JP3366972B2 - Color image forming equipment - Google Patents

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, and a FAX, in which a plurality 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 while rotating.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a multicolored image, an image forming body, a charging means, a developing means, and the like, which are the same in number as the colors necessary for forming an image, are provided, and a single color formed on each image forming body. Color image forming apparatus that forms a color image by superimposing the toner image of the above on a transfer material to form a color image, and forms a color image by repeating charging, image exposure and development for each color by rotating the image forming body a plurality of times. There is known an apparatus or a color image forming apparatus which forms a color image by sequentially performing charging, image exposure and development within one rotation of the image forming body.

However, each of the image forming apparatuses described above is provided with the same number of image exposing means, charging means, developing means and the like as the colors required for image formation, and the monochromatic toner images formed on the photoconductors are respectively superposed on the transfer material. A color image forming apparatus for forming a color image has a drawback that the volume of the apparatus is increased because a plurality of image forming bodies and transfer materials need to be conveyed. On the other hand, by rotating the image forming body a plurality of times, each color A color image forming apparatus that forms a color image by repeating charging, image exposure, and development has a small volume, but has a restriction that the size of an image formed is limited to the surface area of a photoreceptor or less.

In view of this, a color image forming apparatus that forms a color image by sequentially performing charging, image exposure and development within one rotation of the image forming body does not have a restriction on the size of the image and can form an image at high speed. There are advantages such as

[0005]

However, in the apparatus proposed above, a large number of fixed image exposing means are arranged with respect to the image forming body, and the image forming body can be rotated or the image forming body can be attached and detached. It is difficult to do so, and when the image forming body is replaced or maintained, the center positions of the image forming body and the image exposing means are displaced, and the gap between the image exposing means and the image forming body is displaced, so that the image forming of the image exposing means is performed. There is a problem that image blurring occurs due to the position shift. In addition, when the image forming body is replaced or maintained, the center positions of the image forming body and the image exposing means are deviated, and the position of the distance between the image forming means and the image forming means is misaligned, resulting in color misregistration.

The present invention solves the above problems and provides a color image forming apparatus in which the center positions of the image forming body and the image exposing means do not shift when the image forming body is replaced or maintained. The purpose is to do.

[0007]

The above object is to provide a cylindrical image forming body for forming a latent image, a charging means for charging the image forming body around the image forming body, and a charged image. A plurality of pairs of image exposing means for exposing a formed body to form a latent image and developing means for developing a latent image formed on the image forming body to form a toner image are arranged, and one rotation of the image forming body is performed. A plurality of toner images are formed on the image forming body by sequentially repeating the formation of a toner image on the image forming body by charging by the charging unit, image exposure by the image exposing unit, and development by the developing unit. In a color image forming apparatus that transfers the superposed toner images onto a transfer material at once after superposing, the image exposure is performed concentrically with the image forming body so as to surround the outside of the cylindrical image forming body. A cylindrical support member that supports the means Only be achieved by a color image forming apparatus characterized by having a bearing of the support shaft for supporting the image forming body in a cylindrical shape of the center position of the side surface of the support member.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. Note that the description in this section does not limit the technical scope of the claims or the meaning of terms. Further, the following affirmative description in the embodiments of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

The image forming process and each mechanism of the color image forming apparatus of one embodiment of the present invention will be described with reference to FIG. FIG. 1 is a sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

In the color image forming apparatus of this embodiment, a photosensitive drum having a conductive base and a photosensitive layer provided on the outer peripheral surface of a cylindrical substrate is used as an image forming body, and the photosensitive drum is provided outside the photosensitive drum. Image exposure means, charging means, developing means, transfer device,
This is a structure in which image forming process means such as a static eliminator and a cleaning device are arranged.

The photosensitive drum 10, which is an image forming body, is formed by forming a photosensitive layer such as an a-Si layer or an organic photosensitive layer (OPC) on the outer periphery of a substrate such as a cylindrical aluminum substrate. That is, the base and the conductive layer are rotated in the clockwise direction shown by the arrow in FIG.

The scorotron charger 11, which is a charging means, is used in the image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and the above-described organic photosensitive member of the photosensitive drum 10 is used. The body layer is charged by a control grid held at a predetermined potential and a corona discharge by a discharge wire to give a uniform potential to the photoconductor drum 10.

The exposure unit 12 as an image exposing means for each color has an FL (phosphor emission), an EL (electroluminescence), and a PL (plasma discharge) arranged in the main scanning direction in parallel with the axis of the photosensitive drum 10. , A linear exposure element in which a plurality of light emitting elements such as LEDs (light emitting diodes) are arranged in an array, and a SELFOC lens as an equal-magnification imaging element are configured as an integrated unit. Exposure unit 12 provided in a state of including 10
The image signal of each color stored in the memory is sequentially read from the memory and is input to the exposure unit 12 for each color as an electric signal. The emission wavelength of the light emitting device used in this embodiment is 780 to 90, which has high transmittance of Y, M, and C toners.
It is in the range of 0 nm.

The developing device 13, which is a developing means for each color, contains one-component or two-component developers of yellow (Y), magenta (M), cyan (C) and black (K), respectively, and is exposed to light. The developing sleeve 13a is provided which rotates in the same direction while maintaining a predetermined gap with respect to the peripheral surface of the body drum 10.

The developing device 13 for each of the colors described above applies 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 unit 12 described above. Reverse development is performed in a non-contact state by a non-contact developing method.

As the original image, an image read by an image pickup device of an image reading apparatus separate from this apparatus or an image edited by a computer is temporarily stored as an image signal for each color of Y, M, C and K. Store and store in.

When image recording is started, a photoconductor drive motor (not shown) is rotated to rotate the photoconductor drum 10 in the clockwise direction shown by the arrow in FIG. The charging action of the scorotron charger 11 starts to apply a potential to the photoconductor drum 10.

After a potential is applied to the photoconductor drum 10, exposure is started by an electric signal corresponding to the first color signal, that is, the Y image signal in the Y exposure unit 12, and the surface of the photoconductor drum 10 is exposed by rotation scanning of the drum. An electrostatic latent image corresponding to the Y image of the original image is formed on the layer.

The latent image is reversal-developed by the Y developing device 13 with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Then, the photosensitive drum 10 is charged on the yellow (Y) toner image and further by a charging action of a magenta (M) scorotron charger 11 arranged on the left side of the photosensitive drum 10 and above Y. Exposure is performed by an electric signal corresponding to the second color signal of the M exposure unit 12, that is, the image signal of M, and the yellow (Y) color is developed by non-contact reversal development by the developing unit 13 of M. A magenta (M) toner image is sequentially superposed on the toner image.

A cyan (C) scorotron charger 1 disposed above the photosensitive drum 10 by the same process.
The cyan (C) toner image corresponding to the third color signal is further generated by the exposure units 12 of 1 and C and the developing device 13 of C, and the black (K) color image is disposed below the C on the right side of the photosensitive drum 10. ) Scorotron charger 11 and exposure unit 1
2 and the developing device 13 sequentially form a black (K) toner image corresponding to the fourth color signal, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation. It

The developing device 13 for each color and the photoconductor drum 10 have a predetermined value, for example, 100 .mu.
m-1000 μm and kept in non-contact with each other, and when the developing device 13 performs the developing operation, the developing sleeve 13a
To the photosensitive drum 10 having a transparent conductive layer grounded, a developing bias with a direct current or an alternating current applied thereto is applied to perform a jumping development with a one-component or two-component developer accommodated in the developing device. A non-contact reversal development for applying toner to the exposed portion is performed by applying a DC bias of the same polarity.

A transfer sheet P, which is a transfer material, is sent out from a paper feed cassette 15 which is a transfer material storage means, and is conveyed to a timing roller 16. The color toner image formed on the peripheral surface of the photoconductor drum 10 is transferred to the photoconductor drum 10 by driving the timing roller 16 in the transfer device 14a.
It is transferred onto a transfer paper P which is a transfer material that is fed in synchronization with the above toner image.

The transfer paper P on which the toner image has been transferred is discharged from the drum peripheral surface in the static eliminator 14b and separated from the peripheral surface of the drum, and is then conveyed to the fixing device 17 by the conveyance belt 14e which is a conveying means. After the toner is welded and fixed on the transfer paper P by being heated and pressure-bonded in the fixing device 17, the toner is discharged from the fixing device 17 and is conveyed by the pair of paper discharging / conveying rollers 18 a, and is discharged onto the tray on the upper part of the device through the paper discharging rollers 18. The toner image surface is discharged to the bottom.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
Is rubbed against the surface of the photoconductor drum 10 by the cleaning blade 19a in the cleaning device 19 to remove and clean the residual toner and continue to form the toner image of the original image, or temporarily stop the toner image of a new original image. Formation. The waste toner scraped off by the cleaning blade 19a and the cleaning roller 19b is discharged to a waste toner container (not shown) through the toner carrying screw 19c and the toner carrying pipe 19d. After cleaning, the cleaning blade 19a
The cleaning roller 19b and the cleaning roller 19b are kept apart from the photosensitive drum 10 in order to prevent damage to the photosensitive drum 10.

The main structure of the color image forming apparatus will be described with reference to FIGS. 2 is a cross-sectional view of an essential part of FIG. 1, FIG. 3 is a side cross-sectional view taken along the line AA of FIG. 2, and FIG. 4 is a schematic view of a support member.

The exposure unit 12 for each color is attached to the exposure unit attachment hole 51 of the cylindrical support member 50, and the cylindrical support member 50 to which the exposure unit 12 for each color is attached is the main body of the color image forming apparatus. Front side plate 4
Side plate 4 on the rear side of the apparatus body
1 is connected to the pin 55 provided on the support member 50 and the hole 55b of the ear portion 55a of the rear flange 55 provided on the support member 50, and the support member 50 is positioned with respect to the apparatus body. The ears 54a of the provided front flange 54 are screwed through the holes 54b of the ears 54a to the side plate 40 on the front side by screws 57, and the support member 50 is fixed.

A photosensitive drum 10 as a cylindrical image forming body in which the front flange 10a and the rear flange 10b are integrated.
Is inserted into the support shaft 30 of the image forming body, is fixed to the support shaft 30 by the fixing pin 10c, and the side surface of the rear portion of the support member 50 in a state where the photosensitive drum 10 is enclosed in the cylindrical support member 50. A rear end 30b of the support shaft 30 is fitted into a bearing 57, which serves as a bearing provided at the center of the cylindrical support member 50 at 56. An E-ring 32 for retaining is fitted in the rear end portion 30b, and the gear G1 is further fixed by a fixing pin 33. Since the image forming body and the image exposing means are mounted in a state where the center positions are concentrically aligned with each other by the bearing, the gap between the image exposing means and the image forming body and the distance between the image exposing means and the image forming means are accurately aligned. Kept in.

Guide groove 152 provided in the support member 50
The guide rails 111a and 111b are fitted into the a and 152b, and the scorotron charger 11 for each color is attached to the support member 50. Further, the guide pins 119a, 1a are attached to the left and right guide rails 151a, 151b provided on the support member 50.
The cleaning device 19 is attached to the support member 50 by inserting 19b.

The disk-shaped support member 60 is the support member 50.
Of the support member 50 and the support member 6 on the reference pin 54c for positioning the support member provided on the front flange 54 of the
0 is positioned and fitted, and the support member 60 allows the support member 60 to move the photosensitive drum 10 to the front end portion 30a of the support shaft 30 of the image forming body by a bearing 61 provided at the center position of the disk-shaped support member 60. It is inserted with the shaft supported.
The support member 60 is fixed to the support member 50 by the screw 62. A retaining E ring 31 is fitted on the support shaft 30. Since the image forming body and the image exposing means are mounted in a state where the center positions are concentrically aligned with each other by the reference pin, the alignment between the image exposing means and the image forming body and the distance between the image exposing means and the image forming means is high. Maintained in precision.

A gear G1 provided on the photosensitive drum 10 is connected to a gear G2 connected to a drive motor (not shown) provided on the main body of the apparatus, and an exposure unit 12 as an image exposure means is provided.
In the state in which the alignment between the gap between the photosensitive drum 10 as an image forming member and the exposure unit 12 for each color with respect to the photosensitive drum 10 is maintained with high accuracy, the photosensitive drum 10
Can be rotated.

Further, the developing device 13 is fixed in a hole 52 for mounting the developing device, which is provided in the support member 50, in a state of not being in contact with the photosensitive drum 10. Further, the transfer device 14a and the static eliminator 14 are provided in the cutout holes 53 provided in the support member 50.
b and the transport belt 14e are fixed to the apparatus main body without contact with the photosensitive drum 10.

At the time of maintenance and replacement of the photoconductor drum 10 as an image forming body, the screw 62 and the E ring 31 are removed, and the support member 60 is removed from the support shaft 30 of the photoconductor drum. The drum 10 is replaced and removed.

[0034]

According to the first or second aspect of the present invention, when the image forming body is exchanged, the center position between the image forming body and the image exposing means is not displaced, and the image forming body and the image exposing means form an image. Mutual gaps are maintained with high precision without misalignment, and image formation without blurring is achieved. Further, when the image forming body is exchanged, the center position between the image forming body and the image exposing means is not displaced, and there is no misalignment in the alignment of the distance between the image exposing means with respect to the image forming body, and a color image having no color deviation is obtained. It is formed.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of a main part of FIG.

FIG. 3 is a side sectional view taken along line AOA of FIG.

FIG. 4 is a schematic view of a support member.

[Explanation of symbols]

10 Photosensitive drum 12 Exposure unit 30 support shaft 50 Support member 54c Reference pin 57,61 bearings 60 Support member

Claims (2)

(57) [Claims] 1. A cylindrical image forming body for forming a latent image, a charging unit for charging the image forming body around the image forming body, and a latent image formed by exposing the charged image forming body to an image. A plurality of sets of image exposure means for forming a toner image and developing means for developing a latent image formed on the image forming body to form a toner image are arranged, and the image forming body is rotated during one rotation of the image forming body. On the other hand, a plurality of toner images are superposed on the image forming body by sequentially repeating the formation of the toner image by the charging by the charging means, the image exposure by the image exposing means, and the development by the developing means. In a color image forming apparatus for collectively transferring toner images onto a transfer material, a cylindrical support for supporting the image exposing unit concentrically with the image forming body so as to surround the outside of the cylindrical image forming body. A circle is provided on the side surface of the support member. A color image forming apparatus comprising a support shaft bearing for supporting the image forming body at a cylindrical center position. 2. The color image according to claim 1, wherein a support member for supporting the support shaft is provided, and the support member is coupled to a reference pin for positioning provided on the support member. Forming equipment.