JP6602091B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus that feeds stacked sheets and an image forming apparatus including the sheet feeding apparatus.

  2. Description of the Related Art Conventionally, image forming apparatuses such as printers, facsimiles, and copiers are widely used in which an image forming unit forms an image on a sheet fed from a sheet feeding apparatus. In this sheet feeding apparatus, a sheet storage for storing sheets is provided in the apparatus main body so as to be able to be mounted and pulled out. In this sheet feeding apparatus, after the sheet storage in which the sheet is set is stored in the apparatus main body, the pickup roller disposed in the feeding holder which can be moved up and down descends from the retracted position and comes into contact with the uppermost sheet. Generally, the configuration is extended from the beginning.

  In order to feed the sheet in the sheet storage case, it is necessary that the lowered pickup roller rotates while pressing the sheet. For this reason, many sheet feeding apparatuses include an elevating device that lifts the sheets stacked in the sheet storage case to a pressing position by a pickup roller. As such an elevating device, a device including a feeding tray for stacking sheets, a drive transmission mechanism for raising and lowering the feeding tray, and a detecting means for detecting the raising and lowering position of the feeding tray has been proposed (patent) Reference 1).

JP 2003-118865 A

  As described above, when the pickup roller is supported by the feeding holder and moved up and down using the rotation shaft of the feed roller as a fulcrum, the following configuration is generally used. That is, it is configured to be supported on the shaft of the rotating shaft via the first bearing portion and the second bearing portion, and the axial thrust restricting portion of the rotation shaft of the feeding holder is provided on the feed roller shaft. Yes.

  The thrust restriction of the feed roller shaft with respect to the feed frame on the apparatus body side is performed via the first and second bearing portions that support the feed roller shaft, the drive transmission gear that rotates the feed roller shaft, the retaining ring, and the like. Done. In such a configuration, in order for the feeding holder to smoothly move up and down, the feeding holder is not clogged in the thrust direction and the sliding resistance is not increased even if the dimensions of parts related to thrust regulation vary. It is necessary to ensure sufficient clearance. Therefore, the play in the thrust direction with respect to the feeding frame of the feeding holder inevitably increases. Therefore, when a sensor flag for detecting the raising / lowering position of the feeding holder is attached to the feeding holder, the sensor flag comes into contact with the detection sensor on the feeding frame side when the backlash in the thrust direction with respect to the feeding frame increases. Inconvenience such as detection failure may occur.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet feeding apparatus and an image forming apparatus that reduce backlash in a thrust direction of a feeding holder so as not to cause inconvenience such as detection failure.

The present invention provides a sheet feeding apparatus, a stacking means sheet is stacked, a feeding roller for feeding the sheet on the stacking means, disposed downstream of the feed sheet feeding direction of the roller, the sheet a conveying roller for conveying and a conveying rotating shaft for supporting the conveyance roller, and feed frame for rotatably supporting the front Ki搬 feed rotation axis, holding the feed roller, as a fulcrum the transport rotation shaft and the feeding holder pivotable, provided on the feed holder, and the sensor flag for detecting the position of the feed holder, provided on the feed frame, a sensor for detecting the sensor flag, the It includes a feeding holder and restricting protrusion provided on either one of the feed frame, and a regulating recess provided in the other of the feed holder and the feeding frame, the limiting protrusion And the regulating recess By engagement, characterized in that it comprises a thrust regulating means for regulating the thrust position of the feed holder along the axial direction of the transport rotation shaft such that the sensor and the sensor flag is not in contact.

  According to the present invention, it is possible to prevent inconvenience such as detection failure by reducing the backlash in the thrust direction of the feeding holder.

1 is a schematic cross-sectional view showing a laser beam printer as an image forming apparatus including a sheet feeding device according to an embodiment of the present invention. FIG. 3 is a schematic explanatory diagram of a sheet feeding apparatus according to the present embodiment. FIG. 3 is a top view of the sheet feeding device shown in a state viewed from the direction of an arrow U in FIG. 2. (A) is a figure which shows the feed holder seen from the feed tray side (lower side in FIG. 2), (b) is sectional drawing seen from the direction of arrow A in (a). The figure which shows the feeding holder state seen from the direction of arrow B in Fig.4 (a). The figure of the comparative example which shows the feeding holder seen from the feeding tray side. FIG. 3 is a block diagram illustrating a control system of the sheet feeding apparatus according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, it is assumed that the positional relationship between the top, bottom, left, and right is expressed with reference to the state of the image forming apparatus viewed from the front (the viewpoint in FIG. 1).

[Image forming apparatus]
An image forming apparatus 201 according to the present embodiment is an image forming apparatus using a full-color laser beam printer as an example, as schematically illustrated in FIG. The image forming apparatus 201 includes an image forming unit 201B that forms an image on a sheet P, a fixing unit 220 that fixes an image on the sheet P, and the like inside an apparatus main body 201A (printer main body) that is an image forming apparatus body. . Above the apparatus main body 201A, an image reading apparatus 202 that reads image data of a document is disposed in a posture in which the document placement surface is substantially horizontal. A discharge tray 230 serving as a discharge space for discharging the sheet P is provided between the image reading apparatus 202 and the apparatus main body 201A. The apparatus main body 201A is provided with a sheet feeding unit 201E that feeds the sheet P to the image forming unit 201B. The sheet feeding unit 201E includes sheet feeding devices 100A, 100B, 100C, and 100D that are disposed below the apparatus main body 201A, and a manual feeding device 100M that is disposed on the right side of the apparatus main body 201A. .

  The image forming unit 201B is a so-called four-drum full-color image forming unit that includes a laser scanner 210, four process cartridges 211, and an intermediate transfer unit 201C. These process cartridges form toner images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K). Each process cartridge 211 includes a photosensitive drum 212 as an image carrier, a charger 213 as a charging unit, a developing unit 214 as a developing unit, and a cleaner (not shown) as a cleaning unit. Above the image forming unit 201B, a toner cartridge 215 containing toner of each color is detachably attached to the apparatus main body 201A.

  In the present embodiment, the sheet feeding apparatuses 100A, 100B, 100C, and 100D have the same configuration, and hence are hereinafter collectively referred to as the sheet feeding apparatus 100. The image forming unit 201 </ b> B constitutes an image forming unit that forms an image on the sheet P sent out by the sheet feeding apparatus 100.

  The intermediate transfer unit 201C is configured by winding an intermediate transfer belt 216 as an intermediate transfer member around a driving roller 216a, a tension roller 216b, and the like, and is disposed above the four process cartridges 211. The intermediate transfer belt 216 is disposed so as to be in contact with the photosensitive drum 212 of each process cartridge 211 and is rotated counterclockwise (in the direction of the arrow Q) by a driving roller 216a driven by a driving unit (not shown). Driven by rotation. The intermediate transfer unit 201 </ b> C includes a primary transfer roller 219 that is in contact with the inner peripheral surface of the intermediate transfer belt 216 at a position facing each photoconductor drum 212, and between the intermediate transfer belt 216 and the photoconductor drum 212. A primary transfer portion T1 is formed as a nip portion. Further, the image forming unit 201B includes a secondary transfer roller 217 that contacts the outer peripheral surface of the intermediate transfer belt 216 at a position facing the driving roller 216a. As a nip portion between the secondary transfer roller 217 and the intermediate transfer belt 216, a secondary transfer portion T2 to which the toner image carried on the intermediate transfer belt 216 is transferred to the sheet P is formed.

  In each process cartridge 211 configured as described above, an electrostatic latent image is drawn on the surface of the photosensitive drum 212 by the laser scanner 210, and then toner is supplied from the developing device 214, thereby negative polarity. A toner image of each color charged is formed. These toner images are subjected to multiple transfer (primary transfer) sequentially to the intermediate transfer belt 216 at each primary transfer portion T1 by applying a positive transfer bias voltage to the primary transfer roller 219, and intermediate A full color toner image is formed on the transfer belt 216.

  In parallel with such a toner image forming process, the sheet P fed from the sheet feeding unit 201E is transported toward the registration roller pair 240, and skew correction is performed by the registration roller pair 240. The registration roller pair 240 conveys the sheet P to the secondary transfer portion T2 at a timing that matches the transfer timing of the full-color toner image formed on the intermediate transfer belt 216. The toner image carried on the intermediate transfer belt 216 is secondarily transferred onto the sheet P at the secondary transfer portion T2 by applying a positive transfer bias voltage to the secondary transfer roller 217.

  The sheet P to which the toner image has been transferred is heated and pressurized in the fixing unit 220, and the color image is fixed to the sheet P. The sheet P on which the image is fixed is discharged to the discharge tray 230 by the discharge roller pair 225 and stacked. When images are formed on both sides of the sheet P, the sheet P passes through the fixing unit 220 and is then switched back by a reversing roller pair 222 that can be rotated in the normal direction. Then, the sheet P is conveyed again to the image forming unit 201B via the reconveying path R, and an image is formed on the back surface.

[Sheet feeding device]
Next, the sheet feeding apparatus 100 according to the present embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic explanatory diagram of the sheet feeding apparatus 100. 3 is a top view of the sheet feeding apparatus 100 as seen from the direction of the arrow U in FIG.

  As shown in FIG. 2, the sheet feeding apparatus 100 includes a sheet storage 106 configured to be able to be attached to and pulled out from the apparatus main body 201 </ b> A, a sheet feeding unit 140, and a sheet feeding direction of the sheet feeding unit 140. And a drawing roller 121 disposed on the downstream side. A feeding frame 125 composed of an upper frame 125c and a lower frame 125d connected to each other is attached to the apparatus main body 201A. The feed frame 125 constitutes a support portion that rotatably supports a feed roller shaft (conveyance rotation shaft) 107a that supports the feed roller 107.

  The sheet feeding unit 140 includes a feeding unit portion 140a and a separation unit portion 140b that are integrally connected via a connecting means such as a screw. The feeding unit portion 140a is attached to the upper frame 125c, and the separation unit portion 140b is attached to the lower frame 125d.

  The feeding unit section 140 a includes a feed roller 107 as a transport roller and a pickup roller 102 as a feeding roller connected to the feed roller 107 via a feeding holder 111. The feed holder 111 holds the pickup roller 102 and is supported so as to be rotatable about the feed roller shaft 107a. The feed roller 107 is disposed on one end side (the right side in FIG. 4) in the axial direction of the feed roller shaft 107a (the direction of arrow E in FIG. 4A). The pickup roller 102 protrudes in parallel with the feed roller 107 from the feeding holder 111 and is supported at a position overlapping the feed roller 107 in the sheet feeding direction (see FIG. 5).

  The feed roller 107 is disposed downstream of the pickup roller 102 in the sheet feeding direction (the direction of arrow D). The feed roller 107 and the retard roller 108 are in contact with each other to constitute a separating and conveying means. The rotation operation (elevating operation) of the feeding holder 111 is interlocked with a link member (not shown), and is configured to move up and down in conjunction with operations when the sheet storage case 106 is attached to and pulled out from the apparatus main body 201A. The

  The separation unit 140b has a retard roller 108 as a separation roller. The retard roller 108 separates the sheets P fed by the pickup roller 102 one by one at a separation nip portion N formed in pressure contact with the feed roller 107. The separation unit 140b has a separation frame (not shown) that is rotatably supported by the lower frame 125d. The retard roller 108 is supported by the separation frame via a retard roller shaft 108a. A torque limiter 153 is provided on the retard roller shaft 108 a that supports the retard roller 108. The separation frame is urged upward by a spring (not shown) to press the retard roller 108 against the feed roller 107 to generate a nip pressure at the separation nip portion N.

  The retard roller 108 is attached to the retard roller shaft 108a via a torque limiter 153, without driving force being input to the retard roller shaft 108a. When the load applied from the feed roller 107 to the retard roller 108 via the sheet is equal to or greater than a predetermined torque value (limit value) of the torque limiter 153, the retard roller 108 is rotated along the sheet and is equal to or less than the predetermined torque value. The retard roller 108 stops.

  That is, the retard roller 108 receives a predetermined torque value via the torque limiter 153 or the like. The torque value is set larger than the friction force generated between the sheets due to the friction coefficient between the sheets and smaller than the friction force generated due to the friction coefficient between the sheet P and the feed roller 107. As a result, when one sheet P enters the separation nip N between the feed roller 107 and the retard roller 108 or when no sheet enters, the retard roller 108 rotates with the feed roller 107 (driven) Rotate. On the other hand, when the number of sheets P entering the separation nip N between the feed roller 107 and the retard roller 108 is two or more, the retard roller 108 stops the retard roller 108 without being rotated. Separate one by one. In this way, the sheets P fed by the pickup roller 102 are separated and conveyed one by one by the separation nip portion N.

  A sensor flag 111 f (see FIG. 4A) is attached to the feeding holder 111 at a position facing the sheet surface height detection sensor 110. On the upstream side in the sheet feeding direction of the pickup roller 102, a sheet surface height that is supported by the feeding frame 125 (see FIG. 4A) on the apparatus main body 201A and detects the sensor flag 111f on the feeding holder 111 side. A height detection sensor 110 (see also FIG. 7) is arranged. The sensor flag 111f constitutes a detected portion for detecting the rotation position of the feeding holder 111. The sheet surface height detection sensor 110 is fixed to the apparatus main body 201A side so that the height of the uppermost surface St of the sheets P stacked on the feeding tray 105 can be detected. The sheet surface height detection sensor 110 constitutes detection means for detecting a sensor flag (detected portion) 111f.

  In the present embodiment, the sensor flag 111f is provided in the feeding holder 111 and the sheet surface height detection sensor 110 is provided in the feeding frame 125. However, the other relationship may be reversed. That is, the same function can be achieved by providing the sheet surface height detection sensor 110 in the feeding holder 111 and providing the sensor flag 111f in the feeding frame 125.

  As shown in FIG. 2, the sheet storage case 106 includes a feeding tray 105 as a stacking means that can be lifted and supported by the apparatus main body 201 </ b> A so that a rotating base is pivotable, and a tray lifting and lowering that raises and lowers the feeding tray 105. Plate 109. The feed tray 105 is supported on the apparatus main body 201A side so as to be rotatable about the rotation shaft 105a. The tray elevating plate 109 is rotated about the rotation shaft 109a as a fulcrum when the driving force of the tray elevating motor 150 (see also FIG. 6) is transmitted via the drive transmission mechanism 151, and the feeding tray 105 is moved from below. Push up to lift up.

  As shown in FIGS. 2 and 3, side end regulating plates 104 </ b> F and 104 </ b> R are respectively arranged in the front-back direction in the drawing of the feeding tray 105, and the sheet feeding direction (indicated by the arrow D in the drawing of the feeding tray 105). The rear end regulating plate 120 is disposed on the upstream side in the direction). The side end regulating plates 104F and 104R are configured to approach and separate from each other via a rack and pinion mechanism (not shown), and the rear end regulating plates 120 are upstream and downstream in the sheet feeding direction (arrow D). It is supported so that it can move to the side. The sheets P stacked on the feeding tray 105 are positioned with their side portions and rear ends regulated by the side end regulating plates 104F and 104R and the rear end regulating plate 120, respectively.

  As shown in FIG. 3, a pickup roller shaft 102 a that supports the pickup roller 102 is rotatably attached to the feeding holder 111 at the upstream end in the sheet feeding direction (arrow D). In addition, a feed roller shaft 107a that supports the feed roller 107 is rotatably attached to the feeding holder 111 at a downstream end in the sheet feeding direction. Further, an idler shaft 113a that supports an idler gear 113 is rotatably attached to the feeding holder 111 between the pickup roller shaft 102a and the feed roller shaft 107a.

  As shown in FIGS. 3 and 4, the feed roller shaft 107 a is rotatably supported by the apparatus main body 201 </ b> A via the feeding frame 125. A drive transmission gear 128 is attached to the other end of the feed roller shaft 107a to which the feed roller 107 is attached at one end. Rotation from the feeding motor 117 (see FIG. 7) is transmitted to the drive transmission gear 128. The feed holder 111 is configured to be rotatable in the clockwise direction and the counterclockwise direction in FIG. 2 with the feed roller shaft 107a as a fulcrum. The rotation operation (elevating operation) of the feeding holder 111 is configured to move up and down in conjunction with the operation of mounting and pulling out the sheet storage case 106 on the apparatus main body 201A.

  A transmission gear 114 is attached to a position adjacent to the feed roller 107 on the feed roller shaft 107a, and a transmission gear 112 is attached to a position adjacent to the pickup roller 102 on the pickup roller shaft 102a. The transmission gear 114 meshes with the idler gear 113, and the idler gear 113 meshes with the transmission gear 112. The transmission gear 114 transmits the rotation of the feed roller shaft 107 a to the transmission gear 112 via the idler gear 113, thereby rotating the pickup roller 102 in the same direction as the feed roller 107.

  The feeding holder 111 is provided with a pickup pressing spring 116 that pressurizes (bias) the pickup roller 102 in the direction of the feeding tray 105 (downward in FIG. 2). In FIG. 2, the pickup pressure spring 116 is schematically described as a compression spring, but in this embodiment, the pickup pressure spring 116 is described as a torsion coil spring.

  In the sheet feeding apparatus 100 described above, when the tray lifting / lowering motor 150 is driven to raise the feeding tray 105, the uppermost surface St of the sheet P on the feeding tray 105 (on the stacking unit) comes into contact with the pickup roller 102. Push this up. When the pickup roller 102 reaches a predetermined height, the sheet surface height detection sensor 110 is turned on, and the tray lifting / lowering motor 150 is stopped by a signal from the control unit 149 (see FIG. 7) based on this, and the feeding tray 105 The ascending operation stops. Then, an optimum pressure for obtaining a feeding force is generated between the pickup roller 102 and the sheet P.

  The sheet surface height detection sensor 110 includes a photo interrupter. This detection sensor 110 is configured so that a sensor flag 111f (FIG. 4), which is a light shielding plate fixed to the feeding holder 111, enters and retreats between a light emitting / receiving unit (not shown). The rising state (the rising position of the uppermost surface St of the sheet) is detected. That is, when the sensor flag 111f moves back and forth with respect to the detection sensor 110, when the sensor flag 111f blocks the light path between the light emitting and light receiving portions of the photo interrupter, the output signal of the light receiving portion becomes a low level and the light path is blocked. When it is not, it becomes a high level. Therefore, it is possible to detect whether or not the uppermost surface St of the sheet P is at the reference position by setting the position where the output signal of the light receiving unit changes as the reference position.

[Support structure of feeding holder]
Next, the support structure of the feeding holder 111 in this embodiment will be described. 4A is a diagram showing the feeding holder 111 viewed from the feeding tray 105 side (that is, the lower side in FIG. 2). FIG. 4B is a cross-sectional view seen from the direction of arrow A in FIG. FIG. 5 is a diagram illustrating a state of the feeding holder 111 viewed from the direction of the arrow B in FIG.

  As described above, the feed holder 111 is rotatably supported with the feed roller shaft 107a as a fulcrum. The feed roller shaft 107a is supported by the bearing portion 126 and the bearing portion 127 with respect to the feed frame 125. Has been. The bearing portion 126 is supported by the side wall of the feeding frame 125, and the bearing portion 127 is supported by bearing support portions 125 a and 125 b in the feeding frame 125.

  On the feed roller shaft 107a, a drive transmission gear 128 and a retaining ring 129 are arranged in this order from the bearing portion 126 toward the feed roller shaft end portion 107t1. On the feed roller shaft 107a, a retaining ring 130, a gear 114, and the feed roller 107 are arranged in this order from the bearing portion 127 toward the feed roller shaft end portion 107t2. Therefore, the thrust position of the feed roller shaft 107 a is regulated with respect to the feed frame 125 by the retaining ring 129 and the retaining ring 130.

  On the other hand, the feeding holder 111 is fixed in a state where the gear side bearing fitting portion 111a is fitted to the cylindrical outer diameter portion of the bearing portion 126, and the roller side bearing fitting portion 111b is fixed to the cylindrical outer diameter portion of the bearing portion 127. And is supported by fitting. The thrust position of the feeding holder 111 is set in the thrust regulating groove (regulating recess) 131 formed in the feeding frame 125, and the thrust regulating rib (regulating) formed on the outer periphery of the gear side bearing fitting portion 111a of the feeding holder 111. (Projection) 111c is controlled by entering. Thrust restricting means 90 for restricting the thrust position of the feed holder 111 along the axial direction of the feed roller shaft (conveying rotation shaft) 107a by the engagement of the restricting convex portion and the restricting concave portion by the thrust restricting rib 111c and the thrust restricting groove 131. Is configured.

  A pickup pressurizing spring 116 composed of a torsion coil spring is disposed on the outer diameter of the cylindrical portion of the bearing portion 127 and between the bearing support portion 125a and the roller side bearing fitting portion 111b. One end of the spring end of the pickup pressure spring 116 is hung on the feeding frame 125, and the other is hung on the feeding holder 111. The pickup pressurizing spring 116 applies a torsional force so as to urge (pressurize) the pickup roller 102 in the direction toward the feeding tray 105.

  As shown in FIG. 5, a force is applied to the feeding holder 111 in the direction of the arrow Fa near the base of the feed roller 107 by the pickup pressing spring 116, and the feeding holder 111 is pushed down. As a result, the feeding holder 111 is lowered until the end (111a) of the feeding holder 111 abuts against a feeding holder stopper (rotation restricting portion) 132 provided on the feeding frame (supporting portion) 125. The feed holder stopper 132 is fitted on the other end side (left side in FIG. 4A) in the axial direction of the feed roller shaft 107a (in the direction of arrow E in FIG. 4A). By engaging the joint portion 111a, the lower limit position of the feeding holder 111 during rotation is regulated. In the circle in FIG. 5, the thrust restricting means 90 including the thrust restricting rib 111c and the like is shown enlarged.

  The thrust regulating rib (regulating convex portion) 111 c provided on the feeding holder 111 has a tapered shape that becomes thinner (thinner) toward the tip side that enters the thrust regulating groove (regulating concave portion) 131. That is, the thrust restricting rib 111 c has a tapered shape that gradually decreases toward the bottom 131 b of the thrust restricting groove 131. The thrust restricting groove 131 is formed to have a predetermined length in the front and back directions in FIG. 5 in the feeding frame 125 when viewed from the drive transmission gear 128 side in FIG. Accordingly, the thrust regulating rib 111c is also formed to have a predetermined length along the thrust regulating groove 131 in the front and back directions in FIG.

  Further, the thrust restricting rib 111c and the thrust restricting groove 131 are formed by the feed holder stopper 132 and the gear side bearing fitting portion (part) 111a in the axial direction of the feed roller shaft 107a (the direction of arrow E in FIG. 4A). Is arranged in the vicinity of the part to be engaged.

  In the present embodiment, the thrust regulating rib 111c is tapered and the inner wall surfaces 131a and 131a of the thrust regulating groove 131 are parallel to each other. However, the shape is not limited thereto. In other words, the thrust regulating rib 111c and the thrust regulating groove 131 can be configured to have a shape that gradually becomes relatively narrower or wider toward the tip. That is, the thrust restricting rib 111c can be formed in a rectangular cross section, and the inner wall surfaces 131a and 131a of the thrust restricting groove 131 can be gradually expanded toward the thrust restricting rib 111c.

  In this embodiment, the thrust restricting groove 131 is provided in the feeding frame 125 and the thrust restricting rib 111c is provided in the feeding holder 111. However, the other relationship may be reversed. In other words, a structure in which the thrust restricting rib 111 c is provided in the feeding frame 125 and the thrust restricting groove 131 is provided in the feeding holder 111 can be similarly functioned.

[Control system]
Next, the control system in the present embodiment will be described with reference to FIG. FIG. 7 is a block diagram illustrating a control system of the sheet feeding apparatus according to the present embodiment.

  As shown in FIG. 7, the present control system includes a control unit 149 as a control means having a CPU, a RAM, and a ROM. A sheet surface height detection sensor 110 is connected to an input port of the control unit (controller) 149, and a tray lifting / lowering motor 150 and a feeding motor 117 are connected to an output port.

  The sheet surface height detection sensor 110 detects the uppermost position of the sheet P stacked on the feeding tray 105 and outputs the signal to the control unit 149. The control unit 149 detects the height of the uppermost sheet based on a signal from the sheet surface height detection sensor 110, and when the height is low, drives the tray lifting / lowering motor 150 to drive the transmission mechanism 151 ( The feed tray 105 is lifted through (see FIG. 2).

  The feed motor 117 is driven by the control of the control unit 149 and transmits the rotation to the drive transmission gear 128. As a result, the feed roller 107 is rotated via the feed roller shaft 107a, and the pickup roller 102 is rotated in the same direction as the feed roller 107 via the transmission gear 114, idler gear 113, and transmission gear 112 (FIG. ), (B)).

  Next, the operation of the sheet feeding apparatus 100 in the present embodiment will be described.

  That is, when the feed holder 111 rotates, the feed holder 111 abuts and is held against the feed holder stopper 132 on the feed frame 125 side. On the other hand, the pickup pressurizing spring 116 near the base of the feed roller 107 in the direction of arrow Fa. The power of. Therefore, the feed holder 111 is likely to be twisted and deformed with the feed holder stopper 132 as a fulcrum, and the thrust regulating rib 111c is also tilted along with the twist deformation.

  However, in the present embodiment, since the tip of the thrust regulating rib 111c is tapered, the tip side of the thrust regulating rib 111c does not come into strong contact with the inner wall surfaces 131a and 131a of the thrust regulating groove 131.

  Here, the comparative example of the structure which does not have the thrust control rib 111c and the thrust control groove | channel 131 in this embodiment is demonstrated with reference to FIG. FIG. 6 is a view of a comparative example showing the feeding holder viewed from the feeding tray side. In this comparative example, the same members as those in the above-described embodiment are denoted by the same reference numerals, and the description of the members having the same configuration and function is omitted.

  Consider a case in which the pickup roller 102 is disposed in the feeding holder 111 and is moved up and down with the feed roller shaft 107a as a fulcrum with respect to the above-described embodiment. That is, as shown in FIG. 6, the axial restriction of the feed roller shaft 107a, which is the rotation shaft of the feed holder 111, is controlled by the first bearing portion 126 and the second bearing portion provided on the feed roller shaft 107a. 127 is supported. The thrust regulation of the feed roller shaft 107a with respect to the feeding frame 125 arranged on the apparatus main body 201A side is performed as follows. That is, it is performed via the first bearing portion 126 and the second bearing portion 127 that support the feed roller shaft 107a, the drive transmission gear 128 that rotationally drives the feed roller shaft 107a, the retaining rings 129 and 130, and the like.

  In this configuration, since the raising and lowering operation of the feeding holder 111 is performed smoothly, it is sufficient that the feeding holder 111 is not clogged in the thrust direction and the sliding resistance is not increased even if the dimensions of parts related to thrust regulation vary. Secure clearance. Therefore, the play in the thrust direction with respect to the feeding frame 125 of the feeding holder 111 inevitably increases. Therefore, the sensor flag 111f that detects the raising / lowering position of the feeding holder 111 has a large play in the thrust direction with respect to the sheet surface height detection sensor 110 on the feeding frame 125 side. For this reason, the sensor flag 111f may come into contact with the sheet surface height detection sensor 110 on the feeding frame 125 side, which may cause inconvenience such as detection failure or damage.

  In contrast to such a comparative example, the present embodiment has a thrust regulating rib 111c and a thrust regulating groove 131 provided in the feeding holder 111 and the feeding frame 125, respectively. And it has the thrust control means 90 which controls the thrust position of the feed holder 111 along the axial direction of the feed roller shaft 107a by the engagement of the thrust control rib 111c and the thrust control groove 131. For this reason, by reducing the backlash in the thrust direction of the feeding holder 111 with respect to the feeding frame 125, the sheet surface height detection sensor 110 and the sensor flag 111f are protected from contact with each other, and inconvenience such as detection failure is caused. It becomes possible not to generate.

  Further, in the present embodiment, the thrust restricting rib 111c and the thrust restricting groove 131 have a shape that gradually becomes thinner or expands relatively toward the tip. For this reason, even if torsional deformation of the feeding holder 111 occurs, it is possible to avoid a phenomenon in which the thrust restricting rib 111c is twisted with the inner wall surfaces 131a and 131a of the thrust restricting groove 131 to increase the sliding resistance. As a result, it is possible to prevent the lifting operation failure and the pressurization failure of the pickup roller 102 to the sheet P.

  As described above, even when the sensor flag 111f for detecting the raising / lowering position of the feeding holder 111 is arranged on the feeding holder 111 side, the backlash in the thrust direction with respect to the feeding frame 125 can be prevented from becoming large. . Then, when the sheet surface height detection sensor 110 is arranged on the feeding frame 125, it is possible to prevent the sensor flag 111f from touching and causing a detection failure or breakage.

  In the present embodiment, the feed roller 107 is disposed on one end side in the axial direction of the feed roller shaft 107a. The pickup roller 102 is supported at a position that protrudes in parallel with the feed roller 107 from the feeding holder 111 and overlaps the feed roller 107 in the sheet feeding direction. Then, the feeding frame 125 engages the gear-side bearing fitting portion 111a of the feeding holder 111 with the other end side in the axial direction of the feed roller shaft 107a, thereby setting the lower limit position of the feeding holder 111 during rotation. It has a feeding holder stopper 132 to be regulated. Further, the thrust restricting rib 111c and the thrust restricting groove 131 are disposed in the vicinity of a portion where the feed holder stopper 132 and the gear side bearing fitting portion 111a are engaged in the axial direction of the feed roller shaft 107a. With this configuration, it is possible to effectively support the load caused by the twist of the feeding holder 111 due to the load of the pickup roller 102 and the feed roller 107.

  In this embodiment, the electrophotographic image forming apparatus 201 has been described. Instead, for example, an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from a nozzle. It can also be used.

  90 ... Thrust restricting means / 100 ... Sheet feeding device / 102 ... Pickup roller (feeding roller) / 105 ... Feeding tray (stacking means) / 107 ... Feed roller (conveying roller) / 107a ... Feed roller shaft (conveying rotation) Shaft) / 108 ... retard roller (separation roller) / 110 ... sheet surface height detection sensor (detection means) / 111 ... feed holder / 111a ... gear side bearing fitting portion (part of feed holder) / 111c ... Thrust restriction rib (regulation convex part) / 111f ... sensor flag (detected part) / 125 ... feed frame (support part) / 131 ... thrust restriction groove (regulation recess) / 132 ... feed holder stopper (rotation restriction part) ) / 201 Image forming apparatus / 201B Image forming unit (image forming unit) / D Sheet feeding direction / E ... Axial direction of feed roller shaft (Axial direction of conveyance rotation shaft) / N ... separation nip / P ... sheet

Claims (10)

A stacking means on which sheets are stacked;
A feeding roller for feeding sheets on the stacking means;
A conveying roller that is arranged downstream of the feeding roller in the sheet feeding direction and conveys the sheet ;
A transport rotating shaft that supports the transport roller;
And feed frame for rotatably supporting the front Ki搬 feed rotation axis,
Holding the feed roller, and the feeding holder pivotable the transport rotation shaft as a fulcrum,
A sensor flag provided in the feeding holder for detecting the position of the feeding holder;
A sensor provided on the feeding frame for detecting the sensor flag;
It has a restricting protrusion portion provided on either one of the feeding holder and the feeding frame, and a regulating recess provided in the other of the feed holder and the feeding frame, the restricting projection A thrust restricting means for restricting a thrust position of the feeding holder along the axial direction of the transport rotation shaft so that the sensor flag and the sensor do not come into contact with each other due to the engagement between the portion and the restriction recess.
A sheet feeding apparatus characterized by that. The restriction convex part has a tapered shape that gradually becomes thinner toward the tip side entering the restriction concave part,
The sheet feeding apparatus according to claim 1.   The restriction recess has two inner wall surfaces that face each other in the axial direction and are provided in parallel with each other.
  The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus.   The restriction recess has two inner wall surfaces facing each other in the axial direction,
  The two inner wall surfaces have shapes that move away from each other toward the regulating convex side.
  The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus. The transport roller is disposed on one end side in the axial direction of the transport rotation shaft,
The feeding roller is supported at a position protruding in parallel with the conveying roller from the feeding holder and overlapping the conveying roller in the sheet feeding direction,
The feed holder is configured to regulate a lower limit position of the feed holder during rotation by engaging a part of the feed holder with the other end side in the axial direction of the transport rotation shaft. Have
The restricting convex portion and the restricting concave portion are disposed in the vicinity of a portion where the rotation restricting portion and the part are engaged in the axial direction of the transport rotation shaft.
The sheet feeding device according to any one of claims 1 to 4, wherein the sheet feeding device is provided.   The sensor is composed of a photo interrupter,
  The position of the feeding roller is detected in response to the sensor flag entering and retracting between the light emitting unit and the light receiving unit of the photo interrupter.
  The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus.   A separation nip portion formed in pressure contact with the conveying roller, and a separation roller that separates the sheets fed by the feeding roller one by one,
  The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.   The restriction convex portion is a rib provided on the feeding holder,
  The restriction recess has a groove provided in the feeding frame.
  The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.   A pressure spring that pressurizes the feeding roller in the direction of the stacking unit is disposed in the feeding holder.
  The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device. A sheet feeding device according to any one of claims 1 to 9 ,
Image forming means for forming an image on the sheet fed by the sheet feeding device,
An image forming apparatus.

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