JPH05216325A - Color electrophotographic copying device - Google Patents

Abstract

PURPOSE:To provide a device which is miniaturized, whose constitution is simple, by which a beautiful color image can be obtained and whose maintainability is excellent by providing a mode that the moving speed of a transfer belt is actuated at a speed which is different from the speed during an image forming time, at a fixing time after a required toner image is transferred. CONSTITUTION:Four sets of image forming units 1BK, 1C, 1M and 1Y of black, cyan, magenta and yellow are arranged in a printer part by being arrayed. The transfer belt 31 is wound round a driving roller 34 and a roller 35 so that it can be reciprocatingly moved while it attracts a paper on the surface thereof. Then, the image is successively formed and transferred by the units of the respective colors 1BK, 1C, 1M and 1Y and superposed while the transfer paper on the belt 31 is reciprocatingly moved. Since the leading edge of the paper does not arrive at a fixing device just after the transfer of the last toner image is finished, an action mode is changed at this time and the moving speed in, the forward direction of the belt 31 and the speed of the fixing device are lowered. As the result, low-speed fixation is realized and the production of an OHP or the like is realized.

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 printers, facsimiles and the like.

[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 is used. As a general method of superposing the toner images on the transfer material, there is an example of a color image forming apparatus 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 rotate in opposition to each other at a constant speed while facing each other.

First, when the operation starts, the photosensitive member 101 rotates in the direction of the arrow, and the surface thereof 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 sent from the paper feed unit 111 has already been grasped by the pawl portion 112 on the outer periphery of the transfer drum 104. The toner image is formed so that the yellow toner image on the photoconductor faces and meets the predetermined position of the sheet wound around the sheet.

After the yellow toner image on the photoconductor is transferred onto the sheet by the action of the transfer charger 113, the surface of the photoconductor is cleaned by the cleaner 105 to prepare for the image formation of the next color. 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 sufficiently large so that the developing device can be switched in time and the toner image of the previous color and the toner image of the next color are superposed.

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 the colors have been transferred, the sheet 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.

[0009]

In the above-mentioned conventional apparatus, the transfer drum is used for aligning and superposing the toner images of different colors. By rotating this transfer drum at the same speed with respect to the photoconductor, the positions of the toner images of the respective colors when forming a color image are matched. However, in the above configuration, since it is necessary to wind the paper around the transfer drum, the diameter of the transfer drum must be a certain size or more, and the structure is very complicated, so that the device is large-scale. It was.

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

Further, when the OHP is formed, if the fixing is performed at a speed sufficiently slower than the speed of the process, a beautiful OHP having excellent transparency can be formed. However, in the conventional device, the paper conveyance speed must be reduced from the time when the paper is completely peeled off from the transfer drum, so the distance between the transfer drum and the fixing device must be the maximum paper length or more. Further, there is a problem that the device becomes larger.

Furthermore, there is a problem that maintenance such as replacement and repair is very difficult because the structure of the photosensitive member and the developing device for four colors is complicated and large-scaled.

In view of the above problems, the present invention provides a color electrophotographic apparatus which is small in size and has a simple structure to obtain a beautiful color image and is excellent in maintainability.

[0014]

In order to solve the above-mentioned problems, a color electrophotographic apparatus of the present invention includes a plurality of movable units including at least a photosensitive drum and a developing device having toners of different colors. And an image forming unit, a transfer belt that reciprocates on a transfer sheet and transfers toner images of different colors in a superimposed manner on the transfer sheet, an exposing unit, and a fixing unit. Is a color electrophotographic apparatus that sequentially moves to the exposure position to form an image, and after the necessary toner image is transferred, at the time of fixing, the moving speed of the transfer belt is operated at a speed different from the speed at which the image is formed. It is a color electrophotographic apparatus having a mode.

Further, the color electrophotographic apparatus of the present invention for solving the above-mentioned problems includes a plurality of movable image forming units including at least a photosensitive drum and a developing device having toners of different colors. The image forming unit is a color electrophotographic apparatus which comprises a transfer belt on which a transfer sheet is placed and which reciprocates, and an exposure unit, and the image forming unit sequentially moves to a single exposure position facing the transfer belt to form an image. Further, the transfer belt is a color electrophotographic apparatus in which the transfer belt is in a position not in contact with the image forming unit except the photosensitive drum of the image forming unit in the exposure position.

Further, a color electrophotographic apparatus of the present invention for solving the above-mentioned problems includes a plurality of movable image forming units including at least a photosensitive drum and a developing device having toners of different colors. The image forming unit is a color electrophotographic apparatus which comprises a transfer belt on which a transfer sheet is placed and which reciprocates, and an exposure unit, and the image forming unit sequentially moves to a single exposure position facing the transfer belt to form an image. Thus, the plurality of image forming units is a color electrophotographic apparatus that can be pulled out from the apparatus as a unit.

Further, in the color electrophotographic apparatus of the present invention for solving the above-mentioned problems, at least a plurality of moving members including a photoconductor drum, a developing device having toners of different colors, and a cleaner for the photoconductor drum are provided. Possible image forming unit, and a transfer belt that reciprocates on a transfer paper,
A color electrophotographic apparatus comprising a cleaner for the transfer belt and an exposure unit, wherein the image forming unit sequentially moves to a single exposure position facing the transfer belt to form an image, and at least the exposure unit In the color electrophotographic apparatus, the cleaner of the image forming unit and the cleaner of the transfer belt in the position are connected to the same waste toner reservoir.

Furthermore, the color electrophotographic apparatus of the present invention for solving the above problems is composed of a plurality of image forming units each including at least a photosensitive drum and a developing device having a toner of a different color. A group of possible image forming units, a transfer belt that reciprocates on a transfer sheet, and an exposure unit, and each of the image forming units sequentially moves to a single exposure position facing the transfer belt to form an image. Is a color electrophotographic apparatus for performing the above, and which is attached to the image forming unit group and has a discharging unit at a position facing the transfer belt.

[0019]

According to the present invention, with the above-described structure, after the transfer paper on the transfer belt is reciprocally moved, image formation and transfer are sequentially performed by the image forming units of respective colors and the images are overlapped. By lowering the transport speed and performing sufficient fixing, a beautiful color image can be created with a simple and compact structure.

Further, the transfer belt is configured so as not to come into contact with a portion other than the photosensitive drum of the image forming unit at the exposure position, thereby providing an apparatus having a simple structure and easy to maintain.

Further, the image forming unit can be pulled out to the outside of the apparatus as a whole, so that an apparatus having excellent maintainability such as replacement and maintenance of the image forming unit is provided.

Furthermore, the discharged toner from the image forming unit and the discharged toner from the transfer belt are processed in the same discharged toner reservoir, so that the maintainability is improved with a simple structure.

Further, the present invention provides an excellent color electrophotographic apparatus capable of beautiful superimposing transfer with a simple structure by providing a charge eliminating means attached to the image forming unit group.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrophotographic apparatus of the present invention will be described below with reference to the drawings.

An example of such a device will be described with reference to FIG. FIG. 1 shows only the printer section for forming an image in the color electrophotographic apparatus of the present invention.

First, the printer section has four sets of image forming units 1Bk, 1Bk for black, cyan, magenta, and yellow.
C, 1M, and 1Y are arranged side by side. Since each image forming unit is made of the same constituent member except for the developer contained therein, the image forming unit for magenta will be described and the other colors will be omitted for simplification of description. FIG. 2 shows the magenta image forming unit 1M in detail.

In FIG. 2, 9 is an organic photosensitive drum in which phthalocyanine is dispersed in a polyester binder resin,
Reference numeral 10 denotes a non-rotating magnet that is fixed coaxially with the photoconductor 9,
Reference numeral 1 is a corona charger for negatively charging the photoconductor, 12 is a grid electrode for controlling the charging potential of the photoconductor, 13 is a laser beam scanning light, and 14 is a developer hopper.

Inside the developer hopper 14, an iron powder carrier 2 having a particle size of 100 μm, the surface of which is coated with a silicone resin, is used.
A two-component developer 26, which is a mixture of 4 and toner 25, was put in and attached to the surface of the photoconductor 9 by magnetic force. The toner used is one in which a pigment is dispersed in polyester resin 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 inside thereof, 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
The magnetic flux density on the surface and the collecting electrode roller surface is 800 Gs, respectively. The photoconductor 9 has a diameter of 30 mm and is rotated in the direction of the arrow at a peripheral speed of 120 mm / s to collect the recovery electrode roller 17.
Had a diameter of 16 mm and was rotated in the direction of the arrow at a peripheral speed of 100 mm / s.

Reference numeral 27 is a cleaner for cleaning the toner remaining on the surface of the photoreceptor after transfer. Reference numeral 28 denotes a static eliminator, which acts to neutralize the paper and the transfer belt immediately below at a timing described later.

The operation of the image forming unit configured as described above will be described below with reference to FIG. The photoreceptor 9 is set to a corona charger 11 (applied voltage-4 kV, grid 12
Of -500V) was charged to -500V. The photoconductor 9 was irradiated with laser beam scanning light 13 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.
Was magnetically attached in the developer hopper 14. Next, the photoconductor 9 was passed in front of the electrode roller 17. Photoconductor 9
When passing through the uncharged area of 750V0-, a DC voltage of 0V is superposed on the electrode roller 17 by an AC high voltage power source 18.
An AC voltage (frequency 1 kHz) of p (peak-to-peak 1.5 kV) was applied. After that, when the photoconductor 9 charged with −500V and having the electrostatic latent image written thereon passes therethrough, a 750V 0-p (peak-to-peak) in which a DC voltage of −350V is superposed on the electrode roller 17 by an AC high-voltage power source 18. An alternating voltage (frequency 1 kHz) of 1.5 kV) was applied. Then, the toner attached to the carrier and the charged portion of the photoconductor 9 was collected by the electrode roller 16, and the negative-positive inverted toner image remained only on the image portion on the photoconductor 9. The toner adhering to the electrode roller 16 rotating in the direction of the arrow is scraped off by the scraper 19, and the developer hopper 14 again.
It was returned to the inside and used for the next image formation.

In this way, a magenta toner image is obtained on the photosensitive member 9. Developing devices other than magenta 9BK, 9
The C and 9Y have the same configuration and operate.

The configuration of the printer unit will be described again with reference to FIG. Image forming units 9B arranged side by side
The k, 9C, 9M, and 9Y are movable in the lateral direction as a whole, and the image forming units are sequentially located at the image forming position 50 of the transfer belt 31, which faces the transfer portion 33 slightly pushed up by the belt regulating member 32. be able to.

A laser exposure device 3 generates a laser beam scanning light 13 which is modulated by a signal input to the printer unit, which is reflected by the mirrors 4 and 5 and is emitted from the image forming unit at the image forming position 50. The photoconductor is irradiated to form a latent image. In the state of FIG. 1, it acts on the black image forming unit 1BK.

Numeral 8 is a static elimination lamp fixed to the main body, and is located at a position where the surface of the image forming unit at the image forming position 50 after the cleaning of the photoreceptor is irradiated.

The transfer belt 31 is made of an endless belt-shaped polyester film having a thickness of 100 μm, is wound around a driving roller 34 and a roller 35, and the surface of the transfer belt 31 adsorbs a sheet so that the transfer belt 31 can reciprocate. Here, in the present embodiment, the distance between the drive roller 34 and the roller 35 is set to be slightly longer than the length of the A4 sheet in the lateral direction. At the right end of the transfer belt, an adsorption charger 37 for adsorbing the paper fed from the paper feed unit 36 to the polyester film is provided, the transfer charger 33 at the transfer unit 33, and the transfer belt 38 at the left end. A sheet of paper that is peeled off and sent to the left side and a static eliminator 39 for eliminating static electricity of the transfer belt are arranged.

Reference numeral 40 denotes a toner receiver for receiving the discharged toner sent from the cleaner portion 27 in which each image forming unit operates at the image forming position, and 41 denotes a belt cleaner portion for cleaning the transfer belt and a belt cleaner portion including the discharged toner reservoir. ..
The toner receiver 40 includes a connecting portion 42 and a belt cleaner portion 41.
The toner discharged from each image forming unit is collected in the belt cleaner unit 41.

The transfer belt 31, the transfer charger 38, the belt cleaner 41 and the like can be moved to the positions indicated by the dotted lines as a whole in case of paper jam.

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 configuration of the electrophotographic apparatus of the present invention. In the present embodiment, the transfer portion of the transfer belt 31 is slightly raised from the other portion and brought into contact with the photosensitive member of the image forming unit at the exposure position. You may lower it slightly only when.

Next, when forming a color image of A4 size,
The operation of this device will be described. A4 paper (not shown) is fed in the lateral direction from the paper feeding unit 36, and while being attracted to the transfer belt 31 by the action of the adsorption charger 37, is placed on the transfer belt and leftward at a constant speed (hereinafter, in order). Call it direction). At this time, the paper is surely adsorbed to the transfer belt 31, so that the positions of the transfer belt and the paper do not deviate from each other even when the transfer belt is reciprocally moved, as will be described later, and the toner images of the respective colors are easily aligned. ..

First, the image forming unit is at a position as shown in FIG. 1, the black image forming unit 1BK is at the image forming position 50, and faces the transfer portion 33. The laser exposure device 3 inputs the black signal light to the image forming unit 1BK at the same timing as the sheet is carried on the transfer belt from the right side, and the image is formed by the black toner. At this time, the image forming speed of the image forming unit 1BK (peripheral speed of the photoconductor) and the moving speed of the transfer belt are set to be the same, and at the same time when the image is formed, the transfer charger is moved along with the movement of the paper. By the action of 38, the black toner image is transferred onto the paper. Immediately after all the black toner images have been transferred and the trailing edge of the paper has passed through the transfer section, the transfer belt is temporarily stopped and then moved in the reverse direction to the forward direction (hereinafter, reverse direction). Move at a speed greater than the moving speed. At this time, since the length of the transfer belt is sufficiently long, the leading edge of the paper is in the vicinity of the driving roller and is not peeled off from the transfer belt.

On the other hand, almost at the same time when the transfer belt starts moving in the reverse direction, the entire image forming unit group 1BK, 1C, 1M, 1Y moves integrally to the left in FIG. 1 and reaches the position shown in FIG. Is set. At this time, a high AC voltage acts on the static eliminator 28 and the transfer charger 38 attached to the image forming unit 1BK, and the static charge is removed while the sheet carrying the toner image and the transfer belt move and pass in opposite directions.

During this time, the bottom portion (see FIG. 2) of the image forming unit other than the photosensitive member is located above the photosensitive member, so that the black toner image on the paper does not contact the image forming unit and is disturbed.

After the leading edge of the paper has passed the transfer portion 33 to the right,
The image forming unit 1C is moved to the image forming position 50, and the transfer belt is again moved in the forward direction at a constant speed. Similar to the previous case, this time, the laser exposure device inputs the signal light to the image forming unit 1C with the cyan signal to form and transfer the cyan toner image. At this time, the start of writing the signal light is set in timing so that the next cyan toner image is positionally aligned with the black toner image on the paper.

The same operation as described above is performed for magenta and yellow, and toner images of four colors are positionally aligned and superposed on each other to form a color image. After the last transfer of the yellow toner image, the transfer belt continues to move in the forward direction as it is, and the sheet on which the color image is formed is discharged by the static eliminator 3.
The toner image is separated from the transfer belt while being discharged by the action of 9, and the toner image is fixed by the fixing device, and is discharged to the outside of the apparatus through the discharge roller.

Since the distance between the driving roller 34 and the roller 35 of the transfer belt is set to be slightly larger than the total length of the image forming unit group in the horizontal direction in FIG. Even if the image forming unit group moves integrally until each of the image forming units reaches the image forming position, it does not hit the adsorption charger 37 and the static eliminator 39.

When the paper is peeled from the transfer belt,
Since the charge is sufficiently removed, a beautiful color image can be obtained without the toner scattering on the paper.

Further, immediately after the transfer of the final toner image is completed, the leading edge of the paper has not reached the fixing device yet. Therefore, at this time, the operation mode is changed to change the transfer belt forward speed and the fixing device speed. It is possible to fix at a low speed by lowering the speed to a low speed, which makes it possible to create a glossy color image and a beautiful OHP having excellent transparency.

On the other hand, the surface of the photoconductor, which is operating at the image forming position, is cleaned by the cleaner 27 (see FIG. 2) after the transfer, and the toner discharged at that time passes through the toner receiver 40 and the connecting portion 42 and the belt cleaner portion. Collected at 41. Further, the toner scattered on the transfer belt is also cleaned by the belt cleaner during the operation.

The above is the description of the operation of the electrophotographic apparatus of this embodiment in the A4 color mode. Next, the operation in the single color mode will be described. In the monochromatic mode, the image forming unit of a predetermined color is first moved to the image forming position before the sheet reaches the transfer position. Next, in the same manner as before, image formation and transfer of a predetermined color are performed, and this time, after transfer, the transfer belt continues to move in the forward direction, fixing and discharging the paper. Therefore, in the single-color mode, for example, A3 paper having a size of A4 or larger can be used.

Next, the structure of this apparatus for replacing the image forming unit will be described. The image forming unit is set so as to be in the position shown in FIG. 3 when the apparatus is on standby or stopped, other than during image formation.

FIG. 4 shows a state in which one of the image forming units 1Y is pulled out of the apparatus when the apparatus is stopped. As described above, when the apparatus is stopped, the image forming unit is in a position where it does not contact the transfer belt portion.
It is possible to easily pull out like. The first support 51 that supports the image forming unit groups 1BK to 1Y is movable in the apparatus depth direction with respect to the second support 52 that supports the image formation unit groups 1BK to 1Y. Is movable in the lateral direction of the device along a rail 53 fixed to the main body. When the image forming units are replaced, as shown in FIG. 4, first, the image forming unit group is integrally drawn out to the front side of the apparatus, and then each image forming unit is independently pulled out to the upper side.

Therefore, in this configuration, since each image forming unit including the photoconductor can be independently adjusted externally, it is possible to easily replace, for example, a unit which has already been adjusted at the time of factory shipment on site.

The above is a detailed description of the present invention.

[0057]

As described above, according to the present invention, during the reciprocating movement of the transfer paper on the transfer belt, the images are sequentially formed and transferred by the image forming units of respective colors, and the images are superposed, and then transferred when the OHP is produced. By slowing down the paper transport speed and performing sufficient fixing,
It creates a beautiful color image with a simple and compact structure.

Further, the transfer belt is configured so as not to come into contact with a portion other than the photosensitive drum of the image forming unit at the exposure position, thereby providing an apparatus having a simple structure and easy to maintain.

Further, the image forming unit can be pulled out of the apparatus as a unit, so that the apparatus having excellent maintainability such as replacement and maintenance of the image forming unit is provided.

Furthermore, the discharged toner from the image forming unit and the discharged toner from the transfer belt are processed in the same discharged toner reservoir, so that the maintainability is improved with a simple structure.

Further, by providing a destaticizing means attached to the image forming unit group, it is possible to provide an excellent color electrophotographic apparatus capable of beautiful superposition transfer with a simple structure.

[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 diagram showing a configuration of one image forming unit of the color electrophotographic apparatus in the embodiment of the present invention.

FIG. 3 is a diagram showing the position of the image forming unit in the state 1 of the color electrophotographic apparatus in the embodiment of the invention.

FIG. 4 is a diagram showing a state when the image forming unit of the color electrophotographic apparatus according to the exemplary embodiment of the present invention is being replaced.

FIG. 5 is a schematic view of a conventional electrophotographic developing device.

[Explanation of symbols]

 3 Laser exposure device 1Bk, 1C, 1M, 1Y Image forming unit 9 Photoreceptor 28 Static eliminator 31 Transfer belt 33 Transfer charger 40 Belt cleaner section

Claims (6)

[Claims] 1. A plurality of movable image forming units each including at least a photosensitive drum and a developing device having a toner of a different color, and a reciprocating movement of a transfer paper to transfer toner images of different colors. A color electrophotographic apparatus comprising a transfer belt for transferring and superposing on a sheet of paper, an exposing unit, and a fixing unit, wherein each of the image forming units sequentially moves to a single exposure position to form an image, and Color electrophotographic apparatus having a mode in which the transfer belt is moved at a speed different from that at the time of image formation at the time of fixing after transferring the toner image. 2. A plurality of movable image forming units, each of which includes at least a photosensitive drum and a developing device having a toner of a different color, a transfer belt that reciprocates on a transfer paper, and an exposure unit. The image forming unit is a color electrophotographic apparatus that sequentially moves to a single exposure position facing the transfer belt to form an image, and the transfer belt is an image forming unit located at the exposure position. Color electrophotographic apparatus in a position not in contact with the image forming unit except for the photosensitive drum 3. The color electrophotographic apparatus according to claim 1, wherein none of the image forming units is located at the exposure position except during image formation. 4. A plurality of movable image forming units each including at least a photosensitive drum and a developing device having a toner having a different color, a transfer belt that reciprocates on a transfer paper, and an exposure unit. The image forming unit is a color electrophotographic apparatus that sequentially moves to a single exposure position facing the transfer belt to form an image, and the plurality of image forming units are integrally withdrawn from the apparatus. Possible color electrophotographic device. 5. A plurality of movable image forming units including at least a photoconductor drum, a developing device having toners of different colors, and a cleaner for the photoconductor drum, and a transfer belt reciprocating on which a transfer paper is placed. A color electrophotographic apparatus that comprises an cleaner for the transfer belt and an exposure unit, and the image forming unit sequentially moves to a single exposure position facing the transfer belt to form an image, and A color electrophotographic apparatus in which at least the cleaner of the image forming unit and the cleaner of the transfer belt, which are in the exposure position, are connected to the same waste toner reservoir. 6. A movable image forming unit group composed of a plurality of image forming units each including at least a photosensitive drum and a developing device having a toner having a different color, and a transfer which reciprocates on a transfer paper. The image forming unit comprises a belt and an exposing unit, and the image forming unit is a color electrophotographic apparatus that sequentially moves to a single exposure position facing the transfer belt to form an image. A color electrophotographic apparatus, which is attached and has a discharging means at a position facing the transfer belt.