JPH09325561A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a device capable of keeping the strength of a device base plate and reducing the occurrence of each other's positional deviations in rays of image exposure light from plural image exposure means caused by drive unevenness at the time of driving an image carrier by forming an opening hole for pulling out a photoreceptor drum and opening holes for developing units, in a state where the opening holes are separated. SOLUTION: The opening hole 70A for pulling out the photoreceptor drum and the respective opening holes 70B (C, K, M and Y) of the developing units 13 (C, K, M and Y) are formed in the separated state. An image forming unit in which the photoreceptor drum 10 and respective exposure optical systems are integrated is horizontally moved so that the image forming unit can be taken out of a device main body through the opening hole 70A as an image forming body opening part of a front plate as the device base plate. Further, the respective developing units 13 arranged around the photoreceptor drum are made retreated states up to fixed positions, in nearly horizontal directions orthogonally crossing a direction where the photoreceptor drum is pulled out, so that the respective developing units 13 can be nearly horizontally pulled out of the retreated positions through the respective opening holes 70B, in the same direction as the pulling out direction of the photoreceptor drum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, and a FAX, in which a plurality of charging means, image exposing means and developing means are arranged around the image forming body. The present invention relates to an electrophotographic color image forming apparatus that forms a color image by superimposing toner images while rotating.

[0002]

2. Description of the Related Art Conventionally, as one method of forming a multi-color image, image formation of an image corresponding to each color is sequentially repeated during one rotation of an image forming body to form a toner image of each color. 2. Description of the Related Art A color image forming apparatus that forms a color image by superimposing on a body is known.

However, in such an apparatus, a plurality of charging means, image exposing means, and developing means are arranged on the peripheral surface of the image forming body, and furthermore, a space is also required in a transfer material conveying area and a cleaning means. Insufficient peripheral space,
Therefore, there are drawbacks that layout is difficult, a large-sized image forming body having a long peripheral surface is required, and the balance is poor.

[0004] As one method of solving this shortage of space, the present invention has made the substrate of the image forming body transparent,
A device in which each image exposing means is housed inside the image forming body, and the image is exposed from the inside of the image forming body, and the transfer transferred from the tangential direction to the transfer area by using the intermediate transfer body. Japanese Patent Application No. 8-76560 proposes an apparatus in which the conveying surface of the material is set at a position away from the peripheral surface of the image forming body.

[0005]

However, in such an apparatus, the image exposure means is generally in the state of a unit integrated with the image forming body for the purpose of maintaining the exposure accuracy on the photosensitive surface and simplifying the handling. In many cases, it is incorporated into the apparatus. Therefore, when attaching or detaching the image forming body, an opening hole which is an opening of the image forming body is provided in the device substrate of the apparatus main body, and a plurality of sets of image exposing means and image forming means are formed through the opening hole. The unit integrated with the body is drawn out. However, if an attempt is made to further provide a developing means opening portion, which is an opening hole of the developing means arranged around the image forming body, on the apparatus substrate, the strength of the apparatus substrate is reduced. When the image forming body is driven, it becomes weak, and the positional deviation of the image exposure light from the plurality of image exposing means occurs due to uneven driving, which causes a problem of image blurring.

According to the present invention, the above problems are improved, the strength of the apparatus substrate is maintained, and the positional deviation of the image exposure light from the plurality of image exposure means due to uneven driving during driving of the image forming body occurs. It is an object of the present invention to provide a color image forming apparatus with less charge.

[0007]

The above-mentioned object is to arrange a plurality of sets of charging means, image exposing means and developing means around a rotating image forming body so that during one rotation of the image forming body, A plurality of toner images are superposed on the image forming body by sequentially repeating the formation of the toner image by the charging by the charging means, the image exposure by the image exposing means and the development by the developing means on the image forming body. Then, in a color image forming apparatus for collectively transferring the superposed toner images onto a transfer material, the plurality of sets of image exposing means and the image forming body are integrated into one unit, and the unit is the color image forming apparatus. Through the opening of the image forming body of the apparatus substrate provided in the image forming body, the color image forming apparatus can be drawn out in a direction substantially horizontal to the center of the image forming body, and the plurality of developing units can be connected to the image forming body. Is accomplished by issuing a color image forming apparatus is characterized in that a retractable to a position spaced from said imaging member in a direction perpendicular to the direction.

[0008]

Embodiments of the present invention will be described below. The description of the present application does not limit the technical scope of the claims or the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.

An image forming process and configuration of an embodiment of a color image forming apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus,
FIG. 2 is a front view showing a support structure of the image forming body, and FIG.
FIG. 4 is a cross-sectional view showing a support structure of the image forming body.
5 is an external view of the image forming unit, FIG. 5 is a front view showing a supporting structure of the intermediate transfer belt, and FIG. 6 is a sectional view showing the supporting structure of the intermediate transfer belt.

According to FIG. 1, a photosensitive drum 10, which is a drum-shaped image forming body, is provided with a cylindrical transparent resin substrate formed of a transparent member of transparent acrylic resin inside, and a transparent conductive layer. And an organic photoconductor layer (OPC) formed on the outer circumference of the substrate, and in a state of being grounded.
It is rotated counterclockwise as indicated by the arrow.

In the present embodiment, it is sufficient that the photoconductive layer of the photosensitive drum has an exposure light amount that can provide an appropriate contrast. Therefore, the light transmittance of the transparent resin substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic such that a certain amount of light is absorbed when the exposure beam is transmitted. As a material of the light-transmitting substrate, an acrylic resin, particularly one polymerized using a methyl methacrylate monomer, is preferably used because it is excellent in transparency, strength, precision, surface properties, and the like, but is used for other general optical members and the like. Various translucent resins such as fluorine, polyester, polycarbonate, polyethylene terephthalate, and the like can be used.

Further, it may be colored as long as it has a property of transmitting exposure light. The refractive index of these resins is approximately 1.5. Examples of the method for forming the light-transmitting conductive layer include a vacuum deposition method, an active reaction deposition method, various sputtering methods, and various C methods.
Using the VD method, indium tin oxide (IT
O), alumina, tin oxide, lead oxide, indium oxide, copper iodide, or a thin film of light transmissivity such as Au, Ag, Ni, Al or the like is used, or a dip coating method, a spray coating method, or the like is used. A conductive resin composed of the above-mentioned metal fine particles and a binder resin is used. Further, various organic photoconductor layers (OPC) can be used as the photoconductor layer.

Further, after adding a catalyst for synthesizing and polymerizing the plastic material monomer, it is poured into a cylindrical mold, hermetically sealed and fixed by a side plate, and this is rotated at a high speed and appropriately heated. This promotes uniform polymerization. After completion of the polymerization, the mixture is cooled, the obtained transparent resin substrate is taken out of the mold, cut and, if necessary, subjected to a finishing step to produce a transparent resin substrate for a photosensitive drum of an image forming apparatus (centrifugal polymerization method). .

As a material for a transparent resin substrate of a transparent plastic molded by centrifugal polymerization, a polymer obtained by using a methyl methacrylate monomer as described above is the best in terms of transparency, strength, precision and surface property. In addition, polyethyl methacrylate, polybutyl methacrylate, polyethyl acrylate, polybutyl acrylate, polystyrene, polyimide, polyester, polyvinyl chloride, or the like, or a copolymer thereof or the like can be used. In the centrifugal polymerization method, since the roundness is determined by the mold used for molding, a highly accurate substrate can be obtained. Also,
The uneven thickness varies depending on the rotation unevenness and viscosity during polymerization and the heating conditions during polymerization.

By using the plastic cylindrical transparent resin substrate manufactured by the above manufacturing method, a photosensitive drum having a uniform wall thickness and excellent cylindricalness and roundness of the cylindrical substrate is provided. It

Reference numeral 11 denotes a scorotron charger (hereinafter simply referred to as a charger), which performs a charging operation on the above-described organic photosensitive layer of the photosensitive drum 10 by a grid held at a predetermined potential and corona discharge by a discharge wire. A uniform potential is applied to the photoconductor drum 10.

Reference numeral 12 is an image exposing means, that is, the photosensitive drum 1.
An exposure optical system composed of LEDs arranged in the axial direction of 0 and a SELFOC lens which is an equal-magnification imaging system, in which image signals of respective colors read by a separate image reading device are sequentially taken out from a memory. An electric signal is input to each of the exposure optical systems 12 described above.

Each of the exposure optical systems 12 is mounted on a supporting member 20 provided as an optical system supporting means, and is housed inside the base of the photosensitive drum 10.

Reference numerals 13Y to 13K denote developing units containing yellow (Y), magenta (M), cyan (C), and black (K) developers, respectively, and each has a predetermined gap with respect to the peripheral surface of the photosensitive drum 10. And a developing sleeve 130 that rotates in the same direction as the photosensitive drum 10 in the developing region while maintaining the above.

Each of the developing devices is in a non-contact state by applying a developing bias voltage to the electrostatic latent image on the photosensitive drum 10 formed by the charging by the charging device 11 and the image exposure by the exposure optical system 12 described above. Reverse development with.

The original image is temporarily stored in an image reading apparatus separate from the present apparatus, as an image read by an image sensor or an image edited by a computer as image signals for each of Y, M, C and K colors. And stored.

At the start of image recording, the photosensitive drum driving motor starts to rotate the photosensitive drum 10 in a counterclockwise direction, and at the same time, application of a potential to the photosensitive drum 10 is started by the charging action of the charger 11 (Y). You.

After a potential is applied to the photosensitive drum 10, exposure by an electric signal corresponding to a first color signal, that is, an image signal of yellow (Y) is started in the exposure optical system 12 (Y), and the drum is exposed. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface by rotational scanning.

The latent image is reversal-developed by the developing device 13 (Y) 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 photoconductor drum 10 is given a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second color signal of the exposure optical system 12 (M), that is, Exposure is performed by an electric signal corresponding to the magenta (M) image signal, and non-contact reversal development by the developing device 13 (M) causes a magenta (M) toner image on the yellow (Y) toner image. Will be sequentially stacked.

By the same process, the charger 11 (C),
The exposure optical system 12 (C) and the developing unit 13 (C) further form a cyan (C) toner image corresponding to the third color signal, and the charging unit 11 (K), the exposure optical system 12 (K) and the developing unit 13 (C). A black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the unit 13 (K), and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10. You.

Photosensitive drum 1 using each of these exposure optical systems
The exposure of the organic photosensitive layer of No. 0 is performed from the inside of the drum through a substrate transparent to the above-mentioned exposure wavelength. 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. Each exposure optical system 1
In order to stabilize the temperature in the photosensitive drum 10 and prevent the temperature from rising due to the heat generated by 2, heat is used for the supporting member 20, a heater is used for low temperature, and a heat pipe is used for high temperature. By taking measures such as radiating heat to the outside via the, it can be suppressed to the extent that there is no problem.
Further, at the time of the developing action by each developing device, a developing bias to which a direct current or a further alternating current is applied is applied to the developing sleeve 130, and a jumping development is performed by a one-component or two-component developer contained in the developing device, so that the developing sleeve 130 is transparent. Non-contact reversal development is performed on the photosensitive drum 10 that grounds the conductive layer.

Thus, the color toner image formed on the peripheral surface of the photosensitive drum 10 is temporarily transferred to the peripheral surface of the intermediate transfer belt 14 provided as intermediate transfer means.

The intermediate transfer belt 14 has a thickness of 0.5 mm.
A 2.0 mm endless rubber belt, a semiconductive substrate of silicon rubber or urethane rubber having a resistance of 10 ⁸ Ω · cm to 10 ¹² Ω · cm, and a toner filming prevention layer outside the rubber substrate. It has a two-layer structure in which a fluorine coating having a thickness of 5 μm to 50 μm is performed. This layer also preferably has a similar semiconductivity. Instead of the rubber belt substrate, semiconductive polyester, polystyrene, polyethylene, polyethylene terephthalate, or the like having a thickness of 0.1 mm to 0.5 mm can also be used. The intermediate transfer belt 14 is stretched between the rollers 14A, 14B, 14C, and 14D, and is circulated and conveyed in a clockwise direction in synchronization with the peripheral speed of the photosensitive drum 10 by the power transmitted to the roller 14D.

The intermediate transfer belt 14 has a roller 14A.
The belt surface between the roller 14B and the roller 14B is in contact with the peripheral surface of the photosensitive drum 10, while the belt surface on the outer periphery of the roller 14C is in contact with the transfer roller 15, which is a transfer member. Has formed.

The color toner image adhered to the peripheral surface of the photoreceptor drum 10 is sequentially intermediate-transferred by applying a bias voltage having a polarity opposite to that of the toner to the roller 14B at a contact point with the intermediate transfer belt 14. The image is transferred to the peripheral surface of the belt 14. That is, the color toner image on the drum is conveyed to the transfer area without scattering the toner by the guide of the roller 14A which is grounded, and is transferred to the roller 14B by 1
By applying a bias voltage of kV to 2 kV, the image is efficiently transferred to the intermediate transfer belt 14 side.

On the other hand, the transfer paper P is carried out by the operation of the paper feed roller 17 of the paper feed cassette (not shown) and fed to the timing roller 18, and is synchronized with the transfer of the color toner image on the intermediate transfer belt 14. The paper is fed to the transfer area of the transfer roller 15.

The transfer roller 15 is connected to the intermediate transfer belt 14.
The transfer paper P fed in the counterclockwise direction is synchronized with the peripheral speed of the intermediate transfer in the transfer area formed by the nip portion between the transfer roller 15 and the roller 14C in the ground state. The color toner images are successively transferred onto the transfer paper P by applying a bias voltage having a polarity opposite to that of the toner of 1 kV to 2 kV to the transfer roller 15 in close contact with the color toner image on the belt 14.

The transfer paper P to which the color toner image has been transferred is neutralized, conveyed to the fixing device 91 via the conveyance plate 19, sandwiched and conveyed between the heat roller 91A and the pressure roller 91B, and heated. After the toner is fused and fixed, the toner is discharged to the outside of the apparatus via a discharge roller 92.

Cleaning devices 100 and 140 are installed on the photoconductor drum 10 and the intermediate transfer belt 14, respectively, and the blades of the cleaning devices 100 and 140 are constantly in pressure contact with each other to remove the remaining adhered toner and to keep the peripheral surfaces always. It is kept clean.

According to FIGS. 2 to 4, the support member 20 described above is used.
Is constituted by a pair of front and rear members fixed to the rotation support shaft 30 of the photosensitive drum 10, and each of the exposure optical systems 12
Both ends are adjusted so that the distance to the photosensitive surface is in a predetermined positional relationship via a wedge-shaped sticking member 21, and is fixed to the adjustment position by bonding.

On the other hand, in the photosensitive drum 10, flange members 10A and 10B provided at both ends are rotatably supported by the support member 20 via bearings B, respectively, and driven by a gear 10G provided in the flange member 10B. The rotation support shaft 30 in the fixed state is rotated about the rotation center.

The photosensitive drum 10 and the exposure optical systems 12 are coaxially integrated with each other around the rotation support shaft 30 (image forming unit).

Symmetrical front and rear drums formed in a U shape and integrally connected in a state in which the rotary support shaft 30 supports a unit in which the photosensitive drum 10 and each exposure optical system 12 are integrated. Bearings are supported between the support plates 40.

The drum support plate 40 is provided with rail members 50 as suspending means at front and rear connecting portions, and the rail members 50 are inserted into and engaged with a guide member 60 provided in the main body of the apparatus to suspend. In this state, the rotary support shaft 30 and thus the photosensitive drum 10 and the exposure optical systems 12 are placed at almost predetermined set positions.

Further, when the rotary support shaft 30 is inserted to the proper position, the shaft end portion 30B protruding from the rear drum support plate 40 from the above-mentioned suspended state is provided on the rear plate 71 as a device substrate. The shaft end portion 30A that fits in the seat 72 and projects from the front drum support plate 40 is supported by the screw member 82 that is taper-fitted to the receiving seat 81 included in the drum support substrate 80, so that the photosensitive drum 10 is provided. Is precisely regulated to a regular set position so that the gear 10G meshes with the drive-side gear, while each exposure optical system 12 further has a through pin P1 provided on the shaft end 30B formed in the seat 72. By engaging with the V-shaped groove,
It is accurately regulated at a predetermined angular position with respect to the apparatus main body, and becomes a fixed state. After that, the lead wires of each optical system are connected to each power source section from each window 20A of the support member 20 on the front surface side through the cutout section 40A of the drum support plate 40.

The drum supporting board 80 has a plurality of upper and lower reference holes H1 engaged with a pair of reference pins P2 of the front plate 70 as a front device board so that the mounting positions thereof are determined. It is fixed to the front side plate 70 by means of a screw stopper, and further the plurality of windows 80A are opened and the above-mentioned rod-shaped chargers 11 are inserted from the outside of the drum support substrate 80 to the photosensitive drum 10. On the other hand, the electrodes are set at a predetermined interval position, and the electrodes are connected and fixed by screwing to support them.

Therefore, in the drum support substrate 80, if the screw members 82 are removed while the chargers 11 are removed through the windows 80A, the front side plate 70 is simply released. More separated.

From that state, the drum support plate 40
Is pulled out by sliding the rail member 50 under the guidance of the guide member 60, and the image forming unit in which the photosensitive drum 10 and each exposure optical system 12 are integrated moves in the horizontal direction, and the front side plate 70 as an apparatus substrate is moved. It is possible to take it out of the apparatus main body from the opening 70A serving as the image forming body opening.

Prior to the start of the attachment / detachment operation of the photosensitive drum 10 supported by the drum support plate 40 to / from the main body of the apparatus, the intermediate transfer belt 14 arranged around the photosensitive drum 10 and the respective pressing action of the blades. The cleaning device 100 that has been released in advance is 1 mm to 1
The developing device 13 is in a retracted state by about 0 mm, and each of the developing devices 13 arranged around the photoconductor drum 10 can pull out the developing device 13 in the same direction as the drawing direction of the photoconductor drum 10 described later. It is assumed that it has been retracted to a certain position, and it will be returned to the pressure contact state again after mounting.

After the drum support plate 40 is detached from the main body of the apparatus, the rail member 50 is placed on the lower side as shown in FIG. 4 so that the drum support plate 40 is placed in a well-balanced manner so as not to come into contact with the floor. It also functions as a stand that can be used to protect the surface of the photoconductor.

According to FIGS. 5 and 6, each of the rollers 1 described above is
Reference numerals 4A to 14D denote each of the front and rear belt support plates 4 formed integrally in a U-shape while the intermediate transfer belt 14 is stretched by the bias of the tension roller T.
5 between the bearings.

The belt support plate 45 is further formed in a U-shape, and is connected between the asymmetrical front and rear belt support substrates 85 integrally connected to each other, and the cleaning device 14 is provided between the front and rear belt support substrates 85.
It is sandwiched with 0 and integrated.

The front belt supporting board 85 is provided with a reference hole H2 as a suspending means at the upper and lower rising portions 85A, while the rear belt supporting board 85 is also provided on the back side with a pair of reference pins P4 as suspending means. And a reference pin P provided on the front plate 70 on the front side.
On the other hand, the intermediate transfer belt 14 is set at a predetermined position by fixing the above-mentioned reference pin P4 with an upper screw engaged with a reference hole H3 provided in a rear side plate 71 as a rear device board. A first transfer area for transferring a toner image from the photosensitive drum 10 to the intermediate transfer belt 14 by pressing against the peripheral surface of the photosensitive drum 10, and further pressing the intermediate transfer belt by pressing the transfer roller 15. A second transfer area for transferring the toner image to the transfer material is formed from 14.

The belt supporting substrate 85 is the front and rear side plates 7.
0 and 71 are supported on a front side of the apparatus main body via a pair of guide rails 200 which can be extended and contracted in two steps called an accuride rail (trade name).

The belt support substrate 85 has a pair of front and rear guide plates 86 provided on the left and right sides, respectively, and vertically sandwiches the movable portion 200A of the guide rail 200 so that it can slide in the vertical direction. The movable part 200A
However, in the vertical direction, the abutting plate 87 can be lowered until it abuts against the movable portion 200A.

The belt supporting board 85 is released slightly from the front surface of the main body of the apparatus after the screws are released, and the reference pins and the reference holes are released from the engagement so that the belt supporting board 85 is slightly lowered. Therefore, when each of the abutting plates 87 is on the movable part 200A, the guide rail 200 is extended to the front side of the main body of the apparatus through the opening hole 70A of the front plate 70 serving as the image forming body opening. .
As a result, the intermediate transfer belt 14 is retracted from the peripheral surface of the photosensitive drum 10 and is pulled out in a state where the pressure contact is released. Even when the belt is re-mounted, the guide rail 200 returns from the extended state and guides the tapered portion of each reference pin. As a result, the photosensitive drum 10 is slightly moved upward, and the operation of returning to the state of being pressed against the photosensitive drum 10 is automatically and reliably performed.

Therefore, the photosensitive drum 10 is moved to the intermediate transfer belt 14 by an extremely simple attachment / detachment operation of the belt supporting substrate 85.
It is possible to remove the jammed paper remaining in the conveyance path by pulling out the belt support substrate 85, and to easily perform maintenance such as replacement and inspection of the intermediate transfer belt 14 without interfering with the belt support substrate 85.

The belt supporting substrate 85 is previously released from the pressure contact action of the transfer roller with the roller 14C for stretching the intermediate transfer belt 14 prior to the operation of pulling out from the apparatus main body, and is returned to the predetermined set position again. It is put in pressure contact.

The attachment / detachment of the developing means to / from the apparatus main body will be described with reference to FIGS. 7, 8 and 1. FIG. 7 is a view showing a mounting state of the developing unit, and FIG. 8 is a view showing an opening of the device substrate.

As shown in FIG. 7, the photosensitive drum 10 has flange members 10B and 10A (not shown) at both ends which are held by a rotary support shaft 30 which is fixed to a rear side plate 40 via bearings B. Is rotatably supported by the supporting member 20 of each of the flange members 10B and 1B at both ends of the photosensitive drum 10.
The flange member 1 is provided with stopper portions 101B and 101A (not shown) as stop means at the time of press-fitting 0A (not shown).
0B and 10A (not shown) are press-fitted, and the flange member 10
The photosensitive drum 10 is held by B and 10A (not shown).

Each developing device 13 is in the direction of the central axis of the photosensitive drum 10 shown by the dotted arrow in FIG. 7 and is orthogonal to the drawing direction of the photosensitive drum 10 from the retracted position in the direction shown by the solid arrow in FIG. For example, the thickness is 3 mm and the outer diameter is 20 as a gap holding unit that is moved and brought into contact with the photosensitive drum 10.
The developing sleeve 130 and the photoconductor drum 10 have a predetermined gap, for example, 1
Each developing device 13 is mounted while keeping a non-contact state with a gap of 00 μm to 1000 μm.

On the rear surface of the drum 40, a drive motor M1 for driving the gear 10G and its power transmission means, that is, a drive system G for the gear 10G are provided on the back surface thereof.
(T) is attached and supported, and the photosensitive drum 10 is rotated by the drive of the drive system G (T). Gear 10G provided on photoconductor drum 10 and at least gear 10G
The final gear G1 of the drive system G (T) coupled to the drive gear G1 is constituted by a helical gear, and the photosensitive drum 10 is pressed in the direction of the arrow during rotation, and the flange members 10B and 10A (not shown) and the support members 20 at both ends are formed. The play of the bearing B fitted in and is absorbed in the thrust direction, and the bearing B is rotated while being pressed in one direction.
This prevents displacement of the exposure light between the exposure optical systems on the image forming body, which is caused by the play of the bearings B at both ends, and provides a good superimposed color toner image with highly accurate registration. It is formed.

Further, the developing sleeve 130 is the gear 10 provided on the flange member 10B on the rear side of the photosensitive drum 10.
It is rotationally driven by a gear (not shown) coupled to G. The abutting roller 131 is driven to rotate by the rotation of the photosensitive drum 10.

As described above, the developing devices 13 arranged around the photosensitive drum 10 are retracted to a position of about 30 mm to 50 mm in a substantially horizontal direction orthogonal to the drawing direction of the photosensitive drum 10. However, as shown in FIG. 8, from the retracted position, each developing device 13 is exposed substantially horizontally through the Y, M, C, and K opening holes 70B as the developing means opening portions provided in the front side plate 70 as the device substrate. The body drum 10 can be withdrawn in the same direction as the withdrawal direction. The front side plate 70 as a device substrate is made of an iron steel plate having a plate thickness of approximately 1.2 mm to 3 mm. If the plate thickness is less than 1.2 mm, it is difficult to maintain the strength as a side plate, and if it exceeds 3 mm, it becomes difficult to process the side plate such as punching, bending and drawing.

Opening hole 70 for pulling out the photosensitive drum 10
The closest distance between the cutout end portion of A and the opening hole 70B of the developing device 13 is at least 5 m depending on the plate thickness of the front plate 70.
Since they are formed in a state of being separated from each other by m to 30 mm or more, the strength around the opening hole 70A as the image forming member opening is maintained. For a plate thickness of 3 mm, an interval of 5 mm or more,
For a plate thickness of 1.2 mm, it is preferable to have an interval of 30 mm or more.

Since the opening hole for pulling out the photosensitive drum and the opening hole for the developing device are formed in a state of being separated from each other, the surroundings of the opening hole for pulling out the photosensitive drum provided on the front side plate as the device substrate. Of the image exposure light is less likely to occur due to uneven driving during the driving of the image forming body. Further, the developing means can be pulled out in the same direction as the image forming body while maintaining the strength around the opening of the image forming body.

Further, the developing means opening is not provided in the front plate 70 as the device substrate, and as shown by the arrow in FIG. 1, each developing device 13 is orthogonal to the central axis of the photosensitive drum 10 as the image forming body. By attaching and detaching from the retracted position in the direction,
The strength around the image forming body opening can be further increased.

[0064]

According to the first aspect of the present invention, the intensity around the opening of the image forming body of the color image forming apparatus is maintained, and the image exposure light from the plurality of image exposing means due to the uneven driving when the image forming body is driven. It is unlikely that there will be misalignment.

According to the second aspect, the developing means can be pulled out in the same direction as the image forming body while the strength around the opening of the image forming body is maintained.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus.

FIG. 2 is a front view showing a support structure of the image forming body.

FIG. 3 is a sectional view showing a support structure of the image forming body.

FIG. 4 is an external view of an image forming unit.

FIG. 5 is a front view showing a support structure of the intermediate transfer belt.

FIG. 6 is a cross-sectional view illustrating a support structure of the intermediate transfer belt.

FIG. 7 is a diagram illustrating a mounting state of a developing unit.

FIG. 8 is a view showing an opening of a device substrate.

[Explanation of symbols]

 10 Photoreceptor Drums 10A, 10B Flange Member 11 Charging Device 12 Exposure Optical System 13 Developing Device 20 Supporting Member 30 Rotating Support Shaft 40 Drum Support Plate 70 Front Side Plate 70A, 70B Opening Hole 71 Rear Side Plate 130 Developing Sleeve 131 131 Abutting Roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayasu Onodera 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Satoshi Haneda 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Toshihide Miura 5-14-14, Midoricho, Koganei-shi, Tokyo

Claims (2)

[Claims] 1. A plurality of sets of charging means, image exposing means, and developing means are arranged around a rotating image forming body, and the charging means is attached to the image forming body during one rotation of the image forming body. The toner image is formed by sequentially charging the toner image, exposing the image by the image exposing unit, and developing the toner image by the developing unit, thereby superposing a plurality of toner images on the image forming body, and then forming the superposed toner images. In a color image forming apparatus for collectively transferring to a transfer material, an image of an apparatus substrate provided in the color image forming apparatus, wherein the plurality of sets of image exposing means and the image forming body are integrated into one unit. The color image forming apparatus is capable of being drawn out substantially horizontally from the center of the image forming body through the opening of the forming body, and the plurality of developing means are arranged in a direction orthogonal to the drawing direction of the image forming body. Color image forming apparatus is characterized in that a retractable to a position apart from Kizo former. 2. The developing means passes through a developing means opening portion of a device substrate provided in the color image forming apparatus at a retracted position in the same direction as the drawing direction of the image forming body and apart from the image forming body opening portion. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is provided so as to be drawn out from the color image forming apparatus.