Discrimination device and image forming apparatus

Abstract

A discrimination device includes: a processor configured to discriminate a first sheet on which coating processing for suppressing gloss of a sheet surface is performed and a second sheet on which coating processing for suppressing gloss of a sheet surface is not performed; a light source that irradiates light to the surface of the paper; a first photodetector that detects the light reflected by the surface of the sheet; and a second photodetector that is provided at a position different from that of the first photodetector and detects diffuse reflection light of the light reflected by the surface of the sheet, the first photodetector being located in a direction deviating from a specular reflection direction of the light reflected by the surface of the sheet by a predetermined angle, and the second photodetector being located in a direction deviating from a specular reflection direction of the light reflected by the surface of the sheet by a predetermined angle. The processor acquires a light quantity ratio, which is a ratio between a light quantity detected by the first photodetector and a light quantity detected by the second photodetector; and determining whether the sheet is the first sheet or the second sheet on the basis of the relationship between the light quantity ratio and a predetermined threshold value.

Description

Technical Field

[0001] The present invention relates to a discriminating device and an image forming device. Background Art

[0002] A media sensor device is known that automatically identifies the type of paper by reading the paper used for printing with a sensor. An image forming device is controlled according to the type of paper identified by the media sensor device. For example, the image forming device controls operations related to paper conveyance, a transfer device, or a fixing device, etc., according to the type of paper. Thus, printing suitable for the type of paper is achieved, and a desired printed matter is obtained.

[0003] Patent Document 1 discloses a recording medium smoothness detection device that detects the smoothness of the surface of a recording medium. This document describes setting printing conditions of an image forming device based on the detected smoothness.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2015-215338

[0005] It is desirable to be able to distinguish between paper that has been subjected to a coating process for suppressing the gloss of the paper surface and paper that has not been subjected to such a process. Summary of the invention

[0006] An object of the present invention is to provide a discriminating device for discriminating between paper that has been subjected to a coating process for suppressing the gloss of the paper surface and paper that has not been subjected to such a process, or an image forming apparatus including the discriminating device.

[0007] The invention involved in scheme 1 is a discrimination device, which comprises: a processor for discriminating between a first paper that has been subjected to a coating process for suppressing the gloss of the paper surface and a second paper that has not been subjected to a coating process for suppressing the gloss of the paper surface; a light source for irradiating light onto the paper surface; a first photodetector for detecting the light reflected by the paper surface; and a second photodetector for detecting diffusely reflected light of the light reflected by the paper surface, the first photodetector being located in a direction deviating by a certain angle from the mirror reflection direction of the light reflected by the paper surface, the processor performing the following processing: obtaining a ratio of the light amount detected by the first photodetector to the light amount detected by the second photodetector, i.e., a light amount ratio; and discriminating whether the paper is the first paper or the second paper based on the relationship between the light amount ratio and a predetermined threshold value.

[0008] The invention according to claim 2 is the discrimination device according to claim 1, wherein the second photodetector is located in a normal direction relative to the surface of the paper.

[0009] The invention according to claim 3 is the discrimination device according to claim 1 or 2, wherein the first photodetector is located in a direction deviated by approximately 20 degrees from a specular reflection direction of the light reflected by the paper surface.

[0010] The invention according to claim 4 is an image forming apparatus including the determination device according to any one of claims 1 to 3.

[0011] The invention involved in scheme 5 is a discrimination device, which comprises: a processor for discriminating between a first paper that has been subjected to a coating process for suppressing the gloss of the paper surface and a second paper that has not been subjected to a coating process for suppressing the gloss of the paper surface; a light source for irradiating light onto the paper surface; a first photodetector for detecting the light reflected by the paper surface; and a second photodetector for detecting diffusely reflected light of the light reflected by the paper surface, the first photodetector being located in a direction deviating by a certain angle from the mirror reflection direction of the light reflected by the paper surface, the processor performing the following processing: obtaining a light quantity difference which is a difference between the light quantity detected by the first photodetector and the light quantity detected by the second photodetector; and discriminating whether the paper is the first paper or the second paper based on the relationship between the light quantity difference and a predetermined threshold value.

[0012] The invention according to claim 6 is the discrimination device according to claim 5, wherein the second photodetector is located in a normal direction relative to the surface of the paper.

[0013] The invention according to claim 7 is the discrimination device according to claim 5 or 6, wherein the first photodetector is located in a direction deviated by approximately 20 degrees from the specular reflection direction of the light reflected by the paper surface.

[0014] The invention according to claim 8 is an image forming apparatus including the discrimination device according to any one of claims 5 to 7.

[0015] Effects of the Invention

[0016] According to the first or fifth aspect of the present invention, it is possible to distinguish between paper that has been subjected to a coating process for suppressing the gloss of the paper surface and paper that has not been subjected to such a process.

[0017] According to the second or sixth aspect of the present invention, even when the incident angle (angle other than 0 degree) of the light from the light source changes, the diffuse reflected light can be detected by the second photodetector.

[0018] According to the third or seventh aspect of the present invention, the discrimination accuracy between the first paper and the second paper can be improved compared to a case where the first photodetector is not located in a direction deviated by approximately 20 degrees from the specular reflection direction of light.

[0019] According to the fourth or eighth aspect of the present invention, the discrimination result between the first paper and the second paper can be used in the main body of the image forming apparatus. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0021] Figure 1 is a diagram showing a structure of an image forming apparatus according to an embodiment;

[0022] Figure 2 is a functional block diagram of an image forming apparatus according to an embodiment;

[0023] Figure 3 is a diagram showing a structure of a sensor device according to an embodiment;

[0024] Figure 4 This indicates the incident angle of light at 70 degrees. Figure 4 (a) plain paper and Figure 4 (b) a graph showing the value of the light intensity corresponding to the light receiving angle of the matte coated paper divided by the light intensity at the light receiving angle of 0 degrees (light intensity ratio);

[0025] Figure 5 is a flow chart showing the discrimination process of matte coated paper and plain paper;

[0026] Figure 6 is a flow chart showing another discrimination process between matte coated paper and plain paper;

[0027] Figure 7 This is a diagram illustrating the hardware configuration of a computer.

[0028] Explanation of symbols

[0029] 10-image forming device, 12-main body, 14-discriminating device, 16-sensor device, 20-insertion port, 24-control device, 30-light source, 31-first photodetector, 32-second photodetector, 33-third photodetector, 50-control device, 52-transmitting device, 54-transferring device, 56-fixing device, 40-cable, 1002-processor, 1004-memory, 1006-auxiliary storage device, 1008-input and output device, 1010-network interface, 1012-bus, P-paper. DETAILED DESCRIPTION

[0030] <Overview>

[0031] Hereinafter, the embodiments of the present invention will be described in detail while confirming the accompanying drawings. The structures described below are examples for explanation and can be appropriately changed. Furthermore, in the case where the following includes multiple embodiments or variations, it is conceivable from the beginning that the characteristic parts thereof are appropriately combined and used. In all the drawings, the same or similar elements are marked with the same symbols, and repeated descriptions are omitted.

[0032] Hereinafter, a discriminating device for discriminating between a first paper subjected to a coating process for suppressing the gloss of the paper surface and a second paper not subjected to the coating process or an image forming apparatus including the discriminating device will be described.

[0033] The first paper coated to suppress the gloss of the paper surface may be matte coated paper or equivalent paper, for example. The second paper not coated to suppress the gloss of the paper surface may be plain paper or equivalent paper, for example.

[0034] As an example, the light source may be an LED (Light Emitting Diode), an LD (Laser Diode), a Vertical Cavity Surface Emitting Laser (VCSEL), or the like.

[0035] The photodetector may be, for example, a photodiode.

[0036] As an example, the identification device may be composed of only a sensor device separated from the main body of the image forming device, or may be composed of a combination of the sensor device and the main body of the image forming device. Furthermore, the identification device may be provided on a paper conveying path of the image forming device.

[0037] The discrimination device may perform another paper type discrimination process at least one of before and after performing the paper type discrimination process described below.

[0038] As an example, the image forming apparatus may be an apparatus that prints on a recording medium using a printing method such as electrophotography, inkjet, offset printing, gravure printing, etc. The image forming apparatus may apply image forming conditions corresponding to the paper discriminated by the discriminating device to the apparatus and part related to image formation and perform printing processing on the paper.

[0039] <Implementation Method>

[0040] Hereinafter, an embodiment of distinguishing between matte coated paper, which is paper subjected to a coating process for suppressing the gloss of the paper surface, and plain paper, which is paper not subjected to such a process, will be described.

[0041] Figure 1 FIG. 1 is a diagram showing a configuration of an image forming apparatus 10 according to an embodiment. Figure 2 2 is a functional block diagram of the image forming apparatus 10 . The image forming apparatus 10 includes a main body 12 and a sensor device 16 .

[0042] The main body 12 of the image forming apparatus 10 is a device that forms an image based on image information obtained from a computer (not shown) such as a PC connected thereto. In this embodiment, the main body 12 of the image forming apparatus 10 is an electrophotographic printing device. The main body 12 of the image forming apparatus 10 includes a control device 50, a conveying device 52, a transfer device 54, a fixing device 56, and the like.

[0043] like Figure 1 As shown, the sensor device 16 includes an insertion port 20 for inserting a paper P. The sensor device 16 is a device for detecting the properties of the paper P inserted into the insertion port 20. The sensor device 16 is connected to the main body 12 of the image forming apparatus 10 via a cable 40. The cable 40 supplies power from the main body 12 to the sensor device 16, and transmits information about the paper detected by the sensor device 16 to a control device 50 of the main body 12.

[0044] like Figure 2 As shown, the sensor device 16 includes a control device 24, a light source 30, and a first photodetector 31, a second photodetector 32, and a third photodetector 33. The control device 24 may include, for example, a microcontroller. The light source 30 is an LED. The first photodetector 31, the second photodetector 32, and the third photodetector 33 are photodiodes.

[0045] The control device 24 controls the light source 30 via the cable 40 according to the instruction from the control device 50 of the main body 12 or a computer (not shown) such as a PC connected to the main body 12. Then, the control device 24 irradiates light from the light source 30 to the paper P and obtains the detection values ​​of the first photodetector 31, the second photodetector 32, and the third photodetector 33. Then, the control device 24 sends the obtained detection values ​​to the control device 50 of the main body 12. The control device 50 of the main body 12 determines the type of the paper P based on the detection values ​​from the control device 24 and the threshold value pre-stored in the storage device in the control device 50. In this way, the sensor device 16 and the control device 50 of the main body 12 function as the paper type determination device 14.

[0046] An example of the operation of forming an image by the image forming apparatus 10 will be described. First, image information input from a computer such as a PC connected to the main body 12 is stored in a storage device in the control device 50. After the user sets paper P in the insertion port 20 of the sensor device 16 and determines the type of paper P, the user sets paper P in the paper feed cassette of the main body 12.

[0047] As described above, the control device 50 of the main body 12 determines the type of paper P based on the information sent from the sensor device 16. The control device 50 stores image forming conditions for each type of paper P. The image forming conditions are, for example, conditions related to the control of the conveying device 52, the transfer device 54, the fixing device 56, etc. The control device 50 supplies the paper P in the paper supply box and performs printing processing according to the image information. At this time, the control device 50 applies the image forming conditions associated with the identified paper P to at least one of the conveying device 52, the transfer device 54 and the fixing device 56 to perform printing processing on the paper P. For example, in the transfer device 54, the secondary transfer voltage as an example of the image forming condition is controlled according to the type of the identified paper.

[0048] Next, the discrimination between matte coated paper and plain paper will be described in detail. The discrimination device 14 has a function of discriminating between matte coated paper and plain paper. Figure 3 1 is a diagram schematically showing the structure of the sensor device 16. As described above, the sensor device 16 includes the light source 30, the first photodetector 31, the second photodetector 32, and the third photodetector 33.

[0049] The light source 30 irradiates light at an incident angle θ1. In this embodiment, θ1 is 70 degrees. θ1 can be changed as appropriate.

[0050] The first photodetector 31 is located in a direction deviated by a certain angle θ2 from the specular reflection direction of the light from the light source 30 reflected by the surface of the paper P. The third photodetector 33 is located in the specular reflection direction of the light from the light source 30. In this embodiment, θ2 is 20 degrees.

[0051] The second photodetector 32 is located in the normal direction to the surface of the paper P. The second photodetector 32 detects diffuse reflected light reflected from the surface of the paper P. The light source 30 and the first and second photodetectors 31 and 32 are used to distinguish between matte coated paper and plain paper.

[0052] Here, the principle of the method of distinguishing matte coated paper from plain paper is described. Figure 4 This indicates the incident angle of light at 70 degrees. Figure 4 (a) plain paper and Figure 4(b) is a graph showing the value of the light intensity received at a light receiving angle of 0 degrees for matte coated paper divided by the light intensity received at a light receiving angle of 0 degrees (light intensity ratio).

[0053] Figure 4 (a) Figure 4 The horizontal axis of the graph (b) is the light receiving angle, and the vertical axis is the light quantity ratio. In addition, regarding the light receiving angle, the normal direction relative to the surface of the paper P is set to 0 degrees, and the tilt angle toward the light source 30 side is represented by a negative value, and the tilt angle toward the mirror reflection direction side is represented by a positive value. Figure 4 In the figure, the receiving angle of 70 degrees is the direction of specular reflection. Figure 4 (a) Figure 4 The multiple lines in (b) represent the results of one type of paper. That is, Figure 4 The multiple lines in (a) represent the results of various types of plain paper. Figure 4 The multiple lines in (b) represent the results for various types of matte coated papers.

[0054] from Figure 4 It can be seen that the difference in the amount of light received between ordinary paper and matte coated paper is obvious near a light receiving angle of 50 degrees, which is about 20 degrees away from the mirror reflection direction (light receiving angle of 70 degrees). Near a light receiving angle of 50 degrees, a relatively high amount of light is received in ordinary paper, while a relatively low amount of light received in matte coated paper, which is close to the amount of light received at a light receiving angle of 0 degrees, is obtained. Therefore, by obtaining the amount of light at a position that deviates about 20 degrees from the mirror reflection direction, matte coated paper and ordinary paper can be distinguished based on the amount of light. In this embodiment, these papers are distinguished based on this principle.

[0055] As reference Figure 3 As described above, the light source 30 irradiates light at an incident angle of 70 degrees. The first photodetector 31 is located in a direction that is 20 degrees away from the specular reflection direction (receiving angle 70 degrees) of the light from the light source 30, that is, in a direction of receiving angle 50 degrees. The second photodetector 32 is located in a direction of receiving angle 0 degrees.

[0056] In addition, the first photodetector 31 can be located in a direction that deviates from the mirror reflection direction of light by an angle of 20 degrees or close to 20 degrees (approximately 20 degrees), for example. Thus, it is possible to expect relatively high-precision discrimination between matte coated paper and ordinary paper. However, the position of the first photodetector 31 is not limited to this direction. When the paper P is ordinary paper, the first photodetector 31 can be set at a position that receives a higher amount of reflected light than when the paper P is matte coated paper. And, as Figure 3 As shown, the first photodetector 31 may be located on the normal direction side relative to the mirror reflection direction of light (the direction where the third photodetector 33 is located), or may be located on the paper P side relative to the mirror reflection direction of light.

[0057] As described above, the second photodetector 32 is located in the normal direction to the surface of the paper P. However, the position of the second photodetector 32 is not limited to this direction. The second photodetector 32 may be located at a position where the amount of diffusely reflected light from the paper P can be detected.

[0058] Figure 5 1 is a flowchart showing the discrimination process of matte coated paper and plain paper. In step S100, the control device 24 of the sensor device 16 irradiates light from the light source 30 to the paper P. In step S102, the control device 24 obtains the detection value of the first photodetector 31 as the first light quantity. In step S104, the control device 24 obtains the detection value of the second photodetector 32 as the second light quantity. Then, the control device 24 sends the first light quantity and the second light quantity to the main body 12 of the image forming device 10. The control device 50 of the main body 12 receives the first light quantity and the second light quantity.

[0059] In step S106, the control device 50 of the main body 12 divides the first light amount by the second light amount to calculate the light amount ratio (= first light amount / second light amount). Next, in step S108, the control device 50 checks whether the light amount ratio is greater than a predetermined threshold value Rth stored in its own storage device.

[0060] If the answer is “Yes” in step S108 , the control device 50 determines that the paper P is plain paper in step S110 . On the other hand, if the answer is “No” in step S108 , the control device 50 determines that the paper P is matte coated paper in step S112 .

[0061] According to the above-described embodiment, it is possible to distinguish between matte coated paper and plain paper.

[0062] In addition, Figure 5 In step S106, the light quantity ratio is obtained by using the second light quantity as the denominator and the first light quantity as the numerator. However, the light quantity ratio may also be obtained by using the first light quantity as the denominator and the second light quantity as the numerator (light quantity ratio = second light quantity / first light quantity). In this case, in step S108, the control device 50 determines that the paper P is ordinary paper when the light quantity ratio is below the threshold value, and determines that the paper P is matte coated paper when it is not the case.

[0063] <Another embodiment>

[0064] Next, another discrimination process between matte coated paper and plain paper will be described. Figure 6 This is a flowchart showing another discrimination process of matte coated paper and plain paper. Figure 6 Steps S200 to S204 are Figure 5The same processing is performed as in steps S100 to S104. Figure 6 Step S206 and later Figure 5 The flow chart is different.

[0065] In step S206, the control device 50 of the main body 12 calculates the light quantity difference (= first light quantity - second light quantity) by subtracting the second light quantity from the first light quantity. Next, in step S208, the control device 50 checks whether the light quantity difference is greater than a predetermined threshold value Dth stored in its own storage device.

[0066] If the answer is “Yes” in step S208 , the control device 50 determines that the paper P is plain paper in step S210 . On the other hand, if the answer is “No” in step S208 , the control device 50 determines that the paper P is matte coated paper in step S212 .

[0067] In another embodiment described above, it is also possible to distinguish between matte coated paper and plain paper.

[0068] In addition, Figure 6 In step S206, the light quantity difference is obtained by subtracting the second light quantity from the first light quantity. However, the light quantity difference may also be obtained by subtracting the first light quantity from the second light quantity (light quantity difference = second light quantity - first light quantity). In this case, in step S208, the control device 50 determines that the paper P is ordinary paper when the light quantity difference is below the threshold value, and determines that the paper P is matte coated paper when it is not.

[0069] In the above-described embodiment, matte coated paper and ordinary paper are distinguished based on the first light amount and the second light amount. However, it is also possible to distinguish them without using the second light amount. In this case, for example, the control device 50 can distinguish the paper P as ordinary paper when the first light amount is greater than a predetermined threshold value, and distinguish the paper P as matte coated paper when it is not.

[0070] <Control device structure>

[0071] The control device of the above-mentioned embodiment can be constructed using a computer. The control device can be constructed as a system composed of, for example, a single computer or a plurality of computers cooperating with each other. Figure 7In the example shown in the figure, the computer serving as the basis of the control device has, for example, a control processor 1002, a memory (main storage device) 1004 such as a random access memory (RAM), a controller of a non-volatile storage device such as a flash memory or an SSD (solid state drive) or an HDD (hard disk drive), which is an auxiliary storage device 1006, an interface with various input and output devices 1008, a network interface 1010 for controlling connection with a network, and other circuit structures connected via a data transmission path such as a bus 1012. A program describing the processing content is installed in the computer via a network or the like, and is stored in the auxiliary storage device 1006. The control device of this embodiment is configured by executing the program stored in the auxiliary storage device 1006 using the memory 1004 by the processor 1002.

[0072] Furthermore, the above-mentioned program can of course be provided via a network such as the Internet, and can also be provided by being stored in a computer-readable recording medium such as an optical disk or a USB memory.

[0073] In the above-mentioned embodiment, the processor refers to a processor in a broad sense, including a general-purpose processor (for example, CPU: Central Processing Unit, etc.) or a dedicated processor (for example, GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.).

[0074] Furthermore, the actions of the processors in the above embodiments may be performed not only by one processor but also by a plurality of processors in physically separate locations working together. Furthermore, the actions of the processors are not limited to the order described in the above embodiments and may be changed as appropriate.

[0075] (Note) (1)

[0077] A discrimination device, comprising:

[0078] A processor for distinguishing between a first paper sheet that has been subjected to a coating process for suppressing the gloss of the paper surface and a second paper sheet that has not been subjected to a coating process for suppressing the gloss of the paper surface;

[0079] A light source, irradiating light onto the surface of the paper;

[0080] a first photodetector for detecting the light reflected by the surface of the paper; and

[0081] The second photodetector is disposed at a position different from the first photodetector and detects diffusely reflected light of the light reflected by the surface of the paper.

[0082] The first photodetector is located in a direction deviated by a certain angle relative to the specular reflection direction of the light reflected by the paper surface.

[0083] The processor performs the following processing:

[0084] acquiring a light quantity ratio which is a ratio of the light quantity detected by the first photodetector to the light quantity detected by the second photodetector; and

[0085] Whether the paper is the first paper or the second paper is determined based on the relationship between the light amount ratio and a predetermined threshold value. (2)

[0087] The determination device according to (1), wherein:

[0088] The second photoelectric detector is located in a normal direction relative to the paper surface. (3)

[0090] The determination device according to (1) or (2), wherein:

[0091] The first photodetector is located in a direction deviated by approximately 20 degrees from the specular reflection direction of the light reflected by the paper surface. (4)

[0093] An image forming apparatus includes the determination device described in any one of (1) to (3). (5)

[0095] A discrimination device, comprising:

[0096] A processor for distinguishing between a first paper sheet that has been subjected to a coating process for suppressing the gloss of the paper surface and a second paper sheet that has not been subjected to a coating process for suppressing the gloss of the paper surface;

[0097] A light source, irradiating light onto the surface of the paper;

[0098] a first photodetector for detecting the light reflected by the surface of the paper; and

[0099] The second photodetector is disposed at a position different from the first photodetector and detects diffusely reflected light of the light reflected by the surface of the paper.

[0100] The first photodetector is located in a direction deviated by a certain angle relative to the specular reflection direction of the light reflected by the paper surface.

[0101] The processor performs the following processing:

[0102] acquiring a light quantity difference which is a difference between the light quantity detected by the first photodetector and the light quantity detected by the second photodetector; and

[0103] Whether the paper is the first paper or the second paper is determined based on the relationship between the light amount difference and a predetermined threshold value. (6)

[0105] The determination device according to (5), wherein:

[0106] The second photoelectric detector is located in a normal direction relative to the paper surface. (7)

[0108] The determination device according to (5) or (6), wherein:

[0109] The first photodetector is located in a direction deviated by approximately 20 degrees from the specular reflection direction of the light reflected by the paper surface. (8)

[0111] An image forming apparatus comprises the determination device described in any one of (5) to (7).

[0112] According to the invention as set forth in (1) or (5), it is possible to distinguish between paper that has been subjected to a coating process for suppressing the gloss of the paper surface and paper that has not been subjected to such a process.

[0113] According to the invention as set forth in (2) or (6), even when the incident angle (angle other than 0 degree) of the light from the light source changes, the diffusely reflected light can be detected by the second photodetector.

[0114] According to the invention of (3) or (7), the accuracy of distinguishing the first paper and the second paper can be improved compared to a case where the first photodetector is not located in a direction deviated by approximately 20 degrees from the specular reflection direction of light.

[0115] According to the invention as set forth in (4) or (8), the discrimination result between the first paper and the second paper can be used in the main body of the image forming apparatus.

[0116] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. A determination device, comprising: A processor for distinguishing between a first paper sheet that has been subjected to a coating process for suppressing the gloss of the paper surface and a second paper sheet that has not been subjected to a coating process for suppressing the gloss of the paper surface; A light source, irradiating light onto the surface of the paper; a first photodetector for detecting the light reflected by the surface of the paper; and The second photodetector is disposed at a position different from the first photodetector and detects diffusely reflected light of the light reflected by the surface of the paper. The first photodetector is located in a direction deviated by a certain angle relative to the specular reflection direction of the light reflected by the paper surface. The processor performs the following processing: acquiring a light quantity ratio which is a ratio of the light quantity detected by the first photodetector to the light quantity detected by the second photodetector; and Whether the paper is the first paper or the second paper is determined based on the relationship between the light amount ratio and a predetermined threshold value.

2. The identification device according to claim 1, wherein: The second photoelectric detector is located in a normal direction relative to the paper surface.

3. The identification device according to claim 1 or 2, wherein: The first photodetector is located in a direction deviated by approximately 20 degrees from the specular reflection direction of the light reflected by the paper surface. 4 . An image forming apparatus comprising the determination device according to claim 1 .

5. A determination device, comprising: A processor for distinguishing between a first paper sheet that has been subjected to a coating process for suppressing the gloss of the paper surface and a second paper sheet that has not been subjected to a coating process for suppressing the gloss of the paper surface; A light source, irradiating light onto the surface of the paper; a first photodetector for detecting the light reflected by the surface of the paper; and The second photodetector is disposed at a position different from the first photodetector and detects diffusely reflected light of the light reflected by the surface of the paper. The first photodetector is located in a direction deviated by a certain angle relative to the specular reflection direction of the light reflected by the paper surface. The processor performs the following processing: acquiring a light quantity difference which is a difference between the light quantity detected by the first photodetector and the light quantity detected by the second photodetector; and Whether the paper is the first paper or the second paper is determined based on the relationship between the light amount difference and a predetermined threshold value.

6. The identification device according to claim 5, wherein: The second photoelectric detector is located in a normal direction relative to the paper surface.

7. The identification device according to claim 5 or 6, wherein: The first photodetector is located in a direction deviated by approximately 20 degrees from the specular reflection direction of the light reflected by the paper surface. 8 . An image forming apparatus comprising the determination device according to claim 5 .

Images