JPH0442171A - Copy machine - Google Patents

Abstract

PURPOSE:To decrease the frequency of the movement of an optical system in continuous copying operation and to eliminate an adverse influence upon an image by forming a toner image on an insulating belt extended between a photosensitive drum and an extension drum. CONSTITUTION:An image forming process device arranged at the peripheral part of the photosensitive drum forms the toner image on the insulating belt 6. After the formation of this toner image, the insulating belt 6 leaves the photosensitive drum 4 and the toner image is held electrostatically on the insulating belt 6 as it is. Then the toner image formed on the insulating belt 6 is exposed by an optical system 10 and its reflected light is guided to the exposure part P1 of said image forming process device. Consequently, once the toner image is formed on the insulating belt 6, many same images based upon the toner image can be formed, so the accuracy of an optical system driving part can be relaxed when 2nd and succeeding images are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an improvement in a copying machine that forms a toner image by electrophotography and transfers the toner image onto paper to form an image.

(bl) Conventional technology Copying machines that use electrophotography form an electrostatic latent image by guiding reflected light from the original onto a charged photoconductor, and toner is electrostatically attached to this latent image. The reflected light from the document is generally obtained by placing the document on a document table made of transparent glass and moving an optical system along the document table.

(C) Problems to be Solved by the Invention As described above, during exposure processing, the optical system moves and the reflected light from the original is obtained. However, these movements cause vibrations, and these 4Jtf movements sometimes cause distortions in the formed image. For example, when making multiple copies from the same original, scanning of the next copy may start while the previous copy is being transferred, causing vibrations that may cause transfer blur. There were times when I ended up doing this. In order to suppress such vibrations, it was necessary to make quite elaborate work on the adjustment mechanism 2, which resulted in high cost.

Additionally, the entire device had to be strong enough to withstand frequent vibrations.

In particular, in high-speed copying machines, the optical system moves at a high speed, resulting in large vibrations and a more complex structure.

SUMMARY OF THE INVENTION An object of the present invention is to provide a copying machine that can reduce the number of times the optical system is moved, especially during continuous copying, thereby preventing adverse effects on images and, as a result, simplifying the apparatus. It is in.

(Means for Solving the d1 Problems) This invention includes a photosensitive drum having a photosensitive layer formed on a conductive substrate, an insulating belt stretched between a tension drum having approximately the same diameter as the photosensitive drum, an image forming process section including a charger, an exposure section, a developing device, etc., disposed around the photosensitive drum to form a toner image on the insulating belt; and an image forming process section fixedly disposed opposite the insulating belt; The present invention is characterized by comprising an optical system that exposes the toner image formed on the insulating belt and guides the reflected light to an exposure section of the image forming process section.

(e) Function In the present invention, first, a toner image is formed on an insulating belt by an image forming process device disposed around the photosensitive drum. That is, a toner image is formed on an insulating belt, which is an insulating layer, in the same manner as in the conventional image forming process using a three-layer photoreceptor in which a conductive substrate, a photosensitive layer, and an insulating layer are laminated. After the toner image is formed, the insulating belt separates from the photosensitive drum, but the toner image remains electrostatically held on the insulating belt.

The toner image formed on the insulating belt is exposed to light by an optical system, and the reflected light is guided to an exposure section of an image forming process device disposed around the photosensitive drum. That is, a toner image is formed on the insulating belt by the reflected light from the toner image. For this reason, once an l.toner image is formed on the -shifting edge belt, the same image can be formed on many sheets based on the toner image.

(f) Embodiment FIG. 1 is a schematic front view of a copying machine which is an embodiment of the present invention.

On the front side of the copying machine body, there is a document table 1 made of transparent glass.
is provided. Below the document table 1 are lights a, 2a,
A first optical system 2 (the optical system according to the present invention is a second optical system described later) including mirrors 2b to 2g and a lens 2h is provided. The first optical system 2 exposes the original placed on the original platen 1, and guides the reflected light to the exposure section P1 of the image forming process section. In this case, a photosensitive drum 4 and a tension drum 5 are provided in the center of the copying machine main body, whose optical axis is indicated by a dashed line, and a distance between the two drums 4.5 and 5 is provided.
An insulating root 6 is stretched. The photosensitive drum 4 is, for example, a conductive substrate made of aluminum or the like on which a photosensitive layer of CdS or the like is formed, and the tension drum 5 is a mirror-finished drum. Further, the base color edge belt 6 is an insulating belt made of PET (polyethylene terephthalate) or the like. Photosensitive drum 4 and tension drum 5
rotates clockwise, which causes insulating bell l-6 to rotate in the same direction.

Around the photosensitive drum 4, an image forming process comprising a first charger 41, a first lamp 42, a second charger 43, an exposure section P1, a post lamp 44, and a developing device 45 is arranged so as to face the insulating route 6. A section has been established. A toner image is formed on the insulating belt 6 by this image forming process section. Incidentally, reference numeral 46 denotes a static elimination charger that eliminates static electricity from the photosensitive drum 4. Furthermore, a transfer charger 51 , a static elimination charger 52 , and a cleaner 53 are arranged around the tension drum 5 so as to face the insulating belt 6 . A paper cassette 7 is arranged on the left side of the copying machine main body, and feeds the stored paper to the position of the transfer charger 51. A toner image is transferred onto this paper by a transfer charger 51, and after the toner image is fixed by a fixing device 8, it is discharged onto a paper discharge tray 9.

At the bottom of the copying machine body there is a light filOa and a mirror 10b~
10c, second optical system 1 including lenses 10d to 10e
0 (optical system according to the present invention) is fixedly arranged. Second
As shown in the figure, the second optical system 10 includes an insulating belt 67,
That is, the toner image formed on the insulating belt 6 is exposed, and the reflected light is guided to the exposure section P1 of the image forming process section. The mirror 2g of the first optical system is rotatable, and when the second optical system 10 is in operation, it is rotated to the position shown in FIG. 2 to guide the reflected light of the toner image to the exposure section P1.

In the copying machine configured as described above, the process of forming a toner image on the insulating belt 6 will be described first. Third
The figure is a diagram to explain the process. In the figure, 4a is a conductive substrate, 4b is a photosensitive layer, and 4c is a minute space formed between the photosensitive drum 4 and the insulating belt 6.

<First step> First, positive corona discharge is performed by the first charger 41,
A positive charge is applied onto the insulating belt 6. At the same time, weak light irradiation is performed by the first lamp 42, and the resistance value of the photosensitive layer 4b is reduced. As a result, the negative charges attracted by the positive charges on the insulating belt 6 reach the surface of the photosensitive layer, that is, the fine space 4c. FIG. 3(A) shows this state.

<Second Step> Next, the exposure portion P1 is irradiated with imaging light (original reflected light or toner image reflected light), and at the same time, the second charger 43
AC corona discharge is performed. At this time, the photosensitive layer 4
The portion (b) exposed to light (bright portion) has a reduced resistance and functions as a conductive layer, whereas the portion (dark portion) not exposed to light remains high in resistance and functions as an insulating layer. For this reason, the amount of negative charge of the AC corona is larger in the bright area than in the dark area (AC corona discharge is an alternating positive and negative corona, but the efficiency of the negative corona is high, so as a result, a negative charge is placed on the AC corona.) ), the positive charges on the insulating belt 6 caused by the first step are eliminated. Note that at this stage, the surface potential in both the bright and dark areas is zero, and there is no potential contrast. In other words, there is no electric charge in the dark area, so no potential appears. Figure 3 (B) → Figure 3 (C) 4
It shows the situation.

<3rd process> Thereafter, uniform light is emitted by the post lamp 44.

By irradiating the uniform light, the resistance value of the photosensitive layer 4b in the dark area decreases and acts on the conductor. As a result, the positive charge of Ap is attracted by the negative charge of the microscopic space 4C and moves, and the positive charge and negative charge cancel each other out. This creates a contrast in surface potential between the bright and dark areas, forming a latent image. Figure 3 (
D)→FIG. 3(E) shows this state.

<Fourth Step> Toner negatively charged by the developing device 45 is attached to the dark portion of the electrostatic latent image formed in the third step to form a toner image (FIG. 3(F)).

A toner image is formed through the steps described above. Thereafter, the toner image forming portion of the insulating belt is separated from the photosensitive drum 4, but the toner image remains electrostatically formed on the surface of the insulating belt 60 (FIG. 3(G)).

The toner image formed as described above is transferred onto the paper fed from the paper cassette 7 by the transfer charger 51, and fixed onto the paper E by the fixing device 8. Note that after the 1-toner image is transferred, the insulating belt 6 is neutralized by a static eliminating charger 52, and residual toner on the surface is removed by a cleaner 53.

Next, the processing when continuous copying processing is performed by this copying machine S will be explained.

First, the first optical system 2 guides the reflected light from the original placed on the original platen 1-A to the exposure section P1 to form a toner image on the insulating belt 6. When the exposure process from the original is completed, the mirror 2g of the first optical system is rotated, and the second optical system 10 is then activated to form the insulating belt 6 and expose the reflected light of the toner image. The image is guided to section P1 to form the next 1-ner image.

Here, when configuring the insulating belt 6, care must be taken that the distance between the position P2 where the toner image is exposed by the second optical system 10 and the exposure portion P1 is smaller than the maximum image size to be formed. This is because after the exposure process from the original is completed, the toner image needs to reach the exposure point P2 and be exposed. Based on this, the next toner image is formed and continuous image forming processing is performed.

(Effects of the invention As described above, if the next toner image is formed based on the previously formed toner image during continuous image formation, there is no need to scan the same document many times with the optical system. Alternatively, the number of times the document table needs to be moved can be reduced.Therefore, there is no need to worry about the vibration of the optical system or the document table when forming the second and subsequent images, and the accuracy of the optical system drive unit can be reduced. Furthermore, since there is less vibration, there is an advantage that the overall strength of the device can be reduced.

1st optical system, 4- Angry Light Tiger J., 5- tension drum, 6-
Insulating belt, 10-second optical system.

Claims (1)

[Claims] (1) A photosensitive drum with a photosensitive layer formed on a conductive substrate, an insulating belt stretched between the tension drums having approximately the same diameter as the photosensitive drum, and a toner image on the insulating belt. an image forming process section including a charger, an exposure section, a developing device, etc., arranged around the photosensitive drum to form toner; and an image forming process section fixedly arranged opposite to an insulating belt to form toner on the insulating belt. A copying machine comprising: an optical system that exposes an image and guides the reflected light to an exposure section of the image forming process section.