JP2019080327A - Image reading device, image forming apparatus, and image forming system - Google Patents

Abstract

To provide an image reading device that can perform image correction with high accuracy, an image forming apparatus, and an image forming system.SOLUTION: An image reading device comprises: a reading device 55 that reads a sheet; a backing 80 that is arranged opposite to the reading device and is formed with an opposite surface opposite to the reading device; and a switching control unit 111 that switches the color of the surface formed on the backing opposite to the reading device to any one of black and white on the basis of a moment at which the reading device reads the sheet. A formation range of a patch formed on the sheet is determined on the basis of a position of a nip that reduces looseness of the sheet within an allowable range, switching time required for the switching control unit to switch the color of the opposite surface to white, and a conveyance speed at which the sheet is conveyed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image reading apparatus, an image forming apparatus, and an image forming system.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus is known as a multifunction peripheral (MFP) having a combination of functions such as a printer and a copier. Among such image forming apparatuses, an on-demand type image forming apparatus is required to maintain image quality comparable to offset printing. However, under the present circumstances, the image formed by the electrophotographic method has lower color reproducibility than the image formed by the offset printing. Therefore, in order to improve color reproducibility, various systems have been developed to create color profiles more quickly and easily in color measurement and to automate adjustment work.

  Among the adjustment operations described above, in order to adjust the absolute value of color, there is one in which a colorimeter for measuring the spectral reflectance is disposed in line to correspond. As a characteristic of this colorimeter, there is a possibility that the color measurement accuracy may deteriorate due to the change in height of the sheet. Therefore, the colorimeter is fixedly disposed at a position where the central portion (main direction) of the sheet is measured, in which the behavior of the sheet is stable and the imaging engine performance is also stable.

  Further, since the colorimeter is a spot measurement, it is configured to be able to measure an image of the full width of the sheet by combining with a CCD line sensor (scanner). Since the CCD line sensor can not guarantee the absolute value of color, by measuring and correlating the same patch as the CCD line sensor with the colorimeter, the absolute value of the color is guaranteed by measuring the patch of the paper with the colorimeter I am

  Moreover, in order to guarantee the absolute value of a color, the backing used as a white surface is installed in the opposing surface which opposes a colorimeter. Thus, the influence of the color of the backing is eliminated.

  By the way, when performing the in-line patch reading without stopping the conveyance of the sheet, usually, the measurement of the color is started after the measurement timing of the patch on the sheet to be conveyed is determined. Therefore, some kind of trigger is required for timing detection to measure a patch. In order to determine this trigger, a reflective sensor that detects the leading edge of the sheet is used, or a dedicated sensor that measures a trigger patch is used.

  In this case, since a dedicated sensor is provided, the number of parts increases and the cost also increases. Furthermore, depending on the mounting accuracy, the position of the sensor may be changed, so that the detection accuracy may be lowered, and there is a risk of straddling patches. Therefore, there is one in which the leading patch doubles as a trigger by using the lightness difference between the lightness of the backing and the lightness of the leading patch as a trigger (see, for example, Patent Document 1). In this case, there is a method of enlarging the patches in the sub-scanning direction in order to compensate for the decrease in detection accuracy, but the number of patches that can be arranged on one sheet decreases and the number of sheets necessary for measurement increases. The burden on For example, depending on the contents of adjustment, when the number of patches is large, it will be 1000 patches or more.

  In addition, control of measuring the entire area without matching the patch and cutting out only the necessary part restricts the placement of the patch. In this case, patches are arranged so that colors having small differences in lightness are not adjacent to each other. As a result, the control for determining the patch arrangement configuration becomes complicated, which increases the number of development steps and is not realistic.

  Therefore, there is a type that detects the leading end of the sheet by the change in color when the leading end of the sheet enters the backing (see, for example, Patent Document 2). In this case, since the colorimeter also serves as a sensor for detecting the leading edge of the sheet, the error in the measurement position is reduced, and the measurement accuracy is improved. Alternatively, the leading edge of the sheet may be detected by a change in diffuse reflection light reflected by the backing (see, for example, Patent Document 3). Alternatively, the difference may be calculated by comparing the lightness L * of the spectral reflectance with the backing surface. In this case, the backing portion may be made to be a dark color such as black in order to increase the difference from the paper white of the paper.

  By the way, since the colorimeter measures the absolute value of color, it is preferable that the color of the backing be white, which does not affect the measurement. In addition, in order to obtain certification at a color certification organization, the color of the backing must be white. Therefore, there is one in which the color of the backing is configured to be switchable, and is usually white at the time of correction, and is black at the time of skew correction (see, for example, Patent Document 4).

  In addition, there is one in which the color of the backing is made high when detecting the front end of the sheet, and the color of the backing is made low when performing calibration (see, for example, Patent Document 5).

JP, 2014-165802, A Japanese Patent Application Laid-Open No. 6-130160 JP, 2014-1069, A JP, 2009-290800, A JP 2014-116676 A

  However, in the prior art as described in Patent Documents 1 to 5, the relationship between the variation in the height direction of the conveyed sheet and the formation range of the patch is not considered. In the colorimeter, the color reading accuracy largely fluctuates due to the fluctuation in the height direction of the sheet being conveyed. Therefore, the above-mentioned prior art can accurately measure the absolute value of color while accurately detecting the end of the sheet, but it is not in a measurement environment where it is possible to ensure the color reading accuracy with high accuracy. . Therefore, the above-mentioned prior art may not be able to perform highly accurate image correction.

  The present invention has been made to solve the conventional problems, and an object thereof is to provide an image reading apparatus, an image forming apparatus, and an image forming system capable of performing highly accurate image correction. It is.

  In order to achieve the above object, an image reading apparatus according to the present invention comprises: a reading apparatus for reading a sheet; a backing disposed opposite to the reading apparatus and having an opposing surface facing the reading apparatus; And a switching control unit configured to switch the color of the surface facing the reading device formed on the backing to either black or white based on an opportunity when the device reads the sheet. A patch formed on the sheet The forming range is the position of the nip for suppressing the slack of the sheet within the allowable range, the switching time until the switching control section switches the color of the facing surface to white, the transport speed at which the sheet is transported, It is characterized in that it is determined based on

  According to this image reading apparatus, it is possible to perform image correction with high accuracy.

  In the image reading apparatus according to the present invention, the nip may be formed on each of an upstream conveyance roller upstream of the reading apparatus and a downstream conveyance roller downstream of the reading apparatus. Is preferred.

  According to this image reading apparatus, it is possible to read the sheet in the area where the height variation of the sheet is small.

  Further, in the image reading apparatus according to the present invention, within the nip, a distance between an upstream nip formed by the upstream conveyance roller and a downstream nip formed by the downstream conveyance roller. Preferably, the formation range of the patch is determined.

  According to this image reading apparatus, the patch can be read in an area where the height variation of the sheet is small.

  Preferably, in the image reading apparatus according to the present invention, the shape and size of the patch are determined based on the reading range of the reading apparatus and the transport speed.

  According to this image processing apparatus, the number of sheets used can be reduced.

  In the image reading apparatus according to the present invention, the switching control unit switches the color of the facing surface to black when the reading apparatus reads any one of the leading end and the trailing end of the sheet. Is preferred.

  According to this image reading apparatus, the patch can be measured at the correct position.

  Further, in the image reading apparatus according to the present invention, an image position adjustment mark serving as a reference for adjusting the position of the image formed on the sheet is formed, and the image position adjustment mark is a tip portion of the sheet. The switching control is performed in the margin between the leading patch of the patches or in the margin between the trailing end of the sheet and the patch at the trailing end of the patch, The section switches the color of the opposite surface from black to white until the reading operation of the leading patch by the reading device is started, and the reading operation of the rear end portion of the sheet by the reading device is Preferably, the color of the opposite surface is switched from white to black before the start.

  According to this image reading apparatus, it is possible to accurately read the image position adjustment mark and the patch.

  In the image reading apparatus according to the present invention, preferably, the switching control unit switches the color of the facing surface to white when the reading apparatus reads the patch.

  According to this image reading apparatus, the absolute value of color can be measured accurately.

  Further, in the image reading apparatus according to the present invention, while the color of the facing surface is white, the formation range of the patch is determined within a transport distance in which the sheet is transported according to the transport speed. Is preferred.

  According to this image reading apparatus, it is possible to reduce the cost of paper and the colorimetry time of patches.

  Further, in the image reading device according to the present invention, the reading device is a spectrocolorimeter or a scanner, and the scanner is provided on the upstream side of the spectrocolorimeter, and along the width direction of the sheet, It is preferable to have a CCD line sensor that reads the sheet, and the reading result of the scanner is corrected based on the reading result of the spectrocolorimeter.

  According to this image reading apparatus, it is possible to shorten the time required for adjusting the color of the image formed on the sheet.

  Further, in order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus provided on the upstream side of the image reading apparatus described above, wherein the position of the nip, the switching time, and Based on the acquisition unit for acquiring the conveyance speed, the position of the nip acquired by the acquisition unit, the switching time, and the conveyance speed, the formation range of the patch to be formed on the sheet is determined And an image processing unit.

  According to this image forming apparatus, highly accurate image correction can be performed.

  Further, in the image forming apparatus according to the present invention, the image processing unit creates a color profile of the color of the image to be formed on the sheet based on the reading result of the sheet by the image reading apparatus. preferable.

  According to this image forming apparatus, the color adjustment operation of the image formed on the sheet can be made efficient.

  Further, in order to achieve the above object, an image forming system according to the present invention is characterized by comprising the image reading apparatus described above and the image forming apparatus described above.

  According to this image forming system, an image comparable to offset printing can be formed on a sheet.

  According to the present invention, highly accurate image correction can be performed.

FIG. 1 is a block diagram schematically showing a configuration of an image forming system according to the present embodiment. It is a figure showing an example of functional composition of an image formation system concerning this embodiment. It is a figure which shows the correspondence of the lightness L * in case the lightness difference of the adjacent patch 201 is small, and a measurement position. It is a figure which shows the correspondence of the brightness L * in case the brightness difference of adjacent patch 201 is large, and a measurement position. When reading the end of the paper P, it is a diagram showing the color of the surface facing the spectrocolorimeter 70 formed on the backing 80. When reading the patch 201 formed in the paper P, it is a figure which shows the color of an opposing surface with the spectrocolorimeter 70 formed in the backing 80. FIG. It is a figure which illustrates roughly the switching timing of the color of the opposing surface with the spectrocolorimeter formed in the backing. It is a figure which illustrates roughly the relationship between the switching timing of the color of the surface opposite to the spectrocolorimeter formed on the backing 80, and the position of the nip. It is a figure which illustrates in steps the relationship between the switching timing of the color of the opposing surface with the spectrocolorimeter formed on the backing and the position of the nip. FIG. 14 is a diagram schematically illustrating switching timing of the color of the surface facing the spectrocolorimeter 70 formed on the backing 80 when the mark for image position adjustment is added to the sheet P. 5 is a flowchart illustrating an operation example of color adjustment processing. 5 is a flowchart illustrating an operation example of color and image position adjustment processing.

  Hereinafter, although an embodiment of the present invention is described based on a drawing, the present invention is not limited to the following embodiment.

  FIG. 1 is a block diagram schematically showing the configuration of an image forming system according to the present embodiment. The image forming system includes an image forming apparatus 2 and an image reading apparatus 3. A sheet feeding device 1 is provided upstream of the image forming apparatus 2. At the downstream side of the image reading device 3, a sheet discharge device 4 is provided.

  The image forming apparatus 2 forms an image by, for example, an electrophotographic method, and arranges the plurality of photosensitive drums 11Y, 11M, 11C, and 11K in the longitudinal direction so as to face one intermediate transfer belt 15. It is a so-called tandem type color image forming apparatus that forms a full color image. The image forming apparatus 2 mainly includes a document reading device SC, four sets of image forming units 10Y, 10M, 10C, and 10K, and a fixing device 30.

  The document reader SC scans and exposes the image of the document by the optical system of the scanning exposure apparatus, reads the reflected light by the line image sensor, and thereby obtains an image signal. The image signal is subjected to processing such as A / D conversion, shading correction, and compression, and then input as a read value of the image. The image data to be input is not limited to the one read by the document reading device SC, but may be, for example, a personal computer connected to the image forming device 2, one received from another image forming device, or a semiconductor memory. It may be read from a portable recording medium.

  The four image forming units 10Y, 10M, 10C, and 10K include an image forming unit 10Y that forms an image of yellow (Y), an image forming unit 10M that forms an image of magenta (M), and an image of cyan (C). An image forming unit 10C to be formed and an image forming unit 10K to form an image of black (K). Each of the image forming units 10Y, 10M, 10C, and 10K includes a photosensitive drum 11Y, 11M, 11C, and 11K, a charging unit disposed around the photosensitive drum, an optical writing unit, a developing device, and a drum cleaner. .

  The surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K are uniformly charged by the charging unit, and a latent image is formed by the scanning exposure by the optical writing unit. The developing device develops the latent image on the photosensitive drums 11Y, 11M, 11C, and 11K by developing with toner. Thus, an image (toner image) of a predetermined color corresponding to any of yellow, magenta, cyan and black is formed on the photosensitive drums 11Y, 11M, 11C and 11K. The images formed on the photosensitive drums 11Y, 11M, 11C, and 11K are sequentially transferred to predetermined positions on the rotating intermediate transfer belt 15 by the primary transfer rollers.

  The image transferred onto the intermediate transfer belt 15 is transferred by the secondary transfer roller 16 to the sheet P transported at a predetermined timing by the sheet transport unit 20 described later. The secondary transfer roller 16 is disposed in pressure contact with the intermediate transfer belt 15 to form a transfer nip.

  The sheet conveyance unit 20 conveys the sheet P fed from the sheet feeding unit 21 along the conveyance path. In the sheet feeding unit 21, the sheets P are stacked on a sheet tray, and the sheets P stacked on the sheet tray are taken in by the sheet feeding unit 22 and are sent out to the conveyance path. The conveyance path is provided with a plurality of sheet conveyance means for conveying the sheet P. Each conveyance means is constituted by a pair of rollers pressed against each other, and at least one roller is rotationally driven through an electric motor which is a drive means. In addition, the conveyance means can employ | adopt widely the structure which consists of a pair of rotation members like a combination of belts, a combination of a belt, and a roller besides comprising by a pair of rollers.

  The fixing device 30 is a device that performs a fixing process on the sheet P on which the image is transferred. The fixing device 30 includes, for example, a pair of fixing rollers that are in pressure contact with each other to form a fixing nip, and a heater that heats one or both of the fixing rollers. The fixing device 30 fixes the transferred image to the sheet P through the action of the pressure of the pair of fixing rollers and the heat of the fixing rollers. The sheet P subjected to the fixing process by the fixing device 30 is discharged to the outside of the apparatus by the sheet discharge roller 23.

  When the image formation is also performed on the back surface of the sheet P, the sheet P on which the image formation on the front surface of the sheet P is completed is conveyed by the switching gate 24 to the sheet refeeding conveyance path. In the sheet re-feeding transport path, the trailing edge of the transported sheet P is nipped by the reversing roller, and then, the sheet P is reversed by reverse feeding. The sheet P whose front and back sides are reversed is conveyed by a plurality of conveyance rollers, and is joined to the conveyance path on the upstream side of the transfer position in order to form an image on the other side.

  The operation panel 45 is a touch panel type input unit capable of inputting information in accordance with information displayed on a display (not shown). The user can set information related to the sheet P, specifically, the density or magnification of the image, a sheet tray serving as a sheet feed source, and the like through the operation on the operation panel 45. The control panel 45 also functions as a display unit for displaying various information to the user via the control panel 45 by being controlled.

  The image reading device 3 is disposed downstream of the image forming device 2. The image reading device 3 is provided with a sheet conveyance unit 50. Further, in the image reading device 3, a scanner 60a, a scanner 60b, a spectrocolorimeter 70, and the like are provided from the upstream side to the downstream side. The sheet conveyance unit 50 has a conveyance path for conveying the sheet P fed from the image forming apparatus 2 and discharging the sheet P to the outside of the apparatus. A backing 80a is provided at a position facing the scanner 60a. A backing 80b is provided at a position facing the scanner 60b. A backing 80 c is provided at a position facing the spectrocolorimeter 70. When one of the backings 80 a to 80 c is not particularly limited, the backing 80 is referred to.

  An upstream conveyance roller 91a is provided on the upstream side of the scanner 60a. The downstream side conveyance roller 92a is provided downstream of the scanner 60a. An upstream conveyance roller 91 b is provided on the upstream side of the scanner 60 b. On the downstream side of the scanner 60b, a downstream side conveyance roller 92b is provided. An upstream conveyance roller 91 c is provided on the upstream side of the spectrocolorimeter 70. On the downstream side of the spectrocolorimeter 70, a downstream side conveyance roller 92c is provided.

  When one of the upstream side conveyance rollers 91 a to 91 c is not particularly limited, it is referred to as an upstream side conveyance roller 91. Moreover, in the case where one of the downstream side conveyance rollers 92 a to 92 c is not particularly limited, it is referred to as a downstream side conveyance roller 92.

  For example, when the sheet P supplied from the image forming apparatus 2 is received, the image reader 3 detects an image formed on the sheet P. The scanners 60a and 60b are disposed so as to face the sheet P conveyed on the conveyance path, and read an image formed on the sheet P.

  Specifically, the scanner 60 a is for reading the back of the sheet P, and is used to check, for example, the misalignment of the front and back of the image printed on the sheet P, and the presence or absence of an unexpected image. The scanner 60 b is for reading the surface of the sheet P, and is used for an operation of reading an image printed on the sheet P, specifically, the patch 201 or the like. When the scanner 60a and the scanner 60b are generically referred to as the scanner 60.

  Next, the image forming apparatus 2 and the image reading apparatus 3 will be described including the functional configuration with reference to FIG. FIG. 2 is a diagram showing an example of a functional configuration of the image forming system according to the present embodiment. The functional configuration of the image forming system can be realized using a microcomputer mainly configured of a CPU, a ROM, a RAM, and an I / O interface.

  First, the scanner 60 and the spectrocolorimeter 70 will be described. The scanner 60 is provided on the upstream side of the spectrocolorimeter 70, and the light source 101 for emitting light to the sheet P passing the reading position, and a plurality of imaging elements for photoelectric conversion for each pixel are one-dimensional in the sheet width direction. It is mainly composed of line image sensors arranged side by side. The reading range of the scanner 60 is set to cover the maximum width of the sheet P that can be supplied from the image forming apparatus 2. The scanner 60 repeatedly performs an operation of reading an image of one line extending in the sheet width direction in accordance with the conveyance operation of the sheet P passing the reading position, thereby forming an image formed on the sheet P into a two-dimensional image. Read as The read image is generated as a read of the image.

  That is, the scanner 60 has a line image sensor that reads the sheet P along the width direction of the sheet P, and reads the entire width of the sheet P in the conveyance direction of the sheet P as one line. Can be acquired. When the spectrocolorimeter 70 and the scanner 60 are collectively referred to as the reading device 55, the image reading device 3 reads the sheet P by the reading device 55, and the result is fed back to the image forming device 2. .

  That is, the image reading device 3 is associated with the reading result of the scanner 60 based on the reading result of the spectrocolorimeter 70, and the image forming device 2 is a reading result of the sheet P by the image reading device 3. Based on this, a color profile of the color of the image formed on the sheet P is created.

  Here, the imaging device is specifically a CCD (Charge Coupled Device). The CCD is an optical sensor that reads an image on the sheet P at the reading position, and functions as a color line sensor capable of reading the entire width in the width direction of the sheet P by being arranged in a line is there.

  Specifically, when the reading operation is actually performed, an optical system (not shown) and a light source 101 of a light emitting diode (LED) that illuminates the reading position operate in cooperation with each other in addition to the imaging device. The optical system is for guiding an image at a reading position to a CCD, and includes a plurality of mirrors and a plurality of lenses. The line image sensor described above can be realized by the CCD line sensor 103.

  The spectrocolorimeter 70 is disposed to face the sheet P conveyed on the conveyance path, and is disposed downstream of the scanner 60. The spectrocolorimeter 70 measures a patch 201 or the like described later.

  Specifically, the spectral colorimeter 70 irradiates a visible light source from the light source 105 toward the patch 201 etc., and the spectral imaging unit 107 acquires the spectral spectrum of the reflected light of the visible light source, and a predetermined color system Perform operations on Thus, the color tone of the patch 201 or the like can be derived.

  The colorimetric range of the spectrocolorimeter 70, that is, the viewing angle, is set smaller than the reading range of the scanner 60 and smaller than the width of the patch 201 along the paper width direction. Specifically, the lens unit for acquiring the reflected light of the patch 201 is, for example, about 4 mm. In this case, the size of the patch 300 of 4 mm + α is required for one spectrocolorimeter 70 in the paper width direction.

  As described above, since the spectrocolorimeter 70 performs colorimetry while limiting to a certain range of viewing angles, color information can be reproduced with higher accuracy than the scanner 60. For this reason, only when the sheet P passes through the transport path once, the colorimetry is performed only for one patch 201 row.

  As shown in FIG. 1, the image forming apparatus 2 is provided on the upstream side of the image reading apparatus 3. The image reading apparatus 3 is operated by either the in-line method or the off-line method.

  The in-line type is configured to directly feed an image-formed sheet P discharged from the image forming apparatus 2 to the image reading apparatus 3. On the other hand, in the off-line method, the image forming sheet 2 discharged from the image forming device 2 is not directly fed to the image reading device 3, and the image forming device 2 and the image reading device 3 are not Are independently configured schemes. Here, although the following explanation is given on the premise of the in-line method, it may be the off-line method.

  Next, the switching control unit 111 and the clock unit 113 configured as the functional configuration of the image reading device 3 will be described. In addition, although the reader 55 demonstrated below assumes the spectrocolorimeter 70, the reader 55 may be the scanner 60. FIG.

  The backing 80 described above is disposed so as to face the reading device 55, and an opposing surface facing the reading device 55 is formed. The switching control unit 111 performs control to switch the color of the facing surface formed on the backing 80. The clock unit 113 measures a preset time after the completion of reading of the patch 201_n and the like at the rearmost end, and transmits a clocking result to the switching control unit 111.

  Specifically, the switching control unit 111 switches the color of the surface facing the reading device 55 formed on the backing 80 to either black or white based on the reading device 55 reading the sheet P. is there. The switching control unit 111 switches the color of the facing surface formed on the backing 80 to black when the reading device 55 reads one of the leading end and the trailing end of the sheet P.

  More specifically, the switching control unit 111 causes the reading device 55 to read the leading patch 201, that is, the facing surface formed on the backing 80 before the reading device 55 starts reading the patch 201_1. The color of is switched from black to white. The switching control unit 111 switches the color of the facing surface formed on the backing 80 from white to black until the reading operation of the rear end portion of the sheet P by the reading device 55 is started. The switching control unit 111 switches the color of the facing surface formed on the backing 80 to white when the reading device 55 reads the patch 201.

  Next, the formation range of the patch 201 formed on the sheet P will be described. The formation range of the patch 201 is the position of the nip for suppressing the slack of the paper P within the allowable range, the switching time until the switching control unit 111 switches the color of the facing surface formed on the backing 80 to white, and It is determined based on the transport speed to be transported. Further, the formation range of the patch 201 is determined within the transport distance in which the sheet P is transported according to the transport speed of the sheet P while the color of the facing surface formed on the backing 80 is white. is there.

  The nip for suppressing the slack of the sheet P within the allowable range is formed on each of the upstream side conveyance roller 91 on the upstream side of the reading device 55 and the downstream side conveyance roller 92 on the downstream side of the reading device 55 It is. In such a nip, the formation range of the patch 201 is determined within the distance between the upstream nip formed by the upstream conveyance roller 91 and the downstream nip formed by the downstream conveyance roller 92. It is a thing. The shape and size of the patch 201 are determined based on the reading range of the reading device 55 and the transport speed of the sheet P.

  Next, the acquisition unit 121 and the image processing unit 123 configured as the functional configuration of the image forming apparatus 2 will be described. First, the function of forming the patch 201 on the sheet P will be described.

  When forming the patch 201, the image forming apparatus 2 applies the patch within the transport distance for transporting the sheet P according to the transport speed of the sheet P while the color of the facing surface formed on the backing 80 is white. The color of the facing surface formed on the backing 80 and the transport distance of the paper P are considered so that the formation range of 201 can be configured.

  The acquisition unit 121 determines the position of the nip for suppressing the slack of the sheet P within the allowable range, the switching time until the color of the facing surface formed on the backing 80 switches to white, and the transport speed at which the sheet P is transported. To get

  The image processing unit 123 determines the formation range of the patch 201 formed on the sheet P based on the position of the nip, the switching time, and the transport speed acquired by the acquisition unit 121, and the image forming unit based on the determination result. It controls 10Y, 10M, 10C and 10K.

  Specifically, the image processing unit 123 optimizes the image formed on the image forming units 10Y, 10M, 10C, and 10K based on the reading result of the scanner 60 and the color measurement result of the spectrocolorimeter 70. It is a thing. Specifically, the image optimization processing includes front and back position adjustment, density adjustment, and tint adjustment of an image to be printed on the sheet P.

  The image processing unit 123 forms the patch 201 when, for example, a color adjustment mode command is received. The color adjustment mode guarantees the absolute value of the color by measuring the color of the patch 201 It is Further, in the color adjustment mode, when an image position instruction is included in the color adjustment mode command, an image position adjustment mark for adjusting the image position is formed, and the image position adjustment is performed. It will be.

  Next, the patch 201 formed on the sheet P will be described with reference to FIGS. FIG. 3 is a view showing the correspondence between the lightness L * and the measurement position when the lightness difference between the adjacent patches 201 is small. FIG. 4 is a diagram showing the correspondence between the lightness L * and the measurement position when the lightness difference between the adjacent patches 201 is large. In FIGS. 3 and 4, a solid circle is a cutout OK region, and a broken circle is a region straddling the patch 201, which is a cutout NG region.

  In the case of reading the patch 201 without stopping the conveyance of the sheet P in the in-line, that is, when performing the flow reading of the patch 201 in the inline, the patch 201 is usually determined after measuring the patch 201 on the sheet P to be conveyed. Measurement of the color of. Therefore, some timing is needed for timing detection for measuring the patch 201. In order to determine such a trigger, it is common to use a reflective sensor that detects the leading edge of the sheet P or a dedicated sensor that measures a trigger patch.

  In such a configuration, since a dedicated sensor is provided, the number of parts increases and the cost also increases. Furthermore, since the position of the sensor changes depending on the mounting accuracy, the detection accuracy of the sensor may be lowered, and the patch 201 may be straddled.

  In order to compensate for the decrease in detection accuracy of the sensor, there is a method of enlarging the patch 201 in the sub-scanning direction. In this case, the number of patches that can be arranged on one sheet of paper P decreases, the number of sheets necessary for measurement increases, and the burden on the user increases. For example, depending on the contents of adjustment, when the number of patches is large, it will be 1000 patches or more.

  Specifically, as shown in FIG. 3, in the case of control in which the entire area is measured without the patch 201 and only the necessary part is cut out, the lightness difference between the adjacent patches 201 is small, and the judgment of the cutout OK area is difficult. Therefore, as shown in FIG. 4, by arranging the patches 201 so that colors having small lightness differences are not adjacent, the lightness differences of the adjacent patches 201 are large, and it is necessary to clarify the clipping OK area. There will be a restriction on the arrangement of 201. The arrangement configuration of the patch 201 shown in FIG. 4 is not realistic because the control method becomes complicated and the number of development steps becomes large.

  Therefore, there is a method of detecting the leading edge of the sheet P based on a change in color when the sheet P is conveyed to the backing 80. In this case, since the spectrocolorimeter 70 also serves as a sensor for detecting the leading edge of the sheet P, the error of the measurement position is reduced, and the measurement accuracy is improved. FIG. 5 is a diagram showing the color of the surface facing the spectrocolorimeter 70 formed on the backing 80 when the end of the sheet P is read. FIG. 6 is a diagram showing the color of the surface facing the spectrocolorimeter 70 formed on the backing 80 when the patch 201 formed on the sheet P is read. As shown in FIG. 5, the color of the surface facing the spectrocolorimeter 70 formed on the backing 80 is a dark color, for example, black, in order to increase the difference from the paper white of the paper P. In this case, in order to detect the end portion of the sheet P of the spectrocolorimeter 70, for example, a difference may be calculated by comparing the lightness L * of the spectral reflectance with the facing surface formed on the backing 80.

  However, in order for the spectrocolorimeter 70 to measure the absolute value of the color, the color of the facing surface formed on the backing 80 needs to be white which does not affect the measurement. In addition, in order to obtain certification by a color certification authority such as JapanColor, FORGA, or G7, the color of the facing surface formed on the backing 80 is required to be white. Therefore, as shown in FIG. 6, the color of the facing surface formed on the backing 80 may be white, and the color may be measured.

  However, as shown in FIG. 6, when the color of the facing surface formed on the backing 80 is white, the lightness difference with the paper white at the front end of the paper P is small. The error will be large. Therefore, when the leading end of the sheet P is read, a color that is easily determined to be paper white, for example, black, is used as the color of the facing surface formed on the backing 80 and is formed on the backing 80 by a signal obtained by reading the leading end of the sheet P. Control may be made to switch the color of the facing surface to white.

  When the patch 201 is continuously measured, the color of the opposing surface formed on the backing 80 is black until the leading edge of the next sheet P reaches the measurement position when the trailing edge of the sheet P is detected. It may be controlled to be held. In this way, it is possible to increase the difference in lightness between the front end of the sheet P and the rear end of the sheet P from the color of the facing surface formed on the backing 80. Thus, the end of the sheet P can be detected with high accuracy. Further, when the color of the image formed on the sheet P is measured, if the color of the facing surface formed on the backing 80 is switched to white, the absolute value of the color can be accurately measured, and color authentication can also be taken. it can.

  FIG. 7 is a diagram schematically illustrating the switching timing of the color of the opposite surface to the spectrocolorimeter 70 formed on the backing 80. Since the sheet P tends to curl due to the heat and pressure of the fixing device 30, the patch 201 is not disposed at the leading end of the sheet P and the rear end of the sheet P. Therefore, the color of the facing surface formed on the backing 80 is switched using the margin created by not arranging the patch 201. Further, the switching speed of the color of the facing surface formed on the backing 80 is always constant.

  FIG. 8 is a diagram schematically illustrating the relationship between the switching timing of the color of the surface facing the spectrocolorimeter 70 formed on the backing 80 and the position of the nip. FIG. 9 is a diagram for explaining in stages the relationship between the switching timing of the color of the surface facing the spectrocolorimeter 70 formed on the backing 80 and the position of the nip.

  As shown in FIGS. 8 and 9, in the section X1, the leading edge of the sheet P is detected by the density difference between the color of the facing surface formed on the backing 80 and the color of the paper white on the leading edge side of the sheet P. . Next, in the section X2, the color of the facing surface formed on the backing 80 is switched from black to white by rotating the backing 80. Next, in the section X3, the leading edge of the sheet P is nipped by the downstream conveyance roller 92. That is, the distance by which the sheet P is conveyed to the section X3 is the distance from the leading end of the sheet P to the position of the nip formed on the downstream side conveyance roller 92.

  Next, in the section X4, while the sheet P is being conveyed, the color of the opposite surface formed on the backing 80 is white, and the sheet P is used for each of the downstream conveyance roller 92 and the upstream conveyance roller 91. It is nipped. Next, in the section X5, the color of the facing surface formed on the backing 80 is switched from white to black by rotating the backing 80. Since the position of the patch 201 — n at the rear end is known when writing the patch 201, the color of the opposite surface formed on the backing 80 is controlled to switch to black when the section X5 is exceeded. Next, in the section X6, when the color of the facing surface formed on the backing 80 is black, the trailing edge of the sheet P is detected.

  As described above, first, the formation range of the patch 201 is satisfied that the leading edge of the sheet P is nipped by the downstream conveyance roller 92 and the color of the facing surface formed on the backing 80 is completely switched to white. It becomes. In addition, the formation range of the patch 201 secondly is that the rear end of the sheet P is nipped by the upstream conveyance roller 91. As described above, the patch 201 is not formed at the position where it has passed through the nip, and the patch 201 is formed between the nips, so that the patch 201 is read in the area where the height variation of the sheet P is small. Can. That is, the formation range of the patch 201 is restricted within the distance between the upstream nip and the downstream nip.

  FIG. 10 is a diagram schematically illustrating the switching timing of the color of the surface facing the spectrocolorimeter 70 formed on the backing 80 when the image position adjustment mark is added to the sheet P. As shown in FIG. 10, the image position adjustment mark serves as a reference for adjusting the position of the image formed on the sheet P. The image position adjustment mark is located in the margin between the leading end of the sheet P and the patch 201_1 which is the top patch 201 of the patch 201, or the rear end of the sheet P and the patch at the rear end of the patch 201 It is formed in the margin between the patch 201 and the patch 201_n.

  When reading the image position adjustment mark, after the image position adjustment mark is read, the color of the facing surface formed on the backing 80 is completely switched to white, and the leading edge of the sheet P is nipped by the downstream conveyance roller 92 Is a condition. Note that since the image position adjustment mark has a larger allowable reading accuracy in the height direction than in the case of color, there is no need for the leading edge of the sheet P to be nipped by the downstream conveyance roller 92.

  Next, color adjustment processing and color and image position adjustment processing will be described. FIG. 11 is a flowchart for explaining an operation example of the color adjustment process. FIG. 12 is a flowchart for explaining an operation example of color and image position adjustment processing.

  In step S11, it is determined whether the color adjustment mode is set. If it is the color adjustment mode (YES in step S11), the process proceeds to step S12, and it is determined whether there is an image position adjustment mark. If there is an image position adjustment mark (YES in step S12), the process proceeds to step S13. If the process is executed and there is no image position adjustment mark (NO in step S12), the process proceeds to step S27, and color and image position adjustment process is performed. On the other hand, when the color adjustment mode is not set (NO in step S11), the process waits for an instruction of the color adjustment mode to arrive.

(Color adjustment processing)
(Image forming apparatus 2)
In step S13, the transport speed of the sheet P is determined based on the sheet feed setting. In step S14, the formation range of the patch 201 is obtained. In step S15, the position where the patch 201 is to be formed is determined based on the formation range of the patch 201. In step S16, an operation of printing the patch 201 is started.

(Image reader 3)
In step S17, the color of the facing surface of the backing 80 is switched from white to black. In step S18, the leading end of the sheet P is detected. In step S19, the color of the facing surface of the backing 80 is switched from black to white. In step S20, the patch 201 is read, and in step S21, it is determined whether the reading of the patch 201_n at the end is completed, and when the reading of the patch 201_n at the end is completed (YES in step S21), The process proceeds, and when the reading of the patch 201_n at the end is not completed (NO in step S21), the process returns to step S20, and the patch 201 is read. In step S22, the read result of the patch 201 is transmitted to the image processing unit 123. In step S23, it is determined whether or not a preset time has elapsed. If the preset time has elapsed (YES in step S23), the process proceeds to step S24. In step S24, the color of the facing surface of the backing 80 is switched from white to black.

  In step S25, it is determined whether or not the sheet P on which the patch 201 is printed is conveyed, and if the sheet P on which the patch 201 is printed is not conveyed (NO in step S25), the process proceeds to step S26, and the patch 201 is printed. If the sheet P is conveyed (YES in step S25), the process returns to step S18, and the operation of detecting the leading edge of the sheet P is performed again. In step S26, the normal print process is a process in which an image other than the patch 201 and the image position adjustment mark is printed on the sheet P.

(Color and image position adjustment process)
(Image forming apparatus 2)
In step S41, the transport speed of the sheet P is determined based on the sheet feed setting. In step S42, the formation range of the image position adjustment mark is obtained. In step S43, the formation range of the patch 201 is obtained. In step S44, based on the formation range of the patch 201 and the formation range of the image alignment mark, positions to form the patch 201 and the image alignment mark are determined. In step S45, an operation of printing the patch 201 and the mark for image position adjustment is started.

(Image reader 3)
In step S46, the color of the facing surface of the backing 80 is switched from white to black. In step S47, the leading end of the sheet P is detected. In step S48, the image position adjustment mark on the tip side is read. In step S49, the color of the facing surface of the backing 80 is switched from black to white. In step S50, the patch 201 is read, and in step S51, it is determined whether the reading of the patch 201_n at the end is completed, and when the reading of the patch 201_n at the end is completed (YES in step S51), If the process proceeds to step S51 (NO at step S51), the process returns to step S50, and the patch 201 is read. In step S52, it is determined whether or not a preset time has elapsed. If the preset time has elapsed (YES in step S52), the process proceeds to step S53.

  In step S53, the color of the facing surface of the backing 80 is switched from white to black. In step S54, the image position adjustment mark on the rear end side is read. In step S55, the read results of the patch 201 and the image position adjustment mark are transmitted to the image processing unit 123. In step S56, it is determined whether or not the sheet P on which the patch 201 is printed is conveyed, and the sheet P on which the patch 201 is printed is not conveyed (NO in step S56), the normal printing process of step S26 in FIG. After shifting, when the sheet P on which the patch 201 is printed is conveyed (YES in step S56), the process returns to step S47, and the operation of detecting the leading edge of the sheet P is executed again.

  After the color and image position adjustment processing is completed, the process returns to step S26 in FIG. 11, and the normal print processing is performed.

  From the above description, in the image reading device 3, the formation range of the patch 201 formed on the sheet P is determined based on the position of the nip that suppresses the slack of the sheet P within the allowable range. Therefore, due to the positional relationship between the sheet P and the nip, the slack of the sheet P is suppressed within the allowable range in the formation range of the patch 201. That is, the patch 201 is formed in an area where the height variation of the sheet P is small. Therefore, since the color of the patch 201 is measured in the area where the height variation of the paper P is small, the light quantity reflected is largely changed as the height of the paper P changes, and the density of the color to be measured is large. You can avoid changing situations. As a result, it is under the measurement environment which can secure the color reading accuracy with high accuracy.

  In addition, the color of the surface facing the reading device 55 formed on the backing 80 can be switched to either black or white. Therefore, when the color is measured, if the color of the facing surface formed on the backing 80 is switched to white, the absolute value of the color can be measured accurately. Therefore, the formation range of the patch 201 formed on the sheet P is determined based on the switching time until the color of the facing surface formed on the backing 80 is switched to white and the transport speed at which the sheet P is transported. Thus, when the patch 201 is measured, the color of the facing surface formed on the backing 80 can be white. Therefore, the absolute value of color can be measured accurately.

  In other words, it is possible to accurately measure the absolute value of color under the measurement environment where color reading accuracy can be ensured with high accuracy. Therefore, highly accurate image correction can be performed.

  Further, since the nip is formed on the upstream side conveyance roller 91 upstream of the reading device 55 and the downstream side conveyance roller 92 downstream of the reading device 55, the reading device 55 and the sheet P And the distance between the sheet P and the backing 80 can be kept constant. Therefore, when the sheet P passes through the reading device 55, the sheet P does not flutter. Therefore, the height variation of the sheet P can be suppressed. Thus, the reading device 55 can read the sheet P in an area where the height variation of the sheet P is small.

  Further, since the formation range of the patch 201 is determined within the distance between the upstream nip formed by the upstream conveyance roller 91 and the downstream nip formed by the downstream conveyance roller 92 in the nip. The patch 201 is formed at a position where the sheet P does not flicker. As a result, the reading device 55 can read the patch 201 in an area where the height variation of the sheet P is small.

  Further, since the shape and size of the patch 201 are determined based on the reading range of the reading device 55 and the transport speed of the sheet P, the printable range of the sheet P can be effectively used. Thereby, the number of sheets used can be reduced.

  In addition, when the reading device 55 reads any of the leading end and the trailing end of the sheet P, the color of the facing surface formed on the backing 80 is switched to black, so the leading end and the trailing end of the sheet P The difference between the density of each color of and the density of the color of the opposing surface formed on the backing 80 can be increased. Therefore, the end of the sheet P can be detected with high accuracy. Therefore, the timing for reading the sheet P can be accurately determined, so that the color measurement timing can be accurately determined. Thereby, the reading device 44 can measure the patch 201 at the correct position.

  Further, the mark for image position adjustment is in the margin between the leading end of the sheet P and the top patch 201_1 of the patch 201 or the back end of the sheet P and the patch 201_n of the back end of the patch 201. And the color of the opposite surface formed on the backing 80 is switched from black to white until the reading operation of the leading patch 201_1 by the reading device 55 is started. The color of the facing surface formed on the backing 80 is switched from white to black until the reading operation of the rear end of the sheet P by the reading device 55 is started. Thus, the color of the facing surface formed on the backing 80 can be switched at an appropriate timing. Thereby, the image position adjustment mark and the patch 201 can be read accurately.

  Further, when the reading device 55 reads the patch 201, the color of the facing surface formed on the backing 80 is switched to white, so that the color of the facing surface formed on the backing 80 is white. Then, the patch 201 will be read. This makes it possible to accurately measure the absolute value of the color.

  Further, while the color of the facing surface formed on the backing 80 is white, the formation range of the patch 201 is determined within the transport distance in which the sheet P is transported according to the transport speed of the sheet P. Therefore, the formation range of the patch 201 is determined within the necessary minimum range. Therefore, wasteful use of the paper P is avoided. Thereby, the cost of the sheet P and the color measurement time of the patch 201 can be reduced.

  The reading device 55 is a spectral colorimeter 70 or a scanner 60. The scanner 60 is provided on the upstream side of the spectral colorimeter 70 and reads the sheet P along the width direction of the sheet P. Since the reading result of the scanner 60 is corrected based on the reading result of the colorimeter 70, the image of the full width of the sheet P can be corrected. Thereby, the time required for the adjustment operation of the color of the image formed on the sheet P can be shortened.

  The image forming apparatus 2 is provided on the upstream side of the image reading apparatus 3, and the image forming apparatus 2 sets the position of the nip for suppressing the slack of the sheet P within the allowable range and the color of the opposite surface formed on the backing 80 The formation range of the patch 201 is determined on the basis of the switching time until switching to and the conveyance speed at which the sheet P is conveyed. Therefore, the image forming apparatus 2 can make the image reading apparatus 3 accurately measure the absolute value of the color under the measurement environment where the color reading accuracy can be secured with high accuracy. This makes it possible to perform highly accurate image correction.

  Since the image forming apparatus 2 creates a color profile of the color of the image to be formed on the sheet P based on the reading result of the sheet P by the image reading device 3, the color of the image can be adjusted at an early stage. Therefore, the adjustment work of the color of the image formed on the paper P can be made efficient.

  The image forming system including the image reading apparatus 3 described above and the image forming apparatus 2 described above can perform image correction with high accuracy. Thus, an image comparable to offset printing can be formed on the sheet P.

  As described above, according to the image reading device 3 according to the present embodiment, the reading device 55 for reading the sheet P and the facing surface facing the reading device 55 and having the facing surface facing the reading device 55 are formed. A backing 80, and a switching control unit 111 that switches the color of the surface facing the reading device 55 formed on the backing 80 to either black or white based on the reading device 55 reading the sheet P; The formation range of the patch 201 formed on the sheet P is the position of the nip that suppresses the slack of the sheet P within the allowable range, the switching time until the switching control unit 111 switches the color of the facing surface to white, and the sheet P It is characterized in that it is determined based on the transport speed to be transported. Thereby, highly accurate image correction can be performed.

  In addition, the nip is formed on each of the upstream side conveyance roller 91 on the upstream side of the reading device 55 and the downstream side conveyance roller 92 on the downstream side of the reading device 55. Thus, the reading device 55 can read the sheet P in an area where the height variation of the sheet P is small.

  Further, the formation range of the patch 201 is determined within the distance between the upstream nip formed by the upstream conveyance roller 91 and the downstream nip formed by the downstream conveyance roller 92 among the nips. It is. As a result, the reading device 55 can read the patch 201 in an area where the height variation of the sheet P is small.

  Further, the shape and size of the patch 201 are determined based on the reading range of the reading device 55 and the transport speed. Thereby, the number of sheets used can be reduced.

  Further, when the reading device 55 reads one of the leading end and the trailing end of the sheet P, the switching control unit 111 switches the color of the facing surface to black. Thereby, the reading device 44 can measure the patch 201 at the correct position.

  Further, an image position adjustment mark serving as a reference for adjusting the position of the image formed on the sheet P is formed. The image position adjustment mark is formed by the leading end of the sheet P and the first patch 201_1 of the patches 201. The switching controller 111 is formed in the space between the rear end of the sheet P and the rear end patch 201_n of the patch 201, and the switching control unit 111 controls the leading patch of the reading device 55. The color of the opposite surface is switched from black to white until the reading operation of 201_1 is started, and the color of the opposite surface is changed until the reading operation of the rear end of the sheet P by the reading device 55 is started. It switches from white to black. Thereby, the image position adjustment mark and the patch 201 can be read accurately.

  Further, the switching control unit 111 switches the color of the facing surface to white when the reading device 55 reads the patch 201. This makes it possible to accurately measure the absolute value of the color.

  Further, while the color of the facing surface is white, the formation range of the patch 201 is determined within the transport distance in which the sheet P is transported according to the transport speed. As a result, the number of sheets used for adjustment can be reduced, and cost reduction and color measurement time of the patch 201 can be reduced.

  The reading device 55 is a spectrocolorimeter 70 or a scanner 60. The scanner 60 is provided on the upstream side of the spectrocolorimeter 70, and is a CCD that reads the sheet P along the width direction of the sheet P. The line sensor 103 is provided, and the reading result of the scanner 60 is corrected based on the reading result of the spectrocolorimeter 70. Thereby, the time required for the adjustment operation of the color of the image formed on the sheet P can be shortened.

  The image forming apparatus 2 provided on the upstream side of the image reading device 3 is an nip obtained by the acquiring unit 121 and the acquiring unit 121 that acquires the position of the nip, the switching time, and the conveyance speed. And an image processing unit 123 that determines the formation range of the patch 201 formed on the sheet P based on the position, the switching time, and the transport speed. This makes it possible to perform highly accurate image correction.

  Further, the image processing unit 123 creates a color profile of the color of the image to be formed on the sheet P based on the reading result of the sheet P by the image reading device 3. Thereby, the adjustment work of the color of the image formed on the paper P can be made efficient.

  The image forming system also includes an image reading device 3 and an image forming device 2. Thus, an image comparable to offset printing can be formed on the sheet P.

  As mentioned above, although the image processing device concerning the present invention was explained based on an embodiment, the present invention is not limited to this, You may add a change in the range which does not deviate from the meaning of the present invention.

  For example, although an example in which two scanners 60 are provided has been described, the present invention is not limited to this, and only one scanner 60 may be provided. In this case, by providing a transport path for reversing the sheet P, the front and back of the sheet P may be read by one scanner 60. Further, three or more scanners 60 may be provided.

  In addition, in the present embodiment, an example of switching the color of the surface facing the reading device 55 formed on the backing 80 to either black or white has been described, but the present invention is not limited thereto. It may be configured to switch to any of the colors.

  Moreover, although the example which changes the color of the opposing surface with the reader 55 formed in the backing 80 by rotating the backing 80 was demonstrated, not only this but the backing 80 is made into a flat plate and it is black on a flat plate And white may be formed. When the backing 80 is a flat plate, the color of the facing surface formed on the backing 80 may be switched to either black or white by moving the flat plate in parallel.

  Further, although an example in which the imaging device is a CCD has been described, the present invention is not limited to this, and the imaging device may be a CMOS.

Reference Signs List 1 sheet feeding device 2 image forming device 3 image reading device 4 sheet discharging device 10Y, 10M, 10C, 10K image forming unit 11Y, 11M, 11C, 11K photosensitive drum 15 intermediate transfer belt 16 secondary transfer roller 20, 50 sheet conveyance Section 21 sheet feeding unit 22 sheet feeding section 23 sheet discharge roller 24 switching gate 30 fixing device 45 operation panel 55 reader 60, 60a, 60b scanner 70 spectral colorimeter 80, 80a, 80b, 80c backing 101, 105 light source 103 CCD line sensor 107 Spectroscopic imaging unit 91, 91a to 91c Upstream conveyance roller 92, 92a to 92c Downstream conveyance roller 111 Switching control unit 113 Timing unit 121 Acquisition unit 123 Image processing unit 201, 201_1 to 201_n Patch SC Document reading device P Paper

  The present invention relates to an image reading apparatus and an image forming system.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide an image reading apparatus and an image capable of shortening the time required for adjusting the color of an image formed on a sheet. It is in providing a forming system.

  In order to achieve the above object, an image reading apparatus according to the present invention includes a transport unit for transporting a sheet, a scanner for reading an image of the sheet transported by the transport unit, and a transport direction by the transport unit. A colorimeter disposed downstream of the scanner and measuring the image of the sheet being conveyed by the conveyance unit within a range narrower than the reading range of the scanner; and the reading result by the scanner is It is characterized in that it is corrected based on the color measurement result by the colorimeter.

  According to this image reading apparatus, it is possible to shorten the time required for adjusting the color of the image formed on the sheet.

  In the image reading apparatus according to the present invention, preferably, the scanner includes a line image sensor in which a plurality of imaging elements are arranged in the width direction of the sheet.

  In the image reading apparatus according to the present invention, preferably, a reading range of the scanner is set to cover a maximum width of the sheet conveyed by the conveyance unit.

  Further, in the image reading device according to the present invention, it is preferable to provide a backing at a position facing the scanner.

  In the image reading apparatus according to the present invention, preferably, a backing is provided at a position facing the colorimeter.

  Further, in the image reading apparatus according to the present invention, it is preferable to provide a conveyance roller upstream and downstream of the scanner.

  Further, in the image reading apparatus according to the present invention, it is preferable to provide a conveyance roller upstream and downstream of the colorimeter.

  In the image reading apparatus according to the present invention, at least front and back position adjustment, density adjustment, or color adjustment of an image to be printed on the sheet is included based on the reading result of the scanner and the colorimetric result of the colorimeter. It is preferable to carry out an optimization process.

  In the image reading apparatus according to the present invention, preferably, the scanner includes a first scanner that reads the back surface of the sheet, and a second scanner that reads the surface of the sheet.

  Further, in the image reading apparatus according to the present invention, it is preferable that the colorimeter be disposed so as to be able to measure an image on the same surface as the surface of the sheet read by the adjacent scanner.

  In the image reading apparatus according to the present invention, a reversing path for reversing the sheet is provided downstream of the scanner, and after the image on one side of the sheet is read by the scanner, the sheet is reversed in the reversing path Preferably, the scanner again reads the image on the other side of the sheet.

Further, to achieve the above object, an image forming apparatus for forming an image on a sheet, a transport unit for transporting the sheet supplied from the image forming apparatus, and an image of the sheet transported by the transport unit A scanner for reading, and colorimetry for measuring an image of the sheet conveyed by the conveyance unit within a range narrower than the reading range of the scanner with respect to the conveyance direction of the conveyance unit and disposed in the downstream side of the scanner And the reading result by the scanner is corrected based on the color measurement result by the colorimeter.
Further, in the image forming system according to the present invention, it is preferable that the image forming apparatus includes a heat fixing device for thermally fixing the image on the sheet.

  According to the present invention, it is possible to shorten the time required for the adjustment of the color of the image formed on the sheet.

Claims (12)

A reading device for reading paper,
A backing disposed opposite to the reading device and having an opposing surface facing the reading device;
A switching control unit configured to switch the color of the surface facing the reading device formed on the backing to either black or white based on the reading device reading the sheet;
Equipped with
The formation range of the patch formed on the sheet is the position of the nip for suppressing the slack of the sheet within the allowable range, the switching time until the switching control unit switches the color of the facing surface to white, and the sheet An image reading apparatus characterized in that it is determined based on a conveyance speed to be conveyed.   The image according to claim 1, wherein the nip is formed on each of an upstream conveyance roller upstream of the reading device and a downstream conveyance roller downstream of the reading device. Reader.   In the nip, the formation range of the patch is determined within the distance between the upstream nip formed by the upstream conveyance roller and the downstream nip formed by the downstream conveyance roller. The image reading apparatus according to claim 2, characterized in that   The image reading apparatus according to any one of claims 1 to 3, wherein the shape and size of the patch are determined based on the reading range of the reading apparatus and the transport speed.   The switching control unit switches the color of the facing surface to black when the reading device reads one of the leading end and the trailing end of the sheet. The image reading device described in. An image position adjustment mark is formed which serves as a reference for adjusting the position of the image formed on the sheet;
The image position adjustment mark may be a margin between the leading end of the sheet and the first patch of the patch, or a trailing end of the sheet and the patch of the trailing end of the patch. Formed in the space between the
The switching control unit is configured to switch the color of the opposite surface from black to white before the reading operation of the leading patch by the reading device is started, and the switching control unit controls the rear end portion of the sheet by the reading device. 6. The image reading apparatus according to claim 5, wherein the color of the facing surface is switched from white to black until the reading operation is started.   The image reading apparatus according to any one of claims 1 to 6, wherein the switching control unit switches the color of the facing surface to white when the reading apparatus reads the patch.   The patch forming range is determined within the transport distance in which the sheet is transported according to the transport speed while the color of the facing surface is white. The image reading device described in. The reading device is a spectrocolorimeter or a scanner,
The scanner is provided on the upstream side of the spectral colorimeter, and has a CCD line sensor that reads the sheet along the width direction of the sheet.
The image reading apparatus according to any one of claims 1 to 8, wherein the reading result of the scanner is corrected based on the reading result of the spectrocolorimeter. An image forming apparatus provided on the upstream side of the image reading apparatus according to any one of claims 1 to 9,
An acquisition unit that acquires the position of the nip, the switching time, and the conveyance speed;
An image processing unit that determines a formation range of a patch to be formed on the sheet based on the position of the nip, the switching time, and the transport speed acquired by the acquisition unit;
An image forming apparatus comprising:   11. The image forming apparatus according to claim 10, wherein the image processing unit is configured to create a color profile of a color of an image to be formed on the sheet based on a reading result of the sheet by the image reading apparatus. apparatus. The image reading apparatus according to any one of claims 1 to 9.
An acquisition unit provided on the upstream side of the image reading apparatus and acquiring the position of the nip, the switching time, and the conveyance speed, and the position of the nip acquired by the acquisition unit An image processing apparatus having an image processing unit that determines a formation range of a patch to be formed on the sheet based on time and the transport speed;
An image forming system comprising:

Images