JP6632696B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

The present invention is related to sheet feeding apparatus and an image forming apparatus for feeding sheets.

  2. Description of the Related Art A conventional image forming apparatus such as a printer, a copying machine, and a facsimile is provided with a sheet feeding device for feeding a sheet to an image forming unit. This sheet feeding device includes a sheet feeding cassette for storing sheets, a pickup roller for sending out the sheets stored in the sheet feeding cassette, and a sheet feeding device when two or more sheets are sent out by the pickup roller. And a separating unit for separating the sheets one by one.

  The separation unit includes a feed roller that rotates in the same direction as the pickup roller and a separation roller that presses the feed roller with a predetermined pressure (hereinafter referred to as nip pressure). The separation roller is rotatably provided on a roller shaft via a torque limiter that applies a constant rotational load to the separation roller when the separation roller rotates.

  Here, when one sheet is fed to a nip portion between the feed roller and the separation roller (hereinafter, referred to as a separation nip portion), the load torque applied to the torque limiter from the sheet via the separation roller has a predetermined value. Become more. In this case, the separation roller rotates following the sheet conveyed by the feed roller. Further, when two or more sheets enter the separation nip, the load roller does not rotate because the load torque does not exceed the predetermined value. As a result, double feeding of sheets is prevented in the separation nip, Are sent out one by one.

  Incidentally, the pickup roller, feed roller, and separation roller, which are rotating bodies, are formed of a friction member such as rubber, and when the roller is deteriorated due to wear or the like, the roller is removed from the roller shaft and replaced. Here, when replacing the roller, there is a so-called cantilever type in which one end of a roller shaft for supporting the roller is opened so that the roller can be easily replaced.

  However, in the case of cantilever support, for example, in the case of a feed roller and a separation roller, the vertical position and nip pressure of the separation nip portion become unstable depending on the rigidity of the roller shaft. For this reason, there has conventionally been a roller shaft that detachably supports both ends of a roller shaft with a support member (see Patent Document 1).

JP-A-10-181933

  By the way, in such a conventional sheet feeding apparatus, when attaching both ends of the roller shaft to the support member, or when removing the roller shaft from the support member, the roller shaft is removed from the support member while bending while applying a force. There is a need to. Further, when the roller and the torque limiter are fixed to the shaft, not only the roller but also the torque limiter and the roller shaft need to be replaced. Therefore, not only the replacement is troublesome, but also the replacement cost is increased.

  The present invention has been made in view of such a situation, and has as its object to provide a sheet feeding apparatus and an image forming apparatus that can easily replace rollers (rotating bodies).

According to the present invention, in a sheet feeding apparatus, a sheet stacking section on which a plurality of sheets are stacked, a feeding roller for feeding the sheets stacked on the sheet stacking section, and a sheet fed by the feeding roller. A transport roller that transports the sheet, a separation roller that contacts the transport roller to form a separation nip, and separates the sheets one by one in the separation nip; and a separation roller that rotatably supports the separation roller. A shaft, a separation roller holder that supports one end and the other end of the separation roller shaft in the axial direction, a biasing unit that biases the separation roller holder toward the transport roller, and a separation roller that is larger than the separation roller. A sheet limiter provided at a position near the one end of the shaft, and a torque limiter that applies a rotational load to the separation roller, wherein the separation roller shaft is It is possible to rotate in a direction away from the separation roller holder with the one end side as a rotation fulcrum, and to rotate the one end side in a state where the transport roller and the separation roller are not in contact. When the separation roller shaft is rotated in this manner, the separation roller is moved along the axial direction of the separation roller shaft from the other end side of the separation roller shaft without removing the torque limiter from the separation roller shaft. When the separation roller is pressed against the conveyance roller by the urging force of the urging means, the rotation of the separation roller shaft about the one end side as a rotation fulcrum is restricted. that, it is characterized in.

According to the present invention , the separation roller can be easily replaced.

FIG. 1 is a diagram illustrating a schematic configuration of a full-color laser beam printer as an example of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of the sheet feeding device and the sheet feeding device. FIG. 4 is a diagram illustrating a separation roller that forms a separation unit of the sheet feeding device and a separation roller holder that supports the separation roller. FIG. 3 is a first diagram illustrating an exchange operation of the separation roller. FIG. 9 is a second diagram illustrating the replacement operation of the separation roller. FIG. 13 is a third diagram illustrating the replacement operation of the separation roller. The figure explaining the exchange operation | movement of the said separation roller and a torque limiter.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a full-color laser beam printer as an example of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention.

  In FIG. 1, reference numeral 31 denotes a full-color laser beam printer (hereinafter, referred to as a printer), 31A denotes a printer main body which is an image forming apparatus main body, and 31B denotes an image forming unit (image forming means) for forming an image on a sheet. Reference numeral 32 denotes an image reading device installed substantially horizontally above the printer main body 31A, and a paper discharge space P for sheet discharge is formed between the image reading device 32 and the printer main body 31A. Reference numeral 31C denotes a sheet feeding device for feeding the sheets S from the sheet cassette 21 which is a sheet storage unit for storing the sheets S to the image forming unit.

  The image forming unit 31B is of a four-drum full-color type, and includes a laser scanner 28 and four image forming units that form four color toner images of yellow (Y), magenta (M), cyan (C), and black (K). The process cartridge 36 is provided. Here, each process cartridge 36 includes a photosensitive drum 41, a charger 39 as a charging unit, and a developing unit 40 as a developing unit.

  The image forming unit 31B includes an intermediate transfer unit 31D disposed above the process cartridge 36 and a fixing unit 35. Reference numeral 43 denotes a toner cartridge for supplying toner to the developing device 40. The intermediate transfer unit 31D includes a drive roller 29a, a tension roller 29b, and an intermediate transfer belt 29 wound around a driven roller 29c. Further, the intermediate transfer unit 31D includes a primary transfer roller 42 provided inside the intermediate transfer belt 29 and abutting on the intermediate transfer belt 29 at a position facing the photosensitive drum 41. Here, the intermediate transfer belt 29 is configured to rotate in a direction indicated by an arrow by a driving roller 29a driven by a driving unit (not shown).

  Then, a positive transfer bias is applied to the intermediate transfer belt 29 by the primary transfer roller 42, so that the respective color toner images having the negative polarity on the photosensitive drum are sequentially multiplex-transferred to the intermediate transfer belt 29. At a position facing the drive roller 29a of the intermediate transfer unit 31D, a secondary transfer roller 37 constituting a secondary transfer unit that transfers a color image formed on the intermediate transfer belt to the sheet S is provided.

  Further, a fixing unit 35 is disposed above the secondary transfer roller 37, and a first discharge roller pair 34, a second discharge roller pair 34a, and a double-side reversing unit 31E are disposed at the upper left of the fixing unit 35. . 31F is a control unit that controls the image forming operation of the image forming unit 31B and the sheet feeding operation of the sheet feeding device 31C.

  Next, an image forming operation of the printer 31 configured as described above will be described. First, when image information of a document is read by the image reading device 32, the image information is subjected to image processing, converted into an electric signal, and transmitted to the laser scanner 28 of the image forming unit 31B. Then, in the image forming section 31B, the surface of the photosensitive drum 41 of each process cartridge 36 is scanned by the laser light emitted from the laser scanner 28. As a result, the surface of the photosensitive drum 41 whose surface is uniformly charged to a predetermined polarity and potential by the charger 39 is sequentially exposed, and yellow, magenta, and cyan are respectively placed on the photosensitive drum of each process cartridge 36. And black electrostatic latent images are sequentially formed.

  Thereafter, the electrostatic latent image is developed and visualized with yellow, magenta, cyan and black color toners, and the respective color toner images on the photosensitive drums are applied by the primary transfer bias applied to the primary transfer roller. Are sequentially superimposed on the intermediate transfer belt 29 and transferred. Thus, a toner image is formed on the intermediate transfer belt 29.

  Further, the sheet S is sent out from the sheet feeding device 31 </ b> C in parallel with the toner image forming operation, and the fed sheet S is transported by the transport roller pair 26 to the registration roller pair 38. Thereafter, the skew of the sheet S is corrected by the registration roller pair 38, and the sheet S is conveyed to the secondary transfer unit. Then, in the secondary transfer section, the toner image is collectively transferred onto the sheet S by the secondary transfer bias applied to the secondary transfer roller 37.

  Next, the sheet S to which the toner image has been transferred in this manner is conveyed to the fixing unit 35, where the sheet S receives heat and pressure and is fixed on the sheet S as a color image. Thereafter, for example, when an image is formed on one side, the sheet S on which the image has been fixed is discharged from the sheet discharge space P by a first discharge roller pair 34 or a second discharge roller pair 34a provided downstream of the fixing unit 35. And is stacked on the stacking portion 45 protruding from the bottom surface of the paper discharge space P.

  FIG. 2 is a diagram illustrating a configuration of a sheet feeding device 31C according to the present embodiment. 2A is a perspective view of the sheet feeding device 31C, and FIG. 2B is a side view of the sheet feeding device 31C. In FIG. 2, reference numeral 1 denotes a pickup roller serving as a sheet feeding means for feeding the sheets S stacked on the sheet feeding cassette 21, and reference numeral 2 denotes a feed roller serving as a sheet conveying means for conveying the sheet S sent out by the pickup roller 1. It is. Reference numeral 3 denotes a separation roller which is a rotating body which comes into contact with and separates from the feed roller 2, and the separation roller 3 forms a plurality of sheets together with a feed roller (conveyance roller) 2 which is another rotating body located above. The separation unit 2a is configured to separate each of them.

  Reference numeral 7 denotes a feed roller shaft which is rotated by a drive unit (not shown), and reference numeral 8 denotes a pickup roller shaft of the pickup roller 1 provided in parallel with the feed roller shaft 7. Then, the rotation of the feed roller shaft 7 is transmitted to the pickup roller shaft 8 via the gear train 9, and the pickup roller 1 and the feed roller 2 rotate in the sheet feeding direction. Reference numeral 5 denotes a separation roller shaft, and a torque limiter 4 for applying a constant rotational load when the separation roller 3 rotates in the sheet feeding direction is attached to the separation roller shaft 5. The separation roller 3 is detachably attached to a separation roller shaft 5 serving as a shaft, and is rotatably mounted via a torque limiter 4.

  The separation roller 3 is rotated by the rotation of the feed roller 2 when only one sheet or no sheet enters the separation nip between the feed roller 2 and the separation roller 3 by the action of the torque limiter 4. I do. When two or more sheets enter the separation nip, the load torque applied to the torque limiter 4 from the sheets via the separation roller 3 does not exceed a predetermined value, so that the separation roller 3 is stopped. Prevent double feeding of sheets.

  In FIG. 2, reference numeral 18 denotes a support base which is rotatably (movably) supported by a printer main body 31A also serving as a sheet feeding apparatus main body, with a rotation shaft 19 serving as a fulcrum in a vertical direction. Reference numeral 6 denotes a separation roller holder that supports the separation roller shaft 5 and rotatably supports the separation roller 3 via the separation roller shaft 5. The separation roller holder 6 is urged by a spring 17 so that the separation roller 3 comes into pressure contact with the feed roller 2 so as to be able to come and go.

  Here, the separation roller holder 6 as the shaft support means supports both ends of the separation roller shaft 5 as shown in FIG. The separation roller holder 6 has a U-shaped groove 10 which is a locking concave part whose upper part is open and which locks one end 5a of the separation roller shaft 5 in a detachable manner. Further, the separation roller holder 6 rotatably supports the other end of the separation roller shaft 5 so that the separation roller shaft 5 is rotatable in a vertical direction in which the locking by the U-shaped groove 10 is released. It has a bearing 10a as a support.

  As a result, the separation roller 3 is locked (fitted) into the U-shaped groove 10 whose one end 5a is open at the top, and rotates vertically about the rotation shaft 11 supported by the bearing 10a. It becomes possible. When the separation roller shaft 5 is fitted in the U-shaped groove 10, the separation roller 3 is restricted from moving in the axial direction by the retaining wall 20 having the U-shaped groove 10. There is no deviation from the shaft 5. In addition, in the present embodiment, since the separation roller 3 that can rotate in the vertical direction is normally pressed against the feed roller 2 by the spring 17, the rotation of the separation roller shaft 5 is regulated by the feed roller 2. .

  Next, replacement and removal of the separation roller 3 configured as described above will be described. Here, in this embodiment, since the separation roller 3 is in pressure contact with the feed roller 2 as shown in FIG. 2 described above, when the separation roller shaft 5 is rotated, the separation roller 3 It interferes with the roller 2.

  For this reason, when exchanging and removing the separation roller 3, the fixing means (not shown) is first removed. Thereafter, as shown in FIG. 4A, when the support table 18 serving as the rotating body support means is rotated about the rotation shaft 19 as a fulcrum, the separation roller 3 is connected to the feed roller 2 when the separation roller shaft 5 is rotated. Rotate (move) to a position that does not interfere. Next, one end of the separation roller shaft 5 is disengaged from the U-shaped groove 10 of the separation roller holder 6, and thereafter, the rotation shaft 11 is centered in FIGS. 4B and 5A. As shown in (2), the separation roller shaft 5 is rotated upward.

  For example, the separation roller 3 and the torque limiter 4 relate to a concave shape (not shown) formed on the separation roller 3 and a convex shape 12 formed on the side surface of the torque limiter 4 on the separation roller side shown in FIG. By the combination, the rotation of the separation roller 3 is transmitted to the torque limiter 4. In the present embodiment, the torque limiter 4 is locked on the separation roller shaft 5 and does not move on the separation roller shaft.

  That is, although the torque limiter 4 applies a constant rotational load when the separation roller 3 rotates in the sheet feeding direction, the torque limiter 4 and the separation roller 3 are not connected in the axial direction. As a result, as shown in FIG. 4B, if the separation roller 3 is pulled upward along the separation roller shaft 5 from the separation roller shaft 5 that has been rotated upward, only the separation roller 3 is removed. be able to.

  When the separation roller 3 is replaced and mounted, a new separation roller 3 is mounted on the separation roller shaft 5 and engaged with the torque limiter 4 in the reverse procedure of removal. Thereafter, the separation roller shaft 5 is rotated downward about the rotation shaft 11 to a position where one end 5a is fitted into the U-shaped groove 10 of the separation roller holder 6, thereby fixing the separation roller 3. Complete.

  As described above, the separation roller shaft 5 having both ends supported is rotatably supported with one end serving as a fulcrum, so that when the separation roller 3 is replaced, the separation roller shaft 5 is not forcibly bent. It can be attached and detached, and only the separation roller 3 can be replaced. That is, when the separation roller 3 is replaced as in the present embodiment, the separation roller shaft 5 is rotated upward while the support of one end of the separation roller shaft 5 is released to open one end of the separation roller shaft 5. Thus, the separation roller 3 can be easily replaced. Further, since the separation roller 3 can be replaced without replacing the separation roller holder 6 together, only the separation roller 3 can be replaced, so that the replacement labor and replacement cost can be reduced.

  In the above description, a case has been described in which, when the separation roller 3 is replaced, the support base 18 is rotated to a position where the separation roller 3 does not interfere with the feed roller 2, and then the separation roller shaft 5 is rotated upward. However, the present invention is not limited to this. For example, when the separation roller holder 6 is detachably provided on the support base 18 and the separation roller 3 is replaced, the separation roller holder 6 is detached from the support base 18 and then separated as shown in FIG. The roller 3 may be removed. In the case of such a configuration, the replacement operation of the separation roller 3 can be performed in a wide place, so that the replacement operation is facilitated.

  Although the case where the separation roller 3 is replaceably provided on the separation roller shaft 5 has been described so far, the present invention is not limited to this, and the separation roller 3 is connected to the separation roller shaft 5 as shown in FIGS. In addition, the torque limiter 4 may be provided so as to be replaceable. In this case, if the shaft side protrusion 15 provided on the separation roller shaft 5 is engaged with the engagement recess 13 provided on the torque limiter 4, the separation between the torque limiter 4 and the torque limiter 4 on the separation roller shaft 5 is achieved. The roller shaft 5 can be uncoupled in the axial direction.

  As a result, the separation roller 3 and the torque limiter 4 can be removed by rotating the separation roller shaft 5 upward about the rotation shaft 11 and opening one end of the separation roller shaft 5. As a result, the separation roller 3 and the torque limiter 4 having different replacement times can be individually replaced without replacing the separation roller holder 6 together.

  Further, the separation roller 3 has been described as an example of the rotating body, but the present invention is not limited to this, and can be applied to another roller configured to be detachably attached to a shaft. Although the case where the rotating body is detachably attached to the non-rotating shaft has been described so far, the present invention is not limited to this, and even if the rotating body has a fixed rotatable shaft, the rotating body can be rotated. By moving the shaft to open one end of the shaft, the effects described above can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Pickup roller, 2 ... Feed roller, 2a ... Separation part, 3 ... Separation roller, 4 ... Torque limiter, 5 ... Separation roller shaft, 6 ... Separation roller holder, 10 ... U-shaped groove, 10a ... Bearing part, 11 ... Rotating shaft, 18: support base, 19: rotating shaft, 31: full-color laser beam printer, 31A: printer body, 31B: image forming unit, 31C: sheet feeding device, S: sheet

Claims (15)

  A sheet stacking unit on which a plurality of sheets are stacked,
A feed roller for feeding the sheets stacked on the sheet stacking unit,
  A transport roller that transports the sheet fed by the feed roller,
  A separation roller for forming a separation nip by contacting the transport roller, and separating the sheets one by one in the separation nip;
  A separation roller shaft rotatably supporting the separation roller,
  A separation roller holder that supports one end and the other end in the axial direction of the separation roller shaft,
  Urging means for urging the separation roller holder toward the transport roller;
  A torque limiter, which is provided at a position closer to the one end side of the separation roller shaft than the separation roller, applies a rotational load to the separation roller,
  A sheet feeding device comprising:
  The separation roller shaft can rotate in a direction away from the separation roller holder with the one end side as a rotation fulcrum,
  When the separation roller shaft is rotated with the one end side as a rotation fulcrum in a state where the transport roller and the separation roller are not in contact with each other, the separation is performed without removing the torque limiter from the separation roller shaft. It is possible to remove the roller from the other end side of the separation roller shaft along the axial direction of the separation roller shaft,
  In a state where the separation roller is in pressure contact with the transport roller by the urging force of the urging means, rotation of the separation roller shaft around the one end side as a rotation fulcrum is restricted.
  A sheet feeding device, characterized in that:   The separation roller holder is engageable with the other end of the separation roller shaft, and faces the conveyance roller such that the other end of the separation roller shaft can move in a direction approaching the conveyance roller. Having a groove open on the side,
  The sheet feeding device according to claim 1, wherein:   The separation roller is disposed below the transport roller,
  The groove is formed in a U-shape with an open top.
  The sheet feeding device according to claim 2, wherein:   The separation roller shaft is rotatable around a rotation shaft provided on the one end side of the separation roller shaft,
  The sheet feeding device according to any one of claims 1 to 3, wherein:   The rotation axis is orthogonal to the separation roller axis and extends in a direction along a sheet conveying direction in the separation nip.
  The sheet feeding device according to claim 4, wherein:   The separation roller holder has a bearing that rotatably supports the rotation shaft,
  The sheet feeding device according to claim 4 or 5, wherein   Comprising a transport roller shaft that supports the transport roller,
  The sheet feeding device according to any one of claims 1 to 6, wherein:   A support table that rotatably supports the separation roller holder,
  The sheet feeding device according to any one of claims 1 to 7, wherein:   The torque limiter is removable from the other end side of the separation roller shaft,
  The sheet feeding device according to any one of claims 1 to 8, wherein:   The separation roller and the torque limiter are engaged, and rotation of the separation roller is transmitted to the torque limiter.
  The sheet feeding device according to any one of claims 1 to 9, wherein:   The transport roller is a drive roller rotated by a drive unit,
  The separation roller is a driven roller that is driven and rotated by the transport roller,
  The sheet feeding device according to any one of claims 1 to 10, wherein:   When the other end side of the separation roller shaft is supported by the separation roller holder, the separation roller is restricted from moving in the axial direction on the separation roller shaft by a wall provided in the separation roller holder,
  The sheet feeding device according to any one of claims 1 to 11, wherein:   The biasing means is a spring;
  The sheet feeding device according to claim 1, wherein   In a state where the separation roller is pressed against the conveyance roller by the urging force of the urging unit, the rotation of the separation roller shaft around the one end side as a rotation fulcrum is opposed to the separation roller. Regulated by transport rollers,
  The sheet feeding device according to claim 1, wherein   Image forming means for forming an image on a sheet;
  The sheet feeding device according to any one of claims 1 to 14, which conveys a sheet to the image forming unit.
  An image forming apparatus comprising:

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