DE1954472A1 - Electrophotographic process for making a large number of copies from a master copy - Google Patents

Description

EASTMAN KODAK COMPANY, 343 State Street, Rochester, Hew York State, United States of America

Electrophotographic process for producing a large number of copies from a master copy

The invention relates to an electrophotographic process for producing a large number of copies from a master copy, consisting of at least one photographic developed image layer and one photoconductive layer Layer and a practically transparent / conductive layer located between these layers.

electric

It is known, for example from US Pat. No. 2,939,787, to generate an electrostatic image on the latter in a photographic recording material with a photographic layer on one side and a photoconductive layer on the opposite side, to tone the electrostatic image formed, which to use the resulting toner image as a template for exposing the photographic layer and finally civr * ch developing the photographic layer to produce a permanent bill. This

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known two-step process is used to produce a permanent silver image.

It is also known, e.g. B. from the USA patent 3 331 276, to use a temporary silver image as a template for exposing a photoconductive layer »whereupon the exposed, photoconductive layer is a permanent, electrophotographic Image is developed.

In neither of the two known methods can, however, be used Recording material for the production of an electrophotographic master for the production of a variety of Copies are used. Moreover, there is no indication whatsoever in which way from the patent specifications the recording material used in each case for the production of electrophotographic originals for the production of a Variety v, · .. copies could be used.

It is also known, after all, e.g. B. from the USA patent 3 132 963, for the production of a master copy a xerothermographic Laminating recording material onto a photographic slide. For making copies however, the known master copy must be heated. An indication of the possibility of an exposure such as that on electropnotographic Field required is absent from the patent specification.

The object of the invention is to provide an electrophotographic duplicating process indicate that the production of a large number of high quality copies of a single copy template.

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1S5A472

The object of the invention proceeds from an electrophotographic Process for the production of a large number of copies from a master copy, consisting of at least one photographic, a developed image layer and a photoconductive layer and one between these layers located, practically transparent, conductive layer and is characterized in that one

a) uniformly electrostatically charges the photoconductive layer; that he

b) the photoconductive layer through the photographic image and the permeable layer through (to form a the latent, electrostatic image corresponding to the photographic image) exposed to "flood" light (wash light); that he

c) the electrostatic image obtained to produce a toner image used on an image receiving material and that one finally

c) for the production of further toner images from the same master copy the process steps a), b) and c) are repeated.

When Vex'fahren the invention is thus z. B. a master copy used, which was obtained by placing a photographic layer on the transparent, conductive support attached to a photoconductor layer. The photographic layer is then exposed to an original; H. true to image exposed and preferably developed into a slide.

Then the ρ no to le it capable layer is charged and either simultaneously or subsequently to the formation of a latent electrostatic image by the photographic iSild exposed through "flood" light. Finally will

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the electrostatic image obtained in the usual way with HiI- ■ fe a toner, whereupon toner particles of the developed image are developed to form a positive image on an image receiving material be transmitted. To make further copies only the charging, the floodlight exposure, the toning and transfer of the toner particles are repeated.

After the silver image has been produced, a simple one is obtained fold-up positive / positive master copy. Similarly, if you turn the photographic image into a transparent one Developed negative (negative transparency), make negative copies of it. Finally, there can also be a reversal be carried out to develop the non-exposed areas, provided a negative from a slide should be produced or vice versa.

Since the electrophotographic master used in the present invention has a fixed or permanent image, it can be used repeatedly. The copies produced by such a template are characterized by an excellent quality as a substantially Kontaktbelich- f tung takes place through the transparent photographic image therethrough. For this reason, no optical systems are required when carrying out the method of the invention, which is why the costs of the device required for carrying out the method of the invention are low.

The development, e.g. By toning with a brush, results in high density images. Furthermore, it is not necessary that the photographic layer, e.g. B. a silver halide emulsion layer, of the original to be copied is highly sensitive and that development is carried out at high speed since the one to be copied Original is only exposed once.

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Production speed Thus the - the copier not by the speed of photographic development, but rather by the speed at which the master can be prepared again for the production of a new copy, and the speed with which one the photoconductor recovers is determined. Finally, the exposure of the photoconductive layer takes place through their Underlay or its support, so that a sole improvement of the image quality by / S on the photoconductive Surface is prevented.

The invention is explained in more detail below with reference to the drawing. explained. Show in detail:

1 shows a cross section through a master copy suitable for carrying out the method of the invention, the photoconductive layer of which is charged after an image is developed;

Fig. 2 shows the formation of an electrostatic image on the photoconductive layer by "flood" light exposure the photoconductive layer through the transparent image;

3 shows the development of the electrostatic obtained Image to a toner image;

4 shows the transfer of the toner image obtained to a Image receiving sheet and

5 shows a continuously operating copier in which the method steps shown in FIGS. 1 to 4 can be carried out.

/ unused, accumulated remnants of the toner

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According to Pig. 1, the electrostatic copy master V used to carry out the method of the invention consists of a photographic layer 10 deposited on top of a photoconductive Layer 12 arranged, transparent, conductive layer 11 is laminated. If necessary, a not shown Layer support between the conductive layer 11 and the photographic layer 10 be arranged.

In accordance with the present invention, the photographic layer 10 becomes image-correct fe exposed to a radiation pattern, whereupon it becomes a permanent one Image, for example a slide with translucent areas 13 and opaque areas 14, is developed. This photographic image forms a permanent master copy that can be used over and over again to produce a multitude of copies can be used.

The first step in using such a master copy is shown in FIG. The photoconductive layer 12 is then electrostatically charged, for example with the aid of a corona discharge device 15. The photoconductive layer 12 is then exposed through the transparent layer 11 to "flood" light 16 (wash light), where w on the Photoconductive layer 12, a ^{latent, electrostatic image corresponding to the opaque areas I 1} J of the photographic layer 10 is generated. The electrostatic image obtained is then toned, as shown in FIG. A toner image 19 is thereby obtained. Finally, as shown in FIG. 4, the resulting toner image 19 can be transferred to a receiving sheet 20 by bringing the latter into contact with the toner image.

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To facilitate the transfer. Can use the image receiving sheet 20, for example with HHfe a roller 21 is given a bias will.

The master copy V can now be recharged with "flood" light exposed and toned, whereupon the new toner image can be used to make further copies.

The master copy can be stored indefinitely and reused many times. Since the exposure through the

occurs through it is the tendency

image degradation due to foam formation on the surface of the photol it-capable layer 12 is lower.

The photoconductive layer 12 can also be used, if desired clean, whereby any toner particles that may be present in the non-image areas can be removed.

In the device shown schematically in FIG. 5, all of the method steps shown in FIGS. 1 to 4 can be carried out continuously. In this case, an original V is rotated on a drum. The photoconductive layer 12 ′ is then again electrostatically charged, for example with the aid of a corona discharge device 22. As the drum continues to rotate, the photoconductive layer 12 'is exposed to "flood" light 23 ^{through the image 10' and through the layer II 1 behind.}

The resulting on the photoconductive rail 12 ', latent, electrostatic image is then moved past a development station 24 and developed. The development takes place in the present case by cascade development. However, other development methods can also be used, for example with a magnetic brush. In the case of cascade development, the excess developer particles can be stored in

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a receptacle 25 charged and with the help of not shown Device parts returned to the development station will. The toner image obtained is then applied to an image-receiving sheet 26 running over a transfer roller 27 transferred, the transfer roller 27 for relief the transmission may have an electrical bias. As shown, the image receiving sheet can consist of an endless one Or consist of individual sheets.

Due to the "flood" light exposure through the image on the transmissive photographic layer, which is connected to the photoconductive Layer is connected or otherwise related, contact exposure is practically achieved. After this Once the permanent image on the permeable photographic layer has been developed, the structure can be considered repeated usable and storable without special treatment Serve as a template. It is only necessary to charge the photoconductive layer through the transparent image to expose through it with "flood" light that is on the photoconductive Layer to tone the resulting electrostatic image and finally the toned image to an image receiving material transfer. Thus, after the photographic image has been developed, exposure is not required for production to make copies within a certain critical period. The one working with such a master copy Furthermore, the copying device does not need to have any complex optical systems, which is why such a device can be created relatively cheaply.

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Claims (1)

PATENT APPLICATION Electrophotographic process for the production of a variety of copies from a master copy, consisting of at least one photographic, a developed image having Layer and a photoconductive layer as well as a practically transparent, located between these layers ) conductive layer, characterized in that one 'electric a) the photoconductive layer uniformly electrostatically charges; that he b) the photoconductive layer through the photographic Image and the conductive layer through it (for training a latent, electrostatic image) exposed to "flood" light; that he c) the electrostatic image obtained to produce a Toner image used on an image receiving material and that one finally d) for the production of further toner images from the same master copy the process steps a), b) and c) are repeated. Process according to Claim 1, characterized in that the electrostatic image obtained according to b) is mixed with a toner developed; that one the obtained toner image on an image receiving material and that the process steps are used to produce further toner images from the same master copy Wieciernolt. 3. The method according to claims 1 to 2, characterized in that iuäa is based on a master copy,! .- ■■; I said photogi'ai'ifccn-: vJehioüt ouch a slide i .. -teilt _s and that da-i ernaitene eiektrostatlsche image to eir ^ s: · -; '.;,;,:' Em slide ο ;; i-; tön-Jer * _s po ^ iiiven toner image developed, 009819/1702 Blank page