JP2007309436A - Resin gear, developing machine with it, photoconductor drum unit and image forming device or image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin gear capable of improving dimensional accuracy in the case that a reinforcing rib is formed. <P>SOLUTION: In the gear 1, an attachment hole 3 for mounting a rotation shaft is formed at a center part and an outer circumference edge part 2 is provided coaxially with the attachment hole 3. A plurality of tooth profiles 4 are formed in an outer circumference face of the outer circumference edge part 2 at even intervals. A projection edge 3a is formed at a circumference edge part of the attachment hole 3 and a plurality of rib parts 5 radially extended from an outer circumference face of the projection edge 3a are connected to an inner circumference face of the outer circumference edge part 2 and integrally formed. Connection parts of the rib parts 5 to the outer circumference edge part 2 are set corresponding to positions between tooth profiles 4 and prevent a thick part from continuously forming from the tooth profiles 4 to the rib parts 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin gear that can be applied to a drive transmission mechanism of a copying machine, a facsimile machine, a printer, and the like, and a developing device, a photosensitive drum unit, an image forming apparatus, or an image reading apparatus including the same.

  In drive transmission mechanisms of various apparatuses including a drive transmission mechanism such as a copying machine, a facsimile machine, and a printer, a driving force from a driving source such as a motor is transmitted using a gear. Such a drive transmission gear is manufactured by processing from a metal material, but a resin gear is used from the viewpoint of cost and weight reduction.

For example, Patent Document 1 describes that a plurality of ribs are arranged at the base portion of a tooth in order to secure rigidity by arranging a plurality of ribs radially with a web formed in a disk shape. Patent Document 2 describes that a twisted tooth is formed on the outer peripheral side of the annular portion, and a plurality of reinforcing ribs are radially formed inside the annular portion. Patent Document 3 includes a boss formed at the center, a rim formed concentrically with the boss in the outer circumferential direction, and a thin web integrally connected between the boss and the rim. It is described that ribs are integrally formed radially at positions corresponding to all of the teeth.
Japanese Patent Laid-Open No. 10-196767 JP-A-10-196766 JP 2003-139219 A

  In the conventional resin gear, as described in the above-mentioned prior document, a plurality of reinforcing ribs formed radially are provided inside. However, in such a resin gear, as shown in FIG. Reinforcing ribs R are connected and integrally formed at positions corresponding to the tooth base of T (portions surrounded by dotted circles). In such a shape, a portion having a large resin thickness is continuously formed from the tooth profile T to the reinforcing rib R. Therefore, when resin molding is performed, the shrinkage rate increases as the thickness increases when the resin is cooled and solidified. As a result, the entire gear shrinks unevenly and cannot be finished to the designed dimensions.

  In particular, gears used in drive transmission mechanisms such as copying machines, facsimile machines, printers, and the like do not use gears with high dimensional accuracy, resulting in errors in paper transport operations and image formation processing, which directly leads to degradation of image quality.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a resin gear that can increase the dimensional accuracy when a reinforcing rib is formed, and a developing device, a photosensitive drum unit, an image forming apparatus, or an image reading apparatus having the resin gear. It is what.

  The resin gear according to the present invention includes an outer peripheral edge portion having a plurality of tooth forms formed at equal intervals on the outer peripheral surface, an attachment hole drilled in the center portion, and a radial extension from the peripheral edge portion of the attachment hole. A plurality of ribs connected to the inner peripheral surface of the outer peripheral edge part, and a resin gear integrally formed of a resin material, wherein the rib part is located at a position corresponding to between the tooth form and the tooth form. It is connected to the inner peripheral surface of the outer peripheral edge. Furthermore, the rib portion is set to a thickness substantially the same as the thickness of the tooth root of the tooth profile.

  The developing device according to the present invention includes the resin gear.

  A photosensitive drum unit according to the present invention includes the resin gear.

  An image forming apparatus according to the present invention includes the resin gear.

  An image reading apparatus according to the present invention includes the resin gear.

  Since the resin gear according to the present invention has the above-described configuration, the rib portion is connected to the inner peripheral surface of the outer peripheral edge portion at a position corresponding to between the tooth profile and the tooth profile. A thick portion with a continuous tooth profile is not formed, the occurrence of a shrinkage difference during resin molding at the connecting portion can be suppressed, and the dimensional accuracy of the entire gear can be increased.

  In addition, if the thickness of the rib part is set to be substantially the same as the thickness of the tooth root of the tooth profile, the rib part also contracts at substantially the same contraction ratio as that during resin molding of the tooth profile. The influence of the contraction on the dimensional accuracy of the tooth profile can be suppressed.

  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 front view of a resin gear according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG. The gear 1 is formed with an attachment hole 3 for mounting the rotation shaft at the center, and has an outer peripheral edge 2 formed concentrically with the attachment hole 3. A plurality of tooth profiles 4 are formed at equal intervals on the outer peripheral surface of the outer peripheral edge 2.

  A protruding edge 3a is formed on the peripheral edge of the mounting hole 3, and a plurality of ribs 5 extending radially from the outer peripheral surface of the protruding edge 3a are connected to the inner peripheral surface of the outer peripheral edge 2 to be integrally formed. Has been. The connecting portion of the rib portion 5 to the outer peripheral edge portion 2 is set at a position corresponding to between the tooth profiles 4 so that a thick portion is not continuously formed from the tooth shape 4 to the rib portion 5. Moreover, between the rib parts 5, the meat stealing part 6 formed thinly is formed, and weight reduction is achieved. And the rigidity of the gear 1 whole can be ensured, reducing in weight by forming the some radial rib part 5. As shown in FIG.

  The outer peripheral width d of the outer peripheral edge portion 2 is set to be the same as the tooth thickness d of the tooth root of the tooth profile 4, and similarly the tooth of the tooth profile 4 with respect to the width d of the rib portion 5 and the width d of the protruding edge 3 a. It is set to be the same as the original tooth thickness d. In addition, by setting the thickness of the meat stealing portion 6 to the same thickness as the tooth thickness d, the thickness of the resin of each part of the entire gear 1 becomes uniform, and the contraction difference of the entire gear during resin molding is suppressed. Thus, the dimensional accuracy of the entire gear can be further increased.

  When the gear 1 is manufactured by a resin molding process, if two molds are brought into close contact with each other, the molten resin is poured into the mold, and the molten resin is poured into the mold and cooled to solidify the molded resin. In the case of the gear 1, the thickness of the resin is almost constant at each part, so that the whole contracts uniformly, and it is easy to finish the dimensional accuracy as designed. Become.

  FIG. 4 shows a schematic view of the entire image forming apparatus provided with a resin gear according to an embodiment of the present invention. A document reading unit 100 that conveys a document and reads the document is disposed in the upper part of the image forming apparatus, and a recording unit 200 that records an image, a sheet transport unit 300 that transports a sheet on which an image is recorded, and a paper feed unit 400 is arranged.

  The document reading unit 100 includes a cover unit 10 provided with a document conveying device (ADF) and a reading body unit 12 provided with a scanner 11. On the upper surface of the reading main body 12, a platen glass 13 is disposed at a portion for reading the conveyed document, and a placement bed 14 made of a transparent glass material is disposed at a portion for placing and reading the document or book. Yes. When reading a transported document, the scanner 11 is stopped at a position facing the platen glass 13 to perform a reading operation. When reading a document placed on the mounting bed 14, the scanner 11 reads a document or the like. Are scanned to perform a reading operation.

  A document retainer 15 is attached to the surface of the cover portion 10 facing the placement bed 14, and a document tray 16 on which a plurality of documents are placed is provided above the document retainer 15. A document placed on the document tray 16 is carried into the ADF by a pickup roller 17 and a separation roller 18, conveyed to a reading position facing the platen glass 13 by a feed roller 19, read by a scan 11, and read by a discharge roller 20. It is discharged to the document discharge tray 21.

  The recording unit 200 includes a developing device 22, a charging brush 23, a photosensitive drum 24, a transfer roller 25, an exposure head 26, a memory removal brush 27, and a fixing roller 28 for recording on the paper conveyed by the paper conveyance unit 300. Is provided. First, the surface of the photosensitive drum 24 is uniformly charged by the charging brush 23, and the electrostatic latent image is formed by exposing the charged surface of the photosensitive drum 24 according to the image recording signal by the exposure head 26. . Next, the toner in the developing device 22 is transferred to the electrostatic latent image formed on the photosensitive drum 24 by the supply roller and the developing roller to be visualized, and formed on the surface of the photosensitive drum 24 by the transfer roller 25. Transfer the toner image onto the paper. The transferred toner image is heated and pressed by the fixing roller 28 and fixed on the paper.

  In this way, a series of processes such as charging on the photoreceptor, exposure, development, transfer to paper and fixing are performed, and an image is formed on the paper. The toner remaining on the surface of the photosensitive drum 24 after the transfer is weakened in adhesion by a memory removal brush (ERS brush) 27 and dispersed on the surface of the photosensitive drum 10. The residual toner is collected on the developing roller of the developing device 22.

  A plurality of sheets are stacked and set in the sheet feed cassette 5 in the sheet feed unit 400, and are fed one by one by the sheet feed roller 29 to the sheet transport unit 300. The fed paper is conveyed by the feed roller 30 and is sandwiched between the feed rollers 31 and 32. Then, the sheet is conveyed to the recording unit 200 by the feed roller 31 to form an image, and the sheet subjected to the image forming process is sandwiched between the fixing roller 28 and the press roller 33 to perform the fixing process, and then is discharged by the discharge roller 34. It is carried out to the paper discharge tray 35.

  The developing roller and the supply roller of the developing device 22 have a roller shaft supported by the frame of the developing device 22, and a driving force from a driving motor (not shown) is transmitted by a gear fixed to the end of the roller shaft. It starts to rotate. Regarding the developing roller and the supply roller, the above-described resin gear is used for rotational driving of each roller shaft. By using the resin gear according to the present invention, it is possible to perform accurate rotation control with high dimensional accuracy and contribute to the weight reduction of the developing device.

  The photosensitive drum 24, the exposure head 26, and the memory removal brush 27 are unitized and integrated as a photosensitive drum unit. The photosensitive drum 24 has a drum shaft pivotally supported on the frame of the unit, and rotates when a driving force from a driving motor (not shown) is transmitted by a gear fixed to the end of the drum shaft. As for the photosensitive drum 24, the above-described resin gear is used for rotational driving. By using the resin gear according to the present invention, it is possible to perform accurate rotation control with high dimensional accuracy and contribute to reducing the weight of the photosensitive drum unit.

  In addition, the feed rollers 30 and 31 and the paper discharge roller 34 that perform the paper transport operation have a roller shaft supported by the frame of the apparatus main body, and a drive motor (not shown) by a gear fixed to the end of each roller shaft. The driving force from is transmitted to rotate. With respect to these rollers, the above-described resin gear is used for rotational driving. By using the resin gear according to the present invention, it is possible to perform accurate rotation control with high dimensional accuracy and contribute to the weight reduction of the image forming apparatus.

  FIG. 5 is a perspective view showing an example in which the resin gear according to the present invention is applied to the feed roller 30. In the feed roller 30, a plurality of roller portions 30 b are fixed to a roller shaft 30 a, and both end portions of the roller shaft 30 a are attached to a frame via a shaft support member 40. The resin gear 1 is fixed by fitting the mounting hole 3 to one end of the roller shaft 30a.

  In the document reading unit 100, the ADF feed roller 19 has a roller shaft pivotally supported on the frame of the document reading unit 100, and a driving force from a driving motor (not shown) by a gear fixed to the end of the roller shaft. Is transmitted and begins to rotate. With respect to the feed roller 19, the above-described resin gear is used for rotational driving. By using the resin gear according to the present invention, it is possible to perform accurate rotation control with high dimensional accuracy and contribute to the weight reduction of the document reading unit.

  In the example described above, a spur gear is described as an example, but the present invention can be applied to a resin gear other than a spur gear.

It is a front view regarding the resin-made gearwheel which is embodiment which concerns on this invention. It is AA sectional drawing of FIG. It is a front view regarding the conventional gearwheel. 1 is a schematic view of an entire image forming apparatus including a resin gear according to an embodiment of the present invention. It is a perspective view regarding the feed roller to which resin gears are applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin gear 2 Outer peripheral edge part 3 Mounting hole 4 Tooth profile 5 Rib part 6 Meat stealing part
100 Document reader
200 Recording section
300 Paper transport section
400 Feeder

Claims (6)

  An outer peripheral edge with a plurality of teeth formed at equal intervals on the outer peripheral surface, a mounting hole drilled in the center, and a radial extension from the peripheral edge of the mounting hole and connected to the inner peripheral surface of the outer peripheral edge A resin gear integrally formed of a resin material, wherein the rib portion is connected to the inner peripheral surface of the outer peripheral edge at a position corresponding to the tooth profile. A resin gear characterized by being made.   2. The resin gear according to claim 1, wherein the rib portion is set to have substantially the same thickness as a tooth root of the tooth profile.   A developing device comprising the resin gear according to claim 1.   A photosensitive drum unit comprising the resin gear according to claim 1.   An image forming apparatus comprising the resin gear according to claim 1.   An image reading apparatus comprising the resin gear according to claim 1.

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