JPH08146695A - Color image forming device - Google Patents

Abstract

PURPOSE: To miniaturize a device by integrating both cleaning devices for a photoreceptor and an intermediate transfer body and to improve maintainability by using waste toner boxs in common. CONSTITUTION: An endless belt-like photoreceptor 7 supported by a pair of rollers is horizontally supported, developing tanks 3, 4, 5 and 6 having the toner of black, magenta, cyan and yellow respectively are horizontally arranged in this order from the upstream part in a rotational direction in the upper part of the photoreceptor 7 and the intermediate transfer body 11 is arranged opposite a roller in the downstream part in the rotational direction of the endless belt-like photoreceptor without contact with the surface of the photoreceptor. Further, a waste toner housing means 10 of the cleaning device for removing and housing the waste toner remaining on each of the photoreceptor and the intermediate transfer body is used in common.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to form a color image by successively superimposing images visualized on the surface of a photoconductor for each color on an intermediate transfer member, and retransferring the color image to recording paper. The present invention relates to a color image forming apparatus for obtaining a color image by means of a cleaning means for removing the residual toner on the surface of the photoconductor and the residual toner on the intermediate transfer body.

[0002]

2. Description of the Related Art A conventional color image is obtained by sequentially superimposing images visualized on the surface of a photoconductor on an intermediate transfer member to form a color image, and retransferring the color image to a recording paper. In the color image forming apparatus, the cleaning devices for removing and storing the residual toner on the surface of the photoconductor and the surface of the intermediate transfer body are individually arranged.

[0003]

However, when a cleaning device is provided for each of the photoconductor and the intermediate transfer member, a waste toner box is required for each and a means for detecting the amount of waste toner is required for each. . Also,
Since the amount of waste toner in each waste toner box rarely fills at the same time, each waste toner box must be individually replaced, which reduces work efficiency. To solve these problems, JP-A-63-292156 and JP-A-4-318886.
It has been proposed to integrate the respective cleaning devices by the method described in (1).

However, in Japanese Patent Laid-Open No. 63-292156, after the image data on the intermediate transfer member is transferred onto the transfer paper, the intermediate transfer member is cleaned, and the printing time is very long. In addition, JP-A-4-31888
In No. 6, since the waste toner on the photoconductor and the intermediate transfer member is conveyed to the storage device by the specially provided conveying means, the waste toner conveying mechanism is expensive.

[0005]

In order to solve the above problems, in the color image device of the present invention, the endless belt-shaped photoconductor and the intermediate transfer member are rotated in opposite directions, and a cleaning device for the photoconductor and the intermediate device are provided. It is characterized in that the waste toner storage means of the transfer device cleaning device is common.

[0006]

Since the cleaning device for the photosensitive member and the intermediate transfer member is integrated, the printer main body can be downsized and the cost can be reduced. Further, since the intermediate transfer member can be cleaned while transferring the image data on the intermediate transfer member to the transfer paper, the printing time can be extremely shortened.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a color image forming apparatus which is a first embodiment of the present invention. Endless belt-shaped photoreceptor 7
Is a negatively charged photoconductive belt, the surface of which is uniformly negatively charged by the corona charger 8 and rotated in the direction shown. A light irradiation device 1 using a semiconductor laser irradiates a pulsed laser 2 corresponding to image data to form an electrostatic latent image. A developing device having four color toners for forming a color image is provided in the horizontal direction above the endless belt-shaped photosensitive member 7, and the endless belt-shaped photosensitive member 7 is black from the upstream side in the rotational direction. Developing device 3, red (magenta) developing device 4, blue (cyan) developing device 5, and yellow (yellow) developing device 6 are arranged in this order facing the endless belt-shaped photoreceptor 7. Only the developing device having the color to be recorded is in pressure contact with the endless belt-shaped photoreceptor 7, and the developing devices having other colors are in contact with each other.

A transfer drum 11 whose surface is charged to a positive potential is provided downstream of the position where each developing device is provided in the rotational direction of the endless belt-shaped photosensitive member 7, and each developing device is provided. Endless belt-shaped photoreceptor 7 visualized by
The toner image on the surface is once transferred onto the transfer drum 11. On the endless belt-shaped photoreceptor 7, charging, exposure and development are performed for each color, and four colors are superposed on the transfer drum 11. On the other hand, the residual toner on the surface of the endless belt-shaped photosensitive member 7 is pressed by the inclination of about 30 ° with respect to the direction of rotation of the endless belt-shaped photosensitive member 7 while being pressed.
Is scraped off by the waste toner box 10f by the waste toner box 10f, and the surface of the endless belt-shaped photoconductor 7 after the residual toner is removed is removed by the neutralizer 9
Is discharged by. After a lapse of a certain time after the start of exposure of the final color, the paper is fed by the paper feed roller 15. When the leading edge of the sheet is conveyed to the transfer roller 12 via the conveyance roller 13, the transfer roller 12 is pressed against the transfer drum 11.
By pressing and applying a positive potential to the transfer roller 12, the toner image on the transfer drum 11 is transferred to a sheet.

Residual toner on the transfer drum 11 is removed by a brush roller 10b which is capable of coming into contact with the transfer drum 11 and charged to a positive potential. Brush roller 1
The toner adhering to 0b is transferred to the aluminum roller 10c that is charged with a positive polarity having a higher electric potential, is scraped off by the blade 10e contacting the surface thereof, and is stored in the waste toner box 10f. The opening / closing plate 10d operates so as to be opened only when the endless belt-shaped photoreceptor 7 and the transfer drum 11 are rotating, and when not operating, the waste toner box 1
It works to shield from 0f. After the transfer of the sheet, the sheet and the transfer drum 11 are electrically attracted to each other, so that a negative corona is applied from the back side of the sheet by a sheet separation corona charger (not shown) to separate the sheet from the transfer drum 11. The toner image on the paper is thermally fixed by the fixing device 14 including the heat roller 14a and the pressure roller 14b, and is discharged by the transport rollers 16 and 17 and the paper discharge roller 18.

The primary transfer process from the photosensitive member to the intermediate transfer member, which is a feature of the present invention, will be described in more detail. A conventional primary transfer process model diagram is shown in FIG. As shown in FIG. 2, the endless belt-shaped photoreceptor 7 and the transfer drum 11 are
It keeps a certain distance and separates and rotates in the same direction. The aluminum base 7b of the endless belt-shaped photoreceptor 7 is grounded, and the photoconductive portion 7
The high potential power source 19 has a dark potential of about −525V, and the light potential of the photoconductive portion 7a is about −30V to −40V because the potential of the aluminum base 7b is used as a reference potential. Therefore, the toner 21, which is charged in advance with a potential of about −250V, transfers to the bright potential portion. On the other hand, the transfer drum 11
The surface potential of the positive voltage is about +
Since it is uniformly charged to 300V, the negatively charged toner image 21 on the surface of the endless belt-shaped photoreceptor 7 is transferred onto the transfer drum 11 by the Coulomb force due to the potential difference of about 300V. Therefore, in the conventional primary transfer process, since the arrangement of the cleaning device for the transfer drum 11 rotates in the same direction as the endless belt-shaped photosensitive member 7, the transfer portion to the paper is downstream in the rotation direction of the transfer drum 11. Had to place it on the side. Therefore, the cleaning device for the photoconductor and the cleaning device for the intermediate transfer member are difficult to be integrated because they are separated from the cleaning device for the photoconductor.

Therefore, in the present invention, the above-mentioned problems are solved by the embodiment of the primary transfer process shown in FIG. In FIG. 3, the endless belt-shaped photoreceptor 7 and the transfer drum 11 are rotated in different directions to perform the primary transfer onto the transfer drum 11. The problem here is that the intermediate transfer member is reversely rotated with respect to the photosensitive member to transfer the toner, but in the present invention, the transfer is performed by increasing the electric field strength between the photosensitive member and the intermediate transfer member. We are working to improve efficiency. Although it can be easily realized by increasing the surface potential of the intermediate transfer member as a means for increasing the electric field strength, a large capacity UP of the high voltage power supply is used to improve transfer efficiency in paper transfer, resulting in an increase in cost. Connect Therefore, in this embodiment, as shown in FIG. 3, the high voltage power source 19 is connected to the aluminum base 7b, and the photoconductive portion 7a is connected.
That is, the Zener voltage is about 500V to the grid control terminal.
It is configured to be connected to the high-voltage power supply 19 via the Zener diode 22. As a result, the dark potential on the surface of the endless belt-shaped photoreceptor 7 is about -1.025 KV and the light potential is about -525.
The voltage difference can be set to V, and the potential difference between the photoconductor and the intermediate transfer member can be realized from a conventional configuration of about 300 V to about 800 V with a simple configuration.

With the above arrangement, the cleaning position of the intermediate transfer member can be brought close to the cleaning position of the photosensitive member, the cleaning device for the photosensitive member and the cleaning device for the intermediate transfer member can be integrated, and the waste toner is removed. By sharing the box, the maintainability was also improved.

[0013]

According to the present invention, by integrating the cleaning device for the photosensitive member and the cleaning device for the intermediate transfer member, the size of the device can be reduced, and the shared waste toner box improves the maintainability. .

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of an embodiment of a color image forming apparatus according to the present invention.

FIG. 2 is a side view showing a conventional example of a primary transfer process.

FIG. 3 is a side view showing a specific example of a primary transfer process used in the present invention.

[Explanation of symbols]

 3 Black Developing Device 4 Red Developing Device 5 Blue Developing Device 6 Yellow Developing Device 7 Endless Belt-Shaped Photoreceptor 10 Cleaning Box 10a Cleaning Blade 10e Cleaning Blade 10f Waste Toner Box 11 Transfer Drum

Claims (1)

[Claims] 1. A plurality of developing devices, in which endless belt-shaped photoconductors, which are rotatably driven by being supported by a pair of rollers, are arranged in a horizontal direction, and toners of different colors are provided in the upper horizontal direction from upstream in a rotational direction. An electrostatic latent image on the surface of the photoconductor is provided for each color, which has an intermediate transfer member which is arranged in a tank and faces the roller on the downstream side in the rotation direction of the endless belt-shaped photoconductor so as to be in non-contact with the surface of the photoconductor. To form a color image by sequentially superimposing the visualized image for each color on the intermediate transfer member,
In a color image forming apparatus for retransferring the color image onto recording paper, the endless belt-shaped photoconductor and the intermediate transfer member are rotated in opposite directions, and waste toner is stored in the photoconductor cleaning device and the intermediate transfer member cleaning device. A color image forming apparatus having a common means.