JPH096086A - Color image forming device - Google Patents

Abstract

PURPOSE: To obtain a device in which developing units are arranged so as to exert balanced pressing force to a photoreceptor drum and a high quality image can be obtained by providing a transfer-material storage means and an intermediate transfer means below the photoreceptor drum, and also providing a particular number of the developing means so as to be horizontal to the photoreceptor drum and symmetrical with respect to one another, up and down and right and left, and so as to be pressed to the photoreceptor drum by means of pressing members. CONSTITUTION: Below the photoreceptor drum 10 are the paper feed cassette 15 storing the transfer materials P, and an intermediate transfer roller 41 abutting on the photoreceptor drum 10. The four developing units 13 are provided so as to be horizontal to the photoreceptor drum 10 and symmetrical with respect to one another, right and left and up and down, and so as to be pressed to the photoreceptor drum 10 by means of the pressing members. Color toner images formed on the periphery of the drum 10 are once transferred to the intermediate transfer roller 41. The toner images are retransferred in a transfer part by means of a transfer roller 45 to the transfer paper P fed by being sent out upward from the paper feed cassette 15 and by being synchronized with the toner image on the intermediate transfer roller 41 rotating counterclockwise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus for forming an image by arranging a charging means, an image exposing means and a developing means around an image forming body, and more particularly to a peripheral portion of the image forming body. The present invention relates to an electrophotographic image forming apparatus in which a plurality of charging units, an image exposing unit, and a developing unit are arranged to form a color image by superimposing toner images during one rotation of an image forming body.

[0002]

2. Description of the Related Art Conventionally, as one of methods for forming a multicolor image, a color image is formed by sequentially performing charging, image exposure and development for each color within one rotation of a photosensitive member which is an image forming member. There is known a color image forming apparatus for forming an image.

However, although the above-mentioned color image forming apparatus enables high-speed image formation as a method for forming a multicolored color image, a charging device, an image exposing means and a developing device are provided within one circumference of the photosensitive member. It is necessary to dispose a plurality of sets, and the image exposure optical system may be contaminated by toner leaking from the developing device in the vicinity, which may impair the image quality. To avoid this, it is necessary to increase the distance between the image exposing means and the developing device. Therefore, there is a contradiction that the diameter of the photoconductor is inevitably increased and the device is enlarged. For the purpose of avoiding this drawback, the substrate of the image forming body is formed of a transparent material, and a plurality of image exposing means are housed therein, and the image is exposed through the substrate to the photosensitive layer formed on the outer periphery thereof. An apparatus of the form is proposed, for example, by Japanese Patent Laid-Open No. 5-307307.

[0004]

However, although the color image forming apparatus according to the above-mentioned proposal accommodates a plurality of image exposing means in its inside to reduce the size, a plurality of charging devices, developing devices and transfer devices are provided outside. Since a large number of image forming process means such as a static eliminator and a cleaning device are arranged, it is difficult to downsize the device. Further, an image forming body is used in which the base of the photosensitive drum, which is the image forming body, is formed of a transparent material, and the photosensitive body layer is provided on the outer peripheral surface of the transparent base. Is arranged to press the image forming body, due to the imbalance of the pressing force of the blade of the developing device or the cleaning device, the image forming body is apt to be distorted, and the cylindrical image forming body is rotated during the driving of the image forming apparatus. On the other hand, the distance between the exposure optical system and the charging device may fluctuate,
However, there is a drawback in that stable rotation of the photosensitive drum cannot be obtained and a high quality image cannot be obtained. The inventors of the present application
Japanese Patent Application No. 6-3120 proposes to improve such a defect.
I went to No. 72. That is, as shown in the color image forming apparatus of the prior application of FIG. 6, four sets of developing devices 413 of yellow (Y), magenta (M), cyan (C) and black (K) are provided on the outer periphery of the photoconductor drum 410. It is arranged symmetrically to eliminate the imbalance of the pressing force of the developing device to the image forming body and to stabilize the rotation of the photosensitive drum.
5, it is necessary to arrange the sheet feeding portion reaching the transfer device 414a through the timing roller 416, the transfer device 414a, the static eliminator 414b, the conveyor belt 414e, and the like in proximity to the photoconductor drum 410. The arrangement of the Y and K developing units arranged below 410 is limited, and it cannot be said to be sufficient as a solution to the above-mentioned drawbacks. Further, there is a drawback that it is difficult to feed, convey, and eject the transfer material due to the restriction of the transfer area.

As a result of solving and improving this point, the present invention provides
A plurality of developing units arranged outside the image forming body are arranged in a well-balanced manner with respect to the pressing force applied to the image forming body, and a cylindrical image forming body that rotates while the color image forming apparatus is driven, a developing unit and an exposure unit. The objective is to provide a color image forming apparatus that can obtain high-quality images without fluctuations in the gap between the optical system and the charging device, and to easily feed, convey, and eject jams of transfer materials. The present invention is intended to provide a color image forming apparatus.

[0006]

The above object is to provide a cylindrical image forming body for forming a latent image, a charging means and a developing means on the outer periphery of the image forming body, and an image exposing means on the inner periphery of the image forming means. A combination of the charging means, the image forming body is charged by the charging means, the image forming body is exposed by the image exposing means, and a toner image is formed on the image forming body by development by the developing means. In a color image forming apparatus that forms an image by superimposing the toner images on the image forming body by repeating the above, the transfer material storing means for storing the transfer material below the image forming body and the image forming body And an intermediate transfer unit that comes into contact with the image forming unit. The four developing units are arranged horizontally by a pressing member with respect to the image forming unit and press the image forming unit vertically and horizontally symmetrically. Set up The toner image formed on the image forming body by the developing means is once transferred to the intermediate transfer means, and then the toner image is transferred onto the transfer material fed from the transfer material accommodating means. This is achieved by a color image forming apparatus characterized by more retransfer.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming process and each mechanism of an embodiment of a color image forming apparatus constituting the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention, FIG. 2 is a main part diagram of FIG. 1 showing a preferred arrangement of developing devices, and FIG. 2 is a cross-sectional view taken along line AOA of FIG.
FIG. 3 is a diagram showing a drive gear of a photosensitive drum.

The color image forming apparatus of this embodiment uses a photoconductor drum in which the base of the photoconductor drum, which is an image forming body, is formed of a transparent material, and a photoconductor layer is provided on the outer peripheral surface of the transparent base. An image exposure unit is arranged inside the photosensitive drum, and an image forming process unit such as a charger, a developing unit, an intermediate transfer roller, and a cleaning unit is arranged outside the photosensitive drum.

The photosensitive drum 10, which is an image forming body, is provided with, for example, a cylindrical base body formed of a transparent member such as optical glass or a transparent acrylic resin inside, and a transparent conductive layer, a- A photosensitive layer such as a Si layer or an organic photosensitive layer (OPC) is formed on a drum, and is driven and rotated clockwise in a grounded state.

In this embodiment, in the photoconductor layer of the photoconductor drum, which is the image formation point of the exposure beam for image exposure, an appropriate contrast is obtained with respect to the light attenuation characteristics (photocarrier generation) of the photoconductor layer. It suffices that the exposure light amount has a wavelength that can be applied. Therefore, the light transmittance of the transparent substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic that some light is absorbed when the exposure beam is transmitted. As the material of the light-transmitting substrate, acrylic, fluorine, polyester, polycarbonate, polyethylene terephthalate, which is used for soda glass, Pyrex glass, borosilicate glass and general optical members,
Various translucent resins such as can be used. In addition, as a transparent conductive layer, indium tin oxide (IT
O), tin oxide, lead oxide, indium oxide, copper iodide,
A light-transmissive metal thin film made of Au, Ag, Ni, Al, or the like is used. As a film forming method, a vacuum deposition method, an active reaction deposition method, various sputtering methods, various CVD methods,
A dip coating method, a spray coating method, or the like is used. Also,
As the photoconductor layer, amorphous silicon (a-S
i) An alloy photosensitive layer, an amorphous selenium alloy photosensitive layer, or various organic photosensitive layers (OPC) can be used.

The scorotron charger 11, which is a charging means, is used in the image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and the above-described organic photosensitive member of the photosensitive drum 10 is used. The body layer is charged by a control grid held at a predetermined potential and a corona discharge by a discharge wire to give a uniform potential to the photoconductor drum 10.

An exposure optical system 12 which is an image exposure means for each color.
Is a linear FL (phosphor emission), EL (electroluminescence), PL (plasma discharge), LE in which light emitting elements arranged in the axial direction of the photoconductor drum 10 are arranged in an array.
D (light emitting diode), linear LISA (photomagnetic effect optical shutter array) in which elements having an optical shutter function are arranged, PLZT (transmissive piezoelectric element shutter array), L
An exposure element such as a CS (liquid crystal shutter) and a SELFOC lens as a unity-magnification imaging element are configured as a unit, and are attached to a support member 20 provided inside the photoconductor drum 10 and separately provided. The image signals of the respective colors read by the image reading device are sequentially taken out from the memory and input as electric signals to the exposure optical system 12 for the respective colors. The emission wavelength of the light emitting device used in this example is in the range of 600 to 900 nm.

Development which is a developing means for each color using a non-contact developing method in which one-component or two-component developers of yellow (Y), magenta (M), cyan (C) and black (K) are contained respectively. Each of the containers 13 is a photosensitive drum 10.
The developing sleeve 131 rotates in the same direction with a predetermined gap from the peripheral surface of the developing sleeve 131.

The developing device 13 for each color described above applies an electrostatic latent image on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure optical system 12 by applying a developing bias voltage. Reverse development in a non-contact state.

The original image is temporarily read as an image signal for each color of Y, M, C and K from an image read by an image pickup device or an image edited by a computer in an image reading apparatus separate from this apparatus. Stored and stored in memory.

When the image recording is started, the photoconductor drive motor is rotated to rotate the photoconductor drum 10 clockwise.
At the same time, application of electric potential to the photoconductor drum 10 is started by the charging action of the Y scorotron charger 11.

After a potential is applied to the photoconductor drum 10, the exposure by the electric signal corresponding to the first color signal, that is, the Y image signal is started in the Y exposure optical system 12, and the rotation of the drum causes the exposure. An electrostatic latent image corresponding to the Y image of the original image is formed on the photosensitive layer on the surface.

The latent image is reversal-developed by the Y developing device 13 with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is given a potential on the yellow (Y) toner image by the charging action of the magenta (M) scorotron charger 11, and M
Exposure of the second optical signal of the exposure optical system 12, that is, the electric signal corresponding to the M image signal,
The magenta (M) toner image is sequentially superimposed on the yellow (Y) toner image by the non-contact reversal development by No. 3.

By the same process, the cyan (C) scorotron charger 11, the exposure optical system 12 of C and the developing device 13 of C further cause a cyan (C) toner image corresponding to the third color signal to become black. The (K) scorotron charger 11, the exposure optical system 12, and the developing device 13 sequentially form a black (K) toner image corresponding to the fourth color signal in a superimposed manner, and within one rotation of the photoconductor drum 10. A color toner image is formed on the peripheral surface.

These Y, M, C and K exposure optical systems 12
The exposure of the organic photosensitive layer of the photoconductor drum 10 is performed through the transparent substrate described above from the inside of the drum.
Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the same exposure as the image corresponding to the first color signal is performed. It is possible to form an electrostatic latent image. In order to stabilize the temperature inside the photosensitive drum 10 and prevent the temperature from rising due to the heat generated by the exposure optical system 12, a material having good thermal conductivity is used for the supporting member 20, a heater is used for low temperature, and a high temperature is used for high temperature. Can be suppressed to the extent that there is no problem by taking measures such as radiating heat to the outside through a heat pipe.

In addition, the replenishment developer for each color is supplied to the replenishment tank 21.
Further, the toner is supplied to the developing device 13 of a corresponding color and agitated by the two agitating rollers 136 and 137.
Is supplied to. Abutting rollers 138a and 138b are provided at both ends outside the image area of the developing sleeve 131.

The developing sleeve 131 is kept in non-contact with the photoconductor drum 10 by abutting rollers 138a and 138b which are brought into contact with the photoconductor drum 10, and are fixed inside when developing by the developing device 13 for each color. Magnet 13
A developing bias applied with a direct current or an alternating current is applied to the developing sleeve 131 in which 2 is arranged, jumping development is performed by a one-component or two-component developer accommodated in the developing device, and the transparent conductive layer is grounded. A DC bias having the same polarity as the toner is applied to the drum 10 to perform non-contact reversal development in which the toner is attached to the exposed portion. The developer on the developing sleeve 131 after development is scraped off by a scraping plate 134.

Subsequently, the color toner image formed on the peripheral surface of the photosensitive drum 10 is temporarily transferred onto the intermediate transfer roller 41 by the action of the intermediate transfer roller 41. The color toner image formed on the peripheral surface of the intermediate transfer roller 41 is sent upward from the paper feeding cassette 15 which is a transfer material storing means provided below the photoconductor drum 10 at the transfer portion, and is horizontally leveled. The upper and lower guide plates 1 of the arranged paper feed section
A transfer material, which is a transfer material, which is fed horizontally to the timing roller 16 via 5a and 15b and is fed in synchronization with the toner image on the intermediate transfer roller 41 rotating counterclockwise by the drive of the timing roller 16. It is retransferred onto the paper P by the transfer roller 45 as a transfer device.

The transfer roller 45 is synchronized with the transfer paper P fed to the transfer portion by the timing roller 16, and the transfer of the length of the transfer paper P is performed in the circumferential direction of the intermediate transfer roller 41. A controller provided in an image forming apparatus (not shown) and a transfer roller so that the intermediate transfer roller 41 is pressed against the intermediate transfer roller 41 only during a period of time and is separated from the intermediate transfer roller 41 when the transfer process is not performed. It is operated by the pressure contact release mechanism.

After the transfer of the toner image, the transfer paper P is separated from the peripheral surface of the intermediate transfer roller by the curvature of the intermediate transfer roller 41, and then horizontally transferred to the fixing device 17 via the transfer belt 14e which is a transfer means. After the toner is fused and fixed on the transfer paper P by being heated and pressed by the heating roller 17a and the pressure-bonding roller 17b in the fixing device 17, the toner is fused and fixed on the transfer paper P, and then on the tray on the side of the color image forming apparatus 100 via the paper discharge roller 18. The toner image surface is discharged downward.

Paper feed to the registration roller 16, the intermediate transfer roller 41, the transfer roller 45, the conveyor belt 14e, the fixing device 17, and the paper ejection roller 18 from the upper and lower guide plates 15a and 15b forming a horizontal paper feed conveyance paper ejection path. Since the conveying and discharging path is formed horizontally, the toner image is satisfactorily transferred onto the transfer sheet P, and the transfer sheet P is less likely to jam.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
In the cleaning device 19, the surface of the photoconductor drum 10 is rubbed by the cleaning blade 19a in the cleaning device 19 to remove the residual toner, and the toner image of the original image is continuously cleaned or temporarily stopped, or the toner image of the new original image is temporarily stopped. Take formation. The waste toner scraped off by the cleaning blade 19a and the cleaning roller 19b is discharged to the waste toner container 22 through the toner transport screw 19c and the toner transport pipe 19d. After the cleaning is completed, the cleaning blade 19a and the cleaning roller 19b are kept apart from the photoconductor drum 10 in order to prevent damage to the photoconductor drum 10.

The photosensitive drum 10 is the exposure optical system 1
As a result of accommodating 2 inside thereof and improving the transfer area, even if the diameter of the drum is relatively small, the plurality of scorotron chargers 11, the developing device 13, the cleaning device 19, and the intermediate transfer roller 41 described above are provided on the outer peripheral surface thereof. It is possible to use a small diameter drum having an outer diameter of 60 mm to 200 mm, and it is possible to make the volume of the apparatus compact.

As described above, by providing the intermediate transfer roller 41 under the photosensitive drum 10, the lower space including the transfer area of the photosensitive drum can be used and is arranged on the outer peripheral surface of the photosensitive drum 10. Of the set of developing devices 13, the arrangement area of the Y and K developing devices arranged on the lower side becomes wider,
It is possible to dispose the Y and K developing devices below the horizontal line passing through the center of the photoconductor drum than that proposed in Japanese Patent Application No. 6-312072, which is a prior application. However, the angle α described later can be increased.

A horizontal line Q is passed through the center of the photosensitive drum 10.
The developing sleeves 13 for Y, M, C and K are bisected by 1-O-Q2 and are provided on the diagonal line formed at an angle α.
The center of 1 is arranged and the abutting roller 1 provided in each developing device 1
38a and 138b are vertically symmetrical with respect to the center of the photoconductor drum 10 and symmetrically with respect to the center of the photoconductor drum 10 so that they are pressed against the photoconductor drum 10 with a uniform pressing force.
Four developing devices 13 of C and K are arranged. Developing device 13
Is pressed by a pressing spring (not shown), for example, a pressing spring, and the abutting rollers 138a and 138b press-contact the photosensitive drum 10. Developing device 1 above and below Y, M and C, K
The angle α formed by the center of the photosensitive drum 10 of 3 is preferably 60 ° or more and 90 ° or less, and when it is less than 60 °, the rotation of the image forming body tends to be unstable, and when it is greater than 90 °, the developing device is The pressure of is not stable.

As described above, due to the restriction of the transfer area of the color image forming apparatus and the improvement of the feeding, feeding and discharging system of the transfer material, the cylindrical image forming body which rotates during the driving of the image forming apparatus is used. A cylindrical image forming body which is rotated during driving of the image forming apparatus, by which a stable rotation of the photosensitive drum can be obtained by a balanced pressing force of a plurality of developing units arranged outside the image forming body. , It is possible to provide an image forming apparatus in which a good image is maintained without causing a change in a gap between a developing device, an exposure optical system, and a charging device, and particularly, a superposed toner requiring uniform exposure for each color. It became possible to form a color image having a good image.

Further, a line O-Q perpendicular to the horizontal line is provided so that the force balance with respect to the photosensitive drum 10 is maintained.
3, the angles β and γ are formed on the right and left sides of the photosensitive drum 1.
A cleaning device 19 provided with a cleaning blade 19a is disposed in contact with the intermediate transfer roller 40 and the photoconductor drum 10 in contact with 0. Β is preferably 5 ° or more and 45 ° or less and the contact position γ of the cleaning blade 19 is also preferably 5 ° or more and 45 ° or less so that the transfer area of the intermediate transfer roller becomes appropriate. Stabilization of the photoconductor drum by the balanced pressing force of the cleaning device blade and the intermediate transfer roller in addition to the balanced pressing force of the plurality of developing devices arranged outside the image forming body. The obtained rotation is obtained.

Further, as a condition that the relationship of the magnetic pole angle with respect to the image forming body is the same between the developing sleeves so that the upper and lower developing devices can be commonly used, α = 60 ° is set between the magnetic poles of N and S near the developing area. Angle δ is 60 °, 30 °, α = 90
And the angle δ between the magnetic poles of N and S near the developing area is 90.
It is preferable that the fixed magnetic poles are arranged at an angle of 45 °, 22.5 °, or the like.

The photosensitive drum 10 has front and rear flanges 111,
Bearing 14 which is a bearing member attached to the rear plate 103 of the process unit 110.
1 and the front flange 111 can be fitted into the process unit 1
10 is supported by the bearing 143 which is a bearing member attached to the front side plate 102 of the process unit 1.
10 is rotatably mounted. A bearing 14 provided on the rear side plate 103 in a state where the support member 20 to which the exposure optical system 12 is attached is included in the photosensitive drum 10.
2 and a bearing 143 provided on the front side plate 102, and fixed to the front side plate 102 with screws. A cleaning device 19, a scorotron charger 11 of each color, a developing device 13 of each color, and a replenishment tank 21 of a developer of each color are attached to the outer periphery of the photoconductor drum 10, and the process unit 11
0 is configured.

The process unit 110 is taken out above the color image forming apparatus 100 by opening an opening / closing lid (not shown) provided on the upper part of the color image forming apparatus 100, and the photoconductor drum 10 provided in the process unit 110.
Process members such as the exposure optical system 12, the cleaning device 19, the scorotron charger 11, the developing device 13, and the replenishing tank 21 are maintained and replaced.

The developing device 13 and the replenishing tank 21 corresponding to each color of Y, M, C and K are formed as an integral developing device unit 130 as shown by the dotted line in FIG. Opening and closing doors (not shown) provided on both sides of 110 open the developing device unit 130 to the left and right to replace the replenishing tank 21.

When the process unit 110 is mounted on the color image forming apparatus 100, the gear 10g provided on the rear flange 112 of the photoconductor drum and the gear connected to the drive motor of the photoconductor drum provided on the apparatus main body (not shown). The photoconductor drum 10 can be rotated by coupling with G1.

To ensure the registration of the superimposed toner image, the number of teeth Z2 of the gear 10g around the photosensitive drum 10 corresponding to the angle α formed by the Y, M, C, and K developing devices 13 described above.
And the number of teeth Z1 of the gear G1 is preferably Z2 = nZ1 (n is a positive integer).

In the above embodiment, the process unit 11
When 0 is attached to or detached from the color image forming apparatus 100, the unillustrated joining portion between the toner transport pipe 19d and the waste toner container 22 is released and joined.

FIG. 5 is a diagram showing a jam process, and at the time of jam, the paper feed cassette 15 and the upper and lower guide plates 15a and 15b, the registration rollers 16 and the intermediate transfer which constitute a horizontal paper feed transport paper discharge path. Roller 41, transfer roller 4
5, transport belt 14e, fixing device 17, paper discharge roller 18
Then, the paper feeding / conveying unit 150 including the waste toner container 22 provided between the paper feeding / conveying and discharging path and the paper feeding cassette 15 is pulled out from the color image forming apparatus 100, and the transfer paper in the jam state is removed. .

Further, the upper guide plate 15a and the intermediate transfer roller 41 are opened around the support shaft 15c to facilitate the jam processing. Further, the lower guide plate 1 is centered around the support shaft 15d.
5b is opened at the upper part, and the waste toner container 22 is replaced. The sheet feeding / conveying unit 150 is the color image forming apparatus 10.
When the toner transport pipe 19d and the waste toner container 22 are detached from each other, the joint portion (not shown) is released and joined.

[0043]

According to the first or second aspect of the present invention, the transfer area of the color image forming apparatus is restricted, and the transfer material is fed and conveyed.
As a result of the improvement of the paper discharge system, the photosensitive drum is rotated by a balanced pressing force of a plurality of developing devices arranged outside the image forming body with respect to the cylindrical image forming body rotating while the image forming apparatus is driven. A stable rotation of the body drum can be obtained, and a good image can be obtained without changing the gap between the cylindrical image forming body that rotates during the driving of the image forming apparatus and the developing device, the exposure optical system, or the charging device. It is possible to provide an image forming apparatus that is maintained,
In particular, it has become possible to form a good color image of a superimposed toner image that requires uniform exposure for each color.

According to the third aspect, in addition to the well-balanced pressing force of the plurality of developing devices arranged outside the image forming body, the balance including the blade of the cleaning device and the intermediate transfer roller is well balanced. Stable rotation of the photosensitive drum due to the pressing force is obtained, and there is no fluctuation in the gap between the cylindrical image forming body that rotates during the driving of the image forming apparatus, the developing device, the exposure optical system, and the charging device. It is possible to provide an image forming apparatus capable of maintaining a good image, and in particular, it is possible to form a good color image of a superimposed toner image which requires uniform exposure for each color.

According to the fourth aspect, as a result of improving the restriction of the transfer area and the feeding, conveying and discharging system of the transfer material, the intermediate transfer means, the paper feeding means and the fixing device can be integrally withdrawn, and the transfer material It has become possible to provide a color image forming apparatus that can easily perform a paper feed and paper discharge system jam process.

According to the fifth aspect, as a result of improving the transfer area of the color image forming apparatus, the photosensitive drum can be downsized, and in particular, the color image forming apparatus can be downsized.

[Brief description of drawings]

FIG. 1 is a sectional configuration view of a color image forming apparatus showing one embodiment of the present invention.

FIG. 2 is a diagram showing a preferred arrangement of a developing device in the principal part view of FIG.

3 is a cross-sectional view taken along the line AOA in FIG.

FIG. 4 is a diagram showing a drive gear of a photosensitive drum.

FIG. 5 is a diagram illustrating a jam process.

FIG. 6 is a diagram showing a color image forming apparatus of a prior application.

[Explanation of symbols]

 10 Photoconductor Drum 11 Scorotron Charger 12 Exposure Optical System 13 Developer 15 Paper Feed Cassette 20 Supporting Member 41 Intermediate Transfer Roller 45 Transfer Roller 100 Color Image Forming Device 110 Process Unit 130 Developer Unit 131 Development Sleeve 138a, 138b Abutting Roller 150 Paper feed transport unit P Transfer paper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Hama ▼ Tauta Takata 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Stock Company

Claims (5)

[Claims] 1. A cylindrical image forming body for forming a latent image, a charging means and a developing means on the outer periphery of the image forming body, and four sets of image exposing means on the inner periphery of the image forming body. The image forming is repeated by charging the image forming body by the image forming means, exposing the image forming body by the image exposing means, and forming a toner image on the image forming body by developing by the developing means. In a color image forming apparatus for forming an image by superimposing the toner image on the body,
A transfer material accommodating means for accommodating a transfer material and an intermediate transfer means contacting the image forming body are provided below the image forming body, and the four sets of developing means are respectively pressed against the image forming body by pressing members. The toner image formed on the image forming body by the developing means is once transferred to the intermediate transfer means by being arranged horizontally and provided to press the image forming body at vertically symmetrical and horizontally symmetrical positions. After that, the color image forming apparatus is characterized in that the toner image is retransferred to the transfer material fed from the transfer material storage means by the intermediate transfer means. 2. The angle formed between the center of the developing sleeve of the developing means and the center of the image forming body which are symmetrically arranged in the vertical direction is 60 ° or more and 90 ° or less. The image forming apparatus according to item 1. 3. An angle formed by a vertical line passing through the center of the image forming body and a contact position between the intermediate transfer unit and the image forming body is 5 ° or more and 45 ° or less. Item 1
Alternatively, the color image forming apparatus described in 2. 4. The intermediate transfer means, the transfer material accommodating means, and a fixing device for fixing the toner image are integrated into a unit, and the unit is provided so as to be pulled out to the color image forming apparatus. The color image forming apparatus according to any one of claims 1 to 3. 5. The diameter of the image forming body is 60 mm or more, 2
The color image forming apparatus according to claim 1, wherein the color image forming apparatus has a length of 00 mm or less.