DE1772456A1 - Photoelectric reproduction method and apparatus and paper for practicing the same - Google Patents

Description

ermann

Munich 2, _ioSfN , _W7
'^ • 261989

May 17, 1968

ANICET ANSTAIT Soc. An., Vaduz (Liechtenstein)

Photoelectric reproduction method, and apparatus, and Paper to pursue the same.

The priority of French patent application No. 107.717 of 24 May 1967 has been claimed.

The present invention is directed, and particularly, to a method of photoelectric reproduction a new xerographic process for the division of faithful Copies of documents outgoing from opaque or translucent originals.

This procedure enables playback on

lightweight, cheap papers, which also form an object of the invention to the extent that they relate to a particular one in the manner described below.

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ORIGINAL INSPECTED

The invention also includes the apparatus required to practice this new xerographic process Object.

The usual xerographic technique can currently be based on. two methods recalled below returned v / earth. The first method is to contact or optically the document to be reproduced to expose a metal plate or drum coated with a thin photoconductive layer previously charged is. In most cases this will be the photoconductive layer formed by amorphous selenium, which is applied in a vacuum to a plate or drum made of previously appropriately treated aluminum became. This selenium layer holds back the electrical charges in the dark and releases them with actinic lighting free. If after charging this surface in the dark an optical image of the document to be reproduced projected onto it, they keep the dark areas of the document (black lines of a letter or an image) corresponding places on this surface give their electrical charge, while those corresponding to the "white areas" of the document Make lose their cargo. This gives an electrostatic one Image of the document. It will then turn this layer in the dark with a finely divided electroscopic Powder dusted, which adheres to the places that have retained their charge, with an electrostatic Image of the document is created. A sheet or strip of paper is in turn in contact with the platen or drum in the dark brought. The particles of the electroscopic powder are applied to the paper on which the reproduction is to take place by means of

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an electric charge applied to the back of the paper. These particles are temporarily attached by induction on the paper, and after an infrared treatment, a permanent, high-contrast, fixed one is obtained on this paper Document · Note that the amorphous selenium photoconductive surface is a P-type conductor, which is only one can accept positive charge, which requires the use of a negatively charged electroscopic powder.

The second popular xerographic method the document is reproduced directly on a photoconductive surface located on a sheet of paper. In this pail is the photoconductor, generally zinc oxide, finely dispersed in a highly insulating varnish, which is applied in the form of a thin layer to ordinary paper will. This zinc oxide-containing layer then becomes electrostatic charged in such a way that it has a negative polarity compared to the paper backing. Then it becomes more known per se Way (illumination of the document and projection of the motif of the same by an optical system) this layer is to be reproduced Document exposed. The electrostatic image obtained on this layer is then obtained by means of an electroscopic Developed substance which was applied to the photoconductive surface by known methods, either in a smoke chamber, or in a liquid insulating medium (Petroleum, etc.), which is dispersed and held in suspension Contains carbon black, or by means of a magnetic brush, or by directly applying a positively charged one electroscopic powder.

These two well-known xerographic metrics

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methods have significant disadvantages:

The first method is the apparatus

sensitive and their maintenance, which represents a large part of the price of the copy, since this is on almost ordinary Paper is produced, increases this cost price to a considerable extent.

There is a second disadvantage to this method

in that the drum carrying the photoconductive layer is periodically cleaned after each reproduction has been made nut to remove the remaining electroscopic powder. Although this cleaning is done with v / calibrated rotating brushes is made, the photoconductive layer is attacked, the thickness of which must be kept precisely constant (about 20 microns). This causes distortion during playback.

The second method above gives expensive copies,

da.jede copy a photoconductive layer on one side of a Has paper backing, which had to be coated with a thin layer of zinc oxide. For this purpose, the zinc oxide is initially fine ground and dispersed in a highly insulating and hydrocarbon soluble binder. To prevent the Solvent while painting the photoconductive To prevent layer, the paper is carefully coated on the front and back with another suitable varnish, which in which the hydrocarbon is insoluble. The manufacture of such a paper on an industrial scale, in which the thickness of the photoconductive layer can be kept constant at 2 or 3 microns for a useful thickness of about 15 to 20 microns must, and the during the painting with the help of special Accuracy required by spreaders are factors which

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ORK3INAL

. considerably increase the asking price of this Paris and the yield reduce this method. Furthermore, the paper used is ■ very difficult. The combined weight of the backing and the photoconductive Layer reaches about 120 g / m, while the weight of a common paper for office purposes is of the order of magnitude 60 g / m.

In summary, it can be said that that

Weight and the high price of this paper use this second method as a reproduction technology on an industrial scale.

The inventive method allows | to remedy the above disadvantages by the fact that it has a low cost price, that it is easy by means of a simple apparatus to be maintained can be exercised, and that a common, lightweight, inexpensive paper is used for reproduction Furthermore, the method gives a very faithful reproduction of the original, even of its semitones, it can used for panchromatic reproduction, and allows a certain number of identical copies to be easily made.

This process is essentially due to this characterized in that the original to be reproduced forms an electrostatic image on a photoconductive surface which is supported by a static electricity conductive pad that has an insulating surface of a non-photosensitive and non-photoconductive paper sheet or the like. is charged evenly with static electricity, that thereupon in the dark this photoconductive surface with the insulating surface in contact or in immediate Near the same, the zone in which

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These two surfaces are exposed to the action of an electric field, which is a high frequency component and has a DC component before separating the photoconductive surface from the paper sheet the electrostatic image formed on the insulating surface of this paper sheet is developed in a manner known per se and is fixed.

The reproduced original can be printed, be written in pencil or ink, colored or black-and-white and of an opaque durchschei- * nenden or transparent support to be worn. This base can be a paper or a plastic skin or any other suitable type of base that can accommodate letters, characters or motifs. This original can be formed by a paper, a membrane or a plate, which can be light-sensitive or light-insensitive and bears a motif (text and / or drawings) which have been obtained by any photographic, xerographic or other method. This motif can be a positive or a> negative. By the way, Bs can correspond to a straight or a laterally reversed image.

The photoconductive surface on which the first electrostatic image is formed is on the base at least one of the following compounds produced: zinc oxide, cadmium sulfide, anthracene, triazoles, oxaziles, thiazoles, Triazines etc

Palis the chosen photoconductor is zinc oxide, the one given to the photoconductive surface is uniform charge a negative charge, so that that of the insulating surface The uniform charge to be given to the paper is negative

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have to be. With other photoconductors, the photoconductive surface must be given a positive charge so that the insulating surface must be positively charged. In general it is essential that this insulating surface and the photoconductive surface have static charges of constant character.

The concept of mutual contact this

both surfaces has not yet been defined. The immediate proximity of these two surfaces means that these two surfaces are arranged at such a mutual distance from one another that the reproduction takes place with the same results as if they were in contact with one another with otherwise unchanged conditions of the method. This pail can correspond to the presence of a free space of small dimensions, generally occupied by air, between the two surfaces, which then preferably lie opposite one another. It can also correspond to the case that the bases of these two surfaces are opposite one another, or also that the two surfaces are in contact with one another. Different types of intermediate layers that are not connected to the supports can also be provided between these surfaces. According to one characteristic of the invention, the distance between the two surfaces is between 0 and 120 microns, this latter value corresponding to the upper limit of what is to be understood by "immediate proximity". -

The DC voltage component of the electric field is preferably produced by a DC voltage source which is connected to a conductive holder of the paper sheet. This constant component can also be the induction

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effect, which is generated by an electret, whichever is located in the vicinity of the zone in which the two mentioned surfaces are in mutual contact or in close proximity to one another.

A further characteristic of the invention the high frequency component must correspond to a frequency which is between 1.2 kHz and 3000 MHz and preferably between 15 kHz and 3000 MHz. This frequency can be through any device known per se are supplied, in particular a high-frequency oscillator.

The zone of the two surfaces in which

this the effect of the electric field with high frequency component can be more or less extended. This zone, which is in principle fixed in space, can be compared to the both surfaces be movable or immobile, depending on whether it is a continuous or a discontinuous process. In the case of a continuous process the two surfaces move at the same speed at the location of this zone for such a long time that the entirety of the subject to be reproduced (i.e. the electrostatic Image that appears on the insulating surface from the electrostatic image of the photoconductive surface is to be formed) passes through this zone. In the case of such a continuous process, this zone preferably has a small width on the order of a few Millimeters, so that the final electrostatic image can be obtained by scanning (in successive parallel rows) the formed on both surfaces by the electric field.

Under the term "paper or the like"

or simply under the expression "paper" used below

1 0 9 8 1 5/1 b 2 6

■ _m Is to be understood as a cellulose paper or a plastic membrane of a suitable type or any other suitable thin base. In general, for the economy of the process, it will be a sized or glued cellulose paper of the usual type. It is essential that such a "paper" has at least one insulating surface for the formation of the electrostatic image under the "conditions of the process according to the invention. The presence of this insulating surface can result from the paper itself being sufficiently dry and insulating over its entire thickness or an insulating layer which is applied to the paper by any suitable means or which is formed in an original surface layer of this paper, for example by absorption and / or brushing.

According to a further characteristic of the invention, a paper of the usual type, e.g. for office purposes, is used which has been treated or which has been produced in this way, that it has an outer insulating layer on at least one side, which extends over the entire thickness of the paper can extend. This layer is preferably made by dispersing an insulating substance in a suitable binder educated. The weight of such a paper used in the method according to the invention can be of the order of magnitude 40 to 70 g / m 2 and preferably in the vicinity of 55 g / m.

The invention is explained below by way of example with reference to the drawing.

Fig. 1 is a schematic view of a

first device for the continuous exercise of the erfindungagemässen Procedure. -

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Pig ·. 2 is a schematic view of FIG

Discharge zone of the device of the Pig. 1 on a larger scale, A symbolic representation for the distribution of the charges has been chosen to reflect the assumed mechanism of the charge driving to show.

Pig. 3 is a schematic view showing

the principle of the invention in the pail of a discontinuous Procedure shows.

Pig. Fig. 4 is a schematic of an embodiment modification of the arrangement of the pig. 3 corresponding fundamental Opinion·

Pig. 5 shows a schematic view of a second device for carrying out the method according to the invention

Pig. 6 is the cross section of a device

the scorotron type for the uniform uniform electrostatic Charging a surface.

Pig. 7 is a schematic view of a

third device for performing the method according to the invention .

Pig. 8 is a schematic view of a

fourth device for performing the method according to the invention .

The device of the pig. 1 has two metal drums with parallel axes 3 and 4, which in the sense indicated by the arrows, a sheet of paper with photoconductive;

j surface 2, hereinafter referred to as "photoconductive paper", and \ can drive a light sheet of paper with insulating surface 1. These drums have the same diameter and rotate at the same speed

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stored from insulating material. The distance between drums 3 and 4 is dimensioned so that the distance between the photoconductive surface of the photoconductive paper 2 and the insulating Surface of the paper 1, which are opposite to each other, is between 0 and 120 microns.

The axes 16 and 17 of the drums 3 and 4, respectively

are via sliding contacts 5 and 6 with an electronic device connected, which comprises a high frequency circuit and a DC circuit. The drum 3 is about one to the Capacitance 7 shunted resistor 12 earthed, and the drum 14 is connected to the high frequency oscillator via the capacitor 18 9 of the high-frequency circuit and via the resistor 11 with a direct current source 10 of negative polarity (stepped down or stepped up rectified mains current) tied together. The oscillator 9 and the positive pole of the DC power source 10 are grounded.

Between the common point of the high frequency circuit and the DC circuit and the earth is a small neon lamp 8 arranged in series with a resistor 13 to which a capacitor is shunted. These The arrangement stabilizes the tension at the point of the axis 17.

The high frequency path is as follows: oscillator 9, capacitor 18, sliding contact 6, axis 17, mass of the drum

4, capacity 14, mass of drum 3, axis 16, sliding contact

5, capacity 7, earth. The capacity 15 is due to each other opposite sections of the two drums 3 and 4 and through the zones of the paper sheets arranged on these sections and by the between the outer surfaces of these Zones located air formed.

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The one from that from the DC power source 10

generated direct current through the path contains the resistor 11, the sliding contact 6, the axis 17 »the HaGse of the drum 4, the Zone 14, the mass of the drum 3, the sliding contact 5, the axis 16, the resistor 12 and the earth.

The device of Fig. 1 works as follows: since the photoconductive layer of the sheet 2 is formed by zinc oxide dispersed in an insulating varnish, this layer was superficially charged in the dark by a glow discharge projected, so that a negative electrostatic image was formed, the ^{areas of the photographic surface corresponding to the "black 1} , ¹ sections of the original" being discharged when the motif was projected. The sheet of paper 1 was charged with static electricity of negative characters and 2 are then attached to drums 4 and 3. The high-frequency oscillator 9 and the direct current source 10 are then switched on and drums 3 and 4 are set in rotation, for example in the direction of the arrows, with the peripheral speed of the drums being set at a speed between 2 cm / s and 100 cm / s. Value set wi When the two sheets have traversed the entire length of their length opposite one another, the two drums are switched off and the sheet 1 is removed from the drum 4.

It will then go through the development of the same

carried out the methods known in electrophotography. The sheet is s.B. Introduced into a Staubkar.iraer, where there was a Cascade of positively charged. elektroslcopi:.; exposed to particles is, or the surface of the breading is i.iit a

109815/1626 ^ ⁰ ORIGINAL

. ■ - 13.- ■

- Sprinkling insulating.'Fluid which contains black particles positively charged in suspension. B _e i of this latter method is carried out the development by a process which is a combination of electrophoresis and Bielektrophorese.

Thereupon the picture is known per se

Methods fixed by the paper sheet to which the particles forming the developer of the electrostatic image are adhered, exposed to the action of a flow of heat, e.g. Infrared radiation.

As soon as the development is carried out, one observes an image on the sheet of paper which is the faithful one high contrast reproduction of the subject of the original document with the finest details. The electroscopic positive ge ** So charged particles were drawn to the tunnels, to v / el chen the negative charge of the paper sheet 1 was not discharged in the zone 14, -It should be noted, that also a faithful The semitones are reproduced, i.e. the "gray tones", where so far the totality of these properties with xerography could not be obtained to such an extent.

Pig. 2 explains the assumed mechanism of selective discharge of the paper 1 in the H zone in more detail. It can be seen in this figure that the photoconductive paper 2 is formed by a paper base 2a and a photoconductive layer 2b, on which the negative charges U ₂ are symbolically represented by small circles, which on this photolefective layer during the optical projection of the Electrostatic image formed on the subject of the original to be reproduced. form. These charges N ₂ , which ^; alternate with uncharged interspaces 2b ', so represent that of this optical pro-

109815/1626 ORIGINAL BATHROOM

'- κ- i772'iE6

jection originating latent image. These charges N ₂ correspond to the "black areas" of the motif of the original, while the spaces 2b 'correspond to the "white areas" of the motif.

It should be noted that the paper base 2a

is a very good conductor for static electricity, while the photoconductive layer 2b forms a chain which alternately contains charged perfect insulators (zones of localization, charges IT ₂ ) and electricity, conductive spaces ■ (spaces 2b *). These spaces 2b ^f are connected to the high frequency circuit and the direct current circuit by a conductive chain *

That wound on the metal drum 4

Paper sheet 1 has a paper base 1a, which is thus a very good conductor for static electricity, and a thin layer 1b made of a plastic forming an insulator. This insulating layer has no photoconductive or photosensitive property. In their upward movement Part of which has not yet reached zone 14, the insulating layer 1b of this sheet of paper is negatively charged, as stated above. The negative charges N <j of this layer are symbolically represented by small circles.

Under the action of the high-frequency component of the electric field, ionization occurs in zone 14 below such. Conditions that a high-frequency plasma forms in this zone, which is a mixture of ions with opposite polarities and electrons. The DC component of the F _e L of examining the discharge of the insulating layer 1b in the sections to produce the same, which charge-free

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Interstices 2b ^{1 of} the sheet 2 are opposite. The high-frequency component enables the activation and equalization of this discharge, which corresponds to the removal of the negative charges IT- from the insulating layer 1b Furthermore, this fidelity of the image proves that there is no discharge of the charges IT- when they are opposite the charged insulators formed by the zones of "localization of the charges ITp" on the photoconductive surface of the sheet 2. The activation of the discharge by the high-frequency component consists essentially in the fact that the threshold of the potential of the discharge of the insulating surface of the sheet 1 is considerably lower than the discharge threshold which would be present if no high-frequency plasma was present as a result of the application of an electric field without a high-frequency component would have been formed in space 14. · ■. ■ "

Dae is in zone 14 on the insulating layer

1b forming electrostatic. Image is reversed (i.e. symmetrical with respect to a plane) with respect to the electrostatic image present on the photoconductive layer 2b. This reverse can automatically when the subject is optically projected of the original document can be compensated for in such a way that one can immediately an original with a not reversed.-motif.-an identical one cannot make reverse rendering correspond. This grain-> Obviously, however, retirement also allows reverse reproduction to get under exit from an original with an inverted motif. Pehlen this compensation results. there & egen

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Reversed reproductions when originating originals with motifs that are not reversed, and vice versa. It should also be noted that the inventive method immediately a "positive" original a "positive" reproduction and a "negative" original corresponds to a "negative" representation, the terms "negative" and "positive" having the same meaning as in photography or ohemical photocopy and are not tied to the presence of electrical charges.

It should be noted that the effect of the high frequency component of the field quickly beyond that of the zone of the closest approach of drums 3 and 4 corresponding space decreases. Beyond this zone there is no ionization of the air more and thus no discharge takes place.

It should be noted that the discharge of the

insulating surface takes place under the above conditions, which are essential for the sharpness and the other properties mentioned of the reproductions produced by the method according to the invention, because the high-frequency plasma of the space 14 forms a store of charged particles of different polarities. It is this supply of ions which leads to the achievement of a uniform distribution of all ionization states, which are favorable for a selective homogeneous discharge of the negatively charged sections of the insulating layer 1b which are located ^{opposite the conductive intermediate zones 2b 1 of} the photoconductive layer 2b. All secondary effects, such as Lichtenberg figures, ramifications, star formations, etc., which occur in the process of transferring charges, are avoided 100%.

Such transfer procedures are e.g.

U.S. Patent No. 2,982,647 dated May 2, 1961, which shows a conversion of a photoconductive

1 0 9 G 1 L, / 1 U 2 G

& ORIGINAL

Surface describes on an insulating surface, but so far only mediocre and industrially unusable ones could not be used Results can be achieved as a result of a large number of secondary ionization effects, which the production of a make an acceptable copy of an original impossible.

The distribution of the negative charges Eg the

photoconductive surface of the sheet 2 is after passage not noticeably changed by zone 14. So there is no transfer of charges from one surface to another instead, but the selective discharge of the charged insulating surface of the sheet 1 by an induction effect, which by the distribution of the charges on the photoconductive surface of the sheet 2 thanks to the action of the high frequency component is produced.

This lack of a change in photoconductive

.tenden surface 2 is proven by the following two experiments; .

One develops and fixes in oneself in the

Xerography known way the sheet 2 after passing through zone 14. An image is obtained which is identical to that obtained by developing and fixing the sheet of paper 1 is obtained, but is reversed with respect to this;

- the charges applied to the surfaces of the two sheets of paper and the remanent charges before and after the copy are measured and it is found that these were not changed during the course of the procedure.

Ea is therefore possible to use a large number of

High quality renderings under starting from the one originally on the electrostatic image formed by the photoconductive layer 2b.

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tend paper 2 for making reproductions of new documents can serve which are different from the previous ones if initially the first electrostatic formed on this paper Image is extinguished by dissipating the residual charges after the print. For this it is sufficient to use the photoconductive paper of the Exposure to infrared radiation and then to darkness for a few moments.

Pig. 3 shows two electrodes which are through

Metal plates are formed, between which a photoconductive Paper sheet 2 and a paper sheet 1 coated with an insulating layer are kept in contact with each other, wherein the photoconductive layer 2b of the sheet 2 is in contact with the insulating layer 1b of the paper sheet 1. On the photolftitenden Layer 2b was formed from an original document, an electrostatic image, in the manner described above. The insulating layer 1b was evenly charged with static electricity, which has the same polarity as the electrostatic image. Electrode 42 is grounded and electrode 43 is connected to a high-frequency oscillator 44 and a direct current source 45. The circuit corresponds in detail, for example, to that in Pig. 1 shown.

Establishing the electrical connection

between the electrodes 42 and 43 enables the simultaneous formation of all parts of the electrostatic image of the sheet 2 on the insulating layer 1b of the sheet 1. Operation is carried out in the dark as above. The upper electrode is made removable by a corresponding sliding or pivoting installation, not shown. A resilient electrical contact 46 enables this removal. After the trigger, the electrical connection with the above circuits is interrupted, and the

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removable electrode 43 is removed, removing sheet 1 of sheet 2 is lifted off. The development and fixation of the electrostatic latent image formed on the insulating layer 1a gives an image which is faithful and correct is a contrasted rendition of the subject of the original document.

The threshold mentioned with reference to FIG of the discharge potential is practically zero due to the presence of the high frequency component. At zero potential (Absence of the DC component), however, the reproductions become frequent too pale, so that in practice the training is so taken | that the potential of the electrode 43 compared to the electrode 42 (Fig. 3) or the drum 4 compared to the drum 3 (Fig. 1) on the order of at least a few tens of volts and preferably is of the order of a few hundred volts.

It should be noted that in the process of

Transfer of loads of American patent No. 2,937,943 there is talk of the application of a critical transfer voltage is. The curves of the drawings of this patent give, for each distance between two conductors, the breakdown voltage of the surrounding ones Breathing in · It should be noted here that, since there is a migration voltage of the charges under critical stress the surrounding air, these curves are an extrapolation of the Townsend curve. When the breakdown occurs an avalanche of electrons as a result of the numerous collisions caused by the applied to the terminals of the electrodes Field accelerated electrons with the atoms of the gas (air).

When forming the subject of the invention

Process, the curves shown in the American patent are irrelevant, since a discharge in a high-frequency

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'plasma is worked under such conditions that the discharge gradually begins at the slightest induction.

The lack of a potential threshold for the

Discharge (critical breakdown voltage) can be demonstrated · ■ that the method still gives the same results works when the DC component of the field is not caused by a DC power source but by the discharge of a Electret is generated. In Fig. 4, which shows this embodiment modification, an electret 48, which is through a ^ A sheet of silicone elastomer in which cadmium sulfide is dispersed is approached to the electrode 43 'of a device

That is having no DC power source of the type shown at 45 but otherwise identical to the device of FIG. 3. The discharge of the previously evenly charged insulating surface of the paper sheet 1 ^! takes place by gradual scanning in parallel rows, since after prior connection of the high-frequency oscillator 44 ¹ with the electrode 43 ', one side of the electret 47 is first placed on this electrode, which is then gradually covered by the electret thanks to a continuous deformation movement of the same, which causes its discharge in successive parallel rows when these rows touch the electrode 43 '.

The device of Fig. 5 has a reserve of photoconductive paper which is in the form of a coil 26 is located on a mandrel 27. This paper advances in the direction of the arrow, initially running under a charging station 20 (the Scorotron type), the conductor 1ya of which is caused by the high voltage source 19b is brought to a voltage of 3500 to 12000 volts with respect to the grounded jacket 19c. The paper loaded in this way 2 comes in front of an exposure station with a lens 29 and lighting

BATH ORIGINAL

_ 21 -

processing devices 24 and 25, in front of which the original 30 passes in the direction opposite to the movement of the paper 2. After passing over the rotating drum 3, v / o / it is brought opposite a paper 1, which is passed through the rotating drum under the conditions referred to with reference to I ¹ Ig. 1 is driven, the paper 2 is subjected to uniform illumination by a light source 23 in order to destroy and dissipate the remanent charges of its photoconductive layer, whereupon it is wound onto a mandrel 28. Me reproductions are made on the paper 1, the insulating surface of which has been previously charged by the scorotron type charging station 22, | whose conductor 21a is brought to high voltage with respect to earth by a high voltage source 21b. After the paper in the reel 26 has been exhausted, e.g. after about a hundred copies have been made on office paper of the format 21 χ 27, the reel 33, on which the entirety of the paper 2 is now wound, is replaced by the reel 26 by interchanging the mandrels 27 and 28 brought, or the paper 2 is rewound against its unwinding direction by means of the drum 3, care being taken that the formation of reproductions at the location of the drums 3 and 4 is avoided, which for this purpose during this backwashing by a control device, not shown can be spread apart. If the reel 26 initially has a paper reserve 2 of 60 meters, about two hundred reproductions in the format 21 × 27 can be produced.

The in Fig. ' 6 illustrated device of the The scorotron type is that in the device of FIG. 5 "at 20 or used at 22 it has a metal jacket 21c in the form of an incomplete earthed cylinder with a diameter of the order of 20 cm and an axial conductor 21a,

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which is formed by a tungsten wire 80 microns in diameter and is brought to a potential of several thousand volts by the voltage source 21b. The jacket 21c is through a part of insulating material 21d provided with a mask is extended, which plays an essential role in establishing the uniformity of the pre-charge of the photoconductive paper or paper plays on which the playback takes place. It is assumed that this part 21d forms a barrier for ions that are too fast, which move in the direction of the surface of these papers, which prevents any overloading of the same. Simultaneously forms this part a trap for any individual ions with a mark which corresponds to that of the ions generated within the shell 21c is opposite, these former ions being captured and / or neutralized by this part. This part owns preferably a small mass per surface unit, so that it then forms a veil, which is expediently made of plastic e.g. polyethylene terephthalate ("Mylar") or nylon · It is believed that this barrier effect is achieved by the cargo which this part assumes in the presence of oxygen ions in the surrounding air. The number of meshes of the Veil is preferably three to four per linear millimeter.

The device of FIG. 7 enables the method to be carried out completely continuously. It is derived directly from the device of FIG. 5, so that identical parts of these two figures are denoted by the same reference numerals. The base of the photoconductive layer is formed here by an endless belt 48. To regenerate this photoconductive layer in order to carry out a new playback , the endless belt 48 first runs in front of the light source 23

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for the removal of the remanent charges and then in front of the stations

31 and 32, showing the sensitivity of the photoconductive layer to allow for quick rewinding of the belt restore in the working process · The station 31 is a heat source, preferably a source of infrared rays, and

32 a charging station of the scorotron type, which _{is modified in the manner described under B e with} reference to FIG. 6, the high voltage source of this work station having the opposite polarity as the sources 19b and 21b.

In the device of FIG. 8, the photo | conductive layer of the endless belt 49 arranged parallel to the paper 1 over a distance which is the distance between the two Pairs 5Oa-50b and 51a-51b of rotating rollers. The electric field with high frequency component is made by means of conductive grids 35 and 36 with loosely rotatable on their axes Rods fed, the grids being carried by the metal housings 37 and 38, respectively, in which a negative air pressure is generated is to the endless belt 49 or the paper ji against the grid Press 35 or 36. To clarify the figure, the workplaces for loading the endless belt and paper are and the optical system for projecting the motif of the original to be reproduced is not shown, as is the Regenerating stations, which the endless belt 49 after production of the reproductions.

Those formed on the paper 1 of Figs latent images are developed and fixed in the manner known per se in xerography.

Regarding the formation of the endless belt 48 (Fig. 7) or 49 (Fig. 8) it should be noted that there are few

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at least two layers, namely a first lower one Layer made of a suitable material, which gives it the physical properties necessary for the high number of successive passes during the withdrawal of a large ' Number of copies are required, and an upper photoconductive layer. Said material can be natural or synthetic Be rubber, which contains suitable additives, which determine its degree of elasticity, and / or additives, which make it more or less conductive (e.g. through the incomplete Soot produced by the combustion of luminous oil). The used Rubber is e.g. a butyl rubber (Esso) or a silicone elastomer. This material can also be a plastic, e.g. a copolymer of vinyl chloride and butadiene, a copolymer of butadiene and Stjeen, a copolymer of vinylidene chloride and acrylonitrile, a polyester polyvinyl butyral, pliolite 3,4, 5 or 6 etc. The photoconductive layer contains a photoconductor, such as zinc oxide, dispersed in an insulating synthetic resin. with sensitizers for panchromatic reproduction, such as ζ · Β. Acridine orange, fluorescein, eosin, rose bengal and methylene blue. The top layer can also be cadmium sulfide as a single photoconductor or as a photoconductor combined with the zinc oxide contain, or cadmium sulfide doped with manganese and oxygen to achieve a good sensitivity. The photoconductive Layer can also contain organic photoconductors, such as anthracene, Triazoles, oxaziles, thiazoles and triazines. This layer can have any inherent color without having a negative impact on the quality of the reproductions own. The paper 1 is preferably a common paper, which weighs about 40 to 70 g / m and a thin insulating

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'has a layer, which is e.g. or calcium or aluminum is formed, which in a binder is dispersed, such as Methylpolymethakrytefc, a copolymer of butadiene and styrene, a copolymer of vinylidene chloride and acrylonitrile, butyl rubber, etc.

1098 15/1626

Claims (1)

- 26 patent claims Ί 772456 1. ) L method for photoelectric reproduction, characterized in that, starting from an original (30) to be reproduced, an electrostatic image is formed on a photoconductive surface (2) carried by a base that conducts static electricity, that a non-photosensitive and non-photoconductive insulating surface (1a) of a sheet of paper (1) or the like. is evenly charged with static electricity, whereupon in the dark this photoconductive surface (2) is brought into contact with the insulating surface or in the immediate vicinity thereof, the zone (14) into which these two surfaces are brought in this way, the Effect of an electric field is exposed, which has a high frequency component and a DC component, whereupon in a known manner after separation of the photoconductive surface from the paper sheet, the electrostatic image formed on the insulating surface of this paper sheet is developed and fixed. . 2 ·) Method according to claim 1, characterized by the use of an electric field, its high-frequency component corresponds to a frequency between 1.2 kHz and 3000 MHz. 3.) Terfahren according to claim 1, characterized in that when the zone (H) is in the air, the Gross component amounts to at least a few tens of volts on a large scale. 4.) The method according to claim 1, characterized 109815/1626 draws that the constant component through a with a conductive Base of the paper sheet connected direct current source (10) is generated. 5.) Method according to claim 1, characterized in that that the equilibrium component by induction by means of a generated in the vicinity of the zone (14) brought electrets (47) will. • 6 ·) Method according to claim 1, characterized in that the electrostatic image is reversed * . ■■■■■ ' Is the image of the original to be played back. I. 7.) The method according to claim 1, characterized in that that the insulating surface (1a) of the paper sheet (1) is evenly charged by giving a space charge owning apparatus (22), e.g. a scorotron will. . 8.) The method according to claim 7, characterized by the use of a modified scorotron (22), the the part opposite the insulating surface (1a) one the passage of the charges to the insulating surface uniform surface (-21 d) is formed. ' 9.) Method according to claim 1, characterized in that that the insulating surface (1a) is negatively charged. 10.) The method according to claim 1, characterized in that that the insulating surface (1a) is positively charged. · 11.) The method according to claim 1, characterized in that that the electrostatic image after uniform charging of the photoconductive surface (2) by optical means is obtained. 10 98 1 J / 1U2 6 -electrostatic forms. 17.) "Device according to claim 16, characterized characterized in that the drive devices by two rotating Drums (3, 4) with parallel axes and the same peripheral speeds are formed. 18.) Device according to claim 16, characterized in that that the drive devices (50a, 50b, 51a, 51b) are designed so that the fixed zone (H) in which the two surfaces are kept in mutual contact or in close proximity to one another, proportionally is extended. 19.) Device according to claim 18, characterized in that the drive devices by two pairs of rotating drums (50a, 50b and 51a, 51b) are formed, which are spaced apart from each other by such a distance that the fixed Zone (14) in which the two surfaces (2, 1a) are held in mutual contact or in direct mutual proximity are relatively expanded and equal to the distance between these two pairs, the peripheral speeds of the rotating drums all the same and in the sense of these fixed ( Zone are directed. 20.) Device according to claim 16, characterized characterized in that the devices (9, 10, 47) for generating the high-frequency alternating component are a high-frequency oscillator (9) included. 21.) Device according to claim 16, characterized in that that the devices (9, 10) for generating the constant component contain a direct current source (10). 22.) Device according to claim 16, characterized 109815/1626 _Λ 12 ») Method according to claim! by using a photoconductive surface (2) Zinc oxide base. 13 ·) Method according to claim 12, characterized in that that the acid oxide of the photoconductive surface is activated by adding these panchromatic substances, 14.) "Method according to claim 12," characterized in that that the photoconductive surface (2) is based on zinc oxide evenly before the formation of the electrostatic image is charged negatively. 15.) The method according to claim 1, characterized in that that the distance between the two surfaces (2 and 1a) is between 0 and 120 microns. 16.) Gate direction for continuous exercise of the method according to one of claims 1 to 15 » by means (24, 25, 29) »which are to be reproduced by one Original (30) an electrostatic image on a photoconductive Surface (2, drive devices (3 »4; 50a, 50b} 51a, 51b; 35 »36), which at the same speeds this photoconductive surface (2) and a paper sheet (1) o. The like. With an insulating surface (1a) on which the electrostatic image should be reproduced in mutual Bringing them into contact with or in immediate mutual proximity in a fixed zone (14) of the device, devices (9, 10), which in this zone (14) an electric field with a discontinuous Generate high frequency component and a constant component, and facilities for development and fixation that formed on the insulating surface of the paper sheet 10 9 8 15/1626 ^ ₀ original holds. characterized in that the devices for generating the constant component by forming an electret (47). 23.) "Device according to claim 16, 20 and 21, characterized in that the one! rammel (4) through a conductive chain with the common point of the high frequency oscillator (9) containing high-frequency circuit and the DC source containing the DC circuit (10) connected while the other drum (3) is grounded. 24.) Device according to claim 23 »characterized in that that the high-frequency circuit develops a resistance 25.) Device according to claim 23 »characterized in that that the high-frequency circuit contains a capacitor (18). 26,) Device according to claim 23, characterized characterized in that a system (8, 13) for stabilizing the potential between said common point and earth is arranged. 27.) Device according to claim 26, characterized in that the stabilizing system is one with a resistance (13) series-connected neon lamp (S). 28.) Device according to claim 16, characterized by two coils (26, 33), one of which is moving upward arranged a coil (26) for feeding a paper (2) or the like. which forms the photoconductive surface carries, while the other downstream spool (33) for winding the same paper after passage through said zone (14) is used. 29) Device according to claim 16, marked 109815/1626 . ■ - 3 net o by an endless B _a nd (48), soft through a paper. like. is formed (2) or such it carries out, comprising the photoconductive surface, the path of this endless belt by the said solid zone (14). 30.) Device according to claim 18 and 19 »öa- characterized in that fixed »formed by rotating files Grid (35, 36) on the back of the photoconductive top " surface of supporting paper ο «like. and on the back of the insulating surface of supporting paper ο »like. are arranged where * one of these sitters through a conductive chain with the ge | common point of the high-frequency circuit (9) and the direct current circuit (1 "O) is connected while the other grid is grounded is. 31.) Door direction according to claim 30, characterized by devices (37 »38), which in particular with a Work suction and press the papers against their grids «, 32.) Device according to claim 16, marked by means (20), which immediately before the formation of the electrostatic image, the photoconductive surface is uniform charge. ' 33.) Device according to claim 32, characterized in that it has downward movement devices (20) for uniform charging of the photoconductive surface and upward movement of the fixed zone (14) has devices (24, 25 »29) which the image of the original to be reproduced (30) optically * on the evenly charged photoconductive surface (2) project to the electrostatic image on this photoconductive To generate surface. 34.) Device according to claim 32, characterized'-ge " 1098 15/1626 BAD ORlGINAU indicates that it is moving downward from. the fixed zone (14) or upstream of the devices (20) which evenly charge the surface on the side of the phoito, has erasing devices (25 »31» 32) for erasing the electrostatic image of the photoconductive surface. 35.) Device according to claim 34 »thereby characterized in that the erasing devices by a point (23) for exposing the photoconductive surface with a uniform light can be formed <> 36.) Device according to claim 34 »characterized in that that the erasing devices through a point (31) for exposing the photfcleitenden surface with a Infrared radiation is formed. 37.) Device according to claim 34 »characterized in that that the extinguishing equipment. (32) are designed so that they coincide with the photoconductive surface charge a charge whose sign is opposite to that which this surface immediately before the formation of the electrostatic Picture must be granted 38.) Device according to claim 16, 32 and 37 » ά a characterized by the fact that the devices (20, 22, 32) for uniform charging of the surface have a device of the scorotron type working with glow discharge. 39.) Device according to claim 38, characterized in that the discharge device (20, 22, 32) a the insulating surface of the paper sheet or the photoconductive one Has the opposite surface section, which by a Τ ·· -ΐ1 (21d) for the uniformity of the Transfer of charges to the surface in question (1 or 2) 10 9 8 15/1626 BATH ORIGINAL . is formed. - ■ 40.) Device according to claim 39 »thereby being · indicates that the uneven part (21d) is formed by a veil of insulating material «, 41.) Opaque, transparent or translucent paper or the like. to form one with those in the Xerography customary process developable electrostatic image, characterized in that it is on at least one side has an insulating layer, ao that it has at least one insulating outer surface, | 42.) Paper according to claim 41 »characterized in that the insulating layer by a dispersion of a insulating substance is formed in a suitable binder. 43o) paper according to claim 42, characterized in that that the insulating substance by calciunistearate and the binder is formed by methyl polymethacrylate. 44.) Endless belt with photoconductive surface, characterized in that it is a base of a flexible, resistant material, which optionally contains fillers, and has at least one outer photoconductive layer. 45.) Endless belt according to claim 44, characterized characterized in that the outer photoconductive layer has an in containing an insulating resin dispersing photoconductor. 46.) Endless belt according to claim 44 »thereby marked that the base is a plastic or a natural one or artificial rubber. 47.) Endless belt according to claim. 46, thereby 109815/1626 indicated that the plastic is selected from the following substances: copolymers of vinyl chloride and butadiene,
Copolymers of butadiene and styrene, copolymers
made of vinylidene chloride and acrylonitrile, polyester polyvinyl butyral, Pliolite 3 to 6 etc. *. 4 & *) Endless belt according to AnsOrueh 44, characterized in that the inner layer has a sensitizer
for panchromatic reproduction. 49 ·) Endless belt according to claim 48, characterized marked that the sensitizer under the following compounds selected is: acridine orange, fluorescein, eosin, rose bengal, Methylene blue. 50.) Endless belt according to Ansprudfc 45, thereby characterized in that the photoconductor is selected from at least one of the following compounds: zinc oxide »! cadmium sulfide, Anthracene, Triazole, Axacile, Thiazole, Triazine etc .. 51.) Endless B _a nd according to claim 45 'characterized characterized in that the photoconductor with manganese and / or oxygen is endowed. 10 9815/1626 Blank page