JPH0743972A - Color electrophotographic device and image forming unit - Google Patents

Abstract

PURPOSE:To provide a color electrophotographic device simple in constitution capable of obtaining a beautiful color image and excellent in maintainability and to produce an image forming unit used therefor. CONSTITUTION:The plural image forming units consisting of an electrostatic charged image carrier, a developing means provided with different-color toner and the cleaning means of the electrostatic charge image carrier are used. All of image forming unit groups 1BK, 1Y, 1B and 1C are rotated and moved so that they can be successively moved to the same image forming position. At the image forming position, the image is exposed and formed by signal light made incident from the outside of the unit groups 1BK, 1Y, 1B and 1C by the image forming unit. Then, the toner image thereof is transferred onto a faced intermediate transfer belt. The image forming unit can be independently drawn out to the outside of the device at a different position from the image forming position. The electrostatic charged image carrier of the image forming unit is protected by a cover at a position other than the image forming position. The image forming unit at the image forming position is successively replaced and the toner images of the respective colors are superposed and transferred on the intermediate transfer belt by aligning the positions thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color electrophotographic apparatus applicable to a color printer, a color copying machine, a color fax machine and the like, and an image forming unit used for the same.

[0002]

2. Description of the Related Art Generally, in order to form a color image by electrophotography, a method of forming a color image by superposing toner images of yellow, magenta, cyan and black on a transfer material is used. As a method of forming this color image, toner images of respective colors are sequentially formed on one photoconductor, the transfer material wound around a transfer drum is rotated to repeatedly face the photoconductor, and each of the colors of the colors sequentially formed there is formed. A transfer drum method in which toner images are transferred in an overlapping manner, and a plurality of image forming units are arranged side by side, and a toner image of each color is sequentially transferred to a transfer material conveyed by a belt or the like through each image forming unit position. In general, the continuous stacking method is used.

An example of a color image forming apparatus using the former transfer drum system is disclosed in Japanese Patent Laid-Open No. 1-252982.

FIG. 5 shows an outline of the overall configuration of this conventional example, and the configuration and operation will be briefly described below. In FIG. 5, reference numeral 101 denotes a photoconductor, which is opposed to the photoconductor and is the charger 1.
02, a developing unit 103, a transfer drum 104, and a cleaner 105 are provided. The developing unit 103 includes a Y developing device 106 for forming a yellow toner image, an M developing device 107 for magenta color, and a C developing device 10 for cyan color.
8, and a K developing device 109 for black color, which is rotated as a whole so that each developing device sequentially faces the photoconductor 101 to be in a developable state.

During operation, the transfer drum 112 and the photoconductor are opposed to each other and rotate at a constant speed in the directions of the arrows.

First, when the operation starts, the photosensitive member 101 rotates in the direction of the arrow, and the surface of the photosensitive member 101 is uniformly charged by the charger 102.

Thereafter, on the surface of the photosensitive member, a laser beam 110 modulated with a signal for forming a first color yellow image is formed.
And a latent image is formed. Further, this latent image is first developed by the yellow developing device 106 facing the photoconductor to form a yellow toner image. By the time the formed yellow toner image reaches the position facing the transfer drum 104, one sheet of paper as a transfer material already sent from the paper feeding unit 111 is already on the outer periphery of the transfer drum 104 with the leading end claw portion. The toner image is formed by being gripped by 112 and wound, and the toner image is formed at a predetermined timing so that the yellow toner image on the photoconductor faces and meets the predetermined position.

After the yellow toner image on the photoconductor is transferred to the paper by the action of the transfer charger 113, the surface of the photoconductor is cleaned by the cleaner 105 to prepare for the formation of the next color image. Subsequently, magenta, cyan, and black toner images are also formed in the same manner, but at that time, the developing unit 103 makes each developing device, which is used according to the color, face the photoconductor to be in a developable state. The diameter of the transfer drum is large enough so that the longest sheet of paper can be wound and the developing unit can be exchanged between images of each color.

Laser beam 110 for image formation of each color
The irradiation is performed with a timing such that the toner images of the respective colors on the photoconductor and the toner images already transferred to the paper on the transfer drum are aligned and face each other as the toner rotates. In this way, the four color toner images are transferred to the transfer drum 10.
4 is transferred onto the paper in a superimposed manner to form a color image on the paper. After the toner images of all colors have been transferred, the paper is peeled from the transfer drum 104 by the peeling claw 114, and the upper toner image is fixed by the fixing unit 116 via the conveyance unit 115 and is discharged to the outside of the apparatus. The above is a brief description of the configuration and operation of the conventional example.

On the other hand, as an example of a color image forming apparatus using a continuous transfer system, there is JP-A-1-250970. In this example, four image forming stations each including a photoconductor, an optical scanning unit, and the like are arranged to form an image of four colors, and a sheet conveyed on a belt passes under the respective photoconductors. The toner images are overlaid.

Further, as another method for forming a color image by superposing toner images of different colors on a transfer material, the toner images of respective colors sequentially formed on the photoconductor are once superposed on the intermediate transfer material, Finally, a method of collectively transferring all of the above to a transfer material is disclosed in JP-A-2-183276.

[0012]

Among the conventional examples as described above, in the transfer drum system, the transfer drum is used in order to superimpose the positions of the toner images of different colors. By rotating this transfer drum at the same speed with respect to the photoconductor and adjusting the timing of the leading edge of the image, the mutual positions of the toner images of the respective colors when forming a color image are matched. However, in the above-mentioned configuration, since it is necessary to wind the paper around the transfer drum, the diameter of the transfer drum needs to be a certain size or more, and the structure is very complicated, so that the device is large. Was becoming.

Further, strong paper such as postcards and cardboard cannot be used because it cannot be wound around the transfer drum.

Furthermore, maintenance such as replacement of the photosensitive member requires a very complicated work, and requires a skilled expert.

On the other hand, the continuous transfer system has an image forming position corresponding to the number of colors, and a transfer drum is not required because it is sufficient to pass the paper one by one therethrough. A latent image forming means such as a laser optical system for forming a latent image is required corresponding to the number of colors, and the structure is very complicated and expensive in this portion. Furthermore, since there are a plurality of image forming positions, the relative positional relationship of the image forming portions of each color greatly affects the color misregistration. In particular, it is necessary to perform accurate alignment between the colors of the latent image by the latent image forming means, and as shown in the example of JP-A-1-250970, the latent image forming means of the image exposure system There was a problem that considerable devise and complicated structure were required.

In addition, due to the complexity of these alignments, when parts such as the photoconductor are replaced during maintenance, accurate reproducibility of this alignment is very difficult, which complicates maintenance.

Further, Japanese Patent Laid-Open No. 2-1 uses an intermediate transfer material.
In the example disclosed in Japanese Laid-Open Patent Publication No. 83276, the size of the photosensitive member is increased so that a toner image of each color can be formed on one photosensitive member by each color developing unit. For example, a belt-shaped photosensitive member is required. It becomes. In addition, there is a problem that it is difficult to maintain the developing device for each color and the photoconductor. For example, each developing device needs image adjustment and position adjustment with the photoconductor at the time of maintenance, or the same when replacing the photoconductor.

In view of the above problems, the object of the present invention is to perform color registration with a compact and simple structure that does not require a complicated transfer drum and does not require a complicated structure for aligning the image exposure system. To provide an excellent color electrophotographic apparatus which can be accurately performed, has a simple structure of a toner image forming unit including a photoconductor and a developing unit, and has good maintainability, and an image forming unit used for the same. .

[0019]

In order to achieve the above-mentioned object, the present invention comprises an electrostatic image carrier that rotates at least, and developing means having toners of different colors. A plurality of movable image forming units capable of forming toner images of different colors on the electric image carrier, and transfer for transferring the toner image on the electrostatic image carrier to the transfer body at a single transfer position. Means, an exposure means for performing image exposure at a single exposure position corresponding to the transfer position, and an image forming unit corresponding to the exposure position and corresponding to the transfer position. Moving means for moving the entire group of image forming units so as to sequentially position the image forming units, an openable and closable cover attached to each of the image forming units for protecting the electrostatic image carrier, and at least the image forming unit for the covers. A color electronic device that has a cover opening / closing unit that operates according to the movement of the image forming unit so as to open at a position, and transfers toner images of different colors onto a transfer body in a superimposed manner to form a color image. It is a photographic device.

Further, the present invention is provided with a developing means each having at least a rotating electrostatic image carrier and a toner having a different color, and a cleaning means for cleaning the toner on the electrostatic image carrier. A plurality of movable image forming units capable of forming toner images of different colors on the electrostatic image carrier, and the toner image on the electrostatic image carrier is transferred to the transfer body at a single transfer position. A transfer unit for performing image exposure at a single exposure position corresponding to the transfer position, and a plurality of image forming units respectively corresponding to the exposure position and the transfer position. Moving means for moving the entire image forming unit group so as to sequentially position at the image forming position, an openable / closable cover attached to each of the image forming units to protect the electrostatic image carrier, and the image forming Uni Of a different color on the transfer body, having a structure in which the cover is removable from the apparatus at a position other than the image forming position, and a cover opening / closing unit that acts to close the cover at least at the removable position of the image forming unit. Is a color electrophotographic apparatus that forms a color image by transferring the toner images of (1) and (2) in a superimposed manner. Further, according to the present invention, each has at least a rotating electrostatic image carrier and a developing unit having a toner of a different color, so that toner images of different colors can be formed on the electrostatic image carrier. A plurality of movable image forming units, a transfer means for transferring the toner image on the electrostatic image carrier onto a transfer material at a single transfer position, and a single exposure position associated with the transfer position. The image forming unit group is rotationally moved in order to sequentially position each of the exposure unit for performing image exposure and the plurality of image forming units at the image forming position corresponding to the exposure position and corresponding to the transfer position. A moving means, and an openable / closable cover attached to each of the image forming units to protect the electrostatic image carrier, and the cover forms an image forming unit at least when passing through the transfer position. A color image is formed by transferring toner images of different colors on the transfer body in superposition with each other, which is located inside and inside the arc drawn by the outermost peripheral portion of the electrostatic image carrier when the group is rotationally moved. A color electrophotographic apparatus for performing the above and an image forming unit used for the same.

[0021]

With the above construction, since a transfer drum having a complicated construction is not used, it is simple, and since image formation of each color including exposure and transfer is carried out at the same image forming position, the construction is simple and accurate. You can align different colors. Further, since the developing means and the photoconductor can be configured as a set for each color, the maintenance property such that only the previously adjusted image forming unit can be exchanged from the outside becomes excellent.

Further, the image forming unit can be easily replaced by the user without polluting or damaging the photoconductor because the photoconductor is protected by the cover at the time of replacement.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color electrophotographic apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention. First, black, yellow in the center,
Four sets of fan-shaped image forming units 1Bk, 1Y, 1M, and 1C for each color of magenta and cyan constitute an image forming unit group, and are arranged in an annular shape as shown in the drawing. Since each image forming unit is made of the same constituent member except for the developer contained therein, the image forming unit for black will be described and the other colors will be omitted for simplification of description. Note that, for each color, the same portions are denoted by the same reference numerals, and when it is necessary to distinguish each color, the reference numerals are attached to indicate the respective colors. FIG. 2 shows the black image forming unit 1B.
k is shown in detail.

In FIG. 2, 9 is an organic photoreceptor in which phthalocyanine is dispersed in a polycarbonate binder resin, 1
0 is a non-rotating magnet fixed coaxially with the photoconductor 9;
Is a charging roller for negatively charging the photoconductor, 13 is signal light by a laser beam, and 14 is a developer hopper.

In the developer hopper 14, a two-component developer 26 is prepared by mixing a toner carrier 25Bk with a ferrite carrier 24Bk having a particle size of 50 μm, the surface of which is coated with a silicone resin.
Bk was added and magnetically attached to the surface of the photoconductor 9. The toner used is a polyester resin in which a pigment or the like is dispersed and an additive is further added.

Reference numeral 17 is a rotatable collection electrode roller made of aluminum, 16 is a non-rotating magnet fixed coaxially therein, 18 is an AC high voltage power source for applying a voltage to the collection electrode roller, and 19 is on the collection electrode roller. It is a scraper made of polyester film that scrapes off toner. Photoconductor 9
Has a diameter of 30 mm and is rotated in the direction of the arrow at a peripheral speed of 60 mm / s. The recovery electrode roller 17 has a diameter of 16 mm and a peripheral speed of 60 mm.
It was rotated in the direction of the arrow with / s.

Reference numeral 27 is a cleaner for cleaning the toner remaining on the surface of the photoconductor after transfer. The operation of the image forming unit configured as described above will be described below with reference to FIG. The photoreceptor 9 was charged to −500V by the charging roller 11. Signal light 1 by the laser beam is applied to the photoconductor 9.
3 was irradiated to form an electrostatic latent image. At this time, the exposure potential of the photoconductor was -100V.

A two-component developer 26 is formed on the surface of the photoreceptor 9.
M was attached in the developer hopper 14 by magnetic force. Next, the surface of the photoconductor 9 was passed in front of the recovery electrode roller 17. When the photoconductor 9 passes through the uncharged area, the electrode roller 17
The AC high-voltage power supply 18 applied an AC voltage (frequency: 1 kHz) of 750 V 0-p (peak-to-peak 1.5 kV) on which a DC voltage of 0 V was superimposed. After that, -5
When passing through the surface of the photoreceptor 9 charged with 00V and having an electrostatic latent image written therein, 750V 0-p (peak-to-peak 1. An alternating voltage (frequency: 1.5 kHz) of 5 kV) was applied. Then, the toner attached to the carrier and the charged portion on the photoconductor 9 was collected by the electrode roller 17, and the negative-positive inverted toner image remained only on the image portion on the photoconductor 9. Electrode roller 17 rotating in the direction of the arrow
The carrier and toner adhering to was scraped off by the scraper 19 and returned to the developer hopper 14 again to be used for the next image formation.

In this way, a black toner image is obtained on the photosensitive member 9. The image forming unit in FIG. 2 is a black image forming unit, and also shows the upper and lower positions of the image forming unit at the image forming position. In the figure, the developer 26Bk
The developer hopper 14 in which the
Is located on the lower side, it is possible to smoothly perform development and cleaning without providing a feeding mechanism or a stirring mechanism for moving the developer or toner inside the developer hopper or inside the cleaner. That is, in the developer hopper, the developer is supplied onto the photoconductor 9 by its own weight, and in the cleaner, the toner scraped off by the blade falls to the bottom of the cleaner by its own weight and separates from the photoconductor.

Further, 28 is a photoconductor cover for protecting the photoconductor 9, which is shown in an opened state in FIG. 2 for image formation. The structure and operation of the opening / closing means for the photoconductor cover 28 will be described later.

The developing devices 1Y, 1M, and 1C other than black have the same structure and operate.

The configuration of the printer section will be described again with reference to FIG. Image forming unit 1B arranged in an annular shape
k, 1Y, 1M, and 1C are supported by a support (not shown), and are driven by a moving motor 30 controlled by a control circuit 29, which is a moving means, and are fixed in a cylindrical shape and do not rotate. It is rotatable around the shaft 31 in the arrow direction. Each image forming unit is sequentially moved to and positioned at an image forming position 50 facing a transfer roller 33 that supports an intermediate transfer belt 32 described later. Image formation position 5
0 is also the exposure position by the signal light 13.

Reference numeral 3 denotes a laser exposure device, which is a signal light 13 by a laser beam modulated by a signal input to the printer section.
Of the image forming units 1Bk and 1Bk of FIG.
After passing through the optical path formed between the Y-shaped sectors, the light enters the mirror 5 fixed inside the shaft 31 through the transparent window 4 formed in a part of the shaft 31, and is reflected to the image forming position 50. The photoconductor 9 of an image forming unit is irradiated with the latent image to form a latent image.
In the state of FIG. 1, it acts on the black image forming unit 1Bk.

Here, since the optical path to the mirror 5 is along the wall surfaces of the fan-shaped image forming units on both sides, there is almost no portion wasted as an occupied area of the image forming unit group. Further, since the mirror 5 is provided in the central portion of the image forming unit group, it can be configured by only one fixed mirror, which is simple and highly reliable for alignment and the like. The reflecting surface of the mirror 5 is
Since the optical path is set so as to face downward, dust and the like inside the machine are less likely to collect on the reflecting surface.

Reference numeral 32 is an intermediate transfer belt having a thickness of 100 μm.
Endless belt-like semi-conductive urethane film as a base material, wound around a transfer roller 33 and a stainless steel roller 34 formed of urethane foam with low resistance treatment, and movable in the arrow direction. Has become. Here, in this embodiment, the drive roller 34 and the roller 35
The distance between them is set so that the perimeter is slightly longer than the length of the A4 sheet in the longitudinal direction. The transfer roller 33 is lightly pressed against the photoconductor 9 of the unit 1Bk at the image forming position via the intermediate transfer belt 32. A second transfer roller 35, which has the same structure as the transfer roller 33, is pressed against the roller 34 via the intermediate transfer belt 32 so as to be driven and rotated.

Intermediate transfer belt 32 and second transfer roller 35
The paper feed portions 36a and 36b
A paper transport path is formed so that the paper is fed from the.

A belt cleaner 40 includes a belt cleaner for cleaning the intermediate transfer belt.

Reference numeral 44 is a fixing device for fixing the toner image on the paper after transfer, and 45 is a discharging roller for discharging the paper after fixing.

The above is the description of the main structures of the electrophotographic apparatus and the image forming unit of the present invention. Next, the operation of this apparatus when forming a color image will be described.

First, each image forming unit is in the position as shown in FIG. 1, and the image forming unit 1Bk for black is used.
Are positioned at the image forming position 50. It also faces the transfer roller 33. Black signal light is input to the image forming unit 1Bk by the laser exposure device 3, the operation of the image forming unit is started, and an image is formed with black toner. At this time, the image forming speed of the image forming unit 1Bk (equal to the peripheral speed of the photosensitive member) and the moving speed of the intermediate transfer belt are set to be the same, and at the same time when the image is formed, the transfer roller 33 acts at the same time. , The black toner image is transferred to the intermediate transfer belt. Immediately after all the black toner images have been transferred, the image forming unit groups 1Bk, 1
The Ys, 1Ms, and 1Cs are wholly driven by the movement motor 30 to integrally rotate and move in the direction of the arrow in FIG. 1 and rotate exactly 90 degrees to stop at the position where the image forming unit 1Y reaches the image forming position 50. The image forming unit 1Y is positioned. During this movement, the portion of the toner hopper 14 (see FIG. 2) other than the photoconductor of the image forming unit is located inside the rotational arc of the tip of the photoconductor, so that the intermediate transfer belt contacts the image forming unit. There is no such thing.

After the image forming unit 1C arrives at the image forming position 50, the laser exposure device inputs the signal light to the image forming unit 1Y by the yellow signal as before, and the yellow toner image is formed and transferred. Be seen. At this time, the intermediate transfer belt makes one rotation, and the writing timing of the yellow signal light is controlled so that the toner image of the next yellow image is positionally aligned with the previously transferred black toner image. During this time, the second
The transfer roller 35 and the cleaner section 40 are slightly separated from the intermediate transfer belt so that the toner image thereon is not affected.

The same operation as described above is performed for magenta and cyan, and four color toner images are positionally aligned and superposed on each other on the intermediate transfer belt to form a color image. After the final transfer of the cyan toner image, the four color toner images are collectively transferred by the action of the second transfer roller 35 onto the paper fed from the paper feed unit 36a or 36b at the same timing. The toner image transferred onto the paper is fixed by the fixing device 44. The sheet is then discharged to the outside of the apparatus via the discharge roller 45. The transfer residual toner remaining on the intermediate transfer belt is cleaned by the action of the cleaner unit 40 to prepare for the next image formation.

Next, the operation in the monochromatic mode will be described. In the monochromatic mode, first, the image forming unit of a predetermined color is moved to the image forming position and positioned. Next, the same color image formation and transfer to the intermediate transfer belt are performed in the same manner as before, and this time after transfer, the transfer is continued as it is, and the transfer is performed on the paper sent from the paper supply unit by the next second transfer roller. I will do it.

Next, the structure and operation for opening and closing the photoconductor cover 28 attached to the image forming unit will be described with reference to FIG.
Will be explained. FIG. 3 is a diagram showing a photoconductor cover opening / closing mechanism provided at an end portion in the central axis direction of the rotational movement of the image forming unit group.

As shown in the drawing, the photoconductor cover 28 attached to each image forming unit has levers 47 and 48 rotatably provided on the side surface of each image forming unit.
Both ends are pivotally supported. Therefore, when the opening / closing movement is shown by the cyan image forming unit 1C, the photosensitive member cover 28C normally urges the spring 49C to cover the photosensitive member at the position indicated by the solid line, as shown in the figure. On the other hand, lever 47C
When is rotated to the left, the photoconductor cover 28C enters the recess 51C provided on the outer peripheral surface of the image forming unit 1C by tracing the locus of an arc indicated by a chain line at both ends.
It fits in the position shown in.

The photoconductor cover can be opened and closed as described above. Next, the relationship with the rotational movement of the image forming unit group will be described.

As shown by the image forming units in FIG. 3 having the same positional relationship as in FIG. 1, the photoconductor covers 28Y, 2 of the yellow, magenta and cyan image forming units which are not in the image forming position.
8M and 28C are in the closed position. On the other hand, the photoconductor cover 28 of the black image forming unit 1Bk at the image forming position
Bk is in the open position as shown in the drawing, because the tip of the lever 47Bk is pushed by the cam 52 fixed to the shaft 52.

Since the cam 52 is fixed to the shaft 31 that does not rotate, the entire image forming unit group rotates in the direction of the arrow to move the units at the image forming position in tandem.
The cover of the unit approaching the image forming position is opened in front of it, and the cover of the unit moving away from the image forming position is closed.

At this time, when the cover of the unit approaching the image forming position passes through the position facing the first transfer roller 33, the cover is already in the open state, and the cam 52 is placed in the recess 51. The shape of is set.

Therefore, since the photoconductor cover 28 is inside the arc (indicated by 53 in FIG. 3) of the tip of the photoconductor 9 when the image forming unit group is rotationally moved, the photoconductor cover 28 contacts the intermediate transfer belt 32 or the like. You can pass without doing.

The above is the description of the photoconductor cover. Next, maintenance of this device will be described with reference to FIG.

It is assumed that the developer of a specific color is consumed and runs out, and maintenance is performed. First, by the action of the moving motor 30 controlled by the control circuit 29 according to a command from an operator (by a switch not shown),
The image forming unit group is rotated to move the image forming unit of the color of interest to the upper position (the position of the image forming unit 1C in FIG. 1). Then, as shown in FIG. 4, the operator opens the cover 46 located on the upper part of the apparatus main body, and takes out only the image forming unit of interest from the apparatus out of the apparatus. Next, a new image forming unit of that color that has been adjusted in advance as an image forming unit is mounted.

Therefore, after mounting, image formation can be started without any adjustment. At this time, since the photoconductor cover is in the closed state as described above, the operator does not touch the photoconductor.

Further, since the image forming unit to be replaced can be replaced at an upper position different from the image forming position, the image forming unit is not disturbed by the related members such as the transfer portion and is not positioned, so that the image forming unit can be easily replaced outside the apparatus. It is possible to take it out and it is excellent in maintainability.

The above is the description of the configuration and operation of the embodiment.
According to the present invention, since the image formation of each color is performed at the same image forming position without using a transfer drum having a complicated configuration, the present invention can perform accurate color registration with a simple configuration, and The image forming unit is completed independently as one image forming unit for each color, so that the structure is simple, and the maintainability such that the image forming unit can be easily replaced for each color is excellent.

Further, in this configuration, since each image forming unit including the photoconductor can be independently adjusted externally, it is possible to easily replace a unit which has already been adjusted at the time of factory shipment without any adjustment on site. .

Since the photoreceptor is covered except when the image is formed, the photoreceptor is not damaged or soiled, and the interior of the apparatus is not soiled by the scattering of the developer.

Further, in this structure, even when a color image is continuously formed, each photoconductor is paused while forming another color, so that a stable image is obtained without electrostatic fatigue. can get.

In the above embodiments, a specific developing method was used for the image forming unit. However, even in the case of an image forming unit having a structure using another developing method, the essence and the effect of the present invention are It never changes.

[0061]

As described above, the present invention has a simple structure because a transfer drum having a complicated structure is not used, and since image formation for each color is performed at the same image forming position,
Accurate color registration can be performed with a simple structure. And since the image forming unit is completed as one image forming unit independently for each color, the configuration is simple,
Further, the maintainability such as the image forming unit adjusted in advance for each color can be easily replaced becomes excellent.

Further, the image forming unit does not damage or stain the photoconductor because the photoconductor is covered during replacement.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an image forming unit used in a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a configuration and an operation of opening and closing a cover of a photoconductor.

FIG. 4 is an explanatory diagram when replacing an image forming unit.

FIG. 5 is a block diagram of a conventional color electrophotographic apparatus.

[Explanation of symbols]

 1Bk, 1C, 1M, 1Y Image forming unit 3 Laser exposure device 5 Mirror 9 Photoconductor 13 Signal light 28 Photoconductor cover 32 Intermediate transfer belt 33 Transfer roller 35 Second transfer roller 50 Image forming position

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 21/18

Claims (4)

[Claims] 1. Each comprises at least a rotating electrostatic image carrier and a developing means having a toner of a different color, so that toner images of different colors can be formed on the electrostatic image carrier. A plurality of movable image forming units, a transfer means for transferring the toner image on the electrostatic image carrier to the transfer body at a single transfer position, and a single exposure position corresponding to the transfer position. A moving unit for moving the entire image forming unit group so as to sequentially position each of the exposure unit for performing image exposure with the image forming unit and the plurality of image forming units at an image forming position corresponding to the exposure position and corresponding to the transfer position. Means, an openable and closable cover attached to each of the image forming units to protect the electrostatic image bearing member, and with the movement of the image forming units so as to open the cover at least at the image forming position. A cover opening means for moving, the different color toner images on the transfer member, transferred to overlap the position, color electrophotographic apparatus which performs color image formation. 2. An electrostatic image carrier, each of which has at least a rotating electrostatic image carrier, and a developing device having a toner having a different color from each other, and a cleaning device for cleaning the toner on the electrostatic image carrier. A plurality of movable image forming units capable of forming toner images of different colors on the image carrier,
Transfer means for transferring the toner image on the electrostatic image bearing member to a transfer body at a single transfer position; exposure means for performing image exposure at a single exposure position corresponding to the transfer position; Moving means for moving the entire image forming unit group so as to sequentially position each of the image forming units at the image forming position corresponding to the exposure position and corresponding to the transfer position, and attached to each of the image forming units. And a cover that can be opened and closed to protect the electrostatic image bearing member, and a configuration in which the image forming unit can be inserted and removed from the apparatus at a position other than the image forming position, and the cover can be at least a position where the image forming unit can be inserted and removed. A color electrophotographic apparatus having a cover opening / closing unit that operates so as to be closed by the above, and forms a color image by transferring toner images of different colors on a transfer body at overlapping positions. 3. Each comprises at least a rotating electrostatic image carrier and a developing means having a toner of a different color, so that toner images of different colors can be formed on the electrostatic image carrier. A plurality of movable image forming units, a transfer means for transferring the toner image on the electrostatic image carrier onto a transfer material at a single transfer position, and a single exposure position associated with the transfer position. The image forming unit group is rotationally moved in order to sequentially position each of the exposure unit for performing image exposure and the plurality of image forming units at the image forming position corresponding to the exposure position and corresponding to the transfer position. A cover that can be opened and closed to protect the electrostatic image carrier attached to each of the image forming units, and the cover forms an image at least when the transfer position is passed. unit From arc outermost peripheral portion drawn during the rotational movement of the electrostatic image bearing member, a structure located in the inner back,
A color electrophotographic apparatus that forms a color image by transferring toner images of different colors on a transfer body at overlapping positions. 4. An image forming unit which can be detachably attached to an apparatus main body and which is rotationally moved in the attached state, and protects at least an electrostatic image carrier, a developing means and the electrostatic image carrier. An openable and closable cover, and the cover is a structure that can be positioned inside the arc from a circular arc drawn by the locus of the outermost peripheral portion of the electrostatic image bearing member during rotational movement in the device. An image forming unit used in a color electrophotographic apparatus.