JP2006151526A - Paper transport mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper transport mechanism, preventing the inclination of a driving shaft of a transport roller to favorably transport a paper sheet to an image forming part. <P>SOLUTION: This paper transport mechanism 20 includes: a pickup roller 24 for delivering paper sheets stacked on a paper feed cassette 22; a transport roller 25 for nipping the delivered paper sheet in a space up to a pressure roller 26 and transporting the same; a driving source D for driving a driving shaft 24a of the pickup roller 24 and a driving shaft 25a of a transport roller 25 in rotation; a casing 27 rotatably supporting the driving shaft 24a of the pickup roller 24 on the driving source side D from the pickup roller 24 and the driving shaft 25a of the transport roller 25 on the driving source D side from the transport roller 25; and a bracket 30 rotatably supporting the driving shaft 24a of the pickup roller 24 on the opposite side of the driving source D side from the pickup roller 24 and the driving shaft 25a of the transport roller 25 on the opposite side of the driving source D side from the transport roller 25. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a paper transport mechanism for transporting paper loaded in a paper feed cassette to an image forming unit in a facsimile, a copying machine, or the like.

  Some facsimiles, copiers, and the like are equipped with a paper transport mechanism that transports paper loaded in a paper feed cassette to an image forming unit. For example, as shown in FIG. 8, the paper transport mechanism 900 feeds the uppermost paper stacked in the paper feed cassette 901 by a pickup roller 902, and feeds the fed paper to the transport roller (feed) arranged on the downstream side. Roller) 903 and press roller 904 are conveyed toward the image forming unit.

  The press roller 904 is appropriately disposed around the transport roller 903 according to the direction in which the paper is transported, and is attached so as to press the peripheral surface against the peripheral surface of the transport roller 903. On the other hand, the drive shaft 903a of the transport roller 903 is supported in a cantilever manner on the cassette casing 906 via a bearing 905, as shown in FIGS.

  For example, Patent Document 1 discloses a paper feeding device including a conveyance roller in which a drive shaft is supported in a cantilever manner. The drive shaft is supported by a first bearing attached to the rear plate on the rear side of the machine base, and a second bearing attached to a bracket fixed to the front plate and the rear plate. This sheet feeding device replaces the transport roller by inserting the replacement transport roller held by the mounting member from the free end side of the drive shaft into the drive shaft together with the mounting member. A bearing that supports the drive shaft of the pickup roller is provided between the first bearing and the second bearing on the drive shaft of the transport roller.

Patent Document 2 discloses a paper transport mechanism including a transport roller in which a drive shaft is supported in a cantilever manner. The drive shaft is supported by a bearing provided on a frame fixed inside the machine base, and this frame is provided with a bearing that supports the drive shaft of the pickup roller.
JP-A-9-240852 Japanese Patent Laid-Open No. 10-212044

  However, the pressing force from the press roller 904 is asymmetric, and the transport roller 903 always receives this pressing force. In addition, due to a problem in paper conveyance such as double feeding, a stress higher than that in normal use may be applied to the conveyance roller 903. However, since the transport roller 903 is pivotally supported in a cantilever manner, the drive shaft 903a of the transport roller 903 is applied when the pressing force is continuously applied for a long period of time or when a stress greater than that during normal use is applied. May tilt. When the drive shaft 903a of the transport roller 903 is inclined, the sheet transported by the transport roller 903 is skewed, which causes a problem that good image formation cannot be performed in the image forming unit on the downstream side.

  In order to achieve the above object, the paper transport mechanism according to claim 1 nips and transports the picked-up roller that feeds out the paper stacked in the paper feed cassette and the press roller. A transport roller, a drive shaft for driving the pickup roller and a drive source for rotationally driving the drive shaft of the transport roller, and a drive source side of the pickup roller on the drive source side from the pickup roller; A first shaft support member that rotatably supports the drive shaft of the transport roller, and a drive shaft of the pickup roller on a side opposite to the drive source side from the pickup roller, and a drive source side from the transport roller. And a second shaft support member that rotatably supports the drive shaft of the transport roller on the opposite side.

  The sheet conveying mechanism according to claim 2 is characterized in that in the sheet conveying mechanism according to claim 1, the second shaft support member is attached to the first shaft support member.

  The paper transport mechanism according to claim 3 is the paper transport mechanism according to claim 1 or 2, wherein the first shaft support member is a member constituting a cassette casing on which the paper feed cassette is mounted. It is characterized by that.

  According to the paper transport mechanism of claim 1, the drive shaft of the transport roller is configured such that the drive source side of the transport roller is the first shaft support member, and the opposite side of the drive source side of the transport roller is the second shaft support section. Since each material is supported, the conveying roller can be pivotally supported in a both-sided manner. Therefore, it is possible to prevent the drive shaft of the transport roller from being inclined due to the pressing force from the press roller, and it is possible to transport the paper satisfactorily without causing skew in the transported paper. In addition, the drive shaft of the transport roller is supported on the opposite side of the drive source side by the second shaft support member, and the second shaft support member also supports the drive shaft of the pickup roller, so a new member is added. Therefore, it is possible to support the drive shaft of the transport roller in a doubly supported manner without substantially changing the manufacturing cost or the assembly process. Further, since the second shaft support member supports the drive shaft of the pickup roller and the drive shaft of the transport roller, the assembly accuracy between the pickup roller and the transport roller can be improved, so that the paper can be transported better. It becomes.

  According to the paper transport mechanism of the second aspect, since the second shaft support member is attached to the first shaft support member, the assembly property of the pickup roller and the transport roller can be improved.

  According to the paper transport mechanism of the third aspect, since the first shaft support member is a member constituting the cassette casing, the assembly accuracy of the pickup roller and the transport roller with respect to the paper feed cassette can be improved. it can.

  FIG. 1 is a diagram showing an external configuration of a copy / facsimile multifunction peripheral 100 including a paper transport mechanism according to an embodiment of the present invention. As shown in the figure, the copy / facsimile multifunction peripheral 100 includes a document reading unit 1 that reads image data of a document, and an automatic document feeder (hereinafter referred to as “ADF”) that automatically transports a document to a reading position. A presser cover 2 provided with an image forming unit), an operation unit 3 for inputting original reading settings, an image forming unit 4 that forms an image from the read image data and records the image on a sheet, and accommodates the sheet. And a paper feeding unit 5 for supplying paper to the image forming unit 4. Although not shown, the copy / facsimile multifunction peripheral 100 also includes a transmission unit such as a CODEC for transmitting image data. The configuration of the copy / facsimile multifunction peripheral 100 is an example, and the configurations of the document reading unit 1, the document pressing cover 2, the operation unit 3, the image forming unit 4, and the like are arbitrary.

  As shown in FIG. 2, the document reading unit 1 scans an image of a document in an image reading table 10 functioning as a flat bed scanner (hereinafter referred to as “FBS”) and converts it into image data. As a reading device 11. As the reading device 11, a device generally used in a copying machine, a facsimile machine, or the like can be used. Specifically, a charge coupled image sensor using a CCD, a contact image sensor, or the like is used. be able to. Then, in order to scan the image of the document conveyed by the ADF, the reading device 11 scans the image of the document conveyed on the platen glass 12a that is the reading position of the document by the ADF from below. Further, when the reading device 11 functions as an FBS, it scans an image of a document placed on the platen glass 12b while moving in the horizontal direction below the platen glass 12b.

  The document presser cover 2 is pivotally attached to the upper surface of the reading table 10 so as to be opened and closed. When the FBS is used, the document pressing cover 2 is closed, and the document placed on the reading table 10 is pressed against the platen glass 12 b by the document pressing plate 13. Further, when the document pressing cover 2 functions as an ADF, the document before reading placed on the document placing tray 14 is separated one by one and sent to the document conveying path 15, and is a reading position by the reading device 11. The document is automatically conveyed onto the platen glass 12a. Further, the document whose image has been read is conveyed and discharged to the document discharge tray 16.

  The operation unit 3 includes various operation keys for the user to input operation instructions and paper size settings, a display panel for displaying operations and settings, and the like, as shown in FIG. , Provided in front of the document reading unit 1.

  The image forming unit 4 performs analog / digital conversion, shading processing, and the like on the image signal read by the reading device 11 and converted into an electric signal, and then in accordance with an instruction input from the operation unit 3. An image is formed on the sheet conveyed from 5 and conveyed to the sheet discharge tray 17, and is provided immediately below the document reading unit 1. The image forming unit 4 can use various recording methods known in this field such as an electrophotographic method, an ink jet recording method, and a thermal recording method as the image forming method. The image forming unit 4 discharges the sheet on which the image is recorded, and stores the discharged sheet in the sheet discharge tray 17. Further, as shown in FIG. 2, the image forming unit 4 transfers the sheet conveyed from the sheet feeding unit 5 to the sheet discharge tray 17 through various mechanisms including the photosensitive drum along the sheet conveying path 18. A plurality of conveyance rollers 19 for conveyance are provided.

  The paper feeding unit 5 includes a paper transport mechanism 20 that accommodates paper and sends a paper on which an image is recorded by the image forming unit 4 to a paper transport path 18 in accordance with a paper size instruction input from the operation unit 3. The image forming unit 3 is provided immediately below. The paper feed unit 5 is configured by stacking a plurality of paper feed units 21 in accordance with the paper size. Each paper feed unit 21 has a paper feed cassette 22 for loading and storing a large number of sheets of a predetermined size, A cassette casing 23 into which the paper feed cassette 22 can be mounted. The paper feed cassette 22 is slidably disposed with respect to the cassette casing 23, and the paper can be replenished from the opened upper surface of the paper feed cassette 22 by pulling out the paper feed cassette 22 from the cassette casing 23. As shown in FIG. 3A, the paper transport mechanism 20 transports the picked-up roller 24 that feeds the uppermost paper loaded in the paper feed cassette 22 and the fed paper toward the upper side with a nip therebetween. It comprises a conveying roller (feed roller) 25 and a press roller 26.

  The image forming unit 4 is disposed on the uppermost cassette casing 23 constituting the paper feeding unit 5. As shown in FIG. 2, the sheet conveyed by the conveying roller 25 provided in the uppermost cassette casing 23 is sent to the sheet conveying path 18 in the image forming unit 4. The plurality of cassette casings 23 constituting the sheet feeding unit 5 are provided separately. However, these cassette casings 23 may be provided integrally, and the cassette casing 23 may be integrated with the image forming unit 4 and the like. It may be provided. In the following description, as shown in FIG. 1, the upper side means the upper side of the machine base, and the lower side means the lower side of the machine base. Further, the near side means the side from which the paper feed cassette 22 is pulled out, that is, the side where the operation unit 5 is located, and the far side means the side opposite to the near side.

  As shown in FIG. 3A, the paper transport mechanism 20 feeds paper from the paper feed cassette 22 and sends it out to the paper transport path 18. On the bottom surface of the paper feed cassette 22, a support shaft (not shown) on the rear end side of the bottom plate 22a on which the sheets are stacked is supported. The bottom plate 22a is urged by a spring 22b from the lower side to the upper side (pickup roller 24 side) of the paper leading end side (paper feeding side). Further, the frame of the paper feed cassette 22 is provided with a claw 22c, and the leading edge of the uppermost sheet of paper placed on the bottom plate 22a by the claw 22c becomes the frame of the paper feed cassette 22. On the other hand, it is always kept at a predetermined height. The pickup roller 24 is formed in a substantially half-moon fan shape, and its drive shaft 24a is driven and rotated by a drive source D including an electromagnetic clutch, a gear, and the like. The pickup roller 24 is not in contact with the sheet at rest. On the other hand, the transport roller 25 is located immediately downstream in the direction in which the paper is transported from the pickup roller 24, and a drive shaft 25a formed by resin molding integrally with the transport roller 25 includes a drive source including an electromagnetic clutch, a gear, and the like. Driven and rotated by D. The peripheral surface of the transport roller 25 is covered with a material having a large friction coefficient, for example, urethane resin. The press roller 26 is provided so that its peripheral surface is pressed against the peripheral surface of the conveying roller 25 by an urging means such as a leaf spring (not shown). In FIG. 3A, only one press roller 26 is provided so that the sheet is conveyed upward by the conveying roller 25. However, as shown in FIG. 3B, a plurality of press rollers 26 may be provided, and the paper may be conveyed by making a substantially U-turn toward the left side of the drawing by the conveying roller 25. The conveyance roller 20 (see FIG. 2) located at the uppermost stream in the image forming unit 4 can be omitted.

  The electromagnetic clutch is connected in response to a paper feed instruction, and the pickup roller 24 rotates once. At this time, the arc-shaped large-diameter portion of the pickup roller 24 rotates while contacting the upper surface of the uppermost sheet placed on the bottom plate 22a, so that the sheet slides with respect to other sheets. It is paid out while waking up. As the pickup roller 24 makes one rotation, the leading edge of the sheet reaches the conveyance roller 25 disposed on the downstream side. The paper that has reached the transport roller 25 is fed into the press roller 26 and sent out toward the paper transport path 18 in the image forming unit 4.

  As shown in FIGS. 4 and 5, the paper transport mechanism 20 includes a pickup roller 24, a transport roller 25, a press roller 26, and the like disposed in the cassette casing 23. The cassette casing 23 is slidably mounted with the paper feed cassette 22, and is a casing (first shaft support member) 27 that constitutes at least a ceiling portion on the paper discharge side and a housing main portion at the back. It has. The casing 27 is integrally formed of synthetic resin, and as shown in FIGS. 4 to 6, as shown in FIGS. 4 to 6, a ceiling wall 28 which is a main part of the casing of the cassette casing 23 and a casing at the back of the cassette casing 23. And a back wall 29 constituting a main body part. The ceiling wall 28 has a space S1 in which the pickup roller 24 is accommodated on the paper discharge side, and a space S2 in which the transport roller 25 is accommodated in a gap between the ceiling wall 28 and the back wall 29 on the paper discharge side.

  The ceiling wall 28 is provided with a projection 28a as a positioning means and a mounting means as a mounting means for positioning and mounting a bracket (second shaft supporting member) 30 for pivotally supporting the pickup roller 24 above the space S1. A bent claw 28b is provided. The back wall 29 has a through-hole 29a into which a bearing 41 for rotatably supporting the drive shaft 24a of the pickup roller 24 is rotatably inserted in the back side of the space S1, and a transport roller 25 in the back side of the space S2. A through hole 29b provided with a key groove through which the bearing 42 to be supported is inserted, a through hole 29c for attaching the press roller bracket 26a rotatably supporting the press roller 26 using a fixing tool 26b such as a screw, have. Further, the rear wall 29 has a space for accommodating a drive source D including a gear, an electromagnetic clutch, a gear, and the like that are fitted to the respective ends of the drive shaft 24a of the pickup roller 24 and the drive shaft 25a of the transport roller 25. The drive shaft 24 a of the pickup roller 24 and the drive shaft 25 a of the transport roller 25 are rotationally driven by the drive source D. The bearing 42 has a key-shaped protrusion, and the protrusion is fitted into the key groove of the through hole 29b and is inserted through a through hole of a protruding piece provided integrally with the bearing 42, although not shown. The bolt is fixed to the back wall 29 by being screwed into the screw hole of the back wall 29.

  The bracket 30 is integrally formed with a thin metal plate, and as shown in FIGS. 4, 5, and 7, a first side wall 31 and a second side wall 32 that face each other with a space for housing the pickup roller 24 therebetween. The horizontal wall 33 stretched over the top ends of the first side wall 31 and the second side wall 32 is provided. And the 1st side wall 31 has the through-hole 31a by which the bearing 43 which supports the drive shaft 24a of the pick-up roller 24 rotatably is inserted. The second side wall 32 includes a U-shaped notch 32a into which a bearing 44 that rotatably supports the drive shaft 24a of the pickup roller 24 is inserted, and a through hole 32b through which the drive shaft 25a of the transport roller 25 is inserted. Have. The horizontal wall 33 has a through hole 33a inserted into a protrusion 28a provided on the ceiling wall 28 of the casing 27, and a locking surface 33b locked by the flexible claw 28a.

  In the paper transport mechanism 20 configured as described above, as shown in FIGS. 4 and 5, the drive shaft 24 a of the pickup roller 24 is a bearing on the drive source D side from the pickup roller 24, that is, on the back side from the pickup roller 24. 41 is supported by the casing 27 via the bearing 41, and is supported by the first side wall 31 of the bracket 30 via the bearing 43 on the side opposite to the drive source D side, that is, in the vicinity of the end on the near side. It is pivotally supported on the second side wall 32 of the bracket 30 via a bearing 44 slightly behind the pickup roller 24. The drive shaft 25a of the transport roller 25 is pivotally supported by the casing 27 via the bearing 42 on the drive source D side from the transport roller 25, that is, on the back side of the transport roller 25, and is opposite to the drive source D side. It is pivotally supported directly on the second side wall 32 of the bracket 30 on the side, that is, near the end on the near side.

  Since the drive shaft 25a of the conveying roller 25 is supported at both ends, even when the pressing force from the press roller 26 continues to be applied for a long period of time or when stress more than that during normal use is applied, It is possible to prevent the drive shaft 25a from being inclined. Further, the drive shaft 25 a of the transport roller 25 is directly supported by the second side wall 32 of the bracket 30 in the vicinity of the end on the near side, and the second side wall 32 is a member that also supports the drive shaft 24 a of the pickup roller 24. Therefore, since it is not necessary to add a new member, the drive shaft 25a of the transport roller 25 can be supported at both ends without substantially changing the manufacturing cost and the assembly process. Furthermore, since the drive shaft 24 of the pickup roller 24 and the drive shaft 25a of the transport roller 25 are supported on the second side wall 32 of the bracket 30, the assembly accuracy between the pick-up roller 24 and the transport roller 25 can be improved. It becomes possible to carry it better.

  Since the drive shaft 25a of the transport roller 25 is directly supported by the bracket 30 without a bearing, the drive shaft 25a is preferably formed from a resin having good sliding properties, such as polyacetal. Alternatively, grease or the like may be applied to a gap between the drive shaft 25a and the through hole 31b through which the drive shaft 25a is inserted to improve the slidability. Further, the bracket 30 may be provided with a bearing that supports the drive shaft 25 a of the transport roller 25. Note that a stepped portion formed by expanding the diameter toward the conveying roller from the portion of the driving shaft 25a of the conveying roller 23 supported by the bracket 30 may be provided. Providing such a stepped portion prevents improper rotation such as rotational shaft runout of the drive shaft 25a by the stepped portion being regulated by the outer surface of the second side wall 32 to have a predetermined inclination or greater. can do.

  In addition, the casing 23 and the bracket 30 for supporting the drive shaft 25a of the conveying roller 25 in both ends are not limited to the configuration shown in the present embodiment, and are well-known within the scope not changing the gist of the present invention. The configuration can be changed. Further, the configuration of the copy / facsimile multifunction peripheral 100 shown in the present embodiment is only one aspect provided with the paper transport mechanism according to the present invention, and the design can be changed as appropriate without departing from the gist of the present invention. Of course, for example, it can be realized as a single machine such as a copying machine or a facsimile machine.

1 is a perspective view showing a schematic configuration of a copy / facsimile multifunction peripheral 100 according to an embodiment of the present invention. FIG. 1 is a schematic sectional view showing a configuration of a copy / facsimile multifunction peripheral 100. FIG. 2A is a schematic cross-sectional view showing the paper transport mechanism 20, and FIG. 2B is a schematic cross-sectional view showing another aspect of the paper transport mechanism 20. 2 is a schematic perspective view showing a paper transport mechanism 20. FIG. FIG. 5 is a schematic cross-sectional view taken along a cutting line AA shown in FIG. 4. 3 is a schematic partial perspective view showing a casing 27. FIG. 3 is a schematic partial perspective view showing a bracket 30. FIG. FIG. 6 is a schematic cross-sectional view showing a conventional paper transport mechanism 900. FIG. 6 is a schematic perspective view showing a conventional paper transport mechanism 900. It is a schematic sectional drawing in the cutting line AA shown in FIG.

Explanation of symbols

20 Paper transport mechanism 22 Paper feed cassette 23 Cassette casing 24 Pickup roller 24a Drive shaft 25 Transport roller 25a Drive shaft 26 Press roller 27 Casing (first shaft support member)
30 Bracket (second shaft support member)
100 Copy / Facsimile MFP

Claims (3)

A pickup roller for feeding out the paper loaded in the paper cassette;
A transport roller for transporting the fed paper in a nip with a press roller;
A drive source for rotating the drive shaft of the pickup roller and the drive shaft of the transport roller;
A first shaft support member rotatably supporting the drive shaft of the pickup roller on the drive source side from the pickup roller, and the drive shaft of the transport roller on the drive source side from the transport roller;
A second shaft support section rotatably supports the drive shaft of the pickup roller on the opposite side of the drive source side from the pickup roller and the drive shaft of the carry roller on the opposite side of the drive source side from the carry roller. Material,
A paper transport mechanism comprising:   The paper transport mechanism according to claim 1, wherein the second shaft support member is attached to the first shaft support member. 3. The paper transport mechanism according to claim 1, wherein the first shaft support member is a member constituting a cassette casing on which the paper feed cassette is mounted.

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