JP2014098555A - Recycle resin determination system and manufacturing apparatus of recycled resin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a desired transparent resin.SOLUTION: A recycle resin determination system includes: a conveyer path for conveying objects of transparent resin to be determined; an infrared light source that irradiates a beam of infrared light to the objects to be determined; an infrared light receiving section that receives the reflected infrared light from the objects to be determined which are irradiated with the infrared light; an absorption spectrum calculation section that calculates absorption spectrum of the object to be determined from the reflected infrared light; a measurement section that measures the thickness of the objects to be determined; a storage previously storing a reference data of plural kinds of recycle resin on the basis of thickness of the recycle resin; and a determination section that selects a reference data on the recycle resin of thickness corresponding to the measurement thickness in the reference data as a selection reference data and determines whether the objects to be determined are the recycle resin based on the selection reference data and the absorption spectrum.

Description

  The present invention relates to a recycled resin determination device that determines whether or not an object to be determined is a resin to be recycled, and an apparatus for manufacturing a recycled resin material using the object to be determined that is determined to be a resin to be recycled. .

  Environmental problems such as global warming and resource depletion are now occurring due to mass production, mass consumption, and mass disposal economic activities. In this situation, the recycling of used air conditioners, televisions, refrigerators, freezers, washing machines, etc. has been fully implemented in Japan since April 2001 with the aim of building a resource recycling society. Is required. For this reason, household appliances that are no longer needed are collected separately for each material and recycled at a household appliance recycling factory.

  There are roughly two methods of separating resin materials used in home appliances: human methods and mechanical methods.

  The human method is a method of recovering a resin to be recycled (hereinafter referred to as a recycled resin) by manually disassembling and removing a single material part that can be visually selected by a person. With this human method, it is not possible to distinguish anything other than what can visually confirm the type of resin, such as display of the resin type. Therefore, the remainder of the resin material that could not be sorted by humans is crushed and made into a mixture containing a plurality of types of plastics called mixed plastics. A mechanical method is applied as a method for determining and selecting a recycled resin from the mixed plastic.

  As a kind of mechanical method, a specific gravity sorting method using water is known. The specific gravity sorting method is a method in which, for example, a mixed plastic containing polypropylene (hereinafter referred to as PP) is poured into water, and only a resin material floating on the water surface is determined and recovered as PP. Since PP is a light specific gravity material, it has the property of floating in water. For this reason, it can be determined by a specific gravity sorting method. However, in the specific gravity sorting method, a large amount of wastewater is generated, and between PP and polystyrene (hereinafter referred to as PS), acrylonitrile / butadiene / styrene (hereinafter referred to as ABS), etc., which have a specific gravity close to PP. The problem is that it is not possible to accurately determine and sort the above.

  Therefore, Patent Document 1 discloses a technique for determining only a recycled resin, for example, PP from a mixed plastic in which a plurality of resins such as PP, PS, and ABS are mixed without using water. A conventional technique will be described with reference to FIG.

  The recycled resin determination device 1 according to the related art irradiates infrared light from the surface of the determination object 3 by irradiating the surface of the determination object 3 conveyed by the conveyance path 2 with infrared light from the light source 4. (Hereinafter referred to as infrared reflected light) is reflected. The infrared reflected light reflected from the surface of the determination object 3 is imaged by the light receiving unit 7 via the mirror 5 and the polygon mirror 6. At this time, the control device 8 compares the feature quantity of the infrared reflected light imaged by the light receiving unit 7 with the preset feature quantity of the recycled resin. As a result of comparison by the control device 8, when the feature amount of the determination target object 3 matches a preset feature amount of the recycled resin, the determination target component 3 is determined as the recycled resin. In this way, the recycled resin determination device 1 according to the related art determines, for example, only PP as the recycled resin from the mixed plastic that is the determination target 3.

Japanese translation of PCT publication No. 2002-540397

  However, when the object to be determined is a transparent resin, in the conventional technology, infrared reflected light from the conveyance path located below the object to be determined is also imaged together. In this case, the feature amount of the determination target acquired based on the captured reflected light is acquired as the feature amount of the transport path overlapped as noise.

  It is impossible to determine whether or not the type of the object to be determined is a recycled resin using such a feature amount including the influence of noise.

  That is, in the related art, when the determination target is a transparent resin, there is a problem that it cannot be determined whether or not the determination target is a recycled resin.

  Therefore, an object of the present invention is to solve the above-described problems and to determine whether or not a determination target object that is a transparent resin is a resin to be recycled.

  In order to solve the above-described problems, a recycled resin determination device according to the present invention includes a conveyance path for conveying a determination object that is a transparent resin, an infrared light source that irradiates the determination object with infrared light, and the red An infrared light receiving unit that receives infrared reflected light from the object to be determined irradiated with external light, an absorption spectrum calculating unit that calculates an absorption spectrum of the object to be determined from the infrared reflected light, and the object to be determined A measurement unit for measuring a measurement thickness that is a thickness of the storage unit, a storage unit in which a plurality of types of recycled resin reference data is stored in advance for each thickness of the recycled resin, and the thickness of the reference data corresponding to the measured thickness A determination unit that selects reference data in the recycled resin as selection reference data, and determines whether the determination object is the recycled resin based on the selection reference data and the absorption spectrum; It is characterized in.

  According to the present invention, it is possible to determine whether a transparent resin is a resin to be recycled.

Schematic diagram of recycled resin determination device according to Embodiment 1 Schematic diagram of a detection unit according to Embodiment 1. The figure which showed the graph of the absorption spectrum of the to-be-determined object of different thickness detected with the detection unit which concerns on Embodiment 1. The block diagram which showed the memory | storage part with which the arithmetic processing part which concerns on Embodiment 1 is provided, and the determination part The flowchart which shows the operation | movement of the determination by the determination part which concerns on Embodiment 1. FIG. The figure which shows the graph of the absorption spectrum which subtracted the noise detected when thickness is 2 mm and 3 mm from the absorption spectrum of the to-be-determined object whose thickness is 1 mm The figure which shows the graph of the absorption spectrum which subtracted the noise detected when the thickness is 1 mm from the absorption spectrum of the to-be-determined object with a thickness of 1.5 mm. The flowchart showing operation | movement of the recycled resin determination apparatus which concerns on Embodiment 1. Schematic diagram illustrating a first modification of the reference unit according to the first embodiment. FIG. 6 is a schematic diagram illustrating a second modification of the reference unit according to Embodiment 1, wherein (a) a schematic diagram of the entire reference unit, and (b) a schematic diagram of a rotating body provided in the reference unit. Block diagram showing an apparatus for manufacturing a recycled resin material according to Embodiment 2 Schematic diagram of a recycled resin determination device according to the prior art

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals and description thereof is omitted.

(Embodiment 1)
FIG. 1 is a schematic diagram of a recycled resin determination device 100 according to the first embodiment.

  The hopper 102 disposed at the start end of the conveyance path by the conveyor belt 101 vibrates and swings. As a result, the plurality of determination objects 103 loaded on the hopper 102 are sequentially put on the conveyor belt 101 with a certain interval.

  The conveyance speed of the object 103 to be determined by the conveyor belt 101 is 3 m / s, and the conveyance direction is the direction of arrow A shown in FIG.

  The determination target object 103 is a mixed plastic made of a plurality of types of transparent resins, and includes a transparent recycled resin. The to-be-determined object 103 is composed of small pieces each having a side of about 5 mm to several tens of millimeters.

  The object 103 to be judged reflects infrared light (infrared reflected light) 105 that is a characteristic amount of each resin material by being irradiated with infrared light by the infrared light source 104.

For the infrared light source 104, 1350 to 2500 nm (1350 nm to 2500 nm)
A halogen lamp that irradiates infrared light (near infrared light) in a broad wavelength band. Here, since the wavelength at which the light absorption phenomenon as the characteristic amount occurs varies depending on the type of the resin, it is determined based on the wavelength at which the light absorption phenomenon has occurred whether or not the determination target object 103 is a recycled resin. The wavelength at which the light absorption phenomenon occurs can be obtained from the absorption spectrum of the reflected infrared light 105. The infrared light source 104 may be a laser light source that emits light having a wavelength band of 1350 to 2500 nm.

  The infrared light 105 reflected by the determination object 103 is detected by the detection unit 106, and the detection result is converted into digital data and then transferred to the arithmetic processing unit 107.

  The arithmetic processing unit 107 determines whether or not the determination target object 103 is a recycled resin.

  Detailed descriptions of the detection unit 106 and the arithmetic processing unit 107 will be described later.

  A determination target 103 (hereinafter referred to as recycled resin 103a) determined to be recycled resin is stored in a recycling box 109 by being blown off by air from a pulsed air nozzle 108 installed above the terminal end of the conveyor belt 101. The On the other hand, the determination object 103 determined not to be recycled resin (hereinafter referred to as non-recycled resin 103b) is stored in the non-recycle box 110 without being blown off by the pulse air nozzle 108. In this case, the non-recycle box 110 is disposed below the end portion of the conveyor belt 101 and at a position where the determination target object 103 freely falls. Thus, only the recycled resin 103a can be selected from the plurality of determination objects 103.

  Next, the detection unit 106 will be described with reference to FIG. FIG. 2 shows the detection unit 106 from the X-axis direction of FIG. The detection unit 106 functions as a thickness measurement unit that measures the thickness of the determination target 103 and an absorption spectrum calculation unit that calculates an absorption spectrum as a feature amount of the infrared light 105 reflected by the determination target 103. It is to be prepared.

  First, the function of the detection unit 106 as a thickness measuring unit will be described.

  The thickness measuring unit is an optical interferometer that measures the thickness of the determination target object 103 by irradiating the reference unit 112 and the determination target object 103 with measurement light from the light source 111 and causing the reflected light to interfere with each other. It has the function of. A Michelson interferometer configuration was used as the optical interferometer.

  The light source 111 for thickness measurement is a wavelength scanning optical coherence tomography apparatus (hereinafter referred to as SS-OCT). Here, since a silicon avalanche photodiode is used as the light receiving element 113 that receives light, light having a wavelength of 780 to 860 nm, which is sensitive to the light receiving element 113, is used as measurement light. In addition, the wavelength of measurement light should just be other than the wavelength 1350-2500 nm irradiated with the infrared light source 104 shown in FIG. In addition, with visible light, the thickness may not be accurately measured. For these reasons, it is preferable to use light having a wavelength of 780 to 1350 nm as measurement light from the light source 111.

  The measurement light emitted from the light source 111 passes through a narrow band filter 114 that transmits light having a wavelength of 780 to 860 nm, and is divided into two by the beam splitter 115.

  Of the light divided by the beam splitter 115, the light irradiated to the object 103 or the conveyor belt 101 (hereinafter referred to as object light) is reflected by the polygon mirror 116 and passes through the telecentric fθ lens 117. Is irradiated. The polygon mirror 116 is capable of scanning in the width direction (Y-axis direction) of the conveyor belt 101 by rotating itself, and the object reflected from each scan point (position where the object light is irradiated) on the conveyor belt 101. Allows detection of light.

  The telecentric fθ lens 117 has an fθ function that equalizes the difference in scanning speed between the center and the periphery of the polygon mirror 116. In this case, the telecentric fθ lens 117 is formed of a conveyor belt 101 and a telecentric optical system.

  In order to correct the difference in the optical path length of the object light depending on the angle incident on the telecentric fθ lens 117 by the rotation of the polygon mirror 116, the telecentric fθ lens 117 is thinned from the center to both ends on the conveyor belt 101 side. A glass body (not shown) is installed. The glass body is shaped based on the refractive index of the glass body so that the object light reflected by the polygon mirror 116 is irradiated onto the conveyor belt 101 with the same optical path length no matter what angle the light enters the telecentric fθ lens. Is designed.

  The object light irradiated to the determination target object 103 via the telecentric fθ lens 117 is reflected by the surface of the determination target object 103, travels backward in the same path, and enters the beam splitter 115 again.

  Of the light divided by the beam splitter 115, light different from the measurement light (hereinafter referred to as reference light) passes through a narrowband filter 118 and a condensing lens 119 that transmit light having a wavelength of 780 to 860 nm. 112 is incident.

  The reference unit 112 includes a fiber-type optical demultiplexer 120 that demultiplexes incident reference light for each wavelength, and a reflection mirror group 121 that reflects the demultiplexed reference light at different positions for each wavelength. is there. The reference light reflected by the reflection mirror group 121 travels backward in its optical path, and is combined with one light beam again by the fiber type optical demultiplexer 120 and then emitted from the reference unit 112. The reference light emitted from the reference unit 112 enters the beam splitter 115 again via the condenser lens 119 and the narrow band filter 118. Since the reflection mirror group 121 reflects the light at different positions for each wavelength, the reference light emitted from the reference unit 112 is given a different optical path length for each wavelength.

  The object light reflected by the surface of the determination target object 103 and the reference light emitted from the reference unit 112 are incident on the beam splitter 115 again, and are combined into one light beam (becomes interference light).

  The interference light is reflected and diffracted by the diffraction grating 122 and dispersed at different angles for each wavelength.

  The separated interference light is incident on the light receiving surface of the light receiving element 113 through the condenser lens 123 and the narrow band filter 124 that transmits light having a wavelength of 780 to 860 nm.

  The light receiving element 113 has a plurality of light receiving surfaces, and the interference light separated by the diffraction grating 122 for each wavelength is incident on each light receiving surface. The light receiving element 113 photoelectrically converts the interference light incident on each light receiving surface into a current. The analog data converted into current is converted into digital data by the optical gain current / voltage conversion amplifier 125 and the high-speed AD conversion circuit 126. The converted digital data is sent to the arithmetic processing unit 107. At this time, the thickness of the determination target object 103 is calculated by the arithmetic processing unit 107 based on the wavelength of the light whose intensity is increased by the interference. In the following description, the measured thickness of the determination target object 103 is referred to as a measured thickness.

  The narrow-band filters 114, 118, and 124 are installed in order to prevent light of 1350 to 2500 nm used for calculating an absorption spectrum from being incident as noise on light of 780 to 860 nm used for thickness measurement.

  Next, a function as an absorption spectrum calculation unit provided in the detection unit 106 will be described.

  When measuring the thickness of the determination target 103, the object light reflected by the determination target 103 enters the beam splitter 115 via the telecentric fθ lens 117 and the polygon mirror 116. At this time, the infrared light 105 reflected by the determination target object 103 also enters the beam splitter 115 through the same path as the object light.

  The infrared light 105 incident on the beam splitter 115 enters the diffraction grating 122 through the same path as the interference light. The diffraction grating 122 reflects and diffracts incident interference light and infrared light 105 at different angles for each wavelength. At this time, light having a wavelength of 780 to 860 nm as interference light is incident on the condensing lens 123, and light having a wavelength of 1350 to 2500 nm as infrared light 105 is incident on the condensing lens 127. , Condenser lenses 123 and 127 are arranged.

  The infrared light 105 incident on the condenser lens 127 is transmitted through the narrowband filter 128 that transmits light having a wavelength of 1350 to 2500 nm and is incident on the light receiving surface of the infrared light receiving unit 129.

  The infrared light receiving unit 129 has a plurality of light receiving surfaces, and the infrared light 105 dispersed by the diffraction grating 122 for each wavelength is incident on each light receiving surface. The infrared light receiving unit 129 photoelectrically converts the received infrared light 105 into a current. The converted current is sent to the arithmetic processing unit 107 via the optical gain current-voltage conversion amplifier 130 and the high-speed AD conversion circuit 131. At this time, the light intensity varies depending on the wavelength due to the light absorption phenomenon of the determination target object 103. Therefore, the arithmetic processing unit 107 obtains the intensity distribution of the infrared light 105 for each wavelength of the determination target object 103, and calculates an absorption spectrum.

  A wavelength filter 132 that blocks light having a wavelength of 780 nm or less is disposed between the conveyor belt 101 and the telecentric fθ lens 117. This is because light having a wavelength other than 780 to 2500 nm used for thickness measurement or absorption spectrum calculation enters a noise factor. However, since light having a wavelength of 2500 nm or longer has a large transmission loss in a general optical system made of resin or glass and is naturally filtered, it is sufficient to cut light having a wavelength of 780 nm or shorter.

  Next, a specific method for determining whether the determination target object 103 is a recycled resin will be described.

  FIG. 3 shows the absorption spectrum of transparent PS having a thickness of 1 mm, 2 mm, and 3 mm. In FIG. 3, the vertical axis represents absorbance and the horizontal axis represents wavelength (μm). These absorption spectra are calculated by an absorption spectrum calculator provided in the detection unit 106 shown in FIG. Further, an absorption spectrum of PS that is not transparent is shown as a reference absorption spectrum (referred to as reference in FIG. 3). From this, it can be seen that transparent PS and non-transparent PS show different absorption spectra. Moreover, it turns out that transparent PS changes an absorption spectrum with thickness. The reference absorption spectrum is constant regardless of the resin thickness.

  When infrared light is irradiated to the determination target 103 shown in FIG. 1, the infrared light 105 reflected by the determination target 103 is transmitted from a conveyance path (conveyor belt 101) located below the determination target 103. Of infrared light will overlap. Therefore, when the infrared light 105 reflected by the determination target 103 is received, the infrared light 105 from the conveyance path is also received.

  Further, the influence of the infrared light 105 from the conveyor belt 101 changes depending on the thickness of the determination target object 103. This can be understood from the results of FIG. That is, as a result of experiments by the inventors, it has become clear that the absorption spectrum of a transparent recycled resin changes depending on the thickness.

  Therefore, for a plurality of transparent recycled resins that differ only in thickness conditions, an absorption spectrum corresponding to each thickness is prepared in advance as reference data. Among the prepared reference data, the reference data for the recycled resin having a thickness corresponding to the measured thickness of the determination target object 103 is selected (hereinafter referred to as selection reference data), and the selection reference data and the absorption spectrum of the determination target object 103 are It is possible to determine whether the determination target object 103 is a recycled resin.

  A determination processing method performed by the arithmetic processing unit 107 will be described. FIG. 4 shows a block diagram of the arithmetic processing unit 107.

  The arithmetic processing unit 107 stores, as reference data, a plurality of types of absorption spectra for each thickness of the transparent recycled resin, a storage unit 107a stored in advance, a measured thickness and an absorption spectrum of the determination target 103, and a storage unit 107a. And a determination unit 107b that performs a determination process as to whether or not the determination target object 103 is a recycled resin based on a plurality of stored reference data. The measured thickness and absorption spectrum of the determination object 103 are input to the determination unit 107b in FIG. 4 by the thickness measurement unit and the absorption spectrum calculation unit provided in the detection unit 106 illustrated in FIG.

  A determination processing method performed by the determination unit 107b will be described with reference to the flowcharts illustrated in FIGS.

  First, reference data (selection reference data) for a recycled resin having a thickness equal to the measured thickness of the determination target object 103 input from the detection unit 106 is selected from a plurality of reference data stored in the storage unit 107a. (S1).

  Next, the absorption spectrum of the determination object 103 is compared with the absorption spectrum of the determination object 103 input from the detection unit 106 and the selection reference data (S2). At this time, the input absorption spectrum is subjected to spectrum leveling after the gain is adjusted.

  Finally, based on the comparison in step S2, it is determined whether the determination target object 103 is a recycled resin (S3). As a determination method in step S <b> 3, a chemometric method for extracting necessary information from multivariate feature amounts of the absorption spectrum is used. The chemometrics method is to estimate an effective result by an optimum processing method using a mathematical method or a statistical method from the calculated multivariate data. As other methods, a linear multiple regression analysis method, a principal component analysis method, or a PLS (Partial Least Squires) regression analysis method may be used. Further, cluster analysis may be used, and among them, Mahalanobis distance or asymmetric Mahalanobis distance may be used.

  As described above, the determination unit 107b determines whether or not the determination target object 103 is a recycled resin.

  By the way, in step S1, the determination unit 107b selects the reference data for the recycled resin having a thickness equal to the measured thickness as the selection reference data from the plurality of reference data stored in the storage unit 107a. The to-be-determined object 103 constituting the mixed plastic includes various thicknesses. That is, in order to select reference data having a thickness equal to the measured thickness, an enormous amount of reference data must be stored in the storage unit 107a in advance. If the amount of reference data to be handled becomes enormous, a burden is imposed on the determination unit 107b that selects specific reference data from among them. For this reason, the processing speed of the determination unit 107b may be reduced.

  Therefore, the inventors select the selection criterion data so that the difference between the thickness corresponding to the selection criterion data and the measured thickness of the determination target object 103 is 0.5 mm or less, which matches the measured thickness. As a result of experiments, it has been found that determination of recycled resin is possible without causing a decrease in determination accuracy without using reference data for thickness recycled resin. This will be described based on the experimental data shown below.

  From FIG. 3, it can be said that the noise corresponding to each thickness is on the reference absorption spectrum in the transparent PS absorption spectrum. That is, it can be said that the reference data includes a reference absorption spectrum and noise corresponding to the thickness. The noise here refers to an absorption spectrum caused by reflected light (infrared light 105) from the conveyance path (conveyor belt 101).

  Since the reference absorption spectrum is constant regardless of the thickness of the resin, the noise changes due to the thickness. That is, if noise corresponding to the thickness of the resin is subtracted from the calculated absorption spectrum of the resin, determination based only on the reference absorption spectrum independent of the thickness can be performed.

  Accordingly, FIG. 6 shows a result obtained by subtracting noise corresponding to 2 mm and 3 mm PS from the absorption spectrum calculated for PS having a thickness of 1 mm, and a reference absorption spectrum of PS. In FIG. 6, the vertical axis represents absorbance and the horizontal axis represents wavelength (μm). As a feature quantity of an absorption spectrum of PS, it is known that a peak is shown in a wavelength band of 1.763 μm. The P1 region in FIG. 6 is where the peak of the PS absorption spectrum appears. In the P1 area, noise obtained by subtracting noise corresponding to 2 mm and 3 mm has a variation from the reference absorption spectrum, and thus cannot be determined with high accuracy. From this, it can be understood that when there is a difference of 1 mm or more between the measured thickness of the determination target object 103 and the thickness corresponding to the selection reference data, the determination cannot be performed with high accuracy.

  Next, FIG. 7 shows a result obtained by subtracting noise corresponding to 1 mm PS from the absorption spectrum calculated for PS having a thickness of 1.5 mm. In FIG. 7, the vertical axis represents absorbance and the horizontal axis represents wavelength (μm). The P2 region in FIG. 7 is where the peak of the PS absorption spectrum appears. As described above, when correction is performed using noise having a difference of 0.5 mm with respect to the measured thickness of the determination target object 103, a peak indicating a feature amount can be confirmed, and determination can be performed with high accuracy. It is.

  As a result of conducting an experiment as shown in the example above, the inventors used the reference data in the recycled resin having a thickness within 0.5 mm as a difference from the measured thickness of the determination target object 103 as the selection reference data. It has been found that it is possible to determine whether the determination object 103 is a recycled resin.

  That is, it can be understood that the storage unit 107a in FIG. 4 may store reference data for recycled resin having a thickness of 1 mm. This is because the maximum difference between the thickness of the selection reference data and the measured thickness is 0.5 mm. Thereby, it is possible to reduce the amount of reference data to be stored in the storage unit 107a in advance. In addition, the determination unit 107b can perform processing at high speed because the amount of reference data to be selected is reduced.

  Further, the inventors have found that the order of measuring the thickness of the determination target object 103 may be 1 mm. This is because if the thickness (measurement thickness) of the object to be determined 103 is measured at intervals of 1 mm, the difference between the measured thickness and the actual thickness of the object to be determined 103 is 0.5 mm or less. In this case, the reference data for the recycled resin having a thickness corresponding to the measurement interval may be stored in the storage unit 107a.

  The reference unit 112 shown in FIG. 2 will be described as means for measuring the measured thickness of the determination target object 103 at intervals of 1 mm.

  The reference unit 112 includes a fiber-type optical demultiplexer 120 that demultiplexes incident reference light for each wavelength, and a reflection mirror group that includes a plurality of mirrors that reflect the demultiplexed reference light so as to have different optical path lengths. 121. Since the wavelength included in the reference light is set to 780 to 860 nm, here, the fiber-type optical demultiplexer 120 divides the light into wavelengths of 780 nm, 800 nm, 820 nm, 840 nm, and 860 nm. In this case, each mirror constituting the reflection mirror group 121 is arranged so as to give different optical path length differences for each wavelength at intervals of 1 mm. Specifically, the mirror 121a that reflects the reference light of 780 nm is arranged so that the optical path length of the light of 780 nm included in the reference light is 1 mm shorter than the optical path length of the object light reflected by the conveyor belt 101. Yes. A mirror 121b that reflects the 800 nm reference light is arranged so that the optical path length of the 800 nm light included in the reference light is 2 mm shorter than the optical path length of the object light reflected from the conveyor belt 101. Similarly, the mirror 121c that reflects the reference light having a wavelength of 820 nm, the mirror 121d that reflects the reference light having a wavelength of 840 nm, and the mirror 121e that reflects the reference light having a wavelength of 860 nm are different in optical path length between the object light and the reference light. Are arranged so as to be 3 mm, 4 mm, and 5 mm. Thereby, when the reference light and the object light are caused to interfere with each other, it is possible to measure the optical path length of the object light by detecting the strengthened wavelength.

  Since the object light is reflected by the surface of the determination object 103, for example, when light having a wavelength of 780 nm is strengthened by interference, the surface of the determination object 103 is at a position (height) of 1 mm from the conveyor belt 101. I understand that there is. Since the determination object 103 is crushed into small pieces as a mixed plastic, the position (height) of the surface of the determination object 103 from the conveyor belt 101 can be regarded as the thickness of the determination object 103. Therefore, the thickness of the determination target object 103 can be measured by measuring the optical path length of the object light.

  Still another specific example will be described. When the thickness of the object to be determined 103 is 1.2 mm, reference light having a wavelength corresponding to a thickness of 1 mm (780 nm) and a wavelength corresponding to 2 mm (800 nm) causes interference with object light. In this case, since interference with reference light having a wavelength (780 nm) corresponding to a thickness of 1 mm occurs more strongly, the thickness (measurement thickness) of the determination target object 103 is measured as 1 mm. Further, when the thickness of the object to be determined 103 is 1.7 mm, interference due to reference light having a wavelength (800 nm) corresponding to 2 mm occurs more strongly, so the thickness (measurement thickness) of the object to be determined 103 is measured as 2 mm. . At this time, determination is performed using the reference data (selection reference data) for the recycled resin having a thickness of 1 mm, with respect to the determination target object 103 having a measured thickness of 1.0 mm and a thickness of 1.2 mm. Further, the determination object 103 having an actual thickness of 1.7 mm with a measured thickness of 2 mm is determined by using the reference data (selection reference data) for the recycled resin having a thickness of 2 mm.

  Thus, if the measured thickness is measured at intervals of 1 mm, the difference from the actual thickness is 0.5 mm or less, so it is possible to use reference data prepared at intervals of 1 mm. Thereby, the number of reference data to be prepared in advance can be reduced. Furthermore, since the thickness is measured at intervals of 1 mm, the load on the arithmetic processing unit 107 can be reduced. In this case, it is necessary to prepare reference data in which the thickness interval to be measured is matched with the corresponding thickness.

  In the first embodiment, since the determination target 103 having a thickness of about 0.3 to 5.5 mm is assumed, the number of mirrors of the reflection mirror group 121 in the reference unit 112 is five, and the reference data to be prepared Also, 5 types corresponding to thicknesses of 1 mm to 1 mm are provided at intervals of 1 mm. If the thickness variation of the determination target 103 changes, the number of mirrors may be set to 6 or more and 4 or less, and the type of reference data may be changed. Furthermore, the wavelength of the measurement light emitted from the light source 111 may be changed in the range of 780 to 1350 nm.

  In addition, the coherence distance of the light source 111 is set to 1 mm or more in order to cause interference with reference light having optical path lengths of 1 mm intervals. Furthermore, it is desirable that the coherence distance is less than 2 mm so that the reference lights having three or more types of wavelengths do not interfere simultaneously.

  Note that the thickness of the determination target object 103 can be measured with an accuracy of 0.1 mm or less from the ratio of the intensity of the interference light of each wavelength. For example, in the object 103 having a thickness of 1.2 mm and the object 103 having a thickness of 1.3 mm, the interference intensity of the reference light having a wavelength corresponding to 1 mm (780 nm) and the wavelength corresponding to 2 mm (800 nm) The difference from the interference intensity of the reference light is different. Therefore, by measuring the difference in interference intensity in advance, the measurement thickness can be measured with an accuracy of 0.1 mm or less.

  Although the case where the object to be determined 103 is PS has been described here, the same result can be obtained even if the object to be determined 103 is other resin such as PP or ABS. At this time, regardless of the type of resin, the determination object 103 can be determined with high accuracy by subtracting the correction data corresponding to the thickness from the calculated absorption spectrum. However, if correction data corresponding to each type of resin is used, it is possible to determine the resin with higher accuracy. This is because if the thickness of the resin is increased, the resin is affected by absorption by the resin itself, and the correction data corresponding to the thickness may be different for each type of resin due to this. When the thickness is smaller than 0.5 mm, the absorption spectrum (conveyance path absorption spectrum) of the conveyance path (conveyor belt 101) may be used as the correction data.

  The determination object 103 may be determined based on the absorption spectrum of the determination target object 103 obtained by subtracting noise and the reference absorption spectrum. The reference absorption spectrum obtained by adding the noise and the absorption spectrum of the determination target object 103 may be determined. Based on the above, the determination object 103 may be determined. Further, a reference absorption spectrum to which noise is added may be prepared in advance as a reference spectrum, and the determination target 103 may be determined based on the reference spectrum and the absorption spectrum of the determination target 103.

  Next, the flow of the resin discrimination method by the recycled resin determination apparatus 100 shown in FIG. 1 will be described with reference to FIG.

  First, by the operation of the hopper 102, the determination target object 103 disposed on the upper part is dropped onto an arbitrary place on the conveyor belt 101 (S21).

  Next, since the conveyor belt 101 is always in operation, the conveyor belt 101 is carried downward by the flow of the detection unit 106, and the detection unit 106 measures the measured thickness of the object 103 and calculates the absorption spectrum. (S22).

  Based on the measured thickness of the object to be determined 103 and the absorption spectrum, it is determined whether or not the object to be determined 103 is a recycled resin. The determination means is as shown in the flow of FIG. 5 (S23).

  The to-be-determined object 103 (recycled resin 103a) determined to be recycled resin is blown off by the pulse air nozzle 108 and stored in the recycle box 109 (S24).

  The to-be-determined object 103 (non-recycled resin 103b) determined not to be recycled resin is not blown out by the pulse air nozzle 108 and is stored in the non-recycled box 110 by free fall (S25).

  As described above, it is possible to determine the recycled resin 103a from the objects to be determined 103 and select only the determined recycled resin 103a.

  If a plurality of lines of pulse air nozzles 108 as a sorting mechanism are arranged and a recycle box 109 corresponding to each is prepared, sorting such as PP and PS can be performed.

  Further, in order to select the determination target 103 with high accuracy, the position of the determination target 103 needs to be determined with high accuracy. The recycled resin determination device 100 reads the value from the encoder detector of the conveyor belt 101 controlled by a control mechanism (not shown) and the scan position of the detection unit 106 to thereby read the determination object 103 on the conveyor belt 101. The position can be specified.

  Note that the thickness measurement unit and the absorption spectrum calculation unit provided in the detection unit 106 are synchronized by the external clock, but basically the measurement thickness data and the absorption spectrum data are calculated at the same measurement point at the same time. It will be.

  A metal sensor may be installed above the conveyor belt 101. When it is determined by the metal sensor that metal exists around the object 103, the object 103 is stored in the non-recycle box 110 regardless of whether or not it is recycled resin. This is for preventing metal from being mixed into the recycle box 109 together with the recycle resin 103a.

  Further, a high speed line CCD camera may be installed above the conveyor belt 101. If it is determined by the high-speed line CCD camera that there is a black foreign object that does not reflect infrared light, the determination object 103 located around the foreign object is transferred to the non-recycle box 110 regardless of whether it is recycled resin or not. And store. This is to prevent black foreign matters that cannot be confirmed by the detection unit 106 from entering the recycle box 109.

  Here, a resin having a total light transmittance of 70% or more has been described as a transparent resin.

<Modification 1>
FIG. 9 shows a reference unit 133 that is a modification of the reference unit 112 of the first embodiment.

  In the reference unit 112 shown in FIG. 2, the size of the fiber type optical demultiplexer 120 is a problem, and it is difficult to reduce the size. Therefore, the reference unit 133 is reduced in size by using a diffraction grating 134 instead of the fiber type optical demultiplexer 120.

  The reference light incident on the reference unit 133 is split into wavelengths of 780 nm, 800 nm, 820 nm, 840 nm, and 860 nm by the diffraction grating 134 and reflected by the reflection mirror group 136 through the condenser lens group 135. The reference light reflected by the reflection mirror group 136 is emitted from the reference unit 133 so as to travel backward in its optical path. In this case, the diffraction grating 134, the condensing lens group 135, and the reflecting mirror group 136 are arranged so that different optical path lengths are given to the reference light of each wavelength at intervals of 1 mm.

  Thereby, the same effect as that of the reference unit 112 can be achieved while downsizing the apparatus.

<Modification 2>
FIG. 10A shows a reference unit 137 that is another modification of the reference unit 112 of the first embodiment.

  In the reference unit 112 shown in FIG. 2, the size of the fiber type optical demultiplexer 120 becomes a problem, and in the reference unit 133, it is not easy to position the diffraction grating 134, the condenser lens group 135, and the reflection mirror group 136. It becomes a problem. In view of this, the reference unit 137 uses a rotating body 138 and a reflection mirror 139 instead of these to reduce the size of the apparatus and simplify the positioning.

  The reference light incident on the reference unit 137 is reflected by the reflecting mirror 139 via the rotating body 138. The reference light reflected by the reflection mirror 139 is emitted from the reference unit 137 so as to travel backward in the optical path.

  FIG. 10B illustrates the rotating body 138 illustrated in FIG. 10A from the direction in which the reference light is incident.

  The rotator 138 includes a plurality of narrow band filters 140a to 140e having different wavelengths to be transmitted. The narrow band filters 140a to 140e have different thicknesses. As a result, the optical distance to the reflection mirror 139 changes according to the wavelength. In the second modification, the narrowband filter 140a transmits the reference light of 780 nm, 140b of 800 nm, 140c of 820 nm, 140d of 840 nm, and 140e of 860 nm. Further, the thickness of each filter was changed at a pitch of 0.33 mm. This is because light passes through each filter twice, and the refractive index of the filter itself is about 1.5. Thereby, the measured thickness of the determination target object 103 can be acquired at intervals of 1 mm.

  Thus, the same effects as those of the reference units 112 and 133 can be achieved while the apparatus is downsized and positioning is simplified.

  In the second modification, it is necessary to rotate the rotating body 138 at a speed five times the rotational speed of the polygon mirror 116. This is because the measurement thickness is measured at all wavelengths.

(Embodiment 2)
A recycled resin material manufacturing apparatus 141 according to Embodiment 2 will be described with reference to FIG. The recycled resin material manufacturing apparatus 141 includes the recycled resin determination apparatus 100 according to the first embodiment and the recycled resin molding apparatus 142. As the recycled resin molding device 142, one described in Japanese Patent Laid-Open No. 2001-205632 can be used.

  The recycled resin material manufacturing apparatus 141 according to the second embodiment can mold the resin material using the determination target object 103 (recycled resin 103a) determined to be recycled resin. For this reason, it is possible to save resources.

  According to the present invention, it is possible to determine a desired recycled resin from a crushed mixed plastic for recycling from a waste home appliance or the like.

DESCRIPTION OF SYMBOLS 100 Recycled resin determination apparatus 101 Conveyor belt 103 To-be-determined object 104 Infrared light source 106 Detection unit 107 Arithmetic processing part 107a Memory | storage part 107b Judgment part 129 Infrared light-receiving part 111 Light source 141 Recycled resin material manufacturing apparatus 142 Recycled resin molding apparatus

Claims (5)

A transport path for transporting an object to be determined, which is a transparent resin;
An infrared light source for irradiating the determination object with infrared light;
An infrared light receiving unit that receives infrared reflected light from the object to be judged irradiated with the infrared light; and
An absorption spectrum calculation unit for calculating an absorption spectrum of the determination object from the infrared reflected light;
A measurement unit for measuring a measurement thickness which is the thickness of the object to be determined;
A storage unit in which a plurality of types of recycled resin reference data is stored in advance for each thickness of the recycled resin,
Reference data for the recycled resin having a thickness corresponding to the measured thickness among the reference data is selected as selection reference data, and whether the determination target is the recycled resin based on the selection reference data and the absorption spectrum. A recycled resin determination device comprising: a determination unit that determines   The determination unit selects, as selection reference data, reference data for the recycled resin having a thickness that makes a difference from the measured thickness of 0.5 mm or less among the plurality of types of reference data stored, and the selection reference data and the selection data 2. The recycled resin determination apparatus according to claim 1, wherein it is determined whether or not the object to be determined is the recycled resin based on an absorption spectrum.   The recycled resin determination device according to claim 1, wherein the measurement unit measures the measurement thickness by an optical interferometer that uses measurement light having a wavelength different from that of the infrared light. The infrared light source irradiates infrared light having a wavelength of 1350 to 2500 nm,
The recycled resin determination apparatus according to claim 3, wherein the optical interferometer uses measurement light having a wavelength of 780 to 1350 nm.   The manufacturing apparatus of the recycled resin material which shape | molds the to-be-determined object determined with the said recycled resin by the recycled resin determination apparatus of any one of Claims 1-4, and manufactures a recycled resin material.

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