JP2000227696A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize, without a decrease in recording speed, phase shift between colors on an intermediate transfer body resulting from a change in load on rotation, to accordingly eliminate color slippage, and to obtain a satisfactory color image free from banding. SOLUTION: This color image forming device composes a drive sub-unit by mounting or supporting, on one support bracket 90, intermediate pulleys 44, 47, and 49, belts 45 and 50, gears 48 and 51, an intermediate-transfer-body drive shaft 80, a photoreceptor drive shaft 81, couplings 46a and 52a, a bearing 82, an intermediate-transfer-body sub-bracket 83, and a photoreceptor sub-bracket 84. The support bracket 90 is positioned and attached to the side plate of the main body of a printer device, and connected to a process cartridge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser printer, a laser copying machine, a laser facsimile, or a multifunction machine thereof, and more particularly to a type for driving an image carrier and a belt-shaped intermediate transfer member. A color image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic color image forming apparatus, a color shift due to a phase shift between respective colors and a fixed pitch image disorder, that is, banding may occur.
One of the causes is the uneven rotation speed of the photosensitive member and the intermediate transfer member, which are image carriers. The causes of the rotational speed unevenness include unevenness in the rotational speed of the drive motor itself, unevenness in the pitch of the gear or eccentricity of the pitch circle, etc., and manufacturing error of the drive transmission means, and fluctuations in the rotational load applied to the photoconductor and the intermediate transfer body. May be mentioned.

For example, Japanese Patent Application Laid-Open No. 8-137180 discloses
As described in Japanese Patent Application Laid-Open No. H10-209, the photoreceptor and the intermediate transfer body are driven by a single drive motor, and drive transmission means for transmitting rotation to the photoreceptor and the intermediate transfer body are formed by using gears having the same shape. There is an attempt to solve the problem caused by the above. In addition, as disclosed in Japanese Patent Application Laid-Open No. 8-227200, there is a method in which a toothed belt is used as a drive transmission unit to obtain the same effect.

[0004]

When such a conventional technique is used, a certain effect can be obtained when the next recording is started after the color image of the intermediate transfer body is collectively transferred and color recording is completed on paper. However, since the image forming speed is reduced, it is actually necessary to start the next recording before the end of the color image formation. Then, fluctuations in the rotational load on the intermediate transfer body that occur during transfer of the synthetic toner image formed on the intermediate transfer body and during cleaning of the intermediate transfer body affect the next image formation, and eventually cause color misregistration of the color toner image on the intermediate transfer body. Can be caused. In particular, when the drive transmission path from the drive motor to the intermediate transfer member is long, this problem occurs remarkably.

Accordingly, the present invention reduces the phase shift between the respective colors of the intermediate transfer member caused by the fluctuation of the rotational load without lowering the image forming speed, thereby increasing the position accuracy of the color superimposition.
It is another object of the present invention to provide a color image forming apparatus capable of obtaining a good color image without banding.

[0006]

According to a first aspect of the present invention, there is provided a color image forming apparatus comprising an image carrier and a belt-shaped intermediate transfer member, and the image transfer device is configured to transfer the image from the image carrier to the intermediate transfer member. In a color image forming apparatus for forming a multicolor composite toner image by sequentially superimposing and transferring the monochromatic toner images to form a multicolor composite toner image and forming a color image on paper, the driving shaft of the image carrier is And a drive unit of the intermediate transfer member and a common support, and a means for connecting these drive shafts is also held by the support to form a subunit. The subunit is assembled to the image forming apparatus main body. It is characterized by being made possible.

According to a second aspect of the present invention, the drive shaft of the image carrier and the drive shaft of the intermediate transfer member are connected to a driven shaft of the image carrier and a driven shaft of the intermediate transfer member, respectively. The portion is provided with a coupling member that absorbs axial center deviation, eccentricity, axis angle deviation, and the like of each shaft.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the overall schematic configuration of a color laser printer as one embodiment of a color image forming apparatus according to the present invention. In the figure, reference numeral 10 denotes a printer main body, which is provided with a photoreceptor 11 slightly in the center of the outer case 12 (rightward in the figure). The photoconductor 11 is
As shown in FIG. 2, the driving roller 11a and the driven roller 11b
The belt-like body is wrapped around endlessly between them.

Around the photoreceptor 11, a charging device 13 provided below the photoreceptor 11 conveys the photoreceptor 11 in a conveying direction a indicated by an arrow in FIG.
, A multicolor developing device 14, a black developing device 15, an intermediate transfer belt 16, a photoreceptor cleaning device 17, and a static eliminator 18 in this order. Further, a laser writing device 19 is provided below the multicolor developing device 14.

As shown in FIG. 3, the multicolor developing device 14 is provided with a support frame 14c supported by a central shaft 14b in a cylindrical case 14a, and a developing frame in which a yellow developer is stored in the support frame 14c. And a developing device containing a magenta developer and a developing device containing a cyan developer. Then, the support frame 14c is rotated about the center shaft 14b, so that the developing rollers of the respective developing units can come into contact with the photoconductor 11 sequentially.
As shown in FIG. 2, each of the developing devices has a first developer conveying member 60 having a screw shape and a second developer conveying member 6 having a screw shape.
1. The supply roller 62 and the developing roller 63 are provided in parallel with each other. Also, at one end of the multicolor developing device 14,
As shown in FIG. 3, a fan-shaped developer storage section 65 for each color is provided.
And a developer cartridge 66 for replenishing the developer to the developer storage section 65 is detachably attached to the outside of each developer storage section 65.

The black developing device 15 has a developing case 15
a, agitators 15b and 15c, supply roller 15d
And a developing roller 15e, etc., which is normally urged by a spring toward a cam (not shown) provided on the left side in the drawing, and rotates the cam to bring the developing roller 15e into appropriate contact with the photoconductor 11 in use. .

The intermediate transfer belt 16 includes a driving roller 16a
And the driven roller 16b is endlessly wound, and a part thereof is brought into contact with the photosensitive member 11. A photoconductor image transfer device 16d is provided inside the contact position. And
The transfer roller 21a of the composite image transfer device 21 is pressed against the outer periphery of the drive roller 16a from the right side in the figure, and the cleaning member 2 of the intermediate transfer body cleaning device 22 is pressed from the left side.
2a is pressed. The transfer roller 21a and the cleaning member 22a can be moved by a contact / separation mechanism (not shown), and are appropriately brought into contact with / separated from the intermediate transfer belt 16 during recording.

The photoreceptor cleaning device 17 presses the cleaning member 17a against the outer periphery of the drive roller 11a of the photoreceptor 11, removes the residual developer on the photoreceptor 11 after image transfer by the cleaning member 17a, and collects it inside. It is something to keep.

The laser writing device 19 irradiates a laser beam L based on the write information, performs writing at an image writing position A provided on the outer periphery of the driving roller 11a, and forms an electrostatic latent image on the photoconductor 11.

The printer main body 10 includes a fixing device 24 above the black developing device 15, a paper discharge roller pair 25 on the left side of the fixing device 24 in the drawing, and a discharge roller 25 on the left side of the printer main body 10. The paper stack unit 26 is provided. The fixing device 24 includes a fixing roller 24a having a built-in heater, a pressure roller 24b pressed against the fixing roller 24a, and an oil supply mechanism 24c for applying oil to the peripheral surface of the fixing roller 24a.

Although not shown, the printer body 10 is provided with an electrical device on the left side of the multicolor developing device 14 in the figure and a ventilation fan on the upper side.
Further, a paper feed cassette 28 for storing the paper P is provided at the bottom so as to be freely taken in and out.

When performing image formation and recording using this color printer, the paper P in the paper feed cassette 28 is fed by rotating the paper feed roller 29, and is conveyed through the paper feed path 31 by the conveyance roller pair 30. The photosensitive member 11 is conveyed in the direction of arrow a in the figure, and the intermediate transfer belt 16 is conveyed in the direction of arrow b. First, the surface of the photoconductor 11 is uniformly charged by the charging device 13 as the photoconductor 11 is transported, and then the laser light L is irradiated by the laser writing device 19 based on the first color writing information. To form an electrostatic latent image of the first color. Then, at the position of the multicolor developing device 14, the first developing device moved to the developing position in contact with the photoreceptor 11 adheres the developer of the first color and develops the electrostatic latent image to form a visible image. The image is temporarily transferred onto the intermediate transfer belt 16 by the photoconductor image transfer device 16d. Thereafter, the residual developer of the first color remaining on the photoconductor 11 is removed from the cleaning member 1 of the photoconductor cleaning device 17.
Remove at 7a.

Thereafter, when forming images of the second and third colors, laser writing is performed in the same manner as described above based on the respective writing information to form respective electrostatic latent images, and the second and third colors are formed. Are moved to a developing position in contact with the photoreceptor 11 to develop an electrostatic latent image, these visible images are respectively transferred onto the intermediate transfer belt 16, and the surface of the photoreceptor 11 is cleaned after image transfer. . When a black developer is used, laser writing is performed based on the write information to form an electrostatic latent image, and the developing roller 15 e of the black developing device 15 is brought into contact with the photoconductor 11 in the same manner as described above. Develop the latent image,
The visible image is transferred onto the intermediate transfer belt 16, and the surface of the photoconductor 11 is cleaned after the image is transferred. The photoconductor 1
After each cleaning of 1, the surface is neutralized by the neutralization device 18 to prepare for the next writing.

After forming a composite color image on the intermediate transfer belt 16 as described above, the composite image transfer device 21
Transfer roller 21a and intermediate transfer body cleaning device 2
While the second cleaning member 22a is moved to contact the intermediate transfer belt 16, the sheet P is conveyed between the transfer roller 21a and the intermediate transfer belt 16 at a timing by the registration roller pair 32. Then, the composite color image on the intermediate transfer belt 16 is transferred to the lower surface of the sheet P by the transfer roller 21a. The paper P after the image transfer is transferred to the fixing roller 24 a and the pressure roller 2
4b, the transfer image is fixed by applying heat and pressure between the rollers, and then discharged by the discharge roller pair 25 from the discharge port 34 onto the discharge stack section 26 to be sequentially stacked.
On the other hand, after the image is transferred onto the intermediate transfer belt 16, the developer remaining on the intermediate transfer belt 16 is cleaned by the cleaning member 22 a of the intermediate transfer body cleaning device 22, and the collected developer is transferred to the photoconductor cleaning device 17. Transport.

In the illustrated color printer, the photosensitive member 1
1 and the intermediate transfer belt 16 together with the charging device 13, the intermediate transfer body cleaning device 22, the registration roller pair 32, and the like, are made removable as a process cartridge 35 with respect to the printer main body 10 as shown in FIG. The process cartridge 35 includes an intermediate transfer member driven shaft 70 that projects to the outside and drives the intermediate transfer belt 16, and a photosensitive member driven shaft 71 that drives the photosensitive member 11. Couplings 46 and 52 are provided at shaft ends as relay means for transmitting a driving force from a driving source (not shown) to the intermediate transfer member driven shaft 70 and the photosensitive member driven shaft 71. The couplings include drive couplings 46a and 52a attached to the intermediate transfer member drive shaft 80 and the photosensitive member drive shaft 81 on the drive source side, and a driven coupling 46 attached to the intermediate transfer member driven shaft 70 and the photosensitive member driven shaft 71.
b and 52b. Of course, when removing the process cartridge 35 from the apparatus main body, it is necessary to open the front frame of the printer apparatus main body 10 and to disconnect the couplings 46 and 52 before the operation of removing the process cartridge 35. .

FIG. 5 shows the photosensitive member 11 and the intermediate transfer belt 1.
It is a perspective view which shows the 6 rotation drive mechanism. This mechanism transmits the rotation of the drive motor 40 to the intermediate transfer belt 16 via the first drive transmission unit 41, and then to the photoconductor 11 via the second drive transmission unit 42. The first drive transmission means 41 includes a motor pulley 43 and a first intermediate pulley 44.
A first drive transmission belt 45 using a timing belt with teeth is interposed therebetween, and a drive coupling 46 a of the first coupling 46 is provided coaxially with the first intermediate pulley 44. On the other hand, the second drive transmission means 42
A second intermediate pulley 47 provided coaxially with the first intermediate pulley 44, and a third intermediate pulley 49 provided coaxially with the first drive transmission gear 48.
The first drive transmission gear 48 is meshed with the second drive transmission gear 51, and the drive coupling 52 a of the second coupling 52 is coaxial with the second drive transmission gear 51. It is provided and configured. The couplings 46a, 46b, 52a, and 52b are connected to the intermediate transfer member drive shaft 80 and the intermediate transfer member driven shaft 70 by using an Oldham coupling, and the axes of the respective axes between the photosensitive member drive shaft 81 and the photosensitive member driven shaft 71. It is preferable to be able to absorb misalignment, eccentricity during rotation, and misalignment of the axis angle.

When the process cartridge 35 is attached to the printer main body 10, the first coupling 46
Of the driven coupling 46a to the driven coupling 46a
To the driven coupling 52b of the second coupling 52.
And a drive coupling 52a, and the photoreceptor 11 and the intermediate transfer belt 16 are connected to first and second drive transmission means 41 and 42 provided on the printer apparatus main body 10 via respective couplings 46 and 52. . Thus, the photoconductor 11 and the intermediate transfer belt 16 can be driven by one drive motor 40.

In the color printer according to the present embodiment, as shown in FIG. 6, the intermediate pulleys 44, 47, 49, belts 45, 50,
Gears 48 and 51, intermediate transfer member drive shaft 80, photosensitive member drive shaft 81, and couplings 46a and 52a, bearing 82
.., The intermediate transfer member sub-bracket 83 and the photoreceptor sub-bracket 84 are attached or supported to form a drive sub-unit.

The support bracket 90 has a hole 91 for mounting the intermediate transfer member drive shaft 80 and its bearing 82, a hole 92 for mounting the photosensitive member drive shaft 81 and its bearing 82,
Pins 93 for attaching the intermediate transfer member sub-bracket 83 and the photoreceptor sub-bracket 84 and small holes 94 for attaching to the side plate 10a of the printer main body 10 side.
... is provided. Intermediate transfer member sub-bracket 8
3 and a photoreceptor sub-bracket 84 are also plate-shaped members, and a hole 95 for mounting the intermediate transfer member drive shaft 80 and its bearing 82, a hole 96 for mounting the photoconductor drive shaft 81 and its bearing 82, respectively, Pin 93 of bracket 90
There are provided small holes 97. On the other hand, the side plate 10a on the side of the printer body 10 has a hole 98 for passing the intermediate transfer member drive shaft 80, the photosensitive member drive shaft 81 and the drive couplings 46a and 52a at their ends, and a small hole 94 of the support bracket 90. Are provided for attaching the support bracket 90 through the holes. In addition,
The intermediate pulleys 44 and 47, the gear 48 and the pulley 49
Although shown as a separate body in FIG. 5, it is shown in FIG. 6 as being integrated and suitable for unitization.

FIG. 7 is a cross-sectional view of the assembled state of the drive subunit shown in FIG. 6 as viewed from the front side. In this figure, a flywheel 85 not shown in FIG.
Reference numerals 86 are provided at shaft ends of the intermediate transfer member drive shaft 80 and the photosensitive member drive shaft 81, respectively. That is, if most of the components of the drive system of the photoconductor 11 and the intermediate transfer belt 16 are unitized as described above and integrally supported and held, the rotational speed of the photoconductor 11 and the intermediate transfer belt 16 becomes uneven. It is possible to prevent the occurrence of manufacturing accuracy errors such as uneven pitch of gears and eccentricity of pitch circles, and fluctuations in rotational load.

In the illustrated embodiment, the support bracket 90 has a simple rectangular plate shape. However, it is practical that the support bracket 90 has a shape that is variously deformed according to the installation space inside the printer apparatus main body 10. . Of course, the shape is not limited to a plate shape, and may be a dish shape or the like.

[0027]

As described above, the color image forming apparatus according to the first aspect of the present invention has an intermediate position between the image carrier and the image carrier which determines the color overlay position accuracy and banding, which are important qualities for maintaining image quality in the color image forming apparatus. The drive system of the transfer body is made into a sub-unit, which can be assembled into the main body of the image forming apparatus. Therefore, it is possible to easily check the quality assurance with a single unit and maintain the positional accuracy in the main body of the image forming apparatus. The installation is easy, and therefore, there is an effect that the workability when the maintenance is performed by the service person is also improved.

According to a second aspect of the present invention, there is provided a color image forming apparatus wherein the drive shaft of the image carrier and the drive shaft of the intermediate transfer member are connected to the driven shaft of the image carrier and the intermediate transfer member, respectively. In addition, in addition to the above-mentioned common effects, in addition to the above-described common effects, the rotational speed unevenness due to the axial center deviation of each shaft is provided in the portion. Not only can be prevented, but also there is an effect that the mounting position accuracy to the image forming apparatus main body has a margin.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall schematic configuration of a color laser printer as an embodiment of a color image forming apparatus according to the present invention.

FIG. 2 is a partially enlarged view around a developing device of the apparatus of FIG. 1;

FIG. 3 is a perspective view of a multicolor developing device used in the apparatus of FIG.

FIG. 4 is a perspective view showing an appearance of a process cartridge used in the apparatus of FIG.

FIG. 5 is a perspective view showing a drive transmission system to a photoconductor and an intermediate transfer belt in the process cartridge of FIG. 4;

FIG. 6 is an exploded perspective view showing a sub-unit of the drive system in FIG. 5;

FIG. 7 is a front view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Printer apparatus main body 10a Printer apparatus main body side plate 11 Photoconductor 13 Charging device 16 Intermediate transfer belt 17 Photoconductor cleaning device 21 Synthetic image transfer device 22 Intermediate transfer member cleaning device 32 Registration roller pair 35 Process cartridge 40 Drive motor 41, 42 Drive Transmission means 45, 50 Drive transmission belt 46, 52 Coupling 46a, 52a Drive coupling 46b, 52b Followed coupling 48, 51 Drive transmission gear 70 Intermediate transfer member driven shaft 71 Photoconductor driven shaft 80 Intermediate transfer member drive shaft 81 Photosensitive Body drive shaft 82 Bearing 83 Intermediate transfer member sub-bracket 84 Photoreceptor sub-bracket 85, 86 Flywheel 90 Support bracket

Claims (2)

[Claims] An image carrier and a belt-shaped intermediate transfer member, wherein a monochromatic toner image is sequentially superimposed on the image carrier and transferred to the intermediate transfer member to form a multicolor composite toner image; In a color image forming apparatus for forming a color image on a sheet by collectively transferring the synthetic toner image, the driving shaft of the image carrier and the driving shaft of the intermediate transfer member are held on a common support, and both driving shafts are driven. A color image forming apparatus, wherein the means for connecting the shafts is also held as a subunit by holding the support, and the subunit can be assembled to the image forming apparatus main body. 2. The drive shaft of the image carrier and the drive shaft of the intermediate transfer member are connected to the driven shaft of the image carrier and the driven shaft of the intermediate transfer member, respectively. Misalignment,
2. The color image forming apparatus according to claim 1, further comprising a coupling member that absorbs eccentricity, deviation of an axis angle, and the like.