Sheet feeding device and imaging device

Abstract

The present disclosure relates to a sheet feeding apparatus and an image forming apparatus. A sheet feeding apparatus includes a sheet support portion, a feeding portion, a conveying portion configured to convey a sheet fed by the feeding portion, a separation member, a return portion that pushes back the sheet toward the sheet support portion by moving from a retracted position to a projected position, and a pressing portion including a contact portion configured to contact the sheet. The pressing portion is configured to press the sheet from above by the contact portion so that the sheet is pushed toward the return portion in a state where the return portion is at the projected position and is located below the sheet.

Description

Technical Field

[0001] The present invention relates to a sheet feeding device for feeding sheet material and an imaging device equipped with the sheet feeding device. Background Technology

[0002] To date, a sheet feeding device has been proposed, which includes an automatic sheet feeder base (hereinafter referred to as an ASF base) on which a sheet is supported, a feed roller for feeding the sheet supported on the ASF base, a torque limiter that abuts against the feed roller and separates the sheets one by one, and a return rod (for example, see Japanese Patent Application Publication No. 2002-332130). A pressure plate for pressing the sheet against the feed roller is attached to the ASF base. The torque limiter is arranged in a manner that allows it to abut against and separate from the feed roller, and the return rod is configured to push the sheet back toward the ASF base.

[0003] However, the downward tilt of the ASF base, as taught in Japanese Patent Application Publication No. 2002-332130, could result in multi-page feeding of the sheet if the sheet on the ASF base moves unintentionally beyond the return rod. Summary of the Invention

[0004] According to one aspect of the present invention, a sheet feeding device includes: a sheet support portion configured to support a sheet; a feeding portion configured to move up and down between a feeding position and an upper position, wherein in the feeding position the feeding portion abuts against the sheet supported on the sheet support portion, and in the upper position the feeding portion separates upward from the sheet supported on the sheet support portion, the feeding portion being configured to feed the sheet by rotating in the feeding position; a conveying portion configured to convey the sheet fed by the feeding portion; and a separating member configured to move between abutting position and a separating position, wherein in the abutting position the separating member abuts against the conveying portion and forms a separation. The sheet includes a separation clamping portion configured to separate the sheets fed by the feed portion one by one, wherein the separation member is separated from the conveying portion at the separation position; a return portion configured to move between a protruding position and a retracted position, wherein at the protruding position the return portion protrudes into the conveying path through which the sheet passes, and at the retracted position the return portion retracts from the conveying path; the return portion protruding into the conveying path at the protruding position located between the feed portion and the separation clamping portion along the sheet conveying direction, and the return portion pushing the sheet back toward the sheet support portion by moving from the retracted position to the protruding position; and a pressing portion including a contact portion configured to contact the sheet. The pressing portion is configured to press the sheet from above through the contact portion such that the sheet is pushed toward the return portion when the return portion is located at the protruding position and below the sheet.

[0005] Other features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the printer according to this embodiment.

[0007] Figure 2 This is a perspective view showing a manual sheet feeding device.

[0008] Figure 3A This is a perspective view showing the sheet feeding unit.

[0009] Figure 3B This is a perspective view showing the pressing unit.

[0010] Figure 3C This is another perspective view showing the pressing unit.

[0011] Figure 4AThis is a perspective view showing the drive mechanism.

[0012] Figure 4B It shows a plan view of the drive mechanism.

[0013] Figure 5A This is a side view showing the manual sheet feeding device before the sheet feeding begins.

[0014] Figure 5B This is a side view showing a manual sheet feed device during sheet feeding.

[0015] Figure 5C This is a side view of the manual sheet feeder after part of the toothless gear has rotated one revolution. Detailed Implementation

[0016] Overall structure

[0017] The printer 1 used as an imaging device is a laser beam printer employing an electrophotographic system, and as... Figure 1 As shown, printer 1 includes an imaging unit 20 for forming images on sheet S, a cartridge sheet feed device 50, a manual sheet feed device 70, and a fixing unit 30. The imaging unit 20 is equipped with four processing cartridges PY, PM, PC, and PK for forming color toner images of yellow (Y), magenta (M), cyan (C), and black (K) respectively, a scanner unit 2, and an intermediate transfer belt 21.

[0018] Aside from the different colors of the resulting images, the four processing boxes PY, PM, PC, and PK have the same construction. Therefore, only the construction and imaging processing of processing box PY will be described, while the descriptions of the other processing boxes PM, PC, and PK will be omitted.

[0019] The processing cartridge PY includes a photosensitive drum 11a, a charging roller (not shown), and a developing roller 12a. The photosensitive drum 11a is constructed by applying an organic photoconductive layer to the outer periphery of an aluminum cylinder and is rotated by a drive motor (not shown). An intermediate transfer belt 21 extends over a drive roller 22, a driven roller 24, and a tension roller 23 and is rotated by the drive roller 22. Primary transfer rollers 25a, 25b, 25c, and 25d are disposed inside the intermediate transfer belt 21. The fixing unit 30 includes a fixing film 31 heated by a heater and a pressure roller 32 in pressure contact with the fixing film 31.

[0020] A cassette sheet feeder 50 is disposed below the printer 1 and stores the sheet S. The manual sheet feeder 70, which serves as the sheet feeder, includes a door 82 supported by the main body 1A of the printer 1 in an openable and closable manner, a support tray 81 supported on the door 82, a sheet feeder unit 100 for feeding the sheet S supported on the support tray 81, and a separation roller 73.

[0021] Next, the imaging operation of the printer 1 constructed as described above will be described. When an image signal is input to the scanner unit 2 from a personal computer (not shown), a laser corresponding to the image signal is emitted from the scanner unit 2 and irradiates the photosensitive drum 11a of the processing cartridge PY.

[0022] In this state, the surface of the photosensitive drum 11a is pre-charged to a predetermined polarity and potential by the charging roller, and an electrostatic latent image is formed on the surface of the photosensitive drum when laser light is irradiated from the scanner unit 2. The electrostatic latent image formed on the photosensitive drum 11a is developed by the developing roller 12a, forming a yellow (Y) toner image on the photosensitive drum 11a.

[0023] Similarly, laser light from scanner unit 2 illuminates each photosensitive drum of processing cartridges PM, PC, and PK, forming toner images of magenta (M), cyan (C), and black (K) on each photosensitive drum. The corresponding color toner images formed on the photosensitive drums are transferred to intermediate transfer belt 21 by primary transfer rollers 25a, 25b, 25c, and 25d, and then conveyed to secondary transfer roller 26 by the intermediate transfer belt 21, which is rotated by drive roller 22. Imaging processing of the various toner colors is performed at corresponding timings when the images are superimposed onto the toner images already initially transferred to intermediate transfer belt 21 upstream.

[0024] In parallel with imaging processing, sheet S is fed from either cassette sheet feeder 50 or manual sheet feeder 70. For example, when sheet S is fed from cassette sheet feeder 50, sheet S stored in cassette 51 is fed out by pick-up roller 52 and then separated one by one by transfer roller 53 and separation roller 54. When sheet S is fed from manual sheet feeder 70, sheet S supported on support tray 81, which serves as a sheet support portion, is fed by pick-up roller 71 and separated one by one by transfer roller 72 and separation roller 73. Then, sheet S is conveyed toward alignment roller pair 61 by transfer roller pair 62, 63, and 64.

[0025] The skewness of sheet S is corrected by alignment roller pair 61, and then sheet S is conveyed according to the transfer timing. Then, the full-color toner image on intermediate transfer belt 21 is transferred to sheet S by a secondary transfer bias applied to secondary transfer roller 26.

[0026] The sheet S, which has already been transferred with the toner image, is subjected to predetermined heat and pressure by the fixing film 31 and pressure roller 32 of the fixing unit 30. The toner is melted and hardened, i.e., fixing. The sheet S that has passed through the fixing unit 30 is discharged onto the sheet discharge tray 43 by the sheet discharge roller pair 41 of the sheet discharge unit 40. Figure 1 The dashed arrow shown is an example of the conveying path through which sheet S is conveyed from the cassette sheet feeder 50 to the sheet discharge roller pair 41.

[0027] Manual sheet feeding device

[0028] Next, we will refer to Figures 2 to 3C Describe the manual sheet feed device 70. For example... Figures 2 to 3C As shown, the manual sheet feeding device 70 includes attachmentable and detachable supports on the device body 1A (reference). Figure 1 The sheet feeding unit 100 and the separating roller 73 are on the sheet.

[0029] like Figure 2 As shown, the transfer guide frame 98 is fixed to the device body 1A (reference). Figure 1 The conveying guide 99 is fixed to the conveying guide frame 98. The conveying guide 99 forms part of the conveying path CP through which the sheet S supplied by the pick-up roller 71 passes.

[0030] Separation bracket 87 surrounds separation shaft 87a (reference) Figure 4A The separation roller 73 is pivotally supported on the conveying guide 99 and rotatably supported on the separation support 87. The separation roller 73, which serves as a separation member, is configured to swing (i.e., move) between an abutting position and a separating position. In the abutting position, the separation roller 73 abuts against the conveying roller 72, which serves as a conveying part. In the separating position, the separation roller 73 is separated from the conveying roller 72 by pivoting about the separation axis 87a via the separation support 87.

[0031] The separating roller 73 abuts against the conveyor roller 72 at the abutment position, forming a separating clamping section N. At this separating clamping section, the sheets S fed by the pick-up roller 71, which serves as the feed section, are separated one by one. The separating roller 73 includes a torque limiter (not shown), and when multiple sheets S are present at the separating clamping section N, the separating roller 73 serves to separate the sheets to be conveyed by the conveyor roller 72 from the other sheets. Conversely, if only one sheet S is present at the separating clamping section N, the torque limiter idles, and the separating roller 73 is driven to rotate along with the conveyor roller 72.

[0032] Furthermore, return claws 91L and 91R, serving as the return portion, are provided on the conveying guide 99, and are arranged on one side and the other side of the separating roller 73 in a width direction W orthogonal to the sheet conveying direction. The return claws 91L and 91R are configured to be able to protrude from the sheet (see [reference]). Figure 5AThe return claws 91L and 91R move between the protruding and retracted positions. In the protruding position, the return claws 91L and 91R protrude into the conveying path CP in the area between the pick-up roller 71 and the separating clamping part N along the sheet conveying direction. In the retracted position, the return claws 91L and 91R retract from the conveying path CP. Furthermore, the return claws 91L and 91R push the sheet S near the separating clamping part N back towards the support tray 81 by moving from the retracted position to the protruding position. The distance between the return claws 91L and 91R in the width direction W is set to be less than the width of the smallest sheet size that can be fed by the manual sheet feed device 70.

[0033] like Figure 3A As shown, the sheet feeding unit 100 includes a feed shaft 90, a transfer roller 72 rotatably supported at a first end of the feed shaft 90, a feed gear 92 integral with the transfer roller 72, and a lifting arm shaft 97 having a cylindrical shape and in which the feed shaft 90 is disposed. Furthermore, the sheet feeding unit 100 includes a lifting arm 74 pivotally supported on the feed shaft 90 and connected to the lifting arm shaft 97, and a roller cover 105 disposed to cover the lifting arm 74. Additionally, the sheet feeding unit 100 includes a pickup roller 71 and a pickup gear 101 rotatably supported by the lifting arm 74 and the roller cover 105, and a pressing unit 120.

[0034] The feed shaft 90 includes a connecting portion 95 located at the end opposite to the conveyor roller 72, and when connected to the device body 1A, it can input a driving force. With the feed shaft 90 rotating, the conveyor roller 72 and the feed gear 92 rotate. The rotation of the feed gear 92 is transmitted to the pickup gear 101 via a drive system (not shown) supported on the lifting arm 74, thereby causing the pickup roller 91 to rotate.

[0035] The lifting arm shaft 97 is rotatable relative to the feed shaft 90 and includes a connection to the device body 1A (reference). Figure 1 The lifting mechanism is connected to the connecting portion 96. The lifting arm shaft 97 is rotated via the connecting portion 96, thereby lowering the lifting arm 74 and roller cover 105 connected to the lifting arm shaft 97. Thus, the pickup roller 71 can be positioned in the feed position (see...). Figure 5B ) and upper position (see Figure 5A The pickup roller 71 moves up and down between the feed position and the upper position. In the feed position, the pickup roller 71 rests against the sheet supported on the support tray 81. In the upper position, the pickup roller 71 separates upward from the sheet supported on the support tray 81. In other words, the lifting arm 74 and the roller cover 105 constitute a lifting bracket 130 that supports the pickup roller 71 in a lifting manner between the feed position and the upper position.

[0036] Furthermore, the lifting arm 74 and the roller cover 105 can be configured to be pushed upward by a pressing member (not shown) or to be raised or lowered by a driven lifting arm shaft 97.

[0037] like Figure 3B and Figure 3C As shown, the pressing unit 120 includes a pressing rod 107 serving as a pivot portion, a pressing roller 108, and a torsion coil spring 109 serving as a pushing portion. The pressing rod 107 is generally L-shaped and includes a pivot 107a pivotally supported on a roller cover 105 and a rod portion 107b extending in a direction orthogonal to the pivot 107a. In other words, the rod portion 107b pivots about the pivot 107a relative to a lifting bracket 130 including the roller cover 105. The pressing roller 108, serving as a contact portion and a roller, is rotatably supported on the end of the rod portion 107b opposite to the pivot 107a. The pressing roller 108 is located between the conveyor roller 72 and the pickup roller 71 in the sheet conveying direction CD described below. As described below, the pressing roller 108 is configured to press the sheet S toward the return claws 91L and 91R. The pressing roller 108 is positioned in the sheet conveying direction CD closer to the conveying roller 72 and the return claws 91L and 91R than the pick-up roller 71. Therefore, the pressing roller 108 can press the sheet S near the return claws 91L and 91R. Furthermore, the pivot 107a is located upstream of the pick-up roller 71 in the sheet conveying direction CD. This allows the lever portion 107b to have a longer length and prevents excessive pressure from the pressing roller 108 on the sheet S.

[0038] Furthermore, the helical portion 109a of the torsion coil spring 109 is attached to the pivot 107a, wherein the first end 109b of the torsion coil spring 109 engages with the roller cover 105, and the second end 109c of the torsion coil spring 109 engages with the rod portion 107b. Thus, the pressing rod 107 is pushed toward the pressing roller 108 in a direction away from the roller cover 105, i.e., pushed downwards.

[0039] Drive mechanism

[0040] Next, we will refer to Figure 4A and Figure 4B Describes the drive mechanism 200 used to drive the manual sheet feed device 70. For example... Figure 4A and Figure 4B As shown, the drive mechanism 200 includes a motor M serving as a drive source, a first transmission gear G1, a second transmission gear G2, a solenoid unit 79, a partial toothless gear 78 serving as a control gear, and a linkage part 80.

[0041] According to this embodiment, motor M can transmit driving force to both the cassette sheet feeding device 50 and the manual sheet feeding device 70. Motor M meshes with a first transmission gear G1 and a second transmission gear G2. The first transmission gear G1 transmits driving force to the cassette sheet feeding device 50. The second transmission gear G2 transmits driving force to the manual sheet feeding device 70. The second transmission gear G2 transmits drive force to the connecting portion 95 (see reference) of the feed shaft 90 via a drive system (not shown). Figure 3A The clutch can be located between the motor M and the first transmission gear G1 or between the motor M and the second transmission gear G2. Furthermore, the motor M, the first transmission gear G1, and the second transmission gear G2 are examples of drive transmission configurations, and this technology is not limited thereto.

[0042] The solenoid unit 79 includes a solenoid 79a and an engagement claw 79b driven by the solenoid 79a. When the solenoid 79a is not energized, the engagement claw 79b engages with the partially toothless gear 78. In this state, the toothless portion 78a of the partially toothless gear 78 is opposite the second transmission gear G2. In other words, when the solenoid 79a is not energized, rotation of the second transmission gear G2 is not transmitted to the partially toothless gear 78.

[0043] With solenoid 79a energized, the engagement claw 79b disengages from the partial gear 78, causing the partial gear 78 to rotate slightly by a spring mounted on it, thereby engaging the gear portion 78b of the partial gear 78 with the second transmission gear G2. After the engagement claw 79b disengages from the partial gear 78, solenoid 79a immediately de-energizes, so that the partial gear 78 is locked back into place by the engagement claw 79b after one revolution. As described, the partial gear 78 is driven by the driving force from motor M, controlled to rotate one revolution and stop after each revolution.

[0044] The linkage 80 includes a control cam 84 connected to a partial toothless gear 78, a reciprocating gear 77, an idler gear 85, a left return pawl drive member 75a, a separation bracket drive mechanism 75b, a connecting member 76, and a right return pawl drive member 86. The reciprocating gear 77 is configured to reciprocate like a pendulum around a swing center 77a in conjunction with the control cam 84. The reciprocating gear 77 meshes with the idler gear 85, which in turn meshes with the left return pawl drive member 75a. This causes the left return pawl drive member 75a to reciprocate along the width direction W.

[0045] The left return pawl drive member 75a is connected to the right return pawl drive member 86 via a connecting member 76, and the right return pawl drive member 86 and the left return pawl drive member 75a reciprocate integrally in the width direction W. Both the left return pawl drive member 75a and the right return pawl drive member 86 include cam portions (not shown), which engage with return pawls 91L and 91R respectively to move return pawls 91L and 91R to the protruding position and the retracted position.

[0046] Furthermore, the left return claw drive member 75a is also connected to the separation bracket drive mechanism 75b, and the separation bracket drive mechanism 75b and the left return claw drive member 75a reciprocate integrally in the width direction W. The separation bracket drive mechanism 75b is provided with a cam portion 75c, which engages with the separation bracket 87 and causes the separation bracket 87 to pivot about the separation axis 87a. In other words, by the reciprocating movement of the separation bracket drive mechanism 75b in the width direction W, the separation roller 73 held on the separation bracket 87 swings to the abutment position and the separation position.

[0047] More specifically, the left return claw drive member 75a is pushed in the width direction W by a pushing member (not shown). In this embodiment, the left return claw drive member 75a is directed toward the direction approaching the separating roller 73. Figure 4B (Pushing to the right in the middle). Furthermore, the separating bracket 87 is pushed towards the separating roller 73 and closer to the conveyor roller 72 by a pushing member (not shown). The reciprocating gear 77 is moved along the direction shown by the control cam 84 pressing the reciprocating gear 77. Figure 4B The left return claw drive member 75a rotates counterclockwise, overcoming the pushing force of the left return claw drive member 75a and moving towards... Figure 4B The cam portion 75c moves to the left. In this state, the cam portion 75c and the separating bracket 87 abut against each other, thereby positioning the separating roller 73 in the separating position against the pushing force of the separating bracket 87. In this state, the return claws 91L and 91R are in the protruding position.

[0048] Simultaneously, with the solenoid 79a energized, part of the toothless gear 78 rotates, causing the control cam 84 to move away from the reciprocating gear 77. Therefore, the left return pawl drive member 75a moves towards the separating roller 73 by the pushing force of the left return pawl drive member 75a (i.e., Figure 4B The cam portion 75c moves to the right. Then, the cam portion 75c separates from the separating bracket 87, and the separating roller 73 is positioned in the abutment position by the pushing force of the separating bracket 87. At this time, the return claws 91L and 91R are in the retracted position.

[0049] As described, with the drive motor M driven, driving force is input to the feed shaft 90 via the second transmission gear G2, the partial toothless gear 78, and an idler gear (not shown), causing the transfer roller 72 and the pickup roller 71 to rotate. Then, with the solenoid 79a energized, the partial toothless gear 78 rotates one revolution, and the lifting arm shaft 97 and the lifting arm 74 rotate via the connecting part 96 through the movement of a lifting mechanism (not shown) that moves in association with the rotation of the partial toothless gear 78. Therefore, each time the partial toothless gear 78 rotates one revolution, the pickup roller 71 rises and falls to the upper position, the feed position, and the upper position in a specified sequence. Each time the partial toothless gear 78 rotates one revolution, the separating roller 73 moves to the separating position, the abutting position, and the separating position in a specified sequence, and the return claws 91L and 91R move to the protruding position, the retracted position, and the protruding position in a specified sequence.

[0050] In other words, the linkage part 80 includes the lifting mechanism and lifting arm shaft 97 (not shown above), and performs the lifting of the pickup roller 71, the movement of the separation roller 73, and the movement of the return claws 91L and 91R by linkage with a portion of the toothless gear 78.

[0051] Feeding sequence and operation of the pressure roller

[0052] Next, we will refer to Figures 5A to 5C Describe the feeding sequence of the manual sheet feeding device 70 and the operation of the pressing roller 108. Figure 5A This is a side view showing the manual sheet feed device 70 before the sheet feeding begins. Figure 5B This is a side view showing the manual sheet feed device 70 during sheet feeding. Figure 5C This is a side view of the manual sheet feeder 70 after the partial toothless gear 78 has rotated one revolution.

[0053] like Figure 5A As shown, with the door 82 open from the device body 1A, the pickup roller 71 is in the upper position, the separation roller 73 is in the separation position, and the return claws 91L and 91R are in the protruding position. In this state, when viewed along the rotation axis direction of the pickup roller 71 (i.e., the width direction W), the pickup roller 71 protrudes to the outside of the device body 1A (see reference). Figure 1 Then, by closing the door 82 relative to the device body 1A, the sheet feed unit 100 is stored in the device body 1A.

[0054] Before inputting a sheet feed command to the manual sheet feed device 70, the pick-up roller 71 is in the upper position and separated from the support surface 81a of the support tray 81. Therefore, the user can easily place the sheet S on the support surface 81a.

[0055] Before the sheet S is supported on the support surface 81a, the pressing roller 108 is also separated from the support surface 81a. That is, when the sheet S is not supported on the support surface 81a, a gap is formed between the pressing roller 108 and the support surface 81a. Therefore, even if the user slides a small amount of sheet on the support surface 81a from the user side, sheet positioning failures (the sheet stops before reaching the set position due to resistance received from the pressing roller 108) can be reduced. In addition, noise that may be generated due to the pressing roller 108 colliding with the support surface 81a after the last sheet on the support surface 81a has been fed can be prevented. According to this embodiment, the movement of the pressing rod 107 beyond the predetermined position can be controlled by the roller cover 105 of the lifting bracket 130, so that the pressing roller 108 does not abut against the support surface 81a.

[0056] With the support tray 81 in the open position, opened from the main body 1A, the support surface 81a slopes downward toward the downstream side in the sheet transport direction CD. In other words, the support surface 81a is sloped so that its downstream portion in the sheet transport direction CD is lower. Therefore, the sheet S on the support surface 81a is designed to slide downward toward the return claws 91L and 91R located in the protruding position by gravity. Afterward, the sheet S remains in a state where the leading edge of the sheet S is near the return claws 91L and 91R.

[0057] Depending on the number of sheets S placed by the user on the support surface 81a, the sheets S abut against the pressing roller 108. However, the pressing roller 108 is driven to rotate relative to the sheets S placed on the support surface 81a. That is, the pressing roller 108 is driven to rotate by the frictional force received from the sheets S. Furthermore, since the pivot 107a of the pressing rod 107 is arranged upstream of the pressing roller 108 in the sheet conveying direction CD, the pressing rod 107 and the pressing roller 108 can retract in the upward direction even if the pressing roller 108 contacts the sheets S. Therefore, the user can easily place the sheets S on the support surface 81a without damaging the sheets S.

[0058] With a feed command input to the manual sheet feed device 70, a sheet presence sensor (not shown) determines whether sheet S is present on the support tray 81. When sheet S is detected on the support tray 81, the motor M is driven, the solenoid 79a is energized, and part of the toothless gear 78 begins to rotate. Thus, as... Figure 5B As shown, the lifting arm 74 and the linkage part 80 are driven, and the pick-up roller 71 descends to the feed position against the sheet S. In addition, the separating roller 73 moves to the contact position, and the return claws 91L and 91R move to the retracted position from the conveyor path CP.

[0059] There are cases where the return claws 91L and 91R move away from each other by the cam portions of the left return claw drive member 75a and the right return claw drive member 86, and move to the retracted position by their own weight; and there are also cases where the return claws 91L and 91R move to the retracted position by being pressed by the sheet S. Since the movement of the return claws 91L and 91R in the retraction direction is uncontrolled, even if the sheet S is pressed against before retraction, the return claws 91L and 91R can retract from the conveying path CP without damaging the leading edge of the sheet S.

[0060] Since the pick-up roller 71 and the conveyor roller 72 rotate due to the rotation of the feed shaft 90, the sheet S is fed by the pick-up roller 71 located at the feed position. Since the pick-up roller 71 only needs to convey the leading edge of the sheet S to the separation clamping part N, the pick-up roller 71 is configured to rise toward the upper position via the lifting arm 74 after a predetermined amount of sheet S has been conveyed.

[0061] After the front end of the sheet S has been conveyed to the clamping part of the alignment roller pair 61, the separating roller 73 moves from the abutting position to the separating position. Furthermore, after the separating clamping part N has been released, the returning claws 91L and 91R move from the retracted position to the protruding position, pushing the sheet remaining near the separating clamping part N back toward the support tray 81.

[0062] Now, as Figure 5C As shown, the alignment roller pair 61 (reference) is used as the downstream conveying section. Figure 1 The sheet being conveyed is referred to as the preceding sheet S1, while the sheet pushed back by the return claws 91L and 91R is referred to as the following sheet S2. Due to the frictional force received from the preceding sheet S1 or the weight of the sheet itself, the following sheet S2 tends to move downstream along the sheet conveying direction CD. In particular, in a configuration where the support surface 81a is inclined downward toward the downstream side of the sheet conveying direction CD, the following sheet S2 tends to move toward the downstream side of the sheet conveying direction CD. If the following sheet S2 moves downstream along the sheet conveying direction CD beyond the return claws 91L and 91R, multi-page feed occurs because the separation clamping part N is released.

[0063] To reduce the occurrence of multi-sheet feeding, the pressing roller 108, supported on the pressing rod 107, presses the previous sheet S1 from above, such that the previous sheet S1 is pushed towards the return claws 91L and 91R when the return claws 91L and 91R are below the previous sheet S1. In other words, the pressing unit 120 (see reference) which includes the pressing rod 107 and the pressing roller 108 as the pressing part... Figure 3BThe pressing roller 108 presses down on the previous sheet S1 from above, pushing it towards the return claws 91L and 91R. In this state, the pressing roller 108 is positioned closer to the support surface 81a than the ends of the return claws 91L and 91R that are in contact with the sheet. In other words, the pressing roller 108 is positioned closer to the base of the return claws 91L and 91R than the ends of the return claws 91L and 91R. The pressing rod 107 supporting the pressing roller 108 is supported by its own weight and the torsion coil spring 109 (see reference). Figure 3B The material is pushed downwards around pivot 107a. As long as the previous sheet S1 is pushed toward the return claws 91L and 91R, the direction in which the pressing roller 108 presses the previous sheet S1 can deviate from the return claws 91L and 91R. In this embodiment, the direction of movement of the pressing roller 108 via the rod 107b can deviate from the direction toward the return claws 91L and 91R.

[0064] By pressing the previous sheet S1 from above using the pressing roller 108, the gap D1 formed between the previous sheet S1 and the return claws 91L and 91R can be reduced, and the movement of the subsequent sheet S2 beyond the return claws 91L and 91R can be prevented. In other words, since multi-page feeding would occur if the subsequent sheet S2 were conveyed along the sheet conveying direction through the gap D1 formed between the previous sheet S1 and the return claws 91L and 91R, the pressing roller 108 narrows the gap D1 to control the conveying of the subsequent sheet S2. Furthermore, as... Figure 2 As shown in Figure 3, conveying ribs 74a and 97a are arranged on both sides of the return claw 91L in the width direction W. Conveying rib 74a is arranged on the lifting arm 74, and conveying rib 97a is arranged on the lifting arm shaft 97. Conveying ribs 74a and 97a also have the function of reducing the gap D1 by pressing the previous sheet S1 from above towards the return claws 91L and 91R, similar to the pressing roller 108. The return is achieved when the trailing edge of the previous sheet S1 has passed the pressing roller 108. Figure 5A The state shown.

[0065] According to this embodiment, the manual sheet feeding device 70 repeats the above operation for each sheet to transfer the sheet on the support tray 81. Furthermore, the support tray 81 is integrally provided with the door 82, and the support tray 81 moves between an open position and a closed position by opening and closing the door 82 relative to the device body 1A. The sheet feeding unit 100, including the pressing unit 120, moves in association with the opening and closing of the door 82, and the sheet feeding unit 100 is stored in the device body 1A when not in use by closing the door 82. Therefore, the size of the printer 1 will not increase due to the use of the pressing unit 120.

[0066] As described above, according to this embodiment, by pressing the sheet S from above using the pressing roller 108 of the pressing unit 120, the gap D1 between the sheet being conveyed and the return claws 91L and 91R can be reduced. Thus, by preventing the subsequent sheet S from passing through the gap D1 and moving beyond the return claws 91L and 91R, multi-page feeding of the sheet can be avoided.

[0067] Furthermore, by constructing the pickup roller 71 in a height-adjustable manner, the pickup roller 71 can protrude outward from the main body 1A of the device only during use, along with the support tray 81, and the diameter of the pickup roller 71 can be reduced. Therefore, the overall size of the device can be reduced. Typically, if a configuration is used where the support tray, rather than the pickup roller, is raised and lowered, the motor used to raise and lower the support tray generates significant operating noise because the support tray supports a heavier sheet. This embodiment employs a configuration where the pickup roller 71 is raised and lowered instead of the support tray 81, thereby reducing the operating noise generated during sheet transport.

[0068] Furthermore, since both the pickup roller 71 and the separating roller 73 move toward and away from the conveyor roller 72 each time a sheet is conveyed, wear on the pickup roller 71, conveyor roller 72, and separating roller 73 can be reduced, resulting in a longer service life. Also, since the pickup roller 71 is in the upper position and the separating clamping part N is released when conveying the sheet via the alignment roller pair 61, conveying resistance can be reduced, and the size of the drive motor can be reduced. Moreover, since the lifting and lowering of the pickup roller 71 and the movement of the separating roller 73 and the return claws 91L and 91R are controlled by the solenoid 79a, costs can be reduced.

[0069] Other embodiments

[0070] In this embodiment, the separating roller 73 employs a torque limiter system, but the technology is not limited thereto. For example, the separating roller 73 may employ a delay roller system, wherein a driving force is input to rotate the roller in the opposite direction to the sheet conveying direction, or a separating pad may be used instead of the roller.

[0071] Furthermore, this embodiment employs return claws 91L and 91R located on the right and left sides, respectively, but the technology is not limited to this. The number of return claws can be one, or even three or more.

[0072] Furthermore, according to this embodiment, considering the conveying of sheets with easily damaged surfaces (e.g., glossy paper), the pressing roller 108 is provided at the end of the pressing rod 107, but the technology is not limited to this. For example, depending on the type of sheet being conveyed, a configuration in which the pressing rod 107 slides directly on the sheet can be adopted. In other words, a contact portion capable of contacting the sheet can be provided on a portion of the pressing rod 107.

[0073] According to this embodiment, the pressing rod 107 is pushed downward by the torsion coil spring 109, but the technology is not limited thereto. For example, a construction can be adopted in which an elastic member such as a compression spring is provided to apply the pushing force instead of the torsion coil spring 109, or in which the torsion coil spring 109 is omitted and the pressing rod 107 is designed to pivot downward by its own weight.

[0074] Furthermore, according to this embodiment, the pivot 107a of the pressing rod 107 is arranged upstream of the pressing roller 108 in the sheet conveying direction CD, but the technology is not limited to this. For example, the pivot 107a can be arranged downstream of the pressing roller 108. In addition, the pressing unit 120 including the pressing rod 107 can be supported on the device body 1A instead of on the lifting bracket 130.

[0075] This embodiment employs a solenoid unit 79 that causes part of the toothless gear 78 to stop after one revolution, but the technology is not limited to this. For example, a clutch such as an electromagnetic clutch can be used to achieve the transmission of driving force from the motor M and prevent its transmission to the manual sheet feed device 70.

[0076] Furthermore, according to this embodiment, a printer 1 employing an electrophotographic system is described as an example, but the technology is not limited thereto. For example, the technology can be applied to an imaging device employing an inkjet system, in which an image is formed on a sheet by discharging liquid ink through nozzles.

[0077] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims should be interpreted in the broadest sense to cover all variations and equivalent structures and functions.

Claims

1. A sheet feeding device, comprising: A sheet support portion, wherein the sheet support portion is configured to support the sheet; The feeding portion is configured to move up and down between a feeding position and an upper position. In the feeding position, the feeding portion abuts against the sheet supported on the sheet support portion. In the upper position, the feeding portion separates upward from the sheet supported on the sheet support portion. The feeding portion is configured to feed the sheet by rotating in the feeding position. A conveying section, the conveying section being configured to convey a sheet fed by the feeding section; A separating member is configured to move between a contact position and a separating position, wherein in the contact position the separating member abuts against the conveying portion and forms a separating clamping portion configured to separate the sheets fed by the feeding portion one by one, and in the separating position the separating member is separated from the conveying portion; The return portion is configured to move between a protruding position and a retracted position, wherein in the protruding position the return portion protrudes into the conveying path through which the sheet passes, and in the retracted position the return portion retracts from the conveying path. The return portion protrudes into the conveying path at the protruding position located between the feed portion and the separation clamping portion along the sheet conveying direction, and the return portion pushes the sheet back toward the sheet support portion by moving from the retracted position to the protruding position. as well as The pressing portion includes a contact portion configured to contact the sheet material, the pressing portion being configured to press the sheet material from above via the contact portion, such that the sheet material is pushed towards the return portion while the return portion is located at the protruding position and below the sheet material. The contact portion is arranged in the sheet conveying direction at a position closer to the conveying portion than the feeding portion.

2. The sheet feeding device according to claim 1, wherein, With the return portion in the protruding position, the feed portion is in the upper position, and the separation member is in the separation position.

3. The sheet feeding device according to claim 1 further includes a lifting bracket configured to support the feeding portion. in, The pressing portion includes a pivoting portion configured to pivotally support the lifting bracket about a pivot axis, and the contact portion is disposed on the pivoting portion.

4. The sheet feeding device according to claim 3, wherein, The pivot is positioned upstream of the contact portion in the sheet conveying direction.

5. The sheet feeding device according to claim 3, wherein, The contact portion is a roller that is rotatably supported on the pivot portion.

6. The sheet feeding device according to claim 3, wherein, The pressing portion includes a pushing portion configured to push the pivoting portion to pivot it downward about the pivot axis.

7. The sheet feeding device according to claim 1, wherein, The contact portion is arranged between the feed portion and the conveying portion in the sheet conveying direction.

8. The sheet feeding device according to claim 1, wherein, When the sheet is not supported on the sheet support portion, a gap is formed between the contact portion and the sheet support portion.

9. The sheet feeding device according to any one of claims 1 to 8, wherein, The sheet support portion includes a support surface on which the sheet is supported, and the sheet support portion is configured to open and close relative to the device body between a closed position and an open position. When the sheet support portion is in the open position, the support surface is inclined downward toward the downstream side of the sheet conveying direction.

10. The sheet feeding device according to claim 9, wherein, When viewed along the axis of rotation of the feed portion, at the feed position, the feed portion protrudes beyond the outer side of the device body.

11. The sheet feeding device according to claim 9, wherein, The support surface is configured to remain stationary when the sheet support portion is in the open position.

12. The sheet feeding device according to any one of claims 1 to 8, further comprising: A control gear, the control gear being configured to be driven by a driving force from a drive source and stopping after each rotation; as well as The linkage component is configured to cause the feed component to move up and down between the feed position and the upper position, the separation member to move between the abutment position and the separation position, and the return component to move between the retracted position and the protruding position by means of linkage with the control gear.

13. The sheet feeding apparatus according to any one of claims 1 to 8, further comprising a downstream conveying section, said downstream conveying section being arranged downstream of the separating clamping portion in the sheet conveying direction and configured to convey the sheet. in, When the return portion is located in the protruding position and below the sheet being conveyed by the downstream conveying portion, the pressing portion presses the sheet from above via the contact portion.

14. An imaging device, comprising: The sheet feeding device according to any one of claims 1 to 8; as well as An imaging unit configured to form an image on a sheet fed by the sheet feeding device.

Images