JPH0876543A - Color image forming device - Google Patents

Abstract

PURPOSE: To provide a color image forming device capable of forming a color image whose length is equal to or exceeding the circumferential length of an image forming body and whose color is well-balanced, having a comparatively compact constitution and capable of easily loading/unloading an image exposure means. CONSTITUTION: One electrostatic charger 5C is installed nearly right above the image forming body 2, two electrostatic chargers 5M and 5K and four developing devices 6Y, 6M, 6C and 6K are set symmetrically to a vertical line passing through the center of the image forming body, and the electrostatic chargers 5M and 5K are respectively installed between the upper and lower developing devices on right and left sides, the lower developing devices 6Y and 6K are installed near the central level of the image forming body, a cleaning device 4 is installed on the downstream side away from the right underneath of the image forming body, one remaining electrostatic charger 5Y is installed between the cleaning device and the developing device installed on the downstream side of the cleaning device, a transfer means 14 is arranged on the upstream side away from the right underneath of the image forming body 2, two stirring means of the lower developing devices 6Y and 6K are arranged vertically, on the other hand, two stirring means of the upper developing devices 6M and 6C, are arranged horizontally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a cleaning device, four pairs of chargers and developing devices, and a transfer means on the outer periphery of a rotating drum-shaped image forming body, and four cleaning devices are provided inside. The present invention relates to a color image forming apparatus which is provided with an image exposing means and which transfers a color image formed by superposing toner images of different colors formed by repeating charging, image exposure and development on an image forming body to a transfer material to fix it. .

[0002]

2. Description of the Related Art The above-described color image forming apparatus can form a color image having a length equal to or longer than the circumference of the image forming body, and the image exposure of the second and subsequent colors can be hindered by the previously formed toner image. JP-A-5-307307 discloses a color image forming apparatus capable of forming a color image having a good color balance by being incident on an image forming body similarly to the first color image exposure. However, in the color image forming apparatus described in this publication, only four pairs of the charging device and the developing device are provided on the outer side of the drum-shaped image forming body, so that the device cannot be downsized sufficiently.
Since four image exposing means are fixedly provided inside the image forming body, the structure becomes complicated, and it takes time to attach and detach the image forming body and the image exposing means, and the positional accuracy between each equipment is maintained. There is a problem called difficult.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is capable of forming a color image having a color balance of a length equal to or longer than the circumference of an image forming body and having a good color balance. The first object is to provide a color image forming apparatus having a relatively compact structure, and the image forming member and the charger and the developing device or the image forming member and the image exposing unit can be easily attached and detached. A second object is to provide a color image forming apparatus capable of easily maintaining the positional accuracy between the equipments, and a third object is to provide an apparatus capable of forming a clear color image having a sufficient toner image density for each color. .

[0004]

The first object is to provide a cleaning device on the outer circumference of a rotating drum-shaped image forming body, and
A different color formed by arranging a pair of a charger and a developing device, and a transfer means, and arranging four image exposure means inside, and repeating charging, image exposure and development on the image forming body. In a color image forming apparatus that transfers and fixes a color image formed by superimposing toner images on a transfer material, one charger is located directly above the image forming body, and two chargers and four chargers are provided. The developing device is symmetrical with respect to a vertical line passing through the center of the image forming body, and there are chargers between the upper and lower developing devices, the lower developing device is near the center level of the image forming body, and the cleaning device is 1 that remains downstream from directly below the forming body
A charger is provided between the cleaning device and the developing device on the downstream side of the cleaning device, and the transfer means is arranged so as to be on the upstream side from directly below the image forming body, and the developing device on the lower side has two agitators. The means are arranged side by side and the upper developing device is
A first invention characterized in that a single agitating means is arranged side by side, or a single charger is provided in the vicinity of directly below the image forming body, and two chargers and four developing devices form an image. A vertical line passing through the center of the formed body is symmetrical, and there are chargers between the upper and lower developing devices, the upper developing device is near the center level of the image forming body, and the cleaning device is directly above the image forming body. The remaining one charger on the further downstream side is provided between the cleaning device and the developing device on the downstream side thereof, and the transfer means is disposed so as to be upstream from the position directly above the image forming body. A second invention is characterized in that the upper developing device has two stirring means arranged side by side, and the lower developing device has two stirring means arranged side by side. The second purpose is to form a pair of an image forming body, four chargers and a developing device, or This is achieved by the first and second embodiments of the invention in which a forming body and four image exposure means are assembled into a cartridge frame and can be integrally attached to and detached from the apparatus main body, and the third object is to achieve four image exposure. This is achieved by the embodiments of the first and second inventions in which the means is arranged so that the image exposure is incident on the position upstream of the developing position of the developing device and corresponding to the position within the front opening range of the developing device.

[0005]

In other words, in the first or second invention, 4
Each developing device is symmetrical with respect to a vertical line passing through the center of the drum-shaped image forming body, and two of them are near the center level of the image forming body.
One developing device is a developing device in which two stirring means are arranged vertically and the height is short, but the horizontal length is short. Two developing devices deviating from the center level are two stirring means horizontal. Since the developing device is low in height in place of being long in the horizontal direction, the device can be made compact.

Further, in the embodiment in which the image forming body and the like are assembled in the cartridge frame and can be integrally attached to and detached from the main body of the apparatus, the attachment and detachment can be easily performed, and, of course, when the components are assembled in the cartridge frame. Position accuracy can be adjusted easily.

Further, four image exposing means are arranged so that the image exposure is incident on the inner peripheral surface of the image forming body at a position corresponding to the upstream side of the developing position of the developing device and within the front opening range of the developing device. In the embodiment, the image exposure transmitted through the image forming body is diffused to disturb the developed electrostatic image, the toner is scattered in the machine during the image exposure, or the formed electrostatic image is developed. It is possible to form a clear color image in which the toner image density of each color is sufficiently high, without being attenuated.

[0008]

The present invention will be described below with reference to the illustrated examples.

FIG. 1 is a schematic sectional view showing an example of a color image forming apparatus of the present invention, FIG. 2 is a partial sectional view of a color image forming apparatus showing an example of a cartridge mounting structure, and FIG. FIG. 4 is a partial sectional view of a color image forming apparatus showing a mounting structure of a cartridge incorporating an image exposing unit together with an image forming body, and FIG. 5 is a schematic sectional view showing another example of the color image forming apparatus of the present invention. 6 and 7
FIG. 3 is a cross-sectional view of a developing device in which agitating means are arranged side by side and a developing device in which agitating means are arranged vertically.

In the drawings, reference numeral 1 is a main body of the apparatus, and 2 is a drum-shaped image forming body having one end face which is rotated clockwise in FIGS. 1 and 5 to 7.

The image forming body 2 shown in FIGS. 2 and 4 is a photosensitive cylindrical body 2a made of a transparent material such as optical glass or transparent acrylic resin having a transparent conductive layer and an organic photosensitive layer (OPC) laminated on the outer periphery thereof. A mirror member 2b having a shaft hole integrally coupled to one end surface side of the photosensitive cylindrical body 2a and having a bearing fitted therein; and the photosensitive cylindrical body 2a.
And an annular gear body 2c integrally formed with the other end surface side of the photosensitive drum body 2a and having a gear formed on the outer periphery protruding from the outer diameter of the photosensitive cylinder body 2a. That is, in the image forming body 2, the annular gear body 2c side is an open end surface for inserting the image exposure means inside the image forming body 2.

The image forming body 2 shown in FIG. 2 has the mirror member 2b at the head and the cartridge frame 3 from the open end face side of the cartridge frame 3.
Then, the shaft pin 3a is fitted into the cartridge frame 3 from the outside of the mirror portion of the cartridge frame 3, and the shaft portion is fitted into the bearing fitted to the mirror member 2b of the image forming body 2. After the flange portion of the cartridge is inserted in a state of pushing the image forming body 2 through the bearing, the front plate 3b is attached to the outside of the mirror portion of the cartridge frame 3 by an appropriate means such as screwing to attach the head of the shaft pin 3a to the front plate.
By fixing the pressed insertion state with 3b, the folded-back portions 3c provided at a plurality of positions on the open end of the cartridge frame 3 are engaged with the inner diameter of the annular gear body 2c, and are supported in the cartridge frame 3. It Folding part of the cartridge frame 3
3c allows the above-mentioned insertion and support of the image forming body 2,
All of the plurality are provided so as to engage with a portion above the half of the image forming body 2 as shown in FIGS.

A guide rail provided with the cartridge frame 3 supporting the image forming body 2 on the apparatus main body 1 as shown in FIG.
When it is engaged with 1a and fed into the apparatus main body 1, the drive gear 1b supported by the apparatus main body 1 becomes an annular gear body as shown in FIG.
The support rollers 1c at a plurality of positions supported by the apparatus main body 1 are engaged with the gears of 2c, and the folded portions 3c of the cartridge frame 3 are provided.
Instead, the image forming body 2 is rotatably supported by engaging with the inner diameter of the annular gear body 2c. This state is fixed by fastening the front plate 3b of the cartridge frame 3 to the apparatus main body 1 with a screw. As a result, the image forming body 2 is mounted and can be rotated clockwise by the drive gear 1b in FIGS. Further, in this mounted state, the transparent conductive layer of the image forming body 2 is grounded.

The image forming body 2 has a charger 4 and a developing device 4 around it.
The outer diameter is preferably 70 mm or more in order to dispose the set, the transfer means and the cleaning device, and the outer diameter is preferably 150 mm or less in order to make the device compact.

A cleaning device 4 removes residual toner on the outer peripheral surface of the image forming body 2 by means of a scraper blade, which is well balanced around the image forming body 2 together with four sets of a charger and a developing device, a transfer device and a separator. Due to the compact arrangement, the operating position of the scraper blade is such that the cleaning device 4 and the transfer device and the separator are separated on the left and right of the vertical line passing through the center of the image forming body 2. In the cleaning device 4 in the example of FIG. 5, it is preferable that both are located on the downstream side, that is, in the range of 5 ° to 45 ° in the clockwise direction, from directly below the image forming body 2. In the transfer device and the separator, the operating position of the transfer device is upstream of the image forming body 2 in the example of FIG. 1, and directly above the image forming body 2 in the example of FIG. Is preferably in the range of 25 to 65 °. If the cleaning device 4 or the transfer device is closer to the position directly below or above the image forming body 2 than the preferable range, the space in contact with the image forming body 2 of the transfer material becomes insufficient. Since the image forming body 2 has to have a large outer diameter in order to dispose the developing device and the developing device, compactness cannot be achieved.

In addition to the scraper blade, the cleaning device 4 of FIG. 1 includes a toner receiving roller that rotates in a counterclockwise direction to receive and send the toner dropped by the scraper blade, and a toner guide blade that drops the toner from the toner receiving roller. It is equipped with a toner feed reciprocating plate that receives the dropped toner on the serrated surface and sends it to the back.
The cleaning device shown in FIG. 5 is provided with an elastic blade roller that rotates counterclockwise and sweeps the toner scraped off by the scraper blade to the inside.

5Y, 5M, 5C and 5K are scorotron chargers that perform corona discharge toward the outer peripheral surface of the image forming body 2, 6Y, 6M, 6C,
6K is a non-contact reversal development method using an electrostatic image formed on the outer peripheral surface of the image forming body 2 charged by the chargers 5Y, 5M, 5C and 5K as described below using a one-component or two-component developer. Yellow (Y), magenta (M), cyan (C),
A developing device for developing a black (K) color toner image.

These chargers 5Y-5K and developing devices 6Y-6K are
One charging device 5C is near the position directly above or below the image forming body 2, two developing devices 6M and 6C are symmetrically arranged on the left and right sides thereof, and two developing devices 6Y and 6K form an image. The two chargers 5M and 5K are symmetrically located in the vicinity of the center level position of the body 2 and are located on the upstream side of the developing devices 6M and 6K, that is, in the counterclockwise direction and at the symmetrical positions of the image forming body 2. The remaining charging device 5Y is disposed so as to be on the upstream side of the developing device 6Y and on the same side of the developing device 6Y and the image forming body 2. Then, with the symmetrical developing device 6M on the upper or lower part of the image forming body 2,
6C is provided with two agitating means 62 in a developer chamber for supplying the developer to the developing roller 61 side by side, and two symmetrical developing devices 6Y near the horizontal center level position of the image forming body 2. When
In 6K, two stirring means 62 are arranged vertically. This secures the installation portion of the charger located between the developing devices, and avoids the developing device from lengthening the process portion in the lateral direction, and the developing devices 6Y to 6Y surrounding the image forming body 2
Since the configuration of 6K and the like is integrated into a substantially square compact including the above-mentioned cleaning device 4, the transfer device and the separator, the entire device can be configured compactly.

FIGS. 6 and 7 show an example of a developing device in which the stirring means 62 are arranged side by side and a developing device in which the stirring means 62 are arranged side by side. In the developing roller 61 of these developing devices, the developing sleeve 61a rotates in the direction of the arrow and the internal magnet body 61b is fixed, and the layer thickness of the developer layer conveyed by the developing roller 61 in the direction of the arrow is a layer thickness regulating rod. It is regulated by 63.

In the developing device of FIG. 6, the developing sleeve
The developer removed from the scraper 61a by the scraper 64 is circulated and stirred by stirring means 62a and 62b composed of screws, on the one hand from the front side to the back side of the paper surface, and on the other hand from the back side to the front side of the paper surface. The toner is supplied from the end of the stirring means 62, and is sufficiently mixed with the developer and stirred by the circulation stirring described above. The developer supply roller 65 is a sponge-like roller that supplies the developer stirred by the stirring means 62 to the developing sleeve 61a.

In the developing device of FIG. 7, the developing sleeve
The developer removed from the scraper 61a by the scraper 64 is a stirring means 62 in which a large number of elliptical plates are inclined and attached to the rotary shaft.
c, stirred by 62d. The toner is dropped and supplied onto the collected developer from the toner supply roller 66 above the scraper 64, and is stirred and mixed by the stirring means 62c. Then, the developer mixed by stirring is dropped, further stirred by the stirring means 62d, and then supplied to the surface of the developing sleeve 61a.

Further, as will be described later, in the examples of FIGS. 6 and 7, the position where the image exposure means inside the image forming body 2 makes the image exposure incident on the inner peripheral surface of the image forming body 2 is the developing device. sleeve
The angle θ is set between the upstream inner edge of the casing opening through which the 61a is viewed and the center of the developing sleeve 61a, preferably θ / 3 from the upstream inner edge. As a result, the size of the image forming apparatus is reduced, leakage of image exposure, and scattering of toner during image exposure are prevented. In order to prevent the image exposure that has entered the developing device from being reflected and re-entering the image forming body 2 or leaking, the inside of the developing device casing, the surface of the developing sleeve 61a, and the like are black and the like. It is preferably placed in a color that absorbs light exposure. Further, when the image forming body 2 and the developing sleeve 61a rotate in the same direction as in FIGS. 6 and 7, the rotation transmission from the annular gear body 2c to the gear of the developing sleeve 61a is as shown in FIGS. Unlike the one shown, there will be a carrier gear between them.

In the example of FIGS. 1 and 5, the cartridge frame 3 is provided with the above-mentioned four sets of chargers 5Y to 5K, developing devices 6Y to 6K, and the cleaning device 4 described above. Therefore, they can be easily assembled, replaced, and maintained, and the positions of the image forming body 2 and the equipment can be easily adjusted. Although the connection to the power source when the chargers 5Y to 5K are attached to the cartridge frame 3 is not shown in FIGS. 2 and 4, the cartridge frame 3 and the apparatus main body 1 are properly provided with sockets and outlets. Be seen.

7Y, 7M, 7C and 7K are FL, EL, PL and LE in which light emitting elements are arranged in an array arranged in the axial direction of the image forming body 2.
D, or an image exposure means composed of a combination of LISA, PLZT, and LCS in which a line-shaped light source and an element having a shutter function are arranged as an example, and a SELFOC lens as an equal-magnification imaging element. Since the respective positions are assigned to and fixed at 8, the respective fixed positions can be easily adjusted. Then, the image exposing means 7Y to 7K are sequentially input with Y, M, C, and K image signals read by an image reading apparatus separate from the color image forming apparatus of the present invention from the memory, so that the charging unit 5Y. , 5M, 5C, 5K charges the inner peripheral surface of the image forming body 2 with image exposure of a dot configuration to form an electrostatic image on the image forming body 2.

In the example of FIG. 2, the cylindrical support 8 to which the image exposing means 7Y to 7K are attached is fixed to the mirror portion of the cartridge frame 3 at the tip end surface which enters the image forming body 2 as described above. The front end side center hole 8a into which the shaft pin 3a is fitted, and the rear end side center hole 8b into which the center pin 1d, which is planted in the apparatus body 1 on the opposite surface, is fitted.
And the rear end side center hole 8b is engaged with the center pin 1d planted in the apparatus body 1, and is fixed to the apparatus body 1 by a tightening screw. Needless to say, it is preferable to engage not only the center pin 1d but also the positioning pin during this fixing.

After fixing the support 8, the cartridge frame 3 is engaged with the guide rail 1a provided in the apparatus body 1 as described above and fed into the apparatus body 1, and the front plate 3b is attached to the apparatus body 1. The support 8 is inserted into the image forming body 2, the shaft pin 3a is fitted into the center hole 8a on the front end side of the support 8, and the image forming body 2 is mounted so that the center is exactly aligned with the support 8. That is, the chargers 5Y to 5K, the developing devices 6Y to 6K, and the image exposure means 7Y.
The relative position of ~ 7K will be set accurately. In addition,
In FIG. 2, 71 is a lead wire for driving the image exposure means 7Y to 7K, and 81 and 82 are a heater and a heat pipe which will be described later.

In the example shown in FIG. 4, the support 8 to which the image exposing means 7Y to 7K are attached is fitted to the bearing mounted on the mirror member 2b of the image forming body 2 at the tip end surface which enters the image forming body 2. Further, a shaft portion 8c whose front end is fitted with a shaft hole provided in the mirror portion of the cartridge frame 3 is formed, and the opposite rear end side is fitted with the cartridge frame 3 so as to tighten a tightening screw or the like. Flange portion 8d coupled to the cartridge frame 3 by the
A plurality of support rollers that are supported by 8d and fit with the inner diameter of the annular gear body 2c of the image forming body 2 to rotatably support the image forming body 2.
8e and a rear end side center hole 8b into which the center pin 1d planted in the apparatus body 1 fits are provided on the opposite surface. In order to rotate the developing sleeve 61a shown in FIGS. 6 and 7 described above,
A carrier gear that meshes with the annular gear body 2c is also provided on the flange portion 8d.

The support 8 is first inserted into the image forming body 2 from the open end side, with the shaft portion 8c at the head, and the shaft portion 8c is a mirror member.
The nut 8f is screwed onto the shaft portion 8c in a state where it is fitted with the bearing mounted on the 2b and the plurality of support rollers 8e are fitted with the inner diameter of the annular gear body 2c, and is coupled with the image forming body 2. The combined body is then inserted into the cartridge frame 3 so that the shaft portion 8c of the support body 8 fits into the shaft hole of the mirror portion of the cartridge frame 3 and the annular gear body 2c of the image forming body 2 or the support body is formed. The carrier frame provided on the flange portion 8d of 8 is engaged with the gear of the developing sleeve 61a to connect the cartridge frame 3 and the support body 8 with a tightening screw.

Finally, the cartridge frame 3 with the front plate 3b
2 is engaged with the guide rail 1a and fed into the apparatus main body 1 as in the cartridge frame 3 of FIG.
The center pin 1d is fitted to the ring gear body 2c meshes with the drive gear 1b, and the lead wires 71 of the image exposing means 7Y to 7K are inserted into the outlet provided in the apparatus main body 1, where the tightening screw is attached. By connecting the front plate 3b to the apparatus main body 1 by means of the above, the image forming means 2 as well as the image exposing means 7Y to 7K and the like are attached to the apparatus main body 1. The color image forming apparatus shown in FIGS. 1 and 5 may be equipped with such a cartridge.

The color image forming process is performed by the above apparatus as follows.

The image information of the original read by the image reading device by the image pickup device or the image information edited by the computer is temporarily stored in the memory as Y, M, C, and K image signals for the respective colors. Next, when image recording is started, the image forming body 2 rotates clockwise in FIGS. 1 and 4, and the cleaning device 4 cleans the outer peripheral surface of the image forming body 2. The charger 5Y discharges the outer peripheral surface of the image forming body 2 to uniformly charge it. The image exposing means 7Y makes image exposure on the charged inner peripheral surface of the image forming body 2 based on the Y image signal input from the memory, and forms a Y electrostatic image on the image forming body 2. The electrostatic image is developed by the developing device 6Y to form a Y toner image on the outer peripheral surface of the image forming body 2.

Then, the charger 5M discharges the outer peripheral surface of the image forming body 2 on which the Y toner image is formed to uniformly charge the Y toner image forming surface of the image forming body 2, and the charged image forming body 2 is charged. Similarly, the image exposing means 7M makes an image exposure based on the image signal of M incident on the inner peripheral surface of the image forming device to form an electrostatic image of M on the image forming body 2, and the electrostatic image is developed by the developing device 6M. A two-color image is formed on the outer peripheral surface of the image forming body 2 by superposition of the M toner image and the previously formed Y toner image.

Next, similarly, a C toner image is similarly formed by the charging device 5C, the image exposing means 7C and the developing device 6C, or further, a K toner image is successively superposed by the charging device 5K, the image exposing means 7K and the developing device 6K. In this way, four color images are formed on the outer peripheral surface of the image forming body 2 within one rotation.

Incidentally, in the above-mentioned color image forming step, each image exposing means for forming an electrostatic image on the image forming body 2.
Since the image exposure by 7Y to 7K is performed on the inner peripheral surface of the image forming body 2 on which the toner image is not formed, the toner image is affected in the same manner from the first to the last electrostatic image. Can be easily formed to form a color image with excellent color balance.
In order to prevent the temperature of 7K or even the image forming body 2 from becoming too high and shortening their life, or the temperature of the image exposing means 7Y to 7K being too low, the ability to decline, A material having good thermal conductivity is used for the support 8, a heater 81 and a heat pipe 82 are embedded, and the heater 81 heats when the temperature is low, and the heat pipe 82 cools when the temperature becomes high. In order to form a well-balanced color image, in the non-contact reversal development by each of the developing devices 6Y to 6K, a developing bias in which direct current or further alternating current is applied to the developing sleeve 61a is applied to the developing sleeve 61a. Is the same as in the color image forming apparatus disclosed in JP-A-5-307307.

However, in the example of FIG. 4, since the heat pipe cannot be used for cooling, the support member 8 is provided with the ventilation hole 8g in the axial direction, and the mirror member 2b of the image forming member 2 is provided with the ventilation hole 2b1. Blower blades 2b2 are provided so that rotation of the image forming body 2 allows air to pass through the ventilation holes 8g of the support 8 for cooling. However, although the heater is not shown in FIG. 4, since it can be connected to the power source in the same manner as the lead wire 71 and the chargers 5Y to 5K,
Available.

In the color image forming apparatus of the present invention shown in FIGS. 1 and 5, further, as shown in FIGS. 6 and 7, image exposure is made incident on the inner peripheral surface of the image forming body 2 by the image exposing means 7Y to 7K. The position to be moved is within the range of the central angle θ formed by both radii drawn from the center of the image forming body 2 to the upstream side edge of the opening seen by the developing sleeve 61a of the developing device 6Y to 6K and the center of the developing sleeve 61a, preferably the image. From the center of the forming body 2 to the developing sleeves of the developing devices 6Y to 6K
The relative positions of the image exposure means 7Y to 7K and the developing devices 6Y to 6K are set so that the angle α formed by both radii drawn between the upstream side edge of the opening which 61a looks into and the incident position of image exposure is θ / 3 or less. It is set. This prevents the image exposure that has passed through the image forming body 2 from diffusing and disturbing the developed electrostatic image, and prevents the toner scattered by the image exposure from leaking out of the developing device and contaminating the inside of the device. A color image excellent in clear color balance can be formed.

In the apparatus shown in FIG. 1, the color image formed on the outer peripheral surface of the image forming body 2 is fed from the lower paper feed stacker 9 through the friction feed roller 10 and the pressure conveying roller 11 or by the manual feed guide 12. The transfer device 14 transfers the transfer paper from the side to the transfer paper fed by the timing roller 13 through the clamping pressure conveying roller 11, and in the apparatus shown in FIG.
It is transferred by the transfer device 14 to the transfer paper fed by the timing roller 13 via the. In any of the devices, the transfer paper on which the color image is transferred is separated by the separator.
It is separated from the image forming body 2 by 16 and suction means 17
The color image is conveyed by the suction conveyor 17 provided with a, the color image is fixed by the heat roller fixing device 18, and then discharged outside the apparatus. On the other hand, the outer peripheral surface of the image forming body 2 from which the transfer paper has been separated is cleaned of the residual toner by the cleaning device 4 and is provided for the next color image forming step.

[0038]

As described above, in the color image forming apparatus of the present invention, the four developing devices are symmetrical with respect to the vertical line passing through the center of the drum-shaped image forming body, of which the vicinity of the center level of the image forming body. The two developing devices are two developing devices arranged vertically and the height is high, but the horizontal length is short. The two developing devices deviating from the center level have two stirring means. Since the developing device has a low height instead of a long horizontal direction, the device can be made compact.

Further, the image forming body, four pairs of chargers and developing device pairs, or the image forming body and four image exposing means can be integrally attached to and detached from the apparatus main body as a cartridge,
It is possible to easily assemble, replace, and maintain them, and adjust the positional accuracy between these equipments.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a color image forming apparatus of the present invention.

FIG. 2 is a partial cross-sectional view of a color image forming apparatus showing an example of a cartridge mounting structure.

FIG. 3 is a perspective view showing how the cartridge is attached and detached.

FIG. 4 is a partial cross-sectional view of a color image forming apparatus showing a mounting structure of a cartridge that incorporates an image exposing unit together with an image forming body.

FIG. 5 is a schematic structural sectional view showing another example of the color image forming apparatus of the present invention.

FIG. 6 is a schematic cross-sectional view of a developing device in which stirring means are arranged side by side.

FIG. 7 is a schematic sectional view of a developing device in which agitating means are arranged vertically.

[Explanation of symbols]

 1 Device body 2 Image forming body 3 Cartridge frame 4 Cleaning device 5Y, 5M, 5C, 5K Charging device 6Y, 6M, 6C, 6K Developing device 7Y, 7M, 7C, 7K Image exposure means 8 Support 9 Feed stacker 10 Friction Feeding roller 11 Nip pressure conveying roller 12 Manual feed guide 13 Timing roller 14 Transfer device 15 Paper feed cassette 16 Separator 17 Adsorption conveyor 18 Heat roller fixing device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 21/18 15/08 506 A 21/10 G03G 15/00 556 21/00 318 354

Claims (13)

[Claims] 1. A cleaning device, a pair of four chargers and a developing device, and a transfer means are provided on the outer periphery of a rotating drum-shaped image forming body, and four image exposing means are provided inside. do it,
In a color image forming apparatus for transferring and fixing a color image formed by superposing different color toner images formed by repeating charging, image exposure and development on an image forming body, one charger is used to form an image. Near the top of the body, 2
The four chargers and the four developing devices are symmetrical with respect to a vertical line passing through the center of the image forming body, and there are chargers between the upper and lower developing devices, and the lower developing device is the center level of the image forming body. In the vicinity, the cleaning device is located on the downstream side from directly below the image forming body, the remaining one charger is located between the cleaning device and the developing device on the downstream side, and the transfer means is located directly below the image forming body. The developing device on the lower side has two stirring means arranged side by side in the vertical direction.
A color image forming apparatus, wherein the upper developing device has two stirring means arranged side by side. 2. The color image forming apparatus according to claim 1, wherein the image forming body has an outer diameter of 70 to 150 mm. 3. The color image forming apparatus according to claim 1, wherein the cleaning device brings the operating portion into contact with a peripheral surface in a range of 5 to 45 ° downstream from directly below the image forming body. 4. The color image forming apparatus according to claim 1, wherein the transfer means opposes the operating portion to the peripheral surface in the range of 25 to 65 ° upstream from right below the image forming body. 5. The color image forming apparatus according to claim 1, wherein four sets of the image forming body, the charger, and the developing device, and a cleaning device are attached to a cartridge frame and can be integrally attached to and detached from the apparatus main body. 6. The color image forming apparatus according to claim 1, wherein the image forming body and the four image exposing units are assembled in a cartridge frame and can be integrally attached to and detached from the apparatus main body. 7. A cleaning device, a pair of four chargers and a developing device, and a transfer means are provided on the outer periphery of a rotating drum-shaped image forming body, and four image exposing means are provided inside. do it,
In a color image forming apparatus for transferring and fixing a color image formed by superposing different color toner images formed by repeating charging, image exposure and development on an image forming body, one charger is used to form an image. Near the bottom of the body, 2
The four chargers and four developing devices are symmetrical with respect to a vertical line passing through the center of the image forming body, and there are chargers between the upper and lower developing devices, and the upper developing device is near the center level of the image forming body. The cleaning device is on the downstream side of the image forming body, the remaining one charger is between the cleaning device and the developing device on the downstream side, and the transfer unit is directly on the image forming body. It is arranged so as to be on the more upstream side, and the upper developing device has two stirring means arranged side by side vertically,
A color image forming apparatus, wherein the lower developing device has two stirring means arranged side by side. 8. The color image forming apparatus according to claim 7, wherein the image forming body has an outer diameter of 70 to 150 mm. 9. The color image forming apparatus according to claim 7, wherein the cleaning device is provided within a range of 5 to 45 ° on the downstream side of the image forming body. 10. The transfer means is arranged within a range of 25 to 65 ° upstream from the position right above the image forming body.
The color image forming apparatus described in 1. 11. The color image forming apparatus according to claim 7, wherein the image forming body, the four sets of the charging device and the developing device, and the cleaning device are attached to a cartridge frame and can be integrally attached to and detached from the apparatus main body. . 12. The color image forming apparatus according to claim 1, wherein the image forming body and the four image exposing units are assembled in a cartridge frame and can be integrally attached to and detached from the apparatus main body. 13. The image exposure device according to claim 1, wherein the four image exposure means are arranged so as to make image exposure incident on a position corresponding to an inside of a front opening range of the developing device on the upstream side of the developing position of the developing device. The color image forming apparatus according to claim 7.