Image reading device and image forming system

Abstract

Suppresses the decrease in accuracy of shading correction. [Solution] The image reading device comprises a reading unit 301 for reading an image formed on a sheet, a white reference plate 305 that is read by the reading unit 301 when shading correction is performed, a reading glass 304 that is positioned in the direction in which the reading unit 301 reads the sheet, prevents foreign matter from adhering to the reading unit 301, and to which the white reference plate 305 is attached, and a support member (314) that supports the reading glass 304 at both ends in the main scanning direction. When shading correction is performed, the support member (314) moves, causing the white reference plate 305 attached to the reading glass 304 to move to a first position where the sheet is located when the sheet is read.

Description

Technical Field

[0001] The present invention relates to an image reading apparatus that reads an image formed on a sheet, and an image forming system including such an image reading apparatus.

Background Art

[0002] In the commercial printing field and the industrial printing field, the printing machine market is expanding. Printing methods of such printing machines (image forming systems) include an electrophotographic method that is also spreading to the offset printing market, and an inkjet method that has succeeded in opening a wide market with large format, low initial cost, ultra-high speed, etc.

[0003] Among inkjet printers, for example, there is a line head type recording device that prints an image on a sheet by a recording head fixed to the main body discharging liquid droplets in conjunction with the conveyed sheet. When using a line head type recording device in the commercial printing field or the industrial printing field where image quality is required, an image reading apparatus is provided on the downstream side of the recording head in the sheet conveyance direction. The image reading apparatus reads an image formed on the sheet. The reading result by the image reading apparatus is used for detecting poor discharge of liquid droplets by the recording head, color misregistration, uneven image density, and adjusting geometric characteristics of the image to be printed. Here, the geometric characteristics of the image refer to the shape, position, etc. of the image.

[0004] The image reading apparatus includes an image sensor including a light source and an optical conversion element. The image reading apparatus receives the reflected light of the light irradiated from the light source to the sheet by the light source conversion element, and outputs the received result as a reading result. The image reading apparatus performs shading correction for correcting variations in the light amount distribution of the irradiation light of the light source and individual differences for each photoelectric conversion element in order to obtain a stable reading result. The image reading apparatus reads a white reference plate that serves as a white reference during shading correction.

[0005] When reading the white reference plate during shading correction, it is preferable that the distance between the image sensor and the white reference plate matches the distance between the image sensor and the sheet when reading the sheet's image. If these distances are different, high-precision shading correction cannot be performed, making high-precision image correction difficult. In Patent Document 1, when performing shading correction, the white reference plate is moved between the image sensor and the mounting surface on which the sheet to be read is placed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-76748 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the image sensor used in the image reading device generates measurement errors due to the difference between the first distance to the white reference plate and the second distance to the surface of the sheet. For this reason, it is preferable to make the first and second distances the same to suppress measurement errors. In addition, the image sensor is provided with a transparent member (reading glass) to prevent the adhesion of fine foreign matter such as paper dust. The reading glass is positioned adjacent to the bottom plate located on the light irradiation side of the image sensor. The white reference plate is attached to the reading glass.

[0008] The bottom plate of an image sensor is mainly made of resin or metal and is subject to slight deformation due to the temperature inside the printing press. This deformation of the bottom plate changes the position of the reading glass fixed to it. This causes a difference between the first and second distances, making high-precision shading correction difficult. This results in a decrease in the image quality of the reading result (read image) by the image reading device.

[0009] In view of the above-mentioned problems, the primary objective of the present invention is to provide an image reading device that suppresses the reduction in accuracy of shading correction. [Means for solving the problem]

[0010] The image reading device of the present invention comprises: a transport means for transporting a sheet on which an image is formed; a reading means for reading the image formed on the sheet transported by the transport means; a transparent member provided between the position where the transport means transports the sheet and the reading means; a reference member provided on the transparent member and read by the reading means; a support member supporting the transparent member at both ends in a direction intersecting the transport direction of the sheet by the transport means; a moving means for moving the support member to move the reference member attached to the transparent member to a first position where the sheet is located when the sheet is read, when performing shading correction; and moving the support member to move the reference member attached to the transparent member from the first position to another second position when the reading means reads the image formed on the sheet, wherein the reading means reads the sheet transported to the first position by the transport means when reading the image formed on the sheet, and reads the reference member moved to the first position by the moving means when performing shading correction. The image forming system of the present invention comprises a conveying means for conveying a sheet, an image forming means for forming an image on the sheet conveyed by the conveying means, and an image reading device for reading the sheet on which the image has been formed by the image forming means, wherein the image reading device comprises a reading means for reading the image formed on the sheet conveyed by the conveying means, a reference member read by the reading means when performing shading correction, a transparent member provided in the direction in which the reading means reads the sheet and prevents foreign matter from adhering to the reading means, to which the reference member is attached, and a support member that supports the transparent member at both ends in a direction intersecting the conveying direction of the sheet by the conveying means, and the shading The reading means includes a moving means that moves the support member to move the reference member attached to the transparent member to a first position where the sheet is located when the sheet is read, when the reading means reads the image formed on the sheet, and moves the support member to move the reference member attached to the transparent member from the first position to another second position, wherein the reading means reads the sheet that has been transported to the first position by the transport means when reading the image formed on the sheet, and reads the reference member that has been moved to the first position by the moving means when performing shading correction. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress the decrease in accuracy of shading correction. [Brief explanation of the drawing]

[0012] [Figure 1] Configuration diagram of an inkjet recording device. [Figure 2] A diagram illustrating the configuration of a printed circuit board. [Figure 3] (a) and (b) are explanatory diagrams of the inline scanner unit. [Figure 4] A view of the inner box from the image-forming surface side. [Figure 5](a) and (b) are diagrams illustrating the operation of the inline scanner unit. [Figure 6] Cross-sectional view of an inline scanner unit. [Figure 7] Diagram of the control board. [Figure 8] (a) to (c) are explanatory diagrams of the glass movement mechanism. [Figure 9] Diagram illustrating the holding mechanism of the glass movement section. [Modes for carrying out the invention]

[0013] Preferred embodiments of the present invention will be described below with reference to the attached drawings.

[0014] Figure 1 is a diagram of the configuration of an inkjet recording device, which is an image forming system according to this embodiment. This inkjet recording device 10 is a printing press used, for example, in the commercial printing or industrial printing fields. The inkjet recording device 10 ejects ink onto a sheet, which is a cut-paper-like recording material, to form an image. The inkjet recording device 10 of this embodiment uses two liquids, a reaction solution and ink, to form an ink image on the sheet and produce a finished product. The sheet can be any ink-receiving recording material, such as plain paper, cardboard, plastic film for overhead projectors, specially shaped sheets such as envelopes or index paper, or cloth.

[0015] The inkjet recording device 10 comprises a paper feed module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inversion module 6000, and a paper discharge and stacking module 7000. Sheets are supplied from the paper feed module 1000, predetermined image formation processes are performed in each module, and the sheets are discharged to the paper discharge and stacking module 7000. In this embodiment, the inkjet recording device 10 is configured by each module having a separate housing, and these housings being connected. However, the inkjet recording device 10 may also contain the functions of each module within a single housing.

[0016] The paper feeding module 1000 includes a plurality (three stages in this embodiment) of storage compartments 1100a to 1100c. Each of the storage compartments 1100a to 1100c can store sheets. Each of the storage compartments 1100a to 1100c is configured to be pullable out toward the front side of the apparatus, and is pulled out toward the front side of the apparatus to store sheets. The paper feeding module 1000 feeds sheets to the printing module 2000 one by one. For this purpose, a separation belt and conveying rollers are provided in each of the storage compartments 1100a to 1100c. Note that the number of the storage compartments 1100a to 1100c is an example, and it may be one stage, two stages, or four stages or more.

[0017] The printing module 2000 functions as an image forming apparatus that forms an image on the sheet fed from the paper feeding module 1000. The printing module 2000 includes a pre-image registration correction unit 2100, a printing belt unit 2200, and a recording unit 2300. The pre-image registration correction unit 2100 corrects the inclination and position of the sheet supplied from the paper feeding module 1000 and conveys it to the printing belt unit 2200.

[0018] The printing belt unit 2200 and the recording unit 2300 are arranged to face each other across the sheet conveying path on the downstream side of the pre-image registration correction unit 2100 in the sheet conveying direction. The printing belt unit 2200 adsorbs and conveys the sheet conveyed from the pre-image registration correction unit 2100. The recording unit 2300 is a sheet processing unit that performs a recording process (printing) on the sheet conveyed by the printing belt unit 2200 from above with a recording head to form an image. The recording head performs printing by discharging ink onto the sheet. The sheet is adsorbed and conveyed by the printing belt unit 2200, so that the clearance with the recording head is kept constant.

[0019] Multiple recording heads are arranged along the sheet transport direction. In this embodiment, the recording heads consist of four colors: Y (yellow), M (magenta), C (cyan), and K (black), plus five line-type recording heads corresponding to the reaction solution. Note that the number of colors and recording heads are not limited to five. The inkjet method can employ a method using a heating element, a piezoelectric element, an electrostatic element, or a MEMS (Micro Electro Mechanical Systems) element. The ink for each color is supplied to the recording head from an ink tank (not shown) via an ink tube. The ink contains, for example, 0.1% to 20.0% by mass of resin components, water, a water-soluble organic solvent, a colorant, wax, additives, etc., based on the total mass.

[0020] The sheets printed by the recording unit 2300 are transported by the print belt unit 2200. An inline scanner unit 1 is positioned downstream of the recording unit 2300 in the transport direction. The inline scanner unit 1 is an image reading device used to correct the printed image by detecting positional misalignment and color density of the image formed on the sheet.

[0021] For example, the inline scanner unit 1 reads the sheet (read image), and the marks formed on the edges of the sheet and the coordinates of the four corners of the sheet are detected. Based on these detection results, the geometric characteristics of the image, such as right angles, skew, front registration, left registration, main magnification, and sub-magnification, are adjusted to correct image misalignment. In addition, the inline scanner unit 1 reads the sheet (read image), and the pixel values ​​(luminance values) of the image density adjustment images formed on the sheet are analyzed. Based on the analysis results, the amount of ink ejected by the recording head is adjusted to correct the color density.

[0022] The drying module 3000 dries the sheet on which the image has been formed by the printing module 2000 by blowing hot air onto the sheet. By drying the sheet, the drying module 3000 reduces the liquid component contained in the ink, thereby improving the adhesion between the sheet and the ink. The drying module 3000 comprises a decoupling unit 3200, a drying belt unit 3300, and a hot air blowing unit 3400.

[0023] The sheet printed in the recording unit 2300 of the print module 2000 is transported to the decoupling unit 3200 in the drying module 3000. The decoupling unit 3200 loosely holds and transports the sheet using the frictional force generated between the sheet and the belt by the pressure of the wind blown from above. As a result, the sheet straddles the decoupling unit 3200 and the print belt unit 2200, preventing any displacement of the portion remaining on the print belt unit 2200.

[0024] The sheet conveyed from the decoupling unit 3200 is adsorbed and conveyed to the drying belt unit 3300, and at the same time, hot air is blown from the hot air blowing unit 3400 located above the belt to dry the ink-applied surface (the printed surface of the image). The ink and reaction liquid applied to the sheet are heated, and the evaporation of moisture is promoted, so the sheet absorbs the applied ink, and the occurrence of so-called cockling, where the sheet stretches locally and wrinkles, can be suppressed. For the heater that heats the air, for example, an electric heating wire or an infrared heater is preferred from the viewpoint of safety and energy efficiency. In addition to the method of applying hot air, the drying method may also be a method that combines a method of irradiating the sheet surface with electromagnetic waves (ultraviolet rays or infrared rays, etc.) or a method of conduction heat transfer by contact with a heating element.

[0025] The fixing module 4000 fixes the image to the sheet by heating the sheet dried by the drying module 3000 to dry the ink. The fixing module 4000 includes a fixing belt unit 4100 having an upper belt unit and a lower belt unit. The fixing module 4000 passes the sheet conveyed from the drying module 3000 between the heated upper belt unit and the lower belt unit, thereby allowing the ink solvent to sufficiently penetrate (fix) into the sheet.

[0026] The cooling module 5000 cools the sheet on which the image has been fixed by the fixing module 4000, thereby solidifying the ink that has softened due to heating and suppressing temperature changes of the sheet caused by downstream equipment. The cooling module 5000 is equipped with multiple cooling units 5100. The multiple cooling units 5100 cool the high-temperature sheet conveyed from the fixing module 4000. Each cooling unit 5100 increases the pressure inside the cooling box by drawing in outside air with a fan. The air inside the cooling box is blown out from nozzles formed in the conveying path and directed onto the sheet, cooling the sheet. The multiple cooling units 5100 are arranged on both sides of the conveying path, allowing the sheet to be cooled from both sides.

[0027] A transport path switching unit is provided within the cooling module 5000. The transport path switching unit switches the transport path of the sheet depending on whether the sheet is being transported to the inversion module 6000 or to the double-sided transport path used during double-sided printing.

[0028] During double-sided printing, the sheet is transported to a transport path below the cooling module 5000 and then transported through the double-sided transport path of the fuser module 4000, drying module 3000, print module 2000, and paper feed module 1000. The double-sided transport section of the fuser module 4000 is provided with a first inversion section 4200 that inverts the front and back sides of the sheet. After being transported to the first inversion section 4200, the sheet is inverted and transported to the drying module 3000 side, thereby inverting the printed side of the image. By passing through the first inversion section 4200, printing on the back side of the sheet becomes possible. After that, the sheet is transported again to the pre-image registration correction section 2100, print belt unit 2200, and recording section 2300 of the print module 2000 for printing.

[0029] The inversion module 6000 includes a second inversion unit 6400. The inversion module 6000 can invert the front and back sides of the conveyed sheets using the second inversion unit 6400. This allows the orientation of the front and back sides of the discharged sheets to be changed. The output and stacking module 7000 includes a top tray 7200 and a stacking tray 7500. The output and stacking module 7000 aligns and stacks the sheets conveyed from the inversion module 6000 onto the top tray 7200 or the stacking tray 7500.

[0030] (Print Module) Figure 2 is a diagram of the print module 2000. As described above, the print module 2000 comprises a pre-image registration correction unit 2100, a print belt unit 2200, and a recording unit 2300. The sheet S, whose orientation has been corrected by the pre-image registration correction unit 2100, is printed by the recording unit 2300 directly below the recording head 100. The sheet S is transported by suction and adsorption by the print belt unit 2200, so that its transport behavior is stable directly below the recording head 100.

[0031] The print belt unit 2200 includes an endless print belt 25 stretched over tension rollers 21, 22, 23, and 24. The belt surface of the print belt 25 stretched over tension rollers 21 and 24 becomes an image forming surface 26 for image formation directly below the recording head 100. The print belt 25 rotates so that the image forming surface 26 moves in the direction of conveying the sheet S. The print belt 25 is provided with numerous suction holes (not shown) for attracting the sheet S.

[0032] The print belt 25 uses suction holes located on the image forming surface 26 to attract and hold the sheet S, and then rotates to transport the held sheet S. In other words, the image forming surface 26 is also a transport surface for transporting the sheet S. The print belt 25 also functions as a transport means for carrying and transporting the sheet S on which the image has been formed. For this purpose, a suction device (not shown) is provided at a position surrounded by the print belt 25 to attract and hold the sheet S to the suction holes on the image forming surface 26. The print belt 25 is created, for example, by forming suction holes in a single PET sheet wound into a roll, cutting it to a predetermined length, and then joining the ends by laser welding.

[0033] The sheet S, which is adsorbed onto the image forming surface 26, is transported with a predetermined print gap between it and the recording head 100. As described above, the recording head 100 has five line-type recording heads arranged along the transport direction of the sheet S, corresponding to the four colors Y (yellow), M (magenta), C (cyan), and K (black), as well as the reaction solution. Note that the number of recording heads 100 is not limited to five; for example, it may be eight line-type recording heads, each having recording heads corresponding to three additional spot colors. An in-line scanner unit 1 is positioned downstream of the recording head 100 in the transport direction of the sheet S.

[0034] (In-line scanner unit) Figure 3 is an explanatory diagram of the inline scanner unit 1. Figure 3(a) is an external perspective view of the inline scanner unit 1. Figure 3(b) is an exploded view of the inline scanner unit 1. The inline scanner unit 1 includes an inner casing 1b, an outer casing 1d, and a glass moving part 1c.

[0035] The inline scanner unit 1 is equipped with an inner box movement restricting member 313 on its front plate 316. The inner box movement restricting member 313 restricts the horizontal movement of the inner box 1b. The horizontal direction is parallel to the image forming surface 26. The inline scanner unit 1 is positioned in the print module 2000 such that the inner box movement restricting member 313 (front plate 316) faces the front side of Figure 2, and the rear plate 317 faces the back side of Figure 2.

[0036] The inner box 1b is equipped with two reading units 301, which are image sensors for optically reading images. Figure 4 is a view of the inner box 1b from the image forming surface 26 side. The two reading units 301 are arranged side by side in a direction intersecting the transport direction of the sheet S. Note that the positions of the two reading units 301 in the transport direction are different. With this arrangement, the two reading units 301 can read the entire area in the direction intersecting the transport direction of the sheet S. The inner box 1b is provided with two control boards 302 for controlling the two reading units 301. There is a one-to-one correspondence between the two reading units 301 and the two control boards 302.

[0037] The inner box 1b is provided with two inner box short axes 303 and an inner box long axis 312. During shading correction, the inner box 1b moves vertically due to the two inner box short axes 303. The upward direction is away from the image forming surface 26, and the downward direction is towards the image forming surface 26. The inner box long axis 312 restricts the movement of the inner box 1b in the transport direction (left and right). The left direction is downstream in the transport direction of the sheet S, and the right direction is upstream in the transport direction of the sheet S. The inner box long axis 312 engages with the inner box movement restricting member 313 of the housing. As a result, vertical movement of the inner box 1b is permitted, but horizontal movement is restricted.

[0038] The outer casing 1d comprises a motor 308, a photosensor 309, two cams 310, and a shaft 311. The two cams 310 are located at both ends (front and back) in a direction intersecting the conveying direction of the sheet S. The glass moving member 306, described later, contacts the circumferential surfaces (surfaces parallel to the axis of rotation) of the two cams 310. As a result, the motor 308 is driven to rotate the two cams 310, pushing the glass moving member 306 into the cams 310 and causing it to move. The driving force of the motor 308 is transmitted to the front cam 310 via the shaft 311. The photosensor 309 is used to detect the position of the glass moving part 1c by switching between a light-transmitting state and a light-blocking state via a flag 307 provided on the glass moving part 1c.

[0039] The glass moving section 1c comprises two reading glasses 304 corresponding to two reading units 301, a flag 307, and a glass moving member 306 that supports the inner box short axis 303. Each of the two reading glasses 304 has a white reference plate 305 attached to it, which is a white reference member for performing shading correction. The two reading glasses 304 function as transmissive members through which reflected light from the object to be read is transmitted. The glass moving member 306 has the two reading glasses 304 attached to it. During shading correction, the entire glass moving section 1c, including the white reference plate 305, moves to the left (downstream in the conveying direction of the sheet S).

[0040] The two reading glass panels 304 are provided between the corresponding reading unit 301 and the print belt 25 (image forming surface 26), and have a dustproof function to suppress the adhesion of foreign matter to the reading unit 301.

[0041] Figure 5 is an explanatory diagram of the operation of the inline scanner unit 1 during shading correction. During shading correction, the entire glass moving section 1c, including the white reference plate 305, moves from the position shown in Figure 5(a) to the downstream position in the transport direction shown in Figure 5(b). As the entire glass moving section 1c moves, the inner box short axis 303 rides up from the bottom of the step of the glass moving member 306 to the ceiling. As a result, the glass moving section 1c is pushed by the inner box short axis 303 of the inner box 1b and moves toward the image forming surface 26. In other words, the glass moving section 1c moves to the lower left in Figure 5(b).

[0042] The white reference plate 305 is positioned at the same height as the surface of the sheet on the image forming surface 26 in the height direction, as the glass moving part 1c moves toward the image forming surface 26 by the inner box 1b. Since the distance of the inner box 1b from the image forming surface 26 does not change, the distance from the reading unit 301 to the image forming surface 26 also does not change. As a result, the reading unit 301 can read the white reference plate 305 at the same distance as the distance from the reading unit 301 to the surface of the sheet S when reading the sheet S. This enables highly accurate shading correction. During shading correction, the white reference plate 305 moves to the same position as the sheet S when the image of the sheet S is read, and moves to a different position when reading the image of the sheet S.

[0043] Figure 6 is a cross-sectional view of the inline scanner unit 1. This cross-sectional view shows the cross-section when the inline scanner unit 1 is cut in the direction of transport of the sheet S. The reading unit 301 includes light sources 401a and 401b, reflective mirrors 402a, 402b, 402c, 402d, and 402e, an imaging lens 403, a light receiving unit 404, and a sensor substrate 405. The light sources 401a and 401b irradiate the sheet S on the image forming surface 26 with light. The light sources 401a and 401b are composed of multiple light-emitting elements, such as LEDs (Light Emitting Diodes), arranged linearly in a direction intersecting the transport direction. The light receiving unit 404 receives the light reflected by the sheet S from the light sources 401a and 401b. The reflective mirrors 402a to 402e are an optical system that guides the light reflected by the sheet S to the imaging lens 403. The imaging lens 403 forms an image of the reflected light guided by the reflective mirrors 402a to 402e onto the light-receiving surface of the light-receiving unit 404.

[0044] The light-receiving unit 404 outputs a reading result (read image), which is an electrical signal corresponding to the reflected light received on the light-receiving surface. This reading result is an analog signal representing the image read from the sheet S. The light-receiving unit 404 is composed of multiple photoelectric conversion elements, such as a CCD (Charge Coupled Device) sensor, arranged in the same direction as the light-emitting element array. The light-receiving unit 404 is mounted on the sensor board 405. The sensor board 405 is connected to the control board 302 and transmits the reading result (read image), which is an analog signal output from the light-receiving unit 404, to the control board 302. The configuration of the control board 302 will be described later.

[0045] The reading unit 301 reads the image with the direction in which the light-emitting element arrays of the light sources 401a and 401b and the photoelectric conversion element array of the light-receiving unit 404 are aligned as the main scanning direction. The main scanning direction is, for example, the direction that intersects the transport direction of the sheet S. The transport direction of the print belt 25 that intersects the main scanning direction becomes the sub-scanning direction. The reading unit 301 reads the image of the sheet S as it is transported along the transport direction.

[0046] The white reference plate 305, placed on the reading glass 304, is read by the reading unit 301 during shading correction. The light receiving unit 404 has individual differences in the characteristics of each photoelectric conversion element (each pixel). Furthermore, it is not easy to make the light emitted from the light sources 401a and 401b uniform in the main scanning direction. For this reason, even if an image is read from a sheet S in which an image with uniform image density is formed, the resulting image data may have variations depending on the position in the main scanning direction.

[0047] To suppress such variations, shading correction is performed. Specifically, the reading unit 301 reads the white reference plate 305. From the reading result of the white reference plate 305, a correction value is derived such that the reading result (e.g., brightness value) of each pixel in the main scanning direction becomes uniform to a specific value. This correction value corrects the illumination amount of the light sources 401a and 401b, the sensitivity variation of the photoelectric conversion element of the light receiving unit 404, or the reading result of the image on the sheet S, thereby correcting individual differences in the photoelectric conversion element and variations in light intensity.

[0048] As explained in Figure 5, the distance from the reading unit 301 to the white reference plate 305 when reading the white reference plate 305 is the same as the distance from the reading unit 301 to the sheet S when reading the sheet S. The distance from the reading unit 301 to the object to be read (white reference plate 305 or sheet S) is hereinafter referred to as the "reading height". Since the variation in the main scanning direction of the light distribution of the light sources 401a and 401b also differs depending on the reading height, if the reading height differs between shading correction and sheet S reading, proper shading correction may not be performed, potentially leading to a deterioration in the image quality of the read image. In this embodiment, since the reading height is the same between shading correction and sheet S reading, proper shading correction is achieved.

[0049] (Control board) Figure 7 is an explanatory diagram of the control board 302. The control board 302 is electrically connected to the light sources 401a, 401b and the light receiving unit 404 of the reading unit 301. The control board 302 is further electrically connected to the motor 308 and the photosensor 309. As described above, the motor 308 is the drive source for moving the glass moving unit 1c on which the white reference plate 305 is provided. In Figure 7, the inline scanner unit 1 is connected to the print module 2000.

[0050] The control board 302 is an information processing device equipped with a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, and a RAM (Random Access Memory) 503. The CPU 501 controls the operation of the inline scanner unit 1 by executing a computer program stored in the ROM 502, using the RAM 503 as a working area. In addition, the control board 302 includes a lighting control unit 504 for controlling the operation of light sources 401a and 401b, a drive control unit 505 for controlling the operation of the motor 308, an A / D conversion unit 506 for processing the reading results (read images), and an image processing unit 507. The lighting control unit 504, drive control unit 505, A / D conversion unit 506, and image processing unit 507 are connected to the CPU 501. The control board 302 may be implemented using discrete components or a single-chip semiconductor product. Examples of single-chip semiconductor products include MPUs (Micro-Processing Units), ASICs (Application Specific Integrated Circuits), and SOCs (System-On-a-Chip).

[0051] The lighting control unit 504 controls the lighting and extinguishing of the light sources 401a and 401b under the control of the CPU 501. The drive control unit 505 controls the movement of the glass moving unit 1c by transmitting a drive signal to the motor 308 under the control of the CPU 501. Specifically, the drive control unit 505 controls the movement of the glass moving unit 1c to the state shown in Figure 5(a) when reading the sheet S, and controls the movement of the glass moving unit 1c to the state shown in Figure 5(b) when reading the white reference plate 305.

[0052] The A / D conversion unit 506, under the control of the CPU 501, converts the reading result (read image), which is an analog signal output from the light receiving unit 404, into a digital signal and transmits it to the image processing unit 507. The image processing unit 507, under the control of the CPU 501, performs various image processing on the reading result (read image), which is a digital signal acquired from the A / D conversion unit 506, and generates image data representing the image read from the sheet S. The image data is transmitted from the control board 302 to an external device such as a print module 2000 or a personal computer.

[0053] The print module 2000 includes an image analysis unit 2400. The image analysis unit 2400 analyzes image data acquired from the control board 302 and calculates various correction values. The correction values ​​calculated by the image analysis unit 2400 are fed back to the pre-image registration correction unit 2100, the print belt unit 2200, and the recording unit 2300, and are used to adjust geometric characteristics and image density unevenness.

[0054] (Holding the reading glass 304) The holding configuration of the reading glass 304 will now be described. Figure 8 is an explanatory diagram of the glass moving part 1c. Figure 8(a) is an overall perspective view of the glass moving part 1c. Figure 8(b) is a cross-sectional view of the glass moving part 1c shown by the dotted line in Figure 8(a). Figure 8(c) is an enlarged view of the area enclosed by the dotted line in Figure 8(b).

[0055] The reading glass 304, on which the white reference plate 305 is provided, is supported at both ends in the main scanning direction by support members 314. The support members 314 are provided on the glass moving member 306. Both the support members 314 and the glass moving member 306 have surfaces (parallel surfaces 314a and 306a) parallel to the image forming surface 26.

[0056] Both ends of the reading glass 304 in the longitudinal direction (main scanning direction) are supported by the parallel surfaces 314a and 306a of the support member 314. Specifically, the surface of the reading glass 304 facing the image forming surface 26 is supported by the parallel surface 314a of the support member 314, and the surface of the reading glass 304 facing the reading unit 301 is in contact with the parallel surface 306a of the glass moving member 306. In other words, both ends of the reading glass 304 in the longitudinal direction (main scanning direction) are sandwiched between the parallel surface 314a of the support member 314 and the parallel surface 306a of the glass moving member 306. With this configuration, the glass moving member 306 can prevent the reading glass 304 from falling off the glass moving part 1c.

[0057] A paper feed guide 315 is provided on the image forming surface 26 side of the reading glass 304. The paper feed guide 315 is fixed to the support member 314 using a fixing member such as double-sided tape. The sheet S is transported by being attracted to the image forming surface 26 between the paper feed guide 315 and the image forming surface 26.

[0058] As shown in Figure 8(b), the reading glass 304 is adjacent to the paper feed guide 315 via a support member 314. However, as shown in Figure 8(c), the reading glass 304 does not come into contact with the support member 314 in areas other than both ends in the main scanning direction. Therefore, the reading glass 304 is independent of the paper feed guide 315.

[0059] Figure 9 is an explanatory diagram of the holding configuration of the glass moving section 1c. The glass moving section 1c is configured such that glass moving members 306, provided at both ends in the main scanning direction, are held by slide shafts 318 attached to the front plate 316 and the rear plate 317. The front plate 316 and the rear plate 317 constitute the housing of the glass moving section 1c. The housing of the glass moving section 1c is open on the paper feed guide 315 side so that the paper feed guide 315 is exposed.

[0060] The support members 314 and glass moving members 306 are usually made mainly of resin or metal. Therefore, the support members 314 and glass moving members 306 deform slightly due to the influence of the internal temperature. Here, it is assumed that the reading glass 304 is supported at both ends in the short direction by a sheet metal. This sheet metal is positioned along the longitudinal direction of the reading glass 304. However, in a configuration where both ends in the short direction of the reading glass 304 are supported by a sheet metal, the sheet metal deforms into an arc shape due to the influence of the internal temperature. When the sheet metal supporting the reading glass 304 deforms into an arc shape, the reading glass 304 rests on the sheet metal at a point or along a line. This changes the orientation of the reading glass 304 resting on the sheet metal. Experiments have shown that when the length of the sheet metal in the longitudinal direction is 500 [mm], the height of both ends in the longitudinal direction of the reading glass 304 changes by as much as 0.2 [mm]. However, the support member 314 and glass moving member 306 described in this embodiment only support both ends of the reading glass 304 in the main scanning direction. Therefore, even if they deform, the physical impact on the reading glass 304 is minimal. Experiments showed that the height of both ends of the reading glass 304 in the longitudinal direction was less than 0.1 [mm].

[0061] To this end, the distance to the sheet S when the reading unit 301 reads the sheet S and the distance to the white reference plate 305 when the reading unit 301 reads the white reference plate 305 remain the same without changing due to the influence of the support member 314 and the glass moving member 306. As a result, even if the support member 314 and the glass moving member 306 are slightly deformed by heat, shading correction can be performed with high precision. Consequently, the degradation of image quality of the reading result (read image) by the inline scanner unit 1 is suppressed.

[0062] In this embodiment, an example was described in which the inline scanner unit 1 is provided in an inkjet type print module 2000. The inline scanner unit 1 of this embodiment is also effective when provided in other devices such as electrophotographic image forming systems. In any case, the inline scanner unit 1 can be installed in any device as long as it is configured to read the white reference plate 305 at the same position as the sheet S and perform shading correction.

Claims

1. A conveying means for transporting a sheet on which an image has been formed, A reading means for reading the image formed on the sheet being transported by the transport means, A transparent member is provided between the position where the conveying means conveys the sheet and the reading means, A reference member provided in the transparent member and read by the reading means, Support members that support the transparent member at both ends in a direction intersecting the conveying direction of the sheet by the conveying means, When performing shading correction, the support member is moved to move the reference member attached to the transparent member to a first position where the sheet is located when the sheet is read, and when the reading means reads the image formed on the sheet, the support member is moved to move the reference member attached to the transparent member from the first position to another second position, comprising: The reading means is characterized in that, when reading the image formed on the sheet, it reads the sheet that has been transported to the first position by the transport means, and when performing shading correction, it reads the reference member that has been moved to the first position by the moving means. Image reading device.

2. The moving means is characterized in that, when the reading means reads the image formed on the sheet, it moves the support member from the first position in the transport direction, thereby moving the reference member attached to the transparent member to the second position. The image reading device according to claim 1.

3. The conveying means conveys the sheet by adhering it to the surface of the belt, The support member has a first parallel surface parallel to the surface of the belt that adsorbs the sheet, and is characterized in that it supports the permeable member with the first parallel surface. The image reading device according to claim 2.

4. It has a movable member to which the support member is attached, The characteristic is that the reference member attached to the transparent member supported by the support member moves as the moving member is moved by the moving means, The image reading device according to claim 3.

5. The moving member has a second parallel surface parallel to the surface of the belt that adsorbs the sheet, and is characterized by pressing the permeable member with the second parallel surface. The image reading device according to claim 4.

6. The support member is characterized in that a paper guide is provided on the side of the belt that adsorbs the sheet, rather than on the side of the permeable member. The image reading device according to claim 5.

7. A conveying means for transporting sheets, An image forming means for forming an image on the sheet that is transported by the transport means, The system includes an image reading device that reads a sheet on which an image has been formed by the image forming means, The aforementioned image reading device is A reading means for reading the image formed on the sheet being transported by the transport means, When performing shading correction, the reference member read by the reading means, The reading means is provided in the direction for reading the sheet, prevents foreign matter from adhering to the reading means, and includes a transparent member to which the reference member is attached. Support members that support the transparent member at both ends in a direction intersecting the conveying direction of the sheet by the conveying means, When performing the shading correction, the support member is moved to move the reference member attached to the transparent member to a first position where the sheet is located when the sheet is read, and when the reading means reads the image formed on the sheet, the support member is moved to move the reference member attached to the transparent member from the first position to another second position, comprising: The reading means is characterized in that, when reading the image formed on the sheet, it reads the sheet that has been transported to the first position by the transport means, and when performing shading correction, it reads the reference member that has been moved to the first position by the moving means. Image forming system.

8. The moving means is characterized in that, when the reading means reads the image formed on the sheet, it moves the support member from the first position in the transport direction, thereby moving the reference member attached to the transparent member to the second position. The image forming system according to claim 7.

9. The conveying means conveys the sheet by adhering it to the surface of the belt, The support member has a first parallel surface parallel to the surface of the belt that adsorbs the sheet, and is characterized in that it supports the permeable member with the first parallel surface. The image forming system according to claim 7.

10. It has a movable member to which the support member is attached, The characteristic is that the reference member attached to the transparent member supported by the support member moves as the moving member is moved by the moving means, The image forming system according to claim 9.

11. The moving member has a second parallel surface parallel to the surface of the belt that adsorbs the sheet, and is characterized by pressing the permeable member with the second parallel surface. The image forming system according to claim 10.

12. The support member is characterized in that a paper guide is provided on the side of the belt that adsorbs the sheet, rather than on the side of the permeable member. The image forming system according to claim 11.

Images