JPS6127748B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying apparatus capable of obtaining multiple copies from one latent image.

Some electrophotographic copying machines have a developing device that also performs a cleaning action so that one copy is obtained every two revolutions of the photoreceptor, but they have the disadvantage that high-speed copying cannot be performed. On the other hand, an electrophotographic copying apparatus is also known that forms one electrostatic latent image on a photoreceptor and sequentially obtains a large number of copies from this electrostatic latent image each time the photoreceptor rotates, and copies at an extremely high speed. be able to. However, in such an electrophotographic copying apparatus, the photoreceptor is cleaned by a cleaning device after obtaining a large number of copies from one electrostatic latent image, so it is necessary to move the cleaning device toward and away from the photoreceptor. A mechanism is required and the configuration becomes complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic copying apparatus which eliminates the above-mentioned drawbacks, has a simple configuration, and is capable of high-speed copying.

〓〓〓〓〓
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 an original table 1, and the number P of copies of this original is set in a preset counter 2. On the other hand, the device 3 generates an output signal corresponding to the life of the electrostatic latent image formed on the photoreceptor 4, and includes, for example, a storage device that stores the number N of copies obtained from one electrostatic latent image. . The end-of-life detection device 5 receives the output of the storage device 3 and detects whether the copies are N from the same original.
Each time a sheet is obtained, it is detected and the life of the electrostatic latent image is detected. In this case, the end-of-life detection device 5 may be configured to count the number of copies using a counter, for example, and output an output every time the number of copies becomes an integral multiple of the output N of the storage device 3. It is also possible to use a timer in place of the storage device 3 and end-of-life detection device 4, set this timer at the time of formation of the electrostatic latent image, and set its operating time to the time required to obtain N copies in succession. Any other configuration may be used as long as it is possible to detect the end of the life of the electrostatic latent image. The control device 6 controls each device in the electrophotographic copying apparatus to perform the following operations based on signals from the life end detection device 5, the preset counter 2, the print switch, etc.

That is, in the multi-copy mode where 1<P<N, when the print switch is pressed, the photoreceptor 4 is rotationally driven in the direction of the arrow in the figure. Although this photoreceptor 4 is formed in the shape of a drum, it may also be formed in the shape of a belt or the like. During the first rotation, the photoreceptor 4 is charged by a charging device 7, and an exposure device 8 exposes the document to form an electrostatic latent image. The exposure device 8 includes a lamp 9, reflecting mirrors 10 to 12, and an in-mirror lens 13.
A slit exposure device consisting of
By moving in the direction of the arrow shown in the figure, the originals are sequentially exposed onto the photoreceptor 4. This exposure device 8 is
A slit exposure apparatus may also be used which performs exposure by moving the optical system without moving the . In this case, the circumferential length of the photoreceptor 4 is of course set to be approximately equal to the length of the maximum size document to be used. Next, the photoreceptor 4 is developed by a magnetic brush development/cleaning combination device 14, and the toner image is transferred by a transfer device 22 onto copy paper fed from a paper feed device 15 via guide members 16 to 19 and rollers 20, 21. Perform transcription. After the toner image is transferred to the copy paper, the toner is fixed by a fixing device 23, and the copy paper is discharged onto a paper discharge table 24 as a copy. In the magnetic brush development/cleaning combination device 14, it is better for the developer to have high resistance in view of the lifespan of the electrostatic latent image, so in the case of a two-component developer, a carrier with insulation treatment is used, and one component of the magnetic toner is used. In the case of a developer, a magnetic brush developing device using a developer having medium or higher resistance is preferred. The transfer device 22 is, for example, one in which a belt 25 presses the copy paper against the photoreceptor 4 to transfer the toner image.
The belt 25 is wound around rollers 26 to 28 and driven to rotate. Furthermore, in order to prolong the life of the electrostatic latent image on the photoreceptor 4, the belt 25 has its surface in contact with the copy paper charged to a predetermined potential of the same polarity as the surface potential of the photoreceptor 4 by a charging device 29 on the front side of the transfer position. The toner is electrically charged, and the charge is removed by a charge removing corona charger 30 on the rear side of the transfer position, and the toner is cleaned by a cleaning device 32 using a blade 31. The fixing device 23 includes rollers 33, 34 and a heater 35, but other fixing devices may be used. For example, a lamp 36 and a corona charger 37 are used as devices for neutralizing the photoreceptor 4, but they are inactive at this time.
Next, after the second rotation of the photoconductor 4, the charging device 7 and the exposure device 8 become inactive, and the operation of forming an electrostatic latent image on the photoconductor 4 is no longer performed.
A copy is obtained using the electrostatic latent image formed during the first rotation. That is, each time the photoreceptor 4 rotates once, the electrostatic latent image on the photoreceptor 4 is developed by the magnetic brush developing/cleaning combination device 14, and transferred onto copy paper from the paper feeder 15 by the transfer device 22.
The upper toner image is transferred, the toner is fixed on the copy paper by a fixing device 23, and the copy is discharged onto a paper discharge table 24 as a copy. When the number of copies obtained in this manner reaches the set number P, a static eliminator comprising a lamp 36 and a corona charger 37 is activated to eliminate static from the photoreceptor 4. The magnetic brush development/cleaning combination device 14 is switched from a developing operation state to a cleaning operation state in synchronization with the operating state of the static eliminator, and cleans the photoreceptor 4 to remove residual toner, and the toner is collected and used during development. Reused. The operation ends after this static elimination and cleaning operation is completed.

Also, in the multiple copy mode where P≧N, before the number of copies reaches N, the multiple copy mode where 1<P<N is 〓〓〓〓〓〓
However, when the number of copies reaches N, the static eliminating device consisting of the lamp 36 and the corona charger 37 is activated to eliminate static from the photoreceptor 4, and the magnetic brush developing/cleaning combination device 14 enters the cleaning operation state. The photoreceptor 4 is cleaned. Thereafter, the charging device 7 and the exposure device 8 operate to form an electrostatic latent image on the photoreceptor 4, and a copy is obtained from this electrostatic latent image in the same manner as described above. That is, the static eliminator consisting of the lamp 36 and the corona charger 37 becomes inactive, and the magnetic brush development/cleaning combination device 14 switches from the cleaning operation state to the development operation state, and the electrostatic charge is removed every time the photoreceptor 4 rotates once. The latent image is developed by a magnetic brush development/cleaning combination device 14, the toner image on the photoreceptor 4 is transferred from a paper feed device 15 to copy paper by a transfer device 22, and the toner is fixed to the copy paper by a fixing device 23. The paper is discharged onto the paper discharge tray 24 as a copy. When the number of copies obtained in this manner reaches P, a static eliminator consisting of a lamp 36 and a corona charger 37 is activated to eliminate static from the photoreceptor 4, and the magnetic brush development/cleaning combination device 14 is in the cleaning operation state. After the photoconductor 4 is cleaned by switching to , the operation ends.

In the single copy mode with P=1, when the print switch is pressed, the charging device 7 and the exposure device 8 are operated to form an electrostatic latent image on the photoreceptor 4, and the magnetic brush developing/cleaning combination device 14 is activated. This electrostatic latent image is developed, and the toner image on the photoreceptor 4 is transferred to the copy sheet from the paper feeder 15 by the transfer device 22 and fixed by the fixing device 23, and then transferred to the paper output table 2.
It is discharged at 4. Next, the photoreceptor 4 is neutralized by the static eliminating device and cleaned by the magnetic brush developing/cleaning combination device 14, after which the operation ends.

Note that the photoreceptor 4 may be cleaned two or more times.

As described above, according to the electrophotographic copying apparatus according to the present invention, the structure is simplified because the developing device also performs a cleaning action, and in the single copy mode, one copying process is performed with two or more rotations of the photoreceptor. However, in multi-copy mode, an electrostatic latent image is formed during one rotation of the photoreceptor, and the electrostatic latent image formed at one time is repeatedly developed and transferred to copy paper each time the photoreceptor rotates. Since a large number of copies are obtained by doing this, copying can be performed at high speed.

Furthermore, since a new electrostatic latent image is formed upon detecting the end of the life of the electrostatic latent image, the quality of the copied image can be stabilized.

[Brief explanation of the drawing]

FIG. 1 is a schematic side 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, 3...Storage device,
4... Photoreceptor, 5... Life end detection device, 6...
Control device, 7... Charging device, 8... Exposure device, 1
4... Developing device, 15... Paper feeding device, 22... Transfer device, 36, 37... Static elimination device. 〓〓〓〓〓

Claims (1)

[Claims] 1 Electrophotography in which an electrostatic latent image is formed by a latent image forming means on a photoconductor rotating in a fixed direction, and the electrostatic latent image on the photoconductor is developed and transferred to copy paper a number of times according to the set number of copies P. In a copying apparatus that uses a static eliminator to remove static electricity from the photoreceptor and uses a developing device to clean the photoreceptor after the use of the electrostatic latent image is completed, the number of copies obtained from one electrostatic latent image is a life end detection device for detecting the end of the life of the electrostatic latent image by detecting that the number of times of use of the electrostatic latent image on the photoreceptor has reached the above N, where P=1; In single copy mode, two of the above photoreceptors
Copying is performed once by rotation, and the developing device is in a developing operation state when the electrostatic latent image on the photoreceptor passes for the first time, and is in a cleaning operation state when the electrostatic latent image on the photoreceptor passes for the second time. In sheet copying mode, an electrostatic latent image is formed once during one rotation of the photoreceptor, and the photoreceptor develops the electrostatic latent image formed once on the photoreceptor and transfers it to copy paper. Repeatedly copying a large number of sheets each time the rotation is made, and the developing device is placed in a developing operation state continuously until the copying of P sheets is completed, and after the copying of P sheets is completed, it is brought into a cleaning operation state, and if P≧N. After the copying of N sheets is completed, the developing device is temporarily put into a cleaning operation state based on the output signal of the end-of-life detection device, and the static eliminator is operated, and the latent image forming means is operated to generate a new electrostatic latent image. 1. An electrophotographic copying apparatus comprising: a control means configured to continue copying.