Plastic detection device and plastic detection program

Abstract

The material of the target plastic is appropriately determined. [Solution] In the plastic determination device, a transmitted light source 18 and a reflected light source 20 irradiate the target plastic 14 with near-infrared light, and a spectroscopic sensor 22 receives the near-infrared light from the target plastic 14 to measure the target spectrum of the target plastic 14. Here, the material of the target plastic 14 is determined to be the reference plastic having the reference transmission spectrum or reference reflection spectrum of the reference plastic that is most similar to the target spectrum of the target plastic 14. Therefore, the material of the target plastic 14 can be determined based on the reference transmission spectrum and reference reflection spectrum, and the material of the target plastic 14 can be appropriately determined.

Description

Technical Field

[0001] The present invention relates to a plastic determination device and a plastic determination program for determining the material of plastic.

Background Art

[0002] In the determination device described in Patent Document 1 below, a light source for transmission measurement irradiates a plastic material from one side, and a light receiving unit receives infrared rays that have passed through the plastic material, as well as infrared rays that are irradiated onto the plastic material from the other side by a light source for reflection measurement and reflected by the plastic material.

[0003] Here, it is understood that in this determination device, the absorption spectrum of the infrared rays received by the light receiving unit is compared with reference spectra of various plastics to determine the material of the plastic material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In consideration of the above facts, the present invention aims to obtain a plastic determination device and a plastic determination program that can appropriately determine the material of a target plastic.

Means for Solving the Problems

[0006] A plastic determination device according to a first aspect of the present invention includes: a storage unit that stores a reference transmission spectrum, which is the spectrum of infrared radiation transmitted through a reference plastic and partially absorbed by the reference plastic, and a reference reflection spectrum, which is the spectrum of infrared radiation reflected by a reference plastic and partially absorbed by the reference plastic, for a plurality of reference plastics having different materials; a transmission irradiation unit that irradiates the target plastic with infrared radiation from one side; a reflection irradiation unit that irradiates the target plastic with infrared radiation from the other side; a light receiving unit arranged on the other side of the target plastic and capable of receiving infrared radiation irradiated by the transmission irradiation unit and transmitted through the target plastic and infrared radiation irradiated by the reflection irradiation unit and reflected by the target plastic; and a determination unit that determines the material of the target plastic to be the material of the reference plastic having a reference transmission spectrum or reference reflection spectrum that is most similar to the target spectrum, which is the spectrum of infrared radiation received by the light receiving unit.

[0007] A second aspect of the present invention is a plastic determination device in which, in the first aspect of the present invention, the transmission irradiation unit irradiates the target plastic with infrared rays from one side, and at the same time, the reflection irradiation unit irradiates the target plastic with infrared rays from the other side.

[0008] A third aspect of the present invention is a plastic determination device in the first or second aspect of the present invention, wherein the determination unit determines the material of the reference plastic to be the material of the target plastic if either the similarity of the target spectrum to a reference transmission spectrum or the similarity of the target spectrum to a reference reflectance spectrum is less than or equal to a determination threshold, and the similarity of the reference transmission spectrum and the reference reflectance spectrum exceeds the determination threshold.

[0009] A fourth aspect of the present invention is a plastic determination device in any one of the first to third aspects of the present invention, wherein the determination unit determines that the material of the target plastic is unknown when the similarity of the target spectrum to a reference transmission spectrum and the similarity of the target spectrum to a reference reflectance spectrum are less than or equal to a determination threshold.

[0010] A fifth aspect of the present invention provides a plastic determination program that causes a computer to perform the following steps: store a reference transmission spectrum, which is the spectrum of infrared radiation transmitted through a reference plastic and partially absorbed by the reference plastic, and a reference reflection spectrum, which is the spectrum of infrared radiation reflected by the reference plastic and partially absorbed by the reference plastic, for a plurality of reference plastics having different materials; irradiate the target plastic with infrared radiation from one side and irradiate the target plastic with infrared radiation from the other side, so that the light receiving unit receives infrared radiation irradiated to the target plastic from one side and transmitted through the target plastic or infrared radiation irradiated to the target plastic from the other side and reflected by the target plastic; and determine that the material of the reference plastic having the reference transmission spectrum or reference reflection spectrum most similar to the target spectrum, which is the spectrum of infrared radiation received by the light receiving unit, is the material of the target plastic. [Effects of the Invention]

[0011] In the plastic determination device according to the first aspect of the present invention, for a plurality of reference plastics having different materials, a reference transmission spectrum, which is the spectrum of infrared radiation transmitted through the reference plastic and partially absorbed by the reference plastic, and a reference reflection spectrum, which is the spectrum of infrared radiation reflected by the reference plastic and partially absorbed by the reference plastic, are stored in the storage unit.

[0012] Furthermore, the transmitting irradiation unit irradiates the target plastic with infrared light from one side, while the reflecting irradiation unit irradiates the target plastic with infrared light from the other side. In addition, a light receiving unit is positioned on the other side of the target plastic, enabling the light receiving unit to receive infrared light that has been irradiated by the transmitting irradiation unit and passed through the target plastic, as well as infrared light that has been irradiated by the reflecting irradiation unit and reflected by the target plastic. Therefore, if the target plastic is an infrared-transmitting plastic, the light receiving unit receives the infrared light that has been passed through the target plastic, and if the target plastic is an infrared-impermeable plastic, the light receiving unit receives the infrared light that has been reflected by the target plastic.

[0013] Here, the detection unit determines the material of the target plastic to be the reference plastic material that has a reference transmission spectrum or reference reflection spectrum that is most similar to the target spectrum, which is the infrared spectrum received by the light receiving unit. Therefore, the material of the target plastic can be determined based on the reference transmission spectrum and reference reflection spectrum, and the material of the target plastic can be appropriately determined.

[0014] In the plastic determination device according to the second aspect of the present invention, a transmission irradiation unit irradiates the target plastic with infrared light from one side, while a reflection irradiation unit irradiates the target plastic with infrared light from the other side. This reduces the time required to determine the material of the target plastic.

[0015] In the plastic determination device of the third aspect of the present invention, if either the similarity of the target spectrum to a reference transmission spectrum or the similarity of the target spectrum to a reference reflectance spectrum is below a determination threshold, the determination unit determines that the material of the reference plastic whose similarity exceeds the determination threshold is the material of the target plastic. Therefore, the material of the target plastic can be determined appropriately.

[0016] In the plastic determination device of the fourth aspect of the present invention, the determination unit determines that the material of the target plastic is unknown when the similarity of the target spectrum to a reference transmission spectrum and the similarity of the target spectrum to a reference reflectance spectrum are below a determination threshold. Therefore, the material of the target plastic can be determined appropriately.

[0017] In the fifth aspect of the present invention, a plastic determination program stores, for a plurality of reference plastics of different materials, a reference transmission spectrum, which is the spectrum of infrared radiation transmitted through the reference plastic and partially absorbed by the reference plastic, and a reference reflection spectrum, which is the spectrum of infrared radiation reflected by the reference plastic and partially absorbed by the reference plastic.

[0018] Further, by irradiating the target plastic with infrared light from one side and irradiating the target plastic with infrared light from the other side, the light receiving unit receives the infrared light that is irradiated to the target plastic from one side and transmitted through the target plastic when the target plastic is an infrared transmitting plastic, or the infrared light that is irradiated to the target plastic from the other side and reflected by the target plastic when the target plastic is an infrared non-transmitting plastic.

[0019] Here, the material of the reference plastic having the reference transmission spectrum or the reference reflection spectrum that is most similar to the target spectrum, which is the spectrum of the infrared light received by the light receiving unit, is determined as the material of the target plastic. Therefore, the material of the target plastic can be determined based on the reference transmission spectrum and the reference reflection spectrum, and the material of the target plastic can be appropriately determined. Brief Description of the Drawings

[0020] [Figure 1] FIG. 2 is a perspective view showing the plastic sorting device according to the embodiment of the present invention, as viewed from the diagonally front right side. [Figure 2] FIG. 3 is a perspective view showing the plastic determination device of the plastic sorting device, as viewed from the diagonally front right side. [Figure 3] FIG. 4 is a cross-sectional view showing the main part of the plastic determination device, as viewed from the front side. [Figure 4] FIG. 5 is a cross-sectional view showing the spectroscopic sensor and the like of the plastic determination device, as viewed from the front side. [Figure 5] FIG. 6 is a block diagram showing the hardware configuration of the plastic determination device. [Figure 6] FIG. 7 is a block diagram showing an example of the functional configuration of the plastic determination device. [Figure 7] FIG. 8 is a spectroscopic spectrum diagram showing the measurement range of near-infrared spectra in the plastic determination device. [Figure 8] FIG. 9 is a procedure diagram showing the plastic determination processing in the plastic determination device. [Figure 9] FIG. 10 is a first flowchart showing the plastic determination processing. [Figure 10] This is the second flowchart showing the plastic determination processing. [Figure 11] This is the third flowchart showing the plastic determination processing. DETAILED DESCRIPTION OF EMBODIMENTS

[0021] FIG. 1 shows the plastic sorting apparatus 12 according to the embodiment of the present invention in a perspective view as seen from the diagonally upper right front, and FIG. 2 shows the plastic determination apparatus 10 of the plastic sorting apparatus 12 in a perspective view as seen from the diagonally upper right front. In the drawings, the front of the plastic sorting apparatus 12 is indicated by arrow FR, the right side of the plastic sorting apparatus 12 is indicated by arrow RH, and the upper side of the plastic sorting apparatus 12 is indicated by arrow UP.

[0022] As shown in FIG. 1, the plastic sorting apparatus 12 in the present embodiment is provided with the plastic determination apparatus 10 (see FIG. 2). An apparatus main body 10A having a substantially U-shaped cross section is provided at the upper portion of the plastic determination apparatus 10, and the inner side of the apparatus main body 10A is open to the front, left, and right. Inside the apparatus main body 10A (near the upper side of the lower part of the apparatus main body 10A), the target plastic 14 is conveyed from the left side to the right side as described later.

[0023] A measurement unit 16 (see FIG. 3) is provided inside the apparatus main body 10A.

[0024] A transmission light source 18 is fixed inside the upper part of the main body 10A as a transmission irradiation unit. The transmission light source 18 is a halogen lamp that irradiates near-infrared light to the lower part of the upper part of the main body 10A. A cylindrical first irradiation tube 18A made of metal is fixed below the transmission light source 18. The transmission light source 18 irradiates near-infrared light downwards through the first irradiation tube 18A, and the direction of irradiation of the near-infrared light is controlled by the first irradiation tube 18A. If the target plastic 14 is a near-infrared transparent plastic (transparent or thin-walled opaque plastic), the near-infrared light from the transmission light source 18 is transmitted downwards through the target plastic 14. If the target plastic 14 is a near-infrared impermeable plastic (thick-walled opaque plastic), the near-infrared light from the transmission light source 18 is reflected upwards by the target plastic 14.

[0025] Inside the lower part of the main body 10A of the device, reflective light sources 20 (see Figure 4) are fixed to the left and right of the transmitted light source 18, serving as reflective irradiation units. The reflective light sources 20 are halogen lamps that irradiate near-infrared light upwards and toward the transmitted light source 18. A cylindrical second irradiation tube 20A made of metal is fixed above the reflective light sources 20. The reflective light sources 20 irradiate near-infrared light through the second irradiation tube 20A in a direction that moves upwards toward the transmitted light source 18, and the irradiation direction of the near-infrared light is controlled by the second irradiation tube 20A. If the target plastic 14 is a near-infrared transparent plastic, the near-infrared light from the reflective light sources 20 is transmitted upwards through the target plastic 14. If the target plastic 14 is a near-infrared opaque plastic, the near-infrared light from the reflective light sources 20 is reflected downwards by the target plastic 14. Note that only one of the left reflective light source 20 and second irradiation tube 20A or the right reflective light source 20 and second irradiation tube 20A may be provided.

[0026] A spectroscopic sensor 22 (NIR (Near InfraRed) sensor) is fixed inside the lower part of the main body 10A, below the transmitted light source 18 and in the center between the second irradiation tubes 20A, and the spectroscopic sensor 22 receives (measures) near-infrared light from above. Therefore, the spectroscopic sensor 22 receives near-infrared light that has been transmitted downwards by the transmitted light source 18 and passed through the target plastic 14 (near-infrared transparent plastic), and near-infrared light that has been reflected downwards by the target plastic 14 (near-infrared opaque plastic) irradiated by the reflected light source 20. A cylindrical metal light receiving tube 22A is fixed above the spectroscopic sensor 22, and the inside of the light receiving tube 22A is open to the top. The light receiving tube 22A surrounds the light receiving range of the spectroscopic sensor 22, and by receiving near-infrared light that has been diffusely reflected and averaged within the light receiving tube 22A, the spectroscopic sensor 22 is able to receive stable near-infrared light over a wider range than its normal receiving range. The upper end of the light-receiving tube 22A is positioned above the upper end of the second irradiation tube 20A, and the light-receiving tube 22A suppresses the detection of stray light by the spectral sensor 22.

[0027] Fiber sensors 24 are fixed to the left and right vicinity of the spectral sensor 22 as object sensors. The fiber sensors 24 detect the target plastic 14, which is positioned above it, by emitting and receiving light onto the target plastic 14.

[0028] The upper lower wall of the main body 10A of the device is composed of a transparent glass transmissive plate 26 above the reflective light source 20, the second irradiation tube 20A, the spectroscopic sensor 22, and the light receiving tube 22A. The transmissive plate 26 allows the near-infrared light that has been irradiated by the transmissive light source 18 and transmitted downwards through the target plastic 14 (near-infrared transparent plastic), the near-infrared light that has been irradiated upwards by the reflective light source 20, and the near-infrared light that has been irradiated by the reflective light source 20 and reflected downwards by the target plastic 14 (near-infrared opaque plastic) to pass through. A through hole 26A is formed through the transmissive plate 26 above the fiber sensor 24, and the light emitted and received by the fiber sensor 24 passes through the through hole 26A.

[0029] As described above, the measurement unit 16 measures the spectrum of near-infrared light partially absorbed by the target plastic 14 by receiving near-infrared light partially absorbed by the target plastic 14 with the spectral sensor 22.

[0030] A display panel 30, which constitutes the notification unit 28, is provided on the front of the middle section (upper and lower middle section) of the main body 10A of the device, and the front of the display panel 30 is capable of displaying images. An indicator light 32 (see Figure 2), which constitutes the notification unit 28, is provided inside the front end of the upper part of the main body 10A, and the indicator light 32 is a full-color LED. The indicator light 32 is capable of emitting light from the lower part of the upper part of the main body 10A, and its emission color can be changed.

[0031] As shown in Figure 5, the plastic detection device 10 includes a CPU 34 (Central Processing Unit: processor), ROM 36 (Read Only Memory), RAM 38 (Random Access Memory), storage 40, user interface 42, notification unit 28, and measurement unit 16. Each component is connected to the others via a bus 44 so as to be able to communicate with each other.

[0032] The CPU 34 is a central processing unit that executes various programs and controls various parts. Specifically, the CPU 34 reads a program from the ROM 36 or storage 40 and executes the program using the RAM 38 as a working area. The CPU 34 controls each of the above components and performs various calculations according to the program recorded in the ROM 36 or storage 40. In this embodiment, the ROM 36 or storage 40 stores a plastic determination program that determines the material of the target plastic 14.

[0033] ROM36 ​​stores various programs and data. RAM38 temporarily stores programs or data as a working area. Storage40 consists of an HDD (Hard Disk Drive) or SSD (Solid State Drive) and stores various programs and data.

[0034] The user interface 42 is the interface used by the user when using the plastic detection device 10. The user interface 42 includes, for example, a power button 46 (see Figure 2) that the user can press. The notification unit 28 notifies the user using the plastic detection device 10, for example, by displaying information on the display panel 30 and illuminating the indicator light 32.

[0035] When executing the plastic detection program described above, the plastic detection device 10 uses the hardware resources described above to implement various functions. The functional configuration implemented by the plastic detection device 10 will now be described.

[0036] As shown in Figure 6, the plastic detection device 10 has a functional configuration consisting of a measurement unit 16, a storage unit 48, a detection unit 50, and a notification unit 28. Each functional configuration is realized when the CPU 34 reads a plastic detection program stored in the ROM 36 or storage 40, loads it into the RAM 38, and executes it.

[0037] The memory unit 48 has a pre-stored (set) near-infrared wavelength range (determination wavelength range, in this embodiment 1670 nm to 1790 nm) used to determine the material of the target plastic 14 (see Figure 7).

[0038] The memory unit 48 stores the reference value and dark value (transmission reference value and dark value) for transmitted near-infrared light received by the spectroscopic sensor 22 in the measurement unit 16, and the reference value and dark value (reflection reference value and dark value) for reflected near-infrared light received by the spectroscopic sensor 22 in the measurement unit 16. Note that the transmission dark value and the reflection dark value are the same.

[0039] In the memory unit 48, the reference transmission spectrum, which is the spectrum of near-infrared light transmitted through the reference plastic and partially absorbed by the reference plastic, is pre-stored in the transmission library 48A, and the reference reflection spectrum, which is the spectrum of near-infrared light reflected by the reference plastic and partially absorbed by the reference plastic, is pre-stored in the reflection library 48B, with the reference plastics being PP, PE, PVC, PS, ABS, PET, PMMA, and PC (see Figure 10). The reference transmission spectrum stored in the transmission library 48A is reference transmission data obtained by taking the second derivative of the absorbance of the reference plastic at transmission, calculated using the reference value and Dark value of transmission in the determination wavelength range. The reference reflection spectrum stored in the reflection library 48B is reference reflection data obtained by taking the second derivative of the absorbance of the reference plastic at reflection, calculated using the reference value and Dark value of transmission in the determination wavelength range.

[0040] The memory unit 48 pre-stores the following threshold values ​​for near-infrared intensity (light quantity) necessary for determining the material of the target plastic 14 (intensity threshold), and the following threshold values ​​for the correlation coefficient (determination threshold) for determining the material of the target plastic 14.

[0041] The determination unit 50 determines the material of the target plastic 14 based on the target spectrum, which is the near-infrared spectrum partially absorbed by the target plastic 14 as received by the spectroscopic sensor 22. In other words, the determination unit 50 determines that the material of the target plastic 14 is the reference plastic having the reference transmission spectrum or reference reflection spectrum that is most similar to the target spectrum.

[0042] The notification unit 28 displays the material of the target plastic 14 determined by the determination unit 50 on the display panel 30.

[0043] Inside the main body 10A of the plastic detection device 10 (near the upper part of the lower part of the main body 10A), the belt 52A of the conveying mechanism, the belt 52A, is arranged (see Figure 1). The belt 52A extends to the left and right of the main body 10A and is made of, for example, a metal mesh to allow light to pass through. When the belt conveyor 52 is operated, the belt 52A moves from the left side to the right side of the main body 10A. Therefore, when the target plastic 14 is placed on the belt 52A on the left side of the main body 10A, the target plastic 14 is moved to the right side by the belt 52A.

[0044] A sorting mechanism 54 is provided on the right side of the main body 10A of the device, and multiple sorting boxes 56 are provided behind the sorting mechanism 54. At least one sorting box 56 is provided for each material of the target plastic 14, and the multiple sorting boxes 56 are arranged in the left-right direction. The sorting mechanism 54 is made possible by supplying the target plastic 14 on the belt 52A to the sorting box 56 corresponding to the material of the target plastic 14 determined by the determination unit 50, thereby sorting the target plastic 14 by material.

[0045] Next, the operation of this embodiment will be explained.

[0046] In the plastic detection device 10 configured as described above, the belt conveyor 52 is operated, and the belt 52A moves from left to right, causing the target plastic 14 on the belt 52A to move from left to right inside the main body 10A of the plastic detection device 10.

[0047] In the determination unit 50 of the plastic determination device 10, plastic determination processing (see Figures 8 to 11) is performed. Plastic determination processing is performed by the CPU 34 reading a plastic determination program from the ROM 36 or storage 40, loading it into the RAM 38, and executing it.

[0048] In the plastic detection process, in step 100, a pair of fiber sensors 24 of the measuring unit 16 project light upwards, and in step 102, it is determined whether the pair of fiber sensors 24 have detected (turned ON) the target plastic 14 above. If the determination in step 102 is negative, the process returns to step 100.

[0049] If the determination in step 102 is affirmed, in step 104 the measurement unit 16 performs the measurement process. That is, the transmitting light source 18 irradiates the lower target plastic 14 with near-infrared light, and at the same time, the reflecting light source 20 irradiates the upper target plastic 14 with near-infrared light. If the target plastic 14 is a near-infrared transmitting plastic, the near-infrared light from the transmitting light source 18 is transmitted downwards through the target plastic 14, and if the target plastic 14 is a near-infrared non-transparent plastic, the near-infrared light from the reflecting light source 20 is reflected downwards by the target plastic 14. Furthermore, in step 106, the spectroscopic sensor 22 receives the near-infrared light from the target plastic 14, and the spectrum of the near-infrared light partially absorbed by the target plastic 14 (target spectrum) is measured (acquired).

[0050] Then, in step 108, the intensity (light quantity) of the near-infrared light received by the spectroscopic sensor 22 is determined for each wavelength of near-infrared light, and in step 110, it is determined whether or not there is a wavelength of near-infrared light whose intensity received by the spectroscopic sensor 22 is below the threshold (intensity threshold) of near-infrared light intensity necessary to determine the material of the target plastic 14.

[0051] If the determination in step 110 is affirmed, in step 112, "Insufficient Light Intensity" is displayed on the display panel 30 of the notification unit 28. This informs the user that the near-infrared irradiation intensity to the target plastic 14 is insufficient. Then, in step 114, it is determined whether the pair of fiber sensors 24 do not detect the target plastic 14 above (turned OFF). If the determination in step 114 is affirmed, the process returns to step 100; if the determination in step 114 is denied, the process returns to step 112.

[0052] If the judgment in step 110 is rejected, in step 116 the reference and dark values ​​for transmission and the reference and dark values ​​for reflection are trimmed within the judgment wavelength range, and in step 118 the transmission measurement judgment is performed, and at the same time in step 120 the reflection measurement judgment is performed.

[0053] In step 118, the transmission measurement determination is performed. In step 122, the absorbance of the target plastic 14 is calculated using the Reference and Dark values ​​of the transmission within the determination wavelength range for the target spectrum from step 106. In step 124, the target transmission data (second derivative value of transmission) is calculated by taking the second derivative of the absorbance of the target plastic 14. Then, in step 126, the correlation coefficient (so-called Pearson product-moment correlation coefficient, similarity) is calculated between the target transmission data of the target spectrum and the reference transmission data of each reference transmission spectrum in the transmission library 48A. In step 128, the reference plastics of the reference transmission data are sorted in descending order of correlation coefficient. In step 130, the names (resin names) and correlation coefficients of the top three reference plastics are displayed on the display panel 30.

[0054] In the reflectance measurement determination in step 120, in step 132, the absorbance of the target plastic 14 in the reflected state is calculated using the reference value and dark value of the reflectance within the determination wavelength range for the target spectrum in step 106. In step 134, the target reflectance data (second derivative value of the reflectance) is calculated by taking the second derivative of the absorbance of the target plastic 14 in the reflected state. Then, in step 136, the correlation coefficient between the target reflectance data of the target spectrum and the reference reflectance data of each reference reflectance spectrum in the reflectance library 48B is calculated. In step 138, the reference plastics of the reference reflectance data are sorted in descending order of correlation coefficient, and in step 140, the names and correlation coefficients of the top three reference plastics are displayed on the display panel 30.

[0055] Following steps 130 and 140, in step 142 a superiority determination is made, and in step 144 it is determined whether the highest correlation coefficient of the reference transmission data in step 126 and the highest correlation coefficient of the reference reflection data in step 136 are less than or equal to a correlation coefficient threshold (determination threshold, e.g., 70) for determining the material of the target plastic 14.

[0056] In step 144, if the highest correlation coefficient of the reference transmission data and the highest correlation coefficient of the reference reflection data exceed the determination threshold, the material of the target plastic 14 is determined to be the material of the reference plastic with the larger correlation coefficient between the highest correlation coefficient of the reference transmission data and the highest correlation coefficient of the reference reflection data, and in step 146, the name of the reference plastic is displayed on the display panel 30 as the material of the target plastic 14.

[0057] In step 144, if either the highest correlation coefficient of the reference transmission data or the highest correlation coefficient of the reference reflection data is below the judgment threshold, the material of the target plastic 14 is determined to be the material of the reference plastic whose correlation coefficient between the highest correlation coefficient of the reference transmission data and the highest correlation coefficient of the reference reflection data exceeds the judgment threshold, and in step 148, the name of the reference plastic is displayed on the display panel 30 as the material of the target plastic 14.

[0058] In step 144, if the highest correlation coefficient of the reference transmission data and the highest correlation coefficient of the reference reflection data are below the judgment threshold, the material of the target plastic 14 is determined to be unknown, and in step 150, "Unknown" is displayed on the display panel 30 for the material of the target plastic 14.

[0059] After steps 146, 148, and 150, return to step 100.

[0060] After the determination unit 50 of the plastic determination device 10 determines the material of the target plastic 14, the sorting mechanism 54 supplies the target plastic 14 on the belt 52A to the sorting box 56 corresponding to the material of the target plastic 14 determined by the determination unit 50, and the target plastic 14 is sorted by material.

[0061] In this case, the plastic determination device 10 determines that the material of the reference plastic having the reference transmission spectrum (reference transmission data) or reference reflection spectrum (reference transmission data) of the reference plastic that is most similar to the target spectrum (target transmission data or target reflection data) of the target plastic 14 is the material of the target plastic 14. Therefore, the material of the target plastic 14 can be determined based on the reference transmission spectrum and reference reflection spectrum, and the material of the target plastic 14 can be appropriately determined.

[0062] Furthermore, if either the similarity (correlation coefficient) of the target spectrum to the reference transmission spectrum or the similarity (correlation coefficient) of the target spectrum to the reference reflection spectrum is below a judgment threshold, the judgment unit 50 determines that the material of the reference plastic whose similarity to the reference transmission spectrum exceeds the judgment threshold is the material of the target plastic 14. This allows for an appropriate determination of the material of the target plastic 14.

[0063] Furthermore, if the similarity of the target spectrum to the reference transmission spectrum and the similarity of the target spectrum to the reference reflection spectrum are below a judgment threshold, the judgment unit 50 determines that the material of the target plastic 14 is unknown. This allows the user to be notified that the material of the target plastic 14 is not one of the materials of the reference plastics stored in the storage unit 48, and enables an appropriate determination of the material of the target plastic 14.

[0064] Furthermore, the wavelength range of near-infrared light used to determine the material of the target plastic 14 (determination wavelength range) has been narrowed to between 1670 nm and 1790 nm. As a result, the time required for plastic determination processing can be shortened, and the time required to determine the material of the target plastic 14 can be reduced.

[0065] Furthermore, in the measurement unit 16 of the plastic determination device 10, the transmitted light source 18 irradiates the target plastic 14 with near-infrared light from above, while the reflected light source 20 irradiates the target plastic 14 with near-infrared light from below. If the target plastic 14 is a near-infrared transmitting plastic, the near-infrared light from the transmitted light source 18 is transmitted downwards through the target plastic 14, and the near-infrared light from the reflected light source 20 is transmitted upwards through the target plastic 14. On the other hand, if the target plastic 14 is a near-infrared opaque plastic, the near-infrared light from the transmitted light source 18 is reflected upwards by the target plastic 14, and the near-infrared light from the reflected light source 20 is reflected downwards by the target plastic 14. Therefore, in both cases, whether the target plastic 14 is a near-infrared transmitting plastic or a near-infrared opaque plastic, the spectral sensor 22 on the lower side of the target plastic 14 can receive transmitted or reflected near-infrared light onto the target plastic 14, shortening the time required to measure the target spectrum of the target plastic 14 and thus shortening the time required to determine the material of the target plastic 14. Furthermore, the transmitted light source 18, the reflected light source 20, and the spectral sensor 22 can be arranged in a space-saving manner, and the spectral sensor 22 can be reduced to a single unit, allowing the plastic detection device 10 to be miniaturized and made inexpensive.

[0066] Furthermore, in the measurement unit 16, when the fiber sensors 24 on the left and right sides of the spectroscopic sensor 22 detect the target plastic 14 above, the transmitted light source 18 and the reflected light source 20 irradiate the target plastic 14 with near-infrared light. As a result, near-infrared light can be reliably irradiated onto the target plastic 14, and the target spectrum of the target plastic 14 can be reliably measured.

[0067] In this embodiment, the result of determining the material of the target plastic 14 is notified to the user by displaying the name of the reference plastic on the display panel 30. However, the result of determining the material of the target plastic 14 may also be notified to the user by displaying a word, character (e.g., English letters or numbers) or color set for the reference plastic on the display panel 30, or by illuminating the indicator light 32 in the color set for the reference plastic.

[0068] Furthermore, in this embodiment, a belt conveyor 52, a sorting mechanism 54, and a sorting box 56 are provided around the plastic determination device 10. However, the belt conveyor 52, sorting mechanism 54, and sorting box 56 do not necessarily have to be provided around the plastic determination device 10. In this case, the material of the target plastic 14 can be determined by the user manually placing the target plastic 14 inside the device body 10A of the plastic determination device 10.

[0069] In this embodiment, the CPU 34 reads and executes the plastic detection process using software (program). However, the plastic detection process may be executed by various processors other than the CPU. Examples of such processors include dedicated electrical circuits, which are processors with circuit configurations specifically designed to perform particular processing, such as FPGAs (Field-Programmable Gate Arrays), PLDs (Programmable Logic Devices) whose circuit configurations can be changed after manufacturing, and ASICs (Application Specific Integrated Circuits). The plastic detection process may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is an electrical circuit that combines circuit elements such as semiconductor elements.

[0070] Furthermore, in this embodiment, the plastic detection program is pre-stored (installed) in ROM 36 or storage 40, but is not limited to this. The program may be provided in the form of a recording medium such as CD-ROM (Compact Disk Read Only Memory), DVD-ROM (Digital Versatile Disk Read Only Memory), or USB (Universal Serial Bus) memory. Alternatively, the program may be provided in the form of a download from an external device via a network. [Explanation of symbols]

[0071] 10 Plastic detection device 14 Target Plastics 18 Transmitted light source (transmitted irradiation part) 20 Reflected light source (reflected irradiation part) 22. Spectroscopic sensor (light receiving part) 48 Memory section 50 Judgment section

Claims

1. A storage unit that stores, for multiple reference plastics of different materials, the reference transmission spectrum, which is the spectrum of infrared radiation transmitted through the reference plastic and partially absorbed by the reference plastic, and the reference reflection spectrum, which is the spectrum of infrared radiation reflected by the reference plastic and partially absorbed by the reference plastic, A transmission irradiation unit that irradiates the target plastic with infrared light from one side, A reflective irradiation unit that irradiates the target plastic with infrared light from the other side, A light receiving unit is positioned on the other side of the target plastic and is capable of receiving infrared rays that have been transmitted through the target plastic by the transmission irradiation unit and infrared rays that have been reflected by the target plastic by the reflection irradiation unit. A determination unit that, based on the target spectrum which is the infrared spectrum received by the light receiving unit, refers to the storage unit and calculates the similarity between the target spectrum and each reference transmission spectrum stored in the storage unit, and the similarity between the target spectrum and each reference reflection spectrum stored in the storage unit, and determines that the material of the reference plastic corresponding to the highest similarity among the calculated similarities is the material of the target plastic, A plastic detection device equipped with the following features.

2. The plastic determination device according to claim 1, wherein the transmitting irradiation unit irradiates the target plastic with infrared rays from one side, and at the same time, the reflecting irradiation unit irradiates the target plastic with infrared rays from the other side.

3. The plastic determination device according to claim 1, wherein the determination unit determines that the material of the reference plastic whose similarity between the reference transmission spectrum and the reference reflection spectrum exceeds the determination threshold is the material of the target plastic when either the similarity between the target spectrum and the reference transmission spectrum or the similarity between the target spectrum and the reference reflection spectrum is less than or equal to a determination threshold.

4. The plastic determination device according to claim 1, wherein the determination unit determines that the material of the target plastic is unknown when the similarity of the target spectrum to a reference transmission spectrum and the similarity of the target spectrum to a reference reflectance spectrum are less than or equal to a determination threshold.

5. The steps include storing in a memory unit the reference transmission spectrum, which is the spectrum of infrared radiation transmitted through the reference plastic and partially absorbed by the reference plastic, and the reference reflection spectrum, which is the spectrum of infrared radiation reflected by the reference plastic and partially absorbed by the reference plastic, for multiple reference plastics of different materials. The process involves irradiating the target plastic with infrared light from one side and irradiating the target plastic with infrared light from the other side, so that the light receiving unit receives the infrared light that has been irradiated to the target plastic from one side and passed through the target plastic, or the infrared light that has been irradiated to the target plastic from the other side and reflected by the target plastic. The steps include: referring to the storage unit based on the target spectrum, which is the infrared spectrum received by the light receiving unit, calculating the similarity between the target spectrum and each reference transmission spectrum stored in the storage unit, and the similarity between the target spectrum and each reference reflection spectrum stored in the storage unit, and determining that the material of the reference plastic having the most similar reference transmission spectrum or reference reflection spectrum among the calculated similarities is the material of the target plastic; A plastic detection program to be executed by a computer.

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