Image forming apparatus and image reading apparatus

Abstract

To stabilize the position of an opposite member provided opposite to a reading unit to prevent a reduction in reading accuracy of the reading unit.SOLUTION: An image forming apparatus 100 has a first conveyance guide 135a and a second conveyance guide 135b that form a conveyance path in which a sheet on which an image is formed by an image forming section 102 is conveyed. The image forming apparatus 100 further has a color sensor 200 that reads an image on the sheet through a conveyance guide hole 602 formed in the first conveyance guide 135a, and an opposite roller 601 that is opposite to the color sensor 200. The opposite roller 601 is held by a swing arm 603 movably between a contact position and a separation position. The swing arm 603 includes a contact part 603a in contact with the first conveyance guide 135a when the opposite roller 601 is located at the contact position.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus that forms an image on a sheet and a reading apparatus that reads the image on the sheet. [Background technology]

[0002] In recent years, image forming devices used in on-demand printing have been required to maintain high image quality. Indicators of image quality include graininess, in-plane uniformity, character quality, color reproducibility (including color stability), and geometric characteristics (including front-to-back registration). Furthermore, the longer the time required to adjust and check image quality, the lower the availability of the image forming device. Therefore, there is a growing demand for image forming devices with the ability to output test images (patch images) and automatically adjust image formation conditions.

[0003] Patent Document 1 describes an image forming apparatus that automatically corrects image formation conditions by reading a patch image formed on a sheet with a reading unit. Patent Document 2 also describes that an opposing member provided in a position opposing the reading unit moves toward and away from the reading unit in order to align the position of the sheet with the focal position of the reading unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-054324 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-131205 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the opposing member moves to a position close to the reading unit, the position of the opposing member may not be stable. If the position of the opposing member is not stable when the reading unit reads the patch image on the sheet, the distance between the reading unit and the sheet fluctuates, resulting in a problem of reduced reading accuracy.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to stabilize the position of the opposing member and prevent a decrease in the reading accuracy of the reading unit. [Means for solving the problem]

[0007] One aspect of the present invention is an image forming apparatus comprising: an image forming unit that forms an image on a sheet; a first transport guide that has an opening and forms a transport path along which a sheet with an image formed by the image forming unit is transported; a second transport guide that is positioned opposite the first transport guide and forms the transport path together with the first transport guide; a reading unit that reads an image on a sheet transported along the transport path through the opening; an opposing member that faces the reading unit at the reading position of the reading unit; and a holding member that holds the opposing member movably between a first position facing the reading unit and a second position that is further away from the reading unit than the first position, wherein the holding member includes an abutting portion that abuts against the first transport guide when the opposing member is positioned at the first position. [Effects of the Invention]

[0008] According to the present invention, it is possible to stabilize the position of the opposing member and suppress a decrease in the reading accuracy of the reading unit. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. [Figure 2] Schematic diagram of a color sensor. [Figure 3] FIG. 2 is a block diagram showing a control configuration of the image forming apparatus. [Figure 4]A diagram showing an ICC profile. [Figure 5] A schematic diagram of a color management environment. [Figure 6] (a) is a cross-sectional view of the opposing roller and the color sensor when the opposing roller is in the separation position, (b) is a cross-sectional view of the opposing roller and the color sensor when the opposing roller is in the abutment position, and (c) is an enlarged view of the opening when the opposing roller is in the abutment position. [Figure 7] 1A is a side view of the opposing roller support part when the opposing roller is in the separation position, and FIG. 1B is a side view of the opposing roller support part when the opposing roller is in the contact position. [Figure 8] FIG. [Figure 9] (a) is a cross-sectional view of the front swing arm, and (b) is a cross-sectional view of the rear swing arm. [Figure 10] 1A is a diagram showing the roller separating cam when the opposing roller is in the separated position, and FIG. 1B is a diagram showing the roller separating cam when the opposing roller is in the abutting position. [Figure 11] FIG. [Figure 12] FIG. 4 is a perspective view of a drive transmission mechanism for a roller separating cam and an opposing roller. [Figure 13] FIG. 4 is a cross-sectional view showing a driving unit for the opposing roller. [Figure 14] 10 is a flowchart showing control in a color measurement job. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described by way of example with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the present embodiments may be changed as appropriate depending on the configuration of the device to which the present invention is applied and various conditions, and the scope of the present invention is not limited to the following embodiments.

[0011] <Image forming device> First, an image forming apparatus 100 according to this embodiment will be described. Fig. 1 is a cross-sectional view showing the structure of image forming apparatus 100. In this embodiment, the position when a user operates operation unit 180 of image forming apparatus 100 is called the front side of the apparatus, and the opposite side is called the back side of the apparatus. In other words, Fig. 1 is a view of image forming apparatus 100 as seen from the front side.

[0012] As shown in FIG. 1, image forming apparatus 100 includes a housing 101. Housing 101 is equipped with mechanisms constituting image forming unit 102 that forms an image on a sheet P, and a control board housing 104 that houses a printer controller 103 (see FIG. 3 described later) that controls the operation of image forming apparatus 100. Image forming unit 102 of this embodiment includes an optical processing mechanism and a fixing processing mechanism that form an image on a recording material by an electrophotographic process, and a feeding processing mechanism and a conveying processing mechanism that feed and convey sheet P used as the recording material. As the recording material, paper such as plain paper or cardboard, paper with a surface treatment such as coated paper or embossed paper, sheet material such as plastic film or cloth can be used.

[0013] The optical processing mechanism includes stations 120-123 that form toner images of the respective colors of Y (yellow), M (magenta), C (cyan), and K (black), and an intermediate transfer belt 106. In each of the stations 120-123, a primary charger 111 charges the surface of a photosensitive drum 105, which is a drum-shaped image carrier. A laser scanner unit 107 exposes the photosensitive drum 105 based on image data. The laser scanner unit 107 has a laser driver that turns on and off a laser beam emitted from a semiconductor laser 108. The laser beam from the semiconductor laser 108 is directed in the main scanning direction by a rotating polygonal mirror and is guided to the photosensitive drum 105 via a reflecting mirror 109. As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 105.

[0014] The developing unit 112 contains a developer containing toner and supplies charged toner particles to the photosensitive drum 105. The toner particles adhere to the drum surface in accordance with the surface potential distribution, thereby visualizing the electrostatic latent image carried on the photosensitive drum 105 as a toner image. The toner image carried on the photosensitive drum 105 is transferred (primary transfer) to the intermediate transfer belt 106, to which a voltage of the opposite polarity to the normal charging polarity of the toner is applied. When forming a color image, the toner images formed by the four stations 120 to 123 are multi-transferred onto the intermediate transfer belt 106 so that they overlap each other, thereby forming a full-color toner image on the intermediate transfer belt 106.

[0015] The feeding processing mechanism feeds sheets P one by one from a storage 113 inserted retractably into a housing 101 of the image forming apparatus 100 toward a transfer roller 114. A toner image carried on an intermediate transfer belt 106, which is an intermediate transfer body, is transferred (secondary transfer) onto a sheet 1 by the transfer roller 114.

[0016] Around the intermediate transfer belt 106, there are arranged an image formation start position detection sensor 115 for determining the print start position when forming an image, a feed timing sensor 116 for determining the timing of feeding the sheet P, and a density sensor 117. The density sensor 117 measures the density of the patch image carried on the intermediate transfer belt 106. The printer controller 103 adjusts the operating conditions of the optical processing mechanism (for example, the setting of the charging target potential of the primary charger 111 and the bias voltage of the developing device 112) based on the detection result of the density sensor 117.

[0017] The fixing mechanism is made up of a fixing unit 150 and a cooler 160. The fixing unit 150 includes a fixing roller 151 that applies heat to the sheet P, a pressure belt 152 that presses the sheet P against the fixing roller 151, and a post-fixing sensor 153 that detects the completion of the fixing process by the fixing unit 150. Each roller, including the fixing roller 151, is a hollow roller, and each has a heater inside. The fixing unit 150 applies heat and pressure to the toner image on the sheet while nipping and transporting the sheet P between the fixing roller 151 and the pressure belt 152, which are a pair of rotating bodies. This melts the toner particles, which then solidify, thereby fixing the image to the sheet P.

[0018] The cooler 160 is disposed downstream of the fixing device 150 in the conveying path of the sheet P. The cooler 160 prevents the optical processing mechanism from rising in temperature due to heat dissipation from the sheet P heated by the fixing device 150. The cooler 160 also prevents the sheet P from curling due to heat. The cooler 160 conveys the sheet P while absorbing heat from the sheet P with rollers 161 and 162, and is configured to promote heat dissipation from the rollers 161 and 162 with a fan (not shown). The cooler 160 has a post-cooling sensor 163 for detecting the completion of the cooling process.

[0019] The sheet P that has passed through the cooler 160 is guided by a switching flap 132 to either a first conveying path 139 or a second conveying path 133. The sheet P guided to the first conveying path 139 is discharged to the outside of the image forming apparatus 100 by a pair of discharge rollers and stacked on a discharge tray 700. The position of the sheet P carried into the second conveying path 133 is detected by a reversing sensor 137, and then a switchback operation by a reversing unit 138 switches the leading edge and trailing edge in the sheet conveying direction. Thereafter, the sheet P is guided by a switching flap 136 to either a third conveying path 135 or a re-conveying path 140. At the branching point of the third conveying path 135 and the second conveying path 133, a guide member 134 (a backflow prevention valve) is arranged to prevent the sheet P, which has been guided to the third conveying path 135 by the switching flap 136 after the switchback, from flowing back into the second conveying path 133.

[0020] A colorimetric unit 500 that measures the color of the image on the sheet is disposed on the third conveying path 135. The results of reading by the colorimetric unit 500 are used to automatically adjust the color of the image formed by the image forming unit 102. The colorimetric unit 500 is provided with a color sensor 200 that is a reading unit that reads the image on the sheet P conveyed on the third conveying path 135. The configuration of the color sensor 200 and a method of adjusting the operating conditions of the image forming unit 102 using the color sensor 200 will be described later.

[0021] In the case of double-sided printing, the sheet P with an image formed on its first side is conveyed again toward the transfer roller 114 via the re-conveyance path 140, with its leading and trailing ends swapped by the reversal unit 138. Thereafter, the sheet P with an image formed on its second side is discharged outside the image forming apparatus via the first conveyance path 139 and stacked on the discharge tray 700.

[0022] Although the image forming unit 102 of the image forming apparatus 100 in this embodiment forms an image on the sheet P by an electrophotographic process, the image forming unit 102 may use another image forming method such as an inkjet method.

[0023] <Color sensor> The image forming apparatus 100 has a built-in color sensor 200 as a reading unit capable of measuring spectral reflectance in the color measurement unit 500 provided in the third transport path 135. FIG.

[0024] The color sensor 200 includes a white LED 201 as a light source, a CMOS (Complementary Metal Oxide Semiconductor) sensor 203 that detects the intensity of the light, and an optical system that guides the light to the sensor 203. The white LED 201 irradiates a color patch 120 (patch image) formed on a sheet P with light. A diffraction grating 202 separates the reflected light 207 from the color patch 120 into wavelengths. A CMOS sensor 203 (203-1 to 203-n) consisting of n pixels measures the intensity of the light separated by the diffraction grating 202 for each wavelength. The wavelength range detectable by the CMOS sensor 203 covers substantially the entire visible light range. To acquire the reflection spectrum of the patch image P1 over a range of 380 nm to 780 nm with a resolution of 10 nm, the number of pixels n is preferably 41 or greater. To align the correspondence between the wavelength and pixel number of each imaging element, the number of pixels n is preferably 48 or 64. However, the number of pixels n may be less than 48, and the intensity of intermediate wavelengths may be calculated by interpolation.

[0025] Color sensor 200 is also provided with lens 206 for focusing reflected light 207 from color patch 120 onto diffraction grating 202. Lens 206 is an incident part through which color sensor 200 takes in light from the object to be measured. The incident part of color sensor 200 is not limited to a member such as lens 206, but may also be an opening for taking in light.

[0026] The detection signal from the CMOS sensor 203 is processed by a calculation unit 204, and the calculation results are temporarily stored in a memory 205 and then transferred to the printer controller 103. The calculation unit 204 has a spectral calculation unit that calculates the spectral reflectance of the color patch 120 by performing spectral calculation from, for example, light intensity values.

[0027] <System configuration> FIG. 3 is a block diagram showing the system configuration of image forming apparatus 100. Image forming apparatus 100 includes printer controller 103 as a control unit that controls the operation of image forming apparatus 100. Printer controller 103 is a control board on which a CPU, which is a program execution unit, and a storage device are mounted. The storage device includes a volatile storage device such as random access memory (RAM) and a non-volatile storage device such as read-only memory (ROM). Printer controller 103 also includes functional units (e.g., profile creation unit 301 and CMM (color management module) 306) for performing the functions described below. These functional units may be implemented individually as independent hardware such as an ASIC, or may be implemented in software as functional units of a program executed by the CPU of printer controller 103.

[0028] The image forming apparatus 100 is provided with an operation unit 180 that serves as a user interface. The operation unit 180 has a display that displays information to the user. The operation unit 180 also has physical keys such as a numeric keypad and a print execution button, and a touch panel function of the display, as input units that allow the user to input commands and data to the image forming apparatus 100. By operating the operation unit 180, the user can input information indicating the sheet attributes (media basis weight, media surface properties) such as the name of the sheet set in the storage 113, basis weight, and whether or not surface treatment is performed, to the printer controller 103. The input sheet attributes are registered in a sheet library stored in a storage device.

[0029] Printer controller 103 is connected to an external wired or wireless communication network via external interface (I / F) 308, and is capable of communicating with host computer 300, which is an external device. Printer controller 103 is also connected to control circuits of devices that are connected to image forming apparatus 100 and that constitute the image forming system. Examples of such devices include an image reading device that reads image information from original sheets, and a sheet processing device that performs processing such as binding and bookbinding on sheets on which images have been formed by image forming apparatus 100.

[0030] Printer controller 103 has an image processing unit 320 that generates image information used to execute an image forming operation based on data received from host computer 300. Image processing unit 320 includes a RIP (Raster Image Processor) unit 314 that develops image objects into bitmap images. Image processing unit 320 also includes a color processing unit 315 that performs color conversion processing for multi-colors, a gradation correction unit 316 that performs gradation correction for single colors, a multi-color table generation unit 317 that generates a multi-color LUT, and a maximum density condition determination unit 318 that sets the maximum image density. Each of these elements of image processing unit 320 is stored in ROM as a program module executed by the CPU of printer controller 103.

[0031] When an image formation execution instruction (image formation job) including image information is input to the printer controller 103, the image processing unit 320 performs image processing on the image information (CMYK data) that has been color converted using an ICC profile, which will be described later. When the image formation job settings specify that color conversion using an ICC profile is not to be performed, the image processing unit 320 performs image processing on the image information (CMYK data) that has not been color converted. The image information processed by the image processing unit 320 is sent to the engine control unit 312 and is used for image formation by the image forming unit 102.

[0032] The engine control unit 312 causes the image forming unit 102 to perform an image forming operation based on a command signal from the printer controller 103. The engine control unit 312 controls the conveying motor 311 and the switching flaps 132 and 136 based on detection signals from the post-fixing sensor 153, the post-cooling sensor 163, and the reversing sensor 137, and a timing signal from a timer 310. The conveying motor 311 is a group of motors that drive roller members provided in the image forming apparatus 100, and conveys a sheet by rotating the roller members.

[0033] <Color management system> A method for managing colors by feeding back the measurement results of color sensor 200 to image forming apparatus 100 will be described. In this embodiment, an ICC (International Color Consortium) profile, which has been accepted in the market in recent years as a profile that achieves excellent color reproducibility, is used. However, other color management systems may be used instead of an ICC profile.

[0034] 5 is a conceptual diagram for explaining color management using CMM. Image data input to image forming apparatus 100 does not necessarily use color representation in the L*a*b* color space, but can be represented in various data formats (colorimetric systems) such as RGB, CMYK, and CIE XYZ. Even among image data in the same data format, the perceived colors of the original image to be reproduced by image forming apparatus 100 may differ depending on the characteristics of the input device (for example, the gamma value or color temperature settings of the monitor).

[0035] Therefore, the CMM first converts the input image data into L*a*b* data expressed in a device-independent color space (in this embodiment, the CIE L*a*b* color space). The CMM then applies necessary corrections to the L*a*b* data to generate L*'a*'b*' data, which is then used to generate commands (CMYK signals) for the image forming unit to form an image. The input ICC profile is used to convert from the color system of the input device to the L*a*b* color space. The output ICC profile is used to convert from the L*a*b* color space to the color space used by the image forming unit (the space of values ​​that the CMYK signals can take). While this embodiment uses the CIE L*a*b* color space as the device-independent color space, other color spaces (e.g., the CIE 1931 XYZ color space) may be used instead.

[0036] The CMYK signals specify the exposure levels of the laser scanner unit 107 for each of the yellow, magenta, cyan, and black stations 120 to 123. In other words, the values ​​of the CMYK signals correspond to the toner density levels for each pixel of the monochrome images formed by each of the stations 120 to 123. The CMYK signals are transmitted from the printer controller 103 to the engine control unit 312, and then input to the laser scanner unit 107 as video signals.

[0037] <Profile update using color sensor> The image forming apparatus 100 of this embodiment is equipped with a color sensor 200, and is therefore capable of creating its own output ICC profile. The output ICC profile is a color conversion profile that represents the correspondence between the CMYK signals for the image forming unit 102 and the colors of the image actually formed on a sheet by the image forming unit 102.

[0038] When creating an output ICC profile for the image forming apparatus 100, color patches are formed on a sheet in a pre-specified pattern, and an image pattern for color measurement is formed on the sheet in the image forming apparatus 100. The sheet on which the image pattern has been formed is sent to the third conveying path 135, and the spectral reflectance is measured by the color sensor 200.

[0039] Next, coordinates representing the color of each patch in a device-independent color space (here, the L*a*b* color space defined by CIE) are calculated from the spectral reflectance read by color sensor 200. The coordinates in the L*a*b* color space can be calculated from the spectral reflectance using a procedure compliant with ISO 13655, for example, as shown below.

[0040] <Profile creation process> Next, the details of the profile creation process in which image forming apparatus 100 creates an ICC profile will be described. The profile creation process can be executed at any time by the user issuing an explicit instruction through operation unit 180. For example, the profile creation process is executed when a customer engineer replaces a part, before an image forming job requiring high color reproducibility is executed, or when the color of the final output product needs to be known at the design concept stage.

[0041] When an operation for creating an ICC profile is performed on the operation unit 180, a signal instructing profile creation is input to a profile creation unit 301 of the printer controller 103. The profile creation unit 301 sends a CMYK signal for outputting a 928-patch test form (CMYK color chart) defined in ISO 12642 to the engine control unit 312 without performing color conversion using the output ICC profile. In other words, in this embodiment, the test form defined in ISO 12642 is used as an image pattern (test image) for color management. In parallel with sending the CMYK signal, the profile creation unit 301 sends an instruction (colorimetry command) to the color sensor control unit 302 to measure the test form. The color sensor control unit 302 causes the color sensor 200 to measure the colors of the color patches on the test form.

[0042] The image forming apparatus 100 performs an image forming operation based on the CMYK signals input to the engine control unit 312, and forms a test form on a sheet. The sheet on which the test form has been formed is transported to the third transport path 135, and the test form is measured by the color sensor 200. The spectral reflectance data of each of the 928 patches measured by the color sensor 200 is notified to the Lab calculation unit 303 of the printer controller 103, and the Lab calculation unit 303 converts the data into data in the L*a*b* color space.

[0043] The profile creation unit 301 creates an output ICC profile by associating the CMYK signals sent to the engine control unit 312 with the color measurement results of the color sensor 200. The profile creation unit 301 also replaces the current output ICC profile stored in the storage device with the newly created output ICC profile.

[0044] The output ICC profile has a structure, for example, as shown in Figure 4, and consists of a header, tags, and their data. The profile creation unit 301 creates a CMYK to L*a*b* conversion table (A2Bx tag) based on the CMYK signals used to output the test form and the L*a*b* values ​​obtained from the colorimetric results. Furthermore, based on this conversion table, an L*a*b* to CMYK inverse conversion table (B2Ax tag) is created. Tags representing other data, such as the white point (wtpt) and a tag (gamt) that describes whether a certain color is inside or outside the color gamut of the hard copy output by the image forming apparatus 100, are also written in the output ICC profile.

[0045] When a command to execute the profile creation process is input via the external I / F 308, the ICC profile created by the profile creation unit 301 may be transmitted to the external device that issued the command. In this case, it is possible for the user to perform color conversion on the external device using an application compatible with the ICC profile.

[0046] As an index of color matching accuracy and color stability, for example, the color matching accuracy standard (IT8.7 / 4 (ISO 12642:1617 patches) [4.2.2]) specified in ISO 12647-7 specifies an average ΔE of 4.0. Furthermore, the repeatability standard [4.2.3], which specifies stability, specifies that ΔE for each patch must be 1.5 or less. To satisfy the above specifications, it is desirable for the detection accuracy of the color sensor 200 to be ΔE 1.0 or less. However, ΔE, which represents color difference, is a parameter expressed by the following formula and refers to the three-dimensional distance between two points (L1, a1, b1) and (L2, a2, b2) in the L*a*b* color space. ΔE=((L1-L2)^2+(a1-a2)^2+(b1-b2)^2)^(1 / 2) <Color conversion processing> Next, we will explain the color conversion process performed on input image data when an image formation job commanding image formation is submitted to the image forming apparatus 100. In the block diagram shown in FIG. 3, image data received by the printer controller 103 via the external I / F 308 is input to the input-side conversion unit 307. In typical color printing, image data is often expressed using RGB values ​​or standard printing CMYK signal values ​​such as JapanColor. In this case, the input-side conversion unit 307 of the CMM 306 converts the input image data into L*a*b* data by performing color conversion from RGB to L*a*b* or CMYK to L*a*b* using an input ICC profile. The input ICC profile is composed of a one-dimensional LUT (lookup table) that controls the gamma of the input signal, a multi-color LUT known as direct mapping, and a one-dimensional LUT that controls the gamma of the generated conversion data.

[0047] The CMM 306 performs necessary corrections on the L*a*b* data to adjust the color of the output. An example of such correction processing is GAMUT conversion, which corrects mismatches between the color gamut of the input device and the color gamut reproducible by the image forming apparatus 100. Another example is color conversion, which adjusts mismatches between the light source type on the input side and the light source type used to observe the output of the image forming apparatus 100 (also known as color temperature setting mismatches). Yet another example is black text determination, which identifies text in a color image and converts it to a color appropriate for the text to improve the readability of the text in the output. These correction processes convert the L*a*b* data to L*'a*'b*' data. Furthermore, even when input image data input via the external I / F 308 is expressed in the L*a*b* color space, the CMM 306 performs correction processing as necessary to convert it to L*'a*'b*' data.

[0048] The output-side converter 305 converts the L*'a*'b*' data received from the CMM 306 into a CMYK signal by performing L*a*b*->CMYK color conversion based on the output ICC profile. If the profile creation unit 301 updates the output ICC profile, the CMYK signals generated before and after the update will be different, even if the L*'a*'b*' data is the same. In other words, the output ICC profile, which is an image formation condition for the image forming apparatus 100, is changed based on the measurement results of the color sensor 200. While the input-side converter 307 and the output-side converter 305 are shown as separate components from the CMM 306 in FIG. 3, the CMM, as shown in FIG. 5, refers to the entire module that performs color management by performing color conversion using the input and output profiles.

[0049] <Opposite roller configuration> Next, the configuration of the opposing roller 601 will be described with reference to Fig. 6 to Fig. 13. Fig. 6(a) is a diagram showing the opposing roller 601 and color sensor 200 when the opposing roller 601 is located at the separation position. Fig. 6(b) is a diagram showing the opposing roller 601 and color sensor 200 when the opposing roller 601 is located at the abutting position. Fig. 6(c) is an enlarged view of the transport guide hole 602 when the opposing roller 601 is located at the abutting position.

[0050] As shown in FIG. 6, the third transport path 135 is formed by a first transport guide 135a and a second transport guide 135b. The second transport guide 135b is provided at a position facing the first transport guide 135a and forms the third transport path 135 together with the first transport guide 135a. The color sensor 200 is disposed on the reverse side of the surface of the first transport guide 135a that faces the sheet P (the paper transport surface). The first transport guide 135a is provided with a transport guide hole 602 that is an opening through which the color sensor 200 detects color patches on the sheet P. The color sensor 200 reads the patch image formed on the sheet P through the transport guide hole 602 provided in the first transport guide 135a. Note that the first transport guide 135a may be made up of multiple members, and the opening may be formed by the gap between these members.

[0051] The third conveying path 135 is provided with a first conveying roller pair 501 arranged upstream of the color sensor 200 in the conveying direction, and a second conveying roller pair 502 arranged downstream of the color sensor 200. The first conveying roller pair 501 and the second conveying roller pair 502 are conveying members that convey the sheet in the third conveying path 135.

[0052] In the color measurement unit 500, four color sensors 200 are arranged at intervals in the width direction perpendicular to the conveying direction (not shown). The color measurement unit 500 is capable of reading patch images formed on the sheet P with the four color sensors 200 while conveying the sheet P with a first conveying roller pair 501 and a second conveying roller pair 502.

[0053] An opposing roller 601, which is an opposing member, is disposed at a position facing the reading position of the color sensor 200. The opposing roller 601 is supported rotatably around an opposing roller shaft 601a, which is a rotation shaft. The opposing rollers 601 are provided at positions corresponding to the four color sensors 200 (see FIG. 8, which will be described later). The opposing roller 601 is configured to be movable between a spaced position (position shown in FIG. 6A) where it does not contact the first transport guide 135a, and a contact position (position shown in FIG. 6B) where it contacts the first transport guide 135a. The movement mechanism of the opposing roller 601 will be described later. The contact position, which is the first position, is a position where the opposing roller 601 is close to (opposes) the lens 206 of the color sensor 200. The separated position, which is the second position, is a position where the opposing roller 601 is farther away from the lens 206 of the color sensor 200 than the contact position. The opposing roller 601 is a sponge roller made of a sponge material, which is an elastic material, and the opposing roller 601 can convey a sheet by rotating in a state of contacting the first conveying guide 135a at the contact position.

[0054] In a normal print job that does not include measurement by the colorimetric unit 500, the opposing roller 601 moves to the separated position to prevent wear of the sponge material. On the other hand, in a colorimetry adjustment job that includes measurement by the colorimetric unit 500, the opposing roller 601 moves to the contact position and contacts the first conveyance guide 135a. When a sheet P is conveyed in a colorimetry adjustment job, the opposing roller 601 urges the sheet P against the conveyance guide hole 602 of the first conveyance guide 135a, and regulates the position of the sheet P to be at the focal position α of the color sensor 200. At this time, as shown in FIG. 6(c), a portion of the opposing roller 601 is inserted into the conveyance guide hole 602.

[0055] 7A and 7B are side views of the opposing roller 601 held by the swing arm 603, with Fig. 7A showing the opposing roller 601 in the separated position and Fig. 7B showing the opposing roller 601 in the contact position. Fig. 8 is a perspective view of the opposing roller 601 and the swing arm 603.

[0056] 8, a swing arm 603, which is a holding member, supports both ends of the opposing roller shaft 601a. ​​The swing arm 603 is composed of a front swing arm 603F (first holding part) that supports the front end of the opposing roller shaft 601a, and a rear swing arm 603R (second holding part) that supports the rear end of the opposing roller shaft 601a. ​​A plurality of opposing rollers 601 are arranged between these two swing arms 603 at intervals in the width direction.

[0057] The swing arm 603 can swing around a swing center shaft 604, which is the swing axis, as the center of rotation. The swing arm 603 swings, allowing the opposing roller 601 to move between a separated position and an abutting position. The swing arm 603 is provided with an abutting portion 603a that abuts against the first transport guide 135a. When viewed from the axial direction of the opposing roller shaft 601a, the abutting portion 603a is an arc-shaped abutting surface centered on the opposing roller shaft 601a. ​​As shown in FIG. 7(a), when the opposing roller 601 is in the retracted position, the abutting portion 603a is spaced from the first transport guide 135a. As shown in FIG. 7(b), when the opposing roller 601 moves from the retracted position to the abutting position, the abutting portion 603a abuts against the first transport guide 135a.

[0058] The contact radius r1, which is the distance between the center of the opposing roller shaft 601a and the contact portion 603a, is set to be smaller than the opposing roller radius r2. In this embodiment, the difference between the contact radius r1 and the opposing roller radius r2 is 0.5 mm, but this may be set to an appropriate value depending on the hardness of the sponge roller and the size of the device.

[0059] When the opposing roller 601 is in the contact position, the distance from the opposing roller shaft 601a (the rotation center of the opposing roller 601) to the first conveying guide 135a is the contact radius r1. In other words, the distance from the opposing roller shaft 601a to the lens 206 of the color sensor 200 is determined by the contact portion 603a.

[0060] 9(a) is a cross-sectional view of the front swing arm 603F, and FIG. 9(b) is a cross-sectional view of the rear swing arm 603R. The contact portions 603 are provided on both the front swing arm 603F and the rear swing arm 603R, and are referred to as the front contact portion 603Fa and the rear contact portion 603Ra, respectively. The front contact portion 603Fa and the rear contact portion 603Ra are disposed so as to contact the first conveying guide 135a on the outer side in the width direction of the sheet passing area Ws through which the sheet is conveyed in the third conveying path 135 (see FIG. 8). As a result, regardless of the size of the sheet being conveyed, the front contact portion 603Fa and the rear contact portion 603Ra do not come into contact with the sheet.

[0061] As shown in Fig. 9(b), the rear swing arm 603R is prevented from rotating by a pin 604b extending from the swing center shaft 604 so as to rotate integrally with the swing center shaft 604. On the other hand, as shown in Fig. 9(a), the front swing arm 603F is formed with a groove 618 so as to be swingable about the swing center shaft 604 with respect to a pin 604a extending from the swing center shaft 604, and is configured to be swingable at an angle θa with respect to the swing center shaft 604. In other words, the rear swing arm 603R cannot rotate about the swing center shaft 604, but the front swing arm 603F can rotate about the swing center shaft 604. The rotation of the front swing arm 603F about the swing center shaft 604 is restricted within the range of angle θa by a wall 618a, which is a restricting portion of the groove 618.

[0062] The swing center shaft 604 is supported by bearings 605 and 606. A pressure lever 607 is fixed to the swing center shaft 604 between the front swing arm 603F and the rear swing arm 603R of the swing center shaft 604. A pressure spring 608, which is a biasing member, is provided at the tip of the pressure lever 607, and the pressure lever 607 is pulled by the pressure spring 608, thereby biasing the opposing roller 601 toward the first transport guide 135a. A torsion coil spring 609 is disposed near the front swing arm 603F of the swing center shaft 604, and the torsion coil spring 609 applies a force in a direction that biases the front swing arm 603F toward the first transport guide 135a. Furthermore, a transport drive gear 610 is fixed to the rear end of the opposing roller shaft 601a, and drive force is transmitted via an idler gear 611 that rotates around the swing central shaft 604.

[0063] Next, the roller separation cam 613 that moves the opposing roller 601 between the contact position and the separation position will be described with reference to Fig. 10. Fig. 10(a) shows the roller separation cam 613 in a state where the opposing roller 601 is located at the separation position, and Fig. 10(b) shows the roller separation cam 613 in a state where the opposing roller 601 is located at the contact position.

[0064] The roller separation cam 613 is disposed near the pressure lever 607 on the rear side of the paper conveyance surface of the second conveyance guide 135b, and rotates around a roller separation cam shaft 613a. When the opposing roller 601 moves to the separated position, the roller separation cam 613 rotates, and the top dead center 613b of the roller separation cam 613 presses down the convex portion 607a of the pressure lever 607, thereby moving the opposing roller 601. On the other hand, when the opposing roller 601 moves to the abutting position, the roller separation cam 613 rotates to a position where it does not come into contact with the convex portion 607a of the pressure lever 607. As a result, the pressure lever 607 is pulled by the pressure spring 608, and the opposing roller 601 is pressed against the first conveyance guide 135a.

[0065] Next, a drive transmission mechanism for driving and rotating the roller separating cam 613 will be described with reference to Figures 11 and 12. Figure 11 is a perspective view of the roller separating cam 613, and Figure 12 is a perspective view of the drive transmission mechanism between the roller separating cam 613 and the opposing roller 601. An HP sensor flag 615 for detecting the rotational position of the roller separating cam 613 is fixed to the roller separating cam shaft 613a so as to be rotatable integrally with the roller separating cam 613. The roller separating cam shaft 613a is supported by bearings 618 and 616. A one-way clutch gear 619 is provided at the end of the roller separating cam shaft 613a.

[0066] The opposing roller 601 is driven to rotate by a driving force transmitted from a drive input gear (not shown) via idler gears 612 and 611 and a conveyance drive gear 610. A one-way clutch gear 619 on the roller separation cam shaft 613a is drivingly connected to the idler gear 611, and is configured to transmit only the rotational drive force in the direction opposite to the sheet conveyance direction (arrow A) to the roller separation cam shaft 613a. In addition, a torque limiter 617 is disposed on the roller separation cam shaft 613a to generate a predetermined braking force when the roller separation cam shaft 613a and the roller separation cam 613 are driven to rotate. One end of the torque limiter 617 is connected to a bearing 616, and the other end is fixedly connected to the roller separation cam shaft 613a. The torque limiter 617 can hold the roller separation cam 613 in a predetermined position even when no driving force is transmitted to the roller separation cam shaft 613a. Further, a separating cam HP sensor 614 for detecting the HP sensor flag 615 is disposed near the HP sensor flag 615 and is used to detect the position of the roller separating cam 613 .

[0067] Next, drive transmission to the opposing roller 601 during sheet conveyance will be described with reference to FIG. 13. FIG. 13 is a cross-sectional view of the drive transmission mechanism of the opposing roller 601 disposed near the rear swing arm 603R. The opposing roller 601 contacts the first conveyance guide 135a and conveys the sheet in the direction of arrow S (conveyance direction). A swing central shaft 604, which is the rotation center of the swing arm 603, is located upstream of the rotation center of the opposing roller 601 in the conveyance direction. Therefore, when the idler gear 611 is driven to rotate in the direction of arrow B around the swing central shaft 604, the idler gear 611 generates a force in a direction pressing the opposing roller 601 against the first conveyance guide 135a via the conveyance drive gear 610. This makes it possible to reliably bias the opposing roller 601 against the first conveyance guide 135a.

[0068] <Color measurement adjustment job control flow> Fig. 14 is a flowchart of the control executed by the printer controller 103 during a color measurement adjustment job. When a color measurement adjustment job is submitted, the printer controller 103 starts the processing of the flowchart in Fig. 14. First, the printer controller 103 starts feeding sample paper on which color patches will be printed (S1001). Then, the image forming unit 102 prints the color patches on the sample paper (S1002).

[0069] Next, the printer controller 103 moves the opposing roller 601 from the separated position to the contact position by driving the conveying motor 311 in the direction opposite to the sheet conveying direction so that the opposing roller 601 contacts the first conveying guide 135a (S1003).

[0070] Next, the printer controller 103 determines whether the sample paper on which the color patches have been fixed has reached the colorimetry unit 500 (S1004). If the sample paper has not reached the colorimetry unit 500 (No in S1004), the printer controller 103 waits until the sample paper reaches the colorimetry unit 500. If the sample paper has reached the colorimetry unit 500 (Yes in S1004), the printer controller 103 reads the color patches printed on the sample paper with the color sensor 200 (S1005).

[0071] When color measurement by the color sensor 200 is completed, the sample paper is discharged to the discharge tray 700 (S1006). Then, the printer controller 103 moves the opposing roller 601 from the contact position to the separation position (S1007), and the color measurement adjustment job is completed.

[0072] <Explanation of Effects of This Embodiment> As described above, when the opposing roller 601 moves to the contact position, the contact portion 603a of the swing arm 603 contacts the first transport guide 135a, directly determining the distance between the first transport guide 135a and the center of rotation of the opposing roller 601. This makes it possible to accurately manage the amount of compression of the sponge of the opposing roller 601, and as a result, the contact pressure of the opposing roller 601 against the first transport guide 135a is also managed to be constant. In other words, it is possible to stabilize the dynamic position of the sheet during skimming with respect to the focus position α of the color sensor 200, and it is possible to improve the accuracy of reading by the color sensor 200.

[0073] Furthermore, the front-side swing arm 603F can swing within a range of angle θa relative to the swing central axis 604. With this configuration, even if the distance of the swing central axis 604 relative to the first transport guide 135a differs between the front and rear sides of the device due to dimensional tolerances of parts, the front-side swing arm 603F abuts against the first transport guide 135a while equalizing the difference. This allows both the front-side swing arm 603F and the rear-side swing arm 603R to always abut against the first transport guide 135a in a stable manner, and as a result, the amount of compression of the sponge of the opposing roller 601 can always be stabilized on the front and rear sides.

[0074] Furthermore, when the sheet is conveyed by pressing it against the first conveying guide 135a by the opposing roller 601, a force is generated in the direction pressing the opposing roller 601 against the first conveying guide 135a by the drive mechanism that rotates the opposing roller 601. This ensures that the opposing roller 601 is pressed against the first conveying guide 135a.

[0075] Furthermore, in the above-described embodiment, four color sensors 200 are provided, and therefore four opposing rollers 601 are also arranged to face each other, but the number of color sensors 200 and opposing rollers 601 is not limited to this. For example, if there are two color sensors 200, there will also be two opposing rollers 601, and the same effect as described above can be obtained in this case as well. In other words, the same effect can be obtained even if the number of opposing rollers 601 is increased or decreased. Furthermore, the same effect can be obtained by arranging one wide sponge roller to face multiple color sensors 200. [Explanation of symbols]

[0076] 100 Image forming device 200 Color Sensor 135a First transport guide 135b Second transport guide 601 Opposing roller 603 Swing Arm

Claims

1. an image forming unit that forms an image on a sheet; a first conveyance guide having an opening and forming a conveyance path along which a sheet having an image formed thereon by the image forming unit is conveyed; a second transport guide provided at a position opposite to the first transport guide and forming the transport path together with the first transport guide; a reading unit that reads an image on the sheet conveyed through the conveyance path through the opening; an opposing member that faces the reading unit at a reading position of the reading unit; a holding member that holds the opposing member movably between a first position facing the reading unit and a second position that is farther away from the reading unit than the first position; Equipped with the holding member includes a contact portion that contacts the first transport guide when the opposing member is located at the first position; An image forming apparatus characterized by:

2. the opposing member includes a rotatably provided opposing roller and a rotation shaft supporting the opposing roller, a distance between the rotation shaft and the first transport guide when the opposing member is located at the first position is determined by the abutment portion abutting against the first transport guide; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. When the opposing member is located at the first position, a portion of the opposing roller is inserted into the opening.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. the opposing member abuts against the first transport guide at the first position; 4. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

5. the contact portion has a contact surface that is arc-shaped with its center at the rotation center of the opposing roller when viewed from the axial direction of the rotation shaft, a distance from the rotation center of the opposing roller to the contact surface is smaller than a radius of the opposing roller; 5. The image forming apparatus according to claim 2, wherein the image forming apparatus comprises: a first fixing member;

6. The opposing roller is made of sponge.

6. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

7. a swing shaft that swingably supports the holding member, The holding member swings about the swing axis so as to move the opposing member between the first position and the second position.

7. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

8. the holding member includes a first holding portion rotatable about the swing shaft and a second holding portion fixed to the swing shaft, The first holding portion has a restricting portion that restricts rotation of the first holding portion.

8. The image forming apparatus according to claim 7,

9. the opposing member includes a rotatably provided opposing roller and a rotation shaft supporting the opposing roller, a swing shaft provided upstream of the rotation shaft in the sheet conveying direction and swingably supporting the holding member; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

10. the contact portion contacts the first conveyance guide outside a region in the conveyance path through which the sheet passes, in a width direction perpendicular to the sheet conveyance direction; 10. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

11. a biasing member that biases the opposing member toward the first transport guide; 11. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

12. a cam that is rotatably supported and that moves the opposing member between the first position and the second position by rotating; 12. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

13. a control unit that adjusts image forming conditions of the image forming unit based on the reading result of the reading unit; 13. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: a first fixing member;

14. An image reading device that reads an image on a sheet on which an image is formed by an image forming unit, a first conveyance guide having an opening and forming a conveyance path along which a sheet having an image formed thereon by the image forming unit is conveyed; a second transport guide provided at a position opposite to the first transport guide and forming the transport path together with the first transport guide; a reading unit that reads an image on the sheet conveyed through the conveyance path through the opening; an opposing member that faces the reading unit at a reading position of the reading unit; a holding member that holds the opposing member movably between a first position facing the reading unit and a second position that is farther away from the reading unit than the first position; Equipped with the holding member includes a contact portion that contacts the first transport guide when the opposing member is located at the first position; An image reading device characterized by:

Images