JPS59206846A - Multiple copying method - Google Patents

Abstract

PURPOSE:To rapidly form good copies in succession by electrostatically charging a photosensitive body to a polarity same as the polarity to which said body is sensitive, imagewise exposing it to form an electrostatic latent image, then, uniformly charging it to the reverse polarity to reverse the image, and repeating at least development and fixation of this reversed image. CONSTITUTION:Potential Vi1 on the light areas and potential Vo1 on the dark areas are reversed to Vi2, Vo2, respectively, by charging a photosensitive drum 1 with a reversely charging corona charger 4 to a polarity reverse to a main corona charger 2, i.e., the polarity to which the drum 1 has substantially no or considerably low sensitivity, that is, reversely charging it. The reversed electrostatic latent image is developed with the following developing device 5 from a positive latent image to a normal developed image, and from a negative latent image to a reversal image. The developed image is transferred to a transfer paper 7 with a transfer roller 6, and the image transferred paper 7 is separated from the drum 1 with an AC separation charger 8. When multiple successive copying is executed, this reversed electrostatic latent image is repeatedly used.

Description

[Detailed description of the invention] Technical field 11 This invention relates to a multi-copying method using a body.

A typical example of a method for continuously copying multiple sheets is to expose the same original each time it is copied to form an electrostatic latent image, and then develop and transfer this latent image each time to make the desired number of sheets. A copy is to be obtained. However, this method has the disadvantage that it is not possible to increase the copying speed because it is necessary to perform image exposure for each copy.

From this, the electrostatic latent image formed when copying the first sheet is repeatedly used, and from the second sheet onward, the process of development and transfer (further cleaning if necessary) is repeated without exposing the image to obtain the desired number of copies. Multiple copying methods have been proposed. This method has the drawback that either the copying speed is high or the potential of the electrostatic latent image gradually decreases, resulting in a deterioration in image quality as the number of continuous copies increases. For this reason, usable photoreceptors are quite specific, and a special one called a screen photoreceptor is generally used.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned facts, and its objectives are (1) to enable the use of existing photoreceptors, to provide a simple and quick copying image in terms of structure and control; It is an object of the present invention to provide a method for making multiple copies that can be made continuously.

The gist of the present invention is to use a photoreceptor that is sensitive only to either polarity, or whose sensitivity to one polarity is sufficiently higher than the other polarity. The electrostatic latent image is charged to the same polarity as the one that is sensitive to the body, and the image is fogged to form an electrostatic latent image. Repeat at least development,
It is a multi-sheet copying method that performs transfer.

Embodiment FIG. 1 shows a schematic configuration of a copying machine in which the multi-sheet copying method according to the present invention can be carried out. A photoreceptor of this type has a photoreceptor with a thickness of 10 to 100 microns on a conductive substrate. , 62Sea is coated with a photoconductive layer, and has virtually no sensitivity to negative polarity, high sensitivity to positive polarity, and extremely higher charge retention to negative polarity than to positive polarity.

(2) The main corona charger is the photosensitive drum (1)
This is to uniformly charge the drum to the same polarity as its own sensitivity polarity, and to positively charge the drum having the As25ea light guide tFj. (3) In the image exposure section, a positive image or a negative image is sequentially projected to form an electrostatic latent image on the photosensitive drum. Note that a laser, an OF1'' for the LD, etc. may be used for image exposure.

(4) is a reversely charged corona charger, which has a polarity opposite to that of the main corona charger (2), that is, the photoreceptor drum (
1) applies a polar charge with no real sensitivity and inverts the electrostatic latent image as described later.

(5) is a developing device which develops the inverted electrostatic latent image by, for example, a magnetic brush developing method. Here, if the reversal latent image is a positive latent image, normal development is performed, and if it is a negative latent image, reversal development is performed. (6) is a transfer roller for transferring the developed image to a transfer paper (force), and (8) is a separation corona charger for peeling the transfer paper from the photosensitive drum (1), such as an AC charger. .

Further, (9) is a cleaner such as a fur brush or an elastic blade for removing toner remaining on the photosensitive drum (1), and (1o) is an optical eraser for erasing residual charges.

The multi-sheet copying method of the present invention using the copier with the above configuration will be explained based on FIG. 2. The figure shows the photosensitive drum (1).
This figure shows the surface potential patterns of the dark and bright areas (image area, non-image area) of the electrostatic latent image formed on the surface. In the first step of copying, the photosensitive drum (1) is uniformly heated by the main corona charger (2) so that it has a predetermined surface potential (Vo 1) of the same polarity as the one with which the drum itself has high sensitivity, in this case positive polarity. This is a charging process. The second step (b) is a step of sequentially projecting the image to be copied through the image exposure section (3) to form an electrostatic latent image, whereby the potential of the dark area is attenuated to a potential of 5 -. do. As described above, either a negative image or a positive image may be exposed in the second step.

The third step (C1 is a step in which the electrostatic latent image formed in the second step is reversed by a reversely charged corona charger (4). Specifically, it is opposite to the main corona charger (2) in the first step (al). In the process of charging to the same polarity as the polarity, that is, the photoreceptor itself has virtually no sensitivity or has very low sensitivity.
In FIG. 2, by nine-polarity charging, the potential of the bright part is reversed from (Vil) to (Viz), and the potential of the dark part is reversed from (VO1) to (VO2), respectively, to a negative potential. However, if the electrostatic latent image formed in the second step (BL) is a positive latent image, it is reversed to a negative latent image, and conversely, if it is a negative latent image, it is reversed to a positive latent image. The latent image has excellent charge retention and is retained for a long time because the photoreceptor used has no or low sensitivity to the potential that constitutes the latent image.In other words, charge injection occurs into the photoconductive layer. Even when exposed to light, there is almost no attenuation.

6- The reversal electrostatic latent image is developed by the developing device (5) in the subsequent fourth step (CI), or regular development is performed for a positive latent image, and reversal development is performed for a negative latent image.

At this time, a bias pressure somewhat higher than the dark potential (VO2) is applied to the developing electrode, and good development without background 17j is performed.

The fifth king (e+) transfers the image developed in this way to a transfer roller (
This is the step of transferring the image to the transfer paper (7) by step 6). This transfer roller (6) is made of a +# conductor and is used to transfer a toner image by applying a bias voltage having a polarity opposite to that of the toner. Step 6] Step 2 tt+ is a step in which the transferred transfer paper (7) is separated from the photoreceptor drum (1) by the AC separation charger (8). ,-#
Since the inverted electrostatic latent image is charged through the intervening process, the inverted electrostatic latent image is not disturbed. The separated transfer paper (7) is then fixed by a fixing means (not shown) to become the first copy. on the other hand,
Residual toner is removed from the photosensitive drum (1) by a cleaner (9) in the seventh stage (tg). Next, the photoreceptor drum (
]) follows the optical optical eraser 10), but it is preferable that it is inactive after the formation of the electrostatic latent image and until the completion of copying a desired number of sheets. However, if the drum has no substantial sensitivity to the polarity of the potential constituting the inverted electrostatic latent image, the latent image will not be destroyed in any way even if the drum is irradiated with the eraser (10).

Next, in the present invention, when a large number of sheets are to be continuously copied, the above-mentioned inverted electrostatic latent image is repeatedly used. In other words, the above 1st to 7th
After completing steps (a-g), only the fourth to seventh steps (d-g) are repeated to copy the desired number of sheets. This is shown as the second sheet in 2M, and as mentioned above, the photoreceptor drum (1) has no real sensitivity to the polarity of the inverted electrostatic latent image formed on it, so .

It has excellent load retention and will not break down over a long period of time. The inverted electrostatic latent image thus formed on the first copy is repeatedly used by repeating only the fourth to seventh steps for the desired number of copies. When the desired number of continuous copies have been completed, the photosensitive drum (1) is then charged by the main corona charger (2) (step (1) in Figure 2), and the inverted electrostatic 4 latent image is neutralized. Light eraser (10)
The remaining charges are completely erased and the multi-sheet copying operation is completed.

In the above explanation, the photoreceptor drum (1) is A,
2Se3 Not limited to those with one photoconductive layer stacked, Se
In short, any photoreceptor can be used as long as it exhibits a characteristic of being sensitive only to either positive or negative polarity or having sensitivity considerably lower than the other polarity. Also, instead of the transfer roller (6), a pressure transfer roller or 1
A normal DC corona charger may be used as long as it does not destroy the inverted electrostatic latent image. Furthermore, the AC portion i1j+charger (8) may also be used as a means for eliminating residual charges. That is, after the final copy! The latent image is neutralized by applying AC to the photoluminescent drum (1). At this time, the optical eraser (10) is not particularly required. In addition, separate charger (
Of course, separating claws, dividing tape, etc. may be used instead of 8).

Further, when a transfer roller or a pressure transfer roller is used in the transfer step, the separation means can be omitted depending on the diameter and material of the roller. Furthermore, the cleaning in the seventh step does not need to be carried out all the time, and may be carried out only when the final copy is completed.

As is clear from the explanation in ``Effects'' 2, according to the multi-sheet copying method according to the present invention, existing photoreceptors can be used and multiple copies can be made continuously and quickly from a single electrostatic image. be able to. Moreover, since the image quality of the electrostatic image does not deteriorate over a long period of time, good copying can be performed, and it has many advantages, such as being simple in terms of structure and control.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a copying machine capable of carrying out the multi-sheet copying method according to the present invention, and FIG. 2 is a diagram showing potential patterns in the copying method according to the present invention. (1)...Photosensitive drum, (2)...Main corona charger, (4)...Reverse charging corona charger. Applicant: Minolta Camera Co., Ltd. 10-! My mouth

Claims (1)

[Claims] (1) Using a photoconductor that is sensitive only to either positive or negative polarity, or whose sensitivity to one polarity is sufficiently higher than the other polarity, and the photoconductor itself has high sensitivity. A first step of uniformly charging the same polarity as the one having the same polarity, a second step of forming an electrostatic latent image by flashing the image three times, and a first step of
A third step of reversing the electrostatic latent image by charging it with a polarity opposite to that of the step, a fourth step of developing the reversed electrostatic latent image, and transferring the developed image to transfer paper. A multi-sheet copying method comprising a fifth step and a sixth step of separating the transfer paper from the photoreceptor, and repeating the fourth to sixth steps when multiple sheets are to be copied.