JP2018016458A - Sheet conveyance device and image formation apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveyance device which improves the workability relevant to replacement of a retarded roller and the like.SOLUTION: A sheet conveyance device 5 includes: a conveyance roller which conveys a sheet; a retarded roller 40 which is brought into pressure-contact with the conveyance roller; a first holder 41 which rotatably supports the retarded roller 40; a nip formation spring which biases the retarded roller 40 to the conveyance roller via the first holder 41; a second holder 42 which rotatably supports the first holder 41; a storage part 60 which detachably stores the second holder 42; and a hook part 34 which is elastically deformed between an engagement position P1 set to the position engaged with the second holder 42 stored in the storage part 60 and a release position set to the position releasing engagement with the second holder 42. The first holder 41 includes a contact part 48 which presses the hook part 34 from the engagement position P1 to the release position when being pushed against the biasing force of the nip formation spring.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus including the sheet conveying apparatus.

  The image forming apparatus includes a sheet conveying device for conveying a sheet.

  For example, the sheet conveying apparatus described in Patent Literature 1 includes a paper feeding unit in which a feeding roller is rotatably supported by a holder, and a retard roller pressed against the feeding roller. The paper feed unit is provided in the apparatus main body, and the retard roller is provided in the paper feed cassette. The retard roller is provided to prevent conveyance (multifeed) of a plurality of overlapping sheets.

JP 2008-81308 A

  Since the retard roller of the sheet conveying apparatus as described above is a consumable item, it is mounted on the paper feed cassette so that it can be replaced. However, since the retard roller and its peripheral parts are reduced in size with the need for downsizing of the image forming apparatus, there is a problem that it is difficult to replace the retard roller.

  In order to solve the above-described problems, the present invention provides a sheet conveying apparatus that improves workability related to replacement of a retard roller and the like, and an image forming apparatus including the sheet conveying apparatus.

  In order to achieve the above-described object, the sheet conveying apparatus of the present invention is arranged above the apparatus main body, a conveyance guide section provided in the apparatus main body on the downstream side of the sheet storage section that accommodates sheets, and above the conveyance guide section. A transport roller that transports the sheet, a retard roller that is pressed against the transport roller, a first holder that rotatably supports the retard roller, and the transport roller that supports the retard roller via the first holder. An urging member that urges the first holder, a second holder that rotatably supports the first holder, an accommodation portion that is provided in the conveyance guide portion and detachably accommodates the second holder; An engagement position provided in the housing portion and set at a position for engaging with the second holder housed in the housing portion and a position for releasing the engagement with the second holder. A hook portion that is elastically deformable with respect to the released position, and the first holder engages the hook portion when pushed against the urging force of the urging member. A contact portion that presses from the combined position toward the release position is included.

  In this case, a separation assisting member that urges the second holder in a direction to disengage the second holder from the accommodating portion is further included, and the second holder is configured to disengage the separation assisting member when the hook portion is displaced to the release position. It is preferable that the urging force is removed from the accommodating portion.

In this case, the second holder has a guide surface portion on the downstream side of the retard roller,
It is preferable that the guide surface portion has a notch portion that is notched downstream from an edge portion that faces the retard roller.

  In this case, any one of the hook part and the contact part is inclined toward the release position side from the downstream side in the pushing direction of the first holder toward the upstream side, and any one of the hook part and the contact part It is preferable to include an inclined surface in sliding contact with the other.

  In order to achieve the above object, an image forming apparatus according to the present invention includes any one of the sheet conveying apparatuses described above.

  ADVANTAGE OF THE INVENTION According to this invention, the workability | operativity which concerns on replacement | exchange of a retard roller etc. can be improved.

1 is a cross-sectional view schematically showing an internal structure of a color printer according to a first embodiment of the present invention. 1 is a perspective view illustrating a part of a sheet feeding cassette and a sheet conveying apparatus according to a first embodiment of the present invention. It is sectional drawing which shows a part of sheet conveying apparatus which concerns on 1st Embodiment of this invention. FIG. 3 is a perspective view showing a part of the sheet conveying apparatus according to the first embodiment of the present invention. FIG. 3 is an exploded perspective view illustrating a double feed preventing unit of the sheet conveying apparatus according to the first embodiment of the present invention. It is VI-VI sectional drawing of FIG. It is VII-VII sectional drawing of FIG. It is sectional drawing which shows the removal process of the double feed prevention part of the sheet conveying apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the mounting process of the double feed prevention part of the sheet conveying apparatus which concerns on 1st Embodiment of this invention. It is a perspective view which shows a part of sheet conveying apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the removal process of the double feed prevention part of the sheet conveying apparatus which concerns on 2nd Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following, description will be made with reference to the directions shown in the drawings. The terms “upstream” and “downstream” and similar terms refer to “upstream” and “downstream” in the feeding direction of the sheet S and similar concepts.

  With reference to FIG. 1, an overall configuration of a printer 1 as an example of an image forming apparatus will be described. FIG. 1 is a cross-sectional view schematically showing the internal structure of the printer 1.

  The printer 1 includes an apparatus main body 2, a paper feed cassette 3, and a paper discharge tray 4. The paper feed cassette 3 is detachably provided at the lower part of the apparatus body 2 having a substantially rectangular box shape. A sheet S (bundle) is accommodated inside the paper feed cassette 3. The paper discharge tray 4 is provided in the upper part of the apparatus main body 2. The sheet S is not limited to paper and may be a resin film or the like.

  The printer 1 includes a sheet conveying device 5, an image forming unit 6, and a fixing device 7 inside the apparatus main body 2. The sheet conveyance device 5 is provided on the upstream side of a conveyance path 8 extending from the paper feed cassette 3 to the paper discharge tray 4. The image forming unit 6 is provided in an intermediate portion of the conveyance path 8. The fixing device 7 is provided on the downstream side of the conveyance path 8.

  The image forming unit 6 includes a toner container 10, a drum unit 11, and an optical scanning device 12. The toner container 10 contains, for example, black toner (developer). The drum unit 11 includes a photosensitive drum 13, a charging device 14, a developing device 15, a transfer roller 16, and a cleaning device 17. The photosensitive drum 13 carries a toner image developed by the developing device 15. The transfer roller 16 is in contact with the photosensitive drum 13 to form a transfer nip.

  The sheet transport device 5 sends out the sheet S in the paper feed cassette 3 toward the transport path 8. The toner image on the photosensitive drum 13 is transferred to the sheet S that passes through the transfer nip. The fixing device 13 fixes the toner image on the sheet S. The sheet S after the fixing process is discharged to the paper discharge tray 4.

  Next, the sheet feeding cassette 3 and the sheet conveying device 5 will be described with reference to FIGS. FIG. 2 is a perspective view showing a part of the sheet feeding cassette 3 and the sheet conveying device 5. FIG. 3 is a cross-sectional view showing a part of the sheet conveying apparatus 5. FIG. 4 is a perspective view showing a part of the sheet conveying apparatus 5. FIG. 5 is an exploded perspective view showing the double feed preventing unit 32 of the sheet conveying apparatus 5. 6 is a cross-sectional view taken along the line VI-VI in FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG.

  As shown in FIGS. 1 and 2, the sheet feeding cassette 3 as an example of a sheet storage portion includes a cassette body 20 and a design surface portion 21. The cassette body 20 is formed in a substantially rectangular box shape for accommodating the sheet S. The design surface portion 21 is provided at an end portion of the cassette body 20. The design surface portion 21 constitutes a part of the exterior surface of the apparatus main body 2 in a state where the paper feed cassette 3 is mounted on the apparatus main body 2. The following description is based on the state where the paper feed cassette 3 is mounted on the apparatus main body 2.

  The cassette body 20 includes a lift plate 22, a pair of first cursors 23, and a second cursor (not shown).

  The lift plate 22 is disposed on the bottom plate of the cassette body 20. The lift plate 22 is provided so as to be rotatable in the vertical direction around a pair of front and rear plate rotation shafts 24. The lift plate 22 is biased by the push-up spring 25 and rotates upward (see FIG. 1). The lift plate 22 is pressed by a pressure device (not shown) and rotates downward against the urging force of the push-up spring 25.

  As shown in FIG. 2, the pair of first cursors 23 are opposed to each other with the lift plate 22 in between, and are connected to an interlocking mechanism (not shown) such as a rack and pinion. The pair of first cursors 23 slides back and forth symmetrically along the width direction, and aligns the front and rear widths of the sheets S (bundles) placed on the lift plate 22. The second cursor is provided so as to be slidable in the left-right direction (feeding direction), and aligns the rear end face of the sheet S (bundle).

  The sheet conveying device 5 is provided on the right side (downstream in the feeding direction) of the sheet feeding cassette 3 (see FIG. 1). As shown in FIG. 3, the sheet conveying device 5 includes a paper feeding unit 31, a multifeed preventing unit 32, a conveyance guiding unit 33, a hook unit 34 (see FIG. 7), and a separation assisting spring 35 (see FIG. 7). ) And.

  The paper feed unit 31 includes a paper feed holder 31a that rotatably supports the pickup roller 31b and the transport roller 31c. The paper feed holder 31a is formed in a substantially rectangular parallelepiped shape with the lower surface opened. The pickup roller 31b and the transport roller 31c are each formed in a columnar shape extending in the front-rear direction.

  An upper guide 30 is provided above the transport guide 33. The upper guide portion 30 is formed with an upper recess (not shown) that detachably holds the paper feed holder 31a. The pickup roller 31b is disposed on the left side (upstream side) of the paper feed holder 31a, and the transport roller 31c is disposed on the right side (downstream side) of the paper feed holder 31a. The pickup roller 31b is disposed on the upper right side of the lift plate 22 (see FIG. 1). The conveyance roller 31c is connected to a drive motor (not shown), and the pickup roller 31b is connected to the conveyance roller 31c via an idle gear (not shown).

  The transport roller 31c is driven by a drive motor (not shown) and rotates around the axis. The pickup roller 31b also rotates in the same direction as the transport roller 31c via the idle gear. The pickup roller 31 b sends out the sheet S in the paper feed cassette 3 toward the conveyance path 8. The conveyance roller 31c conveys the sheet S sent to the conveyance path 8 toward the downstream.

  As shown in FIG. 3, the double feed preventing unit 32 is arranged to face the lower side of the paper feeding unit 31 (conveying roller 31 c). As shown in FIGS. 4 and 5, the double feed preventing unit 32 includes a retard roller 40, a first holder 41, a second holder 42, and a nip forming spring 43 (see FIG. 6). The following description is based on the assembled state of the double feed prevention unit 32.

  The retard roller 40 is formed in a cylindrical shape extending in the front-rear direction. The retard roller 40 is provided at a position where it is in pressure contact with the transport roller 31c (see FIG. 3). The retard roller 40 includes a torque limiter 40a for interrupting torque transmission. The torque limiter 40 a is formed integrally with the retard roller 40. The retard roller 40 and the torque limiter 40a are rotatably supported by the fixed shaft 40b (see FIG. 5). The front and rear end portions of the fixed shaft 40b each have a substantially D-shaped cross section.

  As shown in FIGS. 5 and 6, the first holder 41 includes a connecting portion 45 and a pair of arm portions 46. The first holder 41 is integrally formed in a substantially U shape so as to accommodate the retard roller 40 (torque limiter 40a).

  The connecting portion 45 is disposed so as to cover the lower portion of the retard roller 40. The connecting portion 45 is formed in a substantially plate shape that is curved along the outer peripheral surface of the retard roller 40. On the lower surface of the connecting portion 45, a first pedestal 47 is formed so as to form a slope inclined in the lower left direction. The first pedestal 47 is formed in the middle of the connecting portion 45 in the front-rear direction. A first protrusion 47 a is provided on the first pedestal 47. The first protrusion 47 a extends from the first base 47 in the lower right direction. In addition, a contact portion 48 is provided on the rear side of the connecting portion 45 (see FIG. 7). The contact portion 48 extends from the lower surface of the connecting portion 45 in the lower right direction.

  The pair of arm portions 46 extends rightward from both front and rear end portions of the connecting portion 45. A fixing hole 46 a into which the fixing shaft 40 b of the retard roller 40 is fitted is formed on the left side (the connecting portion 45 side) of each arm portion 46. The fixed shaft 40b is non-rotatably supported by the first holder 41 by being fitted into the fixed hole 46a. That is, the first holder 41 rotatably supports the retard roller 40 via the fixed shaft 40b. A rotation engagement portion 46 b is formed at the tip end portion (right end portion) of each arm portion 46. Each rotation engaging part 46b is recessedly provided in the substantially U shape which open | releases a front end surface seeing from the front.

  As shown in FIGS. 4 to 6, the second holder 42 includes a bottom surface portion 50, a side surface portion 51, a guide surface portion 52, and a pair of front and rear end surface portions 53. These surface portions 50 to 53 are integrally formed in a substantially box shape so as to enclose the first holder 41.

  As shown in FIG. 6, the bottom surface portion 50 is disposed below the connecting portion 45 of the first holder 41. The bottom surface portion 50 constitutes the lower left side of the second holder 42. That is, the lower right side of the second holder 42 is open. A chamfered portion 50 a is formed at the lower right corner of the bottom surface portion 50. A second pedestal 54 projects downward from the bottom surface portion 50. The second pedestal 54 is disposed opposite the first pedestal 47 of the first holder 41 at the middle part in the front-rear direction of the bottom surface part 50. The second pedestal 54 is provided with a second protrusion 54a protruding in the upper left direction.

  The side surface portion 51 extends upward from the left end portion of the bottom surface portion 50. As shown in FIGS. 4 to 6, an entrance guide 51 a that is upwardly inclined in the right direction is formed on the upper portion of the side surface portion 51. The guide surface portion 52 is provided at a position separated from the side surface portion 51 in the right direction. The guide surface portion 52 is formed to have an upward slope from the left side to the right side. The guide surface portion 52 is curved so as to protrude downward when viewed from the front. The upper surface of the guide surface portion 52 constitutes a part of the upstream side of the transport path 8.

  The pair of front and rear end surface portions 53 are formed so as to connect the front and rear end portions of the bottom surface portion 50, the side surface portion 51, and the guide surface portion 52. The upper surface of each end surface portion 53 is formed to be curved along the guide surface portion 52. An accommodation space SP1 for accommodating the first holder 41 is formed in a range surrounded by the side surface portion 51, the guide surface portion 52, and the pair of end surface portions 53.

  A pair of front and rear positioning bosses 53a project from the outer surface of the pair of front and rear end surface portions 53. Each positioning boss 53a is formed in a cylindrical shape, and is disposed in the middle in the left-right direction above the end surface portion 53. Between the pair of front and rear end surface portions 53 and the guide surface portion 52, a pair of front and rear slits 55 for allowing the arm portion 46 of the first holder 41 to enter is formed. The pair of front and rear slits 55 are provided with a pair of front and rear engagement shafts 56 for engaging the rotation engagement portion 46b of the arm portion 46 (see FIG. 5). By engaging the engagement shaft 56 with the rotation engagement portion 46 b, the first holder 41 is supported by the second holder 42 so as to be rotatable (swingable) about each engagement shaft 56. .

  As shown in FIG. 6, the nip forming spring 43 as an example of the urging member is a compression coil spring, for example, and is installed between the first holder 41 and the second holder 42. Both end portions of the nip forming spring 43 are fitted to the first protrusion 47 a of the first base 47 and the second protrusion 54 a of the second base 54. The nip forming spring 43 urges the retard roller 40 toward the transport roller 31 c via the first holder 41. That is, the first holder 41 rotates upward about the engagement shaft 56 and presses the retard roller 40 against the transport roller 31c. Thereby, the conveyance nip N (refer FIG. 3) can be formed between the conveyance roller 31c and the retard roller 40. FIG.

  Next, as illustrated in FIG. 2, the conveyance guide unit 33 is made of, for example, a synthetic resin and is formed in a substantially trapezoidal column shape that is long in the front-rear direction. The conveyance guide portion 33 is formed to have substantially the same front-rear width as the paper feed cassette 3. A curved conveyance guide surface is formed on the upper surface of the conveyance guide portion 33 so as to have an upward gradient from the left side toward the right side. The conveyance guide unit 33 constitutes a part of the upstream side of the conveyance path 8 and guides the sheet S to be conveyed.

  As shown in FIG. 4, an accommodating portion 60 is recessed in the center portion in the width direction (front-rear direction) of the conveyance guide portion 33. The accommodating portion 60 is formed in a range surrounded by a pair of front and rear inner walls 61 and a bottom wall 62. The accommodating part 60 is a substantially rectangular parallelepiped space with the left and upper surfaces open. The accommodating part 60 is provided in order to accommodate the 2nd holder 42 so that attachment or detachment is possible.

  The pair of front and rear inner walls 61 are provided with a pair of front and rear positioning recesses 61 a into which the positioning bosses 53 a of the second holder 42 are fitted. The pair of front and rear positioning recesses 61 a are guide grooves formed so as to be recessed downward from the upper end surface of the inner wall 61. With the positioning boss 53a fitted in the positioning recess 61a, the second holder 42 is positioned in the front-rear direction and the left-right direction. In this state, the upper surface (the guide surface portion 52 and the like) of the second holder 42 is disposed at substantially the same height as the upper surface of the transport guide portion 33 (see FIG. 2). That is, the conveyance guide surface of the sheet S is formed.

  As shown in FIG. 7, the hook portion 34 is made of, for example, a synthetic resin and is erected on the rear side of the bottom wall 62. The hook part 34 includes a claw part 64 connected to the upper end part of the substantially plate-like elastic part 63. The elastic portion 63 extends upward from the bottom wall 62. The elastic portion 63 is formed so as to be elastically deformable in the left-right direction with the base end portion as the center. That is, the free end (upper end) of the elastic portion 63 swings in the left-right direction. The nail | claw part 64 is formed in the substantially triangular shape which protrudes on the left side seeing from the front. The claw portion 64 includes an engagement surface 64a and an inclined surface 64b. The engaging surface 64a extends substantially horizontally in the left direction. The inclined surface 64b extends obliquely upward to the right from the tip of the engaging surface 64a.

  Note that the hook portion 34 is arranged so as not to hinder the mounting of the double feed preventing portion 32 to the accommodating portion 60. Specifically, the elastic portion 63 is disposed at a position that does not interfere with the bottom surface portion 50 of the second holder 42. On the other hand, the nail | claw part 64 is arrange | positioned in the position which can contact the bottom face part 50. FIG.

  The separation assisting spring 35 as an example of the separation assisting member is, for example, a compression coil spring. A lower end portion of the separation assisting spring 35 is supported by a third pedestal 65 located on the rear side of the bottom wall 62. The separation assisting spring 35 is fixed on the third pedestal 65 in a standing posture. The third pedestal 65 is disposed below the bottom surface portion 50 of the second holder 42 in a state where the double feed preventing portion 32 is accommodated in the accommodating portion 60. In this state, the separation assisting spring 35 is provided between the third pedestal 65 and the bottom surface portion 50. The separation assisting spring 35 biases the second holder 42 upward. That is, the detachment assisting spring 35 biases the second holder 42 in a direction in which the second holder 42 is detached from the housing portion 60.

  As shown in FIG. 7, the hook portion 34 is engaged with the second holder 42 in a state where the double feed prevention portion 32 is accommodated in the accommodation portion 60. Specifically, the engagement surface 64 a of the claw portion 64 engages with the upper surface of the bottom surface portion 50 of the second holder 42. At this time, the bottom surface portion 50 of the second holder 42 is urged by the separation assisting spring 35 and is brought into pressure contact with the engagement surface 64 a of the claw portion 64. That is, the bottom surface portion 50 is sandwiched and fixed between the separation assisting spring 35 and the claw portion 64. On the other hand, as will be described in detail later, when the hook portion 34 is elastically deformed and the engaging surface 64a of the claw portion 64 is separated from the second holder 42, the double feed preventing portion 32 can be taken out from the accommodating portion 60 (FIG. 8). As described above, the hook part 34 is set to a position for releasing the engagement between the engagement position P <b> 1 set to the position for engaging the second holder 42 accommodated in the accommodation part 60 and the second holder 42. It is provided so as to be elastically deformable with respect to the release position P2 (see FIG. 8).

  Next, the operation of the sheet conveying device 5 will be described. As shown in FIG. 1, the lift plate 22 is urged by the push-up spring 25 to push up the bundle of sheets S. The pickup roller 31 b contacts the uppermost sheet S in the bundle of sheets S and sends the sheet S toward the conveyance nip N.

  When one sheet S is fed into the conveyance nip N, the retard roller 40 receives a large torque (torque exceeding the setting of the torque limiter 40a) from the conveyance roller 31c with the sheet S interposed therebetween, and is driven to rotate. And this sheet | seat S is conveyed toward a downstream. On the other hand, when two sheets S are sent to the conveyance nip N, the torque transmitted from the conveyance roller 31c to the retard roller 40 becomes weak. For this reason, the torque limiter 40a operates and the retard roller 40 stops. Therefore, the sheet S that contacts the transport roller 31c is transported toward the downstream side, and the sheet S that contacts the retard roller 40 stops.

  The retard roller 40 wears over time in order to prevent double feeding of the sheet S using friction. The worn retard roller 40 is replaced with a new retard roller 40.

  Next, with reference to FIGS. 8 and 9, the replacement work of the double feed prevention unit 32 will be described. FIG. 8 is a cross-sectional view showing a process of removing the double feed preventing portion 32. FIG. 9 is a cross-sectional view showing the mounting process of the double feed preventing portion 32. In the following description, it is assumed that the cover of the apparatus main body 2 and the conveyance unit (not shown) are opened and the operator can work on the sheet conveyance apparatus 5. In the following description, it is assumed that the paper feed unit 31 (paper feed holder 31a) is detached from the upper guide unit 30.

  First, as shown in FIG. 8, the operator performs an operation of taking out the double feed prevention unit 32 including the worn retard roller 40. Specifically, the operator pushes the retard roller 40 downward against the urging force of the nip forming spring 43. The first holder 41 rotates to the lower right about each engagement shaft 56, and the contact portion 48 of the first holder 41 contacts the claw portion 64 of the hook portion 34.

  Here, the inclined surface 64b of the claw portion 64 is inclined toward the release position P2 from the downstream side in the pushing direction of the first holder 41 toward the upstream side. Therefore, when the first holder 41 is pushed in, the contact portion 48 slides downward on the inclined surface 64b, and the hook portion 34 is directed from the engagement position P1 (see FIG. 7) to the release position P2 (right direction). And press. When the contact portion 48 slides on the inclined surface 64b of the hook portion 34, the force for rotating the first holder 41 is converted into the force for elastically deforming the hook portion 34. Thereby, the hook part 34 can be easily and smoothly moved from the engagement position P1 to the release position P2.

  When the hook portion 34 is elastically deformed to the release position P2, the second holder 42 (multifeed prevention portion 32) is urged by the separation assisting spring 35 and slightly pushed up. Subsequently, when the operator gradually weakens the force for pushing the retard roller 40, the double feed preventing portion 32 is automatically detached from the accommodating portion 60 by the urging force of the separation assisting spring 35. The hook portion 34 returns from the release position P2 to the engagement position P1 by its own elastic force.

  Next, as shown in FIG. 9, the worker performs an installation operation of the double feed prevention unit 32 including the new retard roller 40. Specifically, the operator aligns each positioning boss 53a with each positioning recess 61a (see FIG. 4), and pushes the new double feed prevention unit 32 into the housing unit 60 from above. Then, the bottom surface portion 50 (the chamfered portion 50 a) of the second holder 42 comes into contact with the claw portion 64 of the hook portion 34.

  When the double feed preventing portion 32 is further pushed in, the chamfered portion 50a of the bottom surface portion 50 slides downward on the inclined surface 64b of the claw portion 64 and presses the hook portion 34 from the engagement position P1 toward the release position P2. To do. The operator pushes the double feed preventing portion 32 to a predetermined position where the engaging surface 64a of the claw portion 64 can be engaged with the upper surface of the bottom surface portion 50. When the double feed preventing portion 32 is pushed to a predetermined position, the hook portion 34 returns from the release position P2 to the engagement position P1 by its own elastic force (see FIG. 7). As described above, the engagement surface 64a of the hook portion 34 is engaged with the upper surface of the bottom surface portion 50, and the mounting (replacement operation) of the double feed prevention portion 32 to the accommodating portion 60 is completed.

  According to the sheet conveying device 5 described above, the engagement between the hook portion 34 and the second holder 42 is released in conjunction with the pressing of the retard roller 40 (first holder 41). That is, the multifeed prevention unit 32 can be detached from the storage unit 60 simply by pushing the retard roller 40. Thereby, the multifeed prevention part 32 can be taken out from the accommodating part 60 smoothly. That is, the workability related to the replacement of the double feed prevention unit 32 can be improved.

  Further, when the engagement between the hook portion 34 and the second holder 42 is released, the double feed preventing portion 32 is urged by the separation assisting spring 35 and is separated from the accommodating portion 60. That is, the multifeed prevention unit 32 (second holder) is automatically detached from the storage unit 60 simply by pushing the retard roller 40 (first holder 41). Thereby, even if it is the downsized sheet conveying apparatus 5 (printer 1), the multifeed prevention part 32 can be taken out from the accommodating part 60 easily and rapidly. Therefore, usability related to maintenance can be improved.

  Next, a sheet conveying apparatus 70 according to the second embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a perspective view showing a part of the sheet conveying apparatus 70. FIG. 11 is a cross-sectional view illustrating a process of removing the double feed prevention unit 32 of the sheet conveying apparatus 70. In the following description, the same components as those of the sheet conveying device 5 according to the first embodiment are denoted by the same reference numerals, and the same description is omitted.

  As shown in FIGS. 10 and 11, the sheet conveying apparatus 70 according to the second embodiment omits the separation assisting spring 35 and includes a notch portion 71 in the guide surface portion 52 of the second holder 42. This is different from the sheet conveying apparatus 5 according to the first embodiment.

  As shown in FIG. 10, the notch portion 71 is recessed from the left edge portion (upstream side) to the right side (downstream side) on the rear side of the guide surface portion 52. The cutout portion 71 is formed by cutting out the edge portion of the guide surface portion 52 located on the accommodation space SP1 side in a substantially rectangular shape when viewed from the plane. The notch 71 is formed to form a space (hereinafter referred to as “operation space SP2”) between the retard roller 40 (torque limiter 40a).

  Next, with reference to FIG. 11, a replacement operation of the double feed preventing unit 32 in the sheet conveying apparatus 70 will be briefly described. Note that a description of the same procedure as that of the sheet conveying device 5 according to the first embodiment is omitted.

  First, the operator pushes the retard roller 40 to release the engagement between the second holder 42 and the hook portion 34. Subsequently, the operator inserts a finger into the operation space SP <b> 2 and hooks the finger on the edge of the notch 71. Then, the operator picks up the edge (guide surface portion 52) of the cutout portion 71 and lifts the double feed prevention portion 32. As described above, the double feed preventing portion 32 is removed from the accommodating portion 60. According to the sheet conveying device 70, the replacement work of the multifeed preventing portion 32 can be smoothly performed by merely cutting out a part of the second holder 42.

  In addition, although illustration is abbreviate | omitted, the notch part 71 may be formed in the 2nd holder 42 of the sheet conveying apparatus 5 which concerns on 1st Embodiment.

  In the sheet conveying devices 5 and 70 according to the first and second embodiments, the inclined surface 64b slidably contacting the contact portion 48 is formed in the claw portion 64 of the hook portion 34, but the present invention is not limited to this. For example, the inclined surface 64b of the hook part 34 may be deleted, and the abutting part 48 may have an inclined surface (not shown) for slidingly contacting the tip part of the hook part 34.

  In the above-described replacement operation of the double feed preventing unit 32, the entire double feed preventing unit 32 is replaced. However, the present invention is not limited to this. For example, the retard roller 40 and the first holder 41 may be replaced and the second holder 42 may be reused. In addition, only the retard roller 40 may be replaced, and the holders 41 and 42 may be reused.

  The description of the above embodiment shows one aspect of the sheet conveying apparatus according to the present invention and an image forming apparatus including the same, and the technical scope of the present invention is not limited to the above embodiment. . The components in the above embodiment can be appropriately replaced or combined with existing components and the like, and the description of the above embodiment does not limit the content of the invention described in the claims. .

1 Printer (image forming device)
2 Device body 3 Paper feed cassette 5,70 Sheet conveyance device 31c Conveyance roller 33 Conveyance guide portion 34 Hook portion 35 Detachment assisting spring (detachment assisting member)
40 retard roller 41 first holder 42 second holder 43 nip forming spring (biasing member)
48 Contact portion 52 Guide surface portion 60 Storage portion 64b Inclined surface 71 Notch portion P1 Engagement position P2 Release position S Sheet

Claims (5)

The device body;
A conveyance guide unit provided in the apparatus main body on the downstream side of the sheet storage unit for storing sheets;
A transport roller disposed above the transport guide and transporting the sheet;
A retard roller pressed against the transport roller;
A first holder for rotatably supporting the retard roller;
A biasing member that biases the retard roller toward the transport roller via the first holder;
A second holder that rotatably supports the first holder;
An accommodating portion that is provided in the conveyance guide portion and detachably accommodates the second holder;
An engagement position which is provided in the housing portion and is set to a position for engaging with the second holder housed in the housing portion; and a release position which is set to a position for releasing the engagement with the second holder; A hook portion provided so as to be elastically deformable between,
The first holder includes a contact portion that presses the hook portion from the engagement position toward the release position when the first holder is pushed against a biasing force of the biasing member. Sheet conveying device. A disengagement assisting member that urges the second holder in a direction to disengage the second holder from the accommodating portion;
2. The sheet conveying apparatus according to claim 1, wherein the second holder is urged by the detachment assisting member to be detached from the accommodating portion when the hook portion is displaced to the release position. The second holder has a guide surface portion on the downstream side of the retard roller,
The sheet conveying apparatus according to claim 1, wherein the guide surface portion includes a notch portion that is notched downstream from an edge portion facing the retard roller.   Either the hook part or the contact part is inclined toward the release position side from the downstream side in the pushing direction of the first holder toward the upstream side, and either the hook part or the contact part is The sheet conveying apparatus according to claim 1, further comprising an inclined surface that is in sliding contact. An image forming apparatus comprising the sheet conveying device according to claim 1.

Images