw material detection unit 11, a detection unit 12, a calculation unit 13, and a control unit 14. However, the configuration of the sorting processing apparatus 1 in Figure 1 is merely an example and can be modified.

[0011] In the following, the positional relationships of each component may be explained using the XYZ Cartesian coordinate system. In Figure 1, etc., the X direction is the direction in which the X partition plates 128 and 129 are arranged. The Z direction is the vertical direction. The Y direction is perpendicular to both the X and Z directions. However, the arrangement of each component in Figure 1, etc. is just an example and can be changed.

[0012] The sorting and processing device 1 is configured to sort a mixture containing multiple types of objects according to the type of object. In this embodiment, a group of plastic pieces P is used as an example of a "mixture containing multiple types of objects". In the example in Figure 1, the group of plastic pieces P contains two types of plastic pieces p1 and p2 made of different materials. In this specification, the materials of the plastic pieces p1 and p2 may not be distinguished and they may be referred to as "flakes". Three or more types of plastic pieces may be included in the group of plastic pieces P. In other words, the sorting and processing device 1 may sort three or more types of plastic pieces.

[0013] As an example, the sorting and processing device 1 electrostatically separates a group of plastic pieces P, which consists of multiple types of plastic pieces p1 and p2 with different electrostatic properties, into plastic pieces p1 and plastic pieces p2. In the following explanation, we will use the case where plastic piece p1 is ABS and plastic piece p2 is PS as an example. Plastic pieces p1 and p2 are obtained, for example, by crushing and drying the casing of a home appliance using a crusher. Plastic pieces p1 and p2 are formed to a size of, for example, about 10 mm square.

[0014] The input section 121 includes a hopper 121a and an input feeder 121b. Dried plastic pieces P are supplied to the hopper 121a. The hopper 121a supplies a predetermined amount of plastic pieces P per unit time to the input feeder 121b. The input feeder 121b supplies the plastic pieces P fed from the hopper 121a into the electrostatic cylinder 122.

[0015] The charging cylinder 122 and the vibrating feeder 123 constitute the charging unit 2. The charging unit 2 charges each of the plastic pieces p1 and p2 before sorting and then drops them. Specifically, the charging cylinder 122 agitates the group of plastic pieces P by rotating. Inside the charging cylinder 122, multiple types of plastic pieces p1 and p2 mixed in the group of plastic pieces P become charged by friction with each other. Each of the charged plastic pieces p1 and p2 has a charge amount of polarity (positive or negative) according to the triboelectric series. In this example, the plastic piece p1, which is ABS, becomes positively charged, and the plastic piece p2, which is PS, becomes negatively charged.

[0016] The charged plastic pieces p1 and p2 are supplied to the rear end of the upper surface of the vibrating feeder 123. The positively charged plastic piece p1 and the negatively charged plastic piece p2 may attract each other due to electrostatic force and pair up. The vibrating feeder 123 pushes the plastic pieces p1 and p2 forward while vibrating them up and down. This disengages the pairing of the plastic pieces p1 and p2, and the plastic pieces p1 and p2 move in the X direction in the figure. The plastic pieces p1 and p2 also fall from the vibrating feeder 123.

[0017] Electrodes 124, 125 and a DC power supply 126 constitute the electric field generating unit 3. The electric field generating unit 3 applies an electrostatic field to each charged plastic piece p1, p2. As a result, each plastic piece p1, p2 falls to a position corresponding to its respective charge state. Specifically, electrodes 124 and 125 are formed in a flat plate shape. Electrodes 124 and 125 are arranged in the X direction in the figure and are positioned facing each other, straddling the path through which the plastic pieces p1, p2 fall. A ground voltage GND is applied to the first electrode 124. The DC power supply 126 applies a predetermined DC voltage between the first electrode 124 and the second electrode 125, generating an electrostatic field between the first electrode 124 and the second electrode 125.

[0018] When the plastic pieces p1 and p2, whose pairing has been broken by the vibrating feeder 123, are dropped between electrodes 124 and 125, each plastic piece falls while being attracted to either electrode 124 or electrode 125 by an electrostatic force corresponding to its charge state (polarity, amount of charge). In other words, each plastic piece p1 and p2 traces a parabolic trajectory corresponding to its charge state and falls to a different position. In this example, since plastic piece p1 is positively charged, it falls towards the first electrode 124. On the other hand, since plastic piece p2 is negatively charged, it falls towards the second electrode 125.

[0019] The collection box 127 is located below the electrodes 124 and 125 and collects the plastic pieces p1 and p2 that have fallen from the vibrating feeder 123 through the space between the electrodes 124 and 125. The top of the collection box 127 is open. The opening of the collection box 127 is formed, for example, in a rectangular shape, with its long side aligned along the X direction in the figure.

[0020] Each of the partition plates 128 and 129 is also referred to as a partition member. The partition plates 128 and 129 are arranged parallel to the YZ plane in the figure within the collection box 127 and are movable in the X direction in the figure. The position of each of the partition plates 128 and 129 in the X direction is controlled by the control unit 14. In the X direction, partition plate 128 is located on the first electrode 124 side, and partition plate 129 is located on the second electrode 125 side. The collection box 127 is divided by the partition plates 128 and 129 into a first collection section 127a on the first electrode 124 side, a second collection section 127b on the second electrode 125 side, and an intermediate third collection section 127c.

[0021] Each plastic piece p1 and p2 that falls from the vibrating feeder 123 through the electrodes 124 and 125 is collected in one of three collection units 127a to 127c depending on its charge state. In this example, plastic piece p1 is positively charged and is collected in the first collection unit 127a. On the other hand, plastic piece p2 is negatively charged and is collected in the second collection unit 127b. Plastic pieces p1 and p2 that are not sufficiently charged are collected in the third collection unit 127c.

[0022] The raw material detection unit 11, detection unit 12, calculation unit 13, and control unit 14 are connected to each other by wire or wireless connection so that they can communicate with one another. The raw material detection unit 11 inputs raw material information to the calculation unit 13. The detection unit 12 inputs recovered material information to the calculation unit 13. In this specification, "raw material" refers to the mixture (group of plastic pieces P) before sorting. "Recovered material" refers to the mixture sorted by type of plastic piece and contained in the collection box 127. "Raw material information" refers to information about the raw material. Examples of raw material information include the composition ratio, supply amount, and specific charge of the plastic pieces p1 and p2 contained in the raw material. "Recovered material information" refers to information about the recovered material. The recovered material information will be described later.

[0023] "Raw material information" may, for example, be the specific charge of the raw material after charging. Alternatively, "raw material information" may be the composition ratio of the raw material. The raw material detection unit 11 is equipped with sensors for acquiring raw material information. For example, when detecting specific charge, the raw material detection unit 11 is equipped with a weight sensor and a charge amount sensor. For example, when detecting composition ratio, the raw material detection unit 11 is equipped with a sensor capable of detecting the type of plastic piece.

[0024] The calculation unit 13 calculates setting values ​​for sorting conditions based on raw material information and recovered material information. The calculation unit 13 outputs the setting values, which are the result of the calculation, to the control unit 14. The control unit 14 controls the sorting conditions of the sorting processing device 1 based on the setting values ​​input from the calculation unit 13. For example, the control unit 14 may control the positions of the partition plates 128 and 129 in the X direction. Alternatively, the control unit 14 may control the rotational speed or tilt of the charging cylinder 122, the voltage applied by the DC power supply 126 to the second electrode 125, etc. In other words, the "setting values" are the positions of the partition plates 128 and 129 in the X direction, the rotational speed or tilt of the charging cylinder 122, the voltage of the DC power supply 126, etc. The "setting values" may include multiple of these parameters.

[0025] As shown in Figure 2, the sorting and processing device 1 is equipped with a conveyor 130. The conveyor 130 is, for example, a belt conveyor. The conveyor 130 transports the collected materials to the collection sections 127a to 127c. In the example in Figure 2, the transport direction by the conveyor 130 coincides with the Y direction. Hereafter, the plastic pieces collected in the first collection section 127a will be referred to as "first collected materials". Similarly, the plastic pieces collected in the second collection section 127b and the third collection section 127c will be referred to as "second collected materials" and "third collected materials," respectively.

[0026] In the example shown in Figure 2, an opening 127d is formed at the bottom of the collection box 127. A part of the conveyor 130 is located below the opening 127d. The collected material that falls from the opening 127d is placed on the conveyor 130. Here, the conveyor 130 conveys the first, second, and third collected materials in a way that prevents them from mixing. Specifically, the upper surface of the conveyor 130 is divided into a first conveying section X1, a second conveying section X2, and a third conveying section X3. The first collected material collected in the first collection section 127a is placed on the first conveying section X1. The second collected material collected in the second collection section 127b is placed on the second conveying section X2. The third collected material collected in the third collection section 127c is placed on the third conveying section X3.

[0027] In this embodiment, the recovered materials that fall from the recovery sections 127a to 127c through the opening 127d are placed on the conveyor 130 without changing their position in the X direction. This prevents the first, second, and third recovered materials from mixing on the conveyor 130. The conveyor 130 may be provided with partitions separating the conveyor sections X1 to X3. In this case, the mixing of the first, second, and third recovered materials is more reliably prevented. Alternatively, the sorting and processing device 1 may be equipped with three independent conveyors, each corresponding to the recovery sections 127a to 127c. In this case, the upper surfaces of the three conveyors become independent conveyor sections X1 to X3. In this case, the three conveyors are arranged in the X direction.

[0028] The detection unit 12 detects information about the recovered materials contained in each of the recovery units 127a to 127c as recovered material information. The following describes the case where the "recovered material information" is information about the composition ratio of the recovered materials. As shown in Figure 2, the detection unit 12 has a sensor 12a and a processing unit 12b. The sensor 12a and the processing unit 12b are connected by wire or wireless connection and can send and receive signals. The sensor 12a is, for example, a hyperspectral camera. The hyperspectral camera as sensor 12a images the recovered materials flowing on the conveyor 130 in a line scan manner. The sensor 12a is located outside the recovery box 127. In this embodiment, the sensor 12a can simultaneously image the three conveyor units X1 to X3. That is, the detection range of the sensor 12a in the X direction spans the three conveyor units X1 to X3.

[0029] The hyperspectral camera, acting as sensor 12a, spectrally analyzes the light emitted from each point of the flakes contained in the first to third collected materials, which are the subject of the experiment, and captures it on the sensor surface. Multiple pixels are arranged on the sensor surface, and each pixel captures light of a different wavelength. The hyperspectral camera outputs HSI data based on the intensity of light at each wavelength. HSI stands for hyperspectral imaging. The HSI data includes the infrared spectrum for each pixel. The infrared spectrum is information about the spectrum in the near-infrared region.

[0030] Figures 3(A) to 3(C) show an example of calculating the composition ratio of plastic fragments using HSI data from a hyperspectral camera. As shown in Figure 3(A), the HSI data contains pixel-by-pixel spectral information associated with the shape of the flakes. In Figure 3(A), points (i) and (ii) are parts of the flakes, and point (iii) is a region where no flakes are present. Figure 3(A1) shows the pixel-by-pixel spectra of points (i) to (iii). In each graph in Figure 3(A1), for example, the horizontal axis represents wavelength, and the vertical axis represents intensity at each wavelength.

[0031] Figure 3(B) is an example of an image generated by analyzing the HSI data in Figure 3(A). In the image in Figure 3(B), flakes containing point (i) are displayed in red, and flakes containing point (ii) are displayed in blue. In other words, Figure 3(B) is an image after color conversion based on the infrared spectrum of each pixel contained in the HSI data in Figure 3(A). In the image in Figure 3(B), for example, the red flakes are plastic pieces p1, and the blue flakes are plastic pieces p2.

[0032] Further image analysis of the image in Figure 3(B) allows us to determine the area ratio for each color. From the area ratio for each color, we can estimate the composition ratio for each type of plastic piece. In the example in Figure 3(B), the ratio of the area of ​​the red region to the area of ​​the blue region is 60:40. Therefore, for this group of plastics, we can determine that the composition ratio of plastic piece p1 is 60% and the composition ratio of plastic piece p2 is 40%.

[0033] As explained using Figure 3, the composition ratio of the target plastic fragments can be obtained by performing a predetermined process on the HSI data. In this embodiment, the above acquisition method is applied to the detection unit 12 shown in Figure 2. Specifically, as shown in Figures 4(A) to (C), the composition ratio of plastic fragments in the recovered material can be calculated corresponding to each of the transport units X1 to X3. Specifically, as shown in Figure 4(A), the HSI data obtained by the sensor 12a includes regions corresponding to each of the transport units X1 to X3.

[0034] The processing unit 12b performs infrared spectral analysis on the HSI data shown in Figure 4(A). As a result, as shown in Figure 4(B), an image is obtained in which each region corresponding to the transport units X1 to X3 is color-coded according to the type of plastic piece. In Figure 4(B), flakes that do not correspond to either plastic pieces p1 or p2 are displayed as a third type of plastic piece p3.

[0035] For the image shown in Figure 4(B), the processing unit 12b performs image analysis to determine the area ratio for each color and converts it into a composition ratio for each type of plastic piece. As a result, as shown in Figure 4(C), the composition ratio of plastic pieces for each region of the image, i.e., for each transport unit X1 to X3, is obtained. In this way, the detection unit 12 sequentially measures the composition ratio of the recovered materials collected in the recovery units 127a to 127c using a line scan method. The obtained composition ratios are input to the calculation unit 13 as recovered material information. The calculation unit 13 performs feedback control based on the recovered material information to calculate setting values ​​for sorting conditions so as to satisfy predetermined requirements. These predetermined requirements include, for example, sorting accuracy and recovery efficiency.

[0036] In Figure 4(B), one image contains regions corresponding to the transport units X1 to X3. As a modification, the processing unit 12b may crop the image shown in Figure 4(B) to generate three images corresponding to the transport units X1 to X3. In this case, the processing unit 12b can calculate the composition ratio by performing image analysis on each of the three images. Also, although the composition ratios of three types of plastic pieces p1, p2, and p3 are calculated in Figures 4(A) to (C), the composition ratios of only two types of plastic pieces p1 and p2 may also be calculated.

[0037] According to the configuration of the detection unit 12 shown in Figure 2, the composition ratio can be detected for the entire amount of each recovered material from the recovery units 127a to 127c. However, it is also possible to extract only a portion of the recovered material from the recovery units 127a to 127c and perform detection by the detection unit 12. In this case, the sorting and processing device 1 may have a structure for extracting a portion of the recovered material from the recovery units 127a to 127c and placing it on the conveyor 130.

[0038] Each of the functions of the processing unit 12b, the arithmetic unit 13, the control unit 14, etc., is realized by a processor such as a CPU (Central Processing Unit) executing a program stored in program memory. Some or all of these functions may be realized by hardware such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), or FPGA (Field-Programmable Gate Array), or by the cooperation of software and hardware. The functions of the processing unit 12b, the arithmetic unit 13, and the control unit 14 may be realized by the same hardware. Some of the functions of the processing unit 12b, the arithmetic unit 13, the control unit 14, etc., may be realized by a device such as a cloud.

[0039] As described above, the sorting and processing apparatus 1 according to this disclosure sorts a mixture containing multiple types of plastic pieces according to the type of plastic piece. The sorting and processing apparatus 1 comprises a first recovery unit 127a, a second recovery unit 127b, a first transport unit X1, a second transport unit X2, a sensor 12a, and a processing unit 12b. The first recovery unit 127a recovers a first recovery material, which is a part of the sorted mixture. The second recovery unit 127b recovers a second recovery material, which is a part of the sorted mixture. The first transport unit X1 transports the first recovery material from the first recovery unit 127a. The second transport unit X2 is arranged next to the first transport unit X1 and transports the second recovery material from the second recovery unit 127b. The sensor 12a is arranged outside the first recovery unit 127a and the second recovery unit 127b and irradiates the first transport unit X1 and the second transport unit X2 with light and detects the reflected light. The processing unit 12b processes the detection results from the sensor 12a and calculates the composition ratio of each type of plastic fragment in the first and second recovered materials.

[0040] Furthermore, the sorting process method according to this disclosure comprises a sorting step, a transport step, a detection step, and a calculation step. In the sorting step, a mixture containing multiple types of plastic pieces is sorted according to the type of plastic piece. In the transport step, the first recovered material and the second recovered material, which are part of the sorted mixture, are transported by a first transport unit X1 and a second transport unit X2 arranged side by side. In the detection step, the first recovered material on the first transport unit X1 and the second recovered material on the second transport unit X2 are detected by a single sensor 12a. In the calculation step, the composition ratio of each type of plastic piece in the first recovered material and the second recovered material is calculated based on the detection result of the sensor 12a.

[0041] According to the sorting processing device 1 or sorting processing method of this disclosure, the composition ratio of multiple recovered materials can be calculated using the detection result of a single sensor 12a. Therefore, the number of sensors can be reduced.

[0042] The sorting and processing device 1 further comprises a third recovery unit 127c and a third transport unit X3. The third recovery unit 127c is located between the first recovery unit 127a and the second recovery unit 127b and recovers a third recovered material, which is part of the sorted mixture. The third transport unit X3 is located between the first transport unit X1 and the second transport unit X2 and transports the third recovered material from the third recovery unit 127c. The sensor 12a irradiates the third transport unit X3 with light and detects the reflected light. The processing unit 12b processes the detection results from the sensor 12a and calculates the composition ratio of each type of plastic piece in the third recovered material. With this configuration, the composition ratio of three recovered materials can be obtained using one sensor 12a. Therefore, the number of sensors can be further reduced.

[0043] Furthermore, the sensor 12a may be a hyperspectral camera. This allows for efficient acquisition of the composition ratio of the recovered material using a line scan method. However, the sensor 12a is not limited to a hyperspectral camera, as long as it can detect the type of plastic fragment.

[0044] Further, the processing unit 12b calculates the composition ratio for each type of plastic piece in the first collected material and the second collected material based on the area ratio for each type of plastic piece included in the first collected material and the second collected material. Thereby, compared with the case of calculating the composition ratio based on the weight of the plastic pieces, it is possible to reduce the sensors for measuring the weight.

[0045] Embodiment 2. Next, a sorting processing apparatus according to Embodiment 2 will be described. Since the basic configuration of the sorting processing apparatus according to the present embodiment is the same as that of the sorting processing apparatus of Embodiment 1, the description will focus on the differences. As shown in FIG. 5, in the present embodiment, the configuration of the detection unit 12 is different from that of Embodiment 1.

[0046] In the present embodiment, the conveyor 130 has a raw material conveyor section X4 in addition to the conveyor sections X1 to X3 similar to those in Embodiment 1. The raw material conveyor section X4 is a part that conveys a part of the raw material. For example, a part of the raw material flowing on the vibration feeder 123 (see FIG. 1) may be extracted and placed on the raw material conveyor section X4 of the conveyor 130. The raw material conveyor section X4 is arranged side by side with the conveyor sections X1 to X3 in the X direction. The raw material conveyor section X4 may be a conveyor independent of the first to third conveyor sections X1.

[0047] In the example of FIG. 5, the detection range of the sensor 12a in the X direction is smaller than the width of the conveyor 130 in the X direction. In the present embodiment, the sensor 12a is movable in the X direction. Specifically, the detection unit 12 includes a rail 12c for moving the sensor 12a. The rail 12c extends in the X direction. By moving along the rail 12c, the sensor 12a can sequentially detect the flakes conveyed by each of the conveyor sections X1 to X4.

[0048] Position information in the X direction may be transferred from the sensor 12a to the processing unit 12b, linked to the HSI data. In this case, the processing unit 12b can determine which of the conveyor sections X1 to X4 the HSI data corresponds to based on the position information in the X direction.

[0049] In this embodiment as well, based on the detection results of the sensor 12a, the processing unit 12b calculates the composition ratio of the flakes flowing over the transport units X1 to X4. In other words, in this embodiment, the detection unit 12 acquires the recovered material information and raw material information and inputs it to the calculation unit 13. As the detection unit 12 detects the composition ratio of the raw materials in this way, the raw material detection unit 11 shown in Figure 1 may be omitted. However, the raw material detection unit 11 in Figure 1 may detect the specific charge of the raw materials, and the detection unit 12 in Figure 5 may detect the composition ratio of the raw materials.

[0050] As described above, the sorting apparatus 1 according to Embodiment 2 further comprises a raw material transport unit X4 for transporting a portion of the raw material, which is a mixture before sorting. The raw material transport unit X4 is arranged side by side with the first transport unit X1 and the second transport unit X2. The sensor 12a irradiates the raw material transport unit X4 with light and detects the reflected light. The processing unit 12b processes the detection result of the sensor 12a and calculates the composition ratio of each type of plastic piece in the raw material.

[0051] According to this embodiment, the composition ratio of the raw materials can be detected using the sensor 12a for detecting the composition ratio of the recovered material. Therefore, it is possible to reduce the number of sensors compared to the case where only sensors for detecting the composition ratio of the raw materials are used.

[0052] Furthermore, the sensor 12a is movable in the X direction, where the first transport unit X1 and the second transport unit X2 are arranged side by side. Therefore, even if the detection range of the sensor 12a is narrower than the range of arrangement of the first transport unit X1 and the second transport unit X2 in the X direction, the composition ratio of the first and second recovered materials can be detected. In particular, when detecting four transport units X1 to X4 as in this embodiment, the range to be detected becomes wider, so a configuration in which the sensor 12a is movable is preferable.

[0053] The technical scope of this disclosure is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of this disclosure.

[0054] For example, the above embodiment described a case in which plastic pieces are sorted by electrostatic sorting. However, the sorting method is not limited, and for example, it may be specific gravity sorting or optical sorting. Specific gravity sorting is a sorting method that takes advantage of the fact that different types of plastic pieces have different specific gravities. For example, if a group of plastic pieces is vibrated or floated on a medium, the plastic pieces with a higher specific gravity will sink, and the plastic pieces with a lower specific gravity will rise. In this case, the plastic pieces that have sunk can be placed on the first transport unit X1, and the plastic pieces that have risen can be placed on the second transport unit X2.

[0055] Optical sorting is a sorting method that utilizes the fact that different types of plastic pieces have different light reflectivity. In optical sorting, detection light is shone onto a group of plastic pieces, and the reflected light is detected. Various wavelengths of light, such as infrared or X-rays, can be used as detection light. By detecting the spectrum of the reflected light or Raman scattered light, the plastic pieces can be distinguished by type. After this distinction, the plastic pieces may be sorted by air blowing or other methods.

[0056] Furthermore, in the above embodiment 1, one sensor 12a was used to detect the collected materials from the three collection units 127a to 127c. However, one sensor 12a may be used to detect only two of the three collected materials.

[0057] Furthermore, the number of sensors may be two or more, and each sensor may detect two or more collected items. For example, in Embodiment 2, two sensors 12a may be arranged. In this case, the first sensor 12a may target the transport units X1 and X3, and the second sensor 12a may target the transport units X2 and X4. In these modified examples, it is possible to reduce the number of sensors compared to the conventional system.

[0058] Furthermore, the above-described embodiments or modifications may be combined as appropriate. For example, the movable sensor 12a shown in Figure 5 of Embodiment 2 may be used to detect the collected material on the transport units X1 to X3 shown in Figure 2 of Embodiment 1. Alternatively, the sensor 12a shown in Figure 2 of Embodiment 1 may be used to simultaneously scan the four transport units X1 to X4 shown in Figure 5 of Embodiment 2. In this case, the detection range of the sensor 12a in the X direction should span across the transport units X1 to X4.

[0059] 1... Sorting and processing unit 2... Charging unit 3... Electric field generation unit 12a... Sensor 12b... Processing unit 127a... First recovery unit 127a... Recovery unit 127b... Second recovery unit 127b... Recovery unit 127c... Third recovery unit p1-p3... Plastic pieces X1... First transport unit X1... Transport unit X2... Second transport unit X4... Raw material transport unit

Claims

1. A sorting apparatus for sorting a mixture containing multiple types of plastic pieces according to the type of plastic piece, comprising: a first recovery unit for recovering a first recovered material which is a part of the sorted mixture; a second recovery unit for recovering a second recovered material which is a part of the sorted mixture; a first transport unit for transporting the first recovered material from the first recovery unit; a second transport unit arranged alongside the first transport unit for transporting the second recovered material from the second recovery unit; a sensor arranged outside the first and second recovery units for irradiating the first and second transport units with light and detecting reflected light; and a processing unit for processing the detection results from the sensor and calculating the composition ratio of each type of plastic piece in the first and second recovered materials.

2. The sorting apparatus according to claim 1, further comprising a raw material conveying unit for conveying a portion of the raw material which is the mixture before sorting, wherein the raw material conveying unit is arranged in parallel with the first conveying unit and the second conveying unit, the sensor irradiates light onto the raw material conveying unit and detects the reflected light, and the processing unit processes the detection result of the sensor and calculates the composition ratio of each type of plastic piece in the raw material.

3. The sorting apparatus according to claim 1 or 2, further comprising: a third recovery unit disposed between the first recovery unit and the second recovery unit for recovering a third recovered material which is part of the sorted mixture; and a third transport unit disposed between the first transport unit and the second transport unit for transporting the third recovered material from the third recovery unit, wherein the sensor irradiates light onto the third transport unit and detects the reflected light; and the processing unit processes the detection results from the sensor and calculates the composition ratio of each type of plastic piece in the third recovered material.

4. The sorting apparatus according to any one of claims 1 to 3, wherein the sensor is movable in the direction in which the first transport unit and the second transport unit are arranged.

5. The sorting apparatus according to any one of claims 1 to 4, wherein the sensor is a hyperspectral camera.

6. The sorting apparatus according to any one of claims 1 to 5, wherein the processing unit calculates the composition ratio of each type of plastic piece in the first and second recovered materials based on the area ratio of each type of plastic piece contained in the first and second recovered materials.

7. The sorting apparatus according to any one of claims 1 to 6, further comprising: a charging unit for charging the mixture before sorting; and an electric field generating unit for applying an electrostatic field to the charged mixture.

8. A sorting method for sorting a mixture containing multiple types of plastic pieces according to the type of plastic piece, comprising: transporting a first recovered material and a second recovered material, which are part of the sorted mixture, by a first transport unit and a second transport unit arranged side by side; detecting the first recovered material on the first transport unit and the second recovered material on the second transport unit with a single sensor; and calculating the composition ratio of each type of plastic piece in the first recovered material and the second recovered material based on the detection result of the sensor.

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