JP2000075765A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the transmission error and rotation fluctuation of the driving force transmitted to each photoreceptor and form a color image of high quality with little convergence error by providing a process unit comprising two or more drive input means for driving photoreceptors and for driving other processing means such as developing means. SOLUTION: A photoreceptor unit 13 is formed of a photosensitive drum 1, and a charging roller 2 and a cleaning blade 6 as other process means. The photoreceptor unit 13 including the photosensitive drum 1 and other process means is integrated with a developing unit 4 for imaging a latent image formed on the photosensitive drum 1 to constitute a process unit, and the process unit is provided with two or more drive input means for driving photoreceptors and for driving other process means such as developing means. According to this, the photosensitive drum 1 is independently rotated, so that the influence of rotation fluctuation by the drive of the other process means is hardly reflected directly to the photosensitive drum 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus capable of forming a composite image by superimposing image information on a transfer material using an electrophotographic method or the like.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic method, an electrophotographic photosensitive member serving as an image carrier is charged by a charger, and the photosensitive member is irradiated with light according to image information to form a latent image. An image is formed, and an image obtained by developing the latent image with a developing device is transferred to a sheet material or the like to form an image.

On the other hand, a plurality of image carriers for each of these image forming processes are provided in accordance with the colorization of the image, and each of the color images of a cyan image, a magenta image, a yellow image, and preferably a black image is carried on each image carrier. A tandem-type image forming apparatus that forms a full-color image by superposing and transferring each color image on a sheet material at a transfer position of each image carrier at a transfer position of each image carrier has also been proposed.

Such a tandem multiplex image forming apparatus has an image forming section for each color, which is advantageous for speeding up.

FIG. 5 is a schematic view showing a conventional color image forming process. The sheet material 9 is fed from the right side in the figure, is charged and attracted to the conveyor belt 38, and moves to the left side in the figure. The color image is a Y, M, C, B photoconductor unit 13
In each process unit where d and the developing unit 4d are integrated, the image is transferred onto the sheet material 9 sequentially from the respective photoconductors 1 and then fused and press-fixed in a fixing device to complete the process.

Conventionally, a driving force transmission mechanism for driving each photoconductor 1 has a configuration as shown in the figure. The driving force supplied by one or a plurality of driving motors 29 provided at the end of the apparatus is transmitted to gears provided on the rotating shafts of the Y, M, C, and B photoconductors. Further, drive transmission to other process means is transmitted from a gear formed on a flange at the other end of the photoconductor 1 to a charging roller gear fixed to the charging roller 2 on the photoconductor unit side, and to a developing roller 4d on the developing unit 4d side. This is performed by direct mesh transmission of the gear to the developing gear fixed to the developing roller 15. Thereafter, the toner is transmitted to the toner supply roller 16 via the intermediate gear to the toner replenishing gear, and transmitted to an operation unit such as a toner stirring unit.

According to such a configuration, as the transmission path of the driving force becomes longer, the transmission error of the driving force transmitted from each photoconductor varies due to a manufacturing error of a gear interposed therebetween. Further, since the driving force is transmitted to the respective process means in the photoreceptor unit 13 and the developing unit 4 via the photoreceptor 1 by meshing the gears, the amount of image information formed on the photoreceptor, the toner storage in the developing unit Charging roller 2d, developing roller 15, toner supply roller 1 due to change in amount
6. Fluctuations in the rotational load of the toner stirring section directly affect the photoreceptor 1d, causing rotational fluctuations. like this,
There has been a problem that variations and rotation fluctuations in the transmission error of the driving force transmitted to each photoconductor cause color misregistration when forming a toner image on recording paper. In particular, in a process unit using a non-magnetic one-component developing method, in order to manage a contact nip width between the photosensitive member 1 and the developing roller 15, a photosensitive member,
Since the respective axial centers of the developing roller 15 are rotatably supported from both sides at a predetermined interval, the photosensitive member 1d and the developing roller 15 are brought into contact with each other with an excessive contact force. I have.

[0008]

As described above, in the conventional color image forming apparatus, variations in the transmission error of the driving force transmitted to each photoconductor and variations in the rotation fluctuation occur, and the variation on the recording paper occurs. There is a problem that color shift occurs when forming a toner image. Therefore, in the present invention, a color image capable of forming a high-quality color image with less color misregistration by minimizing the transmission error of the driving force transmitted to each photoconductor and the rotation fluctuation and solving the problem described above is minimized. It is an object to provide a forming device.

[0009]

In order to achieve the above object, according to the present invention, a plurality of process units in which a photosensitive unit and a developing unit are integrated are provided with a plurality of process units such as a photosensitive unit and a developing unit. Two or more drive input means for driving the photoreceptor, using an involute spline system to drive the photoreceptor to the main unit and drive transmission simultaneously, and to drive other process means by Oldham coupling And a non-magnetic one made up of a developing roller in which the developing means is provided with a conductive rubber layer by providing a rotating fulcrum of the developing unit on the photoreceptor unit side. Provided is a color image forming apparatus in which a pressing means for contacting a photosensitive member and a developing roller is provided by using a component developing method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a photoreceptor unit including a photoreceptor and other processing means, and a developing means for visualizing a latent image formed on the photoreceptor. Exposure means for irradiating each of the photoconductors with light to form a latent image, and speed adjusting means for changing the transfer speed of each of the photoconductors Transfer means for transferring the image visualized by the developing means to a transfer material, and forming a composite image by sequentially superimposing the visualized images on the transfer material on each of the photoconductors. In the multiplex image forming apparatus, the process unit is provided with two or more drive input units for driving the photosensitive member and for driving other process units such as the developing unit. Is driven to rotate by other Effect of the rotary drive fluctuation by Seth means drive is less likely to reflect directly the photoreceptor.

According to a second aspect of the present invention, in the first aspect of the invention, the photosensitive member is driven by an involute spline system, and the photosensitive member is positioned and transmitted to a main body device at the same time. The unit drive uses a coupling joint drive that can tolerate axial misalignment such as Oldham's coupling. This configuration enables high-precision positioning of the photoreceptor main unit, and the smoothness unique to the involute spline. The non-uniform engagement can reduce the non-uniform engagement of the photoconductor drive. In addition, by using a coupling joint drive that can tolerate a shift in the axial center for developing and other process means driving, it is possible to smoothly transmit the drive with respect to a position change of other process means.

According to a third aspect of the present invention, in the second aspect of the present invention, a rotation fulcrum of the developing unit is provided on the photoreceptor unit side, and the developing means is constituted by a developing roller coated with a conductive rubber. By using a non-magnetic one-component developing method, by providing a pressing means for bringing the photosensitive member and the developing roller into contact, the contact nip width between the photosensitive member and the developing roller can be controlled with a minimum necessary contact pressure. As a result, the influence of the fluctuation of the rotation of the developing roller on the photoconductor due to the fluctuation of the load on the developing roller and the operating part after the developing roller is minimized.

Hereinafter, embodiments of the present invention will be described. FIG. 1 is a configuration diagram of a color image forming apparatus according to an embodiment of the present invention, FIG. 2A is a schematic cross-sectional view of a color image forming apparatus according to an embodiment of the present invention, and FIG. FIG. 2C is a schematic side view of a color image forming apparatus according to an embodiment of the present invention, FIG. 2C is a schematic side view of the color image forming apparatus according to an embodiment of the present invention, and FIG. FIG. 4 is a schematic view of a process driving unit of a color image forming apparatus, and FIG.

First, FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. The image forming apparatus includes four image forming stations (hereinafter referred to as process units) Pa, Pb,
Pc, Pd are arranged, and each process unit Pa, P
b, Pc, and Pd denote photosensitive drums 1a as image carriers,
1b, 1c and 1d respectively.

[0015] In addition, dedicated charging means 2a,
2b, 2c, 2d, exposure means 3 for irradiating each photosensitive drum 1a, 1b, 1c, 1d with light corresponding to image information, developing means 4a, 4b, 4c, 4d, transfer means 5
a, 5b, 5c, 5d, cleaning means 6a, 6b,
6c and 6d are arranged respectively.

Here, the process units Pa, Pb, P
c and Pd are where a black image, a cyan image, a magenta image, and a yellow image are formed, respectively.

On the other hand, each process unit Pa, Pb, P
c, Pd, the photosensitive drums 1a, 1b,
An untransferred belt-shaped intermediate transfer belt 7 is arranged below 1c and 1d.

In such a configuration, first, a latent image of black component color of image information is formed on the photosensitive drum 1a by a known electrophotographic process means such as the charging means 2a of the first process unit Pa and the exposure means 3. Thereafter, the latent image is visualized as a black toner image by a developing material having black toner by a developing unit 4a, and the black toner image is transferred to the intermediate transfer belt 7 by a transfer unit 5a.

On the other hand, while the black toner image is being transferred to the intermediate transfer belt 7, a latent image of a cyan component color is formed in the second process unit Pb.
The cyan toner image is obtained by the cyan toner image, and the cyan toner image is transferred by the transfer means 5b of the second image station Pb to the intermediate transfer belt 7 where the transfer is completed in the first image station Pa, and the black toner image is Superimposed.

Hereinafter, the magenta toner image and the yellow toner image are formed in the same manner, and when the superposition of the four color toner images on the intermediate transfer belt 7 is completed, A four-color toner image is collectively transferred and conveyed by a sheet material transfer roller 11 onto a sheet material 9 such as paper fed from a sheet 10, and is heated and fixed by a fixing unit 12 to obtain a full-color image on the sheet material 9.

Each of the photosensitive drums 1a, 1b, 1c and 1d, to which the transfer has been completed, is a cleaning means 6a, 6b.
At b, 6c, and 6d, the residual toner is removed, and is prepared for the next image formation to be performed subsequently.

As described above, a plurality of process units P
a, Pb, Pc, and Pd, the photosensitive drum 1 is scanned by the scanning lines 3K, 3C, 3M, and 3Y of the laser beam emitted by the laser light source from the exposure unit 3.
Image information is exposed on a, 1b, 1c and 1d, and images of different colors are sequentially transferred to the same surface of the same intermediate transfer belt 7 conveyed in the direction of arrow A in the figure through a known image forming process. Each process unit Pa, Pb, P
If the rotation state of each photosensitive drum at c and Pd deviates from the ideal state, for example, in the case of a multicolor image, the image intervals of different colors are shifted or overlapped. Further, in the case of a color image, a difference in color tone, and if the degree of color difference becomes more severe, a color shift appears, which significantly deteriorates the image quality.

Therefore, in one embodiment of the present invention, a process unit as shown in FIG. 2 is used in order to minimize the fluctuation of the photosensitive drum rotation described in the prior art.
The photoreceptor unit 13 includes the photosensitive drum 1 and the charging roller 2 and the cleaning blade 6 as other process means. A flange having a female involute spline 19 is press-fitted on the rear side of the photosensitive drum 1 and is rotatably supported about a drum shaft 20 fixed and supported via bearings 21 and 22.
On the front side of the photosensitive drum 1, the drum shaft 2
A drum connecting gear 23 is provided to be rotatable coaxially with zero. A charging roller gear 24 is fixed to the front shaft side so that the charging roller 2 can rotate in contact with the photosensitive drum 1 while ensuring a predetermined bite amount.

The cleaning blade 6 is fixedly arranged at a predetermined position of the photosensitive drum 1 such that the tip thereof comes into pressure contact. The residual toner scraped off by the cleaning blade 6 is similarly carried out of the unit by a waste toner screw member 14 having a gear (not shown) that meshes with the drum connecting gear 23. The developing unit 4 includes a developing roller 15 that carries and rotates toner and a toner supply roller 1 that supplies toner to the developing roller 15.
6, a toner thinning member 17 for uniformly charging the toner layer on the developing roller 15 to a predetermined potential, a toner stirring member (not shown), and a toner replenishing means 18. On the rear side of the rotating shaft of the developing roller 15, a developing gear 26 integrally formed with a connecting lever and a gear, which is a part of an Oldham coupling often used as an axial center deviation allowable connecting joint, is fixedly supported. Is a developing transmission gear 27 so as to mesh with the drum connecting gear 23.
Is fixedly supported. The transmission of the driving force to the toner supply roller 16, the toner stirring member (not shown), and the toner supply means 18 is performed by a gear train 28 connected to the developing gear 26.

FIG. 3 shows a plurality of process units P
and a process drive unit for transmitting drive to a, Pb, Pc, and Pd. The process drive unit is connected to a male involute spline 32 by a belt 31 and a pulley 30 with a gear fixed to a rotation shaft of a main motor 29. The main motor 29
It is drivingly connected to an Oldham coupling gear 34 via a shaft pulley gear 30 and an idle gear 33. The photosensitive drum 1 is drivingly connected to the male involute spline 32, and the drum shaft 20 is inserted into a guide hole of the shaft 35 and positioned. Also,
The developing roller 15 is drivingly connected to the Oldham coupling gear 34, and the connecting portion 37 at the tip is swingable, so that a smooth driving connection is performed even if the axis of the developing gear connecting lever 26 is slightly shifted.

Further, as the developing method, the size of the apparatus can be reduced,
When using a developing unit employing a non-magnetic one-component contact developing system, which is expected to achieve high image quality, as shown in the figure, a photosensitive drum 1 and a developing roller 15 having a surface coated with conductive rubber are brought into pressure contact with each other. A rotation fulcrum 39 of the developing unit 4 is provided on the body unit 13 side, and pressing means 40 such as a spring is provided on both side surfaces.

As described above, the photosensitive unit 13 including the photosensitive drum 1 and other process means and the developing unit 4 having the developing means for visualizing the latent image formed on the photosensitive drum 1 are integrated. The process unit is provided with two or more drive input means for driving the photosensitive member and for driving other process means such as the developing means. With this configuration, the photosensitive drum 1 is independently driven to rotate, and other processes are performed. It becomes difficult for the influence of the rotation drive fluctuation due to the means driving to be directly reflected on the photosensitive drum 1.

Further, the photosensitive drum is driven by an involute spline system, the positioning of the photosensitive drum 1 to the main unit and the transmission of the drive are performed simultaneously, and the other process means is driven by an axial center displacement such as an Oldham coupling. With this configuration, the coupling joint drive can be used. With this configuration, the positioning accuracy of the main body of the photosensitive drum can be increased, and the unevenness of the drive of the photosensitive member can be reduced by the smooth engagement unique to the involute spline. In addition, by using a coupling joint drive that can tolerate a shift in the axial center for developing and other process means driving, it is possible to smoothly transmit the drive with respect to a position change of other process means.

Further, a rotation fulcrum of the developing unit is provided on the photosensitive member unit side, and the developing means is constituted by a non-magnetic one-component developing system comprising a developing roller coated with a conductive rubber. By providing the pressing means for bringing the developing roller into contact, the control of the contact nip width between the photosensitive member and the developing roller can be ensured with the minimum necessary contact pressure. The effect on the photoreceptor of fluctuations in the rotation of the developing roller due to load fluctuations is minimized.

[0030]

As described above, according to the present invention, a developing unit having a photosensitive unit including a photosensitive drum and other process means and a developing means for visualizing a latent image formed on the photosensitive drum is provided. A process unit in which the unit is integrated is provided with two or more drive input means for driving the photosensitive member and for driving other process means such as the developing means. With this configuration, the photosensitive drum is driven to rotate independently. In addition, it is difficult for the influence of the rotational drive fluctuation due to the driving of other process means to be directly reflected on the photosensitive drum.

Further, the photosensitive drum is driven by an involute spline system, the positioning of the photosensitive drum to the main unit and the transmission of the drive are performed simultaneously, and the other process means can be driven by an axial center displacement such as an Oldham coupling. It uses a coupling joint drive. With this configuration,
The positioning accuracy of the main body device of the photosensitive drum can be improved, and the unevenness of the driving of the photosensitive member can be reduced by the smooth engagement unique to the involute spline. In addition, by using a coupling joint drive that can tolerate a shift in the axial center for developing and other process means driving, it is possible to smoothly transmit the drive with respect to a position change of other process means.

Further, a rotating fulcrum of the developing unit is provided on the photoconductor unit side, and the developing means is constituted by a non-magnetic one-component developing system comprising a developing roller coated with a conductive rubber. By providing the pressing means for bringing the developing roller into contact, the control of the contact nip width between the photosensitive member and the developing roller can be ensured with the minimum necessary contact pressure. The effect on the photoreceptor of fluctuations in the rotation of the developing roller due to load fluctuations is minimized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a color image forming apparatus according to an embodiment of the present invention.

2A is a schematic cross-sectional view of a color image forming apparatus according to an embodiment of the present invention. FIG. 2B is a schematic plan cross-sectional view of a color image forming apparatus according to an embodiment of the present invention. 1 is a schematic side view of a color image forming apparatus according to an embodiment.

FIG. 3 is a schematic view of a process driving unit of the color image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a drive unit connection diagram of a color image forming apparatus according to an embodiment of the present invention;

FIG. 5 is a schematic view of a conventional color image forming apparatus.

[Explanation of symbols]

 1a photosensitive drum 2a charging means 3 exposure means 3K scanning line 4a developing means 5a transfer means 6a cleaning means 7 intermediate transfer belt 8 paper feed roller 9 sheet material 11 sheet material transfer roller 12 fixing means 13 photoreceptor unit 14 waste toner screw section 15 Development roller 16 Toner supply roller 17 Toner thin layer member

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H071 BA04 BA13 BA16 BA22 BA29 CA02 CA05 DA08 DA15 2H077 AD06 BA01 BA03 BA08 BA09 BA10 EA14 EA15 FA12 FA22 FA25 GA13

Claims (3)

[Claims] A plurality of process units each including a photoconductor unit including a photoconductor and other process means, and a development unit having a development unit for visualizing a latent image formed on the photoconductor. An exposure unit that irradiates each of the photoconductors with light to form a latent image, and a speed adjustment unit that changes a transfer speed of each of the photoconductors, and an image visualized by the developing unit is provided. Transfer means for transferring to a transfer material, wherein a superimposed image formed on each of the photosensitive members is sequentially superimposed on a transfer material to form a composite image. A color image forming apparatus comprising two or more drive input means for driving and for driving other process means such as developing means. 2. An involute spline system is used for driving the photoreceptor, positioning of the photoreceptor to the main unit and drive transmission are simultaneously performed, and misalignment of an axial center of an Oldham coupling or the like can be tolerated for driving other process means. 2. The color image forming apparatus according to claim 1, wherein a connection joint drive is used. 3. A non-magnetic one-component developing system in which a rotation fulcrum of a developing unit is provided on the photoreceptor unit side and the developing means is constituted by a developing roller coated with a conductive rubber.
3. A color image forming apparatus according to claim 2, further comprising a pressing unit for bringing said photosensitive member into contact with said developing roller.