JPH0219446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for making multiple copies by using an image obtained by one image formation as a second original.

As one of such multiple copying methods, a method using ion modulation is known. This is a method of making multiple copies while retaining the electrostatic latent image that has been formed, but there is a limit to how much latent images can be retained, and copying multiple copies by retaining one latent image is difficult.
The limit is about 100 sheets at most. In addition, it is susceptible to the surrounding conditions of the device, requires the use of mechanically very weak parts such as a screen drum, and has the disadvantage that the structure is extremely complicated.

Another method is to transfer the toner image formed on the photoreceptor onto a web within the device to form a second original, which is then passed through a second imaging lens system to repeatedly form the image on the photoreceptor. There is something to do. This is particularly effective when making multiple copies of many different types of originals, as it allows multiple images to be formed on the web. is reduced. Furthermore, when a second lens system is used, the standards of the first original in the first lens system and the standards of the second original in the second lens system become different.
The standards for feeding transfer paper in single-sheet copying and multi-sheet copying also need to conform to these standards.

Yet another method uses a photoreceptor in which both sides of a light-transmitting conductive substrate are coated with light-transmitting photoconductive layers, toner images are formed on both sides of the photoreceptor, and the toner image on one side is As the original version of 2, there is one in which images are repeatedly formed on the other photoreceptor surface. This is an interesting idea, but a transparent photoreceptor with photoconductive layers on both sides is unrealistic, and providing developing and cleaning devices on both sides of the photoreceptor may cause contamination of the photoreceptor, and even damage to the second photoreceptor. It is difficult to obtain a clear copy as it will taint the original.

In this invention, a toner image formed on a photoconductor is transferred to a transparent body to form a second original, and this is directly projected onto the photoconductor without using a lens system to form a latent image. It is characterized in that it develops and transfers and copies a large number of sheets. The photoreceptor used in this invention is a normal photoreceptor used in general electrophotographic devices, and the device is also small, inexpensive, and has good performance.
Not only multi-sheet copying but also normal single-sheet copying is possible. Further, there is no deterioration of the second original during copying of a large number of copies, a large number of clear copies can be obtained, and the energy consumption of the apparatus is low.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved multi-sheet copying method.

A further object of the present invention is to provide the above-mentioned method which allows not only multiple copying but also single copying using a conventional photoreceptor.

A further object of the invention is to
The object of the present invention is to provide the above-mentioned method that does not cause deterioration of the original.

A further object of the invention is to provide the above method which consumes less energy.

Another object of the present invention is to provide a small, inexpensive, and high-performance multi-sheet copying apparatus using the above method.

Objects and benefits other than those described above will become apparent from the following description with reference to the drawings.

FIG. 1 is a diagram schematically showing each step in an embodiment of the method of the present invention. Each step is numbered and will be explained according to the number.
First, in step (1), the surface of the photoreceptor 1 is uniformly charged by a corona discharger 2 connected to a DC high voltage power source. This is done by moving either the photoreceptor or the corona discharger relative to each other. The charging polarity is determined by the characteristics of the photoreceptor used, but is assumed to be positive here. Next, in step (2), an optical image of the first original 3 having an image area 3a and a non-image area 3b is applied to the surface of the photoreceptor 1 using an optical system including illumination lamps 4, 5 and an imaging lens 6. Projected by. This exposure may be full surface exposure or slit exposure. As a result of this exposure, charges on the photoreceptor remain in the area corresponding to the image area 3a of the first original 3, and are erased in the area corresponding to the non-image area 3b. 1 latent image is formed.

Next, in step (3), on the surface of this photoreceptor 1,
The latent image is developed by supplying toner charged with a polarity opposite to that of the latent image, and a first toner image 7 is obtained. For development, a magnetic brush development method using a magnet 8 as shown in the figure or other development methods can be used, and the developer may be two-component or one-component, liquid or powder. The steps up to this point are no different from normal electrophotographic methods, but an image forming step in a facsimile machine or the like can be used instead.

Next, in step (4), a transparent body 9 is placed on the surface of the photoreceptor 1, and a corona discharger 10 is applied from above.
The latent image is charged with the same polarity as the latent image charge, which is stronger than that of the latent image holding the toner, and the toner image is transferred to the transparent body 9.
Transfer to. The transparent body is, for example, a polyester film with a thickness of about 100 μm. After separating the transparent body 9 from the photoreceptor surface, in step (5), the surface of the photoreceptor 1 is cleaned with a cleaning brush 11 or the like to remove residual toner on the photoreceptor surface. Next, in step (6), the surface of the photoreceptor 1 is again positively and uniformly charged by the corona discharger 2.
Then, in step (7), the transparent body 9 having the first toner image 7 is placed opposite to the surface of the photoreceptor with the toner image 7 side very close to the surface of the photoreceptor, and a relatively highly directional light beam is transmitted from above. Perform exposure. This exposure also does not matter whether it is full-surface exposure or slit exposure. Also, the gap between the transparent body 9 and the surface of the photoconductor should be as close as possible, depending on the thickness of the toner image, and should be 50 μm or less.
Approximately 200 μm is preferable. Through this step, a second latent image, which is the same as the first latent image, is formed on the surface of the photoreceptor. Next, this latent image is similarly developed in step (8) to obtain a second toner image 12. Then, in step (9), this toner image is transferred to a transfer sheet 13, which becomes a permanent transfer material, by a corona discharger 14. After separating the transfer sheet 13 from the photoreceptor surface, the photoreceptor surface is treated in step (10).
Cleaned in the same way. In the case of multiple copying, steps (6) to (10) are repeated, and in the case of single copying, steps (1), (2), (3), (9), and (10) are performed in this order. The toner image transferred onto the transfer sheet 13 is permanently fixed onto the transfer sheet by a fixing device. After copying a large number of sheets, the toner image on the transparent body 9 is removed by cleaning, and the transparent body is reused.

FIG. 2 shows an example of a copying apparatus using the above method. A transparent document table 21 is arranged horizontally on the upper surface of the apparatus main body, and on the upper surface, a flexible and opaque document holding plate 22 is arranged so as to be openable and closable with one end supported by the apparatus main body. There is. A first mirror including an illumination lamp 23 and a first reflecting mirror 24 is located inside the main body of the apparatus below the document table 21.
Reflection mirror unit 25 and second reflection mirror 2
6 are arranged horizontally to be able to reciprocate, and below them are an in-mirror lens 27 and a third lens.
The reflecting mirrors 28 are arranged with respective optical positional relationships with each other. The first reflecting mirror unit 25 reciprocates in the left direction in the figure at a speed V, and the second reflecting mirror 26 reciprocates in the same direction at a speed V/2. A charging corona discharger 30 and a transparent master are arranged around the photoconductor drum 29, which is located on the right side of the center inside the apparatus main body and rotates counterclockwise at a circumferential speed V, along the rotation direction. drum 31, full exposure lamp 32,
Magnetic brush developing device 33, transfer sheet conveying device 3
4, a transfer corona discharger 35, a transfer sheet separation device 36, and a cleaning device 37 are arranged, respectively.

The master drum 31 is a cylindrical body made of polyester film with a thickness of approximately 100 μm held by rigid rings on both sides, and the entire body is 50 μm or more relative to the surface of the photoreceptor.
They are provided very close to each other, about 200 μm, so that they can come into contact with and separate from them. The master drum 31 rotates in the same direction and at the same speed at the point of contact with the photoreceptor drum. Inside the master drum 31, a second latent image forming unit 42 houses an exposure lamp 38, a first mirror 39, a second mirror 40, and an open-top corona discharger 41 with optical positional relationships. The discharger 41 is placed stationary with the discharger 41 facing the surface of the photoreceptor. Inside the master drum 31, there is also a grounded conductive fur brush 43 for a counter electrode.
is rotatably disposed in contact with the inner surface thereof, and a static elimination corona discharger 44 is disposed at a position opposite to this on the outer side. A cleaning device 4 is also provided on the outside of the master drum 31.
5 is arranged so as to be able to approach and separate from the surface of the master drum 31. This cleaning device 45 is
It has a rotating fur brush 46 for removing toner and an auger 47 for conveying removed toner.

The developing device 33 includes a rotating non-magnetic sleeve 48.
a developing roller 50 having a magnetic body 49 stationary therein, and impellers 52 and 5 for stirring and charging the developer 51 housed in the device.
3, this developing device may be of other types. The cleaning device 37 is also a conventional device including a foam roller and a rubber blade that can move toward and away from the surface of the photoreceptor. In addition, the transfer sheet feeding devices 54, 55, the fixing device 56, etc. are also conventional ones.

Next, the operation of this device will be explained. An original to be copied is placed on a document table 21 and a presser plate 22 is placed on it. When the print button is pressed, the first mirror unit 25 and the second mirror 26 move to the left to scan the original, and the optical image is transferred to the rotating photoreceptor drum 29 charged by the charging corona discharger 30. It is projected onto a surface, forming a latent image corresponding to the original image. At this time, the master drum 31 is separated from the surface of the photoreceptor, the latent image forming unit 42 inside the master drum 31 does not operate, and the latent image on the photoreceptor drum passes through this and is transferred from the developing device 33. The toner 51 is supplied and developed. The toner image on the photoreceptor drum obtained by the development then passes under the transfer corona discharger 35, which is not activated, and the cleaning device 37, which has been retracted, and is transferred to the photoreceptor drum without being affected by other peripheral devices. It progresses as the drum rotates and reaches the position of the master drum 31.
At this time, the master drum 31 has already started rotating in contact with the surface of the photoreceptor, and the transfer corona discharger 41 in the latent image forming unit 42 is operating. Therefore, the toner image on the photoreceptor that has reached this point is transferred onto the master drum 31. At this time, the lamp 38 in the latent image forming unit may also be turned on. This is because the charge holding the toner image on the photoreceptor is reduced, making it easier for the toner image to separate from the photoreceptor. Therefore, the transfer efficiency is better when the amount of light at this time is larger than the amount of light when forming a latent image, which will be described later, and it is preferable that the light beam is non-directional. At this time, the master drum cleaning device 4
5 is away from the surface of the master drum 31,
The static eliminating corona discharger 44 is also not operating.

After the transfer, the surface of the photoreceptor drum is irradiated with light from the entire surface exposure lamp 32 to erase or reduce the residual potential, so that even if it comes into contact with toner in the developing device 33, it will not attract it. The surface of the photosensitive drum further advances and reaches the position of the transfer corona discharger 35, but at this time the transfer sheet is not yet fed and the transfer corona discharger is not operating. However, the next cleaning device 37
To facilitate cleaning of residual toner on the photoreceptor, the discharger 35 can be caused to generate a corona discharge of a polarity and magnitude that erases the residual potential on the photoreceptor.

When the cleaning by the cleaning device 37 is completed, the photosensitive drum enters its third rotation, and its surface is uniformly charged again by the charging corona discharger 30, and reaches the position of the master drum 31. During this time, the master drum 31 is also rotating once, and the toner image transferred onto the master drum is
From the second rotation, the light is sequentially projected onto the surface of the photosensitive drum by the exposure lamp 38. At this time, the transfer corona discharger 41 does not operate, and the master drum 3
1 rotates very close to and away from the surface of the photoreceptor drum. Because of this gap and because the master drum and photoreceptor drum have cylindrical surfaces,
The light beam for toner image irradiation needs to be as highly directional as possible, and it is also preferable for the light source to irradiate from a long distance optically, so if possible, use a condensing lens or a reflective lens. It is preferable to arrange a mirror or the like within the latent image forming unit 42 as necessary. Furthermore, it is important that the width of the exposure slit, which also serves as the irradiation aperture of the transfer corona discharger 41, be as narrow as possible. By this toner image irradiation, a latent image that is the same as the previous latent image is formed on the photoreceptor drum, and this is developed by the developing device 33. At this time, the entire surface exposure lamp 32 is of course not operating. The toner image on the photosensitive drum obtained by the development is transferred from the paper feeder 54 or 55 to the conveyor 34 in synchronization with this image formation.
Paper cassette 57 or 5 sent through
A transfer sheet 59 or 60 in the transfer sheet 8 is stacked under the transfer corona discharger 35, and the toner image is transferred to the transfer sheet. After the transfer, the transfer sheet is separated from the surface of the photoreceptor by the separating device 36, passes through the fixing device 56, and is discharged to the paper receiver 61.
On the other hand, the cleaning device 3 cleans the surface of the photoreceptor drum.
Under the action of 7, the third rotation is completed. In the case of multiple copies, the surface of the photosensitive drum is then again subjected to the action of the charging corona discharger 30, and the same process is repeated.

When the required number of copies have been made, a voltage is applied to the master drum static eliminator 44, the cleaning device 45 approaches the master drum, and the fur brush 46 rotating at high speed comes into contact with the master drum surface, removing the toner image on the master drum surface. scrape off.
The static eliminator 44, together with the opposite fur brush 43, is used to neutralize the static from the master drum 31 so that the toner can be easily removed, and to perform the next transfer effectively. The scraped toner is fed to the outside of the device or into the developing device 33 by the auger 47. Cleaning of the master drum can be performed at multiple locations as necessary. When the cleaning is finished, the removal device 44 stops operating, and the cleaning device 45
It separates from the surface of the master drum, and the entire process of multiple copying ends.

In the case of single-sheet copying, the toner image first obtained on the photosensitive drum is immediately transferred to the transfer sheet.

In the above embodiment, the photoreceptor and the transparent body are drum-shaped, but they are not limited to this. Either one of them may be web-shaped or endless belt-shaped, or both may be of these shapes. .

In this embodiment, while a large number of copies are being made, there is no deterioration of the toner image serving as the second original, and the latent image is formed directly by transmitted light without using an imaging lens system. Because it is done,
It eliminates the need for a bright light source and saves energy. Furthermore, there is no need for the scanning optical system, especially its return process, to return quickly during image exposure using the first original in multiple copying, so no extra load is placed on the scanning optical system. Furthermore, since the image forming process using the second original can be made faster than that of the first original, high-speed multi-copying can be performed. Further, the device for forming an image based on the second original has a simple structure and is small in size.
In addition, there is no technical sophistication involved, and although the device has a high level of functionality, it can be manufactured at a low cost. Furthermore, in the case of single-sheet copying, if the copy is made using only the scanning optical system for the first original, the machine can be used as a normal copying machine without reducing the first copy time. In addition, since an imaging lens system is not used when forming an image using the second original, the reference paper feeding position of the transfer sheet does not change between copying a single sheet and copying multiple sheets, and therefore a correction mechanism for this does not change. is not necessary.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing each step in the method of the present invention, and FIG. 2 is a configuration diagram showing an embodiment of an apparatus using the method of the present invention. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 3... Document, 9... Transparent body, 29... Photoreceptor drum, 31... Transparent body master drum, 30
...Corona discharger for charging, 35...Corona discharger for transfer, 41...Corona discharger for second original formation and transfer, 42...Second latent image forming unit.

Claims (1)

[Scope of Claims] 1. A step of forming a primary latent image corresponding to an image to be copied on a photoreceptor, a step of developing this primary latent image to obtain a primary toner image, and a step of developing this primary latent image on a transparent material. a step of electrostatically transferring the primary toner image on the transparent body, a step of directly projecting the primary toner image on the transparent body onto the photoconductor to form a secondary latent image, and a process of developing the secondary latent image to form a secondary toner image. a step of obtaining an image, a step of transferring the secondary toner image to a transfer sheet, a step of forming the secondary latent image, a step of obtaining the secondary toner image, and a step of transferring the secondary toner image. A multi-sheet copying method, characterized in that a large number of copies are obtained from the transparent body by sequentially repeating the above steps. 2. A first latent image forming means for forming a latent image on the photoreceptor; a developing means for developing the latent image on the photoreceptor to obtain a toner image; a second latent image forming means that directly projects the toner image on the transparent body onto the photoreceptor; and a second transfer means that transfers the toner image on the photoreceptor onto the transfer sheet. forming a latent image corresponding to the image to be copied on the photoconductor, developing the latent image to transfer the obtained toner image to the transparent body, and transferring the toner image on the transparent body to the photoconductor. A multi-sheet copying apparatus characterized in that a latent image is repeatedly formed by projecting onto a surface of a sheet, and the latent image is developed each time and transferred onto a transfer sheet. 3. The transparent body is provided in close proximity to the photoconductor so as to be able to approach and separate from the photoconductor, and when transferring the toner image on the photoconductor onto the transparent body, the transparent body is brought into contact with the photoconductor, 3. The multi-sheet copying apparatus according to claim 2, wherein when the toner image on the transparent body is projected onto the photoconductor, the transparent body is brought very close to the photoconductor.