JPS6137627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention performs a multi-sheet copying operation in which a plurality of identical electrostatic latent images are formed on a photoreceptor and the development and transfer of these electrostatic latent images are repeated to obtain a large number of copies. Relating to a copying device.

For this type of copying machine, for example, the length of the original to be copied in large numbers is 1/2 the length of the maximum size original.
In the following cases, a plurality of electrostatic latent images are formed on the photoreceptor by the original, and the electrostatic latent images are repeatedly developed and transferred to transfer paper to obtain the desired number of copies, and then the photoreceptor is removed. Methods have been proposed for cleaning and copying at extremely high speeds. However, in such copying devices, the operation sequence of each device is generally synchronized with the rotation of the photoreceptor, so that the development and transfer of the plurality of electrostatic latent images formed on the photoreceptor cannot be carried out as desired. If the photoreceptor is cleaned after repeating the number of times depending on the number of sheets, and therefore the number of electrostatic latent images is even and the desired number of copies is odd, or the number of electrostatic latent images is odd and the desired number of copies is even. In this case, the electrostatic latent image is developed and transferred an odd number of times, and the transfer paper is fed only for the desired number of copies.
Transfer paper is not fed for this extra transfer.
For this reason, transfer members such as rollers and belts that are in pressure contact with the photoreceptor may develop an excess electrostatic latent image and transfer the toner image from the photoreceptor due to paperless transfer, causing an offset. Toner is wasted and the burden on the cleaning device for removing residual toner on the photoreceptor increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a copying apparatus which eliminates the above-mentioned drawbacks and eliminates unnecessary development and transfer of electrostatic latent images.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, an original is placed on the original table 1, the number of copies of the original is set on the preset counter 2, and the size of the original is set on the original size setting device 3. Set. The arithmetic circuit 4 determines the electrostatic potential to be formed on the photoreceptor 5 according to the number of copies and the size of the original using a signal from the preset counter 2 that corresponds to the number of sheets to be set and a signal from the original size setting device 3 that corresponds to the original size. Calculate the number of images. Then, the first control device 6 controls each device in the electrophotographic copying apparatus to perform the next operation based on signals from the preset counter 2, document size setting device 3, arithmetic circuit 4, print switch, etc.

First, the length of the original is the maximum size of the original.
When the length of the document is larger than 1/2, or when the length of the original is less than 1/2 of the maximum size and the number of copies is small, when the print switch is pressed, the photoreceptor 5 is rotated in the direction of the arrow shown in the figure. The circumferential length of the photoreceptor 5 is set to be approximately equal to the length of the maximum size document, and although it is formed in the shape of a drum, it may also be formed in the shape of a belt or the like. This photoreceptor 5 is charged by a charging device 7, and an original image is exposed by an exposure device 8 to form an electrostatic latent image. The exposure device 8 is, for example, a slit exposure device consisting of an original platen 1, a lamp 9, mirrors 10 to 12, and an in-mirror lens 13. During operation, the lamp 9 is turned on to illuminate the original on the original platen 1 and the original platen. 1 or the lamp 9 and the mirrors 10 and 11 move at a predetermined speed in the direction of the arrow shown in the figure, and the original image is sequentially exposed onto the photoreceptor 5 through the mirrors 10 to 12 and the in-mirror lens 13 to form an electrostatic latent image. Ru. In this case, the original is placed on the original platen 1.
The original platen 1 or the lamp 9 and the mirror 10 are arranged with their ends aligned with the scanning start line at the right end in the figure above.
11 moves by a distance corresponding to the set size of the document size setting device 3, and at the same time the exposure of the document on the document table 1 ends, the exposure operation for the photoreceptor 5 ends. Next, the electrostatic latent image is developed on the photoreceptor 5 by a developing device 14, which uses a two-component developer using an insulating carrier or a magnetic developer with medium resistance or higher to prevent the attenuation of the electrostatic latent image. Dry development using toner is preferred. The photoreceptor is supplied by a supply device 15.
The toner image is transferred by the transfer device 26 onto the transfer paper fed by the guide members 16-21 and rollers 22-25. After transferring the toner image, this transfer paper is separated from the photoreceptor 5 by a separating device 27,
The toner is conveyed by a belt 30 that is wound around rollers 28 and 29, and after the toner is fixed by a fixing device 31, it is discharged onto a paper discharge tray 32 as a copy. A magnetic brush developing device or the like is used as the developing device 14, and a supplying device 15 sends out transfer paper of a size set in the document size setting device 3. The transfer device 26 is, for example, one in which a roller 33 presses a transfer paper against the photoreceptor 5 to transfer a toner image. The roller 33 is connected to the charging device 3 so that the surface of the roller dielectric material is in front of the transfer position in order to reduce attenuation during transfer of the electrostatic latent image and to enable the electrostatic latent image to be used many times.
4, the static electricity is removed by a corona charger 35 on the back side of a predetermined potential of the same polarity as the surface of the photoreceptor 5.
The fixing device 31 includes, for example, rollers 36 and 37 and heaters 38 and 39. On the other hand, devices for cleaning the photoreceptor 5 include a static eliminating lamp 40 and a cleaning device 4 for removing residual toner on the photoreceptor 5.
1. Static elimination lamp 42 and static elimination corona charger 4
3 is used, but it is inactive at this time. Next, after the second rotation of the photoconductor 5, the electrostatic latent image forming device consisting of the charging device 7 and the exposure device 8 becomes inactive, and the electrostatic latent image forming operation is no longer performed. A copy is obtained from the electrostatic latent image formed. That is, each time the photoreceptor 5 rotates once, the electrostatic latent image on the photoreceptor 5 is developed by the developing device 14, and the toner image on the photoreceptor 5 is transferred by the transfer device 26 onto the transfer paper from the supply device 15. . This transfer paper is separated from the photoreceptor 5 by a separating device 27, the toner is fixed by a fixing device 31, and the paper is discharged onto a paper discharge table 32. In this way, the photoreceptor 5
One electrostatic latent image is formed on the photoreceptor 5, and one copy is obtained each time the photoreceptor 5 rotates. When the static elimination lamp 40, the cleaning device 41, the static elimination lamp 42, and the static elimination corona charger 43 operate to clean the photoreceptor 5, the copying operation ends.

Also, the length of the original is 1/1 of the length of the maximum size original.
If the number of copies is 2 or less and the number of copies is large, when the print switch is pressed, the charging device 7 and the exposure device 8 are first activated.
The electrostatic latent image forming device operates intermittently at regular intervals to sequentially form the same electrostatic latent image on the photoreceptor 5 at predetermined intervals. Then, while the photoreceptor 5 rotates several times, for example, twice, the photoreceptor 5
The number of electrostatic latent images computed by the arithmetic circuit 4 are formed at regular intervals, and during this time, all devices other than the electrostatic latent image forming device are inoperative. When all the electrostatic latent images have been formed, each electrostatic latent image on the photoreceptor 5 is developed in sequence by the developing device 14, and the toner image on the photoreceptor 5 is transferred onto the transfer paper from the supply device 15 by the transfer device 26. transcribed. This transfer paper is separated from the photoreceptor 5 by a separating device 27, the toner is fixed by a fixing device 31, and the paper is discharged onto a paper discharge table 32. In this case, the supply device 15 feeds the number of transfer sheets calculated by the calculation circuit 4 to the photoreceptor 5 during one rotation of the photoreceptor 5.
It is sent to the transfer position in synchronization with each toner image above.
On the other hand, the counter 44 is disposed near the supply device 15 and is operated by the bias of the supply device 15 to count the number of copies, and the second control device 45 controls the counter 44 and the preset counter 2. Output is added, and based on the number of copies and the set number of copies, the first electrostatic latent image on the photoreceptor 5 that has finished its use, that is, the electrostatic latent image that no longer needs to be developed or transferred, is determined. When it is detected that the tip has passed through the separation device 27, the photoconductor cleaning device consisting of static elimination lamps 40, 42, cleaning device 41, and static elimination corona charger 43 is operated to remove residual toner and electrostatic potential on the photoconductor 5. The image is removed, and the electrostatic latent image to be used last, that is, the electrostatic latent image immediately before the first electrostatic latent image to be used, in the direction of rotation of the photoreceptor 5, has been developed. It is detected and the developing device 14 is made inoperable. Therefore, regardless of the number of electrostatic latent images on the photoreceptor 5 and the set number of copies, development and paperless transfer will not be performed between the end of use and removal. The copying operation ends after the number of copies reaches the set number of copies and the portion of the photoreceptor 5 where the last used electrostatic latent image is formed is cleaned by the photoreceptor cleaning device.

As described above, according to the copying apparatus according to the present invention, a plurality of identical electrostatic latent images are formed on a photoreceptor, and the development and transfer of the electrostatic latent images are repeated to obtain a large number of copies. In a device that performs a copying operation, a control device determines which of the plurality of electrostatic latent images on the photoreceptor is determined by the outputs of a preset counter for setting the number of copies of an original and a counter for counting the number of copies. First, an electrostatic latent image that is no longer needed is detected and the photoreceptor cleaning device is activated, and at the same time, it is detected that the development of the electrostatic latent image to be used last on the photoreceptor has been completed, and the developing device is activated. Therefore, no matter how many electrostatic latent images there are and the set number of copies, the electrostatic latent images will not be developed or transferred without paper after use, and therefore the developer will not be used. This saves money, reduces the burden on the cleaning device, and prevents the toner image from being transferred to the transfer member, thereby eliminating offset.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing one embodiment of the present invention, and FIG. 2 is a block diagram showing a part of the same embodiment. 2... Preset counter, 44... Counter, 45... Second control device.

Claims (1)

[Claims] 1 Form a plurality of electrostatic latent images of the same document on a photoreceptor that moves in a fixed direction, and develop the plurality of electrostatic latent images and transfer them to transfer paper to the set number of copies set in the preset counter 2. In a copying apparatus that repeatedly obtains a set number of copies according to the number of copies, there is a counter 44 for counting the number of copies, and a plurality of copies on the photoreceptor based on the outputs of this counter 44 and the preset counter 2. Detects the first unnecessary electrostatic latent image among the electrostatic latent images and operates the photoconductor cleaning device, and also detects that the development of the last electrostatic latent image to be used on the photoconductor has been completed. and a control device 45 for disabling the developing device.