JP2007155891A - Driving transmitting device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a high-quality image by stably driving a transfer belt by enhancing the rigidity of a gear for transmitting driving from a driving motor to the transfer belt and a photoreceptor drum so as to prevent the deformation of the gear without increasing cost highly. <P>SOLUTION: A transfer belt gear mechanism 66 for transmitting the driving of the driving motor 61 to the transfer belt 21 and a belt gear mechanism 72 having a drive gear 73 for transmitting the driving of the driving motor 61 to the photoreceptor drum 10 are integrally formed. A collar 80 having a first ring 80b and a second ring 80c is integrally formed. The collar 80 is lightly press-fit between the bearing part 66b and the wall part 66c of the transfer belt gear mechanism 66. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to a drive transmission device and an image forming apparatus for transmitting driving from the same driving source to a photosensitive member and a transfer belt.

  In an image forming apparatus that obtains a color image by an electrophotographic method, such as a color copying machine or a color printer apparatus, there is an apparatus that uses an endless transfer belt to transfer a toner image of each color formed on a photosensitive drum. . As a device using a transfer belt, a sheet paper is interposed between the photosensitive drum and a device for directly transferring the toner image on the photosensitive drum onto the sheet paper, or the toner image on the photosensitive drum is transferred to the transfer belt. There is an apparatus for performing secondary transfer onto a sheet after primary transfer. In order to reduce the size of the image forming apparatus using the transfer belt or reduce the cost, in recent years, there is an apparatus that drives the transfer belt together with the photosensitive drum using the same drive motor.

  Further, in such an image forming apparatus, the speed of the photosensitive drum is set to be slightly faster than the speed of the transfer belt in order to prevent color misregistration of the color image. On the other hand, at the time of image formation, the transfer belt and the photosensitive drum are attracted by a strong force due to electrostatic attraction. Therefore, at the time of image formation, the driving force transmitted from the driving motor to the transfer belt via the gear and the force from the transfer belt that tries to rotate under the control of the photosensitive drum (the transmission speed from the gear side). Force to try to rotate faster). Since two forces, the driving force from the driving motor and the force to rotate fast from the transfer belt side, are applied, the gear connected to the transfer belt may be deformed by a high load and drive transmission may be disturbed.

For this reason, conventionally, an apparatus for increasing the rigidity of the gear has been disclosed in order to prevent the deformation of the gear. (For example, refer to Patent Document 1 and Patent Document 2.)
JP 2003-336696 A (page 4, FIGS. 4, 5) Japanese Patent Laying-Open No. 2002-82574 (6th and 7th pages, FIGS. 7 and 8) (Patent Document 1) includes a rib on a branch gear.

  (Patent Document 2) covers a first component formed with a material having high rigidity and a second component formed with a tooth portion with a material capable of realizing high accuracy.

  However, in Patent Document 1, there is a difference in the rigidity of the gear between where the rib is present and where the rib is not. The speed fluctuation for each rib pitch due to the difference in rigidity appears as jitter on the image, causing streaks in the image. Further, the gear meshing accuracy may be reduced by sinking of the rib portion.

  On the other hand (Patent Document 2), the use of a highly rigid material increases the price. In addition, since the gear is not integrally formed and is composed of two components, the tooth portion is not driven by the shaft via the first highly rigid component portion. May occur.

  Therefore, the present invention solves the above-mentioned problems, and forms a high-quality image by preventing the speed fluctuation of the transfer belt caused by the deformation of the gear connected to the transfer belt, even though a high load is applied. An object of the present invention is to provide a drive transmission device and an image forming apparatus that are possible and that do not significantly increase costs.

  According to the present invention, as means for solving the above-mentioned problems, a first gear mechanism that transmits driving to the first driving unit and a second gear mechanism that transmits driving to the second driving unit are integrally formed. In the drive transmission device having a gear body, the first gear mechanism includes a bearing portion through which a shaft is inserted, a wall portion that is radially connected to the bearing portion, and a radial portion that is connected to the wall portion. And a reinforcing member that is lightly press-fitted between the bearing portion and the wall portion of the first gear mechanism.

  According to the present invention, the rigidity of the gear can be evenly increased by lightly press-fitting the reinforcing member between the bearing portion and the wall portion of the gear mechanism, and the transfer of the gear mechanism can be prevented by preventing deformation of the gear mechanism. High-quality images can be obtained by preventing belt speed fluctuations. Moreover, it is easy to manufacture and does not significantly increase the cost.

  Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram showing a color printer apparatus 1 which is an image forming apparatus according to an embodiment of the present invention. The color printer apparatus 1 includes a paper feeding device 3 that supplies the sheet paper P in the direction of the printer 2. The paper feeding device 3 takes out the sheet paper P from the paper feeding cassettes 3a and 3b, and feeds the sheet paper P in the direction of the registration roller 27 along the conveyance path 3c. A scanner 4 for reading an original image is provided on the upper surface of the color printer apparatus 1.

  A toner image forming unit 11 that is an image forming member that forms toner images of a plurality of colors on the photoconductive drum 10 is provided around the photoconductive drum 10 that is an image carrier and a second driving unit of the printer 2. . The toner image forming unit 11 is arranged on the photosensitive drum 10 charged on the basis of image data from the charging device 12 and the scanner 4 that uniformly charges the photosensitive drum 10 sequentially in accordance with the rotation of the photosensitive drum 10 in the arrow s direction. A revolver type color developing device 20 equipped with a laser exposure device 13 for forming an electrostatic latent image, a black developing device 14, a yellow (Y) developing device 16, a magenta (M) developing device 17, and a cyan (C) developing device 18. have.

  Further, a transfer belt device 40 is disposed opposite to the transfer position around the photosensitive drum 10. The transfer belt device 40 has a transfer belt 21. As shown in FIG. 2, the transfer belt 21 is stretched by a belt driving roller 32, a driven roller 31, and a tension roller 33, which are first driving units, and is rotated in the direction of an arrow v. The position of the transfer belt 21 in contact with the photosensitive drum 10 is supported by a primary transfer roller 37 and an auxiliary roller 38 that apply a primary transfer bias. Further, a secondary transfer roller 28 to which a secondary transfer bias is applied is opposed to a secondary transfer position supported by the driven roller 3 1 of the transfer belt 21.

  The photosensitive drum 10 rotates at a speed that is slightly faster than the rotation speed of the transfer belt 21. The transfer belt 21 tries to rotate under the control of the photosensitive drum 10. This prevents color misregistration of the toner image that is primarily transferred from the photosensitive drum 10 to the transfer belt 21. A belt cleaning device 36 is provided around the transfer belt 21 after passing through the secondary transfer position. A cleaner device 22 is disposed downstream of the transfer belt 21 around the photosensitive drum 11.

  Further, the printer 2 includes a secondary transfer roller 28 that secondarily transfers a plurality of color toner images superimposed on the transfer belt 21 onto the sheet paper P, a fixing device 30 that fixes the toner image on the sheet paper P, and a sheet after fixing. A paper discharge roller 24 a that discharges the paper P to the paper discharge unit 24 is provided. Further, the printer 2 has a reverse conveyance path 25 for reversing the sheet paper P when double-sided images are formed.

  As shown in FIG. 3, on the rear side of the printer 2, a drive motor 61 is provided as a drive source that rotationally drives the photosensitive drum 10 and the transfer belt 21. As the drive motor 61, a servo motor with little rotational vibration, a stepping motor with a small step, a DC brushless motor, or the like is used.

  The driving motor 61 is driven by a belt driving shaft 65 that is a driving shaft for driving the belt driving roller 32 and a photosensitive shaft via a link mechanism 60 having a reduction gear mechanism 64, a belt gear mechanism 72 that is a gear body, and a drum gear 74. It is transmitted to a drum drive shaft 75 for driving the body drum 10. The belt drive shaft 65 is connected to the roller support shaft 32 a of the belt drive roller 32 by a belt coupling 67. The drum drive shaft 75 is connected to the drum shaft 77 by a drum coupling 76.

A flywheel 78 for stably rotating the photosensitive drum 10 is provided on the rear side of the drum drive shaft 75.

  The output shaft 62 of the drive motor 61 also serves as the motor drive gear 63. The reduction gear mechanism 64 includes a first stage gear 70 and a second stage gear 71. The belt gear mechanism 72 includes a transfer belt gear mechanism 66 that is a first gear mechanism and a drive gear 73 that is a second gear mechanism. The motor drive gear 63 and the first stage gear 70 of the reduction gear mechanism 64 mesh with each other. The second gear 71 of the reduction gear mechanism 64 meshes with the transfer belt gear portion 66a that is the first gear portion of the transfer belt gear mechanism 66. The drive gear 73 of the belt gear mechanism 72 meshes directly with the drum gear 74.

  The reduction gear mechanism 64, the belt gear mechanism 72, and the drum gear 74 are helical gears or helical gears formed by resin molding such as injection molding. Gear materials include polyacetal resins with excellent dimensional stability, self-lubricating properties and moldability, synthetic resins such as polyimide and polycarbonate with low thermal expansion, and resins with improved strength and rigidity by filling polycarbonate with glass-reinforced fibers. Alternatively, a resin in which a self-lubricating property is improved by blending a fluororesin with polycarbonate can be used.

  Next, the belt gear mechanism 72 shown in FIGS. 4-A and 4-B, which is formed by integrally forming a polyacetal resin by injection molding, will be described in detail. At the time of image formation, the driving force from the driving motor 61 is transmitted to the transfer belt gear mechanism 66 of the belt gear mechanism 72, while the belt driving shaft 65 rotates at a high speed from the transfer belt 21 that electrostatically attracts the photosensitive drum 10. The power to try works. Since two forces of a driving force from the driving motor 61 and a force from the transfer belt 21 are applied, a high load is applied between the bearing portion 66b and the transfer belt gear portion 66a of the transfer belt gear mechanism 66.

  In order to prevent the transfer belt gear mechanism 66 from being deformed by the high load, a collar 80 which is a reinforcing member and has a disk shape is attached to the transfer belt gear mechanism 66 to increase rigidity. At the center of the transfer belt gear mechanism 66, a bearing portion 66b that fits with the belt drive shaft 65 is formed. A wall portion 66c coaxial with the belt drive shaft 65 is formed outside the bearing portion 66b. The wall portion 66c is connected to the bearing portion 66b in the radial direction by the first connecting portion 66d. The transfer belt gear portion 66a is connected to the wall portion 66c in the radial direction by the second connecting portion 66e. The center of the second connecting portion 66e in the thickness direction is located at the center of the gear width of the transfer belt gear portion 66a.

  The collar 80 shown in FIGS. 5-A and 5-B is integrally formed by injection molding using the same polyacetal resin as the material of the belt gear mechanism 72. An opening 80 a is formed at the center of the collar 80 so that the collar 80 does not touch the belt drive shaft 65. A first ring 80b into which the bearing portion 66b is fitted is formed outside the opening 80a. Thus, if the collar 80 is prevented from touching the belt drive shaft 65, the belt drive shaft 65 can obtain more stable driving.

  A second ring 80c having an outer periphery substantially the same as the inner periphery of the wall portion 66c of the belt gear mechanism 66 is formed outside the first ring 80b. The second ring 80c is connected to the first ring 80b in the radial direction by the collar connecting portion 80d. The center in the thickness direction of the collar connecting portion 80d is located at the center of the ring width of the first ring 80b and the second ring 80c.

  The collar 80 formed in this way is lightly press-fitted between the bearing portion 66b and the wall portion 66c of the transfer belt gear mechanism 66 as shown in FIG. That is, the first ring 80b is fitted to the bearing portion 66b, and the second ring 80c is fitted to the wall portion 66c. In this embodiment, the collar 80 press-fitted into the transfer belt gear mechanism 66 is lightly press-fitted so as to be detached from the transfer belt gear mechanism 66 when pulled with a force of about 500 grams. The degree of press-fitting of the collar 80 into the transfer belt gear mechanism 66 may be within a range in which the space between the bearing portion 66b and the wall portion 66c of the transfer belt gear mechanism 66 is evenly supported and the wall portion 66c is not deformed. If the press-fit of the collar 80 to the transfer belt gear mechanism 66 is strong, the deformation of the wall portion 66c may affect the transfer belt gear portion 66a and cause tooth skipping during driving.

  Next, a printing process by the color printer apparatus 1 will be described. The color printer apparatus 1 includes a toner image forming unit 11 so that toner images are superimposed on a sheet paper P in the order of yellow (Y), magenta (M), cyan (C), and black (BK) to obtain a full color image. In FIG. 5, toner images are formed in the order of black (BK), cyan (C), magenta (M), and yellow (Y).

  When the document is read by the scanner 4 at the start of the image forming process, the drive motor 61 is driven in the printer 2. The drive of the drive motor 61 is transmitted from the motor drive gear 63 of the link mechanism 60 to the belt gear mechanism 72, and the transfer belt 21 is rotated in the arrow v direction. The drive of the drive motor 61 is further transmitted to the drum gear 74 via the drive gear 73 of the belt gear mechanism 72, and the photosensitive drum 10 is rotated in the arrow s direction at a speed slightly faster than the rotation speed of the transfer belt 21.

  As the photosensitive drum 10 rotates, it is charged by the charging device 12, an electrostatic latent image corresponding to the original is formed by the laser exposure device 13, and a toner image is formed by the black developing device 14 or the color developing device 20. Next, the toner image on the photosensitive drum 10 reaches a primary transfer position that is a contact position with the transfer belt 21 rotated in the direction of arrow v, and is primarily transferred onto the transfer belt 21 by applying a transfer bias from the primary transfer roller 37. The After the primary transfer, the photosensitive drum 10 is cleaned of residual toner by a cleaner device 22.

  Thereafter, the toner image forming process by the electrophotographic method is repeated on the photosensitive drum 10 for each color of each toner image, and a plurality of color toner images are sequentially primary-transferred and superimposed on the same position on the transfer belt 21. Then, a full color toner image is obtained on the transfer belt 21. Thereafter, the full color toner image on the transfer belt 21 reaches the secondary transfer position and is secondarily transferred onto the sheet paper P by the transfer bias of the secondary transfer roller 28. The sheet paper P is conveyed from the paper feeding device 3 to the secondary transfer position in synchronization with the full color toner image on the transfer belt 21 reaching the secondary transfer position. Thereafter, the sheet paper P is fixed with a full-color toner image by the fixing device 30 to complete the color image, and is accumulated in the paper discharge unit 24. On the other hand, after the transfer to the sheet paper P is completed, the transfer belt 21 is cleaned of residual toner by a belt cleaning device 37.

  During the image forming process, the transfer belt 21 is electrostatically attracted to the photosensitive drum 10 with a strong force by applying a transfer bias from the primary transfer roller 37. Further, the transfer belt 21 tries to rotate under the control of the photosensitive drum 10. As a result, a driving force from the driving motor 61 is transmitted, and a force in the arrow x direction opposite to the rotation direction is applied to the bearing portion 66b of the transfer belt gear mechanism 66 rotated in the arrow w direction. A high load is applied between the portion 66b and the transfer belt gear portion 66a.

  However, the transfer belt gear mechanism 66 is improved in rigidity by a collar 80 that is lightly press-fitted between the bearing portion 66b and the wall portion 66c, and is not deformed although a high load is applied. Accordingly, the driving force from the driving motor 61 is satisfactorily transmitted to the transfer belt 21 via the transfer belt gear mechanism 66, and the transfer belt 21 is stably rotated.

  According to this embodiment, the collar 80 is lightly press-fitted into the transfer belt gear mechanism 66 of the belt gear mechanism 72 that transmits the driving force of the drive motor 61 to the transfer belt 21 and the photosensitive drum 10, so that the rigidity of the transfer belt gear mechanism 66 is increased. Is increasing. Therefore, at the time of image formation, the force between the bearing portion 66b of the transfer belt gear mechanism 66 and the transfer belt gear portion 66a is increased by two forces, the driving force from the drive motor 61 and the force from the transfer belt 21 that attempts to rotate faster than this. Although a load is applied, the transfer belt gear mechanism 66 does not deform. As a result, the driving force of the driving motor 61 is satisfactorily transmitted to the transfer belt 21 via the transfer belt gear mechanism 66. The transfer belt 21 can obtain a high-quality transfer image without causing a speed fluctuation.

  Further, since the collar 80 supports the entire wall portion 66c evenly, the rigidity of the transfer belt gear portion 66a is increased evenly, and jitter does not occur on the image. Further, the rigidity of the transfer belt gear mechanism 66 can be easily increased only by lightly press-fitting a relatively low-cost collar 80 formed integrally with polyacetal resin into the transfer belt gear mechanism 66. Therefore, the reliability of the belt gear mechanism 72 can be improved without greatly increasing the cost.

  Further, in the transfer belt gear mechanism 66, since the center of the second connecting portion 66e in the thickness direction is located at the center of the gear width of the transfer belt gear portion 66a, the transfer belt gear portion 66a has uniform rigidity over the entire gear width. Can be held.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, the gear body is integrally formed to have a first gear mechanism and a second gear mechanism. The shape and material are not limited as long as they are made. The shape and material of the reinforcing member are not limited as long as the rigid body of the first gear mechanism can be increased between the bearing portion and the wall portion of the first gear mechanism. Further, the image forming apparatus is not limited to a printer, and may be a multi function peripheral or a facsimile.

1 is a configuration diagram schematically illustrating a color printer apparatus according to an embodiment of the present invention. 1 is a configuration diagram schematically illustrating a transfer belt device according to an embodiment of the present invention. It is a schematic perspective view which shows the link mechanism which transmits the drive of the drive motor of the Example of this invention. It is the schematic perspective view which looked at the belt gear mechanism of the Example of this invention from the drive gear side. It is the schematic perspective view which looked at the belt gear mechanism of the Example of this invention from the transfer belt gear part side. It is the schematic perspective view which looked at the color of the example of the present invention from the side facing a transfer belt gear part. It is the schematic perspective view which looked at the color of the example of the present invention from the opposite side of (Drawing 5-A). It is a schematic perspective view showing a transfer belt gear mechanism into which a collar according to an embodiment of the present invention is lightly press-fitted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Color printer apparatus 2 ... Printer 10 ... Photoconductor drum 11 ... Toner image formation part 12 ... Charging apparatus 13 ... Laser exposure apparatus 14 ... Black developing apparatus 20 ... Color developing apparatus 21 ... Transfer belt 32 ... Belt drive roller 32a ... Roller Support shaft 37 ... Primary transfer roller 40 ... Transfer belt device 61 ... Drive motor 63 ... Motor drive gear 64 ... Reduction gear mechanism 65 ... Belt drive shaft 66 ... Transfer belt gear mechanism 66a ... Transfer belt gear portion 66b ... Bearing portion 66c ... Wall portion 66d ... 1st connection part 66e ... 2nd connection part 72 ... Belt gear mechanism 73 ... Drive gear 74 ... Drum gear 75 ... Drum drive shaft 77 ... Drum shaft 80 ... Collar 80a ... Opening 80b ... 1st ring 80c ... 2nd ring

Claims (8)

In a drive transmission device having a gear body formed by integrally forming a first gear mechanism that transmits driving to the first driving unit and a second gear mechanism that transmits driving to the second driving unit,
The first gear mechanism includes a bearing portion through which a shaft is inserted, a wall portion that is radially connected to the bearing portion, and a first gear portion that is radially connected to the wall portion,
A drive transmission device comprising a reinforcing member that is lightly press-fitted between the bearing portion and the wall portion of the first gear mechanism.   The drive transmission device according to claim 1, wherein the reinforcing member has a disk shape that fits with an inner diameter of the wall portion.   The drive transmission device according to claim 1, wherein the reinforcing member does not contact the shaft.   2. The drive transmission device according to claim 1, wherein a center of a connecting portion that connects the wall portion and the first gear portion in a radial direction is located at a center of a gear width of the first gear portion.   The drive transmission device according to any one of claims 1 to 4, wherein the gear body and the reinforcing member are formed of the same material. A rotationally driven image carrier;
An endless transfer belt member facing the transfer position of the image carrier;
An image forming member for forming a toner image on the image carrier;
A drive source for rotationally driving the image carrier and the transfer belt member;
A belt drive gear for transmitting the drive by the drive source to the transfer belt member;
In an image forming apparatus having an image carrier driving gear that directly meshes with the belt driving gear and transmits driving by a driving source to the image carrier.
The belt drive gear has a gear body formed by integrally forming a first gear mechanism that transmits drive to the transfer belt member and a second gear mechanism that meshes with the image carrier drive gear,
The first gear mechanism includes a bearing portion through which a shaft is inserted, a wall portion that is radially connected to the bearing portion, and a first gear portion that is radially connected to the wall portion,
An image forming apparatus comprising: a reinforcing member that is lightly press-fitted between the bearing portion and the wall portion of the first gear mechanism.   The image forming apparatus according to claim 6, wherein the reinforcing member has a disk shape that fits with an inner diameter of the wall portion.   The image forming apparatus according to claim 6, wherein the gear body and the reinforcing member are formed of the same material.

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