JP2005263376A - Sheet transport device and image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet transport device surely separating and feeding sheets without complicating the structure, and an image forming apparatus equipped with the same. <P>SOLUTION: In the sheet transport device for separating the stacked sheets one by one and feeding the same in a separating and feeding means, the separating and feeding means includes: a separating and transport roller 8 for applying the feeding force to the sheet; a separation pad 6 for pressing the sheet to the separating and transport roller 8 and applying resisting force to the second and following sheets to separate the first sheet; and a post-separation pad 72 for pressing the sheet separated by the separation pad 6 to the separating and transport roller 8 to apply the feeding force of the separating and transport roller 8 to the sheet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet conveying apparatus applicable to an image processing apparatus such as a scanner, a copying machine, and a laser beam printer, and an image processing apparatus including the sheet conveying apparatus. More specifically, the present invention separates a plurality of sheets one by one. The present invention relates to a sheet conveying apparatus provided with a separating and feeding means for feeding out, placing on a predetermined position, and conveying, and an image processing apparatus provided with the sheet conveying apparatus.

  2. Description of the Related Art Conventionally, a sheet conveying apparatus is applied to an automatic document feeder that automatically feeds a document (sheet) to an image reading unit of an image forming apparatus such as a copying machine and automatically feeds it. The originals are separated one by one by the separating unit and fed to a predetermined position.

  Japanese Patent Application Laid-Open No. 9-58885 describes a document conveying apparatus (sheet conveying apparatus) equipped with a retard type separating device to which an example of this type of separating unit and feeding unit is applied. That is, a plurality of sheets (originals) stacked on a document tray are fed out by rotation of a feeding roller, fed to a separation unit including a separation roller and a separation belt, and a separation roller rotating in a feeding direction and a sheet are returned. The separation belt that rotates in the direction is surely separated and fed one by one.

  In Japanese Patent Laid-Open No. 8-324817, separation pads are arranged, and separation and feeding are performed one by one in the same manner as described above.

  In the above example, a plurality of set sheets are sequentially fed out from the lowermost sheet, but the apparatus for feeding out from the uppermost sheet is also provided with the same separating and feeding means. Further, a Duplo pad type separation feeding means comprising a separation roller and a separation friction pad is a well-known technique.

JP-A-9-58885 JP-A-8-324817

  However, in the above conventional example, a plurality of separation rollers and separation belts must be alternately arranged and driven, so that the structure is complicated, the number of parts is large, and the cost is high.

  In the Duplo pad separation method, the cost is advantageous because the structure is simple and the number of parts is small. However, since the separation feeding is performed only by the frictional force between the separation roller and the separation pad with respect to the sheet, there is a place where the performance is inferior to the retard system in which the separation belt is driven. Depending on the surface friction, surface shape, thickness, or rigidity of the sheet, there are problems such as double feed that is not separated and fed by two or more sheets, or jammed sheets that cannot be fed and are not fed.

  And the automatic document feeder ensures various sheets with different states, such as stiff and thick paper originals, thin thin paper originals, color image originals with silicon oil, glossy coated paper originals, etc. Must be separated and fed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a sheet conveying apparatus that can reliably separate and supply sheets without complicating the structure, and an image forming apparatus including the sheet conveying apparatus. .

  A typical means in the present invention for solving the above problems is a sheet conveying apparatus that separates and conveys a plurality of stacked sheets one by one in the separating and feeding means, wherein the separating and feeding means is a sheet. A feeding rotating body for applying a feeding force, and a sheet for pressing the sheet against the feeding rotating body, for applying resistance to the second and subsequent sheets, and separating the first sheet A first pressing member; and a second pressing member for pressing the sheet separated by the first pressing member against the feeding rotating body and applying a feeding force by the feeding rotating body to the sheet. It is characterized by having.

  In the present invention, by arranging the first pressing member and the second pressing member that press the sheet against the feeding rotating body, the number of parts is small, and a problem such as double feeding or non-feeding occurs with a simple configuration. High separation performance and feeding performance can be achieved.

  A copying machine (reader unit and printer unit) provided with an automatic document feeder that is a sheet conveying apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  In FIGS. 1 and 2, 150 is a reader unit, 2 is an automatic document feeder, and 300 is a printer unit.

[Explanation of leader section]
As shown in FIG. 1, the reader 150 guides, to a lens 157 and a CCD 158, a lamp 152 that irradiates light on the document surface, and reflected light from the document P corresponding to the light irradiated by the lamp 152. It has mirrors 153, 155, and 156. The lamp 152 and the mirror 153 are attached to the first optical bench 159, and the mirrors 155 and 156 are attached to the second optical bench 151 (not shown).

  The optical benches 159 and 151 are coupled to a motor 314 (see FIG. 3) by wires (not shown), and are controlled to move in parallel with the document table glass 3 by the rotation of the motor 314.

  The home position of the first optical bench 159 is detected by a position sensor (not shown), and the optical bench 159 and 151 are moved by rotating the motor 314 forward and backward with reference to the position of the position sensor, and the original platen glass 3 The upper document is optically scanned.

  The motor 314 is configured by a stepping motor. The motor 314 is connected to an encoder 302 (see FIG. 3), and the output of the encoder 302 can recognize how many pulses the optical benches 159 and 151 have moved. That is, the positions of the optical benches 159 and 151 can be grasped by the encoder pulse from the position sensor and the encoder 302.

  The reflected light from the document is guided to the lens 157 via the mirrors 153, 155, and 156, and is condensed on the CCD 158 by the lens 157. The CCD 158 photoelectrically converts the reflected light reflecting the document information and outputs it as an electronic image signal.

  Under such a configuration, in a state where the first optical table 159 is stopped at the document reading position, a flow reading mode for reading document information while the document is conveyed by the automatic document feeder 2 and the document on the document table glass 3. The document information can be read in two modes, ie, the document table glass reading mode, while reading the document information while moving the optical tables 159 and 151 in the sub-scanning direction.

  FIG. 3 is a block diagram showing a schematic configuration of a reader control system. A lamp 152 for irradiating light on the document surface, a motor 314 for scanning the document by moving the optical benches 159 and 151 to the sub-scanning method, a CCD 158 for photoelectrically converting reflected light from the document surface, and an output signal of the CCD 158 for A / D conversion A / D conversion circuit 301, encoder 302 connected to motor 314, lamp 152 for irradiating light on the document, position sensor 315 for positioning optical bench 159 at the home position, and regular in ADF document reading mode A backup RAM 303 for setting a document reading position and a scanner controller 304 are provided.

[Description of printer section]
The printer unit 300 is an image forming unit using known electrostatic latent image image formation. Here, the printer unit, which is an image output unit 300, will be described with reference to FIG.

  Reference numeral 100 denotes an upper cassette. The sheets in the cassette are separated and fed one by one by the action of the separation claw and the feeding roller 101 and guided to the registration roller 106. Reference numeral 102 denotes a lower cassette. The sheets in the cassette are separated and fed one by one by the action of the separation claw and the feeding roller 103 and guided to the registration roller 106. A manual feed guide 104 guides the sheets one by one to the registration roller 106 via the roller 105. A sheet stacking device (deck type) 108 includes a middle plate 108a that is moved up and down by a motor or the like. The sheets on the middle plate are separated and fed one by one by the action of the feeding roller 109 and the separation claw, and the conveying roller 110 is fed. Led to.

  112 is a photosensitive drum, 114 is a developing unit, 115 is a transfer charging unit, and 116 is a separation charging unit, which constitute an image forming unit.

  Reference numeral 117 denotes a conveyance belt that conveys the image-formed sheet, 118 denotes a fixing device, 119 denotes a conveyance roller, and 120 denotes a diverter. The image-formed sheet is guided to the discharge roller 121 by the diverter 120 and conveyed into the sorter 122. The sorter 122 includes a non-sort tray 122a, a sort bin tray 122b, a non-sort tray discharge roller 122c, and a sort bin tray discharge roller 122d. . Note that a discharge tray may be mounted instead of the sorter.

  In the case of double-sided copying or multiple copying, the sheet after fixing is branched by the diverter 120 and conveyed by the conveying roller 201. In the case of double-sided copying, the belt 202, 204, the pass 206, and the discharge roller 205 are passed to the intermediate tray 200. Discharged. In the case of multiple copying, the sheet is discharged to the intermediate tray 200 by the diverter 203. 209 and 210 are half-moon rollers for feeding the sheet, 211 is a pair of separation rollers, and 213, 214 and 215 are transport rollers for transporting the sheet to the registration roller 106.

[Description of automatic document feeder]
The automatic document feeder 2 is provided above the reader unit 150 so as to be openable and closable with respect to the platen glass 161 and the document table glass 3 via hinge mechanisms 95 and 96. Details of the automatic document feeder 2 will be described below with reference to the drawings.

[Description of Document Tray]
In FIG. 1, a document tray 4 is for stacking sheet-shaped documents P. A pair of width direction restricting plates are arranged on the document tray 4 so as to be slidable in the document width direction. By regulating the width direction of the documents P stacked on the document tray 4 by the width direction regulating plate, it is possible to ensure the conveyance stability during feeding.

[Description of separation unit]
Next, a description will be given of the configuration of a separation unit serving as a separation feeding unit that separates and conveys sheets one by one. A feeding roller 5 is provided above the document tray 4. The feeding roller 5 rotates as the separation conveyance roller 8 rotates and feeds a sheet document. The feeding roller 5 normally takes a position retracted above the home position (solid line position in the figure) so as not to disturb the document setting operation. When the feeding operation is started, it descends and comes into contact with the upper surface of the original P. Since the feeding roller 5 is pivotally supported by the arm 5a, the feeding roller 5 can be moved up and down by swinging the arm.

  The separation pad 6 is disposed on the side opposite to the separation conveying roller 8 as a feeding rotating body for applying a feeding force to the sheet, and applies pressure to the separation conveying roller 8 side. The separation pad 6 is formed of a rubber material or the like whose frictional force is slightly smaller than that of the separation / conveying roller 8. The sheet bundle fed by the feeding roller 5 is separated one by one from the top sheet in order and conveyed by the separation / conveying roller 8. To do. The separation / conveying roller 8 is made of a rubber material such as urethane, silicon, or EPDM, and has a friction coefficient of about 2.0.

  The separation transport roller 8 and the separation pad 6 are configured as a separation unit. Specifically, as shown in FIG. 4, the separation pad 6, the pre-separation pad 67 that holds the post-separation pad 72, the separation pad spring 77, the post-separation pad spring 76, and the separation spring base that face the separation transport roller 8. 78 is assembled as a unit, and can be replaced as a separation unit. The separation spring base 78 is provided with a separation pad spring 77 as a first urging member constituted by a compression coil spring that urges the separation pad 6 in the direction of the separation conveyance roller 8 and a post-separation pad 72 in the direction of the separation conveyance roller 8. Different springs of the post-separation pad spring 76 as a second urging member composed of a compression coil spring that is energized are fitted into ribs that are receiving portions having an outer shape slightly larger than the inner diameter of the spring. Facilitates sex.

  5 shows a state in which the separation spring base 78 is removed, where (a) is a plan view, (b) is a front view, and (c) is a bottom view. A predetermined spring pressure is applied to the separation pad 6 by the separation pad spring 77 and the post-separation pad 72 by the post-separation spring 76, respectively.

(Pre-separation pad)
6A and 6B are diagrams showing details of the pre-separation pad 67, where FIG. 6A is a perspective view, FIG. 6B is a plan view, and FIG. 6C is a front view. The pre-separation pad 67 is made of a resin or the like, and is fastened with screws (not shown) to the main body (shaded surface). A pre-separation friction pad 70 made of a rubber material is bonded and fixed along the sheet passing surface on the sheet passing surface side, and a resin sheet pre-separating sheet 71 is bonded and fixed to the upper surface. The pre-separation sheet 71 has low friction, can be guided without resistance against the sheet, the pre-separation friction pad 70 exposed only at the top part gives resistance to the sheet, and the leading edge of the entering sheet bundle can be broken into a wedge shape. it can. By breaking into a wedge shape, the number of sheets entering the separation pad 6 is suppressed, and the separation performance is assisted.

  Furthermore, holes 68 for supporting the separation pad 6 are formed in the arm portions 69 on both sides of the pre-separation pad 67. A fulcrum shaft 61 (see FIG. 4) of the separation pad is fitted in the hole 68 so that it can freely move in the rotational direction and the vertical direction. Normally, the fulcrum shaft 61 is positioned upward by the urging force of the separation pad spring 77 and the post-separation pad spring 76, and when the sheet enters the separation pad 6, the fulcrum shaft 61 rotates or depends on the thickness of the sheet. It can be easily moved downward.

(Separation pad)
FIG. 7 shows details of the separation pad 6 as a first pressing member for pressing the sheet against the separation conveying roller 8 and applying resistance to the second and subsequent sheets to separate the first sheet. FIG. Here, (a) is a perspective view, (b) is a plan view, and (c) is a front view. The separation pad 6 is made of a resin or the like and has a fulcrum shaft 61. On the sheet passing surface side, a rubber friction pad 63 is arranged in a U shape in order to block a plurality of sheets entering the separation pad 6. The friction pad 63 is made of a rubber material such as urethane, silicon, or EPDM, and has a sheet shape with a thickness of about 0.5 mm. The friction coefficient with paper is about 1.2 to 1.5, which is higher than the friction coefficient of the conventional Duplo friction pad. Therefore, resistance is also high.

  Since the foam rubber sponge 62 that can be easily deformed is disposed on the lower surface of the friction pad 63, the friction pad 63 uniformly contacts along the surface of the separation conveying roller 8 and applies pressure over a wide range. Further, the foam rubber sponge 62 is disposed only on the upstream side (hereinafter simply referred to as “upstream side”) of the separation pad 6 in the sheet conveying direction, and the friction pad 63 is foamed as shown in FIGS. The upstream side of the boundary 64 with the rubber sponge 62 is bonded to the rubber sponge 62, and the downstream side in the sheet conveying direction (hereinafter simply referred to as “downstream side”) is bonded and fixed to the resin surface of the separation pad 6. For this reason, the pressure applied to the sheet from the upstream to the downstream rapidly changes to a high pressure when passing through the boundary 64 from a wide range of light pressure by the rubber sponge 62. A rib 66 for disposing the separation pad spring 77 is disposed on the immediate lower surface, and is fitted by a rib having an outer shape slightly larger than the inner diameter of the separation pad spring 77.

(Pad after separation)
FIG. 8 shows details of the post-separation pad 72 as a second pressing member for pressing the sheet separated by the separation pad 6 against the separation conveyance roller 8 and applying a feeding force to the sheet by the separation conveyance roller 8. FIG. Here, (a) is a perspective view, (b) is a plan view, and (c) is a front view. The base material of the post-separation pad 72 is formed of resin or the like, and the post-separation pad sheet 73 is bonded and fixed to the sheet passing surface. Further, when the fulcrum hole 75 extending from the arm 74 is fitted into the fulcrum shaft 61 of the separation pad 6, it is rotated at the same position as the fulcrum where the separation pad 6 moves. A protrusion rib having the same function as the rib 66 of the separation pad 6 is formed immediately below the post-separation pad sheet 73, and a post-separation pad spring 76 is similarly disposed on the protrusion rib.

  After separation, the pad sheet 73 is formed of an ultra-low friction sheet. For example, a high-density polyethylene sheet or the like has a coefficient of friction with paper of 0.1 or less. The post-separation pad sheet 73 comes into contact with the separation conveying roller 8 to apply pressure and has low friction, so that a conveying force can be applied to the sheet. Furthermore, since the post-separation pad sheet 73 is arranged at the center of the U-shaped friction pad 63, it is possible to continuously apply pressure to the sheet moving from upstream to downstream.

(Combination of separation pad and pad after separation)
As described above, the separation pad 6 and the separated pad 72 can swing independently about the fulcrum shaft 61. The separation pad 6 has a separation pad spring 77, and the separated pad 72 has a separated spring 76. A predetermined spring pressure is applied to the separation conveyance roller 8 side. Since the separation pad 6 and the post-separation pad 72 have the same fulcrum, the structure is simple and the unit can be easily exchanged. Further, since it can rotate independently, even if the separation pad 6 is displaced, it does not affect the post-separation pad 72. Therefore, there is an effect that a stable pressure is always maintained and the separation performance is not deteriorated.

  In addition, the friction coefficient between the friction pad 63 and the sheet is μp1, the separation coefficient between the pad sheet 73 and the sheet is μp2, the maximum friction coefficient between the sheet and the sheet is μs, and the friction coefficient between the sheet and the separation conveying roller 8 is μk. , Μp2 <μs <μp1 <μk.

  μp1 is necessary friction to prevent double feed. Since μp2 is extremely low friction and smaller than the sheet friction, the feeding force is generated by driving the separation conveying roller 8. For example, color print originals have high adhesion, and therefore μs is high. In order to prevent double feeding even in such a sheet, μp1 is set higher than before. Therefore, there is no problem that the sheet is sent along. Since μp1 and μk are set close to each other, there is a concern that the feeding force of the sheet decreases and there is a concern about feeding failure. However, the feeding force is reliably given by the post-separation pad 72 in the vicinity of the separation pad 6 downstream. Sent downstream.

  FIG. 9 shows a state where sheets are being fed. A separation conveyance roller 8 driven in the direction of the arrow contacts and conveys the upper surface of the uppermost sheet P1. The leading edge of the second sheet P2 is blocked by the exposed top of the pre-separation friction pad 70 and the lower surface of the uppermost sheet P1. Double feeding by the subsequent feeding of the second and subsequent sheets may be blocked by either the pre-separation friction pad 70 or the separation pad 6.

  FIG. 10 shows a state in which the tip of the second sheet P2 is blocked by the friction pad 63. In the present embodiment, the pressing force with the sheet of the friction pad 63 is increased, and the second sheet is reliably prevented from being fed by the wall of the boundary 64 with the downstream side where the friction coefficient becomes higher. . Further, there is a concern that the conveyance force of the separation conveyance roller 8 is lowered by increasing the friction coefficient to prevent double feeding, but the total balance is improved by supplementing the conveyance force by the action of the pad 73 after separation. I'm taking it. In addition, since the friction pad 63 has a U-shape and the post-separation pad 73 is continuously disposed, only a short nip width region in contact with the separation conveying roller 8 is used to prevent the double feeding. The feeding and conveying force for non-feeding is compatible at a high level. Therefore, the separation and feeding performance equivalent to the conventional retard is maintained with a compact and simple configuration.

  FIG. 11 shows a state where the second sheet P2 and the third sheet P3 are blocked by the friction pad 63. FIG. When a plurality of sheets enter the separation pad 6, the fulcrum shaft 61 naturally moves in a direction (downward) away from the separation conveyance roller 8, so that the pressure acts on the sheet in the entire area without being biased. This is particularly effective for sheet bundles that are thick and have high rigidity, and eliminate the problems of double feeding and non-feeding in all types of paper.

[Description of transport unit]
Next, a conveyance configuration of the sheet separated by the separation unit having the above configuration will be described with reference to FIG. The registration roller 12 and the registration driven roller 11 are registration means for aligning the leading ends of the documents fed by the separation unit, and abutting the leading end of the document separated toward the nip portion of the stationary registration roller pairs 11 and 12, A loop is generated to correct skew and align the tips.

  The second registration roller 28 and the second registration driven roller 27 correct the skew of the document switched back by the discharge reversal unit and align the leading ends in order to read the back side images on both sides.

  Next, the sheet is conveyed toward the platen glass 161 by the lead roller 22 and the lead driven roller 14. The document conveyed to the platen glass 161 is picked up by the jump table 162 and conveyed by the lead discharge roller 23 and the lead discharge driven roller 16.

  A platen roller 24 is arranged with a 0.3 mm gap with respect to the platen glass 161. Along with the sheet pressing rollers 24a and 24b provided on the platen roller side, the document is pressed so as not to float from the platen glass.

  A swingable flapper 31 is urged clockwise and normally takes a position as shown in FIG. 32 is a discharge reversing roller, and 18 is a discharge reversing roller. The discharge reversing roller 32 can be rotated forward and backward, and has a function of discharging the document to the discharge tray 10 and a function of switching back the document. The discharge reversing roller can be contacted and separated by a separation solenoid 57 (see FIG. 12).

  Reference numeral 34 denotes an intermediate roller, and reference numeral 33 denotes an intermediate roller. These have a function of conveying the switched-back original to the second registration roller pair 27, 28.

[Description of drive system]
Next, a drive system for driving the rollers and the like will be described with reference to FIG.

  The separation motor 50 is a stepping motor, and separates and conveys a document by forward and reverse rotation. When the separation motor 50 is rotated in the feeding direction and the clutch 53 is turned on (connected state), the feeding roller 5 is lowered from above, which is the home position, and pressed against the uppermost sheet of the sheet document on the document tray 4. At the same time, the feeding roller 5 and the separation conveying roller 8 are driven. At this time, since the drive is transmitted to the registration roller 12 via the one-way clutch, the registration roller 12 is stopped.

  When the separation motor 50 is rotated in the conveying direction which is the reverse direction to the feeding direction and the clutch 53 is turned off (disconnected state), the registration roller 12 is rotated.

  The read motor 51 is a stepping motor that drives the second registration roller 28, the lead roller 22, the platen roller 24, and the lead discharge roller 23, and drives each roller at a reading speed for an image of a conveyed document. Further, the separation solenoid 57 presses and separates the discharge reversing roller 18 and the discharge reversing roller 32 at the time of double-sided document switchback.

  The discharge motor 52 is a stepping motor that drives the discharge reverse roller 32 and the intermediate roller 34. The discharge motor 52 can rotate in the forward and reverse directions. During normal rotation, the document is discharged, and the document is switched back by normal rotation, stop, and reverse rotation, and the document is conveyed to the second registration roller 28.

[Explanation of sensor]
Next, each sensor will be described with reference to FIGS. The document tray 4 is provided with a document set detection sensor 40 that is a transmission type optical sensor that detects that a sheet document P is set.

  In addition, a sheet width detection sensor that detects the length in the width direction of the document bundle P set on the document tray 4 by detecting the position of the side guide is provided at the lower portion of the document tray 4.

  The post-separation sensor 26 includes a light emitting element, a light receiving element, and a reflecting plate, and detects double feeding and feeding failure. A registration sensor 7, which is a transmission type optical sensor that detects a document, is provided between the separation conveyance roller 8 and the registration roller 12, detects the leading edge of the separated and fed document, and the amount of contact with the registration roller 12 The timing for controlling the (loop amount) is detected.

  The read sensor 13 includes a light emitting element, a light receiving element, and a reflecting plate. The read sensor 13 is provided immediately before the read roller 22 and serves as a reference signal for image reading start timing in the reading unit 160. The discharge sensor 17 includes a light emitting element, a light receiving element, and a reflection plate. The discharge sensor 17 is provided immediately before the discharge reversing roller 32, and detects the document discharge timing, switchback timing, and the like.

[Description of sheet feeding operation]
Next, an operation for feeding a document will be described. First, the case of the single-sided mode will be described. When the copy condition is input at the operation unit of the copying machine and the start key is pressed, the feeding roller 5 is lowered to feed the document. The document is reliably separated and conveyed by the separation conveyance roller 8 and the separation pad 6 as described above.

  Next, the document hits the nip portion of the resist roller 12 and the resist driven roller 11 that are stopped, and forms a loop to stop. Next, the registration roller 12 rotates, is conveyed to the second registration roller 28, passes through the lead roller 22, and is supplied to the reading unit.

  In the reading unit, the platen roller 24 and the sheet pressing rollers 24a and 24b prevent the original from floating from the platen glass 161, thereby improving the image quality.

  Next, it passes through the lead discharge roller, the flapper 31, and the discharge reverse roller 32, and is discharged face-down to the discharge tray. Further, productivity is improved by starting feeding of the next sheet when the trailing edge of the front sheet passes through the sensor after separation.

  In the double-sided mode, after reading the surface image, it is switched back by the discharge reversing roller 32, passes through the upper surface of the flapper 31, and hits the second registration rollers 28, 27 stopped by the intermediate roller 33. Form a contact loop and correct skew. Next, the second registration roller rotates and is supplied to the reading unit by the read roller 22.

  After the back side image is read, in order to adjust the document orientation, it is switched back again by the discharge reversing roller and supplied again to the reading unit. At this time, loop formation and image reading are not performed. And it is discharged face down to the discharge tray.

  As described above, in the automatic document feeder 2 of the present embodiment, when the sheet is separated and fed by the separation conveyance roller 8 and the separation pad 6, the sheet is pressed against the separation conveyance roller 8 by the post-separation pad 72. By applying the feeding force to the sheet, it is possible to achieve both high separation performance and feeding performance with a simple configuration and no problems such as double feeding and non-feeding with a small number of parts. .

  In the above-described embodiment, the separation and feeding of the sheet has been described by exemplifying an image reading apparatus (image processing apparatus) that automatically feeds a document using the automatic document feeder 2 and reads the document information. The present invention can be suitably used if it is an apparatus that separates and feeds a plurality of sheets one by one. In addition, for example, a recording sheet is fed one by one to an image forming unit, and an image is formed on the sheet. It is also effective when used for an image forming apparatus (image processing apparatus).

FIG. 3 is a diagram illustrating the configuration of an image reading apparatus and an automatic document feeder. 1 is a diagram illustrating a configuration of an image forming apparatus. It is a control block diagram of a reading apparatus. It is a diagram illustrating a separation unit of the automatic document feeder. It is a diagram illustrating a separation unit of the automatic document feeder. It is a figure explaining the pre-separation pad of the separation part of an automatic document feeder. It is a diagram illustrating a separation pad of a separation unit of the automatic document feeder. FIG. 6 is a diagram illustrating a post-separation pad of a separation unit of the automatic document feeder. FIG. 6 is a diagram illustrating separation and conveyance of an automatic document feeder. FIG. 6 is a diagram illustrating separation and conveyance of an automatic document feeder. FIG. 6 is a diagram illustrating separation and conveyance of an automatic document feeder. It is a diagram illustrating a drive system of an automatic document feeder.

Explanation of symbols

2 ... Automatic document feeder 3 ... Original plate glass 4 ... Original tray 5 ... Feed roller 6 ... Separation pad 8 ... Separation conveyance roller
10… discharge tray
12… Registration roller
22… Lead roller
23… Lead discharge roller
24… Platen roller
24a, 24b ... Sheet presser roller
28… Second registration roller
32… Discharge reversing roller
34… Intermediate roller
50… separation motor
52… discharge motor
61… fulcrum shaft
62… Foam rubber sponge
63… friction pad
64… Boundary
66… ribs
67… Pre-separation pad
68… hole
70… Pre-separation friction pad
71… Pre-separation sheet
72… Pad after separation
73… Pad sheet after separation
74 Arm
75… fulcrum hole
76… Pad spring after separation
77… Separation pad spring
78… separation spring base

Claims (7)

In a sheet conveying apparatus that separates and conveys a plurality of stacked sheets one by one in a separation feeding unit,
The separation feeding means includes
A feeding rotating body for applying a feeding force to the sheet;
A first pressing member for pressing the sheet against the feeding rotating body and applying a resistance to the second and subsequent sheets to separate the first sheet;
A second pressing member for pressing the sheet separated by the first pressing member against the feeding rotating body, and applying a feeding force by the feeding rotating body to the sheet;
A sheet conveying apparatus comprising: The friction coefficient between the first pressing member and the sheet is μp1,
The friction coefficient between the second pressing member and the sheet is μp2,
Μs, the maximum friction coefficient between sheets
The friction coefficient between the sheet and the feeding rotating body is μk,
If
μp2 <μs <μp1 <μk
The sheet conveying apparatus according to claim 1, wherein: A first urging member that urges the first pressing member toward the feeding rotating body;
A second urging member for urging the second pressing member toward the feeding rotating body;
Have
The sheet conveying apparatus according to claim 1, wherein the first pressing member and the second pressing member are independently swingable about the same fulcrum shaft. The sheet conveying apparatus according to claim 3, wherein the fulcrum shaft is movable in a direction away from the feeding rotating body. The sheet conveying apparatus according to claim 3, further comprising a receiving portion that receives the first urging member and the second urging member. The first pressing member that presses the sheet against the feeding rotating body has a larger pressing force on the sheet on the downstream side in the sheet conveying direction than on the upstream side. Sheet conveying device. In an image processing apparatus that conveys a sheet and processes an image,
An image processing apparatus comprising the sheet conveying apparatus according to claim 1.

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