JPH10312096A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operability from one direction and to facilitate jamming processing in a transfer area by moving a developing means to the side of an image forming device together with an image forming body inside which an image exposure means is integrally arranged and making the transfer area open. SOLUTION: An engaging member 103b is disengaged from engaging grooves 101a and 102a and an upper cover 103 is opened with a supporting shaft 103a as fulcrum so as to open the upper part of the device. A processing unit 300a is constituted by coupling a drum unit 301 where a photoreceptor drum 10, a scorotron electrifier 11 and a cleaning device 19 are integrated with a right- side developing unit 302 where right-side C and K developing devices 13 are integrated through a unit coupling member 304a, and pulled out in a right direction on a guide plate 104. In such a state, a transfer part 140 functioning as a transfer means is opened, and the transfer area is set open, so that the jamming processing is easily performed. The drum unit 301 is pulled out from the opening part on the upper part of a device main body so as to execute maintenance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a method of forming a multi-color image, a single color image formed on each image forming body is provided with the same number of image forming bodies, charging means, developing means and the like as the number of colors required for image formation. Color image forming apparatus that forms a color image by superimposing the toner image on a transfer material, or a color image forming apparatus that rotates the image forming body a plurality of times and repeats charging, image exposure, and development for each color to form a color image Alternatively, there is known a color image forming apparatus which forms a color image by sequentially performing charging, image exposure, and development for each color within one rotation of the image forming body.

However, each of the above image forming apparatuses is provided with the same number of image forming bodies, charging means, developing means, etc. as the number of colors required for image formation, and superposes a single color toner image formed on each image forming body on a transfer material. A color image forming apparatus that forms a color image together has a drawback that the volume of the apparatus is increased due to the necessity of transporting a plurality of image forming bodies and a transfer material. A color image forming apparatus that forms a color image by repeating charging, image exposure, and development has a limitation that although the volume is reduced, the size of the formed image is limited to the surface area of the image forming body or less. .

In this regard, a color image forming apparatus which forms a color image by sequentially performing charging, image exposure and development for each color within one rotation of the image forming body has no restriction on the size of the image and has a high speed image. There are advantages such as enabling formation. Further, an apparatus in which a light-transmitting substrate is used as a substrate of an image forming body and an image exposing means is arranged inside the image forming body to reduce the size of the apparatus has been proposed, for example, in Japanese Patent Application Laid-Open No. 5-307307. .

[0005]

However, in the color image forming apparatus proposed above, a plurality of image exposing means are provided inside the image forming body to reduce the size of the apparatus. Since a plurality of sets of developing means and charging means are arranged in the image forming apparatus, the structure becomes complicated. Processing becomes difficult. Also,
The operability in one direction is poor when performing jam clearance or replacing the image forming body.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color image forming apparatus which solves the above-mentioned problems, has good operability in one direction, and can easily perform jam processing and replacement of an image forming body.

[0007]

An object of the present invention is to arrange a plurality of sets of charging means, image exposing means and developing means around a drum-shaped image forming body, and to form a toner image by rotating the image forming body. In a color image forming apparatus, which is formed by being superimposed on a formed body and then collectively transferred to a transfer material by a transfer unit and fixed by a fixing unit, the image exposing unit is integrally disposed inside the image formed body. Disposing the transfer means in the lower part, further arranging the plurality of developing means on both sides, and opening the transfer area of the transfer means by moving the developing means to the side together with the image forming body. A first aspect of the present invention is achieved by a characteristic color image forming apparatus.

The above object is also achieved by arranging a plurality of sets of charging means, image exposing means, and developing means around a drum-shaped image forming member, and rotating the image forming member to form a toner image on the image forming member. In the color image forming apparatus, which is formed by superimposing and then collectively transferred by a transfer unit to a transfer material fed by a feeding unit and fixed by a fixing unit, the image forming body is
The image exposure unit is integrally disposed inside, the transfer unit is disposed below, the plurality of developing units are further disposed on both sides, and the developing unit is movable to the side, and the color This is achieved by a color image forming apparatus characterized in that the image forming body is attached to and detached from the upper part of the image forming apparatus (second invention).

[0009]

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

An image forming process and each mechanism of a color image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional configuration diagram showing an embodiment of the color image forming apparatus of the present invention, and FIG.
FIG. 3 is a side sectional view of the image forming unit, FIG. 3 is a diagram illustrating a developing unit, FIG. 4 is a perspective view illustrating a method of attaching an upper cover, and FIG. 5 is an image from a color image forming apparatus. It is a figure which shows one Embodiment of the removal method of a molded object.

Referring to FIGS. 1 to 3, a photosensitive drum 10 as an image forming body is provided with a cylindrical base formed of a light-transmitting member such as optical glass or transparent acrylic resin, for example, inside. A light-transmitting conductive layer and a photosensitive layer such as an organic photosensitive layer (OPC) are formed on the outer periphery of the substrate, and are rotated clockwise in FIG. 1 in a grounded state.

In the present embodiment, it is sufficient that the photoconductive layer of the photosensitive drum has an exposure light amount capable of providing an appropriate contrast. Therefore, the light transmittance of the light-transmitting substrate of the photosensitive drum in this embodiment does not need to be 100%, and may have a characteristic that a certain amount of light is absorbed when the exposure beam is transmitted. As the material of the translucent substrate, soda glass, Pyrex glass, borosilicate glass or acrylic used for general optical members, fluorine,
Various translucent resins such as polyester, polycarbonate, and polyethylene terephthalate can be used. In addition, as the light-transmitting conductive layer, indium tin oxide (IT
O), tin oxide, lead oxide, indium oxide, copper iodide,
A light-transmissive metal thin film made of Au, Ag, Ni, Al, or the like is used. As a film forming method, a vacuum deposition method, an active reaction deposition method, various sputtering methods, various CVD methods,
A dip coating method, a spray coating method, or the like is used. Also,
As the photoconductor layer, amorphous silicon (a-S
i) An alloy photosensitive layer, an amorphous selenium alloy photosensitive layer, or various organic photosensitive layers (OPC) can be used.

The photosensitive drum 10, as shown in FIG.
Flange members 10a and 1 at both ends for engaging and fixing it
The photoreceptor unit 0b is rotatably supported by the bearings B1 and B2 fitted to the flange members 10a and 10b at both ends of the drum shaft 30 mounted and fixed to the apparatus main body. 100 is formed, and the gear G integrated with the flange member 10b is driven by meshing with a drive gear (not shown) on the apparatus main body side, so that a constant speed in a predetermined direction, for example, 250 mm / sec.
Rotated at c. WA is a lead wire from a light emitting element (LED) of an image exposure unit described later. The drum shaft 30 is attached and fixed to a side wall of the drum unit 301 (in the case of FIG. 5) described later or a side wall of the housing of the apparatus main body (in the case of FIG. 6).

Scorotron charger 11 as charging means
Are used in image forming processes of yellow (Y), magenta (M), cyan (C), and black (K), and face the photosensitive drum 10 in a direction orthogonal to the moving direction of the photosensitive drum 10. Attached to the photosensitive drum 1
0, a control grid maintained at a predetermined potential with respect to the above-mentioned organic photosensitive layer, and a sharp electrode as the discharge electrode 11a, and a corona discharge having the same polarity as that of the toner to perform a charging action (in this embodiment, a negative charge). ) To apply a uniform potential to the photosensitive drum 10. Discharge electrode 1
Other needle electrodes may be used as 1a.

Exposure optical system 1 as image exposure means for each color
Reference numeral 2 denotes an exposure position on the photosensitive drum 10 provided between the discharge electrode 11a of the scorotron charger 11 and the developing position of the developing device 13 on the upstream side in the rotation direction of the photosensitive drum with respect to the developing sleeve 131. It is arranged in a state where

The exposure optical system 12 has an LE as a light emitting element arranged in the main scanning direction in parallel with the axis of the photosensitive drum 10.
A linear exposure element 12a in which a plurality of D (light emitting diodes) are arranged in an array, and a light converging light transmitter (selfoc lens) 12b as an imaging element are provided with a lens holder 12
The exposure optical system 12 for each color is attached to the holding member 20 and accommodated in the base of the photosensitive drum 10. As described above, as shown in FIG. 2, the photosensitive drum 10 and the exposure optical system 12 are formed as an integral photosensitive unit 100. Image data of each color read by a separate image reading device and stored in the memory is sequentially read from the memory and input to the exposure optical system 12 for each color as an electric signal.

As the exposure element, FL (phosphor emission), EL (electroluminescence), PL (plasma discharge) and the like are used. The emission wavelength of the light emitting element used in this embodiment is preferably in the range of 780 to 900 nm, which is generally high in the transmittance of the Y, M, and C toners. A shorter wavelength of 400 to 700 nm which does not have sufficient translucency may be used.

A developing unit 13 provided in accordance with the color sequence in which an image is formed and a rotating photosensitive drum is provided in accordance with the color sequence.
In the present embodiment, the developing units 13 for Y and M are on the left side of the photosensitive drum 10 with respect to the rotation direction of the photosensitive drum 10 indicated by the arrow in FIG. Are arranged on the right side of the photosensitive drum 10 and the Y and M developing devices 1
3 and a scorotron charger 11 for C and K above the developing casing 138 of the developing unit 13 for C and K, respectively.
Is arranged. As shown in FIG. 1, each scorotron charger 11 can be mounted integrally with the developing device 13.

The developing device 13 as a developing means for each color includes
The two-component developers of yellow (Y), magenta (M), cyan (C), and black (K) are accommodated respectively, and a predetermined gap is maintained with respect to the peripheral surface of the photosensitive drum 10, respectively.
At the developing position, the photosensitive drum 10 rotates in the same direction as the rotating direction of the photosensitive drum 10, for example, a thickness of 0.5 mm to 1 mm and an outer diameter of 15 m.
The developing sleeve 131 is formed of a nonmagnetic stainless steel or aluminum material having a cylindrical shape of m to 25 mm.

The developing device 13 as a developing means for each color is configured as follows, for example, as shown in FIG.

The fixed magnet 132 is included in the developing sleeve 131, and alternately arranges N and S magnetic poles (not shown), is fixed concentrically with the developing sleeve 131, and applies a magnetic force to the peripheral surface of the non-magnetic sleeve. Let it. Thin layer forming member 133
Is an elastic plate-shaped member such as foamed rubber or urethane rubber that regulates the layer thickness of the two-component developer on the peripheral surface of the developing sleeve 131. Pressed evenly. Developing sleeve 131
The scraper 134, which is a removing means for removing the two-component developer from above, has one end of the long side of the belt-like shape.
It is made of a plate-like elastic member such as SUS, urethane rubber, or the like, which is provided so as to be pressed in parallel with 31. The stirring screws 136 and 137 rotate at a constant speed in directions opposite to each other, and stir and mix the toner and the carrier in the developing device 13 to form a two-component developer containing a predetermined toner component evenly. Further, the two-component developer is supplied to the stirring section by the supply roller 135, or is transported and supplied to the developing sleeve 131 from the stirring section. 138 is a developing casing.

The developing unit 13 is set in a gap of a predetermined value from the photosensitive drum 10 by an abutting roller (not shown), for example, 100 μm.
In the developing operation of the developing unit 13 for each color, a developing bias to which a DC voltage or an AC voltage AC is applied is applied to the developing sleeve 131, so that the developing unit 13 accommodates the developing unit. Jumping development with a component developer is performed, and a DC bias of the same polarity as the toner (minus polarity in the present embodiment) is applied to the negatively charged photosensitive drum 10 that grounds the transparent conductive layer to expose Non-contact reversal development for attaching toner to the portion is performed. At this time, the precision of the development interval needs to be about 20 μm or less in order to prevent image unevenness.

The developing unit 13 for each color described above applies the voltage of the developing bias voltage to the electrostatic latent image on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure optical system 12. In a non-contact state by a non-contact development method by application, reversal development is performed with toner having the same polarity as the charged polarity (the photoreceptor is negatively charged and a negative polarity toner in this embodiment).

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

A gear G provided on the rear flange 10b of the photosensitive drum 10 is rotated by the start of a photosensitive drum drive motor (not shown) at the start of image recording, and the photosensitive drum 10 is turned clockwise as indicated by an arrow in FIG. And at the same time, a potential is applied to the photosensitive drum 10 by the charging action of the Y scorotron charger 11 disposed below the developing casing 138 of the yellow (Y) developing device 13 to the left of the photosensitive drum 10. Be started.

After a potential is applied to the photosensitive drum 10, the Y exposure optical system 12 starts exposure with the first color signal, that is, an electric signal corresponding to the Y image data, and the surface of the photosensitive drum 10 is rotated by rotational scanning. An electrostatic latent image corresponding to the Y image of the original image is formed on the photosensitive layer.

The latent image is reversal-developed by the Y developing device 13 in a state where the developer on the developing sleeve is not in contact with the developer, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is placed on the yellow (Y) toner image, and further on the left side of the photosensitive drum 10 and above the yellow (Y), a magenta (M) developing device 1 is formed.
A potential is applied by the charging action of the magenta (M) scorotron charger 11 disposed below the third developing casing 138, and the second color signal of the M exposure optical system 12, that is, electricity corresponding to M image data. Exposure with a signal is performed, and a magenta (M) toner image is sequentially superimposed on the yellow (Y) toner image by non-contact reversal development by the M developing unit 13.

By the same process, the developing casing 13 of the developing device 13 for cyan (C) is located on the right side of the photosensitive drum 10.
The cyan (C) toner image corresponding to the third color signal is further exposed by the cyan (C) scorotron charger 11, the exposure optical system 12 of C, and the developing device 13 of C, which are disposed above the cyan (C). The black (K) scorotron charger 11, the exposure optical system 12, and the developing device 13 are disposed on the right side of the body drum 10 and below the developing casing 138 of the black (K) developing device 13 below the C. Are sequentially superimposed, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10.

The exposure optical system 12 for Y, M, C and K
Exposure to the organic photosensitive layer of the photosensitive drum 10 is performed from the inside of the drum through the above-described translucent substrate. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the same exposure as the image corresponding to the first color signal is performed. It is possible to form an electrostatic latent image.

Transfer paper P, which is a transfer material, is sent out from a paper feed cassette 15 serving as a transfer material storage means by a feed roller 15a, fed by a feed roller 15b, and conveyed to a timing roller 15c. The recording paper P is synchronized with the color toner image formed on the photosensitive drum 10 by the driving of the timing roller 15c, and a transfer belt 14a stretched between a driving roller 14d and a driven roller 14e is provided. The photosensitive drum 10 and the transfer belt 14 are transferred by the transfer belt device 140 as a transfer means.
is transferred to a transfer area 14b formed between the transfer area 14a and the transfer area 14a. The image on the peripheral surface of the photosensitive drum 10 is collectively transferred onto the recording paper P by the transfer device 14c.

The recording paper P separated from the transfer belt device 140 by the curvature separation of the driving roller 14d is conveyed to a fixing device 17 composed of two rollers having a heater inside at least one of the rollers. Fixing roller 17
a and the pressure roller 17b apply heat and pressure to fix the adhered toner on the recording paper P, and the recording paper P is sent by the paper discharge roller 18 and discharged to a tray outside the apparatus. You.

On the other hand, the photosensitive drum 10 from which the recording paper P has been separated is rubbed on the surface of the photosensitive drum 10 by a cleaning blade 19a in a cleaning device 19 to remove and clean residual toner to form a toner image of a document image. To continue. The waste toner scraped off by the cleaning blade 19a is discharged to a waste toner container (not shown) by the toner conveying screw 19b. After the cleaning is completed, the cleaning blade 19a is kept separated from the photosensitive drum 10 in order to prevent damage to the photosensitive drum 10.

In the above description, the developing device 13 as the developing means uses a two-component developer, but it is of course possible to use a developing means using a one-component developer.

According to FIG. 1 or FIG.
It is an upper cover that can be opened and closed with 03a as the center of rotation. An arm 103d extends from the center of the upper cover 103, and a circular engaging member 103b having a H-shaped cross section is attached to both ends of the arm 103d. An engaging member 103b is fitted into an engaging groove 103a, 102a provided substantially at the center at the upper end of the front and rear side plates 101, 102 of the apparatus main body. Fixed to The main body of the color image forming apparatus whose upper center is opened is reinforced by the arm 103d in which the upper center of the apparatus housing is integrated with the engagement member 103b and the arm 103d is stretched over the housing as a stay. Both side plates 101, 10
The main body of the apparatus is reinforced by the arm 103d fitted into the arm 2, so that the registration of the superposed image by the image exposure means can be performed with high precision.

According to FIG. 5, the engagement grooves 101a, 102a
The engagement member 103b is further removed, and the upper cover 103 is opened with the support shaft 103a as a fulcrum, and the upper part of the apparatus is opened. A guide plate 104 is opened with the support shaft 104a as a fulcrum, and a stopper 105 stretched over the side plates 101 and 102.
To form a guide plane.

Photoconductor drum 10, scorotron charger 1
5 and a right developing unit 302 integrating the C and K developing units 13 on the right side of FIG. 5 with a unit connecting member 304a to form a process unit 300a. , The process unit 300a is the guide plate 1
04 is drawn rightward in FIG. In this state, the transfer unit 140 as a transfer unit is opened, and the transfer area 14b is opened, so that the jam processing is facilitated. Further, the unit connecting member 304a is detached, and the drum unit 301 is pulled out from the opening in the upper part of the apparatus main body.
01 maintenance and replacement are performed.

A left developing unit 303 is formed integrally with the Y and M developing units 13 on the left side of FIG. 5, and a locking member (not shown) is removed from an opening in the upper part of the apparatus to form the developing unit 303. Then, maintenance and replacement of the Y and M developing units 13 are performed. Similarly, the not-shown locking member is removed from the opening in the upper part of the apparatus, and the transfer unit 140 or the fixing device 17 is taken out.
7 is maintained or replaced.

In the above description, it is possible to provide a handle 301a indicated by a dashed line in FIG. 5 on the drum unit 301 to facilitate pulling out of the drum unit 301.

As described above, since the upper part of the apparatus main body is opened, the operability in one direction on the right side of the apparatus main body in FIG. 5 is good, and the exchange of the developing means, image forming body, transfer means or fixing means is easy. Become. Further, by moving the developing means to the side of the color image forming apparatus together with the image forming body in which the image exposing means is integrally disposed to open the transfer area, the jam processing in the transfer area becomes easy.

FIG. 6 shows another embodiment of a method for taking out an image forming body from a color image forming apparatus.

The image forming process, the structure, and the mechanism for opening and closing the upper cover are the same as those described with reference to FIGS.

According to FIG. 6, the engagement grooves 101a, 102a
The engagement member 103b is further removed, and the upper cover 103 is opened with the support shaft 103a as a fulcrum, and the upper part of the apparatus is opened. A guide plate 104 is opened with the support shaft 104a as a fulcrum, and a stopper 105 stretched over the side plates 101 and 102.
To form a guide plane.

A right developing unit 302 is formed by integrating the C and K developing units 13 on the right side of FIG. 6, and the developing unit 302 is pulled out on the guide plate 104 rightward in FIG. Maintenance and replacement of the unit 302 are performed.

Photosensitive drum 10, scorotron charger 1
The drum unit 301 in which the cleaning unit 19 and the cleaning unit 19 are integrated, and the left developing unit 303 in which the Y and M developing units 13 shown in FIG. 6 are integrated are connected by a unit connecting member 304b to form a process unit 300b. You.

The unit coupling member 304a is removed, the exposure optical system 12 for each color is included, and the drum shaft 30 on which the photosensitive drum 10 is mounted is connected to the guide grooves 101b and 102b provided on the side plates 101 and 102. The drum unit 301 is removed as a guide, and the drum unit 301 is pulled out upward to perform maintenance or replacement of the drum unit 301. In this state, the transfer unit 140 as a transfer unit is opened, and the transfer area 14b is opened, so that the jam processing is facilitated. Also,
A feed guide plate 15d which constitutes a feeding unit by integrating a roller member facing the timing roller 15c is opened by the timing roller 15c, and the jam processing becomes easier. A handle 301a indicated by a chain line in FIG. 6 may be provided on the drum unit 301, so that the drum unit 301 can be easily pulled out.

The locking member (not shown) is removed, and Y on the left side of FIG.
The left developing unit 303 integrating the developing units 13 and 13 is removed from the opening at the top of the apparatus, and maintenance and replacement of the developing units 13 of Y and M are performed. Similarly, the not-shown locking member is removed from the opening at the top of the apparatus, the transfer unit 140 or the fixing device 17 is taken out, and the transfer unit 140 or the fixing device 17 is maintained or replaced.

As described above, since the upper part of the apparatus main body is opened, the operability in one direction on the right side of the apparatus main body in FIG. 6 is good, and the exchange of the developing means, image forming body, transfer means or fixing means is easy. Become. In particular, the developing means can be moved to the side of the color image forming apparatus, and the image forming body in which the image exposing means is integrally disposed is moved above the color image forming apparatus to detach the image forming body. Thereby, the operability in one direction is good, and the attachment / detachment of the image forming body becomes easy.

[0049]

According to the first aspect, the developing means is moved to the side of the color image forming apparatus together with the image forming body in which the image exposing means is integrally disposed to open the transfer area. The operability in the direction is better, and the jam removal in the transfer area is facilitated.

According to the second aspect, the operability in one direction is good, and the exchange of the image forming body, the transfer means or the fixing means becomes easy.

According to the third aspect, the main body of the color image forming apparatus whose upper center is opened is reinforced and the main body structure is strengthened.

According to the fourth aspect, the developing means can be moved to the side of the color image forming apparatus, and the image forming body in which the image exposing means is integrally disposed is placed above the color image forming apparatus. By moving and attaching and detaching the image forming body, the operability in one direction is good, and the attaching and detaching of the image forming body becomes easy.

According to the fifth aspect, the jam clearance in the feeding means becomes easy.

According to the sixth aspect, the operability in one direction is good, and the transfer means or the fixing means can be easily replaced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating an embodiment of a color image forming apparatus of the present invention.

FIG. 2 is a side sectional view of an image forming unit.

FIG. 3 is a diagram illustrating a developing unit.

FIG. 4 is a perspective view showing a method of attaching an upper cover.

FIG. 5 is a diagram illustrating an embodiment of a method for removing an image forming body from a color image forming apparatus.

FIG. 6 is a diagram illustrating another embodiment of a method for removing an image forming body from a color image forming apparatus.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 14a transport belt 14b transfer area 15d feed guide plate 17 fixing device 100 photoconductor unit 101, 102 side plate 103 upper cover 103b engagement member 103d arm 140 transfer belt device 300a, 300b Process unit 301 Drum unit 302, 303 Developing unit P Recording paper

Claims (6)

[Claims] 1. A plurality of sets of charging means, image exposing means, and developing means are arranged around a drum-shaped image forming member, and a toner image is formed on the image forming member by rotation of the image forming member. Thereafter, in a color image forming apparatus in which the image is exposed to the transfer material by a transfer unit and fixed by a fixing unit, the image exposing unit is integrally disposed inside the image forming body, and the transfer unit is disposed below the image forming body. A color image forming apparatus, further comprising: arranging the plurality of developing units on both sides and moving the developing units together with the image forming body to open a transfer area of the transfer unit. 2. The color image forming apparatus according to claim 1, wherein the image forming body, the transfer unit, or the fixing unit is replaced while the transfer area is open. 3. The color image forming apparatus according to claim 1, wherein the image forming body or the upper cover is integrated with stays on both side plates of the color image forming apparatus main body. 4. A plurality of sets of charging means, image exposing means and developing means are arranged around a drum-shaped image forming body, and a toner image is formed on the image forming body by rotation of said image forming body. After that, in a color image forming apparatus which is collectively transferred to a transfer material fed by a feeding unit by a transfer unit and fixed by a fixing unit, the image exposure unit is integrally disposed inside the image forming body. Disposing the transfer means in the lower part, further arranging the plurality of developing means on both sides, enabling the developing means to move to the side, and attaching and detaching the image forming body from the upper part of the color image forming apparatus. A color image forming apparatus. 5. The color image forming apparatus according to claim 4, wherein said image forming body is taken out and said feeding means is opened. 6. The color image forming apparatus according to claim 4, wherein the transfer unit or the fixing unit is replaced after taking out the image forming body.