JP2007112550A - Sheet cassette, sheet feeding apparatus, and image forming apparatus - Google Patents

Abstract

An object of the present invention is to control the leading end of a sheet and the leading end of the sheet when the sheet cassette is mounted on the apparatus main body without being affected by the force of the user who mounts the cassette on the apparatus main body or the paper type. It is to ensure a gap between the inner walls.
A sheet cassette 2 is detachably mounted in a conveying direction of a sheet S with respect to an apparatus main body 1 and the stacked sheets S are provided on the apparatus main body side after being mounted on the apparatus main body 1. The sheet stacking member 21 is provided so as to be rotatable so as to be brought into contact with the pick-up roller 3, and before being mounted on the apparatus main body 1, the sheet stacking member 21 is positioned at a restriction position for restricting the leading edge of the sheet S. And a leading edge restricting member 25 that moves to a restriction releasing position that is spaced apart from the leading edge of the sheet S.
[Selection] Figure 2

Description

  The present invention relates to a sheet cassette that is detachably attached to a sheet feeding apparatus and an image forming apparatus.

  2. Description of the Related Art Conventionally, a sheet feeding device such as a feeding deck and an image forming apparatus (hereinafter referred to as an apparatus main body) such as a printer and a copying machine include a sheet cassette that is detachably mounted. In some cassettes, when mounted on the apparatus main body, a sheet stacking plate on which sheets are stacked rotates, and the leading end of the sheet is pressed against a pickup roller that feeds the sheet. In such a cassette, a displaceable rear end restricting plate for restricting the rear end position of the sheet, a cassette inner wall for restricting the front end position of the sheet, and a displaceable width restricting plate for restricting the end position in the width direction of the sheet. In general, the sheet is positioned.

  In the cassette having the above configuration, a certain gap is provided between the trailing edge of the sheet and the trailing edge regulating plate, and the sheet moves to the trailing edge regulating plate side due to inertia when mounted on the apparatus body, and the leading edge of the sheet is fed. There is one in which a gap is provided between the inner wall of the cassette (see, for example, Patent Document 1). This is to avoid fluctuations in the feeding pressure (contact pressure between the pickup roller and the sheet) due to contact between the front end of the sheet lifted by the sheet stacking plate that is rotated when the apparatus is mounted on the apparatus body and the inner wall of the cassette.

  Hereinafter, a conventional sheet cassette having a configuration in which a gap is provided between the leading end of the sheet and the inner wall of the cassette will be described with reference to FIG.

  On the bottom wall of the cassette 101, a groove 106 that meshes with the rear end regulating plate 111 is provided in a sawtooth shape. The pedestal portion 113 of the rear end regulating plate 111 is provided with a projection 105 that meshes with the groove 106 in the cassette bottom wall. The protrusion 105 is engraved in a slide block 104 fitted to the pedestal portion 113 so as to be displaceable in the direction of arrow FG, and a biasing member 112 is provided between the pedestal portion 113 and the slide block 104. .

  When the stacked sheets 107 are stored in the cassette 101 and the trailing end regulating plate 111 is moved in the arrow G direction, an external force in the arrow G direction is applied to the sheet regulating unit 110. Then, the rear end restricting plate 111 is inclined with respect to the bottom wall of the cassette while resisting the restoring force of the engaging portion 103, and the slide block 104 engaged with the groove 106 of the cassette resists the drag of the urging member 112. To move in the direction of arrow F. As a result, as shown in FIG. 5B, when the gap 114 is formed between the slide block 104 and the force with the biasing member 112 is balanced, the projection 105 and the groove 106 are disengaged, and the rear end The restriction plate 111 moves in the direction of arrow G.

  When the sheet restricting portion 110 of the rear end restricting plate 111 comes into contact with the rear end of the sheet 107, the aforementioned external force is removed. Then, the rear end regulating plate 111 is returned in the direction of arrow F by the restoring force of the engaging portion 103 and the biasing member 112. Then, when the gap 114 generated between the slide block 104 is eliminated, the groove 106 and the projection 105 are engaged with each other as shown in FIG. A gap 108 is formed in

  Accordingly, when the cassette 101 is mounted in the apparatus main body (in the direction of arrow F) in this state, an inertial force acts on the sheet 107 and the sheet 107 moves in the direction of arrow F. As a result, the rear end of the sheet 107 is brought into contact with the sheet restricting portion 110 of the rear end restricting plate 111, and as a result, a gap is generated between the front end of the sheet 107 and the inner wall of the cassette 101. This gap prevents the front end of the sheet 107 from contacting the inner wall of the cassette 101 when the sheet stacking plate 102 rotates and the sheet 107 is lifted.

JP 2003-95446 A

  However, in the above conventional example, as a means for providing a gap between the sheet front end and the inner wall of the cassette, an inertial force acting on the sheet, that is, a user's force for mounting the cassette on the apparatus main body is used. There was a problem.

  For example, when the user slowly sets the sheet cassette on the apparatus main body, or when a light weight (small inertia) sheet is accommodated in the cassette, the sheet may not move to the rear end regulating plate side.

  Further, even if the sheet moves to the rear end regulating plate side, it does not always move in a state where the bundled sheets accommodated in the cassette are aligned. For example, only the upper layer sheet of the bundle-like sheet moves, and the lower layer sheet may not move and remain in the original position. Therefore, a sufficient gap is not provided between the sheet front end and the cassette inner wall, and the feeding pressure due to the contact between the front end of the sheet lifted by the sheet stacking plate and the cassette inner wall fluctuates, resulting in problems such as poor paper feeding. Has occurred.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sheet front end and a cassette inner wall that regulates the front end of the sheet when the sheet cassette is mounted on the apparatus main body without being affected by the force of the user who mounts the cassette on the apparatus main body or the paper type. It is to make sure to provide a gap between them.

  In order to achieve the above object, a representative configuration of the present invention is a sheet cassette that is detachably mounted along the sheet conveyance direction with respect to the image forming apparatus main body or the sheet feeding apparatus main body. After loading on the main body, a sheet stacking member provided so as to be able to rotate so that the stacked sheets are brought into contact with the sheet feeding means provided on the apparatus main body side, and before mounting on the apparatus main body. And a leading edge regulating member that is positioned at a regulating position that regulates the leading edge of the sheet and moves to a regulation release position that is separated from the leading edge of the sheet by the mounting operation to the apparatus main body.

  According to the present invention, when the sheet cassette is mounted on the apparatus main body without being affected by the force of the user who mounts the sheet cassette on the apparatus main body or the paper type, A gap is surely provided between the two. Thereby, when the sheet stacking member rotates and the sheet is lifted, the contact resistance between the sheet leading end and the leading end regulating member can be eliminated. For this reason, the uppermost sheet on the sheet stacking member can be brought into pressure contact with the sheet feeding means with a constant feeding pressure, and stable sheet feeding can be performed.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
As an image forming apparatus having a sheet cassette according to the first embodiment, a laser beam printer (hereinafter simply referred to as a printer) will be described as an example. In the following description, the schematic configuration of the printer will be described first, and then the details of the sheet cassette will be described.

  First, the schematic configuration of the printer will be described with reference to FIG. FIG. 4 is a schematic sectional view of the printer.

  In FIG. 4, reference numeral 1 denotes a printer main body, and a sheet cassette 2 on which a sheet is placed and stored is detachably attached to a lower portion (feeding unit 20). The sheet cassette 2 is configured to be drawable in the sheet conveyance direction with respect to the printer main body 1. The sheet cassette 2 is configured to accommodate sheets of different sizes. The sheet cassette 2 will be described in detail later.

  The sheets accommodated in the sheet cassette 2 are fed by rollers 3, 4, and 5 that constitute sheet feeding means. Reference numeral 3 denotes a pick-up roller that selectively and appropriately sends out the sheet placed on the sheet cassette 2 from the uppermost side. 4 is a feed roller, and 5 is a retard roller, which separates and feeds the sheets fed by the pickup roller 3 one by one.

  The sheet fed by the feed roller 4 is conveyed toward the registration roller pair 8 by the conveyance roller pairs 6 and 7. With the registration roller pair 8 stopped, skew is corrected by forming a loop by bringing the leading edge of the sheet conveyed by the conveyance roller pair 7 into contact with the nip portion of the registration roller pair 8. The skew-corrected sheet is conveyed by the registration roller pair 8 to a nip portion between the photosensitive drum 11 in the process cartridge 10 constituting the image forming unit and the transfer roller 9 opposed thereto at a predetermined timing. The

  In addition to the photosensitive drum 11, the process cartridge 10 incorporates known process means (charging means 12, developing means 14, cleaning means 15) and is detachably attached to the printer body 1. ing. A laser exposure optical system 13 forms an electrostatic latent image by irradiating the uniformly charged surface of the photosensitive drum 11 with laser light corresponding to image information. To the photosensitive drum 11 on which the electrostatic latent image is formed, toner is applied by the developing means 14 in the process cartridge 10 to form a toner image.

  Then, in synchronization with the rotation of the photosensitive drum 11, the sheet is conveyed to the nip portion between the photosensitive drum 11 and the transfer roller 9 by the registration roller pair 8, and is formed on the surface of the photosensitive drum 11 by the action of the transfer roller 9. The toner image thus transferred is transferred.

  The sheet on which the toner image has been transferred is heated and pressurized when passing through the fixing device 16 to permanently fix the toner image on the sheet. The sheet on which the toner image is fixed is discharged onto a discharge tray 18 formed on the upper surface of the printer main body 1 by a discharge roller pair 17.

  Next, details of the sheet cassette 2 will be described with reference to FIGS. 1 and 2. FIG. 1A is a perspective view of a sheet cassette and a printer main body feeding unit for mounting the sheet cassette. FIG. 1B is a perspective view of the leading edge regulating member of the sheet cassette in the first embodiment. 2A and 2B are schematic cross-sectional views of the sheet cassette showing the operation of the leading end regulating member. FIG. 2A shows a state before mounting and FIG. 2B shows a state after mounting.

  In FIG. 1A, the sheet cassette 2 is provided with a sheet stacking member 21 that is rotatable about a support shaft 22 that is planted on both side walls 2a of the cassette. The sheet stacking member 21 is rotatable so that the sheet S in the cassette 2 comes into contact with the pickup roller 3 on the printer body side after the cassette 2 is mounted on the printer body feeding unit 20.

  Further, the sheet cassette 2 has a width regulating member 23 that regulates the positions of both ends in the width direction orthogonal to the conveying direction of the sheets S stacked on the sheet stacking plate 21. The width regulating member 23 is movable in the width direction of the sheet S with reference to the central portion of the cassette, and is moved in the width direction according to the size of the sheet S to regulate the positions of both ends of the sheet S in the width direction. The sheet cassette 2 includes a rear end regulating member 24 that regulates the position of the rear end in the transport direction of the sheet S in the cassette. The trailing edge regulating member 24 is movable in the conveyance direction of the sheet S, and is moved in the conveyance direction according to the size of the sheet S to regulate the position of the trailing edge in the conveyance direction of the sheet S.

  Further, the sheet cassette 2 has a leading end regulating member 25 that regulates the position of the leading end in the transport direction of the sheet S in the cassette. The tip regulating member 25 is provided with an integrated shaft 25a, and protrudes to the outside (both sides) of the cassette from a long hole 2c provided in both side walls 2a of the cassette. The leading end regulating member 25 has an integrated shaft 25a that can move in the sheet conveying direction along the long hole 2c of the side wall 2a. Further, the tip regulating member 25 is biased by a coil spring (biasing member) 26 so that the tip regulating surface 25b protrudes inward from the cassette inner wall 2b. That is, the front end regulating member 25 is positioned at a regulating position (see FIG. 2A) that regulates the front end of the sheet S before the cassette 2 is mounted on the printer main body feeding unit 20. The leading edge restricting member 25 is configured to be movable to a restriction releasing position (see FIG. 2B) that is separated from the leading edge of the sheet S by the mounting operation of the cassette 2 to the printer main body feeding unit 20.

  As shown in FIG. 1B, the leading edge regulating member 25 has a leading edge regulating surface 25b that regulates the leading edge of the sheet. The leading edge regulating surface 25b is divided and provided in the width direction of the sheet. In this example, the front end regulating surface 25b is divided into two in the width direction of the sheet.

  Further, as shown in FIG. 1A, an insertion hole 2d through which the leading end regulating surface 25b of the leading end regulating member 25 passes is provided in the cassette inner wall 2b on the leading end side of the sheet cassette 2. The leading edge regulating surface 25b of the leading edge regulating member 25 passes through the insertion hole 2d of the cassette inner wall 2b and protrudes from the cassette inner wall 2b to regulate the sheet leading edge, or retracts into the cassette inner wall 2b and extends between the leading edge of the sheet. Create a gap in

  The feeding unit 20 of the printer main body 1 is provided with a restriction releasing member 27 for releasing the restriction by the leading edge restricting member 25 of the sheet cassette 2. The restriction release member 27 is provided on both side walls 20a of the printer main body 1, and is arranged so that the shaft 25a of the tip restriction member 25 is received by the groove portion. Then, the restriction release member 27 moves the tip restriction member 25 located at the restriction position (see FIG. 2A) to the restriction release position (FIG. 2B by attaching the cassette 2 to the printer body 1). ) Refer to).

  Next, the operation of the leading end regulating member 25 due to the mounting operation of the sheet cassette 2 will be described in detail. As shown in FIG. 2A, in the sheet cassette 2 before being mounted on the printer main body 1, the leading end regulating member 25 regulates the position of the leading end of the sheet at the regulating position. That is, the leading edge regulating member 25 is urged by the coil spring 26, and the stacked sheets S are positioned at a position where the leading edge regulating surface 25b protrudes from the cassette inner wall 2b to the sheet side by a predetermined distance (about 1 to 2 mm in this example). The tip of the is regulated. Further, the rear end of the sheet S is regulated by the rear end regulating member 24, and the width direction side end of the sheet S is regulated by the width regulating member 23.

  When the sheet cassette 2 is attached to the printer main body 1 from this state, as shown in FIG. 2B, the leading end regulating member 25 of the sheet cassette 2 is moved to the regulation release position by the regulation release member 27 on the printer body side. The That is, the shaft 25a of the leading end regulating member 25 is received by the groove portion of the regulating releasing member 27, and the leading end regulating member 25 that regulates the sheet leading end at the regulating position shown in FIG. Thus, the leading end regulating surface 25b is relatively moved to the regulation releasing position retracted into the cassette inner wall 1b. At this time, a gap t is formed between the leading edge of the sheet S and the inner wall 2 b of the cassette 2. Since this gap t is determined by the leading end regulating member 25 and the cassette inner wall 2b at the time of protrusion, a constant gap (about 1 to 2 mm in this example) can always be generated reliably.

  After the sheet cassette 2 is mounted on the printer main body 1, the sheet stacking member 21 rotates and the uppermost layer of the sheet S is pressed against the pickup roller 3. When the sheet stacking member 21 is rotated, there is no member that contacts the leading edge of the sheet, so that the sheet S can be brought into pressure contact with the pickup roller 3 with a stable rotation operation and feeding pressure. Then, the sheet S is fed out by the rotation of the pickup roller 3, and the uppermost sheet is fed out by the friction separation method.

  As described above, according to the present embodiment, when the cassette 2 is mounted on the printer main body 1, the gap t is reliably provided between the sheet leading end on the sheet stacking member 21 and the leading end regulating member 25. Thereby, when the sheet stacking member 21 rotates and the sheet S is lifted, there is no contact resistance between the leading end of the sheet and the leading end regulating member 25. Therefore, the uppermost sheet on the sheet stacking member 21 can be pressed against the pickup roller 3 with a constant feeding pressure, and stable feeding can be performed.

  Further, when the cassette is loaded, the leading edge regulating member 25 moves in a direction away from the leading edge of the sheet, and a gap t is generated between the leading edge of the sheet and the leading edge regulating member 25. For this reason, the above-described effects can be reliably obtained without being affected by the force of the user who mounts the cassette 2 on the printer body 1 or the paper type.

[Second Embodiment]
A sheet cassette according to the second embodiment will be described with reference to FIG. FIG. 3A is a perspective view of a sheet cassette according to the second embodiment. FIG. 3B is a perspective view of the tip regulating member according to the second embodiment. In addition, since the sheet cassette 2 in this embodiment is a structure substantially equivalent to 1st Embodiment mentioned above, the same code | symbol is attached | subjected to the member which has an equivalent function, and the detailed description is abbreviate | omitted.

  In the first embodiment described above, the configuration in which the leading end regulating member 25 has the leading end regulating surface 25b divided in the sheet width direction is exemplified. However, in the second embodiment, a plurality of leading end regulating members 25 are provided in the sheet width direction. It has the structure which has the front-end | tip control rib 25c. That is, in the present embodiment, as shown in FIG. 3A, the leading end of the sheet is regulated by a plurality of ribs instead of the plate surface.

  In addition, about operation | movement of the front-end | tip regulating member 25 in this embodiment, it is the same as that of the front-end | tip regulating member in embodiment mentioned above. As shown in FIG. 3B, before the attachment to the printer main body 1, the leading edge regulating member 25 is positioned at the regulating position where the leading edge regulating rib 25c protrudes from the cassette inner wall 2b to the sheet side by a predetermined distance. Regulate the tip position. When the cassette 2 is mounted on the printer main body 1, the shaft 25a integrated with the front end regulating member 25 is received by the restriction releasing member 27 provided on the printer main body 1, and the front end regulating rib 25c is formed on the cassette inner wall 2b. Moved to the restriction release position retracted inside. As a result, a gap t is generated between the cassette inner wall 2b and the sheet leading edge, and the friction resistance at the sheet leading edge is eliminated, so that the sheet stacking member 21 can be reliably rotated and the sheet lifted, and the printer can be supplied with a stable feeding pressure. Can be fed to the main unit.

  In the first embodiment, when there are many types of widths of sheets to be accommodated, it is necessary to increase the front end regulating surface of the front end regulating member, and it is also necessary to increase the hole in the inner wall of the cassette. On the other hand, according to the second embodiment, a plurality of different kinds of sheet widths can be accommodated by the plurality of front end regulating ribs. Furthermore, the hole on the inner wall of the cassette may have a thin shape that matches the rib, and can accommodate a larger sheet width size without impairing the rigidity of the cassette.

[Other Embodiments]
In the above-described embodiment, the printer is exemplified as the image forming apparatus. However, the present invention is not limited to this, and may be another image forming apparatus such as a copying machine or a facsimile machine. Alternatively, the image forming apparatus may be another image forming apparatus that combines these functions. A similar effect can be obtained by applying the present invention to a sheet cassette that is detachably mounted on these image forming apparatuses.

  Further, in the above-described embodiment, the sheet cassette that is detachable from the image forming apparatus is exemplified, but the present invention is not limited to this. For example, a sheet feeding device such as a feeding deck as an optional unit that is detachable from the image forming apparatus may be used. That is, the sheet cassette may be detachable, and may be a sheet feeding device provided with sheet feeding means for feeding a sheet from the cassette, and the same effect can be obtained by applying the present invention to the sheet feeding device. be able to.

FIG. 4A is a perspective view of a sheet cassette according to the first embodiment and a printer main body feeding unit that mounts the sheet cassette. FIG. 5B is a perspective view of a front end regulating member according to the first embodiment. It is a schematic cross section which shows operation | movement of the front-end | tip control member in a sheet cassette, (a) shows before mounting and (b) shows after mounting. FIG. 5A is a perspective view of a sheet cassette according to a second embodiment and a printer main body feeding unit for mounting the sheet cassette, and FIG. 5B is a perspective view of a front end regulating member according to the second embodiment. It is a schematic cross section of a printer having a sheet cassette. It is a figure explaining a prior art example.

Explanation of symbols

S ... sheet t ... gap 1 ... printer body 2 ... sheet cassette 2a ... side wall 2b ... cassette inner wall 2c ... long hole 2d ... insertion hole 3 ... pickup roller 4 ... feed roller 5 ... retard rollers 6, 7 ... conveying roller pair 8 ... Registration roller pair 9 ... transfer roller 10 ... process cartridge 11 ... photosensitive drum 12 ... charging means 13 ... laser exposure optical system 14 ... developing means 15 ... cleaning means 16 ... fixing device 17 ... discharge roller pair 18 ... discharge tray 20 ... main body Feed unit 21 ... sheet stacking member 22 ... support shaft 23 ... width regulating member 24 ... rear end regulating member 25 ... tip regulating member 25a ... shaft 25b ... tip regulating surface 25c ... tip regulating rib 26 ... coil spring 27 ... regulation release member

Claims (10)

A sheet cassette that is detachably attached to the image forming apparatus main body or the sheet feeding apparatus main body along a sheet conveyance direction,
A sheet stacking member provided so as to be able to rotate in order to bring the stacked sheets into contact with the sheet feeding means provided on the apparatus main body side after being mounted on the apparatus main body;
A front end regulating member that is positioned at a regulation position that regulates the front end of the sheet before being attached to the apparatus main body, and is moved to a restriction release position that is separated from the front end of the sheet by the attaching operation to the apparatus main body;
A sheet cassette characterized by comprising:   2. The sheet cassette according to claim 1, wherein the leading edge regulating member has a leading edge regulating surface that can project to a sheet side from a hole provided in an inner wall on a downstream side in a sheet conveying direction.   The sheet cassette according to claim 1, wherein the leading edge regulating member regulates the leading edge of the sheet by a plurality of leading edge regulating ribs provided in the sheet width direction. A sheet feeding device having a sheet cassette that is detachable along a sheet conveyance direction with respect to the apparatus main body, and a sheet feeding unit that feeds a sheet from the cassette,
A sheet stacking member that is provided in the sheet cassette and is rotatably provided to bring the stacked sheets into contact with the sheet feeding means after being mounted on the apparatus main body;
A front end regulating member provided in the sheet cassette and movable to a regulation position for regulating the front end of the sheet and a regulation release position spaced apart from the front end of the sheet;
A restriction release member that is provided on the apparatus main body side and moves a tip restriction member positioned at the restriction position to the restriction release position by an attachment operation to the apparatus main body;
A sheet feeding apparatus comprising:   The sheet feeding apparatus according to claim 4, wherein the sheet feeding apparatus is detachable from an image forming apparatus that forms an image on a sheet.   The sheet feeding device according to claim 4, wherein the leading edge regulating member has a leading edge regulating surface that can project to a sheet side from a hole provided in an inner wall of the cassette.   The sheet feeding apparatus according to claim 4 or 5, wherein the leading edge regulating member regulates the leading edge of the sheet by a plurality of leading edge regulating ribs provided in the sheet width direction. A sheet cassette that is detachable from the apparatus main body along a sheet conveyance direction, a sheet feeding unit that feeds a sheet from the sheet cassette, and an image forming unit that forms an image on the sheet fed from the sheet cassette; An image forming apparatus having
A sheet stacking member provided in the sheet cassette and rotatably provided so that the sheets stacked after being mounted on the apparatus main body are brought into contact with the sheet feeding unit;
A front end regulating member provided in the sheet cassette and movable to a regulation position that regulates the front end of the sheet and a regulation release position that is separated from the front end of the sheet;
A restriction release member that is provided on the apparatus main body side and moves a tip restriction member positioned at the restriction position to the restriction release position by an attachment operation to the apparatus main body;
An image forming apparatus comprising:   The image forming apparatus according to claim 8, wherein the leading end regulating member has a leading end regulating surface that can project toward a sheet side from a hole provided in an inner wall of the cassette.   The image forming apparatus according to claim 8, wherein the leading edge regulating member regulates the leading edge of the sheet by a plurality of leading edge regulating ribs provided in the sheet width direction.

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