Image reading device and image forming system

Abstract

This invention provides an image reading device and an image forming system that enable the stable mounting of an adjustment member for adjusting the height of the CIS in the reading unit. [Solution] The system comprises a contact image sensor (CIS) 702 for reading an image of a sheet, a carriage for holding the CIS 702, a height adjustment block 842 that contacts the CIS 702 and adjusts the height of the CIS 702 relative to the carriage, and a fixing mechanism for fixing the height adjustment block 842 to the carriage. The fixing mechanism consists of a bolt 846 and a square nut 848 into which the bolt 846 is screwed.

Description

Technical Field

[0001] The present invention relates to an image reading device and an image forming system that read an image of a sheet.

Background Art

[0002] Conventionally, an image reading device that reads an image of a sheet while conveying the sheet by an image sensor is known. In the image reading device described in Patent Document 1, by arranging a contact image sensor (CIS) offset in the main scanning direction and the sub-scanning direction (staggered arrangement), it is possible to read a reading area wider than the reading area that can be read by one CIS.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a reading unit including a CIS has a configuration including, in addition to the CIS, a holding member that holds the CIS and an adjustment member (adjustment piece) that adjusts the height of the CIS with respect to the holding member. In the assembly manufacturing process of such a reading unit, the adjustment member is screwed to the holding member with a driver. At this time, when screwing using a commonly used hexagonal nut, the hexagonal nut may rotate while biting into the holding member when the driver is tightened, and the adjustment member may not be fixed.

[0005] Therefore, an object of the present invention is to provide an image reading device and an image forming system capable of stably attaching an adjustment member that adjusts the height of a CIS in a reading unit.

Means for Solving the Problems

[0006] One aspect of the present invention is an image reading device comprising: an image sensor for reading an image of a sheet; a holding member for holding the image sensor; an adjustment member that contacts the image sensor and adjusts the height of the image sensor relative to the holding member; and a fixing mechanism for fixing the adjustment member to the holding member, wherein the fixing mechanism is composed of a screw and a square nut into which the screw is screwed. [Effects of the Invention]

[0007] The present invention makes it possible to provide an image reading device and an image forming system that can stably mount an adjustment member for adjusting the height of the CIS in the reading unit. [Brief explanation of the drawing]

[0008] [Figure 1] A partial cross-sectional view of an image forming system. [Figure 2] Block diagram of the image forming apparatus and adjustment unit. [Figure 3] Cross-sectional view of the adjustment unit. [Figure 4] A diagram showing the front and back registration area 700. [Figure 5] Cross-sectional view of the surface reading section. [Figure 6] Cross-sectional view of the surface reading section. [Figure 7] Cross-sectional view of the surface reading area with the CIS moved to the shading correction position. [Figure 8] A perspective view of the CIS as seen from the side of the reading glass. [Figure 9] Perspective view of the shading drive unit. [Figure 10] Side view of the shading drive unit. [Figure 11] Detailed plan and cross-sectional views of the reading unit. [Figure 12] Detailed perspective view of the reading unit. [Figure 13] Diagram and cross-sectional view illustrating the height adjustment mechanism of the reading unit. [Figure 14]Explanatory drawing of the fixing mechanism for the height adjustment command. [Figure 15] Diagram showing the sheet library. [Figure 16] Diagram showing the sheet library editing screen displayed on the operation unit. [Figure 17] Diagram showing the patch image formed on the sheet. [Figure 18] Flowchart of the control operation for transporting the sheet. [Figure 19] Comparative example of the height adjustment mechanism of the reading unit.

Mode for Carrying Out the Invention

[0009] (Image forming system) FIG. 1 is a partial cross-sectional view of an image forming system 100. The image forming system 100 includes an image forming apparatus 101, an operation unit (user interface) 180, an adjustment unit (automatic adjustment device) 200, and a post-processing device (finisher) 600. The image forming apparatus 101 forms an image on a recording medium (hereinafter referred to as a sheet) P. The operation unit 180 is operated by a user to set the image forming conditions in the image forming apparatus 101 and also displays the state of the image forming apparatus 101. The adjustment unit 200 performs front-back alignment for measuring the positional deviation between the image formed on the front surface of the sheet P and the image formed on the back surface by the image forming apparatus 101. The post-processing device 600 discharges the sheet P on which the image is formed to the discharge tray 601 or performs post-processing such as stapling, punching, and sorting.

[0010] (Image forming apparatus) The image forming apparatus 101 is a laser beam printer using an electrophotographic method. The image forming apparatus 101 forms an image on a sheet using an electrophotographic image forming process. Examples of the image forming apparatus 101 include, in addition to a laser beam printer, an electrophotographic copying machine (e.g., a digital copying machine), a color LED printer, an MFP (multifunction peripheral), a facsimile apparatus, and a printing machine. The image forming apparatus 101 is not limited to a color image forming apparatus that forms a color image, and may be a monochrome image forming apparatus that forms a monochrome image. The image forming apparatus 101 is not limited to an electrophotographic image forming apparatus, and may be an inkjet printer, a sublimation printer, or a thermal printer using a heat drying method.

[0011] The image forming apparatus 101 will be described with reference to FIGS. 1 and 2. FIG. 2 is a block diagram of the image forming apparatus 101 and the adjustment unit 200. The image forming apparatus 101 includes a printer controller 103, an engine control unit 312, and an engine unit 140. The printer controller 103 includes a sheet library 900 and an image shape correction unit 320. The printer controller 103 is electrically connected to an operation unit 180, the engine control unit 312, and a communication unit 250 of the adjustment unit 200.

[0012] The engine control unit 312 is electrically connected to a conveyance roller drive motor 311 and a flapper drive unit 141. The flapper drive unit 141 drives flappers 131, 132, 133, and 134. The engine control unit 312 is further electrically connected to a first post-fixing sensor 153, a second post-fixing sensor 163, a reverse sensor 137, and the engine unit 140. The engine control unit 312 controls the engine unit 140 to execute an image forming process (including a sheet feeding process). The engine unit 140 includes a yellow image forming unit 120, a magenta image forming unit 121, a cyan image forming unit 122, and a black image forming unit 123. The engine unit 140 further includes a paper feed cassette 113, an intermediate transfer body 106, a secondary transfer roller 114, a first fixing device 150, and a second fixing device 160.

[0013] The yellow image forming unit 120 forms a yellow (Y) toner image. The magenta image forming unit 121 forms a magenta (M) toner image. The cyan image forming unit 122 forms a cyan (C) toner image. The black image forming unit 123 forms a black (K) toner image. The yellow image forming unit 120, magenta image forming unit 121, cyan image forming unit 122, and black image forming unit 123 have almost the same structure except for the toner color, so the yellow image forming unit 120 will be described below.

[0014] The yellow image forming unit 120 has a rotating photosensitive drum 105. Around the photosensitive drum 105 are a charger 111, a laser scanner 107, a developer 112, and a primary transfer roller 118. The charger 111 uniformly charges the surface of the photosensitive drum 105. The laser scanner 107 has a laser driver (not shown) that turns on / off the laser light emitted from a semiconductor laser 108 according to image data supplied from the printer controller 103. The laser light emitted from the semiconductor laser 108 is deflected in the main scanning direction by a rotating polyhedron mirror (not shown). The laser light deflected in the main scanning direction is guided to the surface of the photosensitive drum 105 by a reflector 109, and the uniformly charged surface of the photosensitive drum 105 is exposed in the main scanning direction. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 105 according to the image data.

[0015] The developer unit 112 develops the electrostatic latent image on the surface of the photosensitive drum 105 with yellow (Y) toner to form a yellow (Y) toner image. The primary transfer roller 118 is subjected to a voltage opposite to that of the toner image, transferring the yellow (Y) toner image on the surface of the photosensitive drum 105 onto the intermediate transfer body 106. Similarly, the magenta (M) toner image, cyan (C) toner image, and black (K) toner image formed by the magenta image forming unit 121, cyan image forming unit 122, and black image forming unit 123 are sequentially transferred onto the intermediate transfer body 106. The yellow (Y), magenta (M), cyan (C), and black (K) toner images are superimposed and transferred onto the intermediate transfer body 106 to form a full-color toner image.

[0016] Meanwhile, the sheets P stored in the feed cassette 113 are transported one by one to the secondary transfer roller 114. The secondary transfer roller 114 presses the sheet P against the intermediate transfer body 106 and simultaneously applies a bias with the opposite polarity to the toner. The secondary transfer roller 114 transfers the toner image on the intermediate transfer body 106 to the sheet P. The photosensitive drum 105 and the developer unit 112 are detachable. A feed timing sensor 116 is positioned in the sheet transport path before the secondary transfer roller 114 to determine the timing of the sheet P's feed. In addition, an image formation start position detection sensor 115 for determining the printing start position when performing image formation and a density sensor 117 for measuring the density of patch images during density control are positioned around the intermediate transfer body 106. When performing density control, the density of each patch image is measured by the density sensor 117.

[0017] The image forming apparatus 101 has a first fuser 150 and a second fuser 160 that heat and pressurize the toner image transferred to the sheet P to fix the toner image to the sheet P. The first fuser 150 includes a fuser roller 151 having a heater inside, a pressure belt 152 that presses the sheet P against the fuser roller 151, and a first post-fixing sensor 153 that detects the completion of fixing. The fuser roller 151 and the pressure belt 152 hold the sheet P, heat and pressurize it to fix the toner image to the sheet P, and also transport the sheet P. The second fuser 160 is located downstream of the first fuser 150 in the transport direction of the sheet P. The second fuser 160 is provided to increase the gloss of the image fixed to the sheet P by the first fuser 150 and to ensure fixation. The second fuser 160 includes a fuser roller 161, a pressure roller 162, and a second post-fixing sensor 163.

[0018] Depending on the type of sheet P, it may not be necessary to use the second fuser 160. In this case, to reduce energy consumption, the sheet P is transported to the transport path 130 without passing through the second fuser 160. The flapper 131 switches the destination of the sheet P between the second fuser 160 and the transport path 130. The flapper 132 switches the destination of the sheet P between the transport path 135 and the discharge path 139. For example, in face-up discharge mode, in order to transport the sheet P with an image formed on the first surface to the discharge path 139, the flapper 132 switches the destination of the sheet P to the discharge path 139. For example, in face-down discharge mode, in order to transport the sheet P with an image formed on the first surface to the transport path 135, the flapper 132 switches the destination of the sheet P to the transport path 135. When the rear end of sheet P passes through flapper 134, the conveying direction of sheet P is reversed, and the destination of sheet P is switched to discharge path 139 by flapper 134.

[0019] For example, in double-sided printing mode, after an adjustment chart (measurement test pattern) is printed on the first side of sheet P, the flapper 132 switches the destination of sheet P to the transport path 135 in order to print the adjustment chart on the second side of sheet P. Sheet P, transported to the transport path 135, is transported to the reversal unit 136. After the rear end of sheet P is detected by the reversal sensor 137 in the reversal unit 136, the transport direction of sheet P is reversed. The flapper 133 switches the destination of sheet P to the transport path 138. This reverses the front and back sides of sheet P. Sheet P is transported from the transport path 138 to the secondary transfer nip between the intermediate transfer body 106 and the secondary transfer roller 114. The adjustment chart is transferred to the second side of the sheet at the secondary transfer nip. Sheet P, with the adjustment chart printed on both sides, is transported from the discharge path 139 to the adjustment unit 200.

[0020] (Adjustment unit) The adjustment unit 200 is positioned downstream of the image forming apparatus 101 in the direction of sheet P transport. Figure 3 is a cross-sectional view of the adjustment unit 200. The adjustment unit 200 includes a through-pass 230, a measurement path (transport path) 231 that is bypassed to the lower side, and a discharge path 232 for discharging the sheet from the through-pass 230 or the measurement path 231 to a post-processing device 600 located downstream of the adjustment unit 200. The measurement path 231 is provided with a front / back registration unit (image reading device) 700, which is a measuring unit that performs front / back registration to read adjustment charts formed on both sides of the sheet P. The adjustment unit 200 has a flapper 221 that switches the transport destination of the sheet P between the through-pass 230 and the measurement path 231.

[0021] If front-to-back registration is not performed by the front-to-back registration unit 700, the flapper 221 waits in a downward position to switch the destination of the sheet P to the through-pass 230. The adjustment unit 200 receives the sheet P from the image forming apparatus 101 and transports the sheet P to the through-pass 230 with the first transport roller 201. The sheet P is transported from the through-pass 230 to the discharge pass 232 with the second transport roller 202 and the third transport roller 203. The sheet P is discharged to the post-processing device 600 with the fourth transport roller 204.

[0022] On the other hand, when front-to-back registration is performed by the front-to-back registration unit 700, the flapper 221 waits in an upward position to switch the destination of the sheet P to the measurement path 231. The adjustment unit 200 receives the sheet P from the image forming apparatus 101 and transports the sheet P to the measurement path 231 with the first transport roller 201. The sheet P is transported to the front-to-back registration unit 700 by transport roller pairs 205, 206, 207, 208, 209 and 210. The front-to-back registration unit 700 reads the adjustment charts formed on both sides of the sheet P while transporting the sheet P with transport roller pairs 211, 212 and 213. The sheet P is transported to the discharge path 232 by transport roller pair 214 and discharged to the post-processing device 600 by the fourth transport roller 204.

[0023] As shown in Figure 2, the adjustment unit 200 includes a communication unit 250, an image processing unit 260, and a control unit (control means) 251. The communication unit 250 is electrically connected to the image processing unit 260 and the control unit 251. The communication unit 250 is electrically connected to the printer controller 103 of the image forming apparatus 101. The adjustment unit 200 further includes a transport motor 252, a transport path sensor 253, a flapper switching motor 240, a backing motor 834, a shading motor 810, a photosensor 816, an image sensor 702, and an image sensor 703. The transport motor 252, transport path sensor 253, flapper switching motor 240, backing motor 834, shading motor 810, photosensor 816, image sensor 702, and image sensor 703 are electrically connected to the control unit 251. The image processing unit 260 is electrically connected to the image sensor 702 and the image sensor 703.

[0024] (Front and back registration area) The structure of the front / back registration unit 700 will be explained using Figure 4. Figure 4 is a diagram of the front / back registration unit 700. The front / back registration unit 700 measures the shape of the sheet P and the shape and positional relationship of the image pattern formed on the sheet P. In order to obtain highly accurate measurement results, it is necessary to average out the shape variations and print position variations of each sheet P, so multiple sheets P are measured. In order to shorten the adjustment time for measuring multiple sheets P, the front / back registration unit 700 measures while transporting the sheets P. Also, since it is desirable for the size of the front / back registration unit 700 to be small, the front / back registration unit 700 uses contact image sensors (CIS) image sensors 702 and 703.

[0025] The front / back registration unit 700 includes a front reading unit 911 for reading the front surface of the sheet P and a back reading unit 912 for reading the back surface of the sheet P. The front reading unit 911 includes a front reading box 901, a reading glass (glass plate) 704 as a transparent member (light-transmitting member), and backing rollers 706 and 707. The back reading unit 912 includes a back reading box 902, a reading glass 704, and backing rollers 706 and 707. The reading glass 704 forms part of the measurement path 231. The front reading box 901 is located on one side of the measurement path 231. The back reading box 902 is located on the other side of the measurement path 231. The front reading box 901 and the back reading box 902 continuously read the front and back surfaces of the sheet P as it is transported in the transport direction CD. Each of the front reading box 901 and the back reading box 902 is provided with multiple image sensors (hereinafter referred to as CIS) 702 and 703 as reading means. Each of the front reading box 901 and the back reading box 902 is positioned facing the measurement path 231 via a reading glass 704. The backing rollers 706 and 707 are positioned on the opposite side of the measurement path 231, facing the reading glass 704.

[0026] The transport roller pairs (transport means) 211, 212, and 213 transport the sheet P in the transport direction CD at a stable transport speed. The transport roller pairs 211, 212, and 213 are driven by the transport motor (drive means) 252. The reading glass 704 functions as a guide member that guides the movement of the sheet P in order to stabilize the position of the sheet P in the depth of field direction of the CIS 702, 703 of the front reading box 901 and the CIS 702, 703 of the back reading box 902. The surfaces of the backing rollers 706 and 707 are black to clarify the contrast with the edges of the sheet P. The backing rollers 706 and 707 are driven by the backing motor 834.

[0027] (Reading section) Since the configuration of the front reading unit 911 is the same as that of the back reading unit 912, the front reading unit 911 will be described below, and the description of the back reading unit 912 will be omitted. Figures 5 and 6 are cross-sectional views of the front reading unit 911. Using Figures 5 and 6, the state in which the sheet P is transported to the front reading unit 911 will be explained. CIS 702 is positioned opposite the backing roller 706 via the reading glass 704. CIS 703 is positioned opposite the backing roller 707 via the reading glass 704. CIS 702 and 703 are supported by a carriage (holding member) 835. CIS 702 and 703 are movable by the carriage 835 in the sub-scanning direction Y along the transport direction CD.

[0028] The sheet P is transported in the transport direction CD by a transport roller pair 211 to the upper surface of the transparent reading glass 704. Multiple reference white plates (multiple reference members) 831 and 832 are arranged on the side surface (first surface) of the reading glass 704 facing the measurement path (transport path) 231. A sheet guide member 830 is placed on the reference white plates 831 and 832. The sheet P is transported on the sheet guide member 830, passing through the reading positions between CIS 702 and backing roller 706 and between CIS 703 and backing roller 707, and is transported by the downstream transport roller pair 212 as shown in Figure 6.

[0029] CIS702 and 703 each emit light from a light-emitting unit 805 having a light source, and focus the reflected light from the sheet P onto a line-shaped light-receiving unit (light-receiving sensor surface) 806 using a rod lens array or the like. The reflected light received by CIS702 and 703 is photoelectrically converted and output as an output signal to the image processing unit 260. The image processing unit 260 generates image data based on the output signals of CIS702 and 703. CIS702 and 703, positioned at the reading position RP, read the image of the sheet P being transported at a constant speed on the reading glass 704 using a sheet-reading method. Based on the output signals of CIS702 and 703, the image processing unit 260 generates a surface measurement pattern image 822 of the sheet P, which will be described later.

[0030] Backing rollers 706 and 707 are driven by a backing motor 834 to rotate in the direction of the arrows in Figures 5 and 6 at a peripheral speed approximately the same as the conveying speed (reading speed) of the sheet P. A gap is set between the backing rollers 706 and 707 and the reading glass 704 to reduce the wobbling (swaying) of the sheet P as it is conveyed to the reading position RP of the CIS 702 and 703. Butt rollers (gap guarantee members) 708 and 709 are positioned at both axial ends of the backing rollers 706 and 707 to contact the reading glass 704 and ensure the gap between the backing rollers 706 and 707 and the reading glass 704. The gap between the backing rollers 706 and 707 and the reading glass 704 is obtained by adding a margin to the thickness of the conveyed sheet P. The gap is set so that even if sheet P moves around, the surface (reading surface) of sheet P remains within the readable range of CIS702 and 703.

[0031] (Shading correction) Shading correction will be explained using Figures 7 and 8. Figure 7 is a cross-sectional view of the surface reading unit 911 with CIS 702 and 703 moved to the shading correction position SH. Figure 8 is a perspective view of CIS 702 and 703 as seen from the side of the reading glass 704. In order to perform shading correction, CIS 702 and 703 are moved by the carriage 835 from the downstream reading position RP (Figure 6) to the upstream shading correction position SH (Figure 7) in the transport direction CD of the sheet P in the sub-scanning direction Y.

[0032] CIS702 and 703 cannot perform uniform image reading due to uneven light intensity in the light-emitting section 805 and uneven sensitivity in the light-receiving section 806. Therefore, shading correction is performed to enable uniform image reading. In shading correction, CIS702 and 703 read the reference white plates 831 and 832 via the reading glass 704. The reading surfaces of the reference white plates 831 and 832 are uniformly color-controlled. CIS702 and 703 output the output signal (image data) as a result of the reading to the image processing unit 260. Based on the output signals of CIS702 and 703 when reading the reference white plates 831 and 832, the image processing unit 260 generates correction values ​​to correct the image data when reading sheet P. The control unit 251 corrects the amount of light emitted by the light-emitting unit 805 that illuminates the sheet P based on a correction value, and corrects the amplification factor (gain) that amplifies the output signal of the light-receiving unit 806 when the sheet P is read based on a correction value. In this way, by adjusting the amount of light emitted by the light-emitting unit 805 and / or the amplification factor (gain) of the light-receiving unit 806 based on the reading results of the reference white plates 831 and 832, the CIS 702 and 703 can read the sheet P uniformly.

[0033] In this embodiment, the shading correction position SH (Figure 7) is located upstream of the reading position RP (Figure 6) in the transport direction CD of the sheet P. Therefore, the reference white plates 831 and 832 are located upstream of the reading position RP in the transport direction CD of the sheet P. The accuracy of shading correction is improved if the reference white plates 831 and 832 are at as close as possible to the height of the sheet P being transported along the measurement path 231 in the depth of field direction of the CIS 702 and 703. Therefore, in this embodiment, the reference white plates 831 and 832 are located on the side (top surface) of the reading glass 704 facing the measurement path 231.

[0034] If the reference white plates 831 and 832 were positioned on the upper surface of the reading glass 704 downstream of the reading position RP (Figure 6) in the transport direction CD of the sheet P, the leading edge of the sheet P, which is restricted in the depth of field direction by the backing rollers 706 and 707 and has passed the reading position RP, would get caught on the reference white plates 831 and 832, causing a jam. If the reference white plates 831 and 832 were positioned on the lower surface (back side) of the reading glass 704 to prevent jamming, the accuracy of shading correction would decrease. Therefore, in this embodiment, as described above, the reference white plates 831 and 832 are positioned on the surface (upper surface) of the reading glass 704 on the measurement path 231 side, upstream of the reading position RP (Figure 6) in the transport direction CD of the sheet P.

[0035] The reference white plates 831 and 832 may be formed on the side (top surface) of the reading glass 704 facing the measurement path 231 by printing or painting. Alternatively, the reference white plates 831 and 832 may be attached to the side (top surface) of the reading glass 704 facing the measurement path 231 by adhesive or double-sided tape. The reference white plates 831 and 832 are provided so that the side with a uniformly color-controlled reference white surface faces the surface of the reading glass 704. The reference white plates 831 and 832 are expensive and should be handled carefully to prevent scratches, dust, etc. from adhering to them.

[0036] As shown in Figure 8, CIS702 and CIS703 are positioned offset (staggered) in the main scanning direction X (width direction) and the sub-scanning direction Y (transport direction CD). By positioning the two CIS702 and 703 offset in the main scanning direction X so that they partially overlap, a reading area wider than that that can be read by a single CIS702 can be read. In this embodiment, by positioning the two CIS702 and 703 offset in the main scanning direction X so that they partially overlap, a reading area wider than the width of the sheet P in the main scanning direction X can be read. CIS702 and 703 read the black areas of the backing rollers 706 and 707, which are the background, along with the image of the sheet P. This increases the contrast between the edge of the sheet P in the main scanning direction and the black areas, allowing the edge of the sheet P to be detected. This improves the accuracy of front-to-back registration.

[0037] Furthermore, similar to CIS702 and 703, the reference white plates 831 and 832 are also arranged in a staggered pattern, offset from the main scanning direction X and the sub-scanning direction Y, as shown in Figure 8. This reduces the area of ​​the reference white plates 831 and 832, thereby reducing costs. In addition, a sheet guide member (guide sheet) 830 is positioned to cover the reference white plates 831 and 832. The sheet guide member 830 is bonded to the reference white plates 831 and 832, covering their entire surfaces to prevent the leading edge of the conveyed sheet P from getting caught on them. As a result, jamming can be suppressed. The staggered arrangement of the reference white plates 831 and 832 is positioned on the upper surface of the reading glass 704 on the upstream side of the conveying direction CD, and is covered by the sheet guide member 830, thus preventing the leading edge of the sheet from contacting the reference white plates. In other words, jams caused by the white reference plates installed in the transport path can be suppressed. Furthermore, the reference white plates 831 and 832 will not become dirty, and a decrease in reading accuracy will be suppressed.

[0038] The sheet guide member 830 may be attached to the reading glass 704 so as to smoothly connect with the transport guide member 833, which forms part of the measurement path 231 between the transport roller pair 211 located upstream of the reading glass 704 and the reading glass 704. The upstream end of the sheet guide member 830 in the transport direction CD may be provided on the upper surface of the transport guide member 833.

[0039] (Shading drive unit) The shading drive unit will be explained using Figures 9 and 10. Figure 9 is a perspective view of the shading drive unit. Figure 10 is a side view of the shading drive unit. The shading drive unit includes a shading motor 810, a motor gear 811, a gear pulley 812, a timing belt 813, an idler pulley 814, and a slide guide shaft 815. The shading drive unit further includes a photosensor 816, a sensor flag 817, a belt holder 818, and a carriage 835.

[0040] The carriage 835 holds CIS 702 and 703. The slide guide shaft 815 extends in the sub-scanning direction Y, which is parallel to the transport direction CD of the sheet P. The slide guide shaft 815 supports the carriage 835 so that it can slide in the sub-scanning direction Y. The carriage 835 is provided with a belt holder 818. The belt holder 818 holds a portion of the timing belt 813 and is fixed to the timing belt 813. The timing belt 813 is wrapped around the pulley of the gear pulley 812 and the idler pulley 814. The idler pulley 814 tensions the timing belt 813. The gear of the gear pulley 812 meshes with the motor gear 811 of the shading motor 810, which is the drive source. The driving force of the shading motor 810 is transmitted to the timing belt 813 via the motor gear 811 and the gear pulley 812.

[0041] The rotation of the shading motor 810 moves the carriage 835 in the sub-scanning direction Y via the timing belt 813. The carriage 835 is equipped with a sensor flag 817. The photosensor 816 detects the transmission and blocking of light by the sensor flag 817 as the carriage 835 moves. Based on the detection timing of the sensor flag 817 by the photosensor 816, the home position and stop position of the carriage 835 are controlled. By controlling the shading motor 810 based on the detection result of the photosensor 816, the CIS 702 and 703 can be moved back and forth between the reading position RP and the shading correction position SH.

[0042] The surface reading unit 911 can continuously read the sheet P discharged from the image forming apparatus 101. In the electrophotographic image forming apparatus 101, the sheet P is transported by numerous rollers from the feed cassette 113 to the discharge passage 139, so static electricity may accumulate on the sheet P.

[0043] In this embodiment, the sheet guide member 830 is made of a conductive material, such as a stainless steel sheet, and is grounded to suppress the frictional static electricity generated by friction with the sheet P being transported. The sheet guide member 830 is held in the surface reading box 901 together with the reading glass 704 by the holding part 740 described below and is grounded.

[0044] (Reading unit) Figure 11 is a detailed plan view of the reading unit 800, showing a cross-sectional view of the sensor part of the CIS 702 (AA) and a cross-sectional view of the height adjustment block 842 (BB). The reading unit 800 includes the aforementioned CIS 702 and 703, carriage 835, height adjustment blocks 842 and 843 (adjustment members), height fixing blocks 840 and 841, etc. Figure 12 is a perspective view of the reading unit 800. As shown, the height adjustment blocks 842 and 843 and the height fixing blocks 840 and 841 are fitted into both ends of the CIS 702 and 703. The height fixing block 840 abuts against the back surface of the reading glass 704, and the height adjustment block 842 is clamped and fixed by a bolt 846 (screw) and nut 848 via a block fixing rib 844, which is part of the reading unit 800. Furthermore, unlike the height-fixing frames 840 and 841, the height adjustment frame 842 is fixed at a distance from the back surface of the glass 704 without contacting it. The height adjustment frames 842 and 843 are components that contact the CIS 702 to adjust the height of the CIS 702 relative to the carriage 835. The height-fixing frames 840 and 841 and the height adjustment frames 842 and 843 maintain a highly accurate distance between the CIS 702 and 703 and the reading glass surface. Since the height-fixing frames 840 and 841 are outside the main scanning direction readable area of ​​the CIS 702 and 703, contact with the back surface of the glass 704 does not adversely affect the image.

[0045] On the other hand, the height adjustment frames 842 and 843 are positioned in the readable area of ​​the adjacent CIS, for example, height adjustment frame 842 in the case of CIS 703. If they come into contact with the glass 704, they will read streaky images caused by the trajectory of dust and other debris during shading movement, preventing proper shading correction. For this reason, they are fixed in a position away from the glass 704. However, because it is necessary to accurately guarantee the distance between the CIS, which has a narrow readable depth, and the glass surface, they are designed to be adjustable and equipped with a mechanism to accurately adjust and fix their position during assembly and manufacturing in order to cancel out variations in the multiple related parts.

[0046] As shown in Figures 11 and 13, the reading unit 800 has a compression spring 851, which biases the CIS 702 toward the glass 704 by the spring reaction force, allowing the height-fixing block 840 to constantly contact the glass 704. Similarly, the compression spring 850 also biases the CIS 702 toward the glass 704, restricting the position of the CIS 702 to the overhang portion 854 of the fixed height-adjusting block 842. The compression springs 850 and 851 are examples of elastic members.

[0047] As shown in cross-sectional view CC in Figure 13, the height adjustment block 842 is guided to move vertically by the block fixing rib 844 and is clamped and fixed by a bolt 846 and a nut 848. The bolt 846 and nut 848 constitute a fixing mechanism for fixing the height adjustment block 842. When assembling the height adjustment block 842, a tool (not shown) is used to temporarily hold the height adjustment block 842 in the correct position. The tool is equipped with a retaining member with a gauge that holds the overhang portion 854 at a predetermined height. The worker uses a screwdriver or the like to screw the bolt 846 onto the nut 848.

[0048] A key feature of this invention is that when tightening the bolt 846, the rotational force due to the tightening torque is not transmitted to the height adjustment block 842 because it is via the block fixing rib 844. Furthermore, since the adjustment hole 849 is larger than the bolt 846, the movement of the bolt 846 is not transmitted to the height adjustment block 842. As a result, the position of the height adjustment block 842, which is temporarily held in the correct position, does not change, enabling precise and fine-tuning during assembly.

[0049] In Figure 14 (viewpoint D of Figure 13), the nut 848 is square in shape, and its rotation is restricted by the two walls of the restricting rib 852, preventing the nut 848 from rotating along with the bolt 846 when it is tightened. A distinctive feature is the use of a nut with a small number of sides in its external shape.

[0050] Figure 19 shows a fixing mechanism when a hexagonal nut 870 is used to fix the height adjustment block 842, as a comparative example. The outer circumference circle 873 of the rotation trajectory of the hexagonal nut 870 is smaller than the outer circumference circle 853 of the rotation trajectory of the square nut 848, making it more likely to bite into the wall.

[0051] On the other hand, the outer circumference circle 853 of the rotation trajectory of the square nut 848 is larger than the outer circumference circle 873 of the rotation trajectory of the hexagonal nut 870, making it less likely to dig into the wall. The square nut 848 prevents the bolt 846 from rotating along with it, ensuring secure tightening. At the same time, as shown in Figure 12, the regulating rib 852 and the nut fixing rib 844 are resin parts molded integrally with the reading unit 800, and the simple configuration in which the height adjustment nut 842, bolt 846 and nut 848 fit into the pocket shape allows for easy, reliable, and highly accurate adjustment and assembly while keeping costs down.

[0052] (Feedback configuration based on front and back) The measurement by the front / back registration unit 700 and the feedback destination of the measurement results will be explained. Figure 15 shows the sheet library 900. As shown in Figure 15, a first geometric adjustment value 921 for the front surface and a second geometric adjustment value 922 for the back surface are set corresponding to the sheet type 910. Figure 16 shows the sheet library editing screen 1001 displayed on the operation unit 180. The user can select and set the sheet type 910 from the sheet library editing screen 1001. When the image forming apparatus 101 receives a request from the print position adjustment 1002 in the sheet library editing screen 1001 shown in Figure 16, based on the user's operation of the operation unit 180, it forms a patch image 820 (Figure 17) on the sheet P as an adjustment chart.

[0053] Figure 17 shows a patch image 820 formed on sheet P. The front / back registration unit 700 reads the surface of sheet P on which the patch image 820, which serves as an adjustment chart, is formed, using the CIS 702 and 703 of the front reading box 901, while sheet P is being transported by transport roller pairs 211, 212, and 213. The CIS 702 and 703 continuously read the surface of sheet P, and the image data is synthesized by stitching together the read line images, and measurements are taken from the synthesized image. Similarly, the CIS 702 and 703 of the back reading box 902 read the back surface of sheet P as it is transported by transport roller pairs 211, 212, and 213.

[0054] Figure 17(a) shows a surface measurement pattern image 822 obtained by reading the surface of sheet P on which patch images 820 are formed by CIS 702 and 703 of the surface reading box 901. The four patch images 820 are formed in the four corner regions of the surface measurement pattern image 822. The surface measurement pattern image 822 includes the leading edge 822a and trailing edge 822b of sheet P in the transport direction CD, and the left edge 822c and right edge 822d along the transport direction CD. The transport direction CD of sheet P is defined as the sub-scanning direction Y, and the direction perpendicular to the sub-scanning direction Y is defined as the main scanning direction X.

[0055] The image processing unit 260 calculates the detection coordinates (X01, Y01), (X11, Y11), (X21, Y21), and (X31, Y31) of the sheet P from the surface measurement pattern image 822. The image processing unit 260 calculates the detection coordinates (X41, Y41), (X51, Y51), (X61, Y61), and (X71, Y71) of the patch image 820 from the surface measurement pattern image 822. Based on the detection coordinates (X01, Y01) to (X71, Y71), the image processing unit 260 measures the amount of distortion of the surface image and the amount of positional displacement between the sheet P and the image. Based on the amount of distortion and positional displacement of the surface image, the image processing unit 260 calculates a first geometric adjustment value 921 (Figure 15) that allows the image shape correction unit 320 to issue a shape correction instruction. The first geometric adjustment value 921 includes lead position, side position, main scan magnification, sub scan magnification, perpendicularity, and rotation amount.

[0056] Figure 17(b) shows a back surface measurement pattern image 823 obtained by reading the back surface of a sheet P on which patch images 820 are formed by CIS 702 and 703 of the back surface reading box 902. The four patch images 820 are formed in the four corner regions of the back surface measurement pattern image 823. The back surface measurement pattern image 823 includes the leading edge 823a and trailing edge 823b of the sheet P in the transport direction CD, and the left edge 823c and right edge 823d along the transport direction CD.

[0057] The image processing unit 260 calculates the detected coordinates (X02, Y02), (X12, Y12), (X22, Y22), and (X32, Y32) of the sheet P from the back surface measurement pattern image 823. The image processing unit 260 calculates the detected coordinates (X42, Y42), (X52, Y52), (X62, Y62), and (X72, Y72) of the patch image 820 from the back surface measurement pattern image 823. Based on the detected coordinates (X02, Y02) to (X72, Y72), the image processing unit 260 measures the amount of distortion of the back surface image and the amount of positional displacement between the sheet P and the image. Based on the amount of distortion and positional displacement of the back surface image, the image processing unit 260 calculates a second geometric adjustment value 922 (Figure 15) that allows the image shape correction unit 320 to issue shape correction instructions. The second geometric adjustment value 922 includes lead position, side position, main scan magnification, sub scan magnification, perpendicularity, and rotation amount.

[0058] The first geometric adjustment value 921 and the second geometric adjustment value 922 calculated by the image processing unit 260 are transmitted to the sheet library 900 in the image forming apparatus 101 via the communication unit 250. The first geometric adjustment value 921 and the second geometric adjustment value 922 are stored in the sheet library 900 as front-side parameters and back-side parameters. In this way, setting values ​​are stored in the sheet library 900 for each sheet type 910. By reading the setting values ​​from the sheet library 900 according to the sheet type 910 on which the print job is executed and correcting the image position and image distortion, it becomes possible to output a print image with highly accurate front-side and back-side printing positions. Here, the front measurement pattern image 822 and back-side measurement pattern image 823 exemplified in this description may be measured before the execution of the print job, or they may be automatically measured at a predetermined timing as calibration during the execution of the print job.

[0059] (Control operation) The control operation for transporting the sheet P in the image forming apparatus 101 and the adjustment unit 200 will be explained below using Figure 18. Figure 18 is a flowchart of the control operation for transporting the sheet P. The control unit 251 executes the control operation according to a program stored in internal memory (not shown). When a job is submitted by the user from the operation unit 180, the control unit 251 starts the control operation. The control unit 251 determines whether the job is a normal print job or not (S1101). If the job is a normal print job (YES in S1101), the control unit 251 has each component of the image forming apparatus 101 and the adjustment unit 200 wait in the home position (HP) (S1102). At this time, in order to guide the sheet P to the through-pass 230 within the adjustment unit 200, the control unit 251 has the flapper 221 waiting facing downward (through-pass position) (S1102).

[0060] The image forming apparatus 101 forms an image on the sheet P (S1103). The adjustment unit 200 receives the sheet P with the image formed on it from the image forming apparatus 101 (S1104). The control unit 251 controls the transport motor 252 to discharge the sheet P to the post-processing device 600 through the through-pass 230 using the first transport roller 201, the second transport roller 202, the third transport roller 203, and the fourth transport roller 204 (S1105). The control unit 251 determines whether the sheet P is the final sheet (S1106). If the sheet P is not the final sheet (NO in S1106), the control unit 251 returns the process to S1101. If the sheet P is the final sheet (YES in S1106), the control unit 251 terminates the control operation.

[0061] On the other hand, when the user selects a sheet type 910 from the sheet library 900 and selects print position adjustment 1002 using the operation unit 180, a front-to-back registration job is submitted. If the job is a front-to-back registration job (NO in S1101), the control unit 251 has each component of the image forming apparatus 101 and adjustment unit 200 stand by in the home position (HP) (S1107). At this time, in order to guide the sheet P to the measurement path 231 within the adjustment unit 200, the control unit 251 has the flapper 221 stand by facing upward (position for measurement path) (S1107).

[0062] The image forming apparatus 101 forms patch images 820 as adjustment charts on both sides of the sheet P (S1108). Before reading both sides of the sheet P, the control unit 251 moves CIS 702 and 703 to the shading correction position SH and performs shading correction (S1109). The control unit 251 moves CIS 702 and 703 to the reading position RP (S1110). The adjustment unit 200 receives the sheet P on which the patch images 820 have been formed (S1111). The sheet P transported to the adjustment unit 200 is transported to the measurement path 231 by the flapper 221 (S1112). The sheet P is transported to the front / back registration section 700 by transport roller pairs 205, 206, 207, 208, 209 and 210.

[0063] The control unit 251 reads the patch image 820 formed on both sides of the sheet P and the sheet P itself using the CIS 702 and 703 of the front reading box 901 and the back reading box 902, respectively (S1113). The image processing unit 260 obtains a front measurement pattern image 822 and a back measurement pattern image 823 from the reading results of the CIS 702 and 703. High-resolution line image synthesis is performed in the front / back registration unit 700 to measure the misalignment of the print position of the patch image 820 on the sheet P and the shape of the sheet P. The image processing unit 260 calculates a first geometric adjustment value 921 and a second geometric adjustment value 922 from the front measurement pattern image 822 and the back measurement pattern image 823. The image processing unit 260 saves the first geometric adjustment value 921 and the second geometric adjustment value 922 in the sheet library 900 of the image forming apparatus 101 via the communication unit 250 (S1114). This completes the adjustment of the print position for front-to-back registration.

[0064] The sheet P, having passed through the front / back registration section 700, is transported to the through-pass 230 by the transport roller pair 214 (S1115). Subsequently, the sheet P is transported to the discharge pass 232 by the third transport roller 203 and discharged to the post-processing device 600 by the fourth transport roller 204 (S1105). The control unit 251 determines whether the sheet P is the final sheet (S1106), and if the sheet P is the final sheet (YES in S1106), the control unit 251 terminates its control operation. [Explanation of Symbols]

[0065] 231 measurement paths 700 Front and back registration area 702, 703 CIS 835 Carriage 842, 843 Height adjustment piece 846 volts 848 Nut

Claims

1. An image sensor that reads the image of the sheet, A holding member for holding the image sensor, An adjustment member that contacts the image sensor and adjusts the height of the image sensor relative to the holding member, A fixing mechanism for fixing the adjustment member to the holding member, Equipped with, The aforementioned fixing mechanism is composed of a screw and a square nut into which the screw is screwed. An image reading device characterized by the following.

2. The retaining member has two wall portions arranged to sandwich the square nut, The aforementioned square nut is in contact with the two walls, thereby restricting its rotation. The image reading device according to feature 1.

3. The adjustment member is provided with an elastic member that biases the adjustment member, The image reading device according to feature 1.

4. An image forming apparatus that forms an image on a sheet, The image reading device comprises the image reading device according to any one of claims 1 to 3, An image forming system characterized by the following features.

Images