Paper type discriminating apparatus, paper type discriminating method, and recording medium

Abstract

This invention provides a reliable paper type identification device, a paper type identification method, and a recording medium for identifying recycled paper. The paper type identification device (2) comprises: a first light source unit that illuminates the paper with light having a first wavelength and light having a second wavelength; a detection unit that detects the light from the paper and acquires a detection value based on the light; and a control unit that uses the detection value to derive a determination result of the paper type. The first light source unit and the detection unit are located on the same side relative to the paper. The detection value includes: a first detection value based on the light from the paper when the paper is illuminated with light having the first wavelength; and a second detection value based on the light from the paper when the paper is illuminated with light having the second wavelength. The control unit identifies a first type of recycled paper using a first processing step with the first detection value, and identifies a second type of recycled paper different from the first type using a second processing step with the second detection value.

Description

Technical Field

[0001] This invention relates to a paper type identification device, a paper type identification method, and a recording medium. Background Technology

[0002] The fixing conditions of an image forming apparatus vary depending on the type of paper, thus requiring settings corresponding to that paper type. Previously, users input the paper type into the control panel, but in recent years, paper type detection devices have been developed that automatically detect the paper type using a sensor and change the settings accordingly. These automatic paper type detection devices determine the paper type based on the light emitted from the paper when it is illuminated.

[0003] Japanese Patent Application Publication No. 2020-64003 discloses a method for identifying recycled paper based on the amount of reflected light when the paper is irradiated with light of a certain wavelength.

[0004] Japanese Patent Application Publication No. 2005-335869 discloses a method for accurately identifying the type of the first medium when the paper type is determined by irradiating the laminated thin media (paper) with light.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-64003

[0006] Patent Document 2: Japanese Patent Application Publication No. 2005-335869

[0007] The method disclosed in Japanese Patent Application Publication No. 2020-64003 utilizes the property that recycled paper reflects less light than other types of paper. The reason recycled paper reflects less light is that the waste paper pulp contained in it absorbs the emitted light. However, even with the method disclosed in Japanese Patent Application Publication No. 2020-64003, it is sometimes impossible to identify a portion of recycled paper as recycled paper. Summary of the Invention

[0008] One of the objectives of this invention is to provide a technology that can reliably identify recycled paper.

[0009] A paper type identification apparatus according to a certain aspect of the present invention includes: a first light source unit that illuminates light having a first wavelength and light having a second wavelength toward the paper; a detection unit that detects the light from the paper and acquires a detection value based on the light; and a control unit that uses the detection value to derive a determination result of the paper type. The first light source unit and the detection unit are located on the same side relative to the paper. The detection value includes: a first detection value based on the light from the paper when the paper is illuminated with light having the first wavelength; and a second detection value based on the light from the paper when the paper is illuminated with light having the second wavelength. The control unit identifies a first type of recycled paper by using a first processing of the first detection value, and identifies a second type of recycled paper different from the first type of recycled paper by using a second processing of the second detection value.

[0010] Preferably, the light with the second wavelength is ultraviolet light. The second type of recycled paper contains more phosphors compared to the first type of recycled paper. The second process includes using a second detection value to distinguish between the coated paper and the second type of recycled paper.

[0011] Preferably, the first light source unit also illuminates the paper with light having a third wavelength. The detection value also includes a third detection value based on the light from the paper when the paper is illuminated with light having a third wavelength. The second processing includes: calculating reflectance based on the second detection value; calculating reflectance based on the third detection value; and determining the coated paper and the second type of recycled paper based on the ratio of the reflectance calculated based on the second detection value to the reflectance calculated based on the third detection value. Preferably, the light having the third wavelength is infrared light.

[0012] Preferably, the light with the second wavelength is ultraviolet light. The second type of recycled paper contains more phosphors compared to the first type of recycled paper. The second process includes using a second detection value and a first detection value to distinguish between the coated paper and the second type of recycled paper.

[0013] Preferably, the first light source unit also illuminates the paper with light having a third wavelength. The detection value also includes a third detection value based on the light from the paper when the paper is illuminated with light having a third wavelength. The second process includes: calculating reflectance based on the first detection value; calculating reflectance based on the second detection value; calculating reflectance based on the third detection value; and distinguishing between coated paper and a second type of recycled paper based on the ratio of the reflectance calculated based on the first detection value to the reflectance calculated based on the third detection value, and the ratio of the reflectance calculated based on the second detection value to the reflectance calculated based on the third detection value. Preferably, the light having a third wavelength is infrared light.

[0014] Preferably, the peak wavelength of the light having the first wavelength is 390 nm or more and less than 550 nm. The first type of recycled paper contains fewer phosphors compared to the second type of recycled paper. The first process includes using a first detection value to identify the first type of recycled paper.

[0015] Preferably, the first light source unit also illuminates the paper with light having a third wavelength. The detection value also includes a third detection value based on the light from the paper when the paper is illuminated with light having a third wavelength. The first process includes: calculating reflectance based on the first detection value; calculating reflectance based on the third detection value; and identifying a first type of recycled paper based on the ratio of the reflectance calculated based on the first detection value to the reflectance calculated based on the third detection value. Preferably, the light having the third wavelength is infrared light.

[0016] Preferably, the peak wavelength of the light having the first wavelength is 390 nm or more and less than 440 nm, and the peak wavelength of the light having the second wavelength is 340 nm or more and less than 390 nm.

[0017] Preferably, the paper type identification device further includes a second light source unit, which is located on the side opposite to the side where the detection unit is disposed, relative to the paper. The second light source unit also illuminates the paper with light having a fourth wavelength and light having a fifth wavelength. The detection values ​​also include: a fourth detection value based on the light from the paper when the paper is illuminated with light having the fourth wavelength; and a fifth detection value based on the light from the paper when the paper is illuminated with light having the fifth wavelength. The control unit further identifies ordinary paper by using a third processing of the fourth and fifth detection values.

[0018] Preferably, the light with the fourth wavelength is infrared light, and the light with the fifth wavelength is blue light.

[0019] Another aspect of the paper type identification method of the present invention includes: irradiating the paper with light having a first wavelength and light having a second wavelength; detecting the light from the paper and obtaining a detection value based on the light; and using the detection value to derive a paper type identification result. The position where the light having the first wavelength is generated, the position where the light having the second wavelength is generated, and the detection position of the light from the paper are located on the same side relative to the paper. The detection value includes: a first detection value based on the light from the paper when the paper is irradiated with light having the first wavelength; and a second detection value based on the light from the paper when the paper is irradiated with light having the second wavelength. The derived paper type identification result includes: identifying a first type of recycled paper using a first process with the first detection value; and identifying a second type of recycled paper different from the first type of recycled paper using a second process with the second detection value.

[0020] In other embodiments of the present invention, a computer-readable recording medium stores a paper type identification program that causes a computer to execute the paper type identification method described above.

[0021] According to the present invention, recycled paper can be reliably identified. Attached Figure Description

[0022] Figure 1 This is a diagram showing the schematic structure of the image forming apparatus according to Embodiment 1.

[0023] Figure 2 This is a diagram showing the hardware structure of the image forming apparatus 1.

[0024] Figure 3 This is a diagram showing an example of the structure of the inspection section 20.

[0025] Figure 4 This is a diagram illustrating the light detected by the light-receiving element 220 when light is irradiated from the first light source unit 21X through the inspection unit 20 at a timing.

[0026] Figure 5 This is a diagram illustrating the light detected by the light-receiving element 220 when the paper M is not illuminated by light from the first light source unit 21X at the timing of the inspection section 20.

[0027] Figure 6 This is a diagram illustrating the light detected by the light-receiving element 220 when light is irradiated from the second light source unit 21Y through the inspection unit 20 at a timing.

[0028] Figure 7 This is a diagram illustrating the light detected by the light-receiving element 220 when the paper M is not illuminated by light from the second light source unit 21Y at the timing of the inspection section 20.

[0029] Figure 8 This is a flowchart illustrating the sequence of paper type identification processing in Implementation Method 1.

[0030] Figure 9 This is a diagram used to illustrate the first process of Implementation Method 1.

[0031] Figure 10 This is a diagram used to illustrate the second process of Implementation Method 1.

[0032] Figure 11 This is a graph showing the difference in reflectance between paper containing phosphors and paper without phosphors.

[0033] Figure 12 This is a flowchart showing the order of the determination process in Implementation Method 1.

[0034] Figure 13 This is a diagram illustrating the second processing of a variation of Embodiment 1.

[0035] Figure 14 This is a diagram used to illustrate the third process of Implementation Method 2.

[0036] Figure 15 This is a flowchart showing the order of the determination process in Implementation Method 2.

[0037] Figure 16 This is a diagram illustrating the first processing of a variation of Embodiment 2.

[0038] Figure 17 This is a flowchart showing the order of the determination process in a variation of Implementation 2.

[0039] Figure 18 This is a diagram used to illustrate the second process of Embodiment 3.

[0040] Figure 19 This is a flowchart showing the order of the determination process in Implementation Method 3.

[0041] Figure 20 This is a diagram illustrating the second processing of a variation of Embodiment 3.

[0042] Figure 21 This is a flowchart showing the order of determination and processing in a variation of Implementation Method 3.

[0043] Explanation of reference numerals: 1…Image forming apparatus; 2…Paper type identification device; 10…Control unit; 11…Processor; 12…Memory; 13…Storage; 20…Inspection unit; 21…Light source unit; 21X…First light source unit; 21Y…Second light source unit; 22…Detection unit; 23X, 23Y…Component substrate; 25…Paper guide; 26…Reflector; 27…Conveyor path; 28X, 28Y…Opening; 30…Image forming unit; 31…Intermediate transfer belt; 32…Image forming unit; 33…Transfer roller; 40…Fixing unit; 50…Scanner; 60…Operation panel; 70…Communication unit; 81…Paper supply tray; 82…Conveyor roller; 83…Paper discharge tray; 90…Bus; 131…Program; 132…Reference data; 211 X…First light-emitting element; 212X…Second light-emitting element; 213X…Third light-emitting element; 214Y…Fourth light-emitting element; 215Y…Fifth light-emitting element; 220…Light-receiving element; Bt, IRt…Transmittance; DR…Ratio difference; IRr, UVr, Vr…Reflectance; Lr, Lt, Ly, sLr…Light intensity; Lr1, Lr2, Lr3, sLr1, sLr2, sLr3…Reflected light; Lt4, Lt5…Transmitted light; Lx1…First illumination light; Lx2…Second illumination light; Lx3…Third illumination light; Ly4…Fourth illumination light; Ly5…Fifth illumination light; M…Paper; TH11, TH12…First threshold; TH21, TH22, TH23, TH24…Second threshold; TH31…Third threshold. Detailed Implementation

[0044] Hereinafter, embodiments and variations of the present invention will be described with reference to the accompanying drawings. In the following description, the same reference numerals will be used to denote the same parts and components. These names and functions are also the same. Therefore, detailed descriptions of them will not be repeated. Furthermore, the embodiments and variations described below can be selectively combined as appropriate.

[0045] [Implementation Method 1]

[0046] <A. Structure of the image forming apparatus>

[0047] Reference Figure 1 as well as Figure 2 The structure of the image forming apparatus of Embodiment 1 will be described. Figure 1 This is a diagram showing the schematic structure of the image forming apparatus according to Embodiment 1. Figure 2 This is a diagram showing the hardware structure of the image forming apparatus 1.

[0048] The image forming apparatus 1 is an MFP (Multifunction Peripheral) that forms images on paper in the form of electronic photographs. The image forming apparatus 1 includes a control unit 10, an inspection unit 20, an image forming unit 30, a fixing unit 40, a scanner 50, an operation panel 60, a communication unit 70, a paper feed tray 81, a transport roller 82, a paper discharge tray 83, a transport path 27, and a bus 90.

[0049] like Figure 2 As shown, a paper type identification device 2 for identifying paper type is constructed by a control unit 10 and an inspection unit 20. The control unit 10, inspection unit 20, image forming unit 30, fixing unit 40, scanner 50, operation panel 60, and communication unit 70 are connected by a bus 90.

[0050] The control unit 10 includes a processor 11, a memory 12, and a storage device 13. The processor 11 may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The memory 12 may be, for example, a volatile storage device such as DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory). The storage device 13 may be, for example, a non-volatile storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory.

[0051] The memory 13 stores a program 131 and reference data 132 referenced in the determination process described later. The program 131 includes computer-readable commands for controlling the image forming apparatus 1. The processor 11 implements various processes of this embodiment by expanding and executing the program 131 stored in the memory 12.

[0052] Program 131 may also be provided as part of any program, rather than as a standalone program. In this case, it cooperates with any program to implement the processing of this embodiment. Even programs that do not include such a module do not depart from the main theme of the image forming apparatus 1 of this embodiment. In addition, some or all of the functions provided by program 131 may also be implemented by dedicated hardware.

[0053] In addition, the memory 13 stores at least one of image data received from an external device and image data generated by the scanner 50.

[0054] The control unit 10 controls the various parts of the image forming apparatus 1 by executing program 131 via processor 11. For example, processor 11 operates image forming unit 30, transport roller 82, and fixing unit 40 based on image data stored in memory 13 to form an image on paper. Here, processor 11 changes the operation of the various parts related to image forming (e.g., image forming unit 30, transport roller 82, and fixing unit 40) according to the paper type determination result of paper type determination device 2. As an example, the transport speed and clamping pressure based on transport roller 82 are changed according to paper type. In addition, the heating temperature and applied pressure based on fixing unit 40 are changed according to paper type.

[0055] The inspection unit 20 is located upstream of the image forming unit 30 (between the paper supply tray 81 and the image forming unit 30) in the paper transport path 27 from the paper supply tray 81 to the paper discharge tray 83, at a position along the transport path 27. However, the position of the inspection unit 20 is not limited to this, and it can be configured at any position along the transport path 27.

[0056] The inspection unit 20 includes a light source unit 21 and a detection unit 22. The light source unit 21 illuminates light toward the transport path 27 according to the instructions of the processor 11. The detection unit 22 detects the light from the paper.

[0057] The image forming unit 30 applies toner (colorant) to paper supplied from the paper tray 81 to form an image. The image forming unit 30 includes an intermediate transfer belt 31, an image forming unit 32, and a transfer roller 33. The intermediate transfer belt 31 is an endless strip-shaped component that is wound around a plurality of rollers. The image forming unit 32 is arranged along the intermediate transfer belt 31 and forms toner images of various colors (C, M, Y, and K) on the intermediate transfer belt 31 based on image data representing an image of the printing object. As the paper passes through the clamping portion between the intermediate transfer belt 31 and the transfer roller 33, the toner images are transferred onto the paper to form an image. Furthermore, while this embodiment exemplifies an image forming unit 30 capable of forming color images, it is not limited to this; an image forming unit 30 capable of forming monochrome images may also be used.

[0058] The fixing unit 40 heats and presses the paper with the toner image transferred onto it to fix the toner image onto the paper. The fixing unit 40 includes a heating roller that holds the paper and a pair of rollers consisting of a pressure roller. The paper with the toner image fixed is conveyed by the conveying roller 82 and discharged to the paper discharge tray 83. The heating and pressing conditions of the fixing unit 40 are controlled by the processor 11 according to the type of paper.

[0059] The scanner 50 includes an optical system such as a light source and a mirror, as well as an imaging element. It reads images of paper transported along a predetermined transport path or paper placed on a platen glass, and generates image data in the form of bitmaps for each color: R (red), G (green), and B (blue). The generated image data is stored in the memory 13. By performing image formation based on this image data using the image forming unit 30, the read image can be copied onto other sheets of paper.

[0060] The operation panel 60 includes a display device such as a liquid crystal display and an input device such as a touch panel that overlaps with the screen of the display device. The operation panel 60 displays various information such as the operation status and processing results of the image forming apparatus 1 on the display device, and converts the user's input operations to the input device into operation signals and outputs them to the processor 11.

[0061] The communication unit 70 consists of a network card, etc. The communication unit 70 connects to communication networks such as LANs (Local Area Networks) and transmits and receives information with external devices on the communication network. The processor 11 communicates with external devices on the communication network via the communication unit 70.

[0062] The paper supply tray 81 holds paper before image formation. Multiple types of paper can also be stored in the paper supply tray 81.

[0063] The type of paper is characterized by at least one of the following characteristics: paper material (raw material), surface treatment state, presence or absence of phosphors, amount, and color. Therefore, papers with at least one difference in these characteristics are different types of paper. The types of paper stored in the paper supply tray 81 include, for example, ordinary paper, coated paper, recycled paper of type 1, and recycled paper of type 2.

[0064] Plain paper is made primarily from wood pulp (i.e., pulp not recycled from waste paper, but typically chemical pulp). Coated paper is paper coated on both sides. Recycled paper is paper blended from waste paper pulp at a specified ratio. Waste paper pulp readily absorbs light with peak wavelengths less than 550 nm (i.e., shorter wavelengths compared to green light).

[0065] The first type of recycled paper contains almost no phosphors, i.e., recycled paper with low phosphor content. The second type of recycled paper contains more phosphors, i.e., recycled paper with higher phosphor content. The second type of recycled paper contains more phosphors than the first type. Furthermore, the second type of recycled paper contains more phosphors than coated paper. Generally, the phosphors in paper absorb ultraviolet light and emit light with a wavelength longer than ultraviolet light (fluorescence).

[0066] The conveyor roller 82 transports a sheet of paper along the conveyor path 27 by rotating while holding the paper. The processor 11 controls the conveying timing and speed based on the conveyor roller 82, depending on the type of paper. The paper tray 83 holds the paper with the image printed on it.

[0067] <B. Structure of the Inspection Department>

[0068] Reference Figure 3 The structure of the inspection section 20 will be explained. Figure 3 This is a diagram showing an example of the structure of the inspection section 20.

[0069] Figure 3 Arrow A1 indicates the direction of paper transport M (hereinafter referred to as the "transport direction"). Arrow A2 indicates the direction perpendicular to the transport direction.

[0070] The inspection unit 20 includes a light source unit 21, a detection unit 22, component substrates 23X and 23Y, optical apertures 24X and 24Y, a paper guide 25, and a reflector 26. Paper M is conveyed along a transport path 27 disposed between the optical aperture 24X and the paper guide 25. The transport path 27 has a width in the direction of arrow A2, so the passing position of paper M can vary within this width in the direction of arrow A2.

[0071] The light source unit 21 includes a first light source unit 21X and a second light source unit 21Y. The first light source unit 21X and the detection unit 22 are located on the same side as the paper M. The first light source unit 21X includes a first light-emitting element 211X, a second light-emitting element 212X, and a third light-emitting element 213X. The first light-emitting element 211X, the second light-emitting element 212X, and the third light-emitting element 213X are, for example, LEDs (Light-Emitting Diodes). The first light-emitting element 211X illuminates light with a first wavelength, the second light-emitting element 212X illuminates light with a second wavelength, and the third light-emitting element 213X illuminates light with a third wavelength.

[0072] The light having a first wavelength has a peak wavelength of 390 nm or more and less than 550 nm. More preferably, the light having a first wavelength is light with a peak wavelength of 390 nm or more and less than 440 nm (i.e., violet light). Wavelengths of 390 nm or more and less than 440 nm are wavelengths to which the phosphors contained in the paper absorb little light, and are wavelengths to which waste paper pulp absorbs much light. As an example, in this embodiment, light with a peak wavelength of 405 nm is used as the light having a first wavelength.

[0073] The light having a second wavelength is ultraviolet light. More preferably, the peak wavelength of the light having a second wavelength is 340 nm or more and less than 390 nm. Wavelengths of 340 nm or more and less than 390 nm are the wavelengths at which the phosphor contained in the paper absorbs the most light. As an example, in this embodiment, light with a peak wavelength of 365 nm is used as the light having a second wavelength.

[0074] The light with a third wavelength is infrared light. As an example, in this embodiment, light with a peak wavelength of 850 nm is used as the light with a third wavelength.

[0075] The second light source unit 21Y is located on the side opposite to the side where the detection unit 22 is located, relative to the paper M. That is, the second light source unit 21Y, the transport path 27, and the detection unit 22 are arranged sequentially. The second light source unit 21Y includes a fourth light-emitting element 214Y and a fifth light-emitting element 215Y. Both the fourth light-emitting element 214Y and the fifth light-emitting element 215Y are LEDs. The fourth light-emitting element 214Y illuminates light with a fourth wavelength, and the fifth light-emitting element 215Y illuminates light with a fifth wavelength.

[0076] The light with the fourth wavelength is infrared light. As an example, in this embodiment, light with a peak wavelength of 850 nm is used as the light with the fourth wavelength.

[0077] The fifth wavelength of light is blue light. As an example, in this embodiment, light with a peak wavelength of 460 nm is used as the fifth wavelength of light.

[0078] During the passage of the paper through the inspection section 20, the processor 11 causes the first light-emitting element 211X, the second light-emitting element 212X, the third light-emitting element 213X, the fourth light-emitting element 214Y, and the fifth light-emitting element 215Y to emit light in a manner that the light emission timings do not overlap. The first light-emitting element 211X, the second light-emitting element 212X, the third light-emitting element 213X, the fourth light-emitting element 214Y, and the fifth light-emitting element 215Y emit light respectively, thereby illuminating the paper M conveyed in the transport path 27.

[0079] The detection unit 22 includes a light-receiving element 220. The light-receiving element 220 is, for example, a photodiode. The longer the wavelength of light, the easier it is for the photodiode to detect it. The light-receiving element 220 detects the incident light and outputs a photocurrent corresponding to the amount of incident light. The detection unit 22 converts the photocurrent output by the light-receiving element 220 into a voltage, converts the voltage into digital data, and outputs it to the processor 11.

[0080] Component substrates 23X and 23Y are positioned opposite to the paper M being transported. A first light-emitting element 211X, a second light-emitting element 212X, a third light-emitting element 213X, and a light-receiving element 220 are disposed on the surface of component substrate 23X opposite to the paper M. A fourth light-emitting element 214Y and a fifth light-emitting element 215Y are disposed on the surface of component substrate 23Y opposite to the paper M.

[0081] Optical aperture 24X is located between paper guide 25 and component substrate 23X, and optical aperture 24Y is located between paper guide 25 and component substrate 23Y. Optical aperture 24X has an opening 28X in the region including the portion opposite to the first light-emitting element 211X, the second light-emitting element 212X, the third light-emitting element 213X, and the light-receiving element 220. Optical aperture 24Y has an opening 28Y in the region including the portion opposite to the fourth light-emitting element 214Y and the fifth light-emitting element 215Y. Irradiation light from the first light source unit 21X passes through the opening 28X and enters the paper M, and illumination light from the second light source unit 21Y passes through the opening 28Y and enters the paper M. The portion of optical aperture 24X other than the opening 28X is light-blocking, and the portion of optical aperture 24Y other than the opening 28Y is light-blocking, thus suppressing light other than the illumination light from entering the paper M.

[0082] The paper guide 25 supports the paper M so that the paper M moves along the transport path 27.

[0083] The reflective portion 26 is positioned opposite the first light source unit 21X. The reflective portion 26 reflects the light irradiated from the first light source unit 21X. The reflective portion 26 is used to evaluate the reflectivity of the paper.

[0084] In addition, Figure 3 In the example shown, the second light source unit 21Y includes a fourth light-emitting element 214Y and a fifth light-emitting element 215Y. However, in embodiment 1, the second light source unit 21Y only needs to include the fourth light-emitting element 214Y, and may not include the fifth light-emitting element 215Y.

[0085] <C. Reflected Light and Reflectivity>

[0086] Reference Figure 4 as well as Figure 5 This paper explains the detection of reflected light and the calculation of reflectivity. Reflectivity is an indicator used to evaluate the reflectivity of paper.

[0087] Figure 4 This is a diagram illustrating the light detected by the light-receiving element 220 when light is irradiated from the first light source unit 21X through the inspection unit 20 at a timing.

[0088] When paper M is irradiated with a first illumination light Lx1 having a first wavelength by the first light-emitting element 211X at a timed interval by the inspection unit 20, the light-receiving element 220 detects the reflected light Lr1 as light from the paper M. The reflected light Lr1 includes the light reflected by the paper M from the first illumination light Lx1. If the paper M contains a phosphor, the reflected light Lr1 also includes the fluorescence emitted by the phosphor that has absorbed the first illumination light Lx1.

[0089] When paper M is irradiated with a second illumination light Lx2 having a second wavelength by the second light-emitting element 212X at a timing specified by the inspection unit 20, the light-receiving element 220 detects the reflected light Lr2 as light from the paper M. The reflected light Lr2 includes the light reflected by the paper M from the second illumination light Lx2. If the paper M contains a phosphor, the reflected light Lr2 also includes the fluorescence emitted by the phosphor that has absorbed the second illumination light Lx2.

[0090] When paper M is irradiated with third illumination light Lx3 having a third wavelength by the third light-emitting element 213X at a timing specified by the inspection unit 20, the light-receiving element 220 detects the reflected light Lr3 as light from paper M. The reflected light Lr3 includes the light reflected by paper M from the third illumination light Lx3. If paper M contains a phosphor, the reflected light Lr3 also includes fluorescence emitted by the phosphor that has absorbed the third illumination light Lx3.

[0091] The detection unit 22 acquires the light quantity of each of the reflected light Lr1, Lr2, and Lr3, and outputs the light quantity to the processor 11. The amount of reflected light Lr1 acquired by the detection unit 22 is an example of the "first detection value" of the present invention. The amount of reflected light Lr2 acquired by the detection unit 22 is an example of the "second detection value" of the present invention. The amount of reflected light Lr3 acquired by the detection unit 22 is an example of the "third detection value" of the present invention.

[0092] Figure 5 This is a diagram illustrating the light detected by the light-receiving element 220 when the paper M is not illuminated by light from the first light source unit 21X at the timing of the inspection section 20.

[0093] If the paper M is not irradiated with first illumination light Lx1 having a first wavelength from the first light-emitting element 211X at the timing of the inspection unit 20, the light-receiving element 220 detects the reflected light sLr1 reflected by the reflective unit 26.

[0094] If the paper M is not irradiated with second illumination light Lx2 having a second wavelength from the second light-emitting element 212X at the timing of the inspection unit 20, the light-receiving element 220 detects the reflected light sLr2 reflected by the reflective unit 26.

[0095] If the paper M is not irradiated with third illumination light Lx3 having a third wavelength from the third light-emitting element 213X at the timing of the inspection unit 20, the light-receiving element 220 detects the reflected light sLr3 reflected by the reflective unit 26.

[0096] The detection unit 22 acquires the light intensity of each of the reflected light sLr1, sLr2, and sLr3, and outputs the light intensity to the processor 11. The processor 11 stores the light intensity of each of the reflected light sLr1, sLr2, and sLr3 in the memory 13. The light intensity of each of the reflected light sLr1, sLr2, and sLr3 is an example of the reference data 132.

[0097] The reflectivity of the present invention is calculated by processor 11 using the following Equation 1.

[0098] Reflectivity = Light intensity Lr / Light intensity sLr ... (Equation 1)

[0099] The light quantity Lr in Formula 1 represents the amount of light detected by the light-receiving element 220 when the paper M is illuminated by light from the first light source unit 21X at a timing of the inspection unit 20. The light quantities of reflected light Lr1, reflected light Lr2, and reflected light Lr3 are each examples of the light quantity Lr.

[0100] The light quantity sLr in Formula 1 represents the amount of light detected by the light-receiving element 220 when the paper M is not illuminated by the first light source unit 21X at the timing of the inspection unit 20. The light quantities of reflected light sLr1, reflected light sLr2, and reflected light sLr3 are each examples of the light quantity sLr.

[0101] The reflectance Vr of light with the first wavelength, the reflectance UVr of light with the second wavelength, and the reflectance IRr of light with the third wavelength in the following description are calculated by processor 11 using the following equations 2 to 4.

[0102] The reflectivity of light with the first wavelength is Vr = (the amount of reflected light Lr1) / (the amount of reflected light sLr1) ... (Equation 2)

[0103] The reflectivity of light with the second wavelength, UVr, is given by: UVr = (amount of reflected light Lr2) / (amount of reflected light sLr2) ... (Equation 3)

[0104] The reflectivity IRr of light with a third wavelength is: (amount of reflected light Lr3) / (amount of reflected light sLr3) ... (Equation 4)

[0105] <D. Light Transmission and Transmittance>

[0106] Reference Figure 6 as well as Figure 7 This paper explains the detection of transmitted light and the calculation of transmittance. Transmittance is an indicator used to evaluate the light transmittance of paper.

[0107] Figure 6 This is a diagram illustrating the light detected by the light-receiving element 220 when light is irradiated from the second light source unit 21Y through the inspection unit 20 at a timing.

[0108] When paper M is irradiated with fourth illumination light Ly4 having a fourth wavelength by the fourth light-emitting element 214Y at a timing specified by the inspection unit 20, the light-receiving element 220 detects the transmitted light Lt4 as light from paper M. The transmitted light Lt4 includes the light transmitted through paper M in the fourth illumination light Ly4. If paper M contains a phosphor, the transmitted light Lt4 also includes the fluorescence emitted by the phosphor that has absorbed the fourth illumination light Ly4.

[0109] When paper M is irradiated with fifth illumination light Ly5 having a fifth wavelength by the fifth light-emitting element 215Y at a timed interval by the inspection unit 20, the light-receiving element 220 detects the transmitted light Lt5 as light from paper M. The transmitted light Lt5 includes the light transmitted through paper M in the fifth illumination light Ly5. If paper M contains a phosphor, the transmitted light Lt5 also includes the fluorescence emitted by the phosphor that has absorbed the fifth illumination light Ly5.

[0110] The detection unit 22 acquires the light amounts of transmitted light Lt4 and transmitted light Lt5 respectively, and outputs these light amounts to the processor 11. The amount of transmitted light Lt4 acquired by the detection unit 22 is an example of the "fourth detection value" of the present invention. The amount of transmitted light Lt5 acquired by the detection unit 22 is an example of the "fifth detection value" of the present invention.

[0111] Figure 7 This is a diagram illustrating the light detected by the light-receiving element 220 when the paper M is not illuminated by light from the second light source unit 21Y at the timing of the inspection section 20.

[0112] If the paper M is not irradiated with fourth illumination light Ly4 having a fourth wavelength from the fourth light-emitting element 214Y at the timing of the inspection unit 20, the light-receiving element 220 detects the fourth illumination light Ly4.

[0113] If the paper M is not irradiated with fifth illumination light Ly5 having a fifth wavelength from the fifth light-emitting element 215Y at the timing of the inspection unit 20, the light-receiving element 220 detects the fifth illumination light Ly5.

[0114] The detection unit 22 acquires the light intensity of the fourth illumination light Ly4 and the fifth illumination light Ly5, and outputs the light intensity to the processor 11. The processor 11 stores the light intensity of the fourth illumination light Ly4 and the fifth illumination light Ly5 in the memory 13. The light intensity of the fourth illumination light Ly4 and the fifth illumination light Ly5 is an example of the reference data 132.

[0115] The transmittance of the present invention is calculated by the processor 11 using the following formula 5.

[0116] Transmittance = Light intensity Lt / Light intensity Ly ... (Equation 5)

[0117] Equation 5 represents the amount of light detected by the light-receiving element 220 when the paper M is illuminated by light from the second light source unit 21Y at the timing of the inspection section 20. The amount of light transmitted Lt4 and the amount of light transmitted Lt5 are each examples of the amount of light Lt.

[0118] Formula 5 represents the amount of light detected by the light-receiving element 220 when the paper M is not illuminated by the second light source unit 21Y at the timing of the inspection section 20. The light amounts of the fourth illumination light Ly4 and the fifth illumination light Ly5 are each examples of the light amount Ly.

[0119] The transmittance IRt of light with the fourth wavelength and the transmittance Bt of light with the fifth wavelength described below are calculated by processor 11 using Equations 6 and 7 below.

[0120] The transmittance of light with the fourth wavelength, IRt, is given by: (amount of transmitted light Lt4) / (amount of fourth irradiation light Ly4) ... (Equation 6)

[0121] The transmittance of light with the fifth wavelength, Bt = (amount of transmitted light Lt5) / (amount of fifth irradiation light Ly5) ... (Equation 7)

[0122] <E. Paper Type Identification Process>

[0123] (E1. Paper type identification process)

[0124] Reference Figure 8 The paper type identification process of Implementation Method 1 will be explained. Figure 8 This is a flowchart illustrating the sequence of the paper type identification process in Embodiment 1. The paper type identification process includes light intensity detection processing based on the inspection unit 20 and determination processing based on the processor 11. The paper type identification process begins when paper M arrives at the inspection unit 20.

[0125] In step S1, the inspection unit 20 performs light quantity detection processing. The light quantity detection processing includes detecting the amount of reflected light Lr1, reflected light Lr2, reflected light Lr3, transmitted light Lt4, and transmitted light Lt5, and outputting the detected light quantity to the processor 11.

[0126] In step S2, the processor 11 performs a determination process. This determination process includes calculating reflectance and transmittance based on the amount of light received from the inspection unit 20, and determining the paper type based on the calculated reflectance and transmittance. After step S2, the paper type determination process ends.

[0127] (E2. Decision Processing)

[0128] Reference Figures 9-12 The determination process (step S2) will be described below. The determination process includes: a first process for determining the paper type based on the reflectance Vr of light with a first wavelength, and a second process for determining the paper type based on the reflectance UVr of light with a second wavelength.

[0129] Figure 9 This is a diagram used to illustrate the first process of Embodiment 1. Figure 9 The table shows the results of tests conducted using the inspection department 20 on various brands of recycled and coated paper. Figure 9 In the graph, the horizontal axis represents the transmittance IRt of light with the fourth wavelength, and the vertical axis represents the ratio Vr / IRr. The ratio Vr / IRr represents the ratio of the reflectance Vr of light with the first wavelength to the reflectance IRr of light with the third wavelength. The transmittance IRt is calculated using Equation 6 above. The ratio Vr / IRr is calculated using Equation 8 below.

[0130] The ratio Vr / IRr = (reflectivity Vr of light with the first wavelength) / (reflectivity IRr of light with the third wavelength) ... (Equation 8)

[0131] exist Figure 9 In the chart, the triangles represent the recycled paper ratio (Vr / IRr), and the quadrilaterals represent the coated paper ratio (Vr / IRr). For example... Figure 9 As shown, for most recycled paper, the ratio Vr / IRr is less than the first threshold TH11, while for coated paper and some recycled paper, the ratio Vr / IRr is greater than the first threshold TH11.

[0132] get Figure 9The rationale for the experimental results shown is that the waste paper pulp contained in recycled paper readily absorbs light with peak wavelengths less than 550 nm. Due to the light absorption by the waste paper pulp, recycled paper tends to have a lower reflectance (Vr) than other types of paper. Therefore, for most recycled paper, the ratio Vr / IRr is less than the first threshold TH11. On the other hand, the amount of light detected by the light-receiving element 220 increases the amount corresponding to fluorescence. Therefore, even in recycled paper containing a large amount of phosphor, the reflectance (Vr) becomes higher. Thus, for some recycled paper, the ratio Vr / IRr is greater than the first threshold TH11.

[0133] Therefore, paper types with a ratio Vr / Irr less than the first threshold TH11 can be identified as first-type recycled paper (recycled paper with fewer phosphors), and paper types with a ratio Vr / IRr greater than or equal to the first threshold TH11 can be identified as either coated paper or second-type recycled paper (recycled paper with more phosphors). The first threshold TH11, predetermined through experimentation, is stored in storage 13 and is used as a reference in the first treatment. The first threshold TH11 is an example of the reference data 132.

[0134] In the first process, the processor 11 calculates the ratio Vr / IRr and the transmittance IRt based on the amount of light obtained from the inspection unit 20, and determines whether the ratio Vr / IRr is greater than or equal to the first threshold TH11.

[0135] More specifically, the processor 11 substitutes the amount of reflected light Lr1 obtained from the inspection unit 20 and the amount of reflected light sLr1 stored in the storage 13 into Equation 2 to calculate the reflectivity Vr of light with a first wavelength. The processor 11 substitutes the amount of reflected light Lr3 obtained from the inspection unit 20 and the amount of reflected light sLr3 stored in the storage 13 into Equation 4 to calculate the reflectivity IRr of light with a third wavelength. The processor 11 substitutes the reflectivity Vr and the reflectivity IRr into Equation 8 to calculate the ratio Vr / IRr. The processor 11 substitutes the amount of transmitted light Lt4 obtained from the inspection unit 20 and the amount of fourth illumination light Ly4 stored in the storage 13 into Equation 6 to calculate the transmittance IRt of light with a fourth wavelength. The processor 11 obtains a first threshold TH11 corresponding to the transmittance IRt from the storage 13.

[0136] If the ratio Vr / IRr is less than the first threshold TH11, the processor 11 determines the paper type as the first type of recycled paper (recycled paper with few phosphors). On the other hand, if the ratio Vr / IRr is greater than or equal to the first threshold TH11, the processor 11 performs a second process to determine whether the paper type is coated paper or the second type of recycled paper (recycled paper with many phosphors).

[0137] Figure 10This is a diagram used to illustrate the second process of Embodiment 1. Figure 10 The table shows the results of tests conducted using the inspection department 20 on various brands of recycled and coated paper. Figure 10 In the graph, the horizontal axis represents the transmittance IRt of light with the fourth wavelength, and the vertical axis represents the ratio UVr / IRr. The ratio UVr / IRr represents the ratio of the reflectance UVr of light with the second wavelength to the reflectance IRr of light with the third wavelength. The transmittance IRt is calculated using Equation 6 above. The ratio UVr / IRr is calculated using Equation 9 below.

[0138] The ratio UVr / IRr = (reflectivity of light with the second wavelength UVr) / (reflectivity of light with the third wavelength IRr) ... (Equation 9)

[0139] exist Figure 10 In the chart, triangles indicate the UVr / IRr ratio of recycled paper, and quadrilaterals indicate the UVr / IRr ratio of coated paper. For example... Figure 10 As shown, for recycled paper, the ratio UVr / IRr is above the second threshold TH21, while for coated paper, the ratio UVr / IRr is less than the second threshold TH21.

[0140] Here, refer to Figure 11 To obtain Figure 10 The reasons for the experimental results shown are explained. Figure 11 This is a graph showing the difference in reflectance between paper containing phosphors and paper without phosphors. Figure 11 In the chart, the horizontal axis represents the wavelength of light shining on the paper, and the vertical axis represents the reflectivity of light.

[0141] like Figure 11 As shown, in paper without phosphors, reflectance decreases with decreasing wavelength, while in paper containing phosphors, reflectance increases with decreasing wavelength, with a boundary of approximately 400 nm. This is because the phosphors in the paper absorb ultraviolet light (light with a second wavelength) and emit light with a longer wavelength (fluorescence) that is easily detected by a photodiode, thus seemingly increasing the amount of light detected as reflected light. The increase in the amount of light detected corresponds to the amount of fluorescence; therefore, the more phosphors in the paper, the higher the apparent reflectance UVR of light with a second wavelength.

[0142] Refer again Figure 10Paper types with a UVr / IRr ratio greater than or equal to the second threshold TH21 are identified as containing more phosphors (in Embodiment 1, this is the second type of recycled paper (recycled paper with more phosphors)). Paper types with a UVr / IRr ratio less than the second threshold TH21 are identified as containing fewer phosphors (in Embodiment 1, this is coated paper). The second threshold TH21, predetermined through experimentation, is stored in storage 13 and used as a reference in the second process. The second threshold TH21 is an example of reference data 132.

[0143] In the second process, the processor 11 calculates the ratio UVr / IRr based on the amount of light obtained from the inspection unit 20, and determines whether the ratio UVr / IRr is above the second threshold TH21.

[0144] More specifically, the processor 11 substitutes the amount of reflected light Lr2 obtained from the inspection unit 20 and the amount of reflected light sLr2 stored in the storage 13 into Equation 3 to calculate the reflectivity UVr of light with the second wavelength. The processor 11 substitutes the reflectivity UVr and the reflectivity IRr calculated in the first processing into Equation 9 to calculate the ratio UVr / IRr. The processor 11 obtains the second threshold TH21 corresponding to the transmittance IRt calculated in the first processing from the storage 13.

[0145] If the ratio UVr / IRr is above the second threshold TH21, the processor 11 determines the paper type as the second type of recycled paper (recycled paper with more fluorescent particles). On the other hand, if the ratio UVr / IRr is less than the second threshold TH21, the processor 11 determines the paper type as coated paper.

[0146] Figure 12 This is a flowchart illustrating the sequence of decision-making processes in Implementation Method 1. The decision-making processes are executed by processor 11.

[0147] In step S21, processor 11 performs a first process. The first process is to determine whether the ratio Vr / IRr of the reflectance of light with a first wavelength to the reflectance IRr of light with a third wavelength is greater than or equal to a first threshold TH11 corresponding to the transmittance IRt. Through step S21, a first type of recycled paper (recycled paper with fewer phosphors) is identified.

[0148] If the ratio Vr / IRr is greater than or equal to the first threshold TH11 corresponding to the transmittance IRt ("Yes" in step S21), the processor 11 proceeds to step S22. On the other hand, if the ratio Vr / IRr is less than the first threshold TH11 corresponding to the transmittance IRt ("No" in step S21), the processor 11 proceeds to step S25.

[0149] In step S22, processor 11 performs a second process. The second process is to determine whether the ratio of the reflectance UVr of light with a second wavelength to the reflectance IRr of light with a third wavelength, UVr / IRr, is greater than or equal to a second threshold TH21 corresponding to the transmittance IRt. Through step S22, a second type of recycled paper (recycled paper with more phosphors) and coated paper are distinguished.

[0150] If the ratio UVr / IRr is greater than or equal to the second threshold TH21 corresponding to the transmittance IRt ("Yes" in step S22), the processor 11 proceeds to step S23. On the other hand, if the ratio UVr / IRr is less than the second threshold TH21 corresponding to the transmittance IRt ("No" in step S22), the processor 11 proceeds to step S24.

[0151] In step S23, processor 11 determines the paper type as the second type of recycled paper (recycled paper with more phosphors). In step S24, processor 11 determines the paper type as coated paper. In step S25, processor 11 determines the paper type as the first type of recycled paper (recycled paper with fewer phosphors).

[0152] After step S23, step S24, or step S25, the paper type identification process ends.

[0153] Thus, the paper type identification device 2 of Embodiment 1 identifies a first type of recycled paper (recycled paper with few fluorescent particles) by using a first processing method based on the amount of light detected as reflected light Lr1 (a first detection value), and identifies coated paper and a second type of recycled paper (recycled paper with many fluorescent particles) by using a second processing method based on the amount of light detected as reflected light Lr2 (a second detection value). Therefore, recycled paper can be reliably identified.

[0154] Furthermore, in the first process, instead of comparing the reflectance Vr with a threshold, the ratio of reflectance Vr to reflectance IRr is compared with a threshold, thus suppressing variations in reflectance Vr caused by changes in the passing position of the paper M. Similarly, in the second process, instead of comparing the reflectance UVr with a threshold, the ratio of reflectance UVr to reflectance IRr is compared with a threshold, thus suppressing variations in reflectance UVr caused by changes in the passing position of the paper M. It is known that the reflectance IRr of light with a third wavelength is less affected by the type of paper. Generally, when the passing position of the paper M is close to the light-receiving element 220, the light detection amount of the light-receiving element 220 increases; when the passing position of the paper M is far from the light-receiving element 220, the light detection amount of the light-receiving element 220 decreases. Therefore, reflectance Vr and reflectance UVr may vary depending on the passing position of the paper M. However, in the first process, the ratio of reflectance Vr to reflectance IRr is compared with a threshold, thus suppressing variations in reflectance Vr caused by changes in the passing position of the paper M. In addition, in the second process, the ratio of reflectance UVr to reflectance IRr is compared with a threshold, thus suppressing the variation of reflectance UVr caused by the change in the passing position of the paper M.

[0155] Alternatively, in the first process, the processor 11 may compare the reflectance Vr with a threshold predetermined by experiment to identify a first type of recycled paper (recycled paper with fewer phosphors).

[0156] Alternatively, in the second process, the processor 11 may compare the reflectance UVR with a threshold predetermined by experiment to identify a second type of recycled paper (recycled paper with more phosphors).

[0157] Furthermore, as mentioned above, it is sufficient for the peak wavelength of the light having the first wavelength to be 390 nm or more and less than 550 nm. However, by using light with a peak wavelength of 390 nm or more and less than 440 nm (i.e., violet light) as the light having the first wavelength, the accuracy of the paper type discrimination based on the first treatment is improved. This is because wavelengths of 390 nm or more and less than 440 nm are wavelengths where the phosphors contained in the paper absorb little light, and are wavelengths where waste paper pulp absorbs much light. Therefore, the reflectance Vr tends to differ between cases where the paper type is recycled paper of the first type (recycled paper with few phosphors) and cases where it is not.

[0158] Furthermore, as mentioned above, any light with a second wavelength can be ultraviolet light. However, by using light with a peak wavelength of 340 nm or more but less than 390 nm as the light with a second wavelength, the accuracy of paper type discrimination based on the second treatment is improved. This is because wavelengths of 340 nm or more but less than 390 nm are the wavelengths at which the phosphors contained in the paper absorb the most light. Therefore, the reflectance UVr is easily different between paper types that contain more phosphors (in Embodiment 1, the second type of recycled paper (recycled paper with more phosphors)) and paper types that do not contain such phosphors.

[0159] [Modification of Implementation Method 1]

[0160] As a second process, the processor 11 can also distinguish between a second type of recycled paper (recycled paper with more phosphors) and coated paper based on the difference between the ratio of the reflectance Vr of light with a first wavelength to the reflectance IRr of light with a third wavelength and the ratio of the reflectance UVr of light with a second wavelength to the reflectance IRr of light with a third wavelength.

[0161] Figure 13 This is a diagram illustrating the second processing step in a variation of Embodiment 1. Figure 13 The results of tests conducted using the inspection department 20 on various brands of recycled and coated paper are presented. Figure 13 In the graph, the horizontal axis represents the transmittance IRt of light with the fourth wavelength, and the vertical axis represents the ratio difference DR. The ratio difference DR represents the difference between the ratio of the reflectance Vr of light with the first wavelength to the reflectance IRr of light with the third wavelength and the ratio of the reflectance UVr of light with the second wavelength to the reflectance IRr of light with the third wavelength. The transmittance IRt is calculated using Equation 6 above. The ratio difference DR is calculated using Equation 10 below.

[0162] Ratio difference DR = (Ratio Vr / IRr) - (Ratio UVr / IRr) ... (Equation 10)

[0163] exist Figure 13 In the chart, triangles represent the ratio difference (DR) of recycled paper, and quadrilaterals represent the ratio difference (DR) of coated paper. For example... Figure 13 As shown, for coated paper, the ratio difference DR is above the second threshold TH22, while for recycled paper, the ratio difference DR is less than the second threshold TH22.

[0164] get Figure 13The rationale behind the experimental results is that the phosphors contained in the paper absorb ultraviolet light (light with a second wavelength) and emit light with a longer wavelength (fluorescence) that is easily detected by a photodiode, thus apparently increasing the amount of light detected as reflected light. The increase in the amount of light detected corresponds to the amount of fluorescence, therefore there is a trend that the more phosphors contained in the paper, the higher the apparent reflectance (UVr) of the second wavelength light. Therefore, the ratio difference (DR) of paper types containing more phosphors is less than the second threshold (TH22).

[0165] Therefore, paper types with a ratio difference DR less than the second threshold TH22 can be identified as paper types containing more phosphors (in a variation of Embodiment 1, this is the second type of recycled paper (recycled paper with more phosphors)). The second threshold TH22, determined experimentally in advance, is stored in the storage device 13 and is referenced in the second process. The second threshold TH22 is an example of the reference data 132.

[0166] In the second process, processor 11 calculates the ratio difference DR and determines whether the ratio difference DR is above the second threshold TH22.

[0167] More specifically, processor 11 calculates the ratio Vr / IRr and the ratio UVr / IRr using the method described above, and substitutes the ratio Vr / IRr and the ratio UVr / IRr into Equation 10 to calculate the ratio difference DR. Processor 11 retrieves the second threshold TH22 corresponding to the transmittance IRt calculated in the first process from memory 13.

[0168] If the ratio difference DR is greater than or equal to the second threshold TH22, the processor 11 determines the paper type as coated paper. On the other hand, if the ratio difference DR is less than the second threshold TH22, the processor 11 determines the paper type as the second type of recycled paper (recycled paper with more fluorescent particles).

[0169] Thus, in the second process, not only the reflectivity UVr of light with the second wavelength is considered, but also the reflectivity Vr of light with the first wavelength is considered to determine the paper type, thereby further improving the accuracy of paper type determination.

[0170] In addition, instead of comparing the difference between reflectance Vr and reflectance UVr with a threshold, the difference between the ratio of reflectance Vr to reflectance IRr and the ratio of reflectance UVr to reflectance IRr with a threshold is compared. Therefore, it is possible to suppress the variation of reflectance Vr and reflectance UVr caused by the change in the passing position of the paper M.

[0171] Alternatively, in the second process, the processor 11 may identify a second type of recycled paper (recycled paper with more fluorescent particles) by comparing the difference between reflectance Vr and reflectance UVr with a threshold predetermined by experiment.

[0172] [Implementation Method 2]

[0173] In Embodiment 1, the distinction between the first type of recycled paper (recycled paper with few phosphors), the second type of recycled paper (recycled paper with many phosphors), and coated paper was described. In Embodiment 2, the distinction between the first type of recycled paper (recycled paper with few phosphors), the second type of recycled paper (recycled paper with many phosphors), coated paper, and ordinary paper was described. The image forming apparatus of Embodiment 2 is the same as the image forming apparatus 1 of Embodiment 1, therefore, the same reference numerals are used to label the same structures without repeating the description. Furthermore, in Embodiment 1, the second light source unit 21Y may not include the fifth light-emitting element 215Y, but in Embodiment 2, the second light source unit 21Y must include the fifth light-emitting element 215Y.

[0174] Since the difference between Embodiment 2 and Embodiment 1 lies in the determination process, the determination process of Embodiment 2 will be described here, and other processes will not be described again. The determination process of Embodiment 2 includes the first and second processes described above, as well as a third process. The third process determines the type of ordinary paper based on the transmittance IRt of light with a fourth wavelength and the transmittance Bt of light with a fifth wavelength.

[0175] Figure 14 This is a diagram used to illustrate the third process of Embodiment 2. Figure 14 The report indicates the results of tests conducted by the Inspection Department 20 on various brands of recycled paper, coated paper, and ordinary paper. Figure 14 In the graph, the horizontal axis represents the transmittance IRt of light with the fourth wavelength, and the vertical axis represents the transmittance Bt of light with the fifth wavelength. The transmittance IRt and transmittance Bt are calculated using Equations 6 and 7 above, respectively.

[0176] exist Figure 14 In the chart, triangles represent the transmittance (Bt) of recycled paper, quadrilaterals represent the transmittance (Bt) of coated paper, and circles represent the transmittance (Bt) of plain paper. For example... Figure 14 As shown, for most ordinary paper, the transmittance Bt is above the third threshold TH31, while for most coated paper and most recycled paper, the transmittance Bt is less than the third threshold TH31.

[0177] Therefore, paper types with a transmittance Bt greater than or equal to the third threshold TH31 can be classified as ordinary paper, while paper types with a transmittance Bt less than the third threshold TH31 can be classified as either coated paper or recycled paper. The third threshold TH31, predetermined through experimentation, is stored in storage 13 and is used as a reference in the third treatment. The third threshold TH31 is an example of the reference data 132.

[0178] In the third process, the processor 11 calculates the transmittance IRt and transmittance Bt based on the amount of light obtained from the inspection unit 20, and determines whether the transmittance Bt is above the third threshold TH31.

[0179] More specifically, the processor 11 substitutes the amount of transmitted light Lt4 obtained from the inspection unit 20 and the amount of fourth illumination light Ly4 stored in the storage 13 into Equation 6 to calculate the transmittance IRt of light with a fourth wavelength. The processor 11 substitutes the amount of transmitted light Lt5 obtained from the inspection unit 20 and the amount of fifth illumination light Ly5 stored in the storage 13 into Equation 7 to calculate the transmittance Bt of light with a fifth wavelength. The processor 11 obtains a third threshold TH31 corresponding to the transmittance IRt from the storage 13.

[0180] When the transmittance Bt is above the third threshold TH31, the processor 11 classifies the paper type as ordinary paper. On the other hand, when the transmittance Bt is below the third threshold TH31, the processor 11 performs a first process to determine whether the paper type is coated paper or recycled paper. If the paper type cannot be determined by the first process, that is, when the ratio Vr / IRr is above the first threshold TH11, the processor 11 performs a second process to determine whether the paper type is coated paper or a second type of recycled paper (recycled paper with more fluorescent particles).

[0181] Figure 15 This is a flowchart illustrating the sequence of decision-making processes in Implementation Method 2. The decision-making processes are executed by processor 11. Figure 15 In the determination and processing shown, for Figure 12 The determination process shown includes additional steps S31 and S32. Figure 15 In the determination process shown, for the case of... Figure 12 Processes that are identical in the shown steps are labeled with the same step number and will not be described repeatedly.

[0182] In step S31, processor 11 performs a third process. The third process is to determine whether the transmittance Bt is above the third threshold TH31 corresponding to the transmittance IRt. Ordinary paper is identified through step S31.

[0183] If the transmittance Bt is greater than or equal to the third threshold TH31 corresponding to the transmittance IRt ("Yes" in step S31), the processor 11 proceeds to step S32. On the other hand, if the transmittance Bt is less than the third threshold TH31 corresponding to the transmittance IRt ("No" in step S31), the processor 11 proceeds to step S21.

[0184] In step S32, the processor 11 determines the paper type as ordinary paper. After steps S23, S24, S25, or S32, the paper type determination process ends.

[0185] Thus, the paper type identification device 2 of Embodiment 2 identifies a first type of recycled paper (recycled paper with few fluorescent particles) by using a first processing method based on the amount of light detected as reflected light Lr1 (a first detection value), and identifies coated paper and a second type of recycled paper (recycled paper with many fluorescent particles) by using a second processing method based on the amount of light detected as reflected light Lr2 (a second detection value). Therefore, recycled paper can be reliably identified.

[0186] Furthermore, the paper type identification device 2 of Embodiment 2 can further identify ordinary paper by using a third process that measures the amount of transmitted light Lt4 (fourth detection value) and the amount of transmitted light Lt5 (fifth detection value).

[0187] [Modification of Implementation Method 2]

[0188] exist Figure 15 In the determination process shown, the third process, the first process, and the second process are performed in sequence, or the first process, the third process, and the second process can be performed in sequence.

[0189] Figure 16 This is a diagram illustrating the first processing step of a variation of Embodiment 2. Figure 16 The report indicates the results of tests conducted by the Inspection Department 20 on various brands of recycled paper, coated paper, and ordinary paper. Figure 16 In the graph, the horizontal axis represents the transmittance IRt of light with the fourth wavelength, and the vertical axis represents the ratio (Vr / IRr) of the reflectance Vr of light with the first wavelength to the reflectance IRr of light with the third wavelength. The transmittance IRt is calculated using Equation 6 above. The ratio Vr / IRr is calculated using Equation 8 above.

[0190] exist Figure 16 In the chart, triangles represent the recycled paper ratio (Vr / IRr), quadrilaterals represent the coated paper ratio (Vr / IRr), and circles represent the uncoated paper ratio (Vr / IRr). For example... Figure 16As shown, for most recycled paper, the ratio Vr / IRr is less than the first threshold TH12, while for most coated paper, most ordinary paper, and some recycled paper, the ratio Vr / IRr is greater than the first threshold TH12.

[0191] get Figure 16 The reasons for and the results shown in the experiment Figure 9 The reasons given for the experimental results are the same.

[0192] Therefore, paper types with a ratio Vr / IRr less than the first threshold TH12 can be identified as the first type of recycled paper (recycled paper with fewer phosphors), and paper types with a ratio Vr / IRr greater than or equal to the first threshold TH12 can be identified as either coated paper, plain paper, or the second type of recycled paper (recycled paper with more phosphors). The first threshold TH12, predetermined experimentally, is stored in storage 13 and is used as a reference in the first treatment. The first threshold TH12 is an example of the reference data 132.

[0193] In the first process, the processor 11 calculates the ratio Vr / IRr and the transmittance IRt based on the light quantity obtained from the inspection unit 20 using the method described above, and determines whether the ratio Vr / IRr is greater than or equal to the first threshold TH12. More specifically, the processor 11 obtains the first threshold TH12 corresponding to the transmittance IRt from the storage unit 13, and determines whether the ratio Vr / IRr is greater than or equal to the first threshold TH12.

[0194] If the ratio Vr / IRr is less than the first threshold TH12, the processor 11 classifies the paper type as the first type of recycled paper (recycled paper with fewer phosphors). On the other hand, if the ratio Vr / IRr is greater than or equal to the first threshold TH12, the processor 11 performs a third process to determine whether the paper type is coated paper, plain paper, or the second type of recycled paper (recycled paper with more phosphors). If the third process cannot determine the paper type, i.e., if the transmittance Bt is less than the third threshold TH31, the processor 11 performs a second process to determine whether the paper type is coated paper or the second type of recycled paper (recycled paper with more phosphors).

[0195] Figure 17 This is a flowchart illustrating the sequence of decision-making processes in a modified example of Implementation Method 2. The decision-making processes are executed by processor 11. Figure 17 The determination and processing shown Figure 15 In the shown decision-making process, the order of the first, second, and third processes is different. Figure 17 In the shown decision-making process, the first process, the third process, and the second process are performed sequentially. Additionally, in... Figure 17In the determination process shown, step S21A is performed as the first process, replacing step S21. Figure 17 In the determination process shown, for the case of... Figure 15 Processes that are identical in the shown steps are labeled with the same step number and will not be described repeatedly.

[0196] In step S21A, processor 11 performs a first process. The first process is to determine whether the ratio Vr / IRr of the reflectance of light with a first wavelength to the reflectance IRr of light with a third wavelength is greater than or equal to a first threshold TH12 corresponding to the transmittance IRt. Through step S21A, a first type of recycled paper (recycled paper with fewer phosphors) is identified.

[0197] If the ratio Vr / IRr is greater than or equal to the first threshold TH12 corresponding to the transmittance IRt ("Yes" in step S21A), the processor 11 proceeds to step S31. On the other hand, if the ratio Vr / IRr is less than the first threshold TH12 corresponding to the transmittance IRt ("No" in step S21A), the processor 11 proceeds to step S25.

[0198] After step S23, step S24, step S25, or step S32, the paper type identification process ends.

[0199] Thus, the paper type identification device 2 of the modified embodiment 2 also identifies the first type of recycled paper (recycled paper with few fluorescent particles) through the first process, and identifies the coated paper and the second type of recycled paper (recycled paper with many fluorescent particles) through the second process. Therefore, recycled paper can be reliably identified.

[0200] Furthermore, the paper type identification device 2 of the modified embodiment 2 can further identify ordinary paper through a third process.

[0201] [Implementation Method 3]

[0202] In Embodiment 2, the distinction between the first type of recycled paper (recycled paper with few phosphors), the second type of recycled paper (recycled paper with many phosphors), coated paper, and ordinary paper was described. In Embodiment 3, the distinction between the first type of recycled paper (recycled paper with few phosphors), the second type of recycled paper (recycled paper with many phosphors), coated paper, ordinary paper with few phosphors, and ordinary paper with many phosphors was described. The image forming apparatus of Embodiment 3 is the same as the image forming apparatus 1 of Embodiment 2; therefore, the same reference numerals are used to label the same structures without repeating the description.

[0203] The difference between Embodiment 3 and Embodiment 2 lies in the determination process. Therefore, the determination process of Embodiment 3 will be described here, and other processes will not be described again. The determination process of Embodiment 3 also includes a first process, a second process, and a third process, but the execution order and number of executions of the first process, the second process, and the third process are different in the determination process of Embodiment 3 compared with the determination process of Embodiment 2.

[0204] Figure 18 This is a diagram used to illustrate the second process of Embodiment 3. Figure 18 The report indicates the results of tests conducted by the Inspection Department 20 on various brands of recycled paper, coated paper, and ordinary paper. Figure 18 In the graph, the horizontal axis represents the transmittance IRt of light with the fourth wavelength, and the vertical axis represents the ratio of the reflectance UVr of light with the second wavelength to the reflectance IRr of light with the third wavelength (the ratio UVr / IRr). The transmittance IRt is calculated using Equation 6 above. The ratio UVr / IRr is calculated using Equation 9 above.

[0205] exist Figure 18 In the chart, triangles indicate the ratio of recycled paper (UVr / IRr), quadrilaterals indicate the ratio of coated paper (UVr / IRr), and circles indicate the ratio of uncoated paper (UVr / IRr). For example... Figure 18 As shown, for coated paper, the ratio UVr / IRr is less than the second threshold TH23.

[0206] As described above, there is a trend that the more phosphors a paper contains, the higher its apparent reflectance (UVr) of the second wavelength of light. Therefore, paper types with a UVr / IRr ratio of TH23 or higher can be identified as paper types containing more phosphors (in Embodiment 3, this includes second-type recycled paper (recycled paper with more phosphors) and ordinary paper with more phosphors), while paper types with a UVr / IRr ratio less than the second threshold TH23 can be identified as paper types with fewer phosphors (in Embodiment 3, this includes coated paper, first-type recycled paper (recycled paper with fewer phosphors), and ordinary paper with fewer phosphors). The second threshold TH23, determined in advance through experiments, is stored in storage 13 and used as a reference in the second process. The second threshold TH23 is an example of reference data 132.

[0207] In the second process, the processor 11 calculates the ratio UVr / IRr based on the light quantity obtained from the inspection unit 20 using the method described above, and determines whether the ratio UVr / IRr is greater than or equal to the second threshold TH23. More specifically, the processor 11 obtains the second threshold TH23 corresponding to the transmittance IRt from the storage unit 13, and determines whether the ratio UVr / IRr is greater than or equal to the second threshold TH23.

[0208] If the ratio UVr / IRr is above the second threshold TH23, the processor 11 determines that the paper type is either the second type of recycled paper (recycled paper with more phosphors) or ordinary paper with more phosphors, and further performs the third process to distinguish between the second type of recycled paper (recycled paper with more phosphors) and ordinary paper with more phosphors.

[0209] On the other hand, if the ratio Vr / IRr is less than the second threshold TH23, the processor 11 determines that the paper type is any one of the first type of recycled paper (recycled paper with few phosphors), coated paper, and ordinary paper with few phosphors, and further performs the first process. If the paper type cannot be determined by the first process, that is, if the ratio Vr / IRr is greater than or equal to the first threshold TH11, the processor 11 further performs the third process in order to determine whether the paper type is coated paper or ordinary paper with few phosphors.

[0210] Figure 19 This is a flowchart illustrating the sequence of decision-making processes in Implementation Method 3. The decision-making processes are executed by processor 11. Figure 19 The determination and processing shown Figure 15 In the shown decision-making process, the execution order and number of executions of the first, second, and third processes are different. Additionally, in... Figure 19 In the determination process shown, as a second process, step S22A is performed instead of step S22; as a third process, steps S31A and S31B are performed instead of step S31. Figure 19 In the determination process shown, for the case of... Figure 15 Processes that are identical in the shown steps are labeled with the same step number and will not be described repeatedly.

[0211] In step S22A, processor 11 performs a second process. This second process determines whether the ratio of the reflectance UVr of light with a second wavelength to the reflectance IRr of light with a third wavelength, UVr / IRr, is greater than or equal to a second threshold TH23 corresponding to the transmittance IRt. Through step S22A, paper with more phosphors and paper with fewer phosphors are distinguished.

[0212] If the ratio UVr / IRr is greater than or equal to the second threshold TH23 corresponding to the transmittance IRt ("Yes" in step S22A), the processor 11 proceeds to step S31A. On the other hand, if the ratio UVr / IRr is less than the second threshold TH23 corresponding to the transmittance IRt ("No" in step S22A), the processor 11 proceeds to step S21.

[0213] In step S31A, processor 11 performs a third process. The third process is to determine whether the transmittance Bt is above the third threshold TH31 corresponding to the transmittance IRt. Through step S31A, plain paper and other types of paper are identified.

[0214] If the transmittance Bt is greater than or equal to the third threshold TH31 corresponding to the transmittance IRt ("Yes" in step S31A), the processor 11 proceeds to step S32A. On the other hand, if the transmittance Bt is less than the third threshold TH31 corresponding to the transmittance IRt ("No" in step S31A), the processor 11 proceeds to step S23.

[0215] If the ratio Vr / IRr is above the first threshold TH11 corresponding to the transmittance IRt ("Yes" in step S21), the processor 11 causes the process to proceed to step S31B.

[0216] In step S31B, processor 11 performs a third process. The third process is to determine whether the transmittance Bt is above the third threshold TH31 corresponding to the transmittance IRt. Through step S31B, plain paper and other types of paper are identified.

[0217] If the transmittance Bt is greater than or equal to the third threshold TH31 corresponding to the transmittance IRt ("Yes" in step S31B), the processor 11 proceeds to step S32B. On the other hand, if the transmittance Bt is less than the third threshold TH31 corresponding to the transmittance IRt ("No" in step S31B), the processor 11 proceeds to step S24.

[0218] In step S32A, processor 11 determines the paper type as ordinary paper with many fluorescent particles. In step S32B, processor 11 determines the paper type as ordinary paper with few fluorescent particles.

[0219] After steps S23, S24, S25, S32A, or S32B, the paper type identification process ends.

[0220] Thus, the paper type identification device 2 of Embodiment 3, through the second and third processes, distinguishes between the second type of recycled paper (recycled paper with more fluorescent particles) and ordinary paper with more fluorescent particles. Furthermore, the paper type identification device 2 of Embodiment 3, through the second and first processes, distinguishes between the first type of recycled paper (recycled paper with fewer fluorescent particles). Additionally, the paper type identification device 2 of Embodiment 3, through the second, first, and third processes, distinguishes between coated paper and ordinary paper with fewer fluorescent particles. Therefore, recycled paper can be reliably identified.

[0221] [Modification of Implementation Method 3]

[0222] As a second process, the processor 11 may also determine the paper with more phosphors based on the difference between the ratio of the reflectance Vr of light with a first wavelength to the reflectance IRr of light with a third wavelength and the ratio of the reflectance UVr of light with a second wavelength to the reflectance IRr of light with a third wavelength.

[0223] Figure 20 This is a diagram illustrating the second processing step in a variation of Embodiment 3. Figure 20 The report indicates the results of tests conducted by the Inspection Department 20 on various brands of recycled paper, coated paper, and ordinary paper. Figure 20 In the graph, the horizontal axis represents the transmittance IRt of light with the fourth wavelength, and the vertical axis represents the difference (ratio difference DR) between the ratio of reflectance Vr of light with the first wavelength to the reflectance IRr of light with the third wavelength and the ratio of reflectance UVr of light with the second wavelength to the reflectance IRr of light with the third wavelength. The transmittance IRt is calculated using Equation 6 above. The ratio difference DR is calculated using Equation 10 above.

[0224] exist Figure 20 In the chart, triangles represent the ratio difference (DR) of recycled paper, quadrilaterals represent the ratio difference (DR) of coated paper, and circles represent the ratio difference (DR) of unrecycled paper. For example... Figure 20 As shown, for coated paper, the ratio difference DR is above the second threshold TH24.

[0225] As described above, there is a trend that the more phosphors a paper contains, the higher its apparent reflectance Upr of light of the second wavelength. Therefore, paper types with a ratio difference DR less than the second threshold TH24 can be identified as paper types containing more phosphors (in a variation of Embodiment 3, this includes second-type recycled paper (recycled paper with more phosphors) and ordinary paper with more phosphors), while paper types with a ratio difference DR greater than or equal to the second threshold TH24 can be identified as paper types with fewer phosphors (in a variation of Embodiment 3, this includes coated paper, first-type recycled paper (recycled paper with fewer phosphors), and ordinary paper with fewer phosphors). The second threshold TH24, determined in advance through experiments, is stored in storage 13 and used as a reference in the second process. The second threshold TH24 is an example of reference data 132.

[0226] In the second process, the processor 11 calculates the ratio difference DR based on the light quantity obtained from the inspection unit 20 using the method described above, and determines whether the ratio difference DR is greater than or equal to the second threshold TH24. More specifically, the processor 11 obtains the second threshold TH24 corresponding to the transmittance IRt from the storage unit 13, and determines whether the ratio difference DR is greater than or equal to the second threshold TH24.

[0227] If the ratio difference DR is less than the second threshold TH24, the processor 11 determines that the paper type is either the second type of recycled paper (recycled paper with more fluorescent particles) or ordinary paper with more fluorescent particles, and further performs the third process to distinguish between the second type of recycled paper (recycled paper with more fluorescent particles) and ordinary paper with more fluorescent particles.

[0228] On the other hand, if the ratio difference DR is greater than or equal to the second threshold TH24, the processor 11 determines that the paper type is any one of the first type of recycled paper (recycled paper with few phosphors), coated paper, and ordinary paper with few phosphors, and further performs the first process. If the paper type cannot be determined by the first process, that is, if the ratio Vr / IRr is greater than or equal to the first threshold TH11, the processor 11 further performs the third process in order to determine whether the paper type is coated paper or ordinary paper with few phosphors.

[0229] Figure 21 This is a flowchart illustrating the sequence of decision-making processes in a modified example of Embodiment 3. The decision-making processes are executed by processor 11. Figure 21 In the determination process shown, step S22B is performed as a second process, replacing step S22A. Figure 21 In the determination process shown, for the case with Figure 19 Processes that are identical in the shown steps are labeled with the same step number and will not be described repeatedly.

[0230] In step S22B, processor 11 performs a second process. This second process determines whether the ratio difference DR is greater than or equal to the second threshold TH24 corresponding to the transmittance IRt. Step S22B distinguishes between papers with more phosphors and papers with fewer phosphors.

[0231] If the ratio difference DR is greater than or equal to the second threshold TH24 corresponding to the transmittance IRt ("Yes" in step S22B), the processor 11 causes the process to proceed to step S21. On the other hand, if the ratio difference DR is less than the second threshold TH24 corresponding to the transmittance IRt ("No" in step S22B), the processor 11 causes the process to proceed to step S31A.

[0232] Thus, the paper type identification device 2 of Embodiment 3, through the second and third processes, distinguishes between the second type of recycled paper (recycled paper with more fluorescent particles) and ordinary paper with more fluorescent particles. Furthermore, the paper type identification device 2 of Embodiment 3, through the second and first processes, distinguishes between the first type of recycled paper (recycled paper with fewer fluorescent particles). Additionally, the paper type identification device 2 of Embodiment 3, through the second, first, and third processes, distinguishes between coated paper and ordinary paper with fewer fluorescent particles. Therefore, recycled paper can be reliably identified.

[0233] The embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. The scope of the invention is defined not by the foregoing description but by the claims, and is intended to include all modifications within the scope of the claims.

Claims

1. A paper type identification device, comprising: The first light source unit illuminates the paper with light having a first wavelength and light having a second wavelength. The detection unit detects light from the paper and obtains a detection value based on the amount of light. as well as The control unit uses the detected values ​​to derive a determination result for the type of paper. The first light source unit and the detection unit are located on the same side relative to the paper. The detection value includes: a first detection value based on the amount of light from the paper when the paper is irradiated with light having the first wavelength; And a second detection value based on the amount of light from the paper when light of the second wavelength is irradiated onto the paper. The control unit: The first type of recycled paper is determined by using the first processing of the first detection value; and By using a second processing step on the second detection value, a second type of recycled paper, different from the first type of recycled paper, is identified. The second type of recycled paper contains more phosphors compared to the first type of recycled paper.

2. The paper type identification device according to claim 1, wherein, Light with the second wavelength is ultraviolet light. The second process includes using the second detection value to distinguish between coated paper and the second type of recycled paper.

3. The paper type identification device according to claim 2, wherein, The first light source unit also irradiates the paper with light having a third wavelength. The detection value also includes a third detection value based on the amount of light from the paper when light with the third wavelength is shone onto the paper. The second process includes: Calculate reflectance based on the second detected value; Calculate reflectance based on the third detection value; and The coated paper and the second type of recycled paper are distinguished based on the ratio of reflectance calculated based on the second detection value to reflectance calculated based on the third detection value.

4. The paper type identification device according to claim 3, wherein, The light with the third wavelength is infrared light.

5. The paper type identification device according to claim 1, wherein, Light with the second wavelength is ultraviolet light. The second process includes using the second detection value and the first detection value to distinguish between coated paper and the second type of recycled paper.

6. The paper type identification device according to claim 5, wherein, The first light source unit also irradiates the paper with light having a third wavelength. The detection value also includes a third detection value based on the amount of light from the paper when light with the third wavelength is shone onto the paper. The second process includes: Calculate reflectance based on the first detected value; Calculate reflectance based on the second detected value; Calculate reflectance based on the third detection value; and The coated paper and the second type of recycled paper are distinguished based on the ratio of reflectance calculated based on the first detection value to reflectance calculated based on the third detection value, and the ratio of reflectance calculated based on the second detection value to reflectance calculated based on the third detection value.

7. The paper type identification device according to claim 6, wherein, The light with the third wavelength is infrared light.

8. The paper type identification device according to claim 1, wherein, The peak wavelength of the light having the first wavelength is greater than 390 nm and less than 550 nm. The first process includes using the first detection value to identify the first type of recycled paper.

9. The paper type identification device according to claim 8, wherein, The first light source unit also irradiates the paper with light having a third wavelength. The detection value also includes a third detection value based on the amount of light from the paper when light with the third wavelength is shone onto the paper. The first process includes: Calculate reflectance based on the first detected value; Calculate reflectance based on the third detection value; and The first type of recycled paper is identified based on the ratio of reflectance calculated based on the first detection value to reflectance calculated based on the third detection value.

10. The paper type identification device according to claim 9, wherein, The light with the third wavelength is infrared light.

11. The paper type identification device according to any one of claims 1 to 10, wherein, The peak wavelength of the light having the first wavelength is greater than 390 nm and less than 440 nm. The peak wavelength of the light having the second wavelength is above 340 nm and below 390 nm.

12. The paper type identification device according to claim 1, wherein, The paper type identification device also includes a second light source unit, which is located on the side opposite to the side where the detection unit is located, relative to the paper. The second light source unit also illuminates the paper with light having a fourth wavelength and light having a fifth wavelength. The detection values ​​further include: a fourth detection value based on the amount of light from the paper when the paper is irradiated with light having the fourth wavelength; and a fifth detection value based on the amount of light from the paper when the paper is irradiated with light having the fifth wavelength. The control unit also uses a third processing method based on the fourth and fifth detection values ​​to distinguish ordinary paper.

13. The paper type identification device according to claim 12, wherein, The light with the fourth wavelength is infrared light, and the light with the fifth wavelength is blue light.

14. A method for identifying paper type, comprising: Light with a first wavelength and light with a second wavelength are shone toward the paper; Detect the light from the paper and obtain a detection value based on the amount of light. as well as Using the detected values, the determination result of the paper type is derived. The location where light with the first wavelength is generated, the location where light with the second wavelength is generated, and the detection location of light from the paper are located on the same side relative to the paper. The detection values ​​include: a first detection value based on the amount of light from the paper when the paper is irradiated with light having the first wavelength; and a second detection value based on the amount of light from the paper when the paper is irradiated with light having the second wavelength. The results of determining the type of paper are as follows: The first type of recycled paper is determined by using the first processing of the first detection value; and By using a second processing step on the second detection value, a second type of recycled paper, different from the first type of recycled paper, is identified. The second type of recycled paper contains more phosphors compared to the first type of recycled paper.

15. The paper type identification method according to claim 14, wherein, Light with the second wavelength is ultraviolet light. The second process includes using the second detection value to distinguish between coated paper and the second type of recycled paper.

16. The paper type identification method according to claim 15, wherein, During the irradiation, light with a third wavelength is also irradiated toward the paper. The detection value also includes a third detection value based on the amount of light from the paper when light with the third wavelength is shone onto the paper. The second process includes: Calculate reflectance based on the second detected value; Calculate reflectance based on the third detection value; and The coated paper and the second type of recycled paper are distinguished based on the ratio of reflectance calculated based on the second detection value to reflectance calculated based on the third detection value.

17. The paper type identification method according to claim 16, wherein, The light with the third wavelength is infrared light.

18. The paper type identification method according to claim 14, wherein, Light with the second wavelength is ultraviolet light. The second process includes using the second detection value and the first detection value to distinguish between coated paper and the second type of recycled paper.

19. The paper type identification method according to claim 18, wherein, During the irradiation, light with a third wavelength is also irradiated toward the paper. The detection value also includes a third detection value based on the amount of light from the paper when light with the third wavelength is shone onto the paper. The second process includes: Calculate reflectance based on the first detected value; Calculate reflectance based on the second detected value; Calculate reflectance based on the third detection value; and The coated paper and the second type of recycled paper are distinguished based on the ratio of reflectance calculated based on the first detection value to reflectance calculated based on the third detection value, and the ratio of reflectance calculated based on the second detection value to reflectance calculated based on the third detection value.

20. The paper type identification method according to claim 19, wherein, The light with the third wavelength is infrared light.

21. The paper type identification method according to claim 14, wherein, The peak wavelength of the light having the first wavelength is greater than 390 nm and less than 550 nm. The first process includes using the first detection value to identify the first type of recycled paper.

22. The paper type identification method according to claim 21, wherein, During the irradiation, light with a third wavelength is also irradiated toward the paper. The detection value also includes a third detection value based on the amount of light from the paper when light with the third wavelength is shone onto the paper. The first process includes: Calculate reflectance based on the first detected value; Calculate reflectance based on the third detection value; and The first type of recycled paper is identified based on the ratio of reflectance calculated based on the first detection value to reflectance calculated based on the third detection value.

23. The paper type identification method according to claim 22, wherein, The light with the third wavelength is infrared light.

24. The paper type identification method according to any one of claims 14 to 23, wherein, The peak wavelength of the light having the first wavelength is greater than 390 nm and less than 440 nm. The peak wavelength of the light having the second wavelength is above 340 nm and below 390 nm.

25. The paper type identification method according to claim 14, wherein, The paper type identification method further includes irradiating the paper with light having a fourth wavelength and light having a fifth wavelength. The positions where light with the fourth wavelength is generated and the positions where light with the fifth wavelength is generated are located on opposite sides of the detection position of light from the paper relative to the paper. The detection values ​​further include: a fourth detection value based on the amount of light from the paper when the paper is irradiated with light having the fourth wavelength; and a fifth detection value based on the amount of light from the paper when the paper is irradiated with light having the fifth wavelength. In the process of determining the type of paper, a third processing step is performed using the fourth and fifth detection values ​​to identify ordinary paper.

26. The paper type identification method according to claim 25, wherein, The light with the fourth wavelength is infrared light, and the light with the fifth wavelength is blue light.

27. A computer-readable recording medium, wherein, The computer-readable recording medium stores a paper type identification program that causes the computer to execute the paper type identification method according to any one of claims 14 to 26.

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