JPH11167235A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent color slippage from occurring on a toner image being laid over the other, in consequence of the irregular rotation of the image forming body or a developing sleeve. SOLUTION: As for this device, while a gear wheel 10G on a photoreceptor drum 10 is allowed to move respectively corresponding to gear wheels N1, N2 and N3 opposing between respective exposing optical system 12, the rotation of the developing sleeve gear wheel 130G driven by the driving gear wheel G2 with a different driving source through the idle gear wheel 13G is, transmitted to the developing sleeve 130 by the work of an electromagnetic clutch in accordance with the developing timing, and the developing sleeve 130 is respectively rotated for the integral number of rounds by the drive of the driving gear wheel G1. In such a manner, the device is made so that the transfer irregularity occurs in a specific position by specifying the image exposure surface on the developing sleeve 130 and the photoreceptor drum 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum-shaped image forming body, on which a plurality of charging, image exposing, and developing means are arranged so that toner is applied to the image forming body during one rotation of the image forming body. The present invention relates to an electrophotographic color image forming apparatus that is formed by superimposing the color images.

[0002]

2. Description of the Related Art As a method of forming a multicolor image, a photoconductor, a charger, a developing device and the like are provided in the same number as required for the image. Apparatus for superimposing a color image on a body (A)
Or an apparatus (B) for forming a color image by repeating charging, image exposure and development for each color by rotating one photoconductor a plurality of times, or charging and image exposure for each color within one rotation of one photoconductor An apparatus (C) for forming a color image by sequentially performing development is known.

However, the above-mentioned apparatus (A) has a disadvantage that the capacity of the apparatus is increased because a plurality of photoconductors and intermediate transfer bodies are required, while the apparatus (B) has only one charging means, image exposure means and photoconductor. Although only one is used, the volume is reduced, but there is a restriction that the size of the formed image is limited to the surface area of the photoconductor or less.

On the other hand, the apparatus (C) is excellent in that the image size is not restricted and high-speed image formation can be realized.

[0005]

However, in the apparatus (C), if the driving side gear for transmitting the driving force of the motor to the image forming body has a pitch unevenness or a variation in the meshing depth, the motor is not fixed. Even if it rotates at high speed, the transmission speed changes periodically and the peripheral speed of the image forming body becomes uneven, so the registration of the superimposed image fluctuates,
There is a problem that color misregistration occurs and image quality remarkably deteriorates.

[0006] Such a problem also causes a deterioration in image quality due to color misregistration even when the peripheral speed of the driving gear of the developing sleeve of the developing device fluctuates due to eccentricity or uneven pitch.

The present invention has solved and improved the above points,
It is an object of the present invention to provide a color image forming apparatus capable of recording images of high quality without color misregistration with high accuracy even when the transmission speed of a driving gear may periodically change. It was done.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to dispose a plurality of charging means, image exposing means and developing means in the vicinity of the peripheral surface of an image forming body, and charge and image exposing during one rotation of the image forming body. A color image forming apparatus that forms a color toner image by superimposing a plurality of toner images on a peripheral surface of the image forming body, wherein the image forming body is a drum-shaped image forming body, The gear that rotates integrally with the formed body is driven and rotated independently of the gear provided on the developing sleeve shaft of the developing unit, and the gear provided on the developing sleeve shaft is:
A color image forming apparatus (the invention according to claim 1), wherein the gear provided on the image forming body side rotates an integer number of times between the respective image exposing means for the movement of the gear corresponding to the respective image exposing means; A plurality of charging means, an image exposing means, and a developing means are disposed in the vicinity of the peripheral surface of the image forming body, and charging, image exposing and developing are repeated during one rotation of the image forming body, In a color image forming apparatus that forms a color toner image by superimposing a plurality of toner images, the image forming body is a drum-shaped image forming body, and a gear that rotates integrally with the image forming body includes: The gears are driven and rotated independently of gears provided on a developing sleeve shaft of the developing means, and each of the gears is a helical gear, and applies a thrust in a certain direction to the image forming body with the driving rotation. Color image forming apparatus (claim Is achieved by according the invention) to.

[0009]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and 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 the 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 sectional view showing a support structure of the photosensitive drum, FIG. 3 is a sectional view showing a support structure of the photosensitive drum, FIG. 4 is an external view of a drum unit, and FIG.
FIG. 6 is a front sectional view showing a support structure of the intermediate transfer belt, and FIG. 6 is a sectional view showing a support structure of the intermediate transfer belt.

A photosensitive drum 1 which is a drum-shaped image forming body
Reference numeral 0 denotes, for example, a cylindrical transparent resin substrate formed by a transparent member of a transparent acrylic resin provided inside, and a transparent conductive layer and an organic photoconductor layer (OPC) formed on the outer periphery of the substrate. It is rotated in the direction shown by the arrow in FIG.

In the present embodiment, it is sufficient that the photoconductive layer of the photosensitive drum has an exposure light amount capable of giving 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. Also,
It may be colored as long as it has a property of transmitting the exposure light. The refractive index of these resins is approximately 1.5. As a method of forming the light-transmitting conductive layer, indium tin oxide (ITO), alumina, tin oxide, lead oxide, and the like can be used by vacuum evaporation, active reaction evaporation, various sputtering methods, and various CVD methods. Indium oxide, copper iodide, Au, A
A light-transmissive thin film made of g, Ni, Al, or the like is used, or a conductive resin made of the above-described metal fine particles and a binder resin by a dip coating method, a spray coating method, or the like is used. Various organic photoconductor layers (OPC) can be used as the photoconductor layer.

Examples of preferred image forming members are shown below.

After adding a catalyst for synthesizing and polymerizing the plastic material monomer, pouring it into a cylindrical mold, sealing and fixing with a side plate, rotating this at a high speed and heating it appropriately 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 of a transparent resin substrate of a transparent plastic molded by centrifugal polymerization, a material obtained by polymerizing a methacrylic acid methyl ester monomer as described above is the best in terms of transparency, strength, precision, surface properties and the like. And other polyethyl methacrylate, polybutyl methacrylate, polyethyl acrylate, polybutyl acrylate, polystyrene, polyimide, polyester, polyvinyl chloride, and the like, or a copolymer thereof, and the like. In the centrifugal polymerization method, since the roundness is determined by the mold used for molding, a highly accurate substrate can be obtained.

As the conductive layer, conductive fine particles made of indium tin oxide (ITO), tin oxide, lead oxide, indium oxide, alumina, copper iodide, Au, Ag, Ni, Al, etc., and resin are used. Is used, and as a film forming method, a dip coating method, a spray coating method, or the like is preferably used.

The organic photoreceptor layer comprises a charge generating material (CGM)
And a charge transport layer (CTL) containing a charge transport material (CTM) as a main component. The organic photoreceptor layer having a two-layer structure has a low CGL, and thus has good transparency of image exposure light and is suitable for the present invention. The organic photoreceptor layer may have a single-layer structure containing a charge generation material (CGM) and a charge transport material (CTM) in one layer, and may have the single-layer structure or the two-layer structure. Usually contains a binder resin.

In the photosensitive drum having the two-layered organic photosensitive layer, the CGM contained in the CGL may be an azo pigment, an azulenium pigment, a phthalocyanine pigment which is sensitive to light from a light source such as an LED or an LD. , A perylene pigment is used, and red to infrared light (600 nm
Copper phthalocyanine pigments, titanyl phthalocyanine pigments, and the like are preferably used as the CGM of the OPC photoreceptor that is sensitive to light of about 850 nm.

As the binder resin used for CGL, a polyvinyl butyral resin or a polycarbonate resin is used, which is excellent in sensitivity, potential change upon repeated use, and the like. These binder resins can be used alone or as a mixture of two or more.

As a solvent or a dispersion medium used for forming CGL, a ketone-based or halogen-based solvent is preferably used, and the sensitivity and the potential change upon repeated use are further improved. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.

The weight ratio of CGM to the binder resin in the CGL is 100: 1 to 1000, the thickness of the CGL is 0.01 to 10 μm, and the coating method for forming the CGL is a blade. There are various coating methods such as coating, wire bar coating, spray coating, dip coating and slide hopper coating.

Next, as the CTM contained in the CTL, hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds and the like are used.

As the binder resin used in the CTL, a wide range of insulating resins can be appropriately selected and used, and preferred binder resins are silicon-alkyd resin, phenol-formaldehyde resin, poly-N- Insulating resins such as vinyl carbazole and polysilane can be mentioned, and these binder resins can be used alone or in combination of two or more.

The mixing ratio of the binder resin and CTM is 1:
It is set to 10 to 500, and more preferably 1:20 to 150. The thickness of the CTL is set to 1: 100 μm.
~ 50 μm is preferred.

As a coating method, a method similar to CGL can be used.

If necessary, an intermediate layer is provided between the organic photoreceptor layer and the conductive layer. Examples of the intermediate layer include polyvinyl chloride vinyl acetate copolymer, vinyl acetate vinyl acetate maleate copolymer, ethyl cellulose and carboxymethyl cellulose. And a resin layer having a thickness of 0.01 to 2 μm, such as a copolymer type or modified type alcohol-soluble polyamide resin.

By using the plastic cylindrical transparent resin substrate produced by the above-described manufacturing method, the thickness is uniform, the cylindrical substrate has excellent cylindricity and roundness, and the image exposure light is defocused. The present invention provides a photoreceptor drum free of defects.

Numeral 11 denotes a scorotron charger (hereinafter simply referred to as a charger) which performs a charging action on the above-mentioned organic photoreceptor layer of the photoreceptor drum 10 by a grid maintained at a predetermined potential and corona discharge by a discharge wire. A uniform potential is applied to the photosensitive drum 10.

Reference numeral 12 denotes an exposure optical system comprising image exposure means, that is, LEDs arranged in the axial direction of the photosensitive drum 10 and a selfoc lens which is a unity-magnification imaging system, which is read by a separate image reading device. The image signals of the respective colors are sequentially taken out of the memory and input to the respective exposure optical systems 12 as electric signals.

Each of the exposure optical systems 12 is attached to a support member 20 provided as an optical system support means, and is housed inside the substrate of the photosensitive drum 10.

Reference numerals 13Y to 13K denote developing units for accommodating yellow (Y), magenta (M), cyan (C) and black (K) developers, each having 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 while maintaining the same.

Each of the developing units 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 charger 11 and the image exposure by the exposure optical system 12. To reverse development.

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

At the start of image recording, the photosensitive drum 10 is rotated counterclockwise by the start of the photosensitive member drive motor, and at the same time, the 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, the exposure optical system 12 (Y) starts exposure with an electric signal corresponding to a first color signal, that is, an image signal of yellow (Y). 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) in a state where the developer on the developing sleeve is not in contact, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further provided with a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second potential of the exposure optical system 12 (M) is changed.
Exposure is performed using an electric signal corresponding to the color signal of magenta (M), that is, the image signal of magenta (M), and the magenta (M) ) Are sequentially formed to be superimposed.

By the same process, the charger 11 (C),
The exposure optical system 12 (C) and the developing device 13 (C) further form a cyan (C) toner image corresponding to the third color signal.
Further, a black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the charger 11 (K), the exposure optical system 12 (K), and the developing device 13 (K). Within one rotation, a color toner image is formed on the peripheral surface.

The photosensitive drum 1 by 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 is equivalent to the image corresponding to the first color signal. It is possible to form an electrostatic latent image. Each exposure optical system 12
In order to stabilize the temperature in the photoconductor drum 10 and prevent the temperature from rising due to the heat generated by the above, a material having good thermal conductivity is used for the support member 20, a heater is used at low temperatures, and a heat pipe is used at high temperatures. By taking measures such as dissipating heat to the outside through the device, it can be suppressed to a level where there is no problem. In the developing operation of 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, and 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 an intermediate transfer means.

The intermediate transfer belt 14 has a thickness of 0.5 to 2.0.
mm, a semiconductive substrate of silicon rubber or urethane rubber having a resistance of 10 ⁸ to 10 ¹² Ω · cm, and a thickness of 5 to 50 μm as a toner filming prevention layer on the outside of the rubber substrate. And a two-layer structure with fluorine coating. This layer also preferably has a similar semiconductivity. 0.1-0.5m thickness instead of rubber belt base
m, a semiconductive polyester, polystyrene, polyethylene, polyethylene terephthalate, or the like can also be used. The intermediate transfer belt 14 has rollers 14A, 14B,
The photosensitive drum 10 is stretched between the rollers 14C and 14D, and is circulated clockwise 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, to form a toner image transfer area at each contact point. ing.

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 the 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 guidance of the grounded roller 14A,
The intermediate transfer belt 14 is applied by applying a bias voltage of kV.
It is efficiently transferred to the 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 synchronized with the transport 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 of the opposite polarity to the toner of 1 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, and sandwiched and conveyed between the heat roller 91A and the pressure roller 91B to be heated. After the toner is fused and fixed, the toner is discharged to the outside of the apparatus via a discharge roller 92.

The photosensitive drum 10 and the intermediate transfer belt 14 have cleaning devices 100 and 14 respectively.
No. 0 is provided, and the blades provided are always in pressure contact with each other, the remaining adhered toner is removed, and the peripheral surface is always kept in a clean state.

The support member 20 comprises a pair of front and rear members fixed to a rotation support shaft 30 of the photosensitive drum 10 as shown in FIGS.
2 has both ends adjusted so that the distance to the photosensitive surface via the attaching member 21 is in a predetermined positional relationship, and is fixed to the adjustment position by bonding.

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

The rotation support shaft 30 is connected to the photosensitive drum 10
Each of the symmetrical front and rear side plates 40 formed in a U-shape and integrally connected while supporting each of the exposure optical systems 12.
The bearing is supported between.

The side plate 40 is provided with rail members 50 as hanging means at front and rear connecting portions, and the rail members 50 are inserted into and engaged with guide members 60 provided in the apparatus main body to be in a suspended state. By doing so, the rotation support shaft 30, and thus the photosensitive drum 10 and each of the exposure optical systems 12 are placed at substantially predetermined positions.

Further, when the rotation support shaft 30 is inserted to a proper position, the shaft end 30B protruding from the rear side plate 40 from the above-mentioned suspended state is fitted to the receiving seat 71 provided on the apparatus board. Shaft end 30 protruding from front side plate 40
A is supported by a screw member 82 which is tapered into a receiving seat 81 provided on a support substrate 80, thereby accurately regulating the photosensitive drum 10 to a regular set position and meshing the gear 10G with the driving gear. On the other hand, each exposure optical system 12 is further engaged with the through-pin P1 provided on the shaft end 30B in the V-shaped groove formed in the receiving seat 71, so that a predetermined angle with respect to the apparatus main body is obtained. The position is accurately regulated and becomes a fixed state. Thereafter, the lead wires of the respective optical systems are connected from the respective windows 20A of the support member 20 on the front side to the power supply unit through the cutouts 40A of the side plate 40.

The support substrate 80 is provided with upper and lower reference holes H.
1 engages with a pair of reference pins P2 provided on the front device board 70, determines the mounting position thereof, and is fixed to the front device board 70 by a plurality of screwing screws. Each of the rod-shaped chargers 11 having the window 80A opened and having the above-described rod shape is inserted from the outside of the support substrate 80 to be set at a predetermined interval position with respect to the photoconductor drum 10, and a screwing screw is set in a state where the electrodes are connected. It is fixed and supported by.

Therefore, the support substrate 80 is provided with each charger 1
When the screw member 82 is removed in a state where 1 is removed through the window 80A, the screw member 82 is only released from a plurality of screw holes, and is separated from the device substrate 70. From this state, the side plate 40 is removed. The rail member 50 is slid under the guidance of the guide member 60 so that the photosensitive drum 10 and each of the exposure optical systems 12 are integrally moved in the horizontal direction, and can be taken out of the apparatus main body through the opening 70A of the apparatus substrate 70. Becomes

Prior to the start of the attaching / detaching operation of the photosensitive drum 10 supported by the side plate 40 to / from the apparatus main body, each developing device 13, the intermediate transfer belt 14, and the cleaning device 100 with respect to the peripheral surface of the photosensitive drum 10. Each pressing action of the blade is released in advance, and the blade is in a retracted state of about 1 to 10 mm, and is returned to the pressed state again after mounting.

After the side plate 40 has been removed from the apparatus main body, the rail member 50 can be placed on the lower side as shown in FIG. 4 so that the photosensitive drum and the like can be placed in a well-balanced manner so as not to contact the floor surface. Function as a table,
It is also used to protect the photoreceptor surface.

Each of the rollers 14A to 14D is formed in a U-shape in a state where the intermediate transfer belt 14 is stretched by the urging force of the tension roller T, and the front and rear side plates 45 are integrally connected. Bearings are supported between them.

The side plate 45 is formed in a U-shape and sandwiched together with the cleaning device 140 between the asymmetrical front and rear support substrates 85 which are integrally connected to each other to be integrated.

The front support substrate 85 has a reference hole H2 as a suspending means at the upper and lower rising portions 85A, while the rear support substrate 85 has a pair of reference pins P4 as the suspending means at the back. The reference hole H
2 has a reference pin P3 provided on the front device board 70, and a reference hole H having the reference pin P4 provided on the rear device board.
The intermediate transfer belt 14 is set at a predetermined position by screwing and fixing the upper screw engaged with the photosensitive drum 1 and the photosensitive drum 1.
0 to form a first transfer area for transferring a toner image from the photosensitive drum 10 to the intermediate transfer belt 14 by pressing the transfer material from the intermediate transfer belt 14 by pressing the transfer roller 15. For transferring the toner image to the second
Is formed.

The support substrate 85 is provided between the front and rear device substrates 70.
On the other hand, it is supported so as to be able to be pulled out to the 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 support substrate 85 is formed by a pair of front and rear guide plates 86 provided on the left and right sides, respectively.
The movable part 200A is slidably held in the vertical direction, and the movable part 200A is integrated in the pulling-out direction.
It is configured to be able to descend until it hits 00A.

The above-mentioned support substrate 85 is released from engagement with the above-described reference pins and the respective reference holes by slightly pulling out the screw holes and slightly pulling out to the entire surface of the apparatus main body. Therefore, when the respective abutment plates 87 are mounted on the movable portions 200A, the guide rails 200 are extended to the front of the apparatus main body from the openings 70A of the apparatus substrate 70 by the extension operation of the guide rails 200. As a result, the intermediate transfer belt 14
The guide rail 200 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 guide rail 200 is mounted again, the guide rail 200 is returned from the extended state and is slightly moved upward by the guide of the tapered portion of each reference pin. Move to the photosensitive drum 10
The operation of returning to the pressure-contact state is automatically and reliably performed.

Accordingly, the photosensitive drum 10 can be taken out without interfering with the intermediate transfer belt 14 by a very simple attaching / detaching operation of the support substrate 85. Further, the jammed paper staying in the conveyance path by pulling out the support substrate 85 can be removed. Maintenance such as removal processing, replacement of the intermediate transfer belt 14, and inspection can be easily performed.

Prior to the operation of pulling out the support substrate 85 from the apparatus main body, the pressing action of the transfer roller against the roller 14C for stretching the intermediate transfer belt 14 is released in advance, and after returning to the predetermined set position, the press contact is performed again. Placed in state.

As shown in FIG. 7, the photosensitive drum 10 is rotated by the power of a driving gear G1 meshing with a gear 10G of the flange member 10B. On the other hand, the developing sleeve 130 of each of the developing devices 13 is integrated with the developing sleeve 130 by the power of the driving gear G2 having a power source different from that of the driving gear G1 via the idle gear 13G coaxial with the photosensitive drum 10. The transmission is transmitted to the sleeve gear 130G, and is further driven by the operation of an electromagnetic clutch CL provided between the drive transmission systems in accordance with the development timing.

In this configuration, the photosensitive drum 10
The gear 10G is integrated with the flange member 10B. The gear 10G and the photosensitive drum 10 rotate integrally when driven, but the photosensitive drum 1
It is also possible to adopt a configuration in which only 0 is taken out.

(Embodiment 1) An embodiment of the invention according to claim 1 will be described with reference to FIGS.

The above-mentioned sleeve gear 130G is an integer while the gear 10G of the photosensitive drum 10 moves the number of teeth corresponding to each exposure optical system 12, ie, the number of teeth N1, N2 and N3 shown in FIG. It is configured to rotate each time.

That is, the photosensitive drum and each developing unit 13
Each drive system is constituted by a gear train composed of gears of the same module. Each of the gears 130G has the number of teeth No. and the gear 1 provided on the photosensitive drum 10.
Each tooth number N corresponding to the angle between each of the exposure optical systems 12 of 0G
1, N2 and N3 are equal or an integer multiple, that is, in the case of the present embodiment, each of the tooth numbers N1, N2 and N3 is equal to or equal to the tooth number No. The relationship between the number of teeth of the gear 130G provided on the developing sleeve 130 and the positional relationship of each exposure optical system 12 on the peripheral surface of the photosensitive drum 10 is set so as to have an integer ratio.

The gear 10G provided on the photosensitive drum 10 has a total number of teeth that is an integral multiple of each of the numbers N1, N2 and N3 indicating the positional relationship of the exposure optical system 12. Therefore, the gears 130G provided on each of the developing sleeves 130 are set to have an integer ratio of the number of teeth No.

Further, the number of teeth of the gear G1 is
, The total number of teeth of the gear 10G becomes an integral multiple of the number of teeth of the driving gear G1. As a result, the driving gear G1 has a tooth-shaped pitch error or eccentricity. In this case, the rotation unevenness of the gear 10G transmitted by the rotation is caused by the gear 10G, that is, the photosensitive drum 1 as shown in FIG.
0, which occurs in a fixed phase relationship of each rotation cycle. Therefore, exposure of each image by each exposure optical system 12 is performed by superposing under the condition of the same peripheral speed of the photosensitive drum 10 to perform image exposure. As a result, the accuracy of the so-called image registration can be improved, and no deviation (color deviation) occurs between the superimposed toner images.

The rotation unevenness is transmitted to each of the developing sleeves 130 via the drive gear G2 or the idle gear 13G. Each developing sleeve 130 is rotated in accordance with the moving speed of the image on the drum surface. As a result, the peripheral speed of the photosensitive drum 10 and the peripheral speed of each developing sleeve 130 are set to be substantially equal using one-component developer. Even in the image forming apparatus of the present embodiment, a high quality toner image without development unevenness can be developed.

The gear 10G has a rotation supporting shaft 3 for stably maintaining the rotation speed of the photosensitive drum 10.
It is preferable to provide a flywheel on the flywheel 0 in order to increase the coefficient of inertia. In this case, the gear 10G may be formed on the peripheral surface of the flywheel and directly driven and rotated by the gear G1.

(Embodiment 2) An embodiment of the invention according to claim 6 will be described with reference to FIG.

The photosensitive drum 10 is rotated in the direction of arrow B by the power of the driving gear G1 that rotates in the direction of arrow A and directly meshes with the gear 10G in a fixed relationship with the flange member 10B. . On the other hand, each of the developing sleeves 130 is connected to the coaxial sleeve gear 130G connected via the electromagnetic clutch CL via the electromagnetic clutch CL by the power of the drive gear G2 meshed via the idle gear 13G. Rotated in the direction.

Each of the above-mentioned gears is constituted by a helical gear, and is provided at each shaft end on the back side of the apparatus.
And the driving gear G2 are helical gears having a helical angle of a left direction, and the gear 10G and the gear 130G meshing with each other are helical gears having a helical angle of a right direction. On the body drum 10,
Further, the driving power of the driving gear G2 is smoothly transmitted to the gear 130G, that is, the developing sleeve 130, without vibration due to meshing between the teeth.

Further, in transmitting the drive, the power of the drive gear G1 is determined by the helical angle of the helical gear.
In addition to the rotational force acting on the photosensitive drum 10 toward the rear side of the apparatus main body by applying a thrust in the direction of the arrow F1 together with the rotational force to the drive gear G2, the rotational force of the drive gear G2 is controlled by the helical gear. The helical angle acts on the sleeve gear 130G together with the rotational force and the thrust in the direction indicated by the arrow F1 to urge the developing sleeve 130 in the same direction as the photosensitive drum 10 toward the rear side of the apparatus.

As a result, at the time of image formation, the above-described penetrating pin P1
Is firmly pressed against the V-shaped groove of the receiving seat 71, the positions of the exposure optical systems 12 in the angular direction and the positions of the developing sleeves 130 in the axial direction are determined. Photoreceptor drum 10
Also, the axial position is regulated and the image forming area is stabilized,
Asobi of the image exposure position in the main scanning direction by each image exposure optical system 12 is removed, and a deviation in the scanning direction between the superimposed images is eliminated, so that a color image without color deviation is obtained.

It is preferable to provide a flywheel on the rotation support shaft 30 to stably maintain the rotation speed of the gear 10G, that is, the photosensitive drum 10, in order to increase the inertia performance.

In each of the embodiments described above, the color image forming apparatus in which the image exposing means is arranged inside the image forming body has been described. However, in any of the present invention, the image exposing means is arranged on the outer periphery of the image forming body. The same effect can be obtained even when the present invention is applied to a color image forming apparatus in which image exposure is performed from the outside.

[0081]

According to the present invention, a plurality of developing means provided in a color image forming apparatus can be efficiently driven at a constant speed by a power of an image forming body through a very simple gear device. By means of (5), even if the rotation of the image forming body or the developing sleeve is uneven, registration of the image exposure and development timing of each toner image is guaranteed, and the color shift between the toner images is eliminated. Claim 6
Through the steps (8) to (8), the image forming body and the image exposing means are secured at regulated positions at which respective images can be formed at the time of image forming, and color shift in the main scanning direction is eliminated.

As a result, a highly practical color image forming apparatus capable of forming a high-quality color image with a simple mechanism is provided.

[Brief description of the drawings]

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

FIG. 2 is a front sectional view showing a support structure of a photosensitive drum.

FIG. 3 is a cross-sectional view illustrating a support structure of a photosensitive drum.

FIG. 4 is an external view of a drum unit.

FIG. 5 is a front sectional 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 main part configuration diagram showing positions of a developing device and an exposure optical system.

FIG. 8 is a diagram showing a position where uneven feeding occurs in the first embodiment.

FIG. 9 is an explanatory view showing a gear mechanism of the developing device.

[Explanation of symbols]

 Reference Signs List 10 photoreceptor drum 10A, 10B flange member 11 charger 12 exposure optical system 13 developing device 14 intermediate transfer belt 15 transfer roller 20 support member 30 rotation support shaft 40 (drum) side plate 70 (device) substrate 71 (rotation support shaft) Seat 130 Developing sleeve 10G (Drum) gear 130G (Developing sleeve) gear G1 (Drum) driving gear G2 (Developing sleeve) driving gear

Claims (8)

[Claims] A plurality of charging means near a peripheral surface of the image forming body;
An image exposing unit and a developing unit are provided, and charging, image exposing and developing are repeated during one rotation of the image forming body, and a plurality of toner images are superimposed on the peripheral surface of the image forming body to form a color toner image. In the color image forming apparatus, the image forming body is a drum-shaped image forming body, and a gear that rotates integrally with the image forming body is independent of a gear provided on a developing sleeve shaft of the developing unit. And the gear provided on the developing sleeve shaft rotates an integral number of times between the respective image exposing means with respect to the movement of the gear corresponding to each of the image exposing means of the gear provided on the image forming body side. A color image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the number of gear teeth provided on the image forming body between the respective image exposing means is an integral multiple of the number of gear teeth provided on the developing sleeve shaft. Color image forming apparatus. 3. The color image forming apparatus according to claim 1, wherein the number of gear teeth provided on the image forming body is an integral multiple of the number of gear teeth provided on the developing sleeve shaft. 4. The image forming apparatus according to claim 1, wherein the number of teeth of the gear provided on the image forming body is an integral multiple of the number of gears corresponding to each of the gears provided on the image forming body between the respective image exposing means. The color image forming apparatus as described in the above. 5. The image forming apparatus according to claim 1, wherein the number of teeth of a driving gear for driving the image forming member meshing with a gear provided on the image forming member is the same as the number of teeth of a gear provided on the developing sleeve shaft. The color image forming apparatus according to claim 1. 6. A plurality of charging means near the peripheral surface of the image forming body,
An image exposing unit and a developing unit are provided, and charging, image exposing and developing are repeated during one rotation of the image forming body, and a plurality of toner images are superimposed on the peripheral surface of the image forming body to form a color toner image. In the color image forming apparatus, the image forming body is a drum-shaped image forming body, and a gear that rotates integrally with the image forming body is independent of a gear provided on a developing sleeve shaft of the developing unit. Wherein each of the gears is a helical gear, and applies a thrust in a certain direction to the image forming body with the driving rotation. 7. A drive gear which meshes with a gear provided on a shaft of the image forming body and the developing sleeve and drives the gear is a helical gear. The color image forming apparatus according to claim 6, wherein 8. The color image according to claim 6, wherein a gear provided on the image forming body and a gear provided on each of the developing sleeve shafts are provided at an end of the image forming body on an inner side of the apparatus. Forming equipment.