JP5606161B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to a configuration of a sheet separating unit that separates sheets fed by a feeding roller one by one.

  Some conventional image forming apparatuses form an image on a sheet using, for example, an electrophotographic image forming system. Such an image forming apparatus directs a sheet stored in a paper feed cassette toward an image forming unit. A sheet feeding device for feeding is provided. The sheet feeding device prevents the sheet from being double-fed by pressing the sheet separating member, which is a friction member such as a separation pad, against the feeding roller, and feeds only the uppermost sheet one by one. Some have a sheet separation unit.

  FIG. 11 is a diagram illustrating a configuration of a sheet feeding apparatus including such a conventional sheet separating unit. In FIG. 11, 15 is a feeding roller for feeding sheets P placed on the intermediate plate 13 one by one, 16 is a feeding roller provided coaxially with the feeding roller 15, and 17 is a separation pad. . The separation pad 17 which is this separation member is attached to the rotation end of the holder 17A with the rotation shaft 17a as a fulcrum, and by urging the holder 17A toward the feeding roller by the separation pad spring 18, It is brought into pressure contact with the feed roller 15 or the feed roller 16. A sheet conveying roller pair 21 includes a conveying roller 19 and a conveying roller 20.

  In such a sheet feeding apparatus, when the sheet feeding operation is started, the sheets P are fed by the feeding roller 15 and then separated one by one by the separation pad 17. Thereafter, the sheet P is sandwiched between the feeding roller 16 and the separation pad 17 and conveyed downstream so as to be pulled out by the sheet conveying roller pair 21.

  Here, for example, in a small laser beam printer, the path after the sheet feeding is provided by providing the sheet conveying roller pair 21 on the feeding roller side with respect to the tangent line A of the contact portion between the feeding roller 16 and the separation pad 17. Is made compact. However, when configured in this way, the drawing direction of the sheet P is a direction around the feeding roller 16.

  That is, when the sheet P is conveyed by the sheet conveying roller pair 21 while being sandwiched between the feeding roller 16 and the separation pad 17, the drawing direction of the sheet P is as shown in FIG. The direction of the straight line B connects the contact portion 17 and the sheet conveying roller pair 21. Thereby, when the sheet conveying roller pair 21 pulls out the sheet P, a force F in the straight line B direction acts on the feeding roller 16 by the sheet P. This force F is decomposed into a force Ft in the tangential A direction and a force Fn in the normal C direction.

  Here, since the force Fn in the normal direction is the direction toward the feeding roller center 16a, when the sheet P is conveyed and pulled out by the sheet conveying roller pair 21, the feeding roller 15 passes through the feeding roller 16 by the sheet P. And a support portion (not shown) that supports the feeding roller 16 is pressed. As a result, a support portion (not shown) vibrates integrally with the feeding roller 16, and noise may occur due to the vibration.

  In order to reduce the occurrence of noise during sheet feeding, conventionally, for example, a leaf spring that urges the holder 17A toward the feeding roller is added, and the separation pad is always pressed against the feeding roller. There is one that suppresses vibration (see Patent Document 1). In addition, there is one in which the pressure contact between the feeding roller and the separation pad is released when the sheet is conveyed by the sheet conveying roller pair 21 (see Patent Document 2).

JP-A-7-133303 Japanese Patent Laid-Open No. 5-208747

  By the way, in such a conventional image forming apparatus, in the method of suppressing the vibration by the leaf spring, the sheet feeding performance may be lowered by the pressure of the leaf spring. Further, in the method of releasing the pressure contact between the feeding roller and the separation pad, the separation performance is deteriorated and there is a possibility that double feeding occurs. That is, in the method of suppressing vibration by the leaf spring and the method of releasing the pressure contact between the feeding roller and the separation pad, noise during sheet feeding can be suppressed, but the separation feeding performance is lowered.

  Accordingly, the present invention has been made in view of such a current situation, and provides an image forming apparatus capable of suppressing generation of noise during sheet feeding without affecting the sheet separation and feeding performance. It is intended to do.

The present invention provides a feed roller that has a notch in the peripheral surface and feeds a sheet by the peripheral surface, a feed roller formed with a smaller diameter than the peripheral surface of the feed roller, and the feed roller. A sheet separating member that is in pressure contact; and a sheet conveying roller pair that is provided in a curved sheet conveying path provided downstream of the feeding roller in a sheet feeding direction and that conveys a sheet fed by the feeding roller. provided, the fed sheet reaches the sheet conveying roller pair, wherein the cutout portion of the feed roller is opposed to the sheet separating member, sandwiching the sheet between the feeding roller and the sheet separating member In the image forming apparatus configured as described above, a sheet separating unit that includes the feeding roller and the sheet separating member and separates a sheet fed by the feeding roller, and the curved sheet carrying Constitute the road, the arranged sheet leading edge of the sheet which has passed through the separation unit and the abutment position, a guide member for contact with the sheet guide toward the sheet conveying roller pair, the sheet separating unit and said sheet conveying A projecting member provided between the pair of rollers so as to be movable to a projecting position close to the guide member and a retracted position that does not interfere with sheet feeding by the feeding roller; and the projecting member is moved to the retracted position and the projecting position. A moving portion that is moved to a position before the sheet fed by the feeding roller reaches the pair of sheet conveying rollers, and the protruding portion is positioned at the retracted position by the moving portion and fed. wherein when the sheet reaches the sheet transport rollers, the protrusion member by the moving unit, is moved to the projecting position from the retracted position, and the feeding roller Shi It is characterized in that for pressing the sheet to be conveyed in a state of being sandwiched by preparative separation member by the sheet conveying roller pair to the guide member.

  As in the present invention, when the sheet reaches the pair of sheet conveying rollers, the sheet pressing member is pressed against the guide member side by pressing the sheet sandwiched between the feeding roller and the separating member, thereby pressing the feeding roller with the sheet separating member. Can be reduced. As a result, the generation of noise during sheet feeding can be suppressed without affecting the sheet separation and feeding performance.

1 is a diagram illustrating a schematic configuration of an electrophotographic printer which is an example of an image forming apparatus according to a first embodiment of the present invention. The figure explaining the structure of the said sheet feeding apparatus. The perspective view of the said sheet feeding apparatus. The figure which shows the effect | action of the force at the time of sheet feeding of the said sheet feeding apparatus. FIG. 6 is a diagram illustrating a configuration of a sheet feeding device provided in an image forming apparatus according to a second embodiment of the present invention. The perspective view of the said sheet feeding apparatus. The figure which shows the effect | action of the force at the time of sheet feeding of the said sheet feeding apparatus. FIG. 10 is a diagram illustrating a configuration of a sheet feeding device provided in an image forming apparatus according to a third embodiment of the present invention. The perspective view of the said sheet feeding apparatus. The figure which shows the effect | action of the force at the time of sheet feeding of the said sheet feeding apparatus. FIG. 6 is a diagram illustrating a schematic configuration of a conventional sheet feeding apparatus. The figure which shows the effect | action of the force at the time of sheet feeding of the conventional sheet feeding apparatus.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an electrophotographic printer which is an example of an image forming apparatus according to a first embodiment of the present invention. In FIG. 1, 50 is a printer, 51 is a printer main body, 52 is provided in the printer main body 51, an image forming unit that forms an image by electrophotography, and 1 is a sheet feeding that feeds a sheet P to the image forming unit 52 Device.

  The image forming unit 52 includes a photosensitive drum 2 that forms a toner image, a charging roller 3 that uniformly charges the surface of the photosensitive drum 2, a developing sleeve 4, a toner container 5, and the like, and is attached to and detached from the printer main body 51. A process cartridge 53 that is freely mounted is provided. Further, a transfer roller 6 for transferring the toner image formed on the photosensitive drum 2 to the sheet P is provided.

  The sheet feeding apparatus 1 has a sheet feeding tray (not shown) provided in the printer main body 51 and a circumferential surface for feeding sheets P stacked and stored on a middle plate 13 rotatably provided on the sheet feeding tray. A half-moon shaped sheet feeding roller 15 having a notch 15A is provided. Further, the feeding roller 16 having a smaller diameter than the feeding roller 15 provided coaxially with the shaft 15a of the sheet feeding roller (hereinafter referred to as the feeding roller) 15 and the sheet P fed by the feeding roller 15 are fed. A sheet separation unit 54 for separation is provided.

  Here, the feeding roller 15 can feed the sheets P one by one from the intermediate plate 13 urged toward the feeding roller by the spring 13a by one rotation control. The feed roller 15 and the feed roller 16 are rotatably supported by a support unit (not shown). In FIG. 1, reference numeral 21 denotes a sheet conveying roller pair provided on the downstream side of the sheet separating unit 54 in the sheet conveying direction.

  The sheet separation unit 54 includes a separation pad 17 that is a sheet separation member that is in pressure contact with the feeding roller 15, and a separation pad holder 17 </ b> A that holds the separation pad 17 in pressure contact with the feeding roller 15. The separation pad holder 17A is rotatably supported by the printer main body 51 by a rotation shaft 17a upstream of the separation pad 17 in the sheet feeding direction, and is urged toward the feeding roller 15 by the separation pad spring 18. Has been. In this embodiment, the separation pad 17 is urged by the separation pad spring 18 so as to come into pressure contact with the feeding roller 15 when the sheet is fed by the feeding roller 15, and the sheet is fed by the feeding roller 15. After being pushed, it is urged to press against the feeding roller 16.

  Next, an image forming operation in the printer 50 having such a configuration will be described. When a print start signal is input after the sheet P to which toner is transferred is set on the intermediate plate 13 of the paper feed tray, a driving force is applied by a driving gear train (not shown), and the feeding roller 15 rotates once. While being driven, the sheet conveying roller pair 21 and the photosensitive drum 2 are driven.

  Here, when the feed roller 15 rotates, a feed cam (not shown) that regulates the position of the rotatable intermediate plate 13 is attached to the shaft 15a of the feed roller 15. It rotates with the feeding roller 15. Then, the intermediate plate 13 rotates upward in conjunction with the rotation of the sheet feeding cam and presses the sheet P against the feeding roller 15. As a result, first, the uppermost sheet P <b> 1 of the sheets P set on the intermediate plate 13 is sent out by friction with the feeding roller 15.

  On the other hand, simultaneously with the rotation of the feeding roller 15, the uppermost sheet P 1 is separated from the next sheet by the separation pad 17 by the separation pad 17 biased by the separation pad spring 18. Thus, only the uppermost sheet P1 is conveyed to the image forming unit 52 by the sheet conveying roller pair 21. Note that immediately before the rotation of the feeding roller 15 is completed, the sheet feeding cam pushes the intermediate plate 13 down to the sheet feeding standby position. When the sheet P1 reaches the sheet conveying roller pair 21, the feeding roller 15 is in a state in which the notch 15A faces the sheet P1, is separated from the sheet P1, and is fed so as to prevent the sheet P from being double-fed. The separation pad 17 comes into contact with the feeding roller 16. That is, when the sheet P1 reaches the sheet conveying roller pair 21, the notch 15A of the feeding roller 15 faces the separation pad 17, and the sheet P1 is sandwiched between the feeding roller 16 and the separation pad 17. It becomes a state to do.

  Next, when the sheet P1 is conveyed by the sheet conveying roller pair 21, the laser exposure device 7 irradiates the photosensitive drum 2 whose surface is uniformly charged by the charging roller 3 with a laser beam at a predetermined timing. An electrostatic latent image is formed on the photosensitive drum 2. Thereafter, the developing sleeve 4 rotates. As a result, the toner T filled in the toner container 5 is appropriately charged with the rotation of the developing sleeve 4 and then supplied to the photosensitive drum 2, and the electrostatic latent image on the photosensitive drum 2 is supplied. Adhere to. As a result, the latent image is developed and visualized as a toner image. Thereafter, the visualized toner image on the photosensitive drum 2 is transferred onto the sheet P 1 by the transfer roller 6. Note that the untransferred toner remaining on the photosensitive drum 2 without being transferred to the sheet P1 is stored in a waste toner container 27 provided in the process cartridge 53 by a cleaning blade (not shown). Further, the photosensitive drum 2 whose surface has been cleaned in this manner repeatedly enters the next image forming process.

  Next, the sheet P1 on which the toner image is formed is conveyed to a fixing device 10 including a heating device 8 and a pressure roller 9, and is heated and pressed by the fixing device 10, whereby the toner is formed on the sheet P1. The image is permanently fixed. After the image is fixed in this manner, the sheet P1 is sandwiched and conveyed between the paper discharge roller 11 and the paper discharge roller 12, and is discharged to the discharge stack tray 26.

  FIG. 2 is a diagram illustrating the configuration of the sheet feeding apparatus 1, and FIG. 3 is a perspective view of the sheet feeding apparatus 1. 2 and 3, reference numeral 22 denotes a first sheet guide member, and reference numeral 23 denotes a second sheet guide member. The first sheet guide member 22 is a guide member that is provided on the downstream side of the sheet separating unit 54 in the sheet feeding direction and constitutes a curved sheet conveyance path R that guides the separated sheet to the sheet conveyance roller pair 21. .

  The first sheet guide member 22 is provided between the feeding roller 15 and the sheet conveying roller pair 21 with high accuracy with respect to the nip portion of the sheet conveying roller pair 21, and the separation pad 17 for the fed sheet P. Guide the side. The second sheet guide member 23 that is a protruding member is provided between the feeding roller 15 and the sheet conveying roller pair 21 and guides the feeding roller 16 side of the fed sheet P. Here, the sheet conveying roller pair 21 is constituted by conveying rollers 19 and 20, and the nip portion of the feeding roller 16 is in contact with the feeding roller 16 and the separation pad 17 as shown in FIG. 2. It is provided closer to the feeding roller than the tangent line (extension line) A drawn to the contact surface.

  During operation of the feed roller 15, the second sheet guide member 23 is held at the retracted position E on the feed roller side from the tangent line A, which is indicated by a solid line in FIG. Further, when the sheet feeding operation of the feeding roller 15 is completed, the second sheet guide member 23 is located on the tangent line A (extended line) from the retracted position E or indicated by the broken line, or on the first sheet guide member 22 from the tangent line A. It moves to the projecting position D projecting in the direction of approaching. When moving to the protruding position D in this way, a gap is formed between the second sheet guide member 23 and the first sheet guide member 22 so as not to prevent sheet feeding.

  Reference numeral 28 denotes a solenoid that constitutes a moving unit that moves the second sheet guide member 23 movable to the retracted position E or the projecting position D close to the second sheet guide member 22 to the retracted position E or the projecting position D. When the solenoid 28 is turned on, the second sheet guide member 23 is held at the retracted position E, and when it is turned off, the second sheet guide member 23 moves to the protruding position D. In the present embodiment, the solenoid 28 is turned on while the feeding roller 15 is in operation, and turned off when the feeding roller 15 finishes the operation. That is, the solenoid 28 is turned ON / OFF synchronously using the control of the feeding roller 15, and accordingly, the second sheet guide member 23 moves to the retracted position E or the protruding position D.

  In the sheet feeding apparatus 1 having such a configuration, when the feeding roller 15 rotates, the sheet P placed on the intermediate plate 13 is fed out by the feeding roller 15 and is fed by the separation pad spring 18. The sheets are separated one by one by the separation pad 17 pressed against the sheet. The separation pad 17 is generally made of urethane rubber or the like containing cork, and the surface friction coefficient, contact angle, and shape of the top sheet and only one sheet for each feeding operation. It is adjusted so that it can be transported. Further, after the sheet P is fed, the separation pad 17 presses against the feeding roller 16 and sandwiches the sheet P.

  Next, the fed sheet P is guided by the first sheet guide member 22 and is fed to the sheet conveying roller pair 21. When the conveyance of the sheet P is started by the sheet conveyance roller pair 21, the sheet P is conveyed so as to be pulled out while being held between the separation pad 17 and the feeding roller 16.

  At this time, as described above, the sheet conveying roller pair 21 is closer to the feeding roller than the tangent line A drawn to the contact surface of the feeding roller 16 at the contact portion between the feeding roller 16 and the separation pad 17. Is provided. In this case, the drawing direction of the sheet P is a direction around the feeding roller 16. Here, when there is no second sheet guide member 23 that guides the feeding roller 16 side of the sheet P, a force that presses the separation pad 17 against the feeding roller 16 is generated when the sheet conveying roller pair 21 conveys the sheet P. Then, the sheet P is pulled out. In such a case, a support portion (not shown) vibrates integrally with the feeding roller 16, and noise may be generated by this vibration.

  However, in the present embodiment, when the feeding roller 15 finishes operating and the sheet P reaches the sheet conveying roller pair 21 and begins to be conveyed, the solenoid 28 is turned OFF, and as shown in FIG. The two-sheet guide member 23 moves from the retracted position E to the protruding position D. As a result, the sheet P is pressed by the second sheet guide member 23 and moves to the first sheet guide member side. Accordingly, the sheet P is pulled out in the direction in which the feeding roller 16 and the separation pad 17 are in contact with each other. It becomes the direction of the straight line B1 which connects the front-end | tip of the 2 sheet | seat guide member 23. FIG. That is, when the sheet P is conveyed by the sheet conveying roller pair 21 while being sandwiched between the feeding roller 16 and the separation pad 17, the drawing direction of the sheet P is more than the tangent line A due to the movement of the second sheet guide member 23. The direction is the straight line B1 on the separation pad side (sheet separation member side).

  When the drawing direction becomes the direction of the straight line B1 in this way, when the sheet conveying roller pair 21 pulls out the sheet P, a force F1 in the direction of the straight line B1 acts on the separation pad 17 by the sheet P. This force F1 is decomposed into a force Ft1 in the tangential A direction and a force Fn1 in the normal C direction, but this normal direction force Fn1 is away from the feeding roller center 16a.

  For this reason, when the sheet conveying roller pair 21 conveys the sheet P so as to pull out the sheet P, the separation pad 17 is not conveyed while being pressed against the feeding roller 16 by the pulling force of the sheet P. As a result, the support portion does not vibrate integrally with the feeding roller 16, and the generation of noise can be prevented.

  Until the sheet P is conveyed to the sheet conveying roller pair 21, the second sheet guide member 23 is held at the retracted position E by the solenoid 28 as shown in FIG. There is no collision with the member 23. Further, when the feeding roller 15 feeds the sheet P, the second sheet guide member 23 does not come into contact with the sheet P, so that the second sheet guide member 23 does not become a feeding resistance and is good. Feeding performance can be realized.

  As described above, in the present embodiment, when the sheet is conveyed by the sheet conveying roller pair 21, the second sheet guide member 23 is moved to the protruding position and the sheet P is pressed toward the first sheet guide member. I am doing so. Thereby, the drawing direction of the sheet is changed to the separation pad side, and the force for pressing the separation pad 17 against the feeding roller 16 by the drawing of the sheet P is not generated. For this reason, it is possible to reduce the generation of noise when the sheet conveying roller pair 21 conveys the sheet while being sandwiched between the separation pad 17 and the feeding roller 16.

  Next, a second embodiment of the present invention will be described. FIG. 5 is a diagram illustrating the configuration of the sheet feeding device provided in the image forming apparatus according to the present embodiment, and FIG. 6 is a perspective view thereof. 5 and 6, the same reference numerals as those in FIGS. 2 and 3 described above indicate the same or corresponding parts.

  5 and 6, reference numeral 24 denotes a second sheet guide member. In the present embodiment, the second sheet guide member 24 is a roller shaft 19 a of the conveying roller 19 on the feeding roller side of the sheet conveying roller pair 21. Is pivotally supported by the shaft. The first sheet guide member 22 is arranged with high accuracy with respect to the sheet conveying roller pair 21 in order to smoothly introduce the sheet into the nip portion of the sheet conveying roller pair 21. Therefore, if the second sheet guide member 24 is pivotally supported by the conveying roller 19, the second sheet guide member 24 can be disposed with respect to the first sheet guide member 22 with high accuracy. Further, a boss 24 a is projected from the side surface of the second sheet guide member 24.

  Reference numeral 40 denotes a feeding shaft to which the feeding roller 15 is fixed, and a cam 30 which is a moving unit that moves the second sheet guide member 24 to the retracted position E or the protruding position D on the feeding shaft 40. Is provided. The feed roller 15 and the cam 30 are controlled to rotate once by the feed shaft 40. Here, the cam 30 has a continuous cam outer shape 30a. With this cam outer shape 30a, the boss 24a is moved away from the feeding shaft 40 while the feeding roller 15 is operating. When the operation of 15 is finished, the boss 24a can be moved closer to the feeding shaft 40. Reference numeral 41 denotes a pressing member disposed in order to cause the boss 24a to continuously follow the cam outer shape 30a.

  In the sheet feeding apparatus 1 having such a configuration, when the feeding roller 15 rotates, the sheet P is fed out and separated one by one by the separation pad 17 pressed against the feeding roller 15 by the separation pad spring 18. Is done. In addition, after feeding the sheet P, the separation pad 17 presses against the feeding roller 16 and sandwiches the sheet P. Next, the fed sheet P is guided by the first sheet guide member 22 and fed to the sheet conveying roller pair 21, and thereafter, is sandwiched between the separation pad 17 and the feeding roller 16 by the sheet conveying roller pair 21. It is transported as it is pulled out.

  Here, when the sheet P starts to be conveyed by the sheet conveying roller pair 21 in this way, the second sheet guide member 24 brings the boss 24a closer to the feeding shaft 40 by the cam outer shape 30a of the cam 30 pressed against the boss 24a. So as to move continuously following. Accordingly, as shown in FIG. 7, the second sheet guide member 24 moves from the retracted position E to the tangent line A or to the projecting position D projecting to the first sheet guide member side from the tangent line A. Press toward the first sheet guide member.

  For this reason, when the sheet P is pulled out by the sheet conveying roller pair 21, the drawing direction of the sheet P is a straight line B <b> 2 that connects the contact portion of the feeding roller 16 and the separation pad 17 and the tip of the second sheet guide member 24. Become a direction. When the drawing direction is the direction of the straight line B2, the force P2 in the direction of line B2 acts on the separation pad 17 by the sheet P when the sheet conveying roller pair 21 pulls out the sheet P. This force F2 is decomposed into a force Ft2 in the tangential line A direction and a force Fn2 in the normal line C direction, and this normal direction force Fn2 is in a direction away from the feeding roller center 16a.

  For this reason, when the sheet conveying roller pair 21 conveys the sheet P while being held between the separation pad 17 and the feeding roller 16, it can be conveyed while pressing the separation pad 17 against the feeding roller 16 by the pulling force of the sheet P. Disappear. As a result, the support portion does not vibrate integrally with the feeding roller 16, and the generation of noise can be prevented.

  Until the sheet P is conveyed to the sheet conveying roller pair 21, the second sheet guide member 24 is held at the retracted position E by the cam 30, as shown in FIG. There is no collision with the member 24. Further, when the feeding roller 15 feeds the sheet P, the second sheet guide member 24 does not come into contact with the sheet P, so that the second sheet guide member 24 does not become a feeding resistance and is good. Feeding performance can be realized.

  As described above, in the present embodiment, the second sheet guide member 24 is pivotally supported by one of the conveyance rollers 19 of the sheet conveyance roller pair 21, and the second sheet guide member 24 is pivotally supported by the feeding shaft 40. The cam 30 is moved to the retracted position E or the protruding position D. The second sheet guide member 24 can be accurately arranged with respect to the first sheet guide member 22 by pivotally supporting the second sheet guide member 24 on the conveying roller 19 in this way.

  For this reason, the second sheet guide member 24 can be protruded to the vicinity of the first sheet guide member 22, and the generation of noise can be further prevented. Further, since the second sheet guide member 24 is moved by the cam 30 fixed to the feeding shaft 40, the movement timing and the sheet feeding timing of the second sheet guide member 24 can be accurately adjusted with a simple and low-cost configuration. Can be set.

  Next, a third embodiment of the present invention will be described. FIG. 8 is a diagram illustrating the configuration of the sheet feeding device provided in the image forming apparatus according to the present embodiment, and FIG. 9 is a perspective view thereof. 8 and 9, the same reference numerals as those in FIGS. 5 and 6 described above indicate the same or corresponding parts.

  8 and 9, reference numeral 25 denotes a second sheet guide member. In the present embodiment, the second sheet guide member 25 is a roller shaft 19 a of the conveyance roller 19 on the feeding roller side of the sheet conveyance roller pair 21. Is pivotally supported by the shaft. A driven roller 25b, which is a rotating body, is disposed at the distal end of the second sheet guide member 25. When the second sheet guide member 25 rotates toward the first sheet guide member 22, the first The driven roller 25b is positioned closest to the sheet guide member 22. Thus, when the second sheet guide member 25 moves to the protruding position D, the driven roller 25b presses the sheet.

  In the sheet feeding apparatus 1 having such a configuration, when the feeding roller 15 rotates, the sheet P is fed out and separated one by one by the separation pad 17 pressed against the feeding roller 15 by the separation pad spring 18. Is done. In addition, after feeding the sheet P, the separation pad 17 is pressed against the feeding roller 16 to sandwich the sheet P.

  Next, the fed sheet P is guided by the first sheet guide member 22 and fed to the sheet conveying roller pair 21, and thereafter, is sandwiched between the separation pad 17 and the feeding roller 16 by the sheet conveying roller pair 21. It is transported as it is pulled out. Here, when the sheet P starts to be conveyed by the sheet conveying roller pair 21 in this way, the second sheet guide member 25 is moved from the retracted position E to the protruding position D by the cam 30. As a result, the driven roller 25b of the second sheet guide member 25 moves to the tangent line A or to the projecting position D that projects from the tangent line A to the first sheet guide member side, and presses the sheet P toward the first sheet guide member side. To do.

For this reason, the drawing direction of the sheet P by the sheet conveying roller pair 21 is the direction of a straight line B3 connecting the contact portion of the feeding roller 16 and the separation pad 17 and the tip of the second sheet guide member 25 as shown in FIG. become. When the drawing direction is the direction of the straight line B3, when the sheet conveying roller pair 21 pulls out the sheet P, a force F3 in the direction of the straight line B3 acts on the separation pad 17 by the sheet P. This force F3 is decomposed into a force Ft3 in the tangential A direction and a force Fn3 in the normal C direction, but this normal direction force Fn3 is away from the feeding roller center 16a.

  For this reason, when the sheet conveying roller pair 21 conveys the sheet P while being held between the separation pad 17 and the feeding roller 16, it can be conveyed while pressing the separation pad 17 against the feeding roller 16 by the pulling force of the sheet P. Disappear. As a result, the support portion does not vibrate integrally with the feeding roller 16, and the generation of noise can be prevented.

  Until the sheet P is conveyed to the sheet conveying roller pair 21, the second sheet guide member 25 is held at the retracted position E by the cam 30, as shown in FIG. There is no collision with the member 25. Further, when the feeding roller 15 feeds the sheet P, the second sheet guide member 25 does not come into contact with the sheet P, so that the second sheet guide member 25 does not become a feeding resistance and is good. Feeding performance can be realized.

  Further, as in the present embodiment, by arranging the driven roller 25b at the rotating end of the second sheet guide member 25, when the sheet conveying roller pair 21 conveys the sheet, the sheet and the second sheet guide member The contact with 25 can be changed from a sliding contact to a rolling contact. As a result, it is possible to reduce the generation of rubbing noise that occurs when the sheet P is fed, and to reduce variations in feeding properties due to feeding resistance.

DESCRIPTION OF SYMBOLS 1 ... Sheet feeding apparatus, 15 ... Feed roller, 16 ... Feed roller, 17 ... Separation pad, 17A ... Separation pad holder, 19 ... Conveyance roller, 19a ... Roller shaft, 21 ... Sheet conveyance roller pair, 22 ... 1st 1 sheet guide member, 23 ... second sheet guide member, 24 ... second sheet guide member, 24a ... boss, 25 ... second sheet guide member, 25b ... driven roller, 28 ... solenoid, 30 ... cam, 40 ... feeding Axis 50 ... Printer 51 ... Printer body 54 ... Sheet separation part D ... Projection position E ... Retraction position P ... Sheet, R ... Sheet conveyance path

Claims (4)

A feed roller that has a notch in the peripheral surface and feeds the sheet by the peripheral surface, a feed roller formed with a smaller diameter than the peripheral surface of the feed roller, and a sheet separation that is in pressure contact with the feed roller A sheet conveying roller pair that conveys a sheet fed by the feeding roller, and is provided in a curved sheet conveying path provided downstream of the feeding roller in the sheet feeding direction. When sheets reaches the sheet conveying roller pair, constituting the feeding roller so that the notch is opposite the sheet separating member, for clamping the sheet between the sheet separating member and the feed roller In the image forming apparatus,
A sheet separating unit configured by the feeding roller and the sheet separating member, for separating the sheet fed by the feeding roller;
A guide member that configures the curved sheet conveying path, is disposed at a position that contacts the leading edge of the sheet that has passed through the sheet separating unit, and guides the contacted sheet toward the pair of sheet conveying rollers ;
A projecting member provided movably to a projecting position adjacent to the guide member between the sheet separating unit and the pair of sheet conveying rollers and a retracted position that does not interfere with sheet feeding by the feeding roller;
A moving part for moving the protruding member to the retracted position and the protruding position,
Before the sheet fed by the feeding roller reaches the sheet conveying roller pair, the projecting member is positioned at the retracted position by the moving unit, and the fed sheet reaches the sheet conveying roller pair. Then, the projecting member is moved from the retracted position to the projecting position by the moving unit, and the sheet conveyed by the sheet conveying roller pair in a state of being sandwiched between the feeding roller and the sheet separating member, is a guide member. An image forming apparatus that is pressed to the side.   2. The protruding position of the protruding member is a position where the pressed sheet is on the extension line of the contact portion of the feeding roller and the separation member or on the sheet separation member side with respect to the extension line. The image forming apparatus described.   The protruding member is pivotally supported on a roller shaft of a conveying roller on a feeding roller side that constitutes the sheet conveying roller pair, and the moving portion is a cam provided on the roller shaft of the feeding roller, and the protruding member The image forming apparatus according to claim 1, wherein the image forming apparatus is moved in accordance with rotation of a roller shaft of the feeding roller.   The image forming apparatus according to claim 1, wherein a rotating body is provided at a portion that presses the sheet when the protruding member moves to the protruding position.

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