Image forming system and image reading device

Abstract

To suppress reduction in image reading accuracy and an occurrence of jamming.SOLUTION: An image forming system 100 includes: first control means 312 configured to control geometric characteristics of an image formed on a recording medium P of an image forming unit 101 on the basis of an image read by a reading means 702; changing means 707 configured to change a gap size between a transparent member and a reference member in a reading position; and second control means 251 configured to control the changing means so that the gap size becomes a first size when a thickness of the recording medium conveyed by a conveyance means 211 is a first thickness, and to control the changing means so that the gap size becomes a second size larger than the first size when the thickness of the recording medium conveyed by the conveyance means is a second thickness thicker than the first thickness.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image forming system. and image reading device Regarding. [Background technology]

[0002] Conventionally, there is known a reading device that reads an image of a sheet by an image sensor while the sheet is being conveyed. Patent Document 1 discloses a reading device that reads an image of a sheet being conveyed through a contact glass that forms a conveying path along which the sheet is conveyed. A backing member (reference member) that serves as a reading reference is disposed on the opposite side of the conveying path from the contact glass. The backing member forms a part of the conveying path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-268058 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the backing member constitutes a part of the transport path, the following problems may occur. Specifically, for example, when a gap between the backing member and the contact glass is set so that a relatively thick sheet such as cardboard can be transported, if thin paper is transported, the thin paper may not be accommodated within the focal range of the image sensor. This results in a decrease in reading accuracy. On the other hand, for example, when a gap between the backing member and the contact glass is set based on the thickness of the thin paper, if thick paper is transported, the thick paper cannot pass between the backing member and the contact glass, and a jam occurs.

[0005] In view of the above problems, an object of the present invention is to prevent the occurrence of jams while suppressing a decrease in image reading accuracy. [Means for solving the problem]

[0006] An image forming system according to an embodiment of the present invention comprises: an image forming section for forming an image on a first sheet; a conveying means for conveying the first sheet on which an image has been formed by the image forming unit; A transparent member; a reading means having a reading sensor that reads an image on the first sheet being conveyed by the conveying means through the transparent member at a reading position in a conveying direction in which the first sheet is conveyed; an opposing member that is provided at the reading position in the transport direction and is provided on an opposite side of the transparent member from the reading means, the opposing member being disposed such that the first sheet being transported by the transport means passes through a gap between the opposing member and the transparent member; Change the size of the gap Eccentric Cam and, A control means; Equipped with The eccentric cam is capable of stopping at at least a first position, a second position, a third position, and a fourth position; a rotation angle between the first position and the second position is a first angle, a rotation angle between the second position and the third position is a second angle, a rotation angle between the third position and the fourth position is a third angle, and a rotation angle between the fourth position and the first position is a fourth angle, and the first angle to the fourth angle are each equal to one another; The control means a control unit for controlling a geometric characteristic of an image formed on a second sheet by the image forming unit based on the image read by the reading unit, and the image forming unit forms an image on the second sheet based on the geometric characteristic controlled by the control unit; Obtaining information regarding a thickness of the first sheet; When the thickness of the first sheet is a first thickness, the size of the gap is set to a first size. Eccentric Cam of To stop at the first position and controlling the gap so that, when the thickness of the first sheet is a second thickness that is thicker than the first thickness, the size of the gap becomes a second size that is larger than the first size. Eccentric Cam of To stop at the third position control death, the first size gap is the smallest gap and the second size gap is the largest gap; The first position and the third position of the eccentric cam are positions that are opposed to each other by 180 degrees. It is characterized by: Effect of the Invention

[0007] According to the present invention, it is possible to suppress the occurrence of jams while suppressing a decrease in image reading accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. [Diagram 2] FIG. 2 is a block diagram of an image forming apparatus and an adjustment unit. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. 2 is a cross-sectional view of the back side CIS taken along the transport direction. [Figure 6] FIG. 4 is a cross-sectional view of the backing roller as viewed along the conveying direction. [Figure 7] FIG. 13 is an explanatory diagram of reading a thin sheet. [Figure 8] FIG. 13 is an explanatory diagram of reading a thin sheet. [Figure 9] FIG. 13 is an explanatory diagram of reading a thick sheet. [Figure 10] FIG. 13 is an explanatory diagram of reading a thick sheet. [Figure 11] FIG. [Figure 12] 13A and 13B are diagrams showing modified examples of the abutting member. [Figure 13] FIG. 13 is a diagram showing a gap switching table for abutting members according to a modified example. [Figure 14] A diagram showing the Sheets library. [Figure 15] FIG. 4 is a diagram showing a sheet library editing screen displayed on the operation unit. [Figure 16] 4A and 4B are diagrams showing patch images formed on a sheet. [Figure 17] 11 is a flow chart of a control operation for conveying a sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 (image forming section) 101, an operation section (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 section 180 is operated by a user to set conditions for image formation in the image forming apparatus 101, and displays the state of the image forming apparatus 101 on a display section. The adjustment unit 200 performs front-back registration to adjust the positional deviation between an image formed on the front side of the sheet P by the image forming apparatus 101 and an image formed on the back side. The post-processing device 600 discharges the sheet P on which the image has been formed to a discharge tray 601, and performs post-processing such as stapling, punching, and sorting.

[0010] (Image forming device) The image forming apparatus 101 is an electrophotographic laser beam printer. The image forming apparatus 101 forms an image on a sheet using an electrophotographic image forming process. In addition to a laser beam printer, the image forming apparatus 101 may be, for example, an electrophotographic copying machine (e.g., a digital copying machine), a color LED printer, an MFP (multifunction machine), a facsimile machine, or a printing machine. The image forming apparatus 101 is not limited to a color image forming apparatus that forms a color image, but may also 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, but may also be an inkjet printer, a dye-sublimation printer, or a thermal printer using a thermal 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 the operation unit 180, the engine control unit 312, and a communication unit 250 of the adjustment unit 200. The engine control unit 312 is electrically connected to a conveying roller drive motor 311 and a flapper drive unit 141 that drives the 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, an inversion 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 has 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 has a feed cassette 113, an intermediate transfer body 106, a secondary transfer roller 114, a first fixing unit 150, and a second fixing unit 160.

[0012] 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, the magenta image forming unit 121, the cyan image forming unit 122, and the black image forming unit 123 have almost the same structure except for the color of the toner, so the yellow image forming unit 120 will be described below.

[0013] The yellow image forming unit 120 has a rotating photosensitive drum 105. Around the photosensitive drum 105, a charger 111, a laser scanner 107, a developing unit 112, and a primary transfer roller 118 are arranged. 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 a laser beam emitted from a semiconductor laser 108 according to image data supplied from the printer controller 103. The laser beam emitted from the semiconductor laser 108 is deflected in the main scanning direction by a rotating polygon mirror (not shown). The laser beam deflected in the main scanning direction is guided to the surface of the photosensitive drum 105 by a reflecting mirror 109, and exposes the uniformly charged surface of the photosensitive drum 105 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.

[0014] The developing device 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. A voltage of the opposite polarity to that of the toner image is applied to the primary transfer roller 118, which transfers the yellow (Y) toner image on the surface of the photosensitive drum 105 onto the intermediate transfer body 106. Similarly, a magenta (M) toner image, a cyan (C) toner image, and a black (K) toner image formed by a magenta image forming unit 121, a cyan image forming unit 122, and a 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 transferred onto the intermediate transfer body 106 in a superimposed manner to form a full-color toner image.

[0015] Meanwhile, the sheets P stored in the feeding cassette 113 are conveyed 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 of 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 developing device 112 are detachable. A feeding timing sensor 116 for timing the feeding of the sheet P is disposed in the sheet conveying path in front of the secondary transfer roller 114. In addition, an image formation start position detection sensor 115 for determining the print start position when forming an image and a density sensor 117 for measuring the density of a patch image during density control are disposed around the intermediate transfer body 106. When performing density control, the density sensor 117 measures the density of each patch image.

[0016] The image forming apparatus 101 has a first fixing device 150 and a second fixing device 160 that heat and pressurize the toner image transferred to the sheet P to fix the toner image to the sheet P. The first fixing device 150 includes a fixing roller 151 having an internal heater, a pressure belt 152 that presses the sheet P against the fixing roller 151, and a first post-fixing sensor 153 that detects the completion of fixing. The fixing roller 151 and the pressure belt 152 hold the sheet P between them and heat and pressurize it to fix the toner image to the sheet P, while conveying the sheet P. The second fixing device 160 is disposed downstream of the first fixing device 150 in the conveying direction of the sheet P. The second fixing device 160 is provided to increase the gloss of the image fixed to the sheet P by the first fixing device 150 and ensure fixability. The second fixing device 160 includes a fixing roller 161, a pressure roller 162, and a second post-fixing sensor 163.

[0017] Depending on the type of sheet P, it may not be necessary to use the second fixing device 160. In this case, in order to reduce energy consumption, the sheet P is conveyed to the conveying path 130 without passing through the second fixing device 160. The flapper 131 switches the conveying destination of the sheet P between the second fixing device 160 and the conveying path 130. The flapper 132 switches the conveying destination of the sheet P between the conveying path 135 and the discharge path 139. For example, in the face-up discharge mode, the flapper 132 switches the conveying destination of the sheet P to the discharge path 139 in order to convey the sheet P having an image formed on its first side to the discharge path 139. For example, in the face-down discharge mode, the flapper 132 switches the conveying destination of the sheet P to the conveying path 135 in order to convey the sheet P having an image formed on its first side to the conveying path 135. When the rear end of the sheet P passes the flapper 134 , the conveying direction of the sheet P is reversed, and the conveying destination of the sheet P is switched to a discharge path 139 by the flapper 134 .

[0018] For example, in the double-sided printing mode, in order to print an adjustment chart on the second side of the sheet P after the adjustment chart is printed on the first side of the sheet P, the flapper 132 switches the destination of the sheet P to the conveying path 135. The sheet P conveyed to the conveying path 135 is conveyed to the inversion section 136. After the rear end of the sheet P conveyed to the inversion section 136 is detected by the inversion sensor 137, the conveying direction of the sheet P is reversed. The flapper 133 switches the destination of the sheet P to the conveying path 138. This inverts the front and back of the sheet P. The sheet P is conveyed from the conveying 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. The sheet P with the adjustment charts printed on both sides is conveyed from the discharge path 139 to the adjustment unit 200.

[0019] (Adjustment unit) The adjustment unit 200 is disposed downstream of the image forming apparatus 101 in the conveying direction of the sheet P. FIG. 3 is a cross-sectional view of the adjustment unit 200. The adjustment unit 200 has a through path 230, a measurement path 231 bypassed to the lower side, and a discharge path 232 for discharging the sheet from the through path 230 or the measurement path 231 to a post-processing apparatus 600 disposed downstream of the adjustment unit 200. The measurement path 231 is provided with a front-back registration unit (image reading device) 700 as a measurement unit that performs front-back registration by reading adjustment charts formed on both sides of the sheet P. The adjustment unit 200 has a flapper 221 that switches the conveying destination of the sheet P between the through path 230 and the measurement path 231.

[0020] When front and back registration is not performed by the front and back registration section 700, the flapper 221 waits in a downward position to switch the destination of the sheet P to the through path 230. The adjustment unit 200 receives the sheet P from the image forming apparatus 101, and conveys the sheet P to the through path 230 by the first conveyance roller 201. The sheet P is conveyed from the through path 230 to the discharge path 232 by the second conveyance roller 202 and the third conveyance roller 203. The sheet P is discharged to the post-processing device 600 by the fourth conveyance roller 204.

[0021] On the other hand, when the front and back registration is performed by the front and back registration section 700, the flapper 221 waits in an upward position to switch the conveyance 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 conveys the sheet P to the measurement path 231 by the first conveyance roller 201. The sheet P is conveyed to the front and back registration section 700 by conveyance roller pairs 205, 206, 207, 208, 209, and 210. The front and back registration section 700 reads the adjustment charts formed on both sides of the sheet P while conveying the sheet P by the conveyance roller pairs 211, 212, and 213 as conveyance means. The sheet P is conveyed to the discharge path 232 by the conveyance roller pair 214, and discharged to the post-processing device 600 by the fourth conveyance roller 204.

[0022] As shown in FIG. 2, the adjustment unit 200 has 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 has a conveying motor 252, a conveying path sensor 253, a flapper switching motor 240, a backing motor 801, a gap switching motor 802, a gap switching sensor 803, an image sensor 701, and an image sensor 702. The conveying motor 252, the conveying path sensor 253, the flapper switching motor 240, the backing motor 801, the gap switching motor 802, the gap switching sensor 803, the image sensor 701, and the image sensor 702 are electrically connected to the control unit 251. The image processing unit 260 is electrically connected to the image sensor 701 and the image sensor 702 as a reading means. The engine control unit (first control means) 312 controls the geometric characteristics of an image formed on a recording medium by the image forming apparatus 101 based on the images read by the image sensors 701 and 702.

[0023] (Front and back registration section) The structure of the front and back register unit 700 will be described with reference to FIG. 4. FIG. 4 is a diagram showing the front and back register unit 700. The front and back register unit 700 measures the shape and positional relationship of the sheet shape and the image pattern printed on the sheet. To obtain highly accurate measurement results, it is necessary to average out the shape variations and print position variations for each sheet, so multiple sheets are measured. In order to shorten the adjustment time for measuring multiple sheets, the front and back register unit 700 performs measurements while conveying the sheets. In addition, it is desirable for the size of the front and back register unit 700 to be as small as possible, so the front and back register unit 700 uses image sensors 701 and 702, which are contact image sensors (CIS).

[0024] An image sensor (hereinafter referred to as a CIS for the front side) 701 as a reading means reads the front side of a sheet. An image sensor (hereinafter referred to as a CIS for the back side) 702 as a reading means reads the back side of a sheet. The CIS for the front side 701 is disposed on one side of the measurement path 231. The CIS for the back side 702 is disposed on the other side of the measurement path 231. The CIS for the front side 701 is disposed facing the measurement path 231 via a reading glass (light-transmitting member) 703 as a transparent member. A backing roller 705 as a reference member is disposed on the other side of the measurement path 231 facing the reading glass (glass plate) 703. The CIS for the back side 702 is disposed facing the measurement path 231 via a reading glass (light-transmitting member) 704 as a transparent member. The backing roller 706 is disposed on one side of the measurement path 231 facing the reading glass 704.

[0025] The sheet is transported in the transport direction CD. The transport roller pairs (transport means) 211, 212, and 213 transport the sheet at a stable transport speed. The transport roller pairs 211, 212, and 213 are driven by a transport motor (driving means) 252. The reading glasses 703 and 704 function as guide members that guide the movement of the sheet to stabilize the position of the sheet in the focal depth direction (sheet thickness direction) of the front CIS 701 and the back CIS 702. The surfaces of the backing rollers 705 and 706 are black to clearly contrast with the edges of the sheet.

[0026] (Backing roller) The back CIS 702 and the backing roller 706 will be described with reference to Figs. 5 and 6. The front CIS 701 and the backing roller 705 have the same structure as the back CIS 702 and the backing roller 706, and therefore their description will be omitted. Fig. 5 is a cross-sectional view of the back CIS 702 taken along the conveying direction CD. Fig. 6 is a cross-sectional view of the backing roller 706 seen along the conveying direction CD. The reading glass 704 is disposed directly above the back CIS 702. The backing roller 706 is disposed opposite the reading glass 704 at the reading position BR, and forms a gap (space) G(n) through which the sheet conveyed by the conveying roller pair 211 passes. The sheet is conveyed to the gap G(n) between the reading glass 704 and the backing roller 706 (two-dot dashed line). The size of the gap G(n) can be changed according to the thickness of the sheet.

[0027] A conveying guide 708 is disposed upstream of the backing roller 706 in the conveying direction CD. The conveying guide 708 guides the sheet to the reading position BR without the sheet moving about. The sheet enters a clearance (gap) C between the reading glass 704 and the conveying guide 708. The conveying guide 708 guides the sheet, improving the reading accuracy of the back side CIS 702 at the reading position BR and preventing the sheet from jamming in the clearance C. The clearance C can be changed according to the thickness of the sheet, similar to the gap G(n). It is preferable that the clearance C is larger than the gap G(n) set within the focal range of the back side CIS 702. In order to change the gap G(n) and the clearance C, abutting members (cam members) 707 are disposed at both ends of the backing roller 706 in the axial direction as a change means for changing the size of the gap G(n). The abutting member 707 is brought into contact with the reading glass 704 by a biasing member such as a spring 814 (FIG. 6).

[0028] The abutting member 707 is rotatably supported on a shaft (rotation shaft) 808. The backing roller 706 is rotatably supported on the shaft 808. The outer periphery of the abutting member 707 has an eccentric shape. The eccentric shaft of the abutting member 707 is rotatably supported coaxially with the rotation shaft of the backing roller 706. The outer periphery (contact surface) 707a of the abutting member 707 rotates in a state of contacting the surface (reference surface) of the reading glass 704, thereby changing the distance between the shaft 808 and the reading glass 704. This changes the distance between the backing roller 706 and the reading glass 704 in the focal depth direction of the rear CIS 702. In this embodiment, the outer periphery 707a of the abutting member 707 contacts the surface of the reading glass 704. However, this embodiment is not limited to this. An outer peripheral surface 707a of the abutting member 707 may come into contact with another member of the front / back registration section 700, for example, the surface (reference surface) of a support member that supports the reading glass 704. A shaft (rotation shaft) 808 that rotatably supports the backing roller 706 is held by a holding member 815. The holding member 815 integrally holds the conveying guide 708, so that the position of the conveying guide 708 is also adjusted in conjunction with the adjustment of the gap G(n). This improves the reading accuracy for various sheet thicknesses and makes it possible to prevent sheet jams.

[0029] The abutting member 707 rotates and is held at each rotational position RP, so that the gap G(n) can be switched between five stages: G(1), G(2), G(3), G(4), and G(5). The rotational positions RP(1), RP(2), RP(3), RP(4), RP(5), RP(6), RP(7), and RP(8) correspond to the gaps G(1), G(2), G(3), G(4), G(5), G(4), G(3), and G(2), respectively. The gap G(n) has the following relationship: G(1) <G(2)<G(3)<G(4)<G(5)

[0030] Furthermore, the conveying guide 708 rotatably holds the shaft 808 of the backing roller 706. At the same time that the abutting member 707 rotates to switch the gap G(n), the clearance C(n) can also be switched between five levels: C(1), C(2), C(3), C(4), and C(5). The rotational positions RP(1), RP(2), RP(3), RP(4), RP(5), RP(6), RP(7), and RP(8) correspond to the clearances C(1), C(2), C(3), C(4), C(5), C(4), C(3), and C(2), respectively. The clearance C(n) has the following relationship: C(1) <C(2)<C(3)<C(4)<C(5)

[0031] The abutting member 707 rotates by receiving drive from a gap switching motor 802 as a drive source via drive connection gears 812, 807, 806, and 805. The abutting member 707 stops rotating and is held at a rotation position RP(n) of the set gap G(n). The drive of the gap switching motor 802 is transmitted to the abutting members 707 on both sides in the axial direction by a drive transmission shaft 809, so that the abutting members 707 on both sides in the axial direction are held at the same gap G(n). The rotation position RP of the abutting member 707 is detected based on the detection result of a gap switching sensor 803 that detects a sensor flag 810 arranged on the drive transmission shaft 809. The switching of the gap G(n) is controlled based on the detection result of the gap switching sensor 803. In this embodiment, the gap G(n) is switched between five stages. The control unit (second control means) 251 controls the rotation of the abutting member 707 so that the size of the gap G(n) becomes a first size when the thickness of the sheet conveyed by the conveying roller pair 211 is a first thickness. The control unit 251 controls the rotation of the abutting member 707 so that the size of the gap G(n) becomes a second size larger than the first size when the thickness of the sheet conveyed by the conveying roller pair 211 is a second thickness that is thicker than the first thickness.

[0032] Meanwhile, the backing roller 706 rotates in conjunction with the movement of the sheet. The backing roller 706 receives drive from a backing motor 801, which is a drive source different from the drive source of the abutting member 707, and rotates at the same peripheral speed as the sheet conveying speed. The drive of the backing motor 801 is transmitted to the backing roller 706 via a motor pulley, a timing belt 804, and a backing drive pulley 811. The peripheral speed of the backing roller 706 is the same as the sheet reading speed, so the image on the sheet is not rubbed by the backing roller 706, and dirt on the reading glass 704 and its surroundings is reduced.

[0033] The reading and conveying state when the thickness of the sheet P is thin will be described with reference to Figs. 7 and 8. Figs. 7 and 8 are explanatory diagrams of reading a thin sheet P(1). In the case of a thin sheet P(1), the gap G is set to G(1) and the clearance C is set to C(1). The abutting member 707 is rotated to the rotation position RP(1) of the gap G(1) based on the detection result of the gap switching sensor (backing roller position sensor) 803, stopped, and held there. The conveying roller pair 211 and 212 are rotated in the arrow directions in Figs. 7 and 8 to convey the sheet P(1) to the gap G(1). The backing roller 706 is rotated in the arrow directions in Figs. 7 and 8 at the sheet reading speed.

[0034] Here, the gap G(1) is expressed as follows using the thickness of the sheet P(1) and the allowance gap A: Gap G(1) = thickness of sheet P(1) + allowance gap A Gap G(1) guides sheet P(1) between the reading glass 704 and the backing roller 706, and a marginal gap A is provided so as to reduce the turbulence (wobble) of sheet P(1) in the focal direction of the back-side CIS 702. In addition, clearance C(1) is also set to an amount according to the thickness of sheet P(1), so that sheet P(1) can be conveyed to the back-side CIS 702 while reducing the turbulence of sheet P(1).

[0035] 9 and 10, the reading and conveying state when the thickness of the sheet P is thick will be described. FIGS. 9 and 10 are explanatory diagrams of reading a thick sheet P(n). In the case of a thick sheet P(n), the gap G is set to G(n) and the clearance C is set to C(n). The abutting member 707 is rotated to the rotation position RP of the gap G(n) based on the detection result of the gap switching sensor 803, stopped, and held. The conveying roller pair 211 and 212 are rotated in the arrow direction in FIGS. 9 and 10 to convey the sheet P(n) to the gap G(n). The backing roller 706 is rotated in the arrow direction in FIGS. 9 and 10 at the sheet reading speed.

[0036] Here, the gap G(n) is expressed as follows using the thickness of the sheet P(n) and the allowance gap A: Gap G(n) = thickness of sheet P(n) + allowance gap A The gap G(n) guides the sheet P(n) between the reading glass 704 and the backing roller 706, and a marginal gap A is provided so as to reduce the turbulence (wobbling) of the sheet P(n) in the focal direction of the back-side CIS 702. In addition, the clearance C(n) is also set to an amount according to the thickness of the sheet P(n), so that the sheet P(n) can be conveyed to the back-side CIS 702 while reducing the turbulence of the sheet P(n).

[0037] 11 is a diagram showing a gap switching table. As shown in FIG. 11, in this embodiment, the basis weight BW of the sheet P is 52 g / m 2 From 400 g / m 2 As shown in FIG. 11, the thickness of the sheet P is set to 0.15 mm to 0.50 mm. The clearance A is set to 0.20 mm to 0.40 mm. For example, when the basis weight BW is 150 g / m 2 For the following sheet P(1), the rotational position RP of the abutting member 707 is set to the gap G(1), the amount of the gap G(1) is 0.35 mm, and the clearance C is 2.15 mm. For example, when the basis weight BW is 300 g / m 2 Larger than 400g / m 2For the following sheet P(4), the rotational position RP of the abutting member 707 is set to gap G(4), the amount of gap G(4) is 0.90 mm, and the clearance C is 2.70 mm. When the sheet P is not read, the rotational position RP of the abutting member 707 is set to gap G(5), the amount of gap G(5) is 1.20 mm, and the clearance C is 3.00 mm. In this embodiment, as shown in FIG. 11, the gap G can be set to five levels. The basis weight BW and the thickness of the sheet roughly correspond to each other, and the thickness increases as the basis weight BW increases. However, there are exceptions depending on the type of sheet. The values ​​shown in FIG. 11 are merely examples, and this embodiment is not limited to these.

[0038] (Modification of the abutment member) In this embodiment, the gap G(n) is switched in five stages, but is not limited to this. The gap G(n) may be switched in four stages or less, or in six stages or more. In this embodiment, the abutting member 707 is formed in a bilaterally symmetrical shape, but is not limited to this. For example, FIG. 12 is a diagram showing a modified example of the abutting member. FIG. 12(a) is a cross-sectional view of the abutting member 1707 according to the modified example. The outer periphery of the abutting member 1707 has an eccentric shape. The eccentric shaft of the abutting member 1707 is rotatably supported coaxially with the rotation shaft of the backing roller 706.

[0039] By rotating the abutting member 1707 and holding it at each rotational position RP, the gap G(n) can be switched between eight levels: G(1), G(2), G(3), G(4), G(5), G(6), G(7), and G(8). The rotational positions RP(1), RP(2), RP(3), RP(4), RP(5), RP(6), RP(7), and RP(8) correspond to the gaps G(1), G(2), G(4), G(6), G(8), G(7), G(5), and G(3), respectively. The gap G(n) has the following relationship: G(1) <G(2)<G(3)<G(4)<G(5)<G(6)<G(7)<G(8)

[0040] As shown in FIG. 12(a), on the outer peripheral surface (contact surface) 1707a of the abutting member 1707, the maximum gap G(8) is disposed 180 degrees opposite to the minimum gap G(1). Between the maximum gap G(8) and the minimum gap G(1), gaps G(2), G(3), G(4), G(5), G(6) and G(7) are disposed alternately. This is to suppress the load on the backing motor 801 when the gap G(n) is switched. In the modified example shown in FIG. 12(a), the maximum gap G(8) (maximum value) is achieved at the rotation position (first rotation position) RP(5), and the minimum gap G(1) (minimum value) is achieved at the rotation position (second rotation position) RP(1). The contact surface of the abutting member 1707 that contacts the reading glass 704 at rotational position RP(5) where the maximum gap G(8) is achieved is positioned 180 degrees opposite to the contact surface of the abutting member 1707 that contacts the reading glass 704 at rotational position RP(1) where the minimum gap G(1) is achieved.

[0041] In this embodiment, the multiple rotation positions RP(1), RP(2), RP(3), RP(4), RP(5), RP(6), RP(7), and RP(8) are arranged at equal angular intervals. However, the multiple rotation positions RP may be arranged at any angular intervals other than equal angular intervals. In this embodiment, as shown in FIG. 12(a), the rotation positions RP(2), RP(3), and RP(4) are arranged on the first side SE1 from the rotation position (second rotation position) RP(1) to the rotation position (first rotation position) RP(5). The rotation positions RP(6), RP(7), and RP(8) are arranged on the second side SE2 from the rotation position (first rotation position) RP(5) to the rotation position (second rotation position) RP(1). The multiple rotation positions RP are arranged alternately on the first side SE1 and the second side SE2 opposite to the first side SE1 in ascending order of the multiple gaps (multiple gaps) G(n).

[0042] Fig. 12(b) is a cross-sectional view of abutting member 2707 according to another modified example. For example, when the outer peripheral surface (abutment surface) 2707a of the abutting member 2707 is configured as shown in Fig. 12(b), the maximum gap G(8) and the minimum gap G(1) are positioned adjacent to each other. Since the outer peripheral surface 2707a of the abutting member 2707 between the minimum gap G(1) and the maximum gap G(8) is a steep surface, the load on the backing motor 801 increases when the gap G(n) is switched. This requires the motor to be made larger, which leads to increased costs.

[0043] 13 is a diagram showing a gap switching table of the modified abutting member 1707. When the modified abutting member 1707 shown in FIG. 12(a) is used, the basis weight BW of the sheet P is 52 g / m 2 From 450g / m 2 As shown in FIG. 13, the thickness of the sheet P is set to a range of 0.15 mm to 0.60 mm. The clearance A is set to a range of 0.15 mm to 0.40 mm. For example, when the basis weight BW is 100 g / m 2 For the following sheet P(1), the rotational position RP of the abutting member 1707 is set to the gap G(1), and the amount of the gap G(1) is 0.3 mm. For example, when the basis weight BW is 200 g / m 2 Larger than 300g / m 2 For the following sheet P(4), the rotational position RP of the abutting member 1707 is set to gap G(4), and the gap G(4) is 0.80 mm. When reading of sheet P is not performed, the rotational position RP of the abutting member 1707 is set to gap G(8), and the amount of gap G(8) is 1.20 mm. When the abutting member 1707 according to the modified example is used, the gap G(n) is set to eight stages, as shown in FIG. 13. The above is an explanation of the abutting member 1707 according to the modified example. Below, we return to the explanation of the case where the gap G(n) is set to five stages using the abutting member 707 according to this embodiment.

[0044] As described above, the gap G is expressed as follows: Gap G = thickness of sheet P + allowance gap A When the clearance gap A is small, particularly when the clearance gap A is a negative value, the sheet P is forced into the gap G, which is smaller than the thickness of the sheet P. This causes a large shock vibration when the leading edge of the sheet P enters the gap G, and a large load during transport, resulting in greater transport unevenness, jamming, and reduced reading and transport performance. In addition, the sheet P is pressed strongly against the reading glass 704, which can scratch the reading glass 704 or cause the image to peel off, resulting in soiling. Therefore, it is necessary to set the clearance gap A to an appropriate value. The gap G is set to be equal to or larger than the thickness of the sheet P.

[0045] On the other hand, if the clearance A is large, the curled sheet is likely to wobble (wobble) in the reading section between the reading glass 704 and the backing roller 706. If the back surface of the sheet P moves away from the guaranteed reading area in the focal direction of the back surface CIS 702, the resolution decreases and flare occurs. In the back surface CIS 702 of this embodiment, if the back surface of the sheet P moves away from the front surface of the reading glass 704 in the focal direction by 0.5 mm or more, reading errors may occur. Therefore, as shown in FIG. 11, the amount of the gap G and the number of stages of the rotational position RP of the abutting member 707 are set so that the clearance A is in the range of 0.1 mm to 0.5 mm.

[0046] In this embodiment, the read gap amount 920 in which the gap G is set based on the gap switching table shown in FIG. 11 is provided in the sheet library 900. FIG. 14 is a diagram showing the sheet library 900. In the sheet library 900, the gap G is set corresponding to the type of sheet. The gap G is automatically determined by the user setting the type of sheet from the operation unit 180. FIG. 15 is a diagram showing a sheet library edit screen 1001 displayed on the operation unit 180. The user can select and set the type of sheet 910 from the sheet library edit screen 1001. When the type of sheet 910 is set, the gap G is automatically set from the read gap amount 920. In this embodiment, the user sets the information of the sheet from the operation unit 180. However, for example, information on the thickness of the sheet may be obtained by a media sensor 142 (FIG. 1) provided on the conveying path. The media sensor 142 detects the characteristics of the sheet. The detection result of the media sensor 142 is input to the printer controller 103. The printer controller 103 as an acquisition unit may acquire information regarding the thickness of the sheet based on the detection result of the media sensor 142 .

[0047] (Front and back registration feedback configuration) The measurement by the front and back registration section 700 and the feedback destination of the measurement result will be described. When the image forming apparatus 101 receives a request from the print position adjustment 1002 in the sheet library editing screen 1001 shown in Fig. 15 by the user operating the operation section 180, the image forming apparatus 101 forms a patch image 820 (Fig. 16) as an adjustment chart on the sheet P. In addition, the printer controller 103 transmits the amount of gap G corresponding to the basis weight BW of the sheet P to the control section 251 of the adjustment unit 200. The control section 251 controls the gap switching motor 802 according to the amount of gap G to rotate the abutting member 707, and switches the rotation position RP of the abutting member 707 according to the detection result of the gap switching sensor 803.

[0048] 16 is a diagram showing a patch image 820 formed on a sheet P. The front and back registration section 700 reads the front and back surfaces of the sheet P, on which the patch image 820 is formed as an adjustment chart, by the front CIS 701 and back CIS 702, respectively, while conveying the sheet P by the conveying roller pairs 211, 212, and 213. The front and back surfaces of the sheet P are successively read by the front CIS 701 and back CIS 702, and the read line images are joined together to synthesize image data, and measurement is performed from the synthesized image.

[0049] 16(a) is a diagram showing a surface measurement pattern image 822 obtained by reading the surface of a sheet P on which a patch image 820 is formed, by the surface CIS 701. The four patch images 820 are formed in the four corner areas of the surface measurement pattern image 822. The surface measurement pattern image 822 includes a leading edge 822a and a trailing edge 822b in the conveying direction CD of the sheet P, and a left edge 822c and a right edge 822d along the conveying direction CD. The conveying direction CD of the 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.

[0050] The image processing unit 260 detects the detection coordinates (X 01 ,Y 01 ), (X 11 ,Y 11 ), (X 21 ,Y 21 ) and (X 31 ,Y 31 The image processing unit 260 calculates the detection coordinates (X 41 ,Y 41 ), (X 51 ,Y 51 ), (X 61 ,Y 61 ) and (X 71 ,Y 71 The image processor 260 calculates the detection coordinates (X 01 ,Y 01 )~(X 71 ,Y 71), the amount of distortion of the image on the front side and the amount of misalignment between the sheet P and the image are measured. Based on the amount of distortion and the amount of misalignment of the image on the front side, the image processing unit 260 calculates first geometric adjustment values ​​901 (FIG. 14) that can instruct the image shape correction unit 320 to correct the shape. The first geometric adjustment values ​​901 include the lead position, side position, main scanning magnification, sub-scanning magnification, perpendicularity, and rotation amount.

[0051] 16(b) is a diagram showing a back surface measurement pattern image 823 obtained by reading the back surface of a sheet P on which a patch image 820 is formed by the back surface CIS 702. The four patch images 820 are formed in the four corner areas of the back surface measurement pattern image 823. The back surface measurement pattern image 823 includes a leading edge 823a and a trailing edge 823b in the conveying direction CD of the sheet P, and a left edge 823c and a right edge 823d along the conveying direction CD.

[0052] The image processing unit 260 detects the detection coordinates (X 02 ,Y 02 ), (X 12 ,Y 12 ), (X 22 ,Y 22 ) and (X 32 ,Y 32 The image processing unit 260 calculates the detection coordinates (X 42 ,Y 42 ), (X 52 ,Y 52 ), (X 62 ,Y 62 ) and (X 72 ,Y 72 The image processor 260 calculates the detection coordinates (X 02 ,Y 02 )~(X 72 ,Y 72), the amount of distortion of the image on the back side and the amount of misalignment between the sheet P and the image are measured. Based on the amount of distortion and the amount of misalignment of the image on the back side, the image processing unit 260 calculates second geometric adjustment values ​​902 (FIG. 14) that can instruct the image shape correction unit 320 to correct the shape. The second geometric adjustment values ​​902 include the lead position, the side position, the main scanning magnification, the sub-scanning magnification, the perpendicularity, and the amount of rotation.

[0053] The first geometric adjustment value 901 and the second geometric adjustment value 902 calculated by the image processing unit 260 are transmitted to the sheet library 900 in the image forming apparatus 101 through the communication unit 250. The first geometric adjustment value 901 and the second geometric adjustment value 902 are stored in the sheet library 900 as front and back parameters. In this manner, the setting values ​​are stored in the sheet library 900 for each sheet type 910. By reading out the setting values ​​according to the sheet type 910 on which the print job is executed and correcting the image position and image distortion, it is possible to output a print image in which the front and back printing positions are corrected with high accuracy. Here, the front surface measurement pattern image 822 and the back surface measurement pattern image 823 exemplified in this description may be measured before the execution of the print job, or may be automatically measured at a predetermined timing as calibration during the execution of the print job.

[0054] (Control Action) Hereinafter, the control operation of conveying the sheet P in the image forming apparatus 101 and the adjustment unit 200 will be described with reference to FIG. 17. FIG. 17 is a flow chart of the control operation of conveying the sheet P. The control unit 251 executes the control operation according to a program stored in an internal memory (not shown). When a job is input by a user from the operation unit 180, the control unit 251 starts the control operation. The control unit 251 judges 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 makes each member of the image forming apparatus 101 and the adjustment unit 200 wait at the home position (HP) (S1102). At this time, in order to guide the sheet P to the through path 230 in the adjustment unit 200, the control unit 251 controls the flapper switching motor 240 to make the flapper 221 wait in the downward direction (through path position) (S1102).

[0055] The image forming apparatus 101 forms an image on the sheet P (S1103). The adjustment unit 200 receives the sheet P on which the image has been formed from the image forming apparatus 101 (S1104). The control unit 251 controls the conveying motor 252 to discharge the sheet P to the post-processing apparatus 600 through the through path 230 by the first conveying roller 201, the second conveying roller 202, the third conveying roller 203, and the fourth conveying roller 204 (S1105). The control unit 251 determines whether the sheet P is the last sheet (S1106). If the sheet P is not the last sheet (NO in S1106), the control unit 251 returns the process to S1101. If the sheet P is the last sheet (YES in S1106), the control unit 251 ends the control operation.

[0056] On the other hand, when the user selects the sheet type 910 from the sheet library 900 using the operation unit 180 and selects the print position adjustment 1002, a front and back registration job is submitted. If the job is a front and back registration job (NO in S1101), the control unit 251 causes each member of the image forming apparatus 101 and the adjustment unit 200 to wait at the home position (HP) (S1107). At this time, the flapper 221 is caused to wait in the upward direction (measurement path position) in order to guide the sheet P to the measurement path 231 in the adjustment unit (S1107).

[0057] The image forming apparatus 101 forms patch images 820 as adjustment charts on both sides of the sheet P (S1108). The control unit 251 receives the basis weight and thickness value of the selected sheet type 910 from the sheet library 900 (S1109). The control unit 251 controls the gap switching motor 802 to rotate the abutting member 707 and set the gap G according to the thickness value of the sheet (S1110). The adjustment unit 200 receives the sheet P on which the patch image 820 is formed from the image forming apparatus 101 (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 and back registration unit 700 by the transport roller pairs 205, 206, 207, 208, 209, and 210.

[0058] The control unit 251 reads the patch images 820 formed on both sides of the sheet P by the front CIS 701 and the back CIS 702 and the sheet P (S1113), and obtains a front measurement pattern image 822 and a back measurement pattern image 823. The front and back registration unit 700 performs high-resolution line image synthesis, and measures the print position deviation 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 901 and a second geometric adjustment value 902 from the front measurement pattern image 822 and the back measurement pattern image 823. The image processing unit 260 stores them in the sheet library 900 of the image forming apparatus 101 through the communication unit 250 (S1114). This completes the print position adjustment for front and back registration.

[0059] The sheet P that has passed through the front and back registration section 700 is conveyed to the through path 230 by the conveyance roller pair 214 (S1115). Thereafter, the sheet P is conveyed to the discharge path 232 by the third conveyance roller 203, and is discharged to the post-processing device 600 by the fourth conveyance roller 204 (S1105). The control section 251 determines whether the sheet P is the last sheet (S1106), and if the sheet P is the last sheet (YES in S1106), the control section 251 ends the control operation.

[0060] According to this embodiment, it is possible to reduce dirt on the reading glass 703 and to stably read the image on the sheet P. In this embodiment, image processing unit 260, control unit (control means) 251, printer controller 103, and engine control unit 312 may each be configured with at least one processor and execute each function. Also, image processing unit 260 and control unit (control means) 251 may each be configured with at least one processor, and printer controller 103 and engine control unit 312 may each be configured with at least one processor. [Explanation of symbols]

[0061] 100...Image forming system 101 Image forming apparatus 211, 212, 213... Transport roller pairs 251...Control section 312 Engine control unit 700 Front and back registration section 701...CIS for surface 702...CIS for back side 703, 704: Reading glass 705, 706: Backing roller 707···Abutment member G···Gap P···Sheet

Claims

1. an image forming section for forming an image on a first sheet; a conveying means for conveying the first sheet on which an image has been formed by the image forming unit; A transparent member; a reading means having a reading sensor that reads an image on the first sheet being conveyed by the conveying means through the transparent member at a reading position in a conveying direction in which the first sheet is conveyed; an opposing member provided at the reading position in the transport direction and on an opposite side of the transparent member from the reading means, the opposing member being disposed such that the first sheet being transported by the transport means passes through a gap between the opposing member and the transparent member; An eccentric cam for changing the size of the gap; A control means; Equipped with The eccentric cam is capable of stopping at at least a first position, a second position, a third position, and a fourth position, a rotation angle between the first position and the second position is a first angle, a rotation angle between the second position and the third position is a second angle, a rotation angle between the third position and the fourth position is a third angle, and a rotation angle between the fourth position and the first position is a fourth angle, and the first angle to the fourth angle are each equal to one another; The control means a control unit for controlling a geometric characteristic of an image formed on a second sheet by the image forming unit based on the image read by the reading unit, and the image forming unit forms an image on the second sheet based on the geometric characteristic controlled by the control unit; Obtaining information regarding a thickness of the first sheet; When the thickness of the first sheet is a first thickness, the eccentric cam is controlled to stop at the first position so that the size of the gap becomes a first size, and when the thickness of the first sheet is a second thickness that is thicker than the first thickness, the eccentric cam is controlled to stop at the third position so that the size of the gap becomes a second size that is larger than the first size; the first size gap is the smallest gap and the second size gap is the largest gap; The first position and the third position of the eccentric cam are positions that are opposed to each other by 180 degrees.

1. An image forming system comprising:

2. With a reference surface, the eccentric cam has an eccentric shape having a contact surface that contacts the reference surface, 2. The image forming system according to claim 1, wherein the gap is changed by rotating the eccentric cam with the contact surface in contact with the reference surface.

3. 3. The image forming system according to claim 2, wherein the reference surface is provided on the transparent member.

4. the opposing member is a roller, 4. The image forming system according to claim 1, wherein the eccentric cam is rotatably supported coaxially with the roller.

5. the opposing member is a roller, 5. The image forming system according to claim 1, wherein the roller is driven by a drive source different from a drive source for the eccentric cam.

6. 6. The image forming system according to claim 1, wherein the opposing member is a roller having a black outer circumferential surface.

7. a conveying guide disposed upstream of the opposing member in the conveying direction, 7. The image forming system according to claim 1, wherein the eccentric cam changes a gap between the transparent member and the transport guide.

8. 8. The image forming system according to claim 1, wherein the reading sensor is a contact image sensor.

9. a sensor provided in a conveying path through which the first sheet passes and configured to detect a thickness of the first sheet; 9. The image forming system according to claim 1, wherein the control means obtains the information regarding the thickness of the first sheet from the sensor.

10. 10. The image forming system according to claim 1, wherein the first sheet is nipped by the opposing member and the transparent member in the gap between the opposing member and the transparent member, and is transported by the opposing member.

11. the eccentric cam changes a size of the gap by changing a rotational position of the eccentric cam in accordance with a thickness of the first sheet; The image forming system of any one of claims 1 to 10, characterized in that when the eccentric cam is located at the first position, the gap is the first size, when the eccentric cam is located at the third position different from the first position, the gap is the second size different from the first size, and when the eccentric cam is located at the second position different from the first position and the third position, the gap is a third size different from the first size and the second size.

12. the eccentric cam has a first cam and a second cam driven by the same driving source, 5. The image forming system according to claim 4, wherein the first cam is provided on one end side of the roller, and the second cam is provided on the other end side of the roller.

13. 13. The image forming system according to claim 1, further comprising a sensor for detecting a rotational position of the eccentric cam.

14. The eccentric cam is further capable of stopping at at least a fifth position, a sixth position, a seventh position, and an eighth position; the fifth position is between the first position and the second position, the sixth position is between the second position and the third position, the seventh position is between the third position and the fourth position, and the eighth position is between the fourth position and the first position; 14. The image forming system according to claim 1, wherein a rotation angle between the first position and the fifth position is a fifth angle, a rotation angle between the fifth position and the second position is a sixth angle, a rotation angle between the second position and the sixth position is a seventh angle, a rotation angle between the sixth position and the third position is an eighth angle, a rotation angle between the third position and the seventh position is a ninth angle, a rotation angle between the seventh position and the fourth position is a tenth angle, a rotation angle between the fourth position and the eighth position is an eleventh angle, and a rotation angle between the eighth position and the first position is a twelfth angle, and the fifth angle to the twelfth angle are each equal to one another.

15. The image forming system of claim 14, wherein when the eccentric cam is located at the first position, the gap is the first size, when the eccentric cam is located at the second position, the gap is the third size, when the eccentric cam is located at the third position, the gap is the second size, when the eccentric cam is located at the fourth position, the gap is the fourth size, when the eccentric cam is located at the fifth position, the gap is the fifth size, when the eccentric cam is located at the sixth position, the gap is the sixth size, when the eccentric cam is located at the seventh position, the gap is the seventh size, and when the eccentric cam is located at the eighth position, the gap is the eighth size, and the first size to the eighth size are each different from each other.

16. an image forming section for forming an image on a first sheet; A transparent member; a reading sensor that reads the image on the first sheet conveyed from the image forming unit through the transparent member at a reading position in a conveying direction in which the first sheet is conveyed; an opposing member that is provided at the reading position in the transport direction and is provided on an opposite side of the transparent member from the reading sensor, the opposing member being disposed such that the first sheet being transported passes through a gap between the opposing member and the transparent member; An eccentric cam for changing the size of the gap; A control means; Equipped with The eccentric cam is capable of stopping at at least a first position, a second position, a third position, and a fourth position, a rotation angle between the first position and the second position is a first angle, a rotation angle between the second position and the third position is a second angle, a rotation angle between the third position and the fourth position is a third angle, and a rotation angle between the fourth position and the first position is a fourth angle, and the first angle to the fourth angle are each equal to one another; The control means Obtaining information regarding a thickness of the first sheet; When the thickness of the first sheet is a first thickness, the eccentric cam is controlled to stop at the first position so that the size of the gap becomes a first size, and when the thickness of the first sheet is a second thickness that is thicker than the first thickness, the eccentric cam is controlled to stop at the third position so that the size of the gap becomes a second size that is larger than the first size; the first size gap is the smallest gap and the second size gap is the largest gap; The first position and the third position of the eccentric cam are positions that are opposed to each other by 180 degrees, setting image forming conditions for forming an image on a second sheet based on the image data acquired by the reading sensor; 1. An image forming system comprising:

17. 1. An image reading apparatus for reading an image on a sheet conveyed from an image forming apparatus that forms an image on the sheet, comprising: A transparent member; a reading sensor that reads the image on the sheet conveyed from the image forming apparatus through the transparent member at a reading position in a conveying direction in which the sheet is conveyed; an opposing member that is provided at the reading position in the conveying direction and is provided on an opposite side of the transparent member from the reading sensor, the opposing member being disposed such that the conveyed sheet passes through a gap between the opposing member and the transparent member; An eccentric cam for changing the size of the gap; A control means; Equipped with The eccentric cam is capable of stopping at at least a first position, a second position, a third position, and a fourth position, a rotation angle between the first position and the second position is a first angle, a rotation angle between the second position and the third position is a second angle, a rotation angle between the third position and the fourth position is a third angle, and a rotation angle between the fourth position and the first position is a fourth angle, and the first angle to the fourth angle are each equal to one another; The control means Obtaining information regarding a thickness of the sheet; When the thickness of the sheet is a first thickness, the eccentric cam is controlled to stop at the first position so that the size of the gap becomes a first size, and when the thickness of the sheet is a second thickness that is thicker than the first thickness, the eccentric cam is controlled to stop at the third position so that the size of the gap becomes a second size that is larger than the first size, the first size gap is the smallest gap and the second size gap is the largest gap; The first position and the third position of the eccentric cam are positions that are opposed to each other by 180 degrees.

1. An image reading apparatus comprising:

18. a conveying unit that conveys the sheet on which the image is formed by the image forming device, 18. The image reading apparatus according to claim 17, wherein the reading position is located downstream of the conveying means in the conveying direction.

19. With a reference surface, the eccentric cam has an eccentric shape having a contact surface that contacts the reference surface, 19. The image reading device according to claim 17, wherein the gap is changed by rotating the eccentric cam with the contact surface in contact with the reference surface.

20. 20. The image reading device according to claim 19, wherein the reference surface is provided on the transparent member.

21. the opposing member is a roller, 21. The image reading device according to claim 17, wherein the eccentric cam is rotatably supported coaxially with the roller.

22. the opposing member is a roller, 22. The image reading apparatus according to claim 17, wherein the roller is driven by a drive source different from a drive source for the eccentric cam.

23. 23. The image reading device according to claim 17, wherein the opposing member is a roller having a black outer circumferential surface.

24. 24. The image reading apparatus according to claim 17, further comprising a transport guide disposed upstream of the opposing member in the transport direction, the transport guide supporting the opposing member.

25. 25. The image reading device according to claim 17, wherein the reading sensor is a contact image sensor.

26. a sensor provided in a conveying path through which the sheet passes and configured to detect a thickness of the sheet; 26. The image reading apparatus according to claim 17, wherein the control means obtains the information relating to the thickness of the sheet from the sensor.

27. an operation unit that receives input of the information on the thickness of the sheet by a user when using the image reading device; 27. The image reading apparatus according to claim 17, wherein the control unit acquires the information on the thickness of the sheet from the operation unit.

Images