JP6501131B2 - Type discrimination system and image forming apparatus - Google Patents

Description

The present invention relates to a type determination system and an image forming apparatus, and more particularly, to a type determination system including an optical sensor and an image forming apparatus including an optical sensor .

  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, heats and presses under predetermined conditions, fixes the image, and forms an image. There is. Conditions of heating amount and pressure at the time of fixing are to be considered in image formation, and in particular, in order to form an image of high quality, it is necessary to set fixing conditions individually according to the recording medium.

  This is because the image quality in the recording medium is greatly influenced by the material, thickness, humidity, smoothness, coating state, and the like. For example, regarding the smoothness, depending on the fixing conditions, the fixing rate of the toner on the concave portion of the unevenness of the printing paper surface is lowered. Therefore, if the fixing is not performed under the correct conditions according to the recording medium, color unevenness occurs.

  Furthermore, with the recent progress of image forming apparatuses and diversification of expression methods, there are several hundred types of recording media even with printing paper alone, and furthermore, the specifications such as basis weight and thickness differ in each type. There is 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.

  Also, in recent years, brands are increasing for coated paper represented by plain paper, gloss-coated paper, matte-coated paper, art-coated paper, plastic sheets, and special paper having an embossed surface.

  In current image forming apparatuses, the user has to set fixing conditions at the time of printing. For this reason, the user is required to have knowledge for identifying the type of paper, and there is also an inconvenience that it is necessary to input setting contents according to the type of paper each time. And if the setting contents are incorrect, it is not possible to obtain an optimal image.

  There is known an optical method of irradiating a recording medium with light, receiving its reflected light and transmitted light, and detecting the brand, surface condition, etc. 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.

  Further, Patent Document 2 discloses a sheet material discrimination apparatus for discriminating the material of a sheet material based on the amount of light reflected from the surface of the sheet material in motion and the amount of light transmitted through the sheet material.

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

  Further, Patent Document 4 discloses a state detection means for irradiating the recording medium with light and detecting a plurality of polarization components of the reflected light, and a high pressure supply means for supplying a high voltage output value for forming an image. An image forming apparatus is disclosed, comprising: output control means for controlling a high voltage output value of the high pressure supply means based on detection results of a plurality of polarization components by the state detection means.

  Further, in Patent Document 5, an irradiation system which emits linearly polarized light in a first polarization direction to a sheet-like object, and a light path which is emitted from the irradiation system and disposed on an optical path of light specularly reflected by the object An optical element for transmitting the linearly polarized light component of the second polarization direction orthogonal to the first polarization direction of the light diffusely reflected by the object; and the light transmitted through the optical element. An optical sensor is disclosed comprising a second light detector.

  Further, in Patent Document 6, the light beam axis irradiated by the irradiating means for detecting the light irradiated to the object to be measured and transmitted to the fiber direction of the object to be measured and emitted out of the fiber A detection means for detecting light leaking from a virtual circle which is substantially parallel and centered on a light axis irradiated by the irradiation means is provided, and the fiber orientation characteristic of the object to be measured is measured based on the light detected by the detector. An apparatus for measuring fiber orientation properties is disclosed.

  Further, in Patent Document 7, a light emitting means for irradiating detection light consisting of linearly polarized light perpendicular to the paper surface and rotating the vibration direction of the linearly polarized light about 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 pivots in synchronization with the rotation of the light emitting means and separates and captures main linearly polarized light and sub-linearly polarized light from reflected light.

  Further, in Patent Document 8, the fiber orientation of the surface of the recording medium is detected using a plurality of light receiving elements that receive a plurality of reflected lights having the same reflection angle from the surface of the recording medium and different reflection directions. First detecting means, and second detecting means for detecting the glossiness of the surface of the recording medium using at least one light receiving element of the plurality of light receiving elements, and the detected fiber orientation and glossiness A discriminator for the type of recording medium is disclosed, which comprises: a discriminator configured to discriminate the type of recording medium.

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

The present invention relates to an optical sensor having a light source and a plurality of light detectors for receiving light emitted from the light source and specularly reflected and diffusely reflected by an object, and a plurality of optical sensors of which types are known and different from each other Regarding the type of object, the direction of incidence of light from the optical sensor is previously acquired at a first direction with respect to the object and at a second direction orthogonal to the first direction. A database including output data of the plurality of photodetectors , and a plurality of positions of the object while moving relative to the object of unknown type from either of the first and second directions A processing device that emits light from the light source, collates the output data of the plurality of photodetectors obtained for each position with the database, and determines the type of the object whose type is unknown Type discrimination system

  According to the optical sensor of the present invention, it is possible to specify an object with high accuracy with a simple configuration.

FIG. 1 is a diagram for explaining a schematic configuration of a color printer according to an embodiment of the present invention. 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 irradiated light to a recording paper. It is a figure for demonstrating the arrangement position of the light receiver 13 and the light receiver 14. As shown in FIG. It is a figure for demonstrating the arrangement position of the light receiver 15. FIG. FIG. 7 (A) is a view for explaining surface regular reflection light, FIG. 7 (B) is a view for explaining surface diffusion reflection light, and FIG. 7 (C) is a view for explaining internal diffusion reflection light FIG. It is a figure for demonstrating the reflected light which injects into a polarization filter. It is a figure for demonstrating the light light-received by the light receiver 14. FIG. It is a figure for demonstrating the light light-received by the light receiver 13 and the light receiver 15. FIG. FIGS. 11A and 11B are diagrams for explaining the sensor drive mechanism. FIG. 12A is a view for explaining the first attitude, and FIG. 12B is a view for explaining the second attitude. 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 a 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 a 4th processing method. It is a figure for demonstrating a 3rd attitude | position. It is a figure for demonstrating the output level data classified by brand in the 4th processing method. It is a figure for demonstrating angle (beta). FIG. 7 is a diagram for explaining the relationship between the angle β and the rate of change of the amount of light received by the light receiver 15. 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 based on FIGS. 1 to 23. FIG. 1 shows a schematic configuration of a color printer 2000 according to an embodiment.

  The color printer 2000 is a tandem multicolor color printer in which four colors (black, cyan, magenta, and yellow) are superimposed to form a full-color image, and the light scanning device 2010 includes 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 A belt 2040, a transfer roller 2042, a fixing device 2050, a sheet feeding roller 2054, a sheet discharging roller 2058, a sheet feeding tray 2060, a sheet discharging tray 2070, a communication control device 2080, an optical sensor 2245, and a sensor driving 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 bi-directional communication with a higher-level 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 decipherable by the CPU, a ROM storing various data used when executing the program, a RAM as a working memory, an amplifier circuit , And an A / D conversion circuit for converting an analog signal into a digital signal. Then, the printer control device 2090 controls each unit in response to a request from the upper apparatus, and sends image information from the upper apparatus to the light scanning apparatus 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 the sake of 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 2030 d, the charging device 2032 d, the developing roller 2033 d, and the cleaning unit 2031 d 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 its surface. That is, the surface of each photosensitive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane in FIG. 1 by a rotating mechanism (not shown).

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

  The optical scanning device 2010 is charged corresponding to the light modulated for each color based on multicolor image information (black image information, cyan image information, magenta image information, yellow image information) from the printer control device 2090. The surface of the photosensitive drum is scanned respectively. Thereby, latent images corresponding to the image information are formed on the surfaces of the respective photosensitive drums. 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 the corresponding toner cartridge (not shown) is thinly and uniformly applied to the surface thereof. When the toner on the surface of each developing roller comes in contact with the surface of the corresponding photosensitive drum, it transfers only to the portion of the surface irradiated with the light and adheres there. That is, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum to make it visible. Here, the image (toner image) to which the toner is attached 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 superimposed to form a multicolor color image.

  Recording paper is stored in the paper feed tray 2060. A sheet feeding roller 2054 is disposed in the vicinity of the sheet feeding tray 2060, and the sheet feeding roller 2054 takes out recording sheets one by one from the sheet feeding tray 2060. The recording paper is fed toward the gap between the transfer belt 2040 and the transfer roller 2042 at a predetermined timing. Thus, the toner image on the transfer belt 2040 is transferred to the recording sheet. 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 sheet to fix the toner on the recording sheet. The recording sheet fixed here is sent to the sheet discharge tray 2070 through the sheet discharge roller 2058, and sequentially stacked on the sheet 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 grade of the recording sheet stored in the sheet feeding tray 2060.

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

  The dark box 19 is a metal box member, for example, a box member made of aluminum, and the surface thereof is subjected to black alumite treatment in order to reduce the influence of disturbance light and stray light.

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

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

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

  The light source 10 is turned on and off by the printer control unit 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 collimator lens 12 illuminates the recording paper M by passing through the opening provided in the dark box 19. In the following, the center of the illumination area on the surface of the recording paper M will be briefly described as the “illumination center”. Further, the light passing through the collimator 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 beam and the normal to the boundary surface set at the incident point is called an “incident surface”. Therefore, when the incident light consists of a plurality of light beams, an incident surface exists for each light beam. Here, for convenience, the incident surface of the light beam incident on the center of the illumination is referred to as the incident surface of the recording paper. 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 to the recording paper M, but for the sake of simplicity, It is an expression based on the polarization direction, and the same polarization direction as incident light (here, S polarization) in the incident plane is called S polarization, and the polarization direction orthogonal thereto is called P polarization.

  The polarization 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 blocks s-polarized light. Instead of the polarization filter 16, a polarization beam splitter having the same function may be used.

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

  The light receiver 13 is disposed on the + X side of the illumination center in the X-axis direction. Then, as shown in FIG. 5, an angle ψ2 between 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 light detector 15 is disposed on the + X side of the illumination center in the X-axis direction. Then, as shown in FIG. 6, an angle ψ3 between the line L3 connecting the illumination center and the center of the light detector 15 and the surface of the recording paper M is 120 °.

  The center of the light source 10, the center of the illumination, the center of the polarizing filter 16, and the centers of the respective light receivers lie substantially in the same plane.

  The reflected light from the recording sheet when the recording sheet is illuminated can be considered separately as the reflected light reflected on the surface of the recording sheet and the reflected light reflected on the inside of the recording sheet. Also, the reflected light reflected by the surface of the recording paper can be considered separately as the reflected light that is specularly reflected and the reflected light that is diffusely reflected. Hereinafter, for convenience, the reflected light specularly reflected on the surface of the recording paper will also be referred to as “surface regular reflected light”, and the diffusely reflected light may be referred to as “surface diffuse reflected light” (FIG. 7 (A) and FIG. )reference).

  The surface of the recording paper is composed of a flat portion and a slope portion, and the smoothness of the surface of the recording paper is determined by the ratio. The light reflected by the flat part becomes surface regular reflection light, and the light reflected by the slope part becomes surface diffuse reflection light. The surface diffuse reflection light is reflection light that is completely scattered and reflected, and the reflection direction can be considered to be isotropic. Then, as the smoothness becomes higher, the light amount of the surface regular reflection light increases.

  On the other hand, when the recording sheet is a general printing sheet, the light reflected from the inside of the recording sheet is only diffuse reflection light because it is multiple-scattered in the fibers inside the recording sheet. Hereinafter, for convenience, the 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, this internal diffuse reflection light is also a reflection light that is completely scattered and reflected, and the reflection direction can be considered to be isotropic.

  The polarization directions of the surface regular reflection light and the surface diffuse reflection light are 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, incident light must be reflected by a surface inclined to the direction of the rotation with respect to the incident direction. Here, since the centers of the light source and the illumination centers and the centers of the light receivers 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 internal diffuse reflection light is rotated with respect to the polarization direction of the incident light. This is considered to be because the light that has penetrated the inside of the recording paper is transmitted through the fiber and is rotated while being multiply scattered, and the polarization direction is rotated.

  Therefore, reflected light in which the surface diffuse reflection light and the internal diffuse reflection light are mixed is incident on the polarization filter 16 (see FIG. 8).

  The surface diffuse reflected light is s-polarized light the same as the incident light, and thus is blocked by the polarizing filter 16. On the other hand, since the internal diffuse reflection light is a mixture of S-polarization and P-polarization, the P-polarization component is transmitted through the polarization filter 16. That is, the P polarization component contained in the internal diffuse reflection light is received by the light receiver 14 (see FIG. 9). In the following, for convenience, the P-polarized light component included in the internal diffuse reflection light is also referred to as “P-polarization internal diffuse reflection light”. Further, the S-polarization component contained in the internal diffuse reflection light is also referred to as "S-polarization internal diffuse reflection light".

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

  Reflected light in which the surface regular reflection light, the surface diffuse reflection light, and the internal diffuse reflection light are mixed is incident on the light receiver 13. Since the light quantity of the surface diffuse reflection light and the internal diffuse reflection light is very small compared to the light quantity of the surface regular reflection light, the light reception quantity of the light receiver 13 can be regarded as the light quantity of the surface regular reflection light (FIG. 10) reference).

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

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

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

  As shown in FIGS. 11A and 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. It has 2248g etc.

  The base 2248a is a rectangular plate-like member, has a screw hole in which the shaft 2248b is inserted at the + W side end, and has a through hole in which the guide 2248c is inserted at the -W side end. There is a through hole into which the table shaft 2248f is inserted.

  The shaft 2248 b 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 2248 b and the guide 2248 c are disposed apart in the W direction. The first motor 2248 d is a motor for rotating the shaft 2248 b.

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

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

  Then, as shown in FIG. 12A, the rotational 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 called “first posture”. As shown in FIG. 12B, the rotational 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 become parallel is referred to as a “second attitude”.

  In the present embodiment, the output level of each light receiver of the optical sensor 2245 is set to the first attitude such that the flow direction coincides with the L direction in advance for recording papers of a plurality of brands compatible with the color printer 2000. And in the second posture. The acquisition result is stored in the ROM of the printer control device 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 of recording paper when the color printer 2000 is powered on, when the recording paper is supplied to the paper feeding tray 2060, and the like. Various processing methods can be considered as the paper type discrimination process. Here, four processing methods (first to fourth processing methods) will be described below. Note that P (P is a natural number) positions different in position 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 device 2090 in the first processing method.

  In the first step S401, the optical sensor 2245 is pivoted to the first position via the sensor drive mechanism 2248.

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

  In the next step S405, the optical sensor 2245 is moved to the m-th detection position via the sensor drive 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 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 negative and the process moves to step S415.

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

  Subsequently, the processes of 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 levels of the light receiver 13 is S1 ′, the average value of the output levels of the light receiver 14 is S2 ′, and the average value of the output levels 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 relevance ratio RH is calculated for each brand using the following equation (1). The relevance ratio RV is calculated using the equation).

  In the next step S421, in the precision ratio RH and the precision ratio RV calculated for each grade, a grade in which either the precision rate RH or the precision rate RV is the largest is extracted, and the extracted grade is used as recording paper M It will be a brand name.

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

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 device 2090 in 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 pivoted to the second position via the sensor drive mechanism 2248. The following is the same as the first processing method.

  That is, the second processing method is different 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 using the flowcharts of FIGS. 17 and 18. These flowcharts correspond to a series of processing algorithms executed by the CPU of the printer control unit 2090 in the third processing method.

  In the first step S501, the optical sensor 2245 is pivoted to the first position via the sensor drive mechanism 2248.

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

  In the next step S505, the optical sensor 2245 is moved to the m-th detection position via the sensor drive 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 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 negative 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.

  Subsequently, the processing of steps S505 to S515 is repeated until the determination in step S513 is affirmed.

  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 pivoted to the second position via the sensor drive mechanism 2248.

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

  In the next step S525, the optical sensor 2245 is moved to the m-th detection position via the sensor drive 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 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 negative and the process moves 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 process of steps S525 to S535 is 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 this step S551, 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 levels of the light receiver 13 is S1H ', the average value of the output levels of the light receiver 14 is S2H', and the average value of the output levels 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 levels of the light receiver 13 is S1V ', the average value of the output levels of the light receiver 14 is S2V', and the average value of the output levels of the light receiver 15 is S3V '.

  In the next step S555, with reference to the brand-specific output level data stored in the ROM of the printer control device 2090, the relevance ratio RH is calculated using the following equation (3) for each brand, and the following (4 The relevance ratio RV is calculated using the equation (1), the relevance ratio RH 'is calculated using the following equation (5), and the accuracy rate RV' is computed using the following equation (6).

  In the next step S 557, in the precision ratio RH, the precision ratio RV, the precision ratio RH ′ and the precision ratio RV ′ calculated for each stock, the stock with the largest one of RH × RV and RH ′ × RV ′ is extracted The extracted brand is taken as the grade of the recording paper M.

  In the next step S559, the identified brand of 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 of FIG. This flowchart corresponds to a series of processing algorithms executed by the CPU of the printer control device 2090 in the fourth processing method. As shown in FIG. 20, the rotational 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 sheet M is α (0 <α <90) is It is called the third attitude. The brand-specific output level data includes the output level S1A of the light receiver 13 in the third attitude, the output level S2A of the light receiver 14, and the output level S3A of the light receiver 15 (see FIG. 21). ). Here, although α = 45 ° as an example, it is not limited to this.

  In the first step S601, the optical sensor 2245 is pivoted to the third position via the sensor drive mechanism 2248.

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

  In the next step S605, the optical sensor 2245 is moved to the m-th detection position via the sensor drive mechanism 2248.

  In the next step S 607, 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 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 negative and the process moves to step S615.

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

  Subsequently, the processes of steps S605 to S615 are repeated until the determination in step S613 is affirmed.

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

  In the next step S619, the brand-specific output level data stored in the ROM of the printer control device 2090 is referred to, and for each grade, the relevance ratio RH is calculated using the following equation (7). The relevance ratio RV is calculated using the equation (6), and RA is calculated using the following equation (9).

  In the next step S621, for the precision ratio RH, the precision ratio RV, and the precision ratio RA calculated for each brand, the brand with one of the maximum is extracted, and the extracted brand is used as the grade of the recording paper M.

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

  When receiving a print job request from the user, the printer control device 2090 reads out the grade of the recording paper stored in the RAM, and obtains from the development / transfer table the development conditions and transfer conditions optimal for the grade of the recording paper. .

  Then, the printer control device 2090 controls the developing device and the transfer device of each station according to the optimum developing condition and the transfer condition. For example, it controls the transfer voltage and the toner amount. Thereby, a high quality image is formed on the recording sheet.

  By the way, in the recording paper, the orientation of the fibers constituting the recording paper is generated due to the manufacturing method. The orientation of the fibers is also referred to as "flow line" and is formed along the flow direction of the recording paper in the manufacturing process. Therefore, even if the recording paper is the same, the reflection characteristics may be different 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 on the surface orthogonal to the surface of the recording paper M is β (°).

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

  In the present embodiment, the brand-specific output level data 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, it is possible to simultaneously obtain both the grade of the recording paper M to be discriminated and the flow direction.

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

  Also in the second processing method, the flow direction is parallel to the L direction when the relevance ratio RH is maximum, and the flow direction is the L direction when the relevance ratio RV is maximum. It can be judged that they are orthogonal to

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

  As apparent from the above description, in the color printer 2000 according to the present embodiment, the processing device and the adjustment device of the present invention are configured by the printer control device 2090, and the database of the present invention is configured by output level data by brand. ing.

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

  The light source 10 emits S-polarized light, the light receiver 13 mainly receives surface regular reflection light, the light receiver 14 receives P polarization component contained in the internal diffuse reflection light, and the light receiver 15 performs surface diffusion reflection It is arranged to mainly receive light.

  Further, in the ROM of the printer control device 2090, when the optical sensor 2245 is in the first posture or in the second posture, the output of each light receiver measured in advance for a plurality of types of recording paper whose brand is known The level is stored as output level data by stock.

  Then, the printer control device 2090 performs the paper type discrimination process of the recording paper when the color printer 2000 is powered on, when the recording paper is supplied to the paper feed tray 2060, and the like. In this paper type discrimination process, the printer control device 2090 irradiates the light from the light source 10 onto the recording paper M to be discriminated, and determines the output level of each light receiver, and then refers to the brand-specific output level data, The relevance ratio RH and the relevance ratio RV are calculated for each brand, and the brand whose recording paper M is the brand with the maximum value of either is used.

  In this case, since the paper type discrimination in consideration of the flow direction is performed, the paper type discrimination can be performed more accurately than in the related art. In the conventional paper type discrimination process, no consideration has been given to the flow direction.

  Further, in the present embodiment, since a surface emitting laser array is used as a light source, a polarization filter for obtaining linearly polarized light is unnecessary. Furthermore, in the surface emitting laser array, high-density integration of a plurality of light emitting units, which is difficult with conventionally used LEDs and the like, is possible. In this case, a compact light source having a plurality of light emitting units can be realized. Further, since all the laser beams can be concentrated in the vicinity of the optical axis of the collimating lens, it is possible to make the plurality of beams substantially parallel by making the incident angle constant. In this case, an inexpensive collimating optical system can be used. Therefore, downsizing and cost reduction of the optical sensor can be achieved.

  In addition, the printer control device 2090 simultaneously turns on a plurality of light emitting units of the surface emitting laser array. For this reason, it is possible to increase the light amount of the P-polarization component of the internal diffuse reflection light.

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

  Then, the printer control device 2090 specifies the brand of the recording paper from the output signals of the three light receivers. That is, by adding information on the internal state of the recording paper, the discrimination level of the paper type is improved to the level of the brand which was conventionally difficult.

  In addition, since the component configuration is simple without combining a plurality of types of sensors, a small-sized optical sensor can be realized at low cost.

  Therefore, according to the optical sensor 2245, it is possible to specify an object with high accuracy with a simple configuration.

  The color printer 2000 according to the present embodiment includes the optical sensor 2245. As a result, high-quality images can be formed without increasing the cost and size. Furthermore, the failure of printing due to the inconvenience and setting error that must be manually set in the prior art is eliminated.

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

  Moreover, although the said embodiment demonstrated the case where the detection position was plural, it is not limited to this.

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

  Further, in the above embodiment, the case of setting the optimum developing condition and transfer condition based on the grade of the recording paper has been described, but the present invention is not limited to this. Optimal development conditions and transfer conditions may be set based on at least one of the grade of the recording paper and the flow direction.

  Further, in the above embodiment, at least a part of the process 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.

  Further, in the above embodiment, the sensor drive mechanism 2248 is described as being composed of the base 2248a, the shaft 2248b, the guide 2248c, the first motor 2248d, the table 2248e, the table shaft 2248f, the second motor 2248g, etc. It is not limited to

  Further, in the above embodiment, the case where the light irradiated to the recording paper is the S-polarization has been described. However, the present invention is not limited to this, and the light irradiated to the recording paper may be P-polarization. However, in this case, instead of the polarizing filter 16, a polarizing filter for transmitting S-polarized light is used, and the light receiver 14 receives the S-polarized light component contained in the internal diffuse reflection light.

  Further, in the above-described embodiment, in the plurality of light emitting units of the surface emitting laser array, at least a part of the light emitting unit intervals may be different from the other light emitting unit intervals (see FIG. 24). That is, the intervals 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 case where linearly polarized light is emitted from the light source 10 has been described in the above embodiment, the present invention is not limited to this. However, in this case, as shown in FIG. 25 as an example, a polarization filter 26 for making the irradiation light S-polarized is required.

  In the above embodiment, it is more preferable that a condenser lens be disposed in front of each light receiver. In this case, fluctuations in the amount of light received by each light receiver can be reduced.

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

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

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

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

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

  Further, although the case where the image forming apparatus has four photosensitive drums has been described in the above embodiment, 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 in which the toner image is transferred from the photosensitive drum to the recording paper via the transfer belt has been described. However, the present invention is not limited to this. The toner image is recorded from the photosensitive drum The image forming apparatus may be directly transferred to paper.

  The optical sensor 2245 is also applicable to an image forming apparatus that sprays ink on a recording sheet to form an image.

  DESCRIPTION OF SYMBOLS 10 ... Light source, 12 ... Collimator lens, 13 ... Photodetector (1st photodetector) 14 ... Photodetector (2nd photodetector), 15 ... Photodetector (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 Photosensitive drum (image carrier) 2032a , 2032b, 2032c, 2032d, ... charging devices, 2033a, 2033b, 2033c, 2033d ... developing rollers, 2040 ... transfer belts, 2042 ... transfer rollers, 2050 ... fixing devices, 2090 ... printer control devices (processing devices, adjustment devices), 2245 ... Optical sensor, 2248 ... Sensor drive mechanism.

JP, 2005-156380, A JP 10-160687 A Japanese Patent Application Laid-Open No. 2006-062842 Unexamined-Japanese-Patent No. 11-249353 gazette JP 2012-127937 A Patent No. 3577713 gazette Patent No. 2801144 gazette Patent No. 3734247 gazette

Claims (7)

An optical sensor having a light source, and a plurality of light detectors that receive light emitted from the light source and specularly reflected by the object and diffusely reflected light;
In regard to a plurality of types of objects whose types are known and different from each other, the incident direction of the light from the optical sensor is in advance a first direction with respect to the object and a second direction perpendicular to the first direction A database including output data of the plurality of photodetectors acquired in two directions;
The light from the light source is irradiated to a plurality of positions of the target from the first and second directions while moving relative to the target of unknown type , and the light is obtained for each of the positions. And a processing device for collating the output data of the plurality of detected light detectors with the database to determine the type of the object whose type is unknown. The processing device calculates, for each of the types in the database, a relevance ratio representing the degree of match with the output data when the type is an unknown object for each detector, and the type based on the relevance ratio. The type determination system according to claim 1, wherein the type of the unknown object is determined. The type determination system according to claim 2 , wherein the object is paper, and the processing device further determines a flow direction of the object whose type is unknown based on the relevance ratio. The type determination system according to any one of claims 1 to 3 , wherein the light source includes a surface emitting laser array. The type discrimination system according to any one of claims 1 to 4 , wherein the object is paper, and the first direction is a direction parallel to the flow direction. In an image forming apparatus for forming an image on an object,
An optical sensor having a light source, and a plurality of light detectors that receive light emitted from the light source and specularly reflected by the object and diffusely reflected light;
In regard to a plurality of types of objects whose types are known and different from each other, the incident direction of the light from the optical sensor is in advance a first direction with respect to the object and a second direction perpendicular to the first direction A database including output data of the plurality of photodetectors acquired in two directions;
The light from the light source is irradiated to a plurality of positions of the target from the first and second directions while moving relative to the target of unknown type , and the light is obtained for each of the positions. A processing device which collates the output data of the plurality of detected light detectors with the database and determines the type of the object whose type is unknown;
An adjusting device configured to adjust an image forming condition based on a determination result of the processing device. The object is paper,
The image forming apparatus according to claim 6 , wherein the adjusting device adjusts the image forming condition based on at least one of the brand of the object and the flow direction.

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