JP2012006678A - Sheet feeding device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeding device which can warp a sheet by performing one or less pick-up roller used to be performed two pick-up rollers as separating devices of the sheet for the operation.SOLUTION: The sheet feeding device includes: a sheet conveying means contacting the loaded sheet, rotating and conveying the sheet; a wear member contacting to the loaded sheet; and a separation unit having a wear member contacting the sheet conveying means to form a nip part to separately convey a sheet one by one at the nip part. A displacement is added to the loaded sheet by changing the distance between the nip part and the wear member before starting to rotate the sheet conveying means.

Description

  The present invention relates to a sheet feeding apparatus and an image forming apparatus including the sheet feeding apparatus, and more particularly to an apparatus that separates and feeds sheets one by one by a separating member.

  As a conventional sheet separating apparatus, as shown in Patent Document 1, a mechanism that separates two or more stacked documents into one sheet by a feed roller that conveys the document and a friction pad that contacts the feed roller and forms a nip. However, if a plurality of documents are in close contact, the document may not be separated into one sheet. Therefore, Patent Documents 2 and 3 disclose inventions in which originals are curled by bending the stacked originals so that separation can be correctly performed even with strongly adhered originals.

  However, in the case of Patent Document 2 and Patent Document 3, since two pickup rollers are used, there is a problem in that it is disadvantageous in terms of cost. Therefore, the present invention has been made in view of such a current situation, and a sheet feeding apparatus capable of performing an operation of bending a document, which has been performed by two pickup rollers, with one or less pickup rollers, and the same. An object of the present invention is to provide an image forming apparatus provided with the above.

  The sheet feeding apparatus of the present invention forms a nip portion in contact with a sheet conveying unit that contacts and rotates to convey a sheet, a wear member that contacts the stacked sheet, and a sheet conveying unit. A sheet feeding device that separates and feeds sheets one by one at the nip portion, and before the sheet conveying means starts rotating, the nip portion and the wear member Displacement is added to the stacked sheets by changing the distance.

  According to the present invention, in the sheet separation mechanism, the distance between the nip portion and the wear member is changed before the separation of the sheet is started, and two or more sheets that are in close contact with each other are pulled apart by giving a displacement to the sheet. The sheet can be reliably separated at the nip portion.

1 is a schematic cross-sectional view illustrating a configuration of an image reading apparatus including a sheet feeding device according to an embodiment of the present invention. FIG. 3 is a detailed view (part 1) of the sheet feeding apparatus according to the embodiment of the present invention. FIG. 5 is a detailed view (No. 2) of the sheet feeding apparatus according to the embodiment of the present invention. FIG. 6 is a detailed view (No. 3) of the sheet feeding apparatus according to the embodiment of the present invention. FIG. 6 is a detailed view (No. 4) of the sheet feeding apparatus according to the embodiment of the present invention. FIG. 10 is a detailed view (No. 5) of the sheet feeding apparatus according to the embodiment of the present invention. FIG. 10 is a detailed view (No. 6) of the sheet feeding apparatus according to the embodiment of the present invention. FIG. 10 is a detailed view (No. 7) of the sheet feeding apparatus according to the embodiment of the present invention. FIG. 10 is a detailed view (No. 8) of the sheet feeding apparatus according to the embodiment of the present invention. It is detail drawing (the 9) of the sheet | seat separation operation | movement which concerns on embodiment of this invention. It is detail drawing (the 10) of sheet | seat separation operation | movement which concerns on embodiment of this invention. It is a flowchart figure of the sheet | seat separation operation | movement which concerns on embodiment of this invention. It is the figure of the timeline which showed each step of sheet separation operation concerning an embodiment of the present invention along a time axis.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be changed as appropriate according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended that the scope of the present invention be limited to the following embodiments.

  First, the first embodiment will be described. FIG. 1 is a schematic cross-sectional view illustrating a configuration of an automatic image reading apparatus as a sheet processing apparatus including a sheet feeding apparatus according to the first embodiment. The automatic image reading apparatus 1 conveys a bundle of documents stacked on a document tray 2 to a separation nip between a separation unit 4 and a feed roller 5 by a pickup roller 3 and separates only the top sheet of the document bundle. . Documents separated by the separation unit 4 or the like are conveyed one by one along a conveyance path formed between the separation nip, the pull-out roller 6, the pre-reading roller 7, and the paper discharge roller 10.

  The uppermost document separated into one sheet by the separation nip is conveyed between the pull-out roller 6a and the driven roller 6b by the rotation of the feed roller 5. Since the conveyance speed of the pull-out roller 6 is higher than the conveyance speed of the feed roller 5, a torque limiter is attached to the feed roller 5, and the document is rotated at the conveyance speed of the pull-out roller 6 after the document reaches the pull-out roller 6. It can be operated.

  The document that has reached the pull-out roller 6 is conveyed along the conveyance path to the image reading unit between the background plate 8 and the image reading unit 9 via the pre-reading roller 7a and the driven roller 7b, and an image is read.

  In the case of single-sided reading, the original that has passed through the image reading unit is sent to the paper discharge tray 13 via the paper discharge roller 10a and its driven roller 10b. In the case of double-sided reading, the branching claw 11 moves, the document is conveyed from between the paper discharge roller 10a and its driven roller 10b to the reversing roller 12a and its driven roller 12b, and thereafter between the paper discharge roller 10a and its driven roller 10c. Then, the image is read to the pre-reading roller 7 and the image is read in the same manner as when reading on one side.

  However, if the original is sent out to the paper discharge tray 13 as it is after the back side image is read, the setting direction of the front and back of the original is opposite to that when the original is set on the original tray 2, and therefore the path transported at the time of double-sided reading again. After that, the document is sent to the abolition tray 13.

  Next, details of the sheet feeding apparatus according to the present embodiment will be described with reference to FIGS. 2, 3, 4, 5, 6, 7, 8, 9, 12, and 13. The pickup roller 3 is fixed to the holder by a shaft and holding members 31a and 31b as shown in the figure. The holder has a hole so that the pickup roller 3 can be moved, and the force is received in a direction away from the feed roller 5 by the elastic bodies 3d and 3e. Examples of the elastic bodies 3d and 3e include compression spring leaf springs. In particular, a compression spring is preferable from the viewpoint of installation space.

  FIG. 5 shows an example of how the elastic bodies 3d and 3e are installed. The elastic body 3 d is in contact with a part of the holder and the gear 32 b and acts in a direction in which the pickup roller 3 is separated from the feed roller 5. Further, the elastic body 3e is in contact with a part of the holder and the holding member 31b, and similarly acts in a direction in which the pickup roller 3 is separated from the feed roller 5. Here, although it seems that the elastic body 3d and the gear 32b are in contact, in reality, a spacer (not shown) made of a material such as resin is provided between the elastic body 3d and the gear 32b so as not to prevent the rotation of the gear 32b. The frictional resistance generated between the elastic body 3d and the gear 32b is reduced.

  The rotation of the shaft of the feed roller 5 is transmitted to the pickup roller 3 by gears 32a, 32b, 32c, 32d and a shaft 32e. The shaft 32e has a hole so that the gear 32b can be moved. However, the gear 32b is pressed against the shaft 32a by the elastic body 3d, so that the gears 32b and 32a are always in contact with each other. . In FIG. 9, some shapes and parts are removed for the sake of simplicity.

  A gear 3b is attached to the shaft of the pickup roller 3 via a torque limiter 3a and is in contact with the tooth portion of 3c. As a result, the pickup roller 3 moves toward the feed roller 5 due to the rotation at the time of paper feeding. However, since the torque limiter 3a is attached to the gear 3b, the pickup roller 3 stops at a position that balances the force of the elastic bodies 3d and 3e. When the paper feeding is completed, the force applied to the gear 3b disappears, and the pickup roller 3 is returned to the original position by the force of the elastic bodies 3d and 3e. Note that FIG. 8 is drawn with the tooth portions of the gears 3b and 3c that are originally in contact with each other separated for ease of explanation.

  The feed roller 5 is not directly fixed to the shaft, and the rotation is started by causing the gear 51b to engage the gear 51a by the rotation of the gear 51c fixed to the shaft. Therefore, the feed roller 5 is delayed from the start of the shaft rotation. Start rotating. As a result, it is possible to start the rotation of the feed roller 5 after the pickup roller 3 finishes moving, and the stacked originals can be bent by the movement of the pickup roller 3 at the start of feeding. 6 and 7 are arranged so that the parts are separated from each other for the sake of simplicity.

  Next, the separation operation of the closely attached sheets will be described using the flowchart of FIG. With the above configuration, when the paper feed shaft of the feed roller 5 starts rotating at the start of paper feed (step S1201), the pickup roller 3 transmits the rotation of the paper feed shaft through the gears 32a, 32b, 32c, 32d, and the shaft 32e. (Step S1210), and immediate rotation is started (step S1211).

  However, the feed roller 5 is not directly connected to the paper feed shaft, but has a mechanism in which rotation is transmitted by the gear 51 (step S1220), and the gear 51 is transmitted until the gears mesh with each other (step S1221). Since there is no mechanism, a delay occurs in the start of rotation of the feed roller 5 (step S1222).

On the other hand, when the pickup roller 3 starts rotating, the gear 3b meshing with the teeth of 3c also rotates at the same time, so that the pickup roller 3 starts moving simultaneously with the start of rotation of the feed shaft of the feed roller 5 (step S1212). . Since the sheets stacked by the movement of the pickup roller 3 are abutted against the nip portion between the feed roller 5 and the separation unit 4, the sheets are bent, and two or more closely contacted sheets are separated (step S <b> 1213).
Further, the pickup roller 3 moves toward the feed roller 5, but since the torque limiter 3a is attached to the gear 3b, the pickup roller 3 stops at a position that balances the force of the elastic bodies 3d and 3e (step S1214).

  Therefore, the pickup roller 3 starts to move simultaneously with the start of sheet feeding, causing the stacked sheets to bend. Thereafter, when the gear 51 is engaged and the feed roller 5 starts to rotate, the sheet is separated at the nip portion between the feed roller 5 and the separation unit 4 (step S1230), and even if the closely contacted sheet is set, it is picked up in advance. Since the sheet is separated by the movement of the roller 3, the separation can be performed reliably. FIG. 13 is a timeline diagram showing the steps described in FIG. 12 along the time axis.

  Next, Embodiment 2 will be described. 10 and 11 show an embodiment in the case where bending is generated in the width direction of the document. Friction members 30a and 30b are attached to a shaft 30 that rotates in the same direction as the feed roller 5, as shown in the figure. When the shaft 30 rotates during document conveyance, the wear members 30a and 30b are pushed toward the center due to the shape of the shaft 30. It is possible to cause the document to be bent.

  As an effect of the present invention, in the sheet separation mechanism, the change in the distance between the nip portion and the wear member is performed before starting the separation of the sheets, and the two or more sheets that are in close contact with each other are pulled apart by giving displacement to the sheets. The sheet can be reliably separated at the nip portion.

  Further, as an effect of the present invention, in the sheet separation mechanism, since the change in the distance between the nip portion and the wear member can be changed in the conveying direction, the sheet can be displaced, so two or more sheets that are in close contact with each other due to the displacement. Are separated, and the sheet can be reliably separated at the nip portion.

  In addition, as an effect of the present invention, in the sheet separation mechanism, since the change in the distance between two or more wear members can be changed in the width direction of the stacked sheets, the sheets can be displaced, so that the close contact due to the displacement. The two or more sheets thus separated are separated, and the sheets can be reliably separated at the nip portion.

DESCRIPTION OF SYMBOLS 1 Automatic image reader 2 Document tray 3 Pickup roller 3a Torque limiter 3b Gear 3d Elastic body 3e Elastic body 4 Separation unit 5 Feed roller 6 Pull-out roller 7 Pre-reading roller 8 Background plate 9 Image reading part 31a Holding member 31b Holding member 32a Gear 32b gear 32c gear 32d gear 32e shaft 51 gear

JP 2007-137526 A Japanese Patent No. 4343040 JP 2004-217330 A

Claims (4)

Sheet conveying means for contacting and rotating the stacked sheets and conveying the sheets;
A wear member in contact with the stacked sheets;
A separation unit having the friction member that forms a nip portion in contact with the sheet conveying means,
In the sheet feeding apparatus that separates and feeds the sheets one by one at the nip portion,
A sheet feeding device that adds displacement to the stacked sheets by changing a distance between the nip portion and the wear member before the sheet conveying unit starts rotating. The sheet feeding apparatus according to claim 1, wherein a displacement is applied to the stacked sheets by changing a distance between the nip portion and the wear member in a conveyance direction. 2. The feeding device according to claim 1, wherein a displacement is applied to the stacked sheets by changing an interval between two or more wear members in contact with the stacked sheets in a width direction of the stacked sheets. A sheet feeding apparatus characterized by that.   An image forming apparatus comprising the sheet feeding device according to claim 1.

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