JPH034242A - Image forming device using amorphous silicon photosensitive body - Google Patents

Abstract

PURPOSE:To shorten the first copying time by rotating the photosensitive body less than one revolution before latent image formation in the first copying, and controlling a paper feed time so that a part having an image through prexposure coincides with the leading edge of a transfer paper, in the image forming device using the amorphous Si photosensitive body. CONSTITUTION:Electrostatic latent images are formed on a photosensitive body surface in sequence by uniformly electrifying the photosensitive body to a prescribed potential by means of a corona-electrifier 3 and by exposing it. A developing device 6 carries out toner development, and an electrifier 7 discharges corona to improve separation. Each transfer paper set in cassettes 8 and 9 and a deck 10 reaches a roller 14 by means of rollers 11, 12, and 13, respectively. The roller 14 is driven so as to match the time that the point E of a photosensitive surface reaches a point F after an exposure device 2 is lit, therefore the leading edge of the transfer paper reaches the point F. After that, transfer fixing and ejection of the paper, on which an image is formed, are carried out. The roller 14 is controlled only in first copying or in a single mode copying. Since the amorphous Si photosensitive body is used, previous history is eliminated during stop, and does not affect the subsequent copying; the time first copying requires can be shortened because the photosensitive body has less than one prerotation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrophotographic apparatus using an amorphous silicon photoreceptor.

[Prior Art] Conventionally, electrophotographic photoreceptors include vapor deposition systems such as a-Se,
Inorganic pigment dispersion systems, in which inorganic pigments such as CdS and ZnO are dispersed in resin, and organic photoreceptors (OPC), in which organic content/dye is formed into a resin film, have been widely used.

When these photoconductors are used in an electrophotographic device, a cleaning blade that is separated from the photoconductor is brought into contact with the photoconductor to protect the surface of the photoconductor, and optical memory and charged memory formed during paper feeding are removed. In order to remove electrostatic defects such as ) was used.

On the other hand, in one copy (or print), the photoreceptor undergoes processes such as charging, exposure, development, transfer, separation, and cleaning, and is therefore subjected to impact by the developer and friction by the cleaning member. Therefore, as the number of rotations of the photoreceptor increases, the time during which the photoreceptor is exposed to these influences also increases, and the possibility of encountering troubles such as abnormal discharge and contamination with foreign matter also increases. That is, the rotation speed of the photoreceptor is an important factor that influences the life of the photoreceptor.

Currently, one or more pre-rotations are performed at the start of copying. With a high-speed 50 sheets/min machine, the average volume of one continuous copy (hereinafter referred to as the average continuous copy volume) is about 3 copies, and the required time is 6 to 7 seconds, but it occupies more than 1 second of that time. The pre-rotation required is about 15% of the total number of rotations, which affects the life of the photoreceptor. In other words, pre-rotation is indispensable in an electrophotographic apparatus using such a photoreceptor, and the number of rotations for this purpose is 1.
2% increase (equivalent to 15% decrease in service life), and 10 sheets/mi
For low-speed machines below n, the average continuous copy volume is as small as about 1, so the ratio of the previous rotation speed to the total rotation speed is over 40%, increasing the rotation speed by 17% (with a 40% reduction in service life). 6 In particular, for low-speed machines, the average continuous copy volume is small, so as mentioned above, the pre-rotation ratio is large, and the copy speed is slow, so the pre-rotation time is about 4 There was a drawback that the time required for the first copy was nearly 15 seconds.

[Problems to be Solved by the Invention] In order to solve these problems, it is possible to eliminate the pre-rotation, which used to require more than one rotation in the electrophotographic process, or to reduce it to less than one rotation. By taking such measures, an image forming apparatus that has multiple paper feeding units corresponding to the paper size specification, especially an image forming apparatus that has a paper deck for large-volume copying in the lower tier, allows the upper tier, middle tier, The length of the paper feeding path differs in the lower stage. For this reason, the timing at which the transfer paper reaches the developing section of the photoreceptor is different, and the paper feed path is shorter than that of the lower paper deck, which has a longer paper feed path, and the leading edge of the transfer paper fed from the middle cassette is , the developing part of the photoreceptor that has only been charged without pre-exposure is reached, and density unevenness occurs between images from the parts that have been charged after pre-exposure. There was a drawback.

An object of the present invention is to form an image in which the paper feeding timing can be controlled so that the portion where the image is formed by charging after pre-exposure is the same at the leading edge of the transfer paper fed through each paper feeding path. The goal is to provide equipment.

[Means for Solving the Problems] The present invention, which can solve the above problems, is an amorphous paper that has a plurality of paper feeding paths of different lengths and that repeats pre-exposure, charging, image exposure, development, transfer, separation, and cleaning. In an image forming apparatus using a silicon photoreceptor, the rotation of the photoreceptor before forming a latent image during first copying is kept to less than one rotation, and the area where the image is formed after pre-exposure is almost the same as the leading edge of the transfer paper. This image forming apparatus is characterized in that it is provided with a control means for controlling the paper feeding timing so that the paper feeding timing is controlled.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of an image forming apparatus that best represents the features of the present invention, in which 1 is an amorphous silicon photoreceptor, 2 is a
3 is a pre-exposure device using an LED array, 3 is a corona charger,
4 is a blank exposure device for eliminating electricity from non-latent image areas, 5 is an image exposure device for forming a latent image, 6 is a developing device, 7 is a pre-transfer charger, 8 is an upper paper feed cassette, 9 is a middle paper feed cassette , I
O is the lower paper deck, 11.12.13 is the upper, middle,
A paper feed roller for the lower paper feed cassette or paper deck; 14 indicates a registration roller which is a control means for conveying the fed transfer paper at an appropriate timing; 15 is a transfer charger; 16 is a separation charger, 17
18 is a conveyor belt, and 18 is a cleaner.

To form an image using this device, the corona charger 3
The photoconductor 1 is uniformly charged to a predetermined positive or negative potential by the 1-electrode 1, and then image exposure (slit exposure, laser beam scanning exposure) is performed by an exposure device (not shown), thereby forming an exposed image on the surface of the photoconductor. Electrostatic latent images are formed one after another.

Next, the developing device 6 develops the electrostatic latent image with toner, and the pre-transfer charger 7 performs corona discharge to improve separation. The transfer paper set in the paper feed cassette 8.9 and the paper deck 10 is transferred to the respective paper feed rollers 11, 12, .
13, the paper passes through paper feeding paths A, B, and C and reaches registration rollers 14.

Here, an operating signal is sent to the drive motor of the registration roller so that the rotational speed of the registration roller corresponds to the time from when the pre-exposure device 2 is turned on until point E reaches point F on the photoreceptor surface. , the leading edge of the transfer paper reaches point F of the photoreceptor.

Thereafter, a transfer charger 15 transfers the toner image on the photoreceptor surface to a transfer paper, and a separation charger 16 separates the transfer paper from the photoreceptor. The separated transfer paper is introduced into an image fixing device (not shown) by a conveyor belt 17, and after the image is fixed thereon, it is discharged from the apparatus as an image forming paper.

After the image has been transferred, the photoreceptor is cleaned by removing residual toner and the like by a cleaner 18, and the above steps can be repeated.

In the apparatus of the present invention, the registration rollers are controlled only when copying the first sheet or when copying in single mode.

In the device of the present invention, in order to make the pre-rotation less than one rotation, it is essential that the response of the photoreceptor is good. There is no fluctuation in the potential (i.e., the charged memory is small), the decay of the surface potential is large (usually fast for materials with a large amount of thermal free carriers), and the memory (particularly for optical memories, the trapped carriers are released). A small photoreceptor with a small optical memory is required. For this reason,
Photoconductive amorphous silicon semiconductor with high mobility1
In the present invention, in which an electrophotographic photoreceptor used in the present invention is effective, a photoreceptor having a barrier layer provided on an amorphous silicon layer is particularly preferably used. The thickness of the barrier layer is preferably about 0,005 microns to about 1.0 microns, and the thickness of the amorphous silicon layer is arbitrarily selected from the range of about 5 microns to about 100 microns.

The use of an amorphous silicon photoreceptor in the present invention is advantageous because the history of the previous image formation (electrostatic defects in optical memory, charging memory, etc.) is canceled during rest and does not affect the next latent image. can be made less than one rotation.

[Example 1 Hereinafter, the present invention will be explained according to examples.

In an image forming apparatus using an amorphous silicon photoreceptor (hereinafter referred to as a drum) shown in Figure 1, image formation is performed in single mode without previous rotation, and image formation is performed from the upper and middle cassettes or the lower paper deck. Transfer paper was fed.

At this time, the pre-exposure unit 2 is turned on, and then the E on the drum surface is The point is F
Registration roller 1 according to the time it takes to reach the point.
The rotation of the registration rollers was controlled by a ROM (not shown) programmed to operate No. 1. As a result, both the transfer paper that passed through the paper feed path C and the transfer paper that passed through the paper feed path A produced high-quality images with even density unevenness compared to the first sheet.

The image was formed on the transfer paper by adjusting the timing to match the length of the paper feed path C without controlling the registration rollers as in Example 1. As a result, the leading edge of the transfer paper that has passed through paper feed paths A and B, which are shorter than paper feed path C, passes through the registration rollers at an earlier timing than the transfer paper that has passed through paper feed path C, and is not pre-exposed. The image was transferred in contact with point D. For this reason, unevenness occurred in the image density (particularly a halftone image) at the leading edge of the transfer paper that was in contact with the drum surface from point D to point E, and a good image could not be obtained.

[Effect of the Invention 1] As explained above, according to the present invention, the feeding speed of the transfer paper is controlled by the registration roller so that the leading edge of the transfer paper is almost the same as the latent image after the pre-exposure irradiation and the leading edge of the developing section. It has become possible to make the pre-rotation less than one rotation, which shortens the time required for first copying, and it has become possible to obtain a better image than the first one no matter which cassette is specified.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the apparatus of the present invention. 1. Amorphous silicon photoreceptor 2. Pre-exposure device 3. Corona charger 4.
・Blank exposure device 5... Image exposure 6... Developer device
7... Pre-transfer charger 8... Upper paper feed cassette 9... Middle paper feed cassette 0... Lower paper deck 1512.13... Paper feed roller 4... Registration roller

Claims (1)

[Claims] In an image forming apparatus using an amorphous silicon photoreceptor that has multiple paper feed paths of different lengths and undergoes repeated pre-exposure, charging, image exposure, development, transfer, separation, and cleaning, the The present invention is characterized in that a control means is provided for controlling the paper feeding timing so that the rotation of the photoreceptor carried out during the process is kept to less than one revolution, and the area where the image is formed through pre-exposure is almost the same as the leading edge of the transfer paper. Image forming device.