JP2017215331A - Sensor device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sensor which can specify an object accurately with a simple configuration.SOLUTION: A light source 10 emits S-polarized light. An optical receiver 13 mainly receives surface positive reflection light. An optical receiver 14 receives a P-polarization component included in internal diffusion reflection light. An optical receiver 15 mainly receives surface diffusion reflection light. A printer control apparatus stores output level of each optical receiver, which are measured in advance for a plurality of kinds of recording sheets of known brands, when an optical sensor 2245 is in a first posture and a second posture, as brand-based output level data. The printer control apparatus irradiates a recording sheet M to be determined with light from the light source 10, determines output level of each optical receiver, refers to the brand-based output level data, and calculates matching ratio RH and matching ratio RV for each brand, to determine a brand having the maximum value of either one as a brand of the recording sheet M.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a sensor device and an image forming apparatus, and more particularly to a sensor device having an optical sensor and an image forming apparatus including the sensor device.

  An image forming apparatus such as a digital copying machine or a laser printer transfers a toner image onto the surface of a recording medium represented by printing paper and heats and presses it under predetermined conditions to fix the image and form an image. Yes. It is the heating amount and pressure conditions during fixing that must be taken into consideration in image formation. In particular, in order to perform high-quality image formation, it is necessary to individually set the fixing conditions according to the recording medium.

  This is because the image quality on the recording medium is greatly influenced by the material, thickness, humidity, smoothness, coating state, and the like. For example, with regard to smoothness, depending on the fixing conditions, the toner fixing rate for the concave portions in the unevenness on the surface of the printing paper is lowered. Therefore, color unevenness occurs unless fixing is performed under the correct conditions according to the recording medium.

  Furthermore, with recent advances in image forming devices and diversification of expression methods, there are hundreds of types of recording media, even on printing paper alone, and there are differences in specifications such as basis weight and thickness for each type. There are a wide variety of brands. In order to form a high-quality image, it is necessary to set fine fixing conditions according to each of these brands.

  In recent years, the brands of plain paper, gloss coated paper, mat coated paper, coated paper typified by art coated paper, plastic sheets, and special paper with an embossed surface are increasing.

  In current image forming apparatuses, the user himself / herself has to set fixing conditions at the time of printing. For this reason, the user is required to have knowledge for identifying the paper type, and the user has to input the setting contents corresponding to the paper type by himself / herself. If the setting contents are incorrect, an optimum image cannot be obtained.

  There is known an optical method for irradiating a recording medium with light and receiving reflected light or transmitted light to detect the brand or surface state of the recording medium.

  For example, Patent Document 1 discloses a recording material identification device that identifies the type of recording material using reflected light and transmitted light.

  Patent Document 2 discloses a sheet material material discrimination device that discriminates the material of a sheet material based on the reflected light amount reflected on the surface of the moving sheet material and the transmitted light amount transmitted through the sheet material.

  Further, Patent Document 3 discloses a reflection type optical sensor that determines the type of a recording material stored in a paper feeding unit, and a recording material stored in the paper feeding unit based on a detection output from the reflection type optical sensor. An image forming apparatus having a determination unit that determines presence / absence and presence / absence of a sheet feeding unit is disclosed.

  Further, Patent Document 4 discloses a state detection unit that detects a plurality of polarization components of reflected light that is reflected by irradiating light onto a recording medium, and a high-pressure supply unit that supplies a high-voltage output value for image formation. An image forming apparatus including an output control unit that controls a high voltage output value of a high voltage supply unit based on a detection result of a plurality of polarization components by a state detection unit is disclosed.

  Further, Patent Document 5 discloses an irradiation system that emits linearly polarized light in the first polarization direction to a sheet-like object, and a first light beam that is arranged on the optical path of light emitted from the irradiation system and regularly reflected by the object. 1 optical detector, an optical element that transmits a linearly polarized light component having a second polarization direction orthogonal to the first polarization direction of light diffusely reflected by the object, and light that has passed through the optical element is received. An optical sensor comprising a second photodetector is disclosed.

  Further, in Patent Document 6, in order to detect light emitted to the measurement object and propagated in the fiber direction of the measurement object and emitted out of the fiber, a light axis irradiated by the irradiation unit and A detection means for detecting light that is substantially parallel and leaks from a virtual circumference centered on the light axis irradiated by the irradiation means is provided, and the fiber orientation characteristic of the measurement object is measured based on the light detected by the detector. An apparatus for measuring fiber orientation characteristics is disclosed.

  Patent Document 7 discloses a light projecting unit that irradiates detection light composed of linearly polarized light perpendicular to the paper surface and rotates the vibration direction of the linearly polarized light around the incident optical axis, and the incident optical axis as the center. A paper fiber orientation measuring device is disclosed that includes a pair of light receiving means that rotate in synchronization with the rotation of the light projecting means and separate and capture the main linearly polarized light and the sub linearly polarized light from the reflected light.

  In Patent Document 8, the fiber orientation on the surface of the recording medium is detected by using a plurality of light receiving elements that receive a plurality of reflected light having the same reflection angle from the surface of the recording medium and different reflection directions. First detecting means that detects the glossiness of the surface of the recording medium using at least one of the plurality of light receiving elements, and the detected fiber orientation and glossiness. Based on the above, there is disclosed a recording medium type discriminating device comprising discriminating means for discriminating the type of recording medium.

  However, it has been difficult to accurately identify an object with a simple configuration.

  The present invention relates to an optical sensor having a light source and a plurality of photodetectors that receive light emitted from the light source and specularly reflected by an object and diffusely reflected light, and a plurality of types that are known and different from each other. With respect to the object of the kind, it was acquired in advance when the incident direction of the light from the optical sensor was the first direction with respect to the object and the second direction orthogonal to the first direction. A database including output data of the plurality of photodetectors, irradiating light from the light source to an object of unknown type, and comparing the obtained output data of the plurality of photodetectors with the database, And a processing device that determines a type of an object whose type is unknown.

  According to the optical sensor of the present invention, an object can be specified with high accuracy with a simple configuration.

1 is a diagram for describing a schematic configuration of a color printer according to an embodiment of the present invention. FIG. It is a figure for demonstrating the structure of the optical sensor in FIG. It is a figure for demonstrating a surface emitting laser array. It is a figure for demonstrating incident angle (theta) of the irradiation light to a recording paper. It is a figure for demonstrating the arrangement position of the light receiver 13 and the light receiver. It is a figure for demonstrating the arrangement position of the light receiver. FIG. 7A is a diagram for explaining surface regular reflection light, FIG. 7B is a diagram for explaining surface diffuse reflection light, and FIG. 7C is a diagram explaining internal diffuse reflection light. It is a figure for doing. It is a figure for demonstrating the reflected light which injects into a polarizing filter. It is a figure for demonstrating the light received with the light receiver. It is a figure for demonstrating the light received with the light receiver 13 and the light receiver. FIG. 11A and FIG. 11B are diagrams for explaining the sensor driving mechanism. FIG. 12A is a diagram for explaining the first posture, and FIG. 12B is a diagram for explaining the second posture. It is a figure for demonstrating brand-specific output level data. It is a figure for demonstrating P detection positions. It is a flowchart for demonstrating a 1st processing method. It is a flowchart for demonstrating the 2nd processing method. It is a flowchart (the 1) for demonstrating a 3rd processing method. It is a flowchart (the 2) for demonstrating a 3rd processing method. It is a flowchart for demonstrating the 4th processing method. It is a figure for demonstrating a 3rd attitude | position. It is a figure for demonstrating the output level data according to brand in the 4th processing method. It is a figure for demonstrating angle (beta). It is a figure for demonstrating the relationship between angle (beta) and the change rate of the light reception amount of the light receiver. It is a figure for demonstrating the modification of a surface emitting laser array. It is a figure for demonstrating the modification of an optical sensor.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 according to an embodiment.

  The color printer 2000 is a tandem multi-color printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes an optical scanning device 2010, four photosensitive drums (2030a, 2030b, 2030c, 2030d), four cleaning units (2031a, 2031b, 2031c, 2031d), four charging devices (2032a, 2032b, 2032c, 2032d), four developing rollers (2033a, 2033b, 2033c, 2033d), transfer Belt 2040, transfer roller 2042, fixing device 2050, paper feed roller 2054, paper discharge roller 2058, paper feed tray 2060, paper discharge tray 2070, communication control device 2080, optical sensor 2245, sensor drive mechanism 2248 (in FIG. 1) Shows omitted, and a like FIGS. 11 (A) and 11 (B) refer) and a printer controller 2090 for totally controlling the above elements.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 2090 includes a CPU, a program described in a code decodable by the CPU, a ROM storing various data used when executing the program, a RAM that is a working memory, an amplification circuit And an A / D conversion circuit for converting an analog signal into a digital signal. The printer control device 2090 controls each unit in response to a request from the host device, and sends image information from the host device to the optical scanning device 2010.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, and the cleaning unit 2031a are used as a set, and constitute an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image.

  The photosensitive drum 2030b, the charging device 2032b, the developing roller 2033b, and the cleaning unit 2031b are used as a set, and constitute an image forming station (hereinafter also referred to as “C station” for convenience) that forms a cyan image.

  The photosensitive drum 2030c, the charging device 2032c, the developing roller 2033c, and the cleaning unit 2031c are used as a set, and constitute an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image.

  The photosensitive drum 2030d, the charging device 2032d, the developing roller 2033d, and the cleaning unit 2031d are used as a set, and constitute an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. That is, the surface of each photoconductive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

  The optical scanning device 2010 is correspondingly charged with light modulated for each color based on multi-color image information (black image information, cyan image information, magenta image information, yellow image information) from the printer control device 2090. Each surface of the photosensitive drum is scanned. Thereby, a latent image corresponding to the image information is formed on the surface of each photosensitive drum. The latent image formed here moves in the direction of the corresponding developing roller as the photosensitive drum rotates.

  As each developing roller rotates, toner from a corresponding toner cartridge (not shown) is thinly and uniformly applied to the surface thereof. Then, when the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves only to a portion irradiated with light on the surface and adheres to the surface. In other words, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum so as to be visualized. Here, the toner-attached image (toner image) moves in the direction of the transfer belt 2040 as the photosensitive drum rotates.

  The yellow, magenta, cyan, and black toner images are sequentially transferred onto the transfer belt 2040 at a predetermined timing, and are superimposed to form a multicolor image.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060. The paper feed roller 2054 takes out the recording paper one by one from the paper feed tray 2060. The recording paper is sent out toward the gap between the transfer belt 2040 and the transfer roller 2042 at a predetermined timing. As a result, the toner image on the transfer belt 2040 is transferred to the recording paper. The recording sheet transferred here is sent to the fixing device 2050.

  In the fixing device 2050, heat and pressure are applied to the recording paper, thereby fixing the toner on the recording paper. The recording paper fixed here is sent to a paper discharge tray 2070 via a paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  The optical sensor 2245 is used to specify the brand of recording paper stored in the paper feed tray 2060.

  As shown in FIG. 2 as an example, the optical sensor 2245 includes a light source 10, a collimating lens 12, three light receivers (13, 14, 15), a polarizing filter 16, and a dark box 19 in which these are stored. doing.

  The dark box 19 is a metal box member, for example, an aluminum box member, and has a black alumite treatment on the surface in order to reduce the influence of ambient light and stray light.

  Here, in the XYZ three-dimensional orthogonal coordinate system, the direction orthogonal to the surface of the recording paper M is described as the Z-axis direction, and the plane parallel to the surface of the recording paper M is described as the XY plane. The optical sensor 2245 is assumed to be disposed on the + Z side of the recording paper M.

  The light source 10 has a plurality of light emitting units. Each light emitting unit is a vertical cavity surface emitting laser (VCSEL). That is, the light source 10 includes a surface emitting laser array (VCSEL array). Here, as shown in FIG. 3 as an example, nine light emitting units are two-dimensionally arranged.

  The light source 10 is arranged so that the recording paper M is irradiated with S-polarized linearly polarized light. Further, the incident angle θ (see FIG. 4) of the light from the light source 10 to the recording paper M is 80 °.

  The light source 10 is turned on and off by the printer control device 2090.

  Returning to FIG. 2, the collimating lens 12 is disposed on the optical path of the light emitted from the light source 10 and makes the light substantially parallel light. The light passing through the collimating lens 12 passes through an opening provided in the dark box 19 and illuminates the recording paper M. Hereinafter, the center of the illumination area on the surface of the recording paper M is abbreviated as “illumination center”. Further, the light that has passed through the collimating lens 12 is also referred to as “irradiation light”.

  By the way, when light is incident on the boundary surface of the medium, a surface including the incident light ray and the normal of the boundary surface set at the incident point is called an “incident surface”. Therefore, when the incident light is composed of a plurality of light beams, there is an incident surface for each light beam. Here, for convenience, the incident surface of the light beam incident on the illumination center is referred to as an incident surface on the recording paper. To do. That is, the plane including the illumination center and parallel to the XZ plane is the incident plane on the recording paper.

  In this specification, the expressions S-polarized light and P-polarized light are used for reflected light as well as incident light on the recording paper M. For the sake of easy understanding, this description is based on the incident light incident on the recording paper M. The expression is based on the polarization direction, and the same polarization direction as the incident light (S polarization in this case) in the incident plane is referred to as S polarization, and the polarization direction orthogonal thereto is referred to as P polarization.

  The polarizing filter 16 is disposed on the + Z side of the illumination center. The polarizing filter 16 is a polarizing filter that transmits P-polarized light and shields S-polarized light. In place of the polarizing filter 16, a polarizing beam splitter having an equivalent function may be used.

  The light receiver 14 is disposed on the + Z side of the polarizing filter 16 and receives light transmitted through the polarizing filter 16. Here, as shown in FIG. 5, the angle ψ1 formed by the line L1 connecting the illumination center and the centers of the polarizing filter 16 and the light receiver 14 and the surface of the recording paper M is 90 °.

  The light receiver 13 is arranged on the + X side of the illumination center with respect to the X-axis direction. As shown in FIG. 5, the angle ψ2 formed by the line L2 connecting the illumination center and the center of the light receiver 13 and the surface of the recording paper M is 170 °.

  The photodetector 15 is disposed on the + X side of the illumination center with respect to the X-axis direction. As shown in FIG. 6, the angle ψ3 formed by the line L3 connecting the illumination center and the center of the photodetector 15 and the surface of the recording paper M is 120 °.

  The center of the light source 10, the center of illumination, the center of the polarizing filter 16, and the center of each light receiver are present on substantially the same plane.

  By the way, the reflected light from the recording paper when the recording paper is illuminated can be divided into reflected light reflected on the surface of the recording paper and reflected light reflected on the inside of the recording paper. Further, the reflected light reflected on the surface of the recording paper can be divided into specularly reflected light and diffusely reflected light. Hereinafter, for the sake of convenience, the reflected light that is regularly reflected on the surface of the recording paper is also referred to as “surface regular reflected light”, and the reflected light that is diffusely reflected is also referred to as “surface diffuse reflected light” (FIGS. 7A and 7B). )reference).

  The surface of the recording paper is composed of a flat portion and a slope portion, and the smoothness of the recording paper surface is determined by the ratio. The light reflected by the plane portion becomes surface regular reflection light, and the light reflected by the slope portion becomes surface diffuse reflection light. The surface diffuse reflection light is reflected light that is completely scattered and reflected, and the reflection direction can be considered to be isotropic. And the light quantity of surface regular reflection light increases, so that smoothness becomes high.

  On the other hand, when the recording paper is a general printing paper, the reflected light from the inside of the recording paper is scattered only in the fibers inside the recording paper and thus becomes only the diffuse reflected light. Hereinafter, for convenience, reflected light from the inside of the recording paper is also referred to as “internal diffuse reflected light” (see FIG. 7C). Similar to the surface diffuse reflection light, the internal diffuse reflection light is also a reflection light that has been completely scattered and reflected, and the reflection direction can be considered to be isotropic.

  The polarization direction of the surface regular reflection light and the surface diffuse reflection light is the same as the polarization direction of the incident light. By the way, in order for the polarization direction to rotate on the surface of the recording paper, the incident light must be reflected by a surface inclined in the direction of the rotation with respect to the incident direction. Here, since the center of the light source, the center of illumination, and the center of each light receiver are on the same plane, the reflected light whose polarization direction is rotated on the surface of the recording paper is not reflected in the direction of any light receiver.

  On the other hand, the polarization direction of the internally diffuse reflected light is rotated with respect to the polarization direction of the incident light. This is presumably because the light that has entered the inside of the recording paper passes through the fiber, rotates while being scattered multiple times, and the polarization direction rotates.

  Therefore, reflected light in which surface diffuse reflected light and internal diffuse reflected light are mixed enters the polarizing filter 16 (see FIG. 8).

  Since the surface diffuse reflection light is the same S-polarized light as the incident light, it is shielded by the polarization filter 16. On the other hand, since the internally diffuse reflected light contains both S-polarized light and P-polarized light, the P-polarized light component is transmitted through the polarizing filter 16. That is, the P-polarized component contained in the internally diffuse reflected light is received by the light receiver 14 (see FIG. 9). Hereinafter, for convenience, the P-polarized component included in the internally diffuse reflected light is also referred to as “P-polarized internally diffuse reflected light”. Further, the S-polarized component contained in the internally diffuse reflected light is also referred to as “S-polarized internally diffuse reflected light”.

  The inventors have confirmed that the amount of P-polarized internal diffuse reflected light has a correlation with the thickness and density of the recording paper. This is because the amount of P-polarized internal diffuse reflected light depends on the path length when passing through the fibers of the recording paper.

  Reflected light, which is a mixture of surface regular reflection light, surface diffuse reflection light, and internal diffuse reflection light, enters the light receiver 13. Since the light amount of the surface diffuse reflection light and the internal diffuse reflection light is very small compared to the light amount of the surface regular reflection light, the light reception light amount of the light receiver 13 can be regarded as the light amount of the surface regular reflection light (FIG. 10). reference).

  Reflected light in which surface diffuse reflection light and internal diffuse reflection light are mixed is incident on the light receiver 15. Since the amount of internal diffuse reflected light is very small compared to the amount of surface diffuse reflected light, the amount of light received by the light receiver 15 can be regarded as the amount of surface diffuse reflected light (see FIG. 10).

  Each light receiver outputs an electrical signal (photoelectric conversion signal) corresponding to the amount of received light to the printer control device 2090.

  The sensor driving mechanism 2248 rotates the optical sensor 2245 around the Z axis and moves it along the longitudinal direction of the recording paper M. In the following, for the sake of convenience, the longitudinal direction of the recording paper M is the L direction, and the short direction is the W direction.

  As shown in FIG. 11A and FIG. 11B as an example, the sensor drive mechanism 2248 includes a base 2248a, a shaft 2248b, a guide 2248c, a first motor 2248d, a table 2248e, a table shaft 2248f, and a second motor. 2248g.

  The base 2248a is a rectangular plate-shaped member having a screw hole into which the shaft 2248b is inserted at the + W side end portion, a through hole into which the guide 2248c is inserted at the −W side end portion, and a central portion. Has a through hole into which the table shaft 2248f is inserted.

  The shaft 2248b is a round bar whose longitudinal direction is the L direction, and a thread is formed on the surface. The guide 2248c is a round bar whose longitudinal direction is the L direction. The shaft 2248b and the guide 2248c are arranged apart from each other in the W direction. The first motor 2248d is a motor for rotating the shaft 2248b.

  The table 2248e is a disk-shaped member, and the optical sensor 2245 is attached to the surface on the −Z side. The table shaft 2248f is attached to the center of the + Z side surface of the table 2248e. The second motor 2248g is a motor for rotating the table shaft 2248f.

  Both the first motor 2248d and the second motor 2248g are driven by the printer control device 2090. When the first motor 2248d is driven, the base 2248a moves along the L direction, and the optical sensor 2245 also moves along the L direction. When the second motor 2248g is driven, the table 2248e rotates around the table shaft 2248f, and at the same time, the optical sensor 2245 also rotates around the Z axis.

  Then, as shown in FIG. 12A, the rotation state of the optical sensor 2245 when the X-axis direction of the optical sensor 2245 and the L direction of the recording paper M are parallel is referred to as a “first posture”. As shown in FIG. 12B, the rotation state of the optical sensor 2245 when the Y-axis direction of the optical sensor 2245 and the L direction of the recording paper M are parallel is referred to as a “second posture”.

  In the present embodiment, the output level of each light receiver of the optical sensor 2245 is set to the first posture in advance so that the flow direction coincides with the L direction for a plurality of brands of recording paper that the color printer 2000 can handle. And in each of the second postures. This acquisition result is stored in the ROM of the printer control apparatus 2090 as “brand-specific output level data”.

  Here, the output level of the light receiver 13 in the first posture is S1H, the output level of the light receiver 14 is S2H, the output level of the light receiver 15 is S3H, and the output level of the light receiver 13 in the second posture is S1V, the output level of the light receiver 14 is S2V, and the output level of the light receiver 15 is S3V (see FIG. 13).

  The printer control device 2090 performs a paper type discrimination process for the recording paper when the color printer 2000 is turned on and when the recording paper is supplied to the paper feed tray 2060. Various processing methods are conceivable as the paper type discrimination process. Here, four processing methods (first processing method to fourth processing method) will be described below. Note that P positions (P is a natural number) having different positions in the L direction on the recording paper M are set as detection positions (see FIG. 14).

1. First Processing Method The first processing method will be described with reference to the flowchart of FIG. This flowchart corresponds to a series of processing algorithms executed by the CPU of the printer control apparatus 2090 during the first processing method.

  In the first step S401, the optical sensor 2245 is rotated to the first posture via the sensor driving mechanism 2248.

  In the next step S403, an initial value 1 is set to a variable m in which a value for specifying the detection position is stored.

  In the next step S405, the optical sensor 2245 is moved to the mth detection position via the sensor driving mechanism 2248.

  In the next step S407, the light source 10 of the optical sensor 2245 is turned on.

  In the next step S409, the output signal of each light receiver is acquired and stored in the RAM.

  In the next step S411, the light source 10 of the optical sensor 2245 is turned off.

  In the next step S413, it is determined whether or not the value of the variable m is P or more. If the value of the variable m is less than P, the determination here is denied and the process proceeds to step S415.

  In step S415, the value of the variable m is incremented by one. Then, the process returns to step S405.

  Thereafter, the processes in steps S405 to S415 are repeated until the determination in step S413 is affirmed.

  When the value of the variable m becomes P or more, the determination in step S413 is affirmed and the process proceeds to step S417.

  In this step S417, P output levels are averaged for each light receiver. The average value of the output level of the light receiver 13 is S1 ′, the average value of the output level of the light receiver 14 is S2 ′, and the average value of the output level of the light receiver 15 is S3 ′.

  In the next step S419, with reference to the brand-specific output level data stored in the ROM of the printer control device 2090, the precision ratio RH is calculated for each brand using the following equation (1). The precision RV is calculated using the equation

  In the next step S421, a brand having a maximum of the precision ratio RH or the precision ratio RV is extracted from the precision ratio RH and the precision ratio RV calculated for each brand, and the extracted brand is recorded on the recording paper M. A brand.

  In the next step S423, the specified brand of recording paper M is stored in the RAM. Then, the first processing method ends.

2. Second Processing Method The second processing method will be described with reference to the flowchart of FIG. This flowchart corresponds to a series of processing algorithms executed by the CPU of the printer control apparatus 2090 during the second processing method.

  In the second processing method, only step S401 in the first processing method is changed to step S401 '.

  In step S401 ', the optical sensor 2245 is rotated to the second posture via the sensor driving mechanism 2248. The following is the same as the first processing method.

  That is, the second processing method differs from the first processing method only in the attitude of the optical sensor 2245.

3. Third Processing Method The third processing method will be described with reference to the flowcharts of FIGS. These flowcharts correspond to a series of processing algorithms executed by the CPU of the printer control apparatus 2090 during the third processing method.

  In the first step S501, the optical sensor 2245 is rotated to the first posture via the sensor driving mechanism 2248.

  In the next step S503, an initial value 1 is set in a variable m in which a value for specifying the detection position is stored.

  In the next step S505, the optical sensor 2245 is moved to the mth detection position via the sensor driving mechanism 2248.

  In the next step S507, the light source 10 of the optical sensor 2245 is turned on.

  In the next step S509, the output signal of each light receiver is acquired and stored in the RAM.

  In the next step S511, the light source 10 of the optical sensor 2245 is turned off.

  In the next step S513, it is determined whether or not the value of the variable m is P or more. If the value of the variable m is less than P, the determination here is denied and the process proceeds to step S515.

  In step S515, the value of the variable m is incremented by one. Then, the process returns to step S505.

  Thereafter, the processes in steps S505 to S515 are repeated until the determination in step S513 is positive.

  When the value of the variable m becomes P or more, the determination in step S513 is affirmed and the process proceeds to step S521.

  In step S521, the optical sensor 2245 is rotated to the second posture via the sensor driving mechanism 2248.

  In the next step S523, an initial value 1 is set in a variable m in which a value for specifying the detection position is stored.

  In the next step S525, the optical sensor 2245 is moved to the mth detection position via the sensor driving mechanism 2248.

  In the next step S527, the light source 10 of the optical sensor 2245 is turned on.

  In the next step S529, the output signal of each light receiver is acquired and stored in the RAM.

  In the next step S531, the light source 10 of the optical sensor 2245 is turned off.

  In the next step S533, it is determined whether or not the value of the variable m is P or more. If the value of the variable m is less than P, the determination here is denied and the process proceeds to step S535.

  In step S535, the value of the variable m is incremented by one. Then, the process returns to step S525.

  Thereafter, the processes in steps S525 to S535 are repeated until the determination in step S533 is affirmed.

  When the value of the variable m becomes P or more, the determination in step S533 is affirmed and the process proceeds to step S551.

  In step S551, the P output levels for each light receiver obtained when the optical sensor 2245 is in the first posture are averaged. The average value of the output level of the light receiver 13 is S1H ′, the average value of the output level of the light receiver 14 is S2H ′, and the average value of the output level of the light receiver 15 is S3H ′.

  In the next step S553, the P output levels for each light receiver obtained when the optical sensor 2245 is in the second posture are averaged. The average value of the output level of the light receiver 13 is S1V ′, the average value of the output level of the light receiver 14 is S2V ′, and the average value of the output level of the light receiver 15 is S3V ′.

  In the next step S555, the output level data classified by brand stored in the ROM of the printer control device 2090 is referred to, and the precision RH is calculated for each brand using the following equation (3). ) Is used to calculate the relevance ratio RV, the following expression (5) is used to calculate the relevance ratio RH ′, and the following expression (6) is used to calculate the relevance ratio RV ′.

  In the next step S557, in the relevance rate RH, the relevance rate RV, the relevance rate RH ′, and the relevance rate RV ′ calculated for each issue, the issue with which RH × RV or RH ′ × RV ′ is maximized is extracted. The extracted brand is used as the brand of the recording paper M.

  In the next step S559, the specified brand of the recording paper M is stored in the RAM. Then, the third processing method ends.

4). Fourth Processing Method The fourth processing method will be described with reference to the flowchart in FIG. This flowchart corresponds to a series of processing algorithms executed by the CPU of the printer control apparatus 2090 during the fourth processing method. As shown in FIG. 20, the rotation state of the optical sensor 2245 when the angle between the X-axis direction of the optical sensor 2245 and the L direction of the recording paper M is α (0 <α <90). "Third posture". The brand-specific output level data includes the output level S1A of the light receiver 13 in the third posture, the output level S2A of the light receiver 14, and the output level S3A of the light receiver 15 (see FIG. 21). ). Here, α = 45 ° is set as an example, but the present invention is not limited to this.

  In the first step S601, the optical sensor 2245 is rotated to the third posture via the sensor driving mechanism 2248.

  In the next step S603, an initial value 1 is set in a variable m in which a value for specifying the detection position is stored.

  In the next step S605, the optical sensor 2245 is moved to the mth detection position via the sensor driving mechanism 2248.

  In the next step S607, the light source 10 of the optical sensor 2245 is turned on.

  In the next step S609, the output signal of each light receiver is acquired and stored in the RAM.

  In the next step S611, the light source 10 of the optical sensor 2245 is turned off.

  In the next step S613, it is determined whether or not the value of the variable m is P or more. If the value of the variable m is less than P, the determination here is denied and the process proceeds to step S615.

  In step S615, the value of the variable m is incremented by one. Then, the process returns to step S605.

  Thereafter, the processes in steps S605 to S615 are repeated until the determination in step S613 is positive.

  When the value of the variable m becomes P or more, the determination in step S613 is affirmed and the process proceeds to step S617.

  In this step S617, P output levels are averaged for each light receiver. The average value of the output level of the light receiver 13 is S1 ″, the average value of the output level of the light receiver 14 is S2 ″, and the average value of the output level of the light receiver 15 is S3 ″.

  In the next step S619, with reference to the brand-specific output level data stored in the ROM of the printer control device 2090, for each brand, the relevance ratio RH is calculated using the following equation (7). ) Is used to calculate the relevance ratio RV, and the following equation (9) is used to calculate RA.

  In the next step S621, a brand having a maximum value among the precision ratio RH, precision ratio RV and precision ratio RA calculated for each brand is extracted, and the extracted brand is used as a brand of the recording paper M.

  In the next step S623, the specified brand of recording paper M is stored in the RAM. Then, the fourth processing method ends.

  Upon receiving a print job request from the user, the printer control device 2090 reads the recording paper brand stored in the RAM, and obtains the development conditions and transfer conditions optimum for the recording paper brand from the development / transfer table. .

  Then, the printer control device 2090 controls the developing device and the transfer device at each station in accordance with the optimum development conditions and transfer conditions. For example, the transfer voltage and the toner amount are controlled. Thereby, a high quality image is formed on the recording paper.

  By the way, in the recording paper, orientation of fibers constituting the recording paper is generated due to the manufacturing method. This fiber orientation is also called “flow line”, and is formed so as to follow the flow direction of the recording paper in the manufacturing process. Therefore, even with the same recording paper, the reflection characteristics may differ if the incident direction of the irradiation light is different. Here, as shown in FIG. 22, an angle formed by the incident direction of the irradiation light and the L direction when orthogonally projected onto a surface orthogonal to the surface of the recording paper M is β (°).

  FIG. 23 shows the relationship between the angle β and the change rate (%) of the amount of light received by the light receiver 15 for a plurality of recording papers having different brands. In the brand A, the flow direction is parallel to the L direction, and in the brands B, C, and D, the flow direction is orthogonal to the L direction. According to FIG. 23, in the brand A, the received light amount is the maximum when the angle β is around 90 °, and in the brands B, C, and D, the received light amount is the minimum value when the angle β is around 90 °. . This is because the diffuse reflection on the recording paper surface is the smallest when the incident surface is parallel to the flow direction, and the diffuse reflection on the recording paper surface is when the incident surface is orthogonal to the flow direction. It shows that it becomes the largest.

  In this embodiment, the output level data for each brand includes the output level of each light receiver when the incident surface is parallel to the L direction and the output level of each light receiver when the incident surface is orthogonal to the L direction. Therefore, both the brand and the flow direction of the recording paper M to be discriminated can be obtained simultaneously.

  For example, in the first processing method, when the relevance ratio RH is the maximum, the flow direction is parallel to the L direction, and when the relevance ratio RV is the maximum, the flow direction is the L direction. It can be determined that they are orthogonal.

  Also in the second processing method, when the relevance ratio RH is maximum, the flow direction is parallel to the L direction, and when the relevance ratio RV is maximum, the flow direction is L direction. Can be determined to be orthogonal.

  In the third processing method, when RH × RV is maximum, the flow direction is parallel to the L direction, and when RH ′ × RV ′ is maximum, the flow direction is L. It can be determined that the direction is orthogonal to the direction.

  As is clear from the above description, in the color printer 2000 according to the present embodiment, the printer control device 2090 constitutes the processing device and the adjustment device of the present invention, and the database of the present invention is composed of the brand-specific output level data. ing.

  As described above, the optical sensor 2245 according to this embodiment includes the light source 10, the collimating lens 12, the three light receivers (13, 14, 15), the polarizing filter 16, the dark box 19, and the like.

  The light source 10 emits S-polarized light, the light receiver 13 mainly receives the regular specular reflection light, the light receiver 14 receives the P-polarized component included in the internal diffuse reflection light, and the light receiver 15 reflects the surface diffuse reflection. It arrange | positions so that light may mainly be received.

  Further, the ROM of the printer control device 2090 outputs the outputs of the respective light receivers measured in advance for a plurality of types of recording paper whose brands are known when the optical sensor 2245 is in the first posture and the second posture. The level is stored as output level data for each brand.

  Then, the printer control device 2090 performs a paper type discrimination process of the recording paper when the color printer 2000 is turned on or when the recording paper is supplied to the paper feed tray 2060. In this paper type discrimination process, the printer control device 2090 irradiates the recording paper M to be discriminated with light from the light source 10, obtains the output level of each light receiver, and then refers to the output level data by brand. The matching rate RH and the matching rate RV are calculated for each brand, and the brand having the maximum value is used as the brand of the recording paper M.

  In this case, since the paper type is determined in consideration of the flow direction, the paper type can be determined with higher accuracy than in the past. In the conventional paper type discrimination process, the flow direction is not considered at all.

  In this embodiment, since a surface emitting laser array is used as a light source, a polarizing filter for obtaining linearly polarized irradiation light is not necessary. Furthermore, in the surface emitting laser array, it is possible to integrate a plurality of light emitting portions at a high density, which has been difficult with a conventionally used LED or the like. In this case, a small light source having a plurality of light emitting units can be realized. Further, since all the laser light can be concentrated in the vicinity of the optical axis of the collimating lens, it is possible to make a plurality of lights substantially parallel with a constant incident angle. In this case, an inexpensive collimating optical system can be used. Therefore, it is possible to reduce the size and cost of the optical sensor.

  In addition, the printer control device 2090 turns on a plurality of light emitting units of the surface emitting laser array at the same time. For this reason, the light quantity of the P-polarized component of the internal diffuse reflected light can be increased.

  Therefore, the optical sensor 2245 can separate the reflected light from the inside of the recording paper with high accuracy, which was conventionally weak and difficult to separate. The reflected light from the inside of the recording paper includes information regarding the internal state of the recording paper.

  Then, the printer control device 2090 identifies the brand of the recording paper from the output signals of the three light receivers. That is, by taking into account information relating to the internal state of the recording paper, the paper type discrimination level is improved to a brand level that has been difficult in the past.

  Moreover, since it is a simple component structure without combining a plurality of types of sensors, a small optical sensor can be realized at low cost.

  Therefore, according to the optical sensor 2245, the object can be specified with high accuracy with a simple configuration.

  Since the color printer 2000 according to this embodiment includes the optical sensor 2245, as a result, a high-quality image can be formed without increasing the cost and size. Furthermore, the troublesome printing that has to be manually set and the printing failure due to setting mistakes are eliminated.

  In the above embodiment, four processing methods (first processing method to fourth processing method) have been described as the paper type determination processing, but the present invention is not limited to these.

  Moreover, although the said embodiment demonstrated the case where there exist multiple detection positions, it is not limited to this.

  In the above embodiment, S1A, S2A, and S3A in the fourth processing method may be actually measured values. However, the relationship between the output level of each light receiver and the angle β is approximated by, for example, a sinusoidal curve. However, it may be a calculated value using the approximate curve.

  In the above-described embodiment, the case where the optimum development condition and transfer condition are set based on the brand of the recording paper has been described. However, the present invention is not limited to this. The optimum development condition and transfer condition may be set based on at least one of the brand of the recording paper and the flow direction.

  In the above embodiment, at least a part of the processing according to the program by the CPU of the printer control device 2090 may be configured by hardware, or all may be configured by hardware.

  In the above-described embodiment, the case where the sensor driving mechanism 2248 includes the base 2248a, the shaft 2248b, the guide 2248c, the first motor 2248d, the table 2248e, the table shaft 2248f, the second motor 2248g, and the like has been described. It is not limited to.

  In the above embodiment, the case where the light irradiated to the recording paper is S-polarized light has been described. However, the present invention is not limited to this, and the light irradiated to the recording paper may be P-polarized light. However, in this case, a polarizing filter that transmits S-polarized light is used instead of the polarizing filter 16, and the light receiver 14 receives the S-polarized component contained in the internally diffuse reflected light.

  Moreover, in the said embodiment, as for the some light emission part of a surface emitting laser array, at least one part light emission part space | interval may differ from other light emission part space | intervals (refer FIG. 24). That is, the interval between adjacent light emitting units may be different.

  Moreover, although the said embodiment demonstrated the case where the light source 10 had nine light emission parts, it is not limited to this.

  Moreover, although the said embodiment demonstrated the case where linearly polarized light was inject | emitted from the light source 10, it is not limited to this. However, in this case, as shown in FIG. 25 as an example, a polarizing filter 26 for making the irradiation light S-polarized light is necessary.

  Moreover, in the said embodiment, it is more preferable that the condensing lens is arrange | positioned ahead of each light receiver. In this case, fluctuations in the amount of received light at each light receiver can be reduced.

  In the above-described embodiment, a processing device may be provided in the optical sensor 2245, and a part of the processing in the printer control device 2090 may be performed by the processing device.

  In the above embodiment, the case where there is one paper feed tray has been described. However, the present invention is not limited to this, and a plurality of paper feed trays may be provided. In this case, an optical sensor 2245 may be provided for each paper feed tray.

  In the above embodiment, the brand of the recording paper may be specified during conveyance. In this case, the optical sensor 2245 is disposed in the vicinity of the conveyance path. For example, the optical sensor 2245 may be disposed in the vicinity of the conveyance path between the paper feed roller 2054 and the transfer roller 2042.

  The object identified by the optical sensor 2245 is not limited to recording paper.

  In the above embodiment, the case of the color printer 2000 as the image forming apparatus has been described. However, the present invention is not limited to this. For example, a laser printer that forms a monochrome image may be used. Further, it may be an image forming apparatus other than a printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated.

  In the above embodiment, the case where the image forming apparatus has four photosensitive drums has been described. However, the present invention is not limited to this. For example, a printer having five photosensitive drums may be used.

  In the above embodiment, the image forming apparatus is described in which the toner image is transferred from the photosensitive drum to the recording paper via the transfer belt. However, the present invention is not limited to this, and the toner image is recorded from the photosensitive drum. It may be an image forming apparatus that is directly transferred to paper.

  The optical sensor 2245 can also be applied to an image forming apparatus that forms an image by spraying ink on recording paper.

  DESCRIPTION OF SYMBOLS 10 ... Light source, 12 ... Collimating lens, 13 ... Light receiver (1st photodetector), 14 ... Light receiver (2nd photodetector), 15 ... Light receiver (3rd photodetector), 16 ... Polarizing filter (optical element), 19 ... dark box, 26 ... polarizing filter, 2000 ... color printer (image forming apparatus), 2010 ... optical scanning device, 2030a, 2030b, 2030c, 2030d ... photoconductor drum (image carrier), 2032a , 2032b, 2032c, 2032d ... charging device, 2033a, 2033b, 2033c, 2033d ... developing roller, 2040 ... transfer belt, 2042 ... transfer roller, 2050 ... fixing device, 2090 ... printer control device (processing device, adjustment device), 2245 ... optical sensor, 2248 ... sensor drive mechanism.

JP 2005-156380 A JP-A-10-160687 JP 2006-062842 A JP 11-249353 A JP 2012-127937 A Japanese Patent No. 3577713 Japanese Patent No. 2801144 Japanese Patent No. 3734247

Claims (13)

An optical sensor having a light source and a plurality of photodetectors that receive light emitted from the light source and regularly reflected by the object and light diffusely reflected;
With respect to a plurality of types of objects that are known and different from each other, when the incident direction of light from the optical sensor is the first direction with respect to the object in advance, the first direction orthogonal to the first direction A database including output data of the plurality of photodetectors acquired in the direction of 2;
A processing device that irradiates an object of unknown type with light from the light source, collates the obtained output data of the plurality of photodetectors with the database, and determines the type of the object of unknown type A sensor device comprising:   The sensor device according to claim 1, wherein the light source irradiates an object of unknown type from either the first direction or the second direction.   The sensor device according to claim 1, wherein the light source individually irradiates light from both the first direction and the second direction with respect to an object whose type is unknown.   The said light source irradiates light from the 3rd direction different from both of the said 1st direction and the said 2nd direction with respect to the target object whose type is unknown. Sensor device.   For each type in the database, the processing device calculates, for each detector, a matching rate indicating a degree of coincidence with output data when the type is an unknown object, and the type based on the matching rate The sensor device according to any one of claims 1 to 4, wherein the type of an object whose number is unknown is determined.   The processing apparatus irradiates light from the light source to a plurality of positions of an object whose type is unknown, and acquires output data of the plurality of photodetectors for each irradiation position. The sensor device according to claim 5.   The sensor device according to claim 1, wherein the light source includes a surface emitting laser array. The light source emits linearly polarized light having a first polarization direction;
The optical sensor is installed on an optical path of light diffusely reflected by the object within an incident surface of the object, and transmits a linearly polarized light component having a second polarization direction orthogonal to the first polarization direction. Having an optical element,
The plurality of photodetectors includes a first photodetector installed on an optical path of light regularly reflected by the object, and a second photodetector that receives light transmitted through the optical element. The sensor device according to claim 1, wherein the sensor device is a sensor device.   9. The plurality of photodetectors includes a third photodetector installed on an optical path of light diffusely reflected by the object within an incident surface of the object. The sensor device described.   The sensor device according to any one of claims 1 to 9, wherein the object is paper, and the first direction is a direction parallel to a flow direction.   The sensor device according to claim 10, wherein the processing device further determines a flow direction in an object whose type is unknown based on the precision. In an image forming apparatus for forming an image on a recording medium,
The sensor device according to claim 10 or 11, wherein the recording medium is an object.
An image forming apparatus comprising: an adjustment device that adjusts an image forming condition based on a determination result of the sensor device.   The image forming apparatus according to claim 12, wherein the adjusting device adjusts the image forming condition based on at least one of a brand of the recording medium and a flow direction.

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