JPH11327241A - Electrophotographic image forming device, electrophotographic photoreceptor drum, intermediate transfer body and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly move an electrophotographic photoreceptor drum, a developing roller and an intermediate transfer body and to obtain an excellent image output by fitting a massive body to the inside of the electrophotographic photoreceptor drum or the intermediate transfer body through a visco-elastic body. SOLUTION: The massive body 203 is fitted to a drum shaft 15a arranged in a cylinder 15b through the visco-elastic body 202 in order to suppress the shock and the rotational irregularity of the photoreceptor drum caused by disturbance without drastically increasing mass. In a fitting method, a boss 204 supporting the massive body (fitted through a visco-elastic body member 202) 203 is force-fitted or engaged in the drum shaft 15a and fixed by a set screw 302. The massive body 203 fitted to the driving shaft 15 on a driving side (right side) is set to be larger than the massive body 203 fitted to the driving shaft 15a on a non-driving side (left side). That means, when the photoreceptor drum is displaced in a horizontal and a vertical directions, the massive body 203 receiving the effect of a shaft joint more is made large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrophotographic image forming apparatus for forming a multicolor image, and an electrophotographic photosensitive drum, an intermediate transfer member, and a process cartridge constituting the electrophotographic image forming apparatus. Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming method. Examples of the electrophotographic image forming apparatus include, for example, an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, and the like), a facsimile machine, a word processor, and the like.

Further, a process cartridge used in an electrophotographic image forming apparatus for forming a multicolor image is a cartridge in which a charging means, a cleaning means and an electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is attached to the main body of the image forming apparatus. It is made detachable. In addition, the cleaning means and the electrophotographic photosensitive member are integrally formed into a cartridge so that the cartridge can be attached to and detached from the image forming apparatus main body. Since such a process cartridge can be attached to and detached from the apparatus main body by a user himself, maintenance of the apparatus main body can be easily performed.

[0003]

The present invention is a further development of the prior art.

The present invention relates to an electrophotographic photosensitive drum, a developing roller which rotates in synchronism with the electrophotographic photosensitive drum, and a process cartridge which can obtain a good image output by obtaining a smooth movement of an intermediate transfer member. It is an object of the present invention to provide a possible electrophotographic image forming apparatus, an electrophotographic photosensitive drum, an intermediate transfer member, and a process cartridge.

[0005]

The main aspects of the present invention are as described below with reference to the claims.

According to a first aspect of the present invention, there is provided an electrophotographic image forming apparatus capable of forming a multicolor image on a recording medium by detachably attaching a process cartridge, comprising: a process cartridge having an electrophotographic photosensitive drum and cleaning means;
A developing device having a developer carrier for pressing a latent image formed on the electrophotographic photosensitive drum by using the toner by pressing against the electrophotographic photosensitive drum; and a toner formed on the electrophotographic photosensitive drum. An intermediate transfer member on which images are multiplex-transferred,
The photosensitive drum has an oscillating center axis that is parallel to the longitudinal direction of the electrophotographic photosensitive drum and moves along an arc locus about the center of rotation, and the developer is developed so that the developer carrier oscillates about the oscillating center axis. Developing device moving means having an elastic member which supports the developing device and presses the developer carrier so as to be able to advance and retreat in a substantially radial direction with respect to the electrophotographic photosensitive drum; and mounting means for detachably mounting the process cartridge. And a mass body attached to the inside of the electrophotographic photosensitive drum or the intermediate transfer body via a viscoelastic body.

According to an eighth aspect of the present invention, there is provided a hollow cylindrical cylinder having a photosensitive layer on the outer periphery, a flange attached to both ends of the cylinder, a center shaft fixed to the center of the flange, and An electrophotographic photosensitive drum, comprising: a mass body attached via an elastic body.

According to a ninth aspect of the present invention, there is provided a flange portion for connecting a hollow cylindrical cylinder portion having a dielectric material on an outer periphery thereof to a center shaft provided at the center of the cylinder portion, and the center shaft or the flange portion. And a mass body attached to a central portion of the intermediate transfer member via a viscoelastic body.

According to a tenth aspect of the present invention, there is provided a process cartridge detachably mountable to a main body of an image forming apparatus for forming a multi-color image, wherein the electrophotographic photosensitive drum and the electrophotographic photosensitive drum remain after being transferred to the electrophotographic photosensitive drum. Cleaning means for removing toner, wherein the electrophotographic photosensitive drum is a hollow cylindrical cylinder having a photosensitive layer on the outer periphery, flanges attached to both ends of the cylinder, and fixed to the center of the flange. A process cartridge having a central axis and a mass attached to the central axis via a viscoelastic body.

[0010]

2. Description of the Related Art Conventionally, in a multicolor electrophotographic image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive drum and process means excluding a developing means acting on the electrophotographic photosensitive drum are integrally formed. A process cartridge system is adopted in which the cartridge is formed into a cartridge and the cartridge is detachably mountable to the main body of the electrophotographic image forming apparatus. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself without relying on a serviceman, so that the operability can be remarkably improved. Therefore, the process cartridge system is widely used in a multicolor electrophotographic image forming apparatus.

Such a process cartridge is mounted on the electrophotographic image forming apparatus body by inserting the process cartridge into the mounting means of the electrophotographic image forming apparatus body, and the process cartridge is fixed at a fixed position. A plurality of cylindrical developer carriers of developing means are selectively pressed against the electrophotographic photosensitive drum of the process cartridge or the electrophotographic photosensitive member directly mounted on the electrophotographic image forming apparatus main body. The developing means is devised as described above.

In order to drive the photosensitive drum, it is common to use a method in which a coupling comes out from the apparatus main body side and is fitted to a shaft of the photosensitive drum.

The respective color toner images formed on the photosensitive drum are transferred onto the intermediate transfer member in a superimposed manner.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) The term "longitudinal direction" in the present embodiment refers to a direction perpendicular to the transfer direction of a transfer material (recording medium) and parallel to the transfer material.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

[Overall Description of Electrophotographic Image Forming Apparatus] First, the overall configuration of a color electrophotographic image forming apparatus will be schematically described with reference to FIG.

FIG. 1 is an explanatory view of the overall configuration of a laser printer which is an embodiment of a color electrophotographic image forming apparatus.

As shown in FIG. 1, the color laser printer includes an electrophotographic photosensitive drum (hereinafter referred to as a photosensitive drum) 15 serving as an image carrier rotating at a constant speed, a fixed black developing unit 21B, and a photosensitive drum 15. An image forming unit having three color developing units 20Y, 20M, and 20C that can be indexed and rotated, and a color image developed and multi-transferred in the image forming unit is held on the transfer material 2 fed from the feeding unit. And an intermediate transfer member 9 for transferring. The transfer material 2 onto which the color image has been transferred is then conveyed to the fixing unit 25 to fix the color image on the transfer material 2 and discharged to discharge units 37 on the upper surface of the apparatus by discharge rollers 34, 35, and 36. In addition, the color developing devices 20Y, 20M, which can be indexed and rotatable,
20C and the fixed black developing unit 21B are configured to be individually detachable from the electrophotographic image forming apparatus main body 18.

Next, the configuration of each part of the electrophotographic image forming apparatus will be sequentially described in detail.

[Process Cartridge] The process cartridge 13 integrally includes a photosensitive drum 15, a cleaning blade 16, a primary charging unit 17, and a cleaning container 14 also serving as a holder for the photosensitive drum 15. The cartridge is detachably supported on the main body 18 of the electrophotographic image forming apparatus, and is configured such that each cartridge can be easily replaced according to the life of the photosensitive drum 15. The photoconductor drum 15 according to the present embodiment is formed by applying an organic photoconductor layer to the outside of an aluminum cylinder, and is rotatably supported by a cleaning container 14 also serving as a holder for the photoconductor drum 15.
A cleaning blade 16 and a primary charging unit 17 are provided around the photosensitive drum 15 in the cleaning container 14.
Are disposed, and the photosensitive drum 15 is partially exposed to the outside of the cleaning container 14. Also shown photosensitive drum 15
By transmitting the driving force of a driving motor (not shown) to one end behind the photosensitive drum 15, the photosensitive drum 15 is rotated counterclockwise in the drawing in accordance with the image forming operation.

The charging means 17 provided in the process cartridge 13 employs a contact charging method, in which a conductive roller is brought into contact with the photosensitive drum 15 and a voltage is applied to the conductive roller. 15 to uniformly charge the surface.

The process cartridge is a cartridge in which a charging unit, a cleaning unit, and an electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is detachable from an electrophotographic image forming apparatus main body. In addition, at least one of the charging means and the cleaning means and the electrophotographic photosensitive member are integrally formed into a cartridge so that the cartridge can be attached to and detached from the electrophotographic image forming apparatus main body.

[Exposure Means] Exposure to the photosensitive drum 15 is performed from the scanner unit 30. That is, when an image signal is given to the laser diode, the laser diode irradiates the polygon mirror 31 with image light corresponding to the image signal. The polygon mirror 31 is rotated at a high speed by a scanner motor, and the image light reflected by the polygon mirror 31 selectively exposes the surface of the photosensitive drum 15 rotating at a constant speed through the imaging lens 32 and the reflection mirror 33 to thereby expose the surface. As a result, an electrostatic latent image is formed on the photosensitive drum 15.

[Developing Means] The developing means 20 and 21 are provided for yellow, magenta,
Three developing units 20 capable of developing each color of cyan and black
Y, 20M, 20C and one black developing unit 21B. The developing means 20 will be described in more detail later.

The black developing device 21B of the developing means 21 is a fixed developing device, and a developing roller 21BS as a developer carrier is disposed at a position opposed to the photosensitive drum 15 at a small interval from the photosensitive drum 15. A toner image is formed on the drum 15 using black toner.

The black developing device 21B feeds the toner in the container by a feeding mechanism, and applies a thin layer of toner to the outer periphery of the developing roller 21BS which rotates clockwise in FIG. 1 by an application blade 21BB pressed against the outer periphery of the developing roller 21BS. And charge is applied to the toner (frictional charging).
Further, by applying a developing bias to the developing roller 21BS, toner is supplied to the photosensitive drum 15 to perform toner development corresponding to the electrostatic latent image on the photosensitive drum 15.

[Sheet Feeding Section] The sheet feeding section transfers the transfer material 2 to the image forming section.
The paper feed cassette 1 containing a plurality of transfer materials, the paper feed roller 3, the feed roller 4, the retard roller 5 for preventing double feed, the paper feed guide 6, and the registration roller 8 are mainly used. Be composed. During image formation, the paper feed roller 3 is driven and rotated in accordance with the image forming operation, separates and feeds the transfer material 2 in the paper feed cassette 1 one by one, and is guided by the paper feed guide 6 via the transport roller 7. To the registration roller 8. During the image forming operation, the registration roller 8 performs a non-rotating operation of stopping the transfer material 2 in a standby state and a rotating operation of transporting the transfer material 2 toward the intermediate transfer body 9 in a predetermined sequence, which is the next step. The image and the transfer material 2 at the time of the transfer step are aligned.

[Transfer Section] The transfer section includes a swingable transfer roller 10.

The transfer roller 10 has a metal shaft wound around a medium-resistance foamed elastic body, is movable up and down in the figure, and rotates by receiving a driving force. While forming the four-color toner image on the intermediate transfer member 9, that is, while the intermediate transfer member 9 rotates a plurality of times, the transfer roller 10 is positioned below as shown by a solid line in the drawing so as not to disturb the image. It is separated from the intermediate transfer member 9.
After the four color toner images have been formed on the intermediate transfer member 9, the transfer roller 10 is moved by a cam member (not shown) to an upper position indicated by a thin line in FIG. It is pressed against the intermediate transfer body 9 via the material 2 with a predetermined pressure. At this time, a bias is applied to the transfer roller 10 at the same time, and the toner image on the intermediate transfer body 9 is transferred to the transfer material 2. Here, since the intermediate transfer member 9 and the transfer roller 10 are driven respectively, the transfer material 2 sandwiched between the two is transferred at a predetermined speed to the left in the figure at the same time as the transfer process is performed, and is transferred to the next process. Is sent to the fixing unit 25.

[Fixing Section] The fixing section 25 is provided with the developing means 2
The toner image formed on the transfer material 2 is fixed on the transfer material 2 via the intermediate transfer member 9 with the toner image formed by the transfer media 0 and 21. As shown in FIG. A roller 26 and a pressure roller 27 for pressing the transfer material 2 against the fixing roller 26. Each roller is a hollow roller and has heaters 28 and 29 inside.
And is configured to be driven to rotate and to simultaneously transfer the transfer material 2.

That is, the transfer material 2 holding the toner image is conveyed by the fixing rollers 26 and 27, and the toner is fixed to the transfer material 2 by applying heat and pressure.

[Image Forming Operation] Next, the operation in the case where an image is formed by the above-configured apparatus will be described with reference to FIG.

First, the paper feed roller 3 shown in FIG. 1 is rotated to separate one sheet of the transfer material 2 in the paper feed cassette 1, and is conveyed to the registration roller 8.

On the other hand, the photosensitive drum 15 and the intermediate transfer member 9 are driven and rotated at the same outer peripheral speed in the direction indicated by the arrow.

The three developing units 20Y and 20 of the developing means 20
M and 20C are each detachably held by a developing rotary 23 that rotates about a center shaft 22. At the time of image formation, each developing device is rotated about the center shaft 22 while the developing devices are held by the developing rotary 23. , A predetermined developing device is stopped at a position facing the photosensitive drum 15, and furthermore, a developing roller 20YS (not shown in the drawing, a developing roller 20MS, 20C of each of the developing devices 20M, 20C).
CS) is very small (300 μm) with respect to the photosensitive drum 15.
m), and a visible image is formed corresponding to the electrostatic line image of the photosensitive drum 15. At the time of forming a color image, the developing rotary 23 rotates every rotation of the intermediate transfer body 9, and a developing process is performed in the order of a yellow developing device 20Y, a magenta developing device 20M, a cyan developing device 20C, and then a black developing device 21B.

FIG. 1 shows a state where the yellow developing unit 20Y is positioned at a position facing the process cartridge 13 and is stationary. The yellow developing device 20Y sends the toner in the container to the coating roller 20YR by a feeding mechanism, and the developing blade 20 pressed against the outer circumference of the coating roller 20YR and the developing roller 20YS rotating clockwise.
A thin layer of toner is applied to the outer periphery of the developing roller 20YS rotated clockwise by YB, and a charge is applied to the toner (frictional charging). Photoconductor drum 15 on which latent image is formed
By applying a developing bias to the developing roller 20YS opposite to the developing roller 20, the toner is developed on the photosensitive drum 15 in accordance with the latent image. In the magenta developing device 20M and the cyan developing device 20C, toner development is performed by the same mechanism as described above.

The developing rollers of the developing units 20Y, 20M, and 20C are used for developing the respective colors provided on the main body 18 of the electrophotographic image forming apparatus when the developing units 20Y, 20M, and 20C are indexed to the developing positions and rotated. The driving member is connected to a high-voltage power supply and a drive, and a voltage is sequentially and selectively applied for each color development.

[Intermediate Transfer Body] In the intermediate transfer body 9, during the color image forming operation, the toner image on the photosensitive drum 15 visualized by the developing units 20Y, 20M and 20C is printed four times (yellow Y, magenta M and cyan C). , Each image of four colors of black B).
The intermediate transfer body 9 that has rotated clockwise in the figure in synchronization with the outer peripheral speed of the intermediate transfer member 9 and that has undergone multiple transfer is sandwiched and conveyed by the transfer roller 10 to which a voltage has been applied, whereby the intermediate transfer member 9 is transferred to the transfer material 2 Simultaneous multiple transfer of each color toner image on the body.

The intermediate transfer member 9 according to the first embodiment has a structure in which the outer periphery of an aluminum cylinder 12 is covered with an elastic layer 11 such as a medium resistance sponge or medium resistance rubber. The intermediate transfer body 9 receives a driving force from a gear (not shown) which is rotatably supported and integrally fixed, and rotates.

[Cleaning Means] The cleaning blade 16 is integrally incorporated into the above-described process cartridge 13 so as to be in pressure contact with the generatrix of the photosensitive drum 15, and the toner visualized on the photosensitive drum 15 by the developing means is removed. After being transferred to the intermediate transfer member 9, the toner remaining on the photosensitive drum 15 is scraped off and cleaned.
4 The amount of waste toner stored in the container 14 does not fill the container 14 earlier than the life of the photosensitive drum 15, and therefore, the cleaning container 14 is simultaneously replaced when the life of the photosensitive drum 15 is replaced. .

When an arbitrary point on the outer periphery of the illustrated intermediate transfer body 9 reaches the position shown in FIG. S, the photosensitive drum 15 whose surface has been uniformly charged by the charging means 17 is subjected to laser exposure at the position shown in FIG. An image is formed. The distance from the exposure position E of the photoconductor drum 15 to the first transfer position T1, which is a contact portion with the intermediate transfer member 9 counterclockwise, and the distance from the illustrated S point of the intermediate transfer member 9 to the first transfer position T1 are: After the lapse of time, the point E at the start of writing the image and the point S on the intermediate transfer member 9 are equal.
At the first transfer position T1. That is, an image is formed counterclockwise with respect to the intermediate transfer member 9 with the point S as a tip.

1: Formation of Yellow Image Laser irradiation of the yellow image is performed by the scanner unit 30 to form a yellow latent image on the photosensitive drum 15.
Simultaneously with the formation of the latent image, the yellow developing device 20Y is driven to apply a voltage having the same polarity and substantially the same potential as the charging polarity of the photoconductor drum 15 so that yellow toner adheres to the latent image on the photoconductor drum 15, and the yellow image is formed. Perform development. At the same time, the yellow toner image on the photosensitive drum 15 is primarily transferred to the outer periphery of the intermediate transfer member 9 at a first transfer position T1 slightly downstream of the developing section. At this time, a voltage having a polarity opposite to that of the yellow toner is applied to the intermediate transfer member 9 to perform primary transfer.

When the image to be formed is, for example, A3 size of Japanese Industrial Standard paper, L1 from the outer peripheral point S of the intermediate transfer member 9
When the transfer of the yellow toner to the intermediate transfer member 9 is completed, that is, the point L1 is at the first transfer position T1. , The developing rotary 23 rotates clockwise, and the next magenta developing device 20M rotates and is positioned at a position facing the photosensitive drum 15.

2: Formation of Magenta Image Next, when one point on the outer periphery of the intermediate transfer member 9 (the leading end of the yellow image) makes a circuit and reaches the position of the point S in the drawing, the scanner unit 30 similarly applies laser irradiation of the magenta image. The magenta toner image is developed on the latent image on the photosensitive drum 15 in the same manner as in the case of yellow, and the magenta toner image on the photosensitive drum 15 is similarly transferred onto the intermediate transfer body 9 at the first transfer position T1. . When the transfer of the magenta toner to the intermediate transfer member 9 is completed, that is, when the point L1 has passed the first transfer position T1, the developing rotary 23 rotates clockwise, and the next cyan developing device 20C rotates, and the photosensitive drum 20C rotates. 15 are positioned.

3: Formation of Cyan Image Next, when one point on the outer periphery of the intermediate transfer member 9 (the leading end of the yellow and magenta images) makes another round and reaches the position of the point S in the drawing, the scanner unit 30 similarly forms the cyan image. Laser irradiation is performed, and the photosensitive drum 15
A cyan toner image is developed on the upper latent image, and the photosensitive drum 1
5 is transferred onto the intermediate transfer member 9 at the first transfer position T1 so as to overlap the yellow and magenta toner images. When the transfer of the cyan toner to the intermediate transfer member 9 is completed, that is, when the point L1 has passed the first transfer position T1, the developing rotary 23 rotates clockwise by 60 degrees and the photosensitive drum 1
5, color developing units 20Y, 20M, 2
There is no 0C.

4: Formation of Black Image Next, when one point on the outer periphery of the intermediate transfer member 9 (the leading end of the yellow / magenta / cyan image) makes another round and reaches the position shown in FIG. Then, the black toner is developed by the black developing unit 21B, and the black toner image on the photosensitive drum 15 is further transferred onto the intermediate transfer body 9 at the first transfer position T1.

As described above, the latent image formation and development and the toner transfer to the intermediate transfer member 9 are sequentially performed four times in the order of yellow, magenta, cyan, and black.
A full-color image composed of four types of toner, magenta, cyan, and black, is formed.

Before the transfer of the black toner image to the intermediate transfer member 9 is completed, that is, the image transfer point S of the intermediate transfer member 9 on which the first transfer of the black toner image is completed and the full color image is formed is the second transfer. Before reaching the section T2, the transfer material 2 that has been waiting by the above-described registration roller 8 is started to be conveyed at a proper timing. At the time of forming each color image on the intermediate transfer body 9 for the four times, the transfer roller 10 which waits downward and is not in contact with the intermediate transfer body 9 is simultaneously moved upward by a cam (not shown) to transfer the transfer material 2. At the second transfer portion T2 of the intermediate transfer member 9 and simultaneously applying a bias having a characteristic opposite to that of the toner to the transfer roller 10 to simultaneously transfer four colors of the full-color image on the intermediate transfer member 9 to the transfer material 2 at once. .
The transfer material 2 that has passed through the second transfer portion T2 is separated from the intermediate transfer member 9 and is conveyed to the fixing portion 25, where the toner is fixed. The image is discharged onto the discharge unit 37 with the image surface facing downward, and the image forming operation ends.

[Detailed Description of Developing Means] Next, the developing means 20 of the present invention will be described in detail with reference to FIGS.

First, the mounting and positioning of the developing units 20Y, 20M and 20C on the developing rotary 23 will be described.

The developing rotary 23 has three developing units 2
In order to support 0Y, 20M, and 20C, three stays 23A are radially extended from the center shaft 22 radially outward in the circumferential direction at three positions, as shown in FIG. Developing device support portion 23 for supporting any one of the developing devices 20Y, 20M, and 20C in the portion.
B and 23C are erected at both ends in the longitudinal direction. FIG. 5 shows one of the three stays 23A in the drawing. The lower right is the outer peripheral portion of the developing rotary 23, and the upper left is the center shaft 22 side. Developing device support portion 23B,
The developing device 20 is inserted into the round hole 23D and the long hole 23E on the developing device 23C.
Y, 20M, 20C fixed cylindrical swing center shaft 44
A, 44B (refer to FIG. 3). Developing devices 20Y, 20M, 2
The state where 0C is mounted is as shown in the perspective view of FIG. Incidentally, in FIG. 3, the developing device 20Y is mounted on one of the developing device support portions 23B and 23C of the developing rotary 23 and is in a state of developing. However, the developing device 20Y is connected to the electrophotographic image forming apparatus main body 18, that is, the developing rotary 23.
The developing rotary 23 is rotated to a developing position as shown in FIG. 3, that is, a position other than the position facing the photoconductor drum 15, and is carried out there.

The developing devices 20Y and 20Y in the first embodiment
0M and 20C can be attached to and detached from the electrophotographic image forming apparatus main body 18 from the front of the machine, that is, the developing units 20Y, 20M, and 20C.
20C is adapted to be slid in the longitudinal direction and detached, and the developing devices 20Y, 20M,
20C is inserted and attached to the developing rotary 23. At this time, the central axes 44A, 4A of the developing devices 20Y, 20M, 20C
A guide (not shown) for inserting (fitting) the holes 4D into the holes 23D and 23E is provided on the developing rotary 23, and the developing devices 20Y, 20M and 20C are mounted on the developing rotary 23 along the guides. Then, after the mounting, it is fixed by a stopper (not shown) for preventing it from coming off in the thrust direction. When the developing devices 20Y, 20M, and 20C are mounted on the developing rotary 23, the developing devices 20 fitted in the holes 23D and 23E are used.
Centering on the central axes 44A, 44B of Y, 20M, 20C,
Each of the developing devices 20Y, 20M, and 20C is swingable.

The developing rotary 23 is indexed at an angle of 120 degrees around the center axis 22 and the angle
It is connected to a rotation indexing device (not shown) so that one of the degrees can be rotated by 60 degrees.

Next, the operation in which the developing rotary 23 to which the developing devices 20Y, 20M, and 20C are mounted for index rotation to perform development will be described.

In the first embodiment, the developing rotary 23
Is in the direction of arrow γ shown in FIG. When an instruction (signal) for developing is issued, the developing rotary 23 rotates so that one of the target developing units 20Y, 20M, and 20C comes to a developing position facing the photosensitive drum 15. In this case, the developing rotary 23 is provided with a sensor (not shown) that can detect the indexing position, so that one of the developing devices 20Y, 20M, and 20C can be accurately moved and stopped at a predetermined position.

FIG. 6 shows a photosensitive drum 1, a developing roller 20YS (20MS, 20CS) and a center shaft 2 in a developed state.
It is a front view which shows the relationship of 2. As shown in this figure, at the developing position, the centers 15C, 20YS-C, 22
C is located on the same straight line 42. The developing roller 20YS is provided on the electrophotographic image forming apparatus main body 18 side.
The center 45C of the drive gear 45 for driving (20MS, 20CS) is also located on the straight line 42. Developing unit 20Y (2
0M, 20C) includes a developing roller 20YS (20MS, 20MS).
20CS), and a developing roller gear 41 (see FIG. 3) exists on the same axis as that of the driving gear 45. An external driving force is input to the driving gear 45, and rotation is transmitted from the driving gear 45 to the developing roller gear 41 meshing with the driving gear 45. Developing device 20Y (20M, 2
0C) is driven. That is,
When the developing device 20Y (20M, 20C) comes to the developing position, the driving gear 45 on the electrophotographic image forming apparatus main body 18 side.
Then, the developing roller gear 41 meshes, and one of the developing devices 20Y (20M, 20C) is driven by the driving gear 45.

Therefore, the center 45C of the driving gear 45 is
The photosensitive drum 15 and the developing roller 20YS (20MS, 2
0CS), each center 15C, 20YS- of the center shaft 22
When the developing rotary 23 is stopped at a regular position due to being on the aforementioned straight line 42 connecting C and 22C, the distance between the axis of the developing roller gear 41 and the driving gear 45 of the apparatus main body 18 becomes the shortest. Since the stop error is in the direction in which the axial distance between the developing roller gear 41 and the drive gear 45 becomes longer, an accident such as breakage does not occur. Incidentally, the arrow α1 shown in FIG. 6 is the photosensitive drum 15, the arrow α2 is the drive gear 45, and the arrow β is the developing roller 2.
0YS (20MS, 20CS) and developing roller gear 41
Represents the rotation direction.

As shown in FIG. 3, the developing roller 20YS (2
0MS, 20CS) on both sides of the developing roller 20YS (2
(0MS, 20CS), and a roller 40 is attached, which has a larger radius than the developing gap. When one of the developing units 20Y, 20M, and 20C comes to the developing position, the roller 40YS abuts against the surface of the photosensitive drum 15 and the developing roller 20YS (20MS, 20MS) contacts the photosensitive drum 15.
20CS) is determined. As shown in FIGS. 3 and 4, the developing device 20Y (20M, 20C) is pressed against the photosensitive drum 15 by a force F by a compression coil spring 23a. To perform development, the developing roller 20Y
It is very important to keep the clearance between the S (20MS, 20CS) and the surface of the photoconductor drum 15 constant. However, with this configuration, the clearance between the two is limited only by the dimensional accuracy of the roller 40. Because it is determined, the configuration is very easy to manage.

At the developing position, the developing device 20Y (20M, 20M)
In order to ensure that the abutting roller 40 of C) abuts on the surface of the photoreceptor drum 15, at a location other than the developing position,
The developing unit 20Y (20M, 20C) is set at a position (in the direction of arrow δ1 in FIG. 6) where the developing unit 20Y (20M, 20C) is slightly swung into the photosensitive drum 15 side about the swing center L. The penetration amount is about 1 mm. For this reason, the developing rotary 23 is provided in a direction other than the developing position in the direction of arrow δ1 in FIG.
A stopper (not shown) is provided so that the roller 40 stops at a position where the roller 40 has entered by about 1 mm (restricts swinging), the developing rotary 23 rotates, and the developing device 20Y (20
M, 20C) comes to the developing position,
Abuts on the surface of the photosensitive drum 15, the developing device 20Y (20M, 20C) swings about the swing center L in the direction of arrow δ2 in FIG. 6, and the position is determined.

Further, the developing rotary 23 rotates, and the developing roller 20YS (2) of the developing device 20Y (20M, 20C) is rotated.
0MS, 20CS) comes in contact with the photosensitive drum 15, and the swing center L, which is the axis of the swing center axes 44A, 44B of the developing units 20Y (20M, 20C) (see FIG. 6).
However, as in the present embodiment, with respect to the rotation direction of the developing rotary 23, the developing roller 20YS (20MS, 20CS)
When the developing roller 20YS (20MS, 20CS) is in a more advanced position, the developing roller 20YS (20MS, 20CS) can smoothly come into contact with the photosensitive drum 15 (it is easy to escape from the photosensitive drum 15). With respect to the rotation direction of the developing rotary 23, the developing roller 20YS is
If (20MS, 20CS) is at the preceding position, the contact of the developing roller 20YS (20MS, 20CS) with the photoconductor drum 15 may be more likely to penetrate the photoconductor drum 15; There is a possibility that a problem may occur with respect to the rotation of 23 or the like.

The developing roller 20YS (20MS, 20C
S) comes into contact with the photosensitive drum 15, the developing roller 20
It is necessary that both the abutting rollers 40 provided at both ends of the YS (20MS, 20CS) abut. However, the holes 23D, 23
In the case where both E are perfect circles and the swing center L (see FIG. 3) connecting the centers thereof is not parallel to the axis of the photosensitive drum 15, both the butting rollers 40 are photosensitive members. It cannot contact the drum 15. For this reason, in the first embodiment, the hole 23E into which the positioning shaft 44B for swingably supporting the non-driving side of the developing device 20Y (20M, 20C) is fitted as shown in FIG. 15 center 15C and the developing roller center 20YS-C (MS-C,
CS-C), and is a long hole parallel to the straight line 42 connecting the developing device 20Y (20M, 20C), and a spring contracted between the developing rotary 23 and the developing device 20Y (20M, 20C), for example, a compression coil spring 23a. And the two pushing rollers 40 can contact the surface of the photosensitive drum 15. The spring 23a may be a leaf spring. Incidentally, the hole 23D in which the positioning shaft 44A on the driving side enters needs to be a perfect circle in order to guarantee the engagement accuracy between the developing roller gear 41 and the driving gear 45.

Finally, based on FIG. 6, the developing device 20Y
The relationship between the mechanical relationship when (20M, 20C) is driven and the swing center L will be described.

As shown in FIG. 6, the developing unit 20Y receives the spring force F about the swing center L and faces the photosensitive drum 15, and the developing roller 20YS (20MS, 2MS) is driven by the drive gear 45.
0CS) and the developing roller gear 41 coaxially rotates, and the developing roller 20YS (20MS, 20CS) rotates.

As shown in FIG. 6, in the state of development, the driving gear 45 of the electrophotographic image forming apparatus main body 18 causes
Developing roller gear 41 of developing unit 20Y (20M, 20C)
Is driven, a force f in the direction of the action line 47 of the gear meshing through the pitch point P acts on the tooth surface. In the case of an involute gear, this action line 47 is straight and immovable. Here, θ shown in the drawing is an angle formed between the tangent line 46 of the pitch circle and the action line 47 at the pitch point of the gears 41 and 45, and represents the engagement pressure angle between the developing roller gear 41 and the drive gear 45. When a force f acts on the tooth surface,
Naturally, the load f also acts on the developing roller gear 41 in the same direction. This load f is equal to the developing roller center 20YS-
It is decomposed into a normal load fr in a direction connecting C (20MS-C, 20CS-C) and the swing center L, and a tangential load ft perpendicular to the normal load fr. For this reason, the component force of ft as the rotational force with respect to the swing center L and the developing roller center 20YS-
Since the rotational force equal to the product of the distance between C and the swing center L is acting, the developing device 20Y (20M, 20C) uses the arrow δ
The force in the direction of 1, i.e., the direction in which the photosensitive drum 15 contacts, acts in the same direction as the direction in which the spring force F acts. Since it is small, development can be performed in a stable state.

Further, in order to keep the roller 40 and the photosensitive drum 15 in stable contact with each other in the developing state, a certain amount of force is required. Can be For this reason, the spring force F can be reduced by an amount corresponding to the force based on the meshing of the gears, so that the shock when the developing rotary 23 rotates and abuts the roller 40 against the photosensitive drum 15 can be reduced. it can.

Further, the photosensitive drum center 15 described above
C positioning and center shaft 22 of developing rotary 23
Are performed by the same member, that is, the side plate, and the relative positional accuracy of the two is guaranteed with high accuracy. That is, since the center shaft 22 of the developing rotary 23 of the developing unit 20 is provided on a side plate (not shown) on which the mounting unit (not shown) of the process cartridge 13 is provided.
Each developing device 20Y, 20M, 2
0C is positioned with high precision.

In the first embodiment, the photosensitive drum 1
5 is incorporated in the process cartridge 13, but when the photosensitive drum 15 is directly attached to the electrophotographic image forming apparatus main body 18 without taking the configuration of the process cartridge 13, the photosensitive drum 15 and the developing device By attaching the means 20 to the same side plate, the developing units 20Y, 20M, 20
The position of C can be accurately determined.

In the first embodiment, the developing means 20 has the developing units 20Y, 20M, and 20C arranged at positions where the circles are equally arranged. However, it is not always necessary to arrange the developing units 20Y, 20M and 20C at positions where the circles are evenly arranged.
For example, the developing units 20Y, 20M, and 20 are spaced at an angle of 90 degrees from each other at an angle of 180 degrees around the center axis 22.
The present invention can be realized even when C is arranged in a fan shape.

Further, the drive gear 45 is characterized in that it is located outside the circular locus of the swing center L about the center shaft 22 as shown in the dynamic relationship of the present configuration. With the conventional configuration located inside, the center of the center shaft 22 is 3 to 10 c.
Since m is a dead space, the size of the apparatus main body is increased. However, this configuration can achieve a space saving of 30 to 314 cm ² in cross section even if a developing device having the same capacity is arranged.

Next, details of the gears for driving the developing units 20Y, 20M and 20C will be described. Developing units 20Y, 20
M, 20C to drive the developing roller 20YS (20
(MS, 20CS), a developing roller gear 41 is mounted coaxially. The tooth width is a torsion angle in which the overlapping mesh ratio between the developing roller gear 41 and the drive gear 45 is 1 to 1.5 or more. For example, in this embodiment, the module of the drive gear 45 of the developing roller gear 41 is 0.8, and the number of teeth is 24 and 23, respectively (when the helix angle is 20 °), the tooth width is designed to be 8 to 19 mm.

[Process Cartridge Attachment / Removal Operation] FIG. 7
FIG. 3 is a perspective view of the image forming apparatus main body 18 in which an upper cover, a right cover, a left cover, and a front cover that can be opened and closed also serve as a discharge unit 37 (not shown). When the image forming operation is completed, the developing roller 21BS of the black developing device 21B is located at a position separated from the photosensitive drum 15, and
Indicates that any one of the developing devices 20Y and 20
The developing rollers 20YS, MS, and CS of M and 20C are also located at intermediate positions not opposed to the photosensitive drum 15. Then, as shown in FIG. 7, the process cartridge 13 can be pulled out and taken out to the front side in the longitudinal direction when viewed from the user. At this time, the process cartridge mounting portion 18a of the image forming apparatus main body 18 and the mounting portion 13a of the process cartridge 13 are fitted, and the process cartridge mounting portion 1
8a is oriented in the longitudinal direction, so that the image forming apparatus main body 1
The process cartridge 13 can be attached and detached without touching other members in the cartridge 8.

[Detailed Description of Cleaning Means] In the present invention, the cleaning means constitutes the process cartridge 13 (drum unit). As shown in FIG. 8, the process cartridge 13 includes a primary charging unit 17, a cleaning blade 16, and a cleaning blade 16.
The cleaning means having the cleaning container 14 for storing the residual toner on the photosensitive drum 15 removed as a waste toner and the electrophotographic photosensitive member provided as the photosensitive drum 15 are integrated into a cartridge using the cleaning container 14. The cartridge is detachable from the image forming apparatus main body 18. However, there is a mode of each combination with the primary charging unit 17 and the developing unit.

The cleaning blade 16 has an elastic blade 16a made of rubber or the like pressed in contact with the tip of the photosensitive drum 15 in a direction of movement of the peripheral surface of the photosensitive drum 15 at an angle so as to be vulcanized or bonded to the tip of the support plate 16b. It is fixed at.
In FIG. 8, the supporting plate 16b has the photosensitive drum 1 at the tip end.
5 supported to be biased toward the surface. For example, the supporting metal plate 16b is supported on the cleaning container 14 by a pivot (not shown) whose root side is orthogonal to the plane of FIG. 8, and is urged to rotate clockwise around the pivot by a spring member (not shown). .

With respect to the cleaning blade 16,
Regarding the moving direction of the peripheral surface of the drum-shaped photosensitive drum 15,
The primary charging means 17 is provided on the downstream side. The primary charging means 17 in this embodiment is a charging roller 17a, and a core shaft 17b protruding from both ends thereof is rotatably supported by a bearing (not shown). The bearing is movable in the radial direction of the photosensitive drum 15 so that the cleaning container 14 is movable. It is supported by. (The supporting method is not shown). The charging roller 17a is pressed against the photosensitive drum 15 by a compression coil spring 17c which is contracted in the radial direction of the photosensitive drum 15 between the bearing and the cleaning container 14.

The charging roller 17 a is, for example, a rubber member that has been subjected to a conductive process, and applies a voltage for uniform charging to the photosensitive drum 15 while being driven and rotated by the photosensitive drum 15.

The cleaning container 14 has substantially the same length as the photosensitive drum 15 in a longitudinal direction perpendicular to the conveying direction of the recording medium 2 in the cross section shown in the drawing, and has a container shape as a whole.
End plates 14j are provided at both ends in the longitudinal direction, and the end plate 14j side is extended in an arm shape to form a drum support portion 14a. The photosensitive drum 15 is fixed to a drum shaft 15a rotatably supported by the drum support 14a.

The squeeze sheet 24 faces the photosensitive drum 15 with its leading end facing the cleaning blade 16.
And is fixed to the cleaning container 14. Cleaning blade 16 tip and squeeze sheet 24
Between the leading ends is an external opening of the cleaning container 14 that opens toward the photosensitive drum 15. When the toner remaining on the photosensitive drum 15 reaches the squeeze sheet 24 along with the movement of the peripheral surface of the photosensitive drum 15 in the direction indicated by the arrow a in the drawing, it passes through the squeeze sheet 24 and the photosensitive drum 15, but wastes in the cleaning container 14. The squeeze sheet 24 is set so as to have a pressing force and an angle so that toner does not leak.

The back of the cleaning blade 16 and the squeeze sheet 24 constitute a toner collecting section. A space called a cleaning chamber 14A is formed in the back.
Partition walls 54a and 54b are provided on the back of the cleaning blade 16 and the squeeze sheet 24 at an interval therefrom,
Cleaning blade 16, squeeze sheet 24, partition walls 54a, 54b, top plate 14d of cleaning container 14.
, A part of the lower plate 14e, and a part of the end plate 14j form a cleaning chamber 14A. Upper partition wall 54
b has an arc-shaped portion 54b1 at the lower end, and the lower partition wall 5
Reference numeral 4a is an arc having a central angle close to 90 degrees and is in contact with the lower plate 14e. An opening 54c is provided between the partition walls 54a and 54b over substantially the entire area in the longitudinal direction. A waste toner accumulation chamber 14B is provided adjacent to the cleaning chamber 14 with the partition walls 54a and 54b therebetween. The upper edge of the lower partition wall 54a, that is, the lower edge of the opening 54c,
It is located higher than the lower plate 14e in the waste toner accumulation chamber 14B.

Next, the shape of the cleaning container 14 will be described. The cleaning container 14 has a flat top plate 14d and a lower plate 14e that are substantially parallel to each other.
4f is a substantially vertical flat plate. A hanging wall 14g is hung from the back of the supporting metal plate 16b of the cleaning blade 16. Further, a front wall 14h covering the primary charging means 17 protrudes from an end of the top plate 14d and faces the photosensitive drum 15 with a gap from the photosensitive drum 15. Both ends in the longitudinal direction of the cleaning container 14 are end plates 14j substantially parallel to the paper surface of FIG. The top plate 14d is provided with a ridge-shaped mounting portion 14i having a crank-shaped cross section symmetrically on the top plate 14d in the entire longitudinal direction orthogonal to the plane of FIG. The process cartridge mounting portion 18 that is linearly guided on the image forming apparatus main body 18 so as to face the left and right so that the mounting portion 14i of the protrusion is fitted.
a is provided.

The cleaning chamber 14A is provided with waste toner feeding means for sending the waste toner in the cleaning chamber 14A to the waste toner accumulation chamber 14B through the opening 54c. The waste toner feeding means in this embodiment is feed blades 19 attached to a rotating shaft 19a rotatably supported by end plates 14j on both sides of the cleaning chamber 14A.
The feed blade 19 has a length in the longitudinal direction to which the rotating shaft 19a is fixed, and a flexible sheet 19b is attached to the entire length of a sheet metal boss having a key-shaped cross section. This flexible sheet 1
9b has a thickness of about 50 μm.
b is in contact with the arc-shaped partition 54b1 centered on the rotary shaft 19a provided at the lower end of the lower partition 14e and the arc-shaped partition wall 54a centered on the rotary shaft 19a and the hanging partition wall 54b. The tip is bent. This arc-shaped portion 54
The b1 and the lower partition wall 54a are arc-shaped surfaces having the same center and the same radius as the center of the rotating shaft 19a.

When the process cartridge 13 is attached to the image forming apparatus main body 18, the lower partition wall 54a is
The rotation axis 19a of the feed blade 19 is located at a position slightly higher than the upper edge of the feed sheet 19, and when the leading end of the flexible sheet 19b rotates to the lower edge of the opening 54c, the flexible sheet 19b The feed blade 19 is inclined so that the side is downward.
The upper waste toner easily moves to the waste toner accumulation chamber 14B through the opening 54c. In this case, a centrifugal force also acts on the waste toner on the feed blade 19, so that the waste toner can be more easily given a momentum toward the toner accumulation chamber 14B.

Next, backflow preventing means for preventing backflow of waste toner from the waste toner accumulation chamber 14B to the cleaning chamber 14A through the opening 54c will be described. A non-return valve 57 having a valve seat at the edge of the opening 54c on the waste toner accumulation chamber 14B side is fixed to the upper edge side of the opening 54c of the cleaning container 14.
It is provided to be able to swing freely. The check valve 57 keeps the opening 54c closed by gravity or a pressure spring (not shown). And if you want to close the valve by gravity,
A stopper (not shown) is provided to prevent the check ring 57 from opening beyond the position shown by the dotted line in FIG. In addition, the check ring 57 fixes one end of an elastic body such as a flexible sheet to the upper edge of the opening 54c on the side of the waste toner accumulation chamber 14B to apply a biasing force in the valve closing direction to the check ring 57 itself. You may have it. However, the check valve 57 is set to be easily opened by the pressure of the waste toner powder carried to the opening 54c by the feed blade 19. When the flexible sheet 19b of the feed blade 19 is in contact with the check valve 57, the check valve 57 is pressed against the pressure of the waste toner powder and the flexible sheet 19b.
When the process cartridge 13 is removed from the image forming apparatus main body 18 in a state of being pushed open by the elasticity, the feed blade 19 separated from the driving member on the image forming apparatus main body 18 side by the urging force to close the check valve 57. The urging force of the check valve 57 is determined so that the check valve 57 rotates and the check valve 57 can close the opening 54c.

The operation of the cleaning means of the process cartridge 13 having the above configuration will be described. Photoconductor drum 1
5 rotates in the direction of arrow a in FIG.
The residual toner after the above transfer passes through the squeeze sheet 24 and the photosensitive drum 15, reaches the cleaning blade 16, is scraped off, is guided to the squeeze sheet 24, and collects on the lower plate 14e of the cleaning chamber 14A to become waste toner. Deposit. The rotating shaft 19a of the feed blade 19 disposed in the cleaning chamber 14A is rotatably supported by an end plate 14j in the cleaning chamber 14A of the cleaning container 14. When the process cartridge 13 is mounted on the image forming apparatus main body 18, an image is formed. The feed blade 19 is connected to a driving member (not shown) on the forming apparatus main body 18 side, and rotates in the direction of the arrow b in the drawing to feed the waste toner accumulated in the cleaning chamber 14A to the rear of the container. That is, the flexible sheet 19b is sent to the rear of the container so as to sweep the waste toner on the lower plate 14e, and then the arc-shaped partition wall 54a on the lower side toward the opening 54c higher than the lower plate 14e. Lift along. When approaching the opening 54c, the check valve 57 is moved by the pressure of the waste toner powder on the front side in the traveling direction of the flexible sheet 19b.
8 rotates counterclockwise in the direction of arrow c in the figure, and the waste toner falls into the waste toner accumulation chamber 14B, or when there is a large amount of waste toner in the chamber 14B, the waste toner in the chamber 14B It is pushed in. When passing the lower edge of the opening 54c at the tip of the flexible sheet 19b,
The flexible sheet 1 is formed by the elasticity and centrifugal force of the flexible sheet 19b.
9b assists the operation of sending out the waste toner so as to restore the waste toner to a linear shape and to fly the waste toner to the waste toner accumulation chamber 14B.

Then, the flexible sheet 19b that has passed through the opening 54c is connected to the arc-shaped portion 54b1 of the upper partition wall 54b.
, And then passes through the arc-shaped portion 54b1 to restore its shape, rotate in the space in the cleaning chamber 14A, and again contact and bend with the lower plate 14e, and then arc-shaped partition. The waste toner is scraped up on the wall 54a toward the opening 54c. In the above, after the flexible sheet 19b sends out the waste toner through the opening 54c, the check ring 57 rotates around the check valve support 58 in the clockwise direction opposite to the arrow c in the drawing. The opening 54c is closed.

When the process cartridge 13 is pulled out from the process cartridge mounting portion of the image forming apparatus main body 18 and removed, and the posture is changed, for example, when the cleaning blade 16 side is turned down, the waste toner accumulation chamber 1
Although the waste toner in 4B is biased toward the opening 54c side, the waste toner cannot proceed to the cleaning chamber 14A because of the check valve 57.

At the end of image formation, the flexible sheet 19b of the feed blade 19 pushes the check valve 57 to push the check valve 5
Even when the process cartridge 13 is detached from the image forming apparatus main body 18 with the opening 54c opened, the feed blade 19 that has come off the driving member of the image forming apparatus main body 18
Can easily rotate, and the check valve 57 closes the opening 54c by the urging pressure of the check valve 57. Thus, even if the user handles the process cartridge 13 by detaching it from the image forming apparatus main body 18, the waste toner remains in the waste toner accumulation chamber 14 of the cleaning container 14.
Without entering the cleaning chamber 14A from the inside of B, the vicinity of the external opening of the cleaning chamber 14A on the photosensitive drum 15 side can always be maintained in a state where there is no powder pressure with no waste toner. Thereby, appropriate cleaning performance can be guaranteed during the life of the photosensitive drum 15.

Then, in the cleaning chamber 14A, the lower plate 1
4e, an arc-shaped partition wall 54a is provided, and the flexible sheet 19b of the feed blade 19 moves while being pressed against the lower plate 14e and the partition wall 54a.
Almost all of the waste toner is sent to the waste toner accumulation chamber 14B, so that the waste toner does not accumulate in the cleaning chamber 14A, and good cleaning performance is maintained.

[Structure of Photosensitive Drum] Photosensitive Drum 15
A flange 300 having a drum shaft 15a is press-fitted into a hollow cylindrical cylinder 15b (see FIG. 11) of aluminum Al (ell), and the drum shaft 15a is rotatably supported by a drum support portion 14a of the cleaning container 14. ing. One of the drum shafts 15a is fitted into a coupling 201 (see FIG. 9) protruding from the rear plate of the apparatus main body 18 and rotated. It is preferable that there is no difference between the diameter of the shaft on the photosensitive drum 15 side and the diameter of the coupling hole at the end of the drum drive shaft 201 in order to smoothly rotate the photosensitive drum 15.
However, a fitting gap of 10 to 50 μm is provided in consideration of the detachability of the process cartridge 13. The photoconductor drum 15 has the developing units 20Y, 20M, 20 described above.
C, the cleaning blade 16 and the intermediate transfer member 9 are in contact with each other, so that the photosensitive drum 15 receives an external force.
Further, when the toner on the intermediate transfer member 9 is transferred to the recording medium 2, the transfer belt comes into contact with the intermediate transfer member 9, so that the speed unevenness of the belt is transmitted to the intermediate transfer member 9, and the rotation unevenness is transmitted to the photosensitive drum 15.

In order to reduce these, usually, an inertia body is added on the drum drive shaft 201 of the apparatus main body 18 shown in FIG. There is also a method of putting a weight in the photosensitive drum 15. However, when the photosensitive drum 15 is configured as a cartridge, since a drive transmission portion of the photosensitive drum 15 is provided with a coupling, a much larger inertial body must be attached to the photosensitive drum 15 than a component without the coupling. Specifically, the inertial mass is 100 kgf-cm ² . This inertial mass is a full-color case of 600 dpi, and is not limited to a machine with a low resolution or a black and white machine with a low frequency of outputting a low-density image. Accordingly, as the dpi and color become higher, the above-mentioned inertial mass must be increased, and the drum drive shaft 201 bends, and the exposure position of the laser shifts, so that the parallelism of the image cannot be maintained. .

When an inertial body is inserted into the drum cylinder, it can directly act on the photosensitive drum 15 which is displaced. Therefore, if an inertial mass of 20 kgf-cm ² is inserted, a shock due to disturbance does not appear. However 60m in diameter
20 kg even if the cylinder of the photosensitive drum 15
In order to accommodate the inertial body of f-cm ² , a mass of about 6 kgf must be included. Therefore, there arises a problem such as how to take measures when there is a possibility that the weight of the process cartridge 13 increases and the process cartridge 13 may fall on the user's foot.

In order to suppress the shock and rotation unevenness of the photosensitive drum 15 due to disturbance without greatly increasing the mass, as shown in FIG. 10, a drum shaft 15a in a cylinder 15b is connected to a drum shaft 15a via a viscoelastic body 202. It is effective to attach the mass body 203. More specifically, the viscoelastic body 202 is made of a rubber material (nitrile rubber, Nosorex (trade name), silicon rubber) or a malt plain material.
In general, iron, stainless steel, and brass are used.
This mass body 203 is unitized to a boss 204 via a viscoelastic body 202 as shown in FIG. As a mounting method, as shown in FIG. 11, a boss 204 supporting a mass body (through a viscoelastic member 202) 203 is press-fitted or fitted to the drum shaft 15 a and fixed with a set screw 302. By attaching the mass body 203 to the drum shaft 15a, the amount of imbalance of the mass body 203 attached via the viscoelastic body 202 can be reduced as much as possible. In FIG. 10, the left and right mass bodies 203 are fixed to the drum shaft 15a via the viscoelastic body 202 having the same viscoelastic coefficient at the left and right target positions, and in FIG. The mass body 203 attached to the drive shaft 15a on the right side (in FIG. 11) is the mass body 203 attached to the drive shaft 15a on the non-drive side (left side in FIG. 11).
Greater than. In order to match the vibration-proof frequency, the weight and the moment of inertia of the mass body 203 and the viscoelastic body coefficient of the viscoelastic body 202 may be changed. Specifically, the rubber hardness and material are changed to change the viscoelastic coefficient. Also,
In order to dampen a plurality of frequencies, a plurality of mass bodies (through a viscoelastic member) tuned to the frequency to be damped may be attached to the drum shaft 15a. Therefore, the frequency to be damped depends on the machine, but any frequency can be damped simply by replacing the damping member.

FIG. 12 is a diagram modeling this embodiment. The drum cylinder 15b is subdivided into small masses _{M 1, M 2 ... M n} , considering subdividing the mass body 203 in the minute masses _{m 1, m 2 ... m n} , vibration of the vibration system, respectively microelements M ₁ of, M ₂ ... M _n and m _1, m ₂ ... m
_n is the spring element K in the rubber plate (viscoelastic body 202)
_1, K ₂ ... are regarded as coupled vibration when linked by K _n and the damper element _{C 1, C 2 ... C n} . The vibration system spring element k ₁ be external vibration is applied to, k ₂ ... k _n and and damper elements C _1, C ₂ ... vibrated by C _n is attenuated each minute masses are vibration isolation from each other.

10 and 11 are mainly used when the photosensitive drum 15 is displaced in the horizontal and vertical directions, and FIG. 11 is used in which the mass body 203 on the side more affected by the shaft coupling is made larger. . When the rotation unevenness component is large, the type shown in FIG. 10 in which the vibration moment of the mass body 203 is increased is used. Tuning is performed by changing the hardness, mass of the rubber, and the weight of the mass body according to the frequency of displacement. FIG.
(A) and (b) show data before and after the present embodiment is input. FIG. 13A shows the rotation unevenness data of the photosensitive drum before the embodiment of the present invention is loaded. Development drive gear 45
7 corresponding to the meshing frequency of the gear with the developing roller gear 41
The rotation unevenness at 0 Hz is 0.2%.

Since the process speed of the embodiment of the present invention is 140 mm / s, unevenness having a pitch of 2 mm (= 140/70) was found. By applying this embodiment, the rotation unevenness at 70 Hz becomes 0.05% and the rotation unevenness disappears (see FIG. 13B).

Further, in the present embodiment, a metal is used as the viscoelastic member and the mass as the viscoelastic member. However, the present invention is not limited to this, and an adhesive tape, a sponge, or the like may be used as the viscoelastic member.

In this embodiment, a pair of viscoelastic members and a mass body are joined. However, the present invention is not limited to this, and a plurality of viscoelastic members and mass bodies may be combined to form a multilayer. Is also good.

The present embodiment is not limited to the photoreceptor, but may be applied to an intermediate transfer member and a transfer belt (the inventor, specifically, how to do this).

(Other Embodiments) FIG.
A viscoelastic body 20 fixed to the inner end face of the shaft 0 and extending in the axial direction
2 is provided with a disk-shaped mass body 203 at the tip. The viscoelastic body 202 is dotted on a ring or circumference.

FIG. 15 shows a structure in which an annular ring 205 is fixed to a cylinder 15b by press-fitting or caulking. A unitized damping member is provided with a viscoelastic body 202 on the outer circumference of an annular mass body 203 and the outer circumference thereof. Is provided with a ring 205 and vulcanized and fixed.

FIG. 16 shows that the photosensitive drum 1 is connected to the drum shaft 15a.
5, a cylinder 15b, a flange 3
00, and the drum shaft 15a is fixedly connected to each other.
In the central portion in the axial direction of 5b, the drum shaft 15a is
Boss 204, viscoelastic body 202, mass body 203 similar to 1
Is fixed by a set screw 302. The above embodiment can be used when the drum shaft 15a penetrates the photosensitive drum 15. In the case of the drum shaft 15a having a through shaft, a plurality of mass bodies may be juxtaposed via a viscoelastic body in the axial direction, and a shape that is integrally long in the axial direction is possible.

[0101]

According to the present invention, since a mass body is provided via an viscoelastic member in an electrophotographic photosensitive drum and an intermediate transfer member, an electrophotographic photosensitive drum which can smoothly rotate without particularly increasing the size of the apparatus. , An intermediate transfer member can be obtained,
In the electrophotographic image forming apparatus in which the process cartridge intermediate transfer body having the electrophotographic photosensitive drum is detachable, and the electrophotographic image forming apparatus having the electrophotographic photosensitive drum intermediate transfer body, a toner image of good image quality is supported. It is possible to obtain a recording medium.

[Brief description of the drawings]

 Each of the drawings shows an embodiment of the present invention,

FIG. 1 is a longitudinal sectional view of a color laser printer according to the present invention.

FIG. 2 is a longitudinal sectional view of the color laser printer according to the present invention, showing an image forming operation.

FIG. 3 is a perspective view showing a relationship between a developing device, a developing rotary, and a photosensitive drum.

FIG. 4 is a side view illustrating a relationship between a developing device, a developing rotary, and a photosensitive drum.

FIG. 5 is a perspective view showing a part of a developing rotary.

FIG. 6 is a side view showing a mechanical relationship among a developing device, a developing rotary, and a photosensitive drum.

FIG. 7 is a perspective view of an image forming apparatus main body.

FIG. 8 is a longitudinal sectional view of the process cartridge.

FIG. 9 is a perspective view illustrating a driving unit of the electrophotographic photosensitive drum.

FIG. 10 is a perspective view of the electrophotographic photosensitive drum according to the first embodiment.

FIG. 11 is a vertical sectional view of the electrophotographic photosensitive drum according to the first embodiment.

FIG. 12 is a model using a viscoelastic body.

FIG. 13A is a diagram showing vibration data according to a conventional example, and FIG. 13B is a diagram showing vibration data according to an embodiment of the present invention.

FIG. 14 is a longitudinal sectional view of an electrophotographic photosensitive drum according to another embodiment.

FIG. 15 is a longitudinal sectional view of an electrophotographic photosensitive drum according to another embodiment.

FIG. 16 is a longitudinal sectional view of an electrophotographic photosensitive drum according to another embodiment.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 paper feed cassette 2 transfer material (recording medium) 3 paper feed roller 4 feed roller 5 retard roller 6 paper feed guide 7 transport roller 8 registration roller 9 intermediate transfer body 10 transfer roller 11 ... Elastic layer 12 ... Aluminum cylinder 13 ... Process cartridge 13a ... Mounting part 14 ... Cleaning container 14a ... Drum support part 14
c ... opening 14d ... top plate 14e ... lower plate 14f ... back plate 14g ... hanging wall 14h ... front wall 14i ... process cartridge mounting part 14j ... end plate 14A ... cleaning chamber 14B ... waste toner accumulation chamber 15 ... photosensitive drum (Electrophotographic photosensitive drum) 15a
... Drum shaft 15b ... Cylinder 15c ... Center 16 ... Cleaning blade 16a ... Elastic blade
16b: support metal plate 17: charging means 17a: charging roller 17b: core shaft
17c compression coil spring 18 electrophotographic image forming apparatus main body 18a process cartridge mounting portion 19 feed blade 19a rotating shaft 19b flexible sheet 20 developing means 20Y yellow developing device 20YB
Coating blade 20YR Coating roller 20YS Developing roller 20YS-C Center 20M Magenta developing device 20MS Developing roller 20MS-C Center 20
C: cyan developing device 20CS: developing roller 20CS-
C: center 21: developing means 21B: black developing device 21BB: coating blade 21BS: developing roller 22: center shaft 22c: center 23: developing rotary 23a: center 23A: stays 23B, 23C: developing device support portion 23D: round hole 23
E: Slot 24: Squeeze sheet 25: Fixing unit 26: Fixing roller 27: Pressure roller 28: Heater 29: Heater 30: Scanner unit 31: Polygon mirror 32: Image forming lens 33: Reflection mirror 34: Discharge roller 35: Discharge Roller 36 ... Discharge roller 37 ... Discharge part 40 ... Roller abutting 41 ... Developing roller gear 42 ... Straight line 44A, 44B ... Swing center shaft 45 ... Drive gear 45c ... Center 46 ... Tangent line 47 ... Action line 54a, 54b ... Partition wall 54c ... Opening 54b1
... Arc-shaped part 57 ... Check valve 58 ... Check valve support 201 ... Drum drive shaft 202 ... Viscoelastic body 203 ... Mass body 204 ... Boss 205 ... Circle 300 ... Flange 302 ... Set screw

Claims (10)

[Claims] 1. An electrophotographic image forming apparatus capable of forming a multicolor image on a recording medium with a process cartridge detachably attached thereto, comprising: a process cartridge having an electrophotographic photosensitive drum and a cleaning unit; A developing device having a developer carrier for developing the latent image formed on the electrophotographic photosensitive drum by pressing using a toner, and an intermediate for multiply-transferring the toner image formed on the electrophotographic photosensitive drum A transfer body, and a swing center axis which is parallel to the longitudinal direction of the electrophotographic photosensitive drum and moves along an arc locus about a center of rotation, and the developer carrier swings around the swing center axis. Developing device moving means having an elastic member for supporting the developing device such that the developer carrying member can advance and retreat in a substantially radial direction with respect to the electrophotographic photosensitive drum; Mounting means for removably mounting a cartridge, wherein a mass body is mounted via a viscoelastic body inside the electrophotographic photosensitive drum or the intermediate transfer body. apparatus. 2. The electrophotographic photosensitive drum or the intermediate transfer member in the process cartridge includes a hollow cylindrical cylinder, a flange fixed to the cylinder, and a center axis fixed to the flange at the center of the cylinder. And
The electrophotographic image forming apparatus according to claim 1, wherein the viscoelastic body is mounted on a central axis. 3. The electrophotographic photosensitive drum or the intermediate transfer member in the process cartridge includes a hollow cylindrical cylinder, a flange fixed to the cylinder, and a center axis fixed to the flange at the center of the cylinder. The electrophotographic image forming apparatus according to claim 1, wherein the viscoelastic body is attached to a flange. 4. An electrophotographic photosensitive drum or an intermediate transfer body in the process cartridge has a hollow cylindrical cylinder and a flange fixed to the cylinder, and the viscoelastic body is attached to the cylinder. The electrophotographic image forming apparatus according to claim 1, wherein: 5. The apparatus according to claim 1, wherein the viscoelastic body and the mass body are provided symmetrically in the axial direction of the electrophotographic photosensitive drum or the intermediate transfer body. An electrophotographic image forming apparatus as described in the above. 6. The image forming apparatus according to claim 1, wherein the viscoelastic body and the mass body are provided at one intermediate position in the axial direction of the electrophotographic photosensitive drum or the intermediate transfer body.
An electrophotographic image forming apparatus according to any one of the preceding claims. 7. The viscoelastic body is made of nitrile rubber, Nosorex (inventor, please teach materials)
), A rubber material such as silicone rubber or malt plain, and the mass body is iron, stainless steel or brass.
7. The electrophotographic image forming apparatus according to claim 1. 8. A cylinder having a hollow cylindrical shape having a photosensitive layer on the outer periphery, a flange attached to both ends of the cylinder, a center shaft fixed to the center of the flange, and attached via a viscoelastic body in the cylinder. And a mass body. 9. A flange portion for connecting a hollow cylindrical cylinder portion having a dielectric material on its outer periphery to a center axis provided at the center of the cylinder portion, and a viscoelastic body is provided on the center axis or the center portion of the flange portion. And a mass attached via the intermediary transfer member. 10. A process cartridge detachable from a main body of an image forming apparatus for forming a multicolor image, comprising: an electrophotographic photosensitive drum; and cleaning for removing toner remaining after transfer to the electrophotographic photosensitive drum. Means, the electrophotographic photosensitive drum has a hollow cylindrical cylinder having a photosensitive layer on the outer periphery, a flange attached to both ends of the cylinder, a center axis fixed to the center of the flange, and a center axis. A mass body attached via a viscoelastic body.