JP2007238216A - Sheet conveying device and image forming device provided with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying device capable of accurately perform conveying regarding various sheets of different width and easily performing adjustment of pressure-contact force of the sheet of a register roller. <P>SOLUTION: The register roller 15 is divided to a plurality of parts, is fixed to a rotation shaft 40, and comprises three groups of a left roller part 15a, a central roller part 15b, and a right roller part 15c. A press roller 16 comprises press rollers 16a, 16b and 16c arranged so as to be opposed to the respective roller parts respectively, and the respective press rollers are fixed to the rotation shaft respectively and are independently mounted. The respective press rollers are pressure-contacted by the same coil spring and pressure-contact force of the central roller part 15b is strengthened by forming a diameter of the press roller 16b larger than those of other press rollers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet-like medium such as paper, a postcard, and an envelope, which can be applied to an image forming apparatus such as a copying machine, a facsimile machine, and a printer.

  In an image forming apparatus, various types of sheets such as paper, postcards, envelopes, and OHP sheets are conveyed to perform image processing. However, in order to form an image accurately on a sheet, the sheet is conveyed. It is required to accurately position the sheet. For example, if the sheet is skewed during the sheet conveying operation and image processing is performed as it is, an image is not formed in a predetermined range on the sheet, and wrinkles occur on the sheet being conveyed. It becomes a cause of various troubles.

In order to solve such problems, in the sheet conveying apparatus of the image forming apparatus, a registration roller is disposed, and the leading edge of the sheet is once brought into contact with the registration roller to correct the skew of the sheet so that the sheet is conveyed accurately. I have to. Further, in Patent Document 1, the roll body of the driven roller pressed against the roll body of the driving roller is fixed by an individual shaft, and the roll body at the center of the driven roller is more elastically biased than the roll bodies at the left and right ends. The point is described. Further, Patent Document 2 describes that the driven roller roll body pressed against the drive roller roll body is fixed by individual shafts, and the roll bodies at the left and right end portions are inclined with respect to the transport direction. ing. Further, Patent Document 3 describes that the registration roller is configured by five individual registration rollers, and the registration rollers are configured by individual registration rollers corresponding to the individual registration rollers, respectively. Further, in Patent Document 4, a plurality of driven rollers are supported so as to be able to contact and separate independently from each other, and each driven roller contacts the driving rollers in a predetermined order and all the driven rollers. It is described that the mode is switched to the conveyance mode in which the is in contact with the driving roller.
JP 2003-160256 A JP 2003-160255 A JP 2004-263343 A Japanese Patent Laid-Open No. 2002-226088

  In a configuration in which a plurality of press rollers are fixed to a single shaft and pressed against a registration roller as in a conventional sheet conveying apparatus, the pressure contact force is not uniform between the press rollers, and unevenness is likely to occur. Therefore, as described in Patent Document 1, it is conceivable that each press roller is pressed against the registration roller independently, but it is possible to convey various sheets having different widths without causing any trouble. Necessary.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet conveying apparatus that can accurately convey various sheets having different widths and can easily adjust the pressure contact force of a sheet of a registration roller. Is.

  The sheet conveying device according to the present invention is a resist roller in which a left roller portion, a central roller portion, and a right roller portion are arranged and fixed in the axial direction on a single shaft shaft, and each roller portion is arranged to face each other independently And three press rollers pressed against the respective roller portions by the same urging means, and the central roller is formed in a shape different from that of the other press rollers. The pressure contact force to the portion is set to be larger than that of the other roller portions. Furthermore, the diameter of the press roller disposed opposite to the central roller portion is formed larger than the diameter of the other press rollers. Furthermore, the axial length of the press roller disposed opposite to the central roller portion is shorter than the lengths of the other press rollers. Furthermore, a gap between the left and right roller portions is provided so that a narrow sheet can be conveyed only by the central roller portion.

  An image forming apparatus according to the present invention includes the above sheet conveying device.

  By having the configuration as described above, the registration roller is divided into three roller portions, and the press rollers are arranged so as to face each roller portion independently, so that the pressure contact force at each roller portion can be easily adjusted. In addition, it is possible to easily change the pressure contact force to each roller portion by urging each press roller with the same urging means and changing the shape of the press roller.

  That is, changing the urging force applied to each press roller to change the pressing force to each roller part requires changing the urging means, and it is difficult to fine-tune the urging force, Changing the shape of the press roller using the same urging means for each press roller is only necessary to replace the press roller, and it is also easy to finely adjust the pressure contact force by slightly changing the shape. It can also be done.

  And by making the shape of the press roller arranged opposite to the central roller portion different from the shape of other press rollers, the pressure contact force to the central roller portion is larger than the other roller portions, so that various types of sheets can be obtained. It becomes possible to convey accurately.

  That is, a wide sheet such as A4 size is difficult to skew because the left and right roller portions sandwich both sides of the sheet and the central roller portion conveys the central portion of the sheet with a strong pressing force. In addition, in the case of a narrow sheet such as a postcard, if the sheet is conveyed only by the central roller portion, it is not skewed.

  By providing such a configuration in the registration roller that corrects the skew of the sheet, accurate sheet conveyance can be realized.

  In addition, by forming the diameter of the press roller disposed opposite to the central roller portion to be larger than the diameter of the other press rollers, the central roller portion can be pressed even if it is urged by the same urging means. The power can be increased.

  In addition, by forming the axial length of the press roller disposed opposite to the central roller portion to be shorter than the length of the other press rollers, the contact area with the central roller portion is reduced and the pressing force is applied by the same urging means. Even if it is urged, the pressure contact force of the central roller portion is increased.

  In addition, by separating the left and right roller portions so that a narrow sheet can be conveyed only by the central roller portion, it becomes possible to accurately convey a narrow sheet without skewing. . Since the press roller is driven to rotate, there is no concern that the difference in the diameter of the press roller will cause a problem in paper conveyance.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic sectional view of an entire image forming apparatus including an embodiment according to the present invention. The image forming apparatus 1 includes a recording unit 2 and a paper feeding unit 3.

  In the paper feed unit 3, paper feed cassettes 10a and 10b are arranged in two upper and lower stages, and a plurality of standard sheets, which are wide sheets, are stacked on a flapper 11a in the paper feed cassette 10a. A pickup roller 12a is disposed at the right end portion of the paper feed cassette 10a, and is urged upward by a spring member (not shown) so that the upper surface of the paper on which the flapper 11a is stacked is pressed against the pickup roller 12a. . When the pickup roller 12a is rotationally driven in this state, the sheets are fed one by one to the sheet conveyance path by the frictional force. In the paper feed cassette 10b as well, the paper loaded on the flapper 11b is fed by the pickup roller 12b in the same manner as the paper feed cassette 10a.

  The fed paper is first conveyed to the recording unit 2 by the feed roller 13 and the press roller 14. The conveyed sheet is nipped between the registration roller 15 and the press roller 16 and conveyed at a constant conveyance speed. The recording unit 2 includes a developing unit 17, a memory removal brush 18, a charging roller 19, a photosensitive drum 20, a transfer roller 21, an exposure head 22, and a fixing roller 23 for recording on paper.

  When recording on a sheet, the surface of the photosensitive drum 20 is uniformly charged by the charging roller 19, and the charged surface of the photosensitive drum 20 is exposed by the exposure head 22 in accordance with the image recording signal. An electrostatic latent image is formed. Next, toner is supplied to the surface of the photosensitive drum 20 by the developing unit 17 to be transferred to an electrostatic latent image to be visualized, and the toner image visualized by the transfer roller 21 is transferred onto a sheet. The transferred toner image is heated and pressed by the fixing roller 23 and the press roller 24 to be fixed on the paper.

  In this way, a series of processes such as charging, exposure, development, transfer, and fixing to the photosensitive drum 20 are performed, and image forming processing is performed. The toner remaining on the surface of the photosensitive drum 20 after transfer is weakened by the memory removing brush 18 and dispersed on the surface of the photosensitive drum 20 and collected by the developing unit 17.

  In the developing device 17, an opening is formed on the photosensitive drum 20 side of the main body frame 30, and a developing roller 31 is pivotally supported. A supply roller 32 is pivotally supported adjacent to the developing roller 31, and a supply chamber 33 communicates with the supply roller 32. Toner is stored in the replenishing chamber 33, and the toner is agitated by the agitating member 34 provided in the replenishing chamber 33. At the upper part of the replenishing chamber 33, a lid body 35 is tightly fixed to the body frame 30.

  The toner stirred in the replenishing chamber 33 is transferred toward the supply roller 32 and conveyed toward the developing roller 31 by the rotation of the supply roller 32. The toner transferred from the supply roller 32 to the developing roller 31 is leveled to a predetermined layer thickness on the surface of the developing roller 31 by a blade (not shown) and supplied to the photosensitive drum 20.

  The paper fixed by the fixing roller 23 is nipped between the paper discharge roller 25 and the press roller 26 and carried out. Also, a manual paper feed mechanism is provided on the side surface of the apparatus main body, and a narrow sheet such as a postcard or an envelope inserted into the paper feed port is sandwiched between the feed roller 27 and the press roller 28 to be inside the apparatus. And is sandwiched between the registration roller 15 and the press roller 16 described above, and the same image forming process as described above is performed.

  FIG. 2 is a view of the registration roller 15 and the press roller 16 as viewed from the sheet conveyance direction, and FIG. 3 is a cross-sectional view taken along line AA of FIG. The registration roller 15 is divided into a plurality of parts and is fixed to the rotating shaft 40, and includes three groups of a left roller part 15a, a central roller part 15b, and a right roller part 15c. The rotating shaft 40 is rotatably supported on both ends of shaft supporting portions 41 and 42 projecting from a body frame (not shown), and a drive gear 43 is fixed to the right end portion. Then, the drive gear 43 is rotationally driven by a drive transmission mechanism (not shown) so that the registration roller 15 is rotated.

  The press roller 16 includes press rollers 16a, 16b, and 16c arranged to face the left roller portion 15a, the center roller portion 15b, and the right roller portion 15c, respectively. The press rollers 16a, 16b, and 16c have rotating shafts 50a and 50b, respectively. And 50c and are attached independently. The rotary shaft 50a is rotatably mounted with pivot support members 51a and 52a on both sides, and the pivot support members 51a and 52a are provided with engaging portions formed by cutting out on both sides.

  Then, the engagement protrusions formed at the distal ends of the pair of support portions 53a and 54a suspended from the upper frame are engaged with the engagement portions of the shaft support members 51a and 52a so that only the vertical movement is possible. The shaft support member 51a is always biased downward by the coil spring 55a disposed between the support portions 53a, and the shaft support member 52a is always biased downward by the coil spring 56a disposed between the support portions 54a. It has come to be.

  Therefore, the press roller 16a is held in pressure contact with the left roller portion 15a by the urging force of the coil springs 55a and 56a. Further, the rotary shaft 50a is moved upward against the biasing force of the coil springs 55a and 56a to disengage the shaft support members 51a and 52a from the engagement of the support portions 53a and 54a. The press roller 16a can be easily replaced.

  The press roller 16b is pressed against the central roller portion 15b by the biasing force of the coil springs 55b and 56b with the same configuration as the press roller 16a, and the press roller 16c is pressed against the right roller portion 15c by the biasing force of the coil springs 55c and 56c. Here, the same coil spring is used for the coil springs 55a to 55c and 56a to 56c.

  In this example, the diameters of the press rollers 16a and 16c are the same, the diameter of the press roller 16b is formed larger than the diameter of the press rollers 16a and 16c, and the rotation shaft 50b is increased by the larger diameter of the press roller 16b. And 50c. Therefore, the coil springs 55b and 56b are compressed more than the other coil springs, and a stronger urging force is applied than the other coil springs, and the press roller 16b causes the central roller portion 15b to move from the press rollers 16a and 16c. Is also pressed by a strong pressure.

  Accordingly, the pressure contact force of the central roller portion 15b is stronger than the left and right roller portions 15a and 15c, and the central portion of the sheet is strongly held and conveyed when the sheet is conveyed by the registration roller 15. For this reason, it is possible to perform an accurate transport operation while suppressing the skew of the sheet.

  FIG. 4 shows a modification of the press roller 16b. In this example, the lengths of the press rollers 16a and 16c in the axial direction are the same, and the length of the press roller 16b ′ in the axial direction is the same as that of the press rollers 16a and 16c. It is shorter than the length. The central roller portion 15b is set to the same length as the axial length of the press roller 16b '. Therefore, the area where the press roller 16b contacts the central roller portion 15b is smaller than the contact area of the other press rollers. Therefore, even when the same coil spring is urged with the same urging force, the press contact force of the press roller 16b is stronger than the other press rollers because the contact area is small. Accordingly, as in the case of FIG. 2, the central portion of the sheet is strongly held during the sheet conveyance, and an accurate conveyance operation can be performed.

  As described above, the pressing force applied to the central roller portion can be increased by making the shape of the press roller disposed opposite to the central roller portion of the registration roller different from that of the other press rollers. Then, the press contact force can be appropriately adjusted by replacing the press roller, and the optimum press contact force can be easily set using the same coil spring.

  FIG. 5 is a schematic perspective view showing a conveyance path when conveying a sheet R1 such as a narrow postcard or envelope and a sheet R2 such as a wide standard sheet. As shown in FIG. 5, the sheet conveyance path of the sheet R1 is set so as to be held only by the center roller portion 15b and the press roller 16b, and the interval between the left and right roller portions 16a and 16c is larger than the width of the sheet R1. It is set widely and is not sandwiched between the left and right roller portions 16a and 16c. Accordingly, since the left and right roller portions 16a or 16c having a pressure contact force different from that of the central roller portion 15b do not act on the sheet R1 during conveyance, it is possible to accurately convey even the narrow sheet R1. Further, in the case of the sheet R2, since both sides of the sheet R2 are sandwiched by the left and right roller portions 15a and 15c together with the central roller portion 15b, the sheet R2 is widely transported by the strong pressure contact force of the central roller portion 15b while being sandwiched between the left and right sides. Even in the case of the sheet R2, an accurate conveying operation can be performed without skew.

1 is a schematic cross-sectional view of an entire image forming apparatus including an embodiment according to the present invention. It is the figure which looked at the registration roller and the press roller from the paper conveyance direction. It is AA sectional drawing of FIG. It is a figure which shows the modification of FIG. It is a schematic perspective view which shows a sheet conveyance path | route.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Recording part 3 Paper feeding part
15 Registration roller
15a Left roller
15b Center roller section
15c Right roller part
16 Press roller
40 axis of rotation
50 axis of rotation
55 Coil spring
56 Coil spring

Claims (5)

  A registration roller in which a left roller portion, a central roller portion, and a right roller portion are arranged and fixed in the axial direction on one shaft shaft, and each roller portion are arranged to face each other independently, and the same biasing means Three press rollers pressed against each roller portion, and the press roller disposed opposite to the central roller portion is formed in a different shape from the other press rollers so that the pressure contact force to the central roller portion is the other roller The sheet conveying apparatus is set so as to be larger than the section.   The sheet conveying apparatus according to claim 1, wherein a diameter of a press roller disposed to face the central roller portion is formed larger than a diameter of another press roller.   The sheet conveying apparatus according to claim 1, wherein a length of an axial direction of a press roller disposed to face the central roller portion is shorter than a length of another press roller.   The sheet conveying apparatus according to any one of claims 1 to 3, wherein a space between the left and right roller portions is provided so that a narrow sheet can be conveyed only by the central roller portion.   An image forming apparatus comprising the sheet conveying device according to claim 1.

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