JP2019182659A - Data processing device and image formation device - Google Patents

Abstract

To provide a data processing device that can identify the position of a recording medium on the transportation route.SOLUTION: A controlling part 6 causes a light emission part 71 to irradiate with specific line-like light with a specific light amount when a recording medium is not yet transported, and obtains a plurality of pieces of second data that change the level according to the incident light amount onto a plurality of light receiving parts 72 based on the specific line-like light. The controlling part 6 obtains the maximum level and the minimum level from the level that the plurality of pieces of the second data have. The controlling part 6, in advance, stores thereon property data that show the level of the plurality of pieces of the second data for the amount of the line-like light that is radiated onto the recording medium when foreign material is not attached to the light emitting part or the plurality of light receiving parts. The controlling part 6 derives a set light amount of the line-like light based on the threshold, the maximum level, the minimum level, and the property data, and causes the light emission part 71 to irradiate with the line-like light with the specific light amount.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a data processing apparatus that specifies the position of a recording medium on a conveyance path, and an image forming apparatus including the data processing apparatus.

  In an image forming apparatus, a light source and a plurality of light receiving elements may be provided in a conveyance path through which an unprinted recording medium is conveyed. The light source emits linear light extending in the main scanning direction to the recording medium conveyed along the conveyance path. The plurality of light receiving elements are opposed to the light source across the transport path, and receive linear light transmitted through the recording medium. The plurality of light receiving elements output data indicating the amount of light incident thereon to a data processing device such as a CPU. The data is sequentially output line by line in the main scanning direction. The data processing device performs shading correction on input data (see, for example, Patent Document 1).

JP 2004-228654 A

  The data processing apparatus may specify a position of the recording medium in the conveyance path and adjust a position of an image formed on the recording medium. For this position adjustment, it is conceivable to use the shading corrected data. The shading correction requires reference data indicating a reference value for a specific color (white, etc.). Considering that the characteristics of the light source and the light receiving element change over time, it is preferable that the reference data is acquired after the image forming apparatus starts operating on the user side.

  However, if foreign matter (for example, dust or paper dust) adheres to the light source or the plurality of light receiving elements after the operation of the image forming apparatus starts, the accuracy of the reference data decreases. As a result, the position of the recording medium in the transport path may not be accurately specified.

  An object of the present invention is to provide a data processing apparatus and an image forming apparatus capable of accurately specifying the position of an unprinted recording medium in a conveyance path.

  A data processing apparatus according to one aspect of the present invention includes a binarization unit, a position specifying unit, a first light emission control unit, a data acquisition unit, a level acquisition unit, a characteristic storage unit, and a light amount derivation unit. And a second light emission control unit. The binarization unit is predetermined with a plurality of first data whose levels change according to the amounts of incident light on the plurality of light receiving units based on linear light emitted from the light emitting unit toward the recording medium being conveyed. Binarization processing is performed with a threshold value, and binarized data is generated. The position specifying unit specifies the position of the recording medium based on each of the binarized data. The first light emission control unit causes the light emitting unit to emit specific linear light having a specific light amount at a timing when the recording medium is not conveyed. The data acquisition unit acquires a plurality of second data whose levels change according to the amounts of incident light on the plurality of light receiving units based on the specific linear light. The level acquisition unit acquires a maximum level and a minimum level from the levels of the plurality of second data. In the characteristic storage unit, the level of the plurality of second data with respect to the amount of linear light emitted from the light emitting unit toward the recording medium when no foreign matter is attached to the light emitting unit or the plurality of light receiving units. Is stored in advance. The light amount deriving unit derives a set light amount of the linear light based on the threshold value, the maximum level, the minimum level, and the characteristic data. The second light emission control unit emits the linear light having the set light amount from the light source.

  An image forming apparatus according to another aspect of the present invention includes a light emitting unit, a plurality of light receiving units, a binarizing unit, a position specifying unit, an image forming unit, a first light emission control unit, and a data acquisition unit. A level acquisition unit, a characteristic storage unit, a light amount derivation unit, and a second light emission control unit. The light emitting unit emits linear light toward the recording medium being conveyed. The plurality of light receiving units output a plurality of first data whose levels change according to the amount of incident light based on the linear light. The binarization unit generates binarized data by binarizing the plurality of first data with a predetermined threshold value. The position specifying unit specifies the position of the recording medium based on each of the binarized data. The image forming unit forms an image on the recording medium based on the position. The first light emission control unit causes the light emitting unit to emit specific linear light having a specific light amount at a timing when the recording medium is not conveyed. The data acquisition unit acquires a plurality of second data whose levels change according to the amounts of incident light on the plurality of light receiving units based on the specific linear light. The level acquisition unit acquires a maximum level and a minimum level from the levels of the plurality of second data. In the characteristic storage unit, the level of the plurality of second data with respect to the amount of linear light emitted from the light emitting unit toward the recording medium when no foreign matter is attached to the light emitting unit or the plurality of light receiving units. Is stored in advance. The light amount deriving unit derives a set light amount of the linear light based on the threshold value, the maximum level, the minimum level, and the characteristic data. The second light emission control unit emits the linear light having the set light amount from the light source.

  According to the present invention, the position of the recording medium in the main scanning direction in the transport path can be accurately specified.

FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a main part of the image forming apparatus. FIG. 3 is a schematic diagram illustrating input / output characteristics of a plurality of light receiving units. FIG. 4 is a schematic diagram showing characteristic data stored in the characteristic storage unit shown in FIG. FIG. 5 is a flowchart showing a procedure of processing for deriving the set light amount by the control unit shown in FIG. FIG. 6 is a schematic diagram showing the set light amount derivation process shown in FIG. FIG. 7 is a flowchart showing a processing procedure of image formation by the control unit shown in FIG. FIG. 8 is a schematic diagram illustrating second data in a state where no foreign matter is attached to the light emitting unit and the plurality of light receiving units illustrated in FIG. 5. FIG. 9 is a schematic diagram illustrating second data (before derivation of the set light amount) in a state where foreign matter is attached to the light emitting unit and the plurality of light receiving units illustrated in FIG. 5. FIG. 10 is a schematic diagram illustrating second data (after derivation of the set light amount) when foreign matter is attached to the light emitting unit and the plurality of light receiving units illustrated in FIG. 5.

  Hereinafter, each embodiment of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

  In FIG. 1, arrows X, Y, and Z indicate the left-right direction, front-rear direction, and up-down direction of the image forming apparatus 100.

  In FIG. 1, an image forming apparatus 100 is a copying machine, a printer, a facsimile machine, a multifunction machine, or the like. The multifunction machine has a copy function, a print function, a facsimile function, and the like.

  Specifically, the image forming apparatus 100 is an ink jet printer, and forms an image on the recording medium P using ink based on image data by an ink jet method. The image data is sent from an information processing apparatus or the like that is communicably connected to the image forming apparatus 100. The image data may be sent from an image reading device (not shown) included in the image forming apparatus 100. Note that the image forming apparatus 100 may form an image on the recording medium P using toner based on the image data by an electrophotographic method other than the ink jet method.

  The image forming apparatus 100 includes a housing 1, a storage unit 2, a transport unit 3, an image forming unit 4, a discharge unit 5, a control unit 6, and a light detection unit 7.

  The housing 1 includes an exterior body and a frame of the image forming apparatus 100. The housing 1 accommodates the accommodating portion 2, the conveying portion 3, and the image forming portion 4.

  The container 2 is a paper feed cassette. The accommodating portion 2 is provided at a position closer to the lower side in the housing 1. The accommodating portion 2 is attached to the housing 1 so as to be freely inserted and removed in the front-rear direction. An unprinted recording medium P can be stacked in the storage unit 2. The recording medium P has a rectangular main surface on which an image is formed. When the recording medium P is stacked in the storage unit 2, the first side of the main surface is orthogonal to the conveyance direction D1 of the recording medium P. In the following description, a direction parallel to the first side is referred to as a main scanning direction D2. In the present embodiment, the transport direction D1 is parallel to the left-right direction, and the main scanning direction D2 is parallel to the front-rear direction.

  A plurality of types of recording media P having different light transmittances can be loaded in the storage unit 2. Specifically, the plurality of types of recording media P include plain paper, recycled paper, thin paper, or thick paper having different basis weights. The light transmittance is substantially determined by the basis weight of the recording medium P because the color of the recording medium P is often white.

  The storage unit 2 can be loaded with a plurality of sizes of recording media P having different first side lengths.

  The transport unit 3 includes an upstream transport unit 3A and a downstream transport unit 3B.

  The upstream side transport unit 3A includes a pickup roller 31A, a separation roller pair 32A, a transport roller pair 33A, a registration roller pair 34A, a first guide unit 35A, a transport path 36A, and a second guide unit 37A. Including.

  The pickup roller 31A, the separation roller pair 32A, the conveyance roller pair 33A, the registration roller pair 34A, the first guide portion 35A, the conveyance path 36A, and the second guide portion 37A are arranged in the main scanning direction D2 rather than the maximum length of the first side. Has a long shape. Each roller included in the pickup roller 31A, the separation roller pair 32A, the transport roller pair 33A, and the registration roller pair 34A has a cylindrical shape.

  The upstream conveyance unit 3A picks up the recording medium P from the storage unit 2 one by one and sends it out to the first guide unit 35A. The recording medium P is conveyed toward the image forming unit 4 through the first guide part 35A, the conveyance path 36A, and the second guide part 37A. The first guide part 35A, the conveyance path 36A, and the second guide part 37A are examples of the conveyance path in the present invention. The upstream transport unit 3A guides the recording medium P to the registration roller pair 34A that is provided above the storage unit 2 by the separation roller pair 32A and the transport roller pair 33A. The recording medium P comes into contact with the registration roller pair 34A and stops temporarily. The registration roller 34A starts to rotate under the control of the control unit 6, and sends the recording medium P to the second guide unit 37A provided between the upstream transport unit 3A and the downstream transport unit 3B.

  The downstream-side transport unit 3B is provided in the housing 1 so as to be spaced above the housing unit 2. Further, the downstream side transport unit 3B is provided on the left side of the second guide unit 37A. The downstream transport unit 3B includes a tension roller 31B, a drive roller 32B, a first auxiliary roller 33B, a second auxiliary roller 34B, a transport belt 35B, an adsorption roller 36B, and a suction unit 37B.

  The tension roller 31B, the driving roller 32B, the first auxiliary roller 33B, the second auxiliary roller 34B, and the suction roller 36B have a cylindrical shape that is longer in the main scanning direction D2 than the maximum length of the first side.

  The tension roller 31B is provided to be separated from the second guide portion 37A in the left direction. The drive roller 32B is provided so as to be separated from the tension roller 31B in the left direction. The upper end positions of the tension roller 31B and the drive roller 32B substantially coincide with the vertical position of the nip formed by the registration roller pair 34A.

  The first auxiliary roller 33B is provided to be spaced diagonally to the left and below the tension roller 31B. The second auxiliary roller 34B is provided to be separated from the first auxiliary roller 33B in the left direction and to be separated from the driving roller 32B in the diagonally downward direction to the right.

  The conveyor belt 35B is an endless belt and has a width larger in the main scanning direction D2 than the maximum length of the first side. The conveyor belt 35B is stretched around the tension roller 31B, the driving roller 32B, the first auxiliary roller 33B, and the second auxiliary roller 34B. A large number of through holes (not shown) that penetrate from the outer peripheral surface side to the inner peripheral surface side are formed in the entire circumferential direction of the transport belt 35B.

  The drive roller 32 </ b> B rotates under the control of the control unit 6. Thereby, the conveyance belt 35B rotates. Further, the tension roller 31B, the first auxiliary roller 33B, and the second auxiliary roller 34B are driven and rotated by the rotation of the transport belt 35B. Thereby, the conveyance belt 35B travels between the upper ends of the tension roller 31B and the driving roller 32B in a direction indicated by an arrow D3 in FIG. 1 (hereinafter referred to as a traveling direction D3). The traveling direction D3 is parallel to the left-right direction and is a direction from the registration roller pair 34A toward the discharge roller pair 51 (that is, the left direction).

  The suction roller 36B faces the tension roller 31B with the conveyance belt 35B interposed therebetween, and abuts on the outer peripheral surface of the conveyance belt 35B from above. The recording medium P that has passed through the second guide portion 37A is sent between the suction roller 36B and the conveyance belt 35B. The suction roller 36B presses the recording medium P against the outer peripheral surface of the transport belt 35B and sends it out in the downstream direction of the traveling direction D3.

  The suction unit 37B is disposed directly below the inner peripheral surface of the transport belt 35B between the suction roller 36B and the drive roller 32B. The suction part 37B sucks air from the numerous through holes of the transport belt 35B. As a result, the recording medium P is conveyed from the suction roller 36B to the downstream side in the traveling direction D3 while being in close contact with the outer peripheral surface of the conveying belt 35B. Note that the suction unit 37B may electrostatically suck the recording medium P and bring it into close contact with the transport belt 35B.

  The image forming unit 4 includes four recording heads 41. The four recording heads 41 correspond to a plurality of predetermined colors. The plurality of colors are black, cyan, magenta and yellow. The number of recording heads 41 may be one or more.

  Each recording head 41 has a box shape longer in the main scanning direction D2 than the maximum length of the first side. Each recording head 41 is juxtaposed along the left-right direction above the suction portion 37B with the conveyance belt 35B interposed therebetween. Each recording head 41 is disposed away from the outer peripheral surface of the conveyance belt 35B. At the lower end of each recording head 41, a large number of nozzles that eject ink are arranged in the main scanning direction D2.

  The recording medium P is transported to the downstream side in the traveling direction D3 by the transport belt 35B that travels directly under each recording head 41. Each recording head 41 is driven by the control unit 6 and ejects ink of a corresponding color from the plurality of nozzles toward the recording medium P that passes directly under the recording head 41. Accordingly, the image forming unit 4 forms an image based on the image data on the recording medium P using the four recording heads 41.

  As a method for ejecting ink by each recording head 41, a piezo method for ejecting the ink using a piezo element or the like, or a thermal method for ejecting the ink by generating bubbles by heating can be considered.

  The discharge unit 5 includes a discharge roller pair 51 and a discharge tray 52, and discharges the recording medium P on which the image is formed from the housing 1 to the outside of the image forming apparatus 100 as a printed matter.

  The control unit 6 is an example of a data processing device in the present invention. The control unit 6 includes a CPU, a ROM, a RAM, and a nonvolatile memory, executes a program stored in the ROM or the like, and comprehensively controls image formation on the recording medium P by the image forming apparatus 100. The control unit 6 may include an electronic circuit such as a microcomputer, an ASIC (Application Specific Integrated Circuit), or a DSP (Digital Signal Processor) instead of the CPU.

  The light detection unit 7 is a light transmission type CIS (Contact Image Sensor), and includes a light emitting unit 71 and a plurality of light receiving units 72.

  The light emitting unit 71 and the plurality of light receiving units 72 are provided at a position near the image forming unit 4 in the conveyance path (that is, the first guide unit 35A, the conveyance path 36A, and the second guide unit 37A) of the recording medium P. The distance from the light detection unit 7 to the image forming unit 4 can be reduced, and the shift of the recording medium P in the main scanning direction D2 can be reduced during this period. As a result, the image forming unit 4 can accurately form an image at the position specified by the position specifying unit 6H.

  Specifically, the light emitting unit 71 and the plurality of light receiving units 72 are provided in the second guide unit 37A. A light irradiation point EP1 extending in the main scanning direction D2 is determined at a predetermined position in the second guide portion 37A. The light emitting part 71 and the light receiving part 72 are provided in the second guide part 37A so as to face each other in the vertical direction across the light irradiation point EP1.

  The light emitting unit 71 has a rod-like shape that is long in the main scanning direction D2. The light emitting unit 71 generates linear light longer in the main scanning direction D2 than the maximum length of the first side, and emits the light to the light irradiation point EP1. When the recording medium P is conveyed through the second guide portion 37A, the linear light is emitted from the light emitting unit 71 toward the recording medium P being conveyed. In this case, most of the linear light passes through the recording medium P and enters the plurality of light receiving portions 72.

  In addition, the light emission part 71 can be made into the light emitting element array arranged along the front-back direction Y. The light emitting unit 71 may include, instead of the light emitting element array, a light guide extending in the front-rear direction Y and a light emitting element provided at an end portion in the front-rear direction of the light guide.

  The plurality of light receiving portions 72 are a plurality of photodiodes or the like arranged along the main scanning direction D2. Light based on the linear light is incident on the plurality of light receiving portions 72 via a gradient index lens array (not shown). The plurality of light receiving units 72 generate a plurality of first data whose levels change according to the amount of light incident on the light receiving unit 72 and output the first data to the control unit 6.

  By the way, in the image forming apparatus 100, the control unit 6 specifies the position of the recording medium P in the main scanning direction D2 (hereinafter referred to as the main scanning direction position) on the transport path, and the image formed on the recording medium P is identified. The position in the main scanning direction is adjusted. For the position adjustment, so-called shading corrected first data may be used. However, the shading correction requires reference data indicating a reference value for a specific color (white, black, etc.). The reference data is colored with the specific color after starting the operation of the image forming apparatus 100 on the user side, not before the shipment of the image forming apparatus 100, considering the secular change of the light emitting unit 71 and the light receiving unit 72. It is desirable to generate using a reference plate or the like.

  However, if foreign matter (for example, dust or paper dust) adheres to the light emitting unit 71 and the plurality of light receiving units 72 after the operation of the image forming apparatus 100 is started, the accuracy of the reference data decreases. As a result, the control unit 6 may not be able to accurately specify the position in the main scanning direction of the recording medium P in the transport path.

  Therefore, the control unit 6 does not perform the shading correction on the first data to specify the main scanning direction position of the recording medium P, but performs the processing described below. Therefore, the image forming apparatus 100 further includes a display unit 8 as shown in FIG. The control unit 6 includes a first light emission control unit 6A, a data acquisition unit 6B, a level acquisition unit 6C, a characteristic storage unit 6D, a light amount derivation unit 6E, a second light emission control unit 6F, a binarization unit 6G, and a position specifying unit. 6H, a position controller 6I and a warning output unit 6J. Specifically, the control unit 6 executes the program to thereby obtain a first light emission control unit 6A, a data acquisition unit 6B, a level acquisition unit 6C, a characteristic storage unit 6D, a light quantity derivation unit 6E, and a second light emission control unit 6F. , Functions as a binarization unit 6G, a position specifying unit 6H, a position control unit 6I, and a warning output unit 6J.

  In FIG. 2, the display unit 8 is a liquid crystal display, for example, and indicates that the binarization processing by the binarization unit 6G is an error based on warning data (details will be described later) output from the warning output unit 6J. Display information.

  The first light emission control unit 6A causes the light emitting unit 71 to emit specific linear light having a specific light amount at a timing when the recording medium P is not conveyed on the conveyance path. The timing is preferably immediately after the image forming apparatus 100 is activated. Immediately after the startup, the image forming apparatus 100 is either immediately after power-on or immediately after the image forming apparatus 100 returns from the sleep mode. Thereby, it is possible to suppress the processing by the light amount deriving unit 6E from affecting the productivity of the image forming apparatus 100. The productivity is, for example, the number of printed products per unit time. The timing is not limited to immediately after activation, but may be after the image forming unit 4 has finished forming an image on the recording medium P and before the image is formed on the next recording medium P.

  The data acquisition unit 6B acquires a plurality of second data whose levels change according to the amounts of incident light on the plurality of light receiving units 72 based on the specific linear light. Here, when the foreign matter adheres to the light emitting unit 71 or the plurality of light receiving elements 72, incident light to the plurality of light receiving units 72 is attenuated by the foreign matter. Therefore, the level of the plurality of second data correlates with the adhesion amount of the foreign matter. Specifically, the level decreases as the amount of foreign matter attached increases.

  The level acquisition unit 6C acquires the maximum level and the minimum level from the levels of the plurality of second data.

  The characteristic storage unit 6 </ b> D is the nonvolatile memory included in the control unit 6. In the characteristic storage unit 6D, the plurality of second data for the light amount of the linear light emitted from the light emitting unit 71 toward the recording medium P when the foreign matter is not attached to the light emitting unit 71 or the plurality of light receiving units 72. Characteristic data indicating the level of the is stored in advance. Specifically, the characteristic data is stored in the nonvolatile memory before the image forming apparatus 100 is shipped (for example, at the manufacturing stage).

  The light emitting unit 71 starts the operation of the image forming apparatus 100 on the user side and then controls the control unit 6 to control the linear light toward any of a plurality of types of recording media having a plurality of different light transmittances. Eject below. The plurality of light transmittances are predetermined as described above. The characteristic data preferably indicates the levels of the plurality of second data with respect to the light amount of the linear light emitted from the light emitting unit 71 toward the recording medium P having the maximum light transmittance. If the characteristic data indicates the level of the plurality of second data with respect to the light amount of the linear light emitted toward the recording medium P having the light transmittance that is not the maximum, the recording with the light transmittance being the maximum. This is because when the linear light is emitted toward the medium P, an error is likely to occur in the binarization process.

  The light amount deriving unit 6E performs a light amount deriving process for deriving the set light amount of the linear light based on the threshold value used in the binarizing unit 6G, the maximum level, the minimum level, and the characteristic data.

  The second light emission control unit 6 </ b> F causes the linear light having the set light amount to be emitted from the light emitting unit 71.

  The linear light is emitted toward the recording medium P being conveyed through the conveyance path. The binarization unit 6G acquires a plurality of first data whose levels change according to the amounts of incident light on the plurality of light receiving units 72 based on the linear light from the plurality of light receiving units 72. The binarization unit 6G performs binarization processing on the plurality of first data at a predetermined threshold value T1 to generate binarized data.

  The position specifying unit 6H specifies the position of the recording medium P based on each of the binarized data. Specifically, the position is a position in the main scanning direction of the recording medium P at the light irradiation point EP1 (see FIG. 1) of the conveyance path.

  The position control unit 6I corrects the image data based on the position, and adjusts the formation position of the image on the recording medium P by the image. The position control unit 6I drives the image forming unit 4 based on the corrected image data. As a result, the image forming unit 4 forms an image on the recording medium P based on the position specified by the position specifying unit 6H.

  The warning output unit 6J outputs warning data indicating that the light amount derivation process is an error when the light amount derivation unit 6E cannot derive the set light amount of the linear light. The warning data is stored in advance in the nonvolatile memory or the like. Based on the warning data, the display unit 8 displays that the light amount derivation process is an error and notifies the user.

  Hereinafter, the processing procedure of the control unit 6 (that is, the data processing device) will be described in further detail with reference to FIGS.

  FIG. 3 shows input / output characteristic curves L11 of the plurality of light receiving units 72. The input / output characteristic curve L11 is divided into a linear region R1 and a saturation region R2. The linear region R1 is a range in which the incident light amount is from 0 to a predetermined light amount threshold value T2. The saturation region R2 is a range where the incident light amount exceeds the light amount threshold value T2. In the linear region R1, the output levels of the plurality of light receiving units 72 are proportional to the incident light amount. On the other hand, in the saturation region R2, the output levels of the plurality of light receiving units 72 are constant with respect to the incident light amount.

  FIG. 4 shows the output decrease rate K stored in advance in the characteristic storage unit 6D. The output decrease rate K is created based on an experiment or simulation performed before the image forming apparatus 100 is shipped. Specifically, the experimenter or the like operates the image forming apparatus 100 in a state in which the foreign matter is not attached to the light emitting unit 71 or the plurality of light receiving units 72, and is directed to the recording medium P having the maximum light transmittance. Then, the specific linear light having the specific light quantity L1 is emitted. Here, the specific light amount L1 is a light amount included in the linear region R1 of the input / output characteristic curve L11. The experimenter or the like measures the levels of the plurality of second data output from the plurality of light receiving units 72. The experimenter or the like obtains a level C1 representing each measurement level. The level C1 is a level of the plurality of second data corresponding to the specific light quantity L1, and can be an average value of each of the measurement levels. In addition, the level C1 may be the level of the second data output from a specific light receiving unit 72 among the plurality of light receiving units 72.

  The experimenter derives a level A1 corresponding to the specific light quantity L1 from the input / output characteristic curve L11. The level A1 is a level of the plurality of second data output from the plurality of light receiving units 72 when the recording medium P is not conveyed on the conveyance path.

  The experimenter further obtains K = C1 / A1 and stores it in the nonvolatile memory. K is an example of the characteristic data in the present invention, and specifically indicates the reduction rate of the plurality of second data output from the plurality of light receiving units 72 by the recording medium P having the maximum light transmittance. .

  FIG. 5 is a flowchart showing a procedure of processing executed by the control unit 6 when the set light amount is derived and stored. In FIG. 5, the control unit 6 determines whether or not the image forming apparatus 100 has just been started (step S1). Specifically, the control unit 6 determines whether it is immediately after the return from the sleep mode or the power-on. If the control unit 6 determines that it is not immediately after the start-up, it ends the processing of FIG. On the other hand, when the control unit 6 determines that it is immediately after the start-up, the process proceeds to step S2.

  In step S <b> 2, the control unit 6 functions as the first light emission control unit 6 </ b> A on the assumption that the recording medium P is not conveyed on the conveyance path immediately after the activation. The control unit 6 causes the specific linear light having the specific light amount L1 to be emitted to the light emitting unit 71 (step S2), and the process proceeds to step S3. The characteristic linear light propagates through the space in the second guide portion 37A, passes through the light irradiation point EP1 (see FIG. 1), and is incident on the plurality of light receiving portions 72. The plurality of light receiving units 72 output the plurality of second data to the control unit 6.

  In step S3, the control unit 6 functions as the data acquisition unit 6B, acquires the plurality of second data, and advances the process to step S4. Here, when the foreign matter adheres to the plurality of light receiving portions 72, the level of the plurality of second data changes according to the amount of the foreign matter attached to each of the plurality of light receiving portions 72.

  In step S4, the control unit 6 functions as the level acquisition unit 6C, and acquires the minimum level B1 and the maximum level B2 (see FIG. 6) from the levels of the plurality of second data. Then, the control part 6 advances a process to step S5.

  In step S5, the control unit 6 functions as the light amount deriving unit 6E and performs the light amount deriving process. Specifically, the control unit 6 first reads the output decrease rate K (known constant) from the characteristic storage unit 6D into a RAM or the like.

  Here, in FIG. 6, in addition to the input / output characteristic curve L11 (see FIG. 3), the level A1 and the level C1 (see FIG. 4), the minimum level B1, the maximum level B2, and the threshold value T1 are shown. FIG. 6 further shows a straight line L12 passing through the origin and the level C1, a straight line L13 passing through the origin and the minimum level B1, and a straight line D4 passing through the origin and the maximum level B2.

  The minimum level B1 and the maximum level B2 are included in a region sandwiched between the input / output characteristic curve L11 and the straight line L12. Specifically, the minimum level B1 and the maximum level B2 are on a straight line with the light amount L1 (that is, the specific light amount L1) in the region. The minimum level B1 is included in a position near the straight line L12 among the input / output characteristic curve L11 and the straight line L12, and the maximum level B2 is included in a position near the input / output characteristic curve L11.

  FIG. 6 further shows the set light amount of the linear light derived by the light amount deriving unit 6E as L2. The set light amount L2 is not necessarily included in the linear region R1 of the input / output characteristic curve L11, and may be included in the saturation region R2. Further, the set light quantity L2 does not necessarily have any value. Specifically, if the set light amount L2 is excessively increased, in the binarization process by the binarization unit 6G, the recording medium P passes through the light irradiation point EP1, but the plurality of second data All may exceed the threshold value T1. However, if the set light amount L2 is not sufficiently increased, the foreign matter and the recording medium P may not be accurately distinguished in the binarization process. Accordingly, the set light amount L2 is determined so as to satisfy the following conditions. Hereinafter, the condition of the set light amount L2 will be described.

  In FIG. 6, points A1 and C1 are points on the input / output characteristic curve L11 and the straight line L12 when the light amount is the specific light amount L1. The output levels indicated by the points A1 and C1 are known. The point A2 is a point indicating a level corresponding to the set light amount L2 on the straight line D5 passing through the origin and the point A1. The point C2 is a point indicating a level corresponding to the set light amount L2 on the straight line L12. Here, the point A2 is unknown because the set light amount L2 may be included in the saturation region R2. Point C2 is also unknown.

  Points B1 and B2 are points indicating the minimum level B1 and the maximum level B2 when the light amount is the specific light amount L1, respectively. Points B1 'and B2' are points indicating output levels in the case of the set light amount L2 on the straight line L13 and the straight line D4, respectively.

  In FIG. 6, since the point A1 and the point A2 are on the straight line D5 and the point C1 and the point C2 are on the straight line L12, the following expression (1) is established.

  C1 / A1 = C2 / A2 = K (1)

  Further, B1 / B2 = B1 '/ B2'. When A1≈B2 and A2≈B2 ′, the above expression (1) is transformed into the following expression (2). Since B2 and B2 'are the maximum level B2 in the plurality of second data and the maximum level B2' in the set light amount L2, they can be approximated to A1 and A2, respectively.

  C2 = A2 × K = (K × B2 × B1 ′) / B1 (2)

  The following equation (3) is obtained by modifying the above equation (2).

  B1 '= (C2 * B1) / (B2 * K) (3)

  By setting the set light amount L2 that satisfies the condition that C2 satisfies ≦ T1 and B1 ′ satisfies B1 ′> T1, the recording medium P passes through the light irradiation point EP1 and the plurality of second data All of them do not exceed the threshold value T1, and the foreign matter and the recording medium P can be accurately distinguished in the binarization process.

  Specifically, the light quantity deriving unit 6E obtains B1 ′ by substituting C2 (where C2 is a value satisfying C2 ≦ T1) into the above equation (3). C2 is a known value and is recorded in advance in the program or the like. The light amount deriving unit 6E determines a light amount satisfying the above condition as a set light amount L2, and stores it in the RAM or the like (step S5). From the viewpoint of low power consumption, it is preferable that the minimum light amount among the light amounts satisfying the above condition is determined as the set light amount L2. After step S5 is completed, the control unit 6 waits for the image data to be transmitted. If the set light amount L2 that satisfies the above conditions cannot be determined, the minimum set light amount L2 that satisfies B1 '> T1 may be stored in the RAM or the like.

  Next, the light amount deriving unit 6E determines whether or not the set light amount L2 has been derived by the light amount deriving process (step S6). In step S6, the light amount deriving unit 6E specifically determines whether or not the set light amount L2 has been determined in step S5. The light quantity deriving unit 6E ends the process of FIG. 5 when the set light quantity L2 can be derived. On the other hand, if the set light amount L2 cannot be determined in step S5, the light amount deriving unit 6E determines that the foreign matter is excessively attached to the light emitting unit 71 or the plurality of light receiving units 72, and the process proceeds to step S7. Proceed.

  In step S7, the control unit 6 functions as a warning output unit 6J and outputs the warning data to the display unit 8. The display unit 8 displays the warning data. Thereby, the user can know that the foreign matter is too attached to the light emitting unit 71 or the plurality of light receiving units 72. Then, the control part 6 complete | finishes the process of FIG.

  In FIG. 7, the control unit 6 determines whether or not the image data has been received after completing the processing of FIG. 5 (step S11). When determining that the image data has not been received, the control unit 6 returns the process to step S11. On the other hand, when determining that the image data has been received, the control unit 6 advances the process to step S12.

  The controller 6 starts the image formation (step S12). As a result, the recording medium P is picked up one by one from the storage unit 2 and is conveyed toward the image forming unit 4 in the conveyance path.

  Moreover, the control part 6 drives the light emission part 71 and the some light-receiving part 72 immediately after step S12 (step S13). In step S13, the control unit 6 functions as the second light emission control unit 6F. Specifically, the control unit 6 emits the linear light having the set light amount L2 in the RAM from the light emitting unit 71, and the process proceeds to step S14.

  In step S14, the control unit 6 functions as the binarization unit 6G, acquires the plurality of first data from the plurality of light receiving units 72, and performs binarization processing on the plurality of first data with a threshold T1. To generate binarized data.

  In step S15, the control unit 6 functions as the position specifying unit 6H, and detects the edge of the recording medium P in the main scanning direction D2 from each of the binarized data. By detecting the edge, the control unit 6 specifies the position in the main scanning direction of the recording medium P at the light irradiation point EP1 of the transport path. In addition, the control unit 6 can also specify the position in the main scanning direction of a hole (for example, a punch hole) that may be formed in the recording medium P (step S15). Then, the control part 6 advances a process to step S16.

  In step S <b> 16, the control unit 6 functions as a position control unit 6 </ b> I, corrects the image data based on the position in the main scanning direction, and adjusts the image formation position of the image on the recording medium P. In addition, the control unit 6 also performs correction such as deleting a portion corresponding to the position of the hole in the image data. Then, the control part 6 advances a process to step S17.

  In step S17, the control unit 6 drives the image forming unit 4 based on the corrected image data. As a result, an image based on the corrected image data is formed on the recording medium P. Thereafter, the control unit 6 ends the process of FIG.

  As shown in FIG. 8, the second data has a substantially constant level in the main scanning direction D2 in a state where the foreign matter is not attached to the light emitting unit 71 and the plurality of light receiving units 72. In this case, the binarizing unit 6G binarizes the first data with a predetermined threshold value T1, thereby generating binarized data capable of specifying the main scanning direction position of the recording medium P. be able to. In FIG. 8, the second data is denoted by reference numeral D6, and the first data is denoted by reference numeral D7.

  As shown in FIG. 9, in a state where the foreign matter is attached to the light emitting portion 71 and the plurality of light receiving portions 72, the level of the second data is lowered in the portion where the foreign matter is attached. If the processing of FIG. 5 is not executed due to such a level decrease, the binarizing unit 6G may change the position in the main scanning direction of the recording medium P even if the first data is binarized with the threshold value T1. There is a possibility that identifiable binarized data cannot be generated. In FIG. 9, the second data is denoted by reference numeral D8, and the first data is denoted by reference numeral D9.

  However, according to the present embodiment, the light amount deriving unit 6E derives the set light amount L2 that satisfies the above expression (3) under the condition of C2 ≦ T by the process of FIG. The light emitting unit 71 generates the linear light having the set light amount L2. Therefore, as shown in FIG. 10, the threshold value T1 is not changed, but the levels of the second data and the first data are increased. Specifically, the second data exceeds the threshold T1, but the output level corresponding to the recording medium P in the first data is equal to or less than the threshold T1. As a result, the binarizing unit 6G can generate binarized data that can specify the position of the recording medium P in the main scanning direction. In FIG. 10, the second data is denoted by reference numeral D10, and the first data is denoted by reference numeral D11.

100 Image forming apparatus 6 Control unit 6A First light emission control unit 6A
6B Data acquisition unit 6C Level acquisition unit 6D Characteristic storage unit 6E Light quantity derivation unit 6F Second light emission control unit 6G Binarization unit 6H Position specification unit 6I Position control unit 6J Warning output unit 71 Light emitting unit 72 Multiple light receiving units

Claims (10)

A plurality of first data whose levels change according to the amount of incident light to a plurality of light receiving units based on linear light emitted from the light emitting unit toward the recording medium being conveyed are binarized with a predetermined threshold value A binarization unit that performs processing to generate binarized data;
A position specifying unit for specifying the position of the recording medium based on each of the binarized data;
A first light emission control unit that emits specific linear light having a specific light amount to the light emitting unit at a timing when the recording medium is not conveyed;
A data acquisition unit that acquires a plurality of second data whose levels change according to the amount of light incident on the plurality of light receiving units based on the specific linear light;
A level acquisition unit that acquires a maximum level and a minimum level from the levels of the plurality of second data;
Characteristic data indicating the level of the plurality of second data with respect to the amount of linear light emitted from the light emitting unit toward the recording medium when no foreign matter is attached to the light emitting unit or the plurality of light receiving units is stored in advance. A characteristic storage unit,
A light amount deriving unit that performs a light amount deriving process for deriving a set light amount of the linear light based on the threshold value, the maximum level, the minimum level, and the characteristic data;
A second light emission control unit for emitting the linear light having the set light amount from the light emitting unit;
A data processing apparatus comprising: The characteristic data is a reduction rate of the plurality of second data output from the plurality of light receiving units by the recording medium,
When the threshold value is T1, the minimum level is B1, the maximum level is B2, and the reduction rate is K, the light amount deriving unit sets the set light amount satisfying the following expressions (1) and (2). To derive,
The data processing apparatus according to claim 1.
C2 ≦ T1 (1)
(C2 × B1) / (B2 × K)> T1 (2)
In the above formulas (1) and (2), C2 indicates a level corresponding to the set light amount. A warning output unit that outputs warning data indicating that the light amount deriving process is an error when the light amount deriving unit cannot derive the set light amount of the linear light;
The data processing device according to claim 1 or 2. The light emitting unit emits the linear light toward any one of a plurality of types of recording media having a plurality of predetermined and different light transmittances;
The characteristic data indicates the level of the plurality of second data with respect to the amount of linear light emitted from the light emitting unit toward the recording medium having the maximum light transmittance among the plurality of types of recording media.
The data processing apparatus according to claim 1. A light emitting unit that emits linear light toward the recording medium being conveyed;
A plurality of light receiving units for outputting a plurality of first data whose levels change according to the amount of light incident on the basis of the linear light;
A binarization unit that generates binarized data by binarizing the plurality of first data with a predetermined threshold;
A position specifying unit for specifying the position of the recording medium based on each of the binarized data;
An image forming unit that forms an image on the recording medium based on the position;
A first light emission control unit that emits specific linear light having a specific light amount to the light emitting unit at a timing when the recording medium is not conveyed;
A data acquisition unit that acquires a plurality of second data whose levels change according to the amount of light incident on the plurality of light receiving units based on the specific linear light;
A level acquisition unit that acquires a maximum level and a minimum level from the levels of the plurality of second data;
Characteristic data indicating the level of the plurality of second data with respect to the amount of linear light emitted from the light emitting unit toward the recording medium when no foreign matter is attached to the light emitting unit or the plurality of light receiving units is stored in advance. A characteristic storage unit,
A light amount deriving unit for deriving a set light amount of the linear light based on the threshold value, the maximum level, the minimum level, and the characteristic data;
A second light emission control unit for emitting the linear light having the set light amount from the light emitting unit;
An image forming apparatus comprising: A conveyance path through which the recording medium is conveyed toward the image forming unit;
The light emitting unit and the plurality of light receiving units are provided at a position near the image forming unit in the conveyance path.
The image forming apparatus according to claim 5. The timing is immediately after activation of the image forming apparatus.
The image forming apparatus according to claim 5. The characteristic data is a reduction rate of the plurality of second data output from the plurality of light receiving units by the recording medium,
When the threshold value is T1, the minimum level is B1, the maximum level is B2, and the reduction rate is K, the light amount deriving unit sets the set light amount satisfying the following expressions (1) and (2). To derive,
The image forming apparatus according to claim 5.
C2 ≦ T1 (1)
(C2 × B1) / (B2 × K)> T1 (2)
In the above formulas (1) and (2), C2 indicates a level corresponding to the set light amount. A warning output unit that outputs warning data indicating that the light amount deriving process is an error when the light amount deriving unit cannot derive the set light amount of the linear light;
The image forming apparatus according to claim 5. The light emitting unit emits the linear light toward any one of a plurality of types of recording media having a plurality of predetermined and different light transmittances;
The characteristic data indicates the level of the plurality of second data with respect to the amount of linear light emitted from the light emitting unit toward the recording medium having the maximum light transmittance among the plurality of types of recording media.
The image forming apparatus according to claim 5.

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