JPH0222379B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-sheet copying method for forming an intermediate original and thereby obtaining a large number of copies in an electrophotographic method.

2. Description of the Related Art Methods of making multiple identical copies of a conventional original are known. In particular, as a method of obtaining many copies by exposing the original once, there is
As disclosed in No. 22829, at the time of transcription,
With the transfer body superimposed on the visible image on the photoreceptor,
There is a method of obtaining a large number of copies by exposing the entire surface of the transfer member from the back side and creating an electrostatic latent image on the photoreceptor again. In addition to this, there are other conventional methods such as those described in the above-mentioned Japanese Patent Application Laid-Open No. 54-22829. Many of these conventional methods have been proposed to electrostatically retain a visible image using toner, but each method has a limit to the number of times it can be repeated. Even in this case, it was impossible to repeatedly make 100 or more identical copies. Furthermore, as disclosed in Japanese Patent Application Laid-Open No. 54-22829, a method in which a visible image formed by toner on a photoreceptor is used as a document and an electrostatic latent image for the next time is created in a relay manner does not require the same Each later copy usually has more flaws than the previous one because it cannot maintain a continuous visible image of the image. Therefore, like many other methods, the number of iterations is limited, resulting in copy degradation. In addition, since the remaining toner is charged from above without being cleaned, the polarity of the remaining toner is reversed.
As a result of the toner being subjected to a cleaning action in the developing device, there is a drawback that the background of the copy gradually becomes smudged.

The multi-sheet copying method according to the present invention includes a first latent image forming step of irradiating a photoreceptor with a light image of the original to form an electrostatic latent image, and a first step of making the electrostatic latent image visible with toner. a developing step, an intermediate document transfer step in which the visible image formed by the toner is transferred as an intermediate document to a translucent and adhesive intermediate document holding member by transfer pressure, and after completion of the intermediate document transfer step,
a second latent image forming step of forming an electrostatic latent image similar to that of the original optical image using transmitted light obtained by closely contacting the intermediate original holding member holding the toner image with the photoconductor; A second developing step for converting the electrostatic latent image obtained in the latent image forming step into a toner image, and a step for transferring the toner image to a transfer body for fixing the permanent image, the second latent image forming step and , a second development step;
The present invention is characterized in that a large number of copies are obtained from the intermediate original by sequentially repeating the transfer process.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-copying method that can produce a large number of clear identical copies in a short time by combining simple steps and consumes less energy.

The present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram for explaining the process of the invention. First, charging (a), exposure (b), and development (c) in ordinary indirect electrostatic photography are performed. That is, as shown in FIG. 1a, the photoreceptor 1 is uniformly charged with a positive charge by the corona charger 2 in the dark, and then a light image of the document 3 is irradiated onto the photoreceptor 1. An electrostatic latent image corresponding to the original optical image is formed, and a first latent image forming step is performed. Next, as shown in FIG. 1c, the electrostatic latent image is visualized with colored toner 4 having an opposite polarity, that is, a negative charge, and a first developing step is performed. Thereafter, the intermediate document holding member 5, which is made of an elastomer layer 501 that is translucent and adhesive to the toner 4 at room temperature and is formed in the shape of an endless belt, is transferred to the photoreceptor 1 by a transfer pressure roller 511. Pressed. Due to the transfer pressure in this case, the visible image of the toner on the photoreceptor 1 is transferred to the intermediate document holding member 5 as an intermediate document, and an intermediate document transfer process is performed. In this way, the intermediate document forming cycle A is completed. As a result, the intermediate original holding member 5 holds an intermediate original that forms the same optical image as the original 3. Note that if a visible image is transferred to transfer paper 7 instead of this intermediate document holding member 5, a normal one-sheet copy can be obtained. After this, the multi-sheet copying cycle B begins. First, the photoreceptor 1 is cleaned by the cleaning roller 61 (see FIG. 1e). Next, the entire surface of the photoreceptor 1 is charged by a corona charger 2 (see FIG. 1f). Thereafter, the intermediate document holding member 5 that held the intermediate document during the intermediate document forming cycle A is brought into close contact with the photoreceptor, and uniform light is irradiated from the back side thereof. The transmitted light thus obtained, that is, the optical image of the intermediate document, is irradiated onto the photoreceptor 1 (see FIG. 1g), and an electrostatic latent image identical to that of the document 3 is formed.
A latent image forming step is performed. Thereafter, as shown in FIG. 1h, the photoreceptor 1 is developed with the toner 4, a second development process is performed, and the visible image formed by the toner 4 is transferred to the transfer paper 7 superimposed thereon on the charger 8. (see FIG. 1i), and a transfer process to a transfer body is performed. The visible image formed by the toner on the transfer paper 7 is then fixed onto the transfer paper 7 as a permanent image. In this way, the cleaning process from FIG. 1e to FIG. 1i, the second latent image forming process,
A desired number of copies can be obtained by repeating the second development step and the transfer step to the transfer body to perform a multi-sheet copying cycle B. There is no need to increase the contact pressure of the intermediate document holding member 5 to the photoreceptor 1 in the second latent image forming step in this multi-sheet copying cycle B, and it is simply necessary to ensure that relative displacement with respect to the photoreceptor 1 does not occur during exposure. It is sufficient if the pressure is applied to an appropriate degree. On the other hand, the intermediate document holding member 5 in the intermediate document forming cycle A needs to be pressed against the photoreceptor 1 with a certain amount of transfer pressure so as to adhere the visible image of the toner on the photoreceptor 1. For this reason, it is desirable to maintain the transfer pressure at a predetermined level during the intermediate document transfer process, and to reduce the adhesion pressure below the transfer pressure during the second latent image forming process in the multi-sheet copying cycle B. This makes it possible to reliably hold the visible image of the toner on the intermediate document holding member 5 as an intermediate document, and since the adhesion to the photoreceptor 1 is reduced during the multi-sheet copying cycle B, the intermediate document holding member 5
The durability of the material is improved. Furthermore, the time required for the intermediate document forming cycle A may be longer than the time required for the multiple copying cycle B.

As described above, the intermediate document forming cycle A and the multi-sheet copying cycle B differ in the appropriate time required for each latent image forming step and each transfer step. For this reason, the time required for each step in the intermediate document forming cycle A may be made longer than that in the opposing multi-sheet copying cycle B to ensure that the intermediate document and the original are created with the same light image. . Furthermore, by doing so, the time required for the multi-sheet copying cycle B may be shortened so that a large number of copies can be obtained at high speed.

After the intermediate document forming member 5 is used in the multi-sheet copying cycle B, that is, after being used in the final second latent image forming step, the visible image formed by the toner held on the surface of the intermediate document forming member 5 is transferred to a cleaning roller as a cleaning member. 28 (Fig. 1j,
(see k). In this intermediate document forming member cleaning step, the intermediate document forming member 5 is heated by the heater 29 so that its adhesiveness is weakened and the releasability of the toner 4 is increased. Further, a cleaning roller 28 is pressed against the intermediate document holding member 5, and a visible image formed by toner is adhered to the cleaning roller 28 side. In this case, it is desirable that the intermediate document forming member 5 is not brought into close contact with the photoconductor 1 as much as possible to prevent the photoconductor 1 from being heated by the heated intermediate document forming member 5. For this reason, the contact pressure of the intermediate document forming member 5 to the photoconductor 1 may be reduced, or the intermediate document forming member 5 may be completely separated from the photoconductor 1 to restrict heat conduction to the photoconductor 1 during the cleaning process. . Through this cleaning process of the intermediate document forming member 5, the intermediate document holding member is used repeatedly.

When the multi-sheet copying method described above is carried out, the intermediate original only receives transmitted light from the light source 33 on the intermediate original holding member 5, and there is almost no deterioration, so that a large number of copies of the same image can be continuously obtained. According to this multi-sheet copying method, the light source light directly passes through the intermediate document holding member 5 and exposes the photoreceptor, so the light source 33 can be small and the exposure efficiency is high, resulting in high speed and energy saving. Moreover, since the exposure is performed using the light image of the intermediate document that is in close contact with the photoreceptor, there is no blurring and no image distortion or fogging occurs due to repetition. Further, by reducing the speed of the intermediate document forming cycle A compared to the speed of the multi-sheet copying cycle B, it is possible to improve the quality of the intermediate document and also to improve the processing speed of a desired amount of identical copies. . Moreover, when performing the intermediate document forming cycle A, the transfer paper 7 as a transfer body is switched from the transfer to the intermediate document forming member 5.
By transferring a visible image using toner to the paper, it is possible to obtain one copy from one ordinary original. In this case, since there is no need to perform the step of transferring a visible image using toner to the intermediate document forming member 5, one document can be made in the same amount of time as it takes to obtain a first copy from one document.
You can get a copy.

FIG. 2 shows an example of a multi-sheet copying apparatus C capable of carrying out the above-described multi-sheet copying method. The configuration of this device and the one-exposure, one-sheet copy cycle using this device will be explained. The photosensitive drum 11 has a photoconductive insulating layer on its surface 111, and is rotated in the direction of the arrow shown. On the upper side of the photoreceptor drum 11, an exposure device 8 made of a light-converging light transmitting member is disposed opposite to the photoreceptor drum 11, and forms an optical image of the original onto the photoreceptor surface 111. The original 3 is guided by a transparent original placing table 31 that moves at a constant speed in a fixed direction, is irradiated by an original illumination light source 32, is slit exposed by an exposure device 8, and is placed on a photoreceptor drum 11 in a manner corresponding to the original light image. Forms an electrostatic latent image. Prior to this, the entire surface of the photosensitive drum 11 is uniformly charged by the corona charger 2 in the dark. In the rotational direction of the photosensitive drum 11, following the exposure device 8, the developing device 9, the transfer corona discharger 21, the separating device 22, the cleaning device 6,
A corona charger 2 and an intermediate document forming member 5 are arranged in a row. The electrostatic latent image formed by the exposure device 8 is visualized by the developing device 9. The toner concentration in the developing device is detected by a toner concentration sensor (not shown), and if necessary, toner is replenished from a hopper 91 to keep it constant. This visible image is conveyed by the photosensitive drum 11 and is opposed to the transfer corona discharger 21 . At this time, a transfer paper 7 supplied from a paper feed tray 24 is arranged in synchronization between the discharger 21 and the photoreceptor drum 11, and the visible image on the photoreceptor drum is transferred to this transfer paper 7. The image is transferred by the electrostatic force of the corona discharger 21. After this, the transfer paper 7 is separated by a well-known separating device 2.
2 and is separated from the photoreceptor drum 11, and is melted and pressed by a pair of heat rollers 251 and pressure rollers 252. The visible image formed by the toner is fixed on the transfer paper 7 as a permanent image by the fixing device 25 composed of the pair of rollers 251 and 252. Thereafter, the transfer paper 7 is guided onto the paper discharge tray 27 by a pair of paper discharge rollers 261 and 262. On the other hand, transfer paper 7
Thereafter, the photosensitive drum 11 that has sent out the toner is cleaned of residual toner by a well-known cleaning device 6, completing the cycle of one exposure and one copy.

Next, in order to carry out the multi-sheet copying method of the present invention using this multi-sheet copying apparatus C, first, 1 exposure 1
Exposure and development are performed in the same way as in the sheet copying cycle. Thereafter, instead of being transferred to the transfer paper 7, the image is transferred to the intermediate document forming member 5. This intermediate document forming member 5 is constituted by an endless belt (hereinafter referred to as an elastic belt) 51 having an adhesive and transparent elastomer layer, and has one belt perpendicular to the photoreceptor drum 11.
It is pressed by a pair of transfer pressure rollers 511 and 512, whereby the visible toner image is adhered to the elastic belt 51. In this case, an elastic belt 51 having a polyimide film of 100 [μ] and a silicone rubber layer of 25 [μ] is used, and the transfer pressure is set to 0.5 [Kg/
cm ² ] and a speed of 100 to 300 [mm/sec], a transfer rate of 80 [%] or more was obtained. In this way, the intermediate document forming cycle A is completed, and then the photosensitive drum 11 is cleaned by the cleaning device 6 and charged by the corona charger 2. Next, the elastic belt 51, which is in close contact with the photosensitive drum 11 under a constant pressure, is uniformly illuminated within a constant width by the light source 33 on the back side thereof. As a result, the transmitted light reaches the photoreceptor surface 111, and an electrostatic latent image corresponding to the intermediate document optical image is formed. After this, the electrostatic latent image is transferred to the developing device 9.
The visible image formed by the toner is transferred to a transfer paper 7 by a transfer corona discharger 2.
and is transferred to the transfer paper 7 by the separating device 22.
is separated from the photoreceptor and then fixed by the fixing device 25. In this manner, the multiple copy cycle B is repeated until a predetermined number of copies of the same image are obtained. After completing the multi-sheet copying cycle B,
The elastic belt 51 is heated by the heater 29 and then pressed by the cleaning roller 28 to cause toner to adhere to the cleaning roller 28 side. In this multi-sheet copying device C, the cleaning roller 28
If the pressure against the toner is maintained at 2 [Kg/cm ² ], the toner
The transfer rate is almost 100%, and the elastic belt 51
received very good cleaning action. And for such cleaning operations, this device C can withstand tens of thousands of repetitions. Since this elastic belt 51 is extremely thin, even if it is heated before cleaning, the temperature rapidly decreases after that, so even if it comes into contact with the photoreceptor drum 11 again, the photoreceptor surface 11
The temperature of No. 1 does not rise much. For this reason, the photoreceptor surface 111 does not change due to heat, but if necessary, means may be provided to reduce the contact pressure to the photoreceptor drum 11 in stages. In this multi-sheet copying apparatus C, the light source light is directly transmitted through the elastic belt 51 to expose the photoreceptor surface 111 during exposure without using an optical system such as a lens mirror. Since the exposure efficiency is higher than that of exposure, the light source 33 can be made smaller and energy can be saved. Furthermore, in the multi-sheet copying cycle B, there is no need to move the original for scanning the original, and there is no load on the apparatus C, which has the advantage of extending the useful life of the apparatus C. Furthermore, in the multi-sheet copying cycle B, the intermediate original holding member 5 performs close exposure to the photoreceptor and no lens system is used during exposure, compared to the case where the photoreceptor is exposed multiple times using a lens system. Therefore, the reference of the paper feeding position does not change in the left-right direction, and a correction mechanism for this is not necessary.

Although the multi-sheet copying apparatus C shown in FIG. 2 uses the photosensitive drum 11, this is not particularly limited, and a well-known endless belt-shaped photosensitive drum may also be used. Furthermore, a visible image of toner is transferred onto the elastic belt 51 with a predetermined transfer pressure; in this case, the toner 4 is transferred to the elastomer layer 5.
Since the toner 4 is adhesively attached to the photosensitive drum 11, it can withstand operations of contact and separation from the photoreceptor drum 11, but if necessary, the toner 4 can be heated with a heater to temporarily fix it and used as an intermediate document. Good too.

Furthermore, the material of the endless belt may be changed to a material that exhibits mold releasability at high temperatures, such as Teflon resin.

The intermediate document holding member 5 of the multi-sheet copying device C shown in FIG. 2 was an elastic belt 51, but instead of this, it is a transparent cylinder 52 having an elastomer layer 501 on the outer surface as shown in FIG. may be configured. In this case, the transparent cylinder 52 is made of a material such as glass, quartz, sapphire, etc., and preferably has heat resistance. In this case, the photoreceptor surface 11
Since the intermediate original is in only line contact with the intermediate document 1 and not in surface contact like the elastic belt 51, it is necessary to irradiate the slit with a directing light beam during exposure. For this purpose, for example, as shown in FIG. 3, a light source 33, a convex mirror 34, a plane mirror 35, a concave mirror 36, and a slit plate 37 are configured to irradiate the photoreceptor surface 111 with a slit beam having a directing property. . In the figure, 28 is a cleaning roller, and the elastomer layer 501 is a heating heater 29.
When heated, this cleaning roller 28 is pressed against the transparent elastomer layer 501. In this case, since the elastomer layer 501 is heated and exhibits releasability, the toner forming the intermediate document held on its surface easily adheres to the cleaning roller side. FIG. 4 shows an intermediate document forming member 5 having a transparent cylinder 52 shown in FIG.
is installed, and the other configuration is the same as that of the multi-sheet copying apparatus C shown in FIG.
1 is shown. Since the transparent elastomer layer 501 used in this device C1 is reliably supported by the transparent cylinder 52 as a base, the amount of deformation is less than that of the elastic belt 51 shown in FIG. 2, and the durability is high. There are advantages.

In each of the above-mentioned embodiments, a light-converging light transmitting body is used in the optical system as the original exposure device 8, and an original moving type is used as the original scanning means, but a well-known mirror and lens system is used. It is also possible to use a full-surface exposure system, and there are no particular limitations.

Further, in each of the above-described embodiments, an endless belt and a cylinder-shaped intermediate document holding member 5 are shown, but a long web-shaped member (not shown) may also be used. In this case, the intermediate document holding member 5 can sequentially hold and store different documents one after another. Therefore, by repeatedly exposing the web of a series of intermediate document groups while winding and rewinding them, it is possible to obtain copies with the same page order.
There is no need for a document feeder, etc., and the document only needs to be fed once, so damage to the document can be prevented.

As mentioned above, this multi-sheet copying device has a simple structure and is small in size, does not require very advanced technology, and can be made small and inexpensive even though it has effective functions as a device. There are also advantages.

[Brief explanation of drawings]

FIG. 1 is a process explanatory diagram of the multi-sheet copying method according to the present invention, FIGS. 2 and 4 are schematic side views of different apparatuses for carrying out the multi-sheet copying method according to the present invention, and FIG. 3 is FIG. FIG. 3 is an enlarged view of an intermediate document forming member used in the apparatus shown in FIG. 1...Photoconductor, 3...Original, 4...Toner, 5
...Intermediate document holding member, 7...Transfer body, 28...
Cleaning member, 29...Heater, A...Intermediate document forming cycle, B...Multi-sheet copying cycle.

Claims (1)

[Scope of Claims] 1. A first latent image forming step in which an electrostatic latent image is formed by irradiating a photoreceptor with a document optical image, and a first developing step in which this electrostatic latent image is visualized with toner. , an intermediate document transfer step in which the visible image of this toner is transferred as an intermediate document to an intermediate document holding member having translucency and adhesiveness by transfer pressure; a second latent image forming step of forming an electrostatic latent image similar to that of a document optical image using transmitted light obtained by closely contacting an intermediate document holding member holding a toner image; and a second latent image forming step. a second development step of converting the obtained electrostatic latent image into a toner image;
a step of transferring the toner image to a transfer member for fixing a permanent image;
A multi-sheet copying method for obtaining a large number of copies from the intermediate original by sequentially repeating a developing step and a transfer step. 2. The multi-sheet copying method according to claim 1, wherein the contact pressure in the second latent image forming step is reduced by the transfer pressure in the intermediate document transfer step. 3 After the final second latent image forming step of the intermediate document holding member 5 having translucency and adhesiveness is completed, the surface of the intermediate document holding member is heated and at the same time is pressed into contact with the cleaning member to be held on the surface. 3. The multi-sheet copying method according to claim 1, further comprising a step of cleaning an intermediate document holding member in which toner is removed. 4. A patent claim for reducing the contact pressure of the intermediate original holding member against the photoreceptor during the cleaning process of the intermediate original holding member having the translucent property and adhesive property after the final second latent image forming process is completed. A multi-sheet copying method as described in scope 3. 5. Claims 1, 2, or 3, wherein the transfer speed to the translucent and adhesive intermediate document holding member in the intermediate document transfer step is lower than the transfer speed to the transfer body. 4. The multi-sheet copying method described in item 1 or 4.