DE2530290A1 - Xerographic copying - producing multiple copies from a single latent charge image - Google Patents

Abstract

Xerographic copying is carried out by (a) impressing in imagewise manner an external electrical field or a mechanical force no a ferro electric or induced ferroelectric material, the ferroelectric polarisation of which can be intensified by such field or force and thereby product an image from ferroelectric polarisation pattern on the surface of the material. (b) producing a change of an external electric field, a mechanical force or a heating for the temporary changing of the intensity of the ferroelectric polarisation, in order to produce an image form charge pattern on the surface of the material corresponding to the ferroelectric polarisation pattern such that a toner pattern is produced by adsorption of toner on the charge pattern. (c) transferring the toner image so obtained to a copy carrier. The process enables a large number of toner images to be produced directly from electrical signals via a single latent charge image, which itself may be produced from electrical signals without an original print out.

Description

Method and apparatus for copying The invention relates to a Method and apparatus for printing and copying.

In particular, the invention relates to a xerographic copying process, in which an electrostatic latent image is first generated, this into a toner image converted and then transferred the toner image from the intermediate carrier to the copy carrier will.

The process of electrophotography is used in various areas used, especially in copiers of various kinds. These methods are commonly summarized under the term xerographic process ".

In xerography, the surface of a photoconductive film becomes Electrically homogeneously charged in the dark. An image will appear on the charged surface focused. The specific electrical resistance is in the bright areas of the image the photoconductive surface is lowered. The surface charge is compensated and dismantled. The dark areas of the image, on the other hand, remain electrically charged. On the photoconductive surface is thus a charge distribution obtain, which corresponds to the gradation of the image to be applied. On the photoconductive So a latent electrical image is generated on the surface, its gradation and Corresponds to the brightness of the original. The latent image is not visible to the naked eye recognizable, but can be achieved by applying the finest colored resin particles, which are commonly used as n toner "can be made visible. When the toner is applied the toner particles adhere to the surface bearing the latent image Effect of Coulomb forces on the electrically charged areas of the surface. The latent image is developed in this way.

Depending on the polarity of the toner used for development a positive-positive development or a positive-negative development can be brought about.

After the latent electrical image is developed, the Toner image placed on a copy carrier sheet. The arrangement obtained is again from the back of the copy medium, usually a sheet of paper, by a corona discharge electrically charged. When the copy carrier is peeled off, the toner becomes photoconductive Transfer the surface to the surface of the copy medium. During the subsequent Heating the copy carrier, for example by exposure to IR rays, melts the resin of the toner and fixes the image on the surface. The copying process is over with that. The one remaining on the photoconductive surface after this process Toner is brushed off and used again.

The xerographic paper process has established itself in office practice can and is one of the most important methods of copying documents today and images. More recently, in particular, methods for making xerographic Color copies became known.

It is very rare that only one copy is made of a template. As a rule, there are several, not infrequently many, copies of an inserted original required, for example for the production of catalogs or conference documents.

When using the traditional xerographic process from an original If several copies are to be made, a Reproduction of the template can be made. This makes copying performance sensitive decreased. It will take a relatively long time for a given number of copies needed. This is because the electrostatic latent image on the surface of the photoconductive material after each copy transfer step get lost.

With a typewriter, a teleprinter or a typist Data terminal can be converted by converting electrical signals in a direct way Plain texts are received. In a corresponding application of this direct plain text generation it is also quite desirable to have numbers, letters, patterns or graduated images similarly by directly converting electrical signals into copyable Lay down form. However, according to the common xerographic method, this is the case only possible if the electrical signals are initially used in a conventional manner, for example via a writing machine, and this picture is written down is then used as a template for making the copies. Image content with gradation cannot be implemented in such a way that they can be copied at all.

Of course, a raster image could be replaced by one known per se Printer, for example a dot printer from electrical signals built will. As a dot printer could for example be a dot matrix printer are used whose pressure peaks are mechanically activated by electrical signals will. The response time of the print wires — however, is known even in the fastest Printers of this type are limited due to mechanical inertia. This is how it is, for example It is not possible to use this method to convert a recorded video signal to a television picture for example on a sheet of paper.

It is a primary object of the invention, in light of this state of the art Technique to create a xerographic copying process in which the latent electrical Image is not erased even if the toner transfer is repeated many times, so that repeated the desired number of copies of one and the same latent image Toner development can be obtained; The main aim of the invention is therefore in particular the creation of a xerographic copying process in which the latent image is stable can be saved.

Another object of the invention is to provide a xerographic Copying process in which the latent electrical image is directly replaced by electrical Image signals can be generated without prior production of a plain text original and then produced directly from electrical image signals latent image any number of copies can be produced by repeated toner development are.

Another object of the invention is to provide a xerographic Copying process with which high-frequency electrical image signals, for example Video signals, can be printed out.

Finally, another object of the invention is to provide a Copy intermediate carrier or a printing form to carry out the previously outlined Copying process.

The invention is therefore based on the object of a xerographic To create copying and printing processes that allow the production of any number of prints of one and the same latent electrical or electrostatic image on the Copy intermediate carrier enables practically unlimited storage of the latent Image enables the direct creation of the latent electrical image allows electrical image signals and at the same time such a high recording speed allows high-frequency electrical image signals, such as video signals are printable. Another object of the invention is to provide an intermediate copy carrier, thus a carrier for generating and storing the latent electrical image to accomplish.

To solve this problem, a copying process is proposed, which according to the invention is characterized in that (a) a ferroelectric or an induced ferroelectric material, its ferroelectric polarization under the influence of an external electric field or a mechanical force be intensified, image-wise an external electric field or a mechanical one Force impresses and thus an imagewise ferroelectric on the surface of the material Polarization pattern creates1 that one (b) a change in the material external electrical field, mechanical force or heat Change in the strength of the ferroelectric polarization generated so on the material surface an image-wise charge pattern corresponding to the pattern of ferroelectric polarization to produce a toner pattern by adsorbing a toner on the charge pattern and that (c) the toner image thus obtained is transferred to a copy carrier.

In summary, the invention thus creates a method to the Copying or printing two-dimensional images where one is two-dimensional image-wise distribution pattern of an external electric field on the surface a thin ferroelectric disc. This is done on the surface of this thin ferroelectric disk creates an image-wise polarization pattern, fixed and saved. By the action of heat on the thin disc pretreated in this way The degree of polarization in the ferroelectric changes and is on the surface of the plate builds up an electrical charge pattern that corresponds to the polarization pattern is equivalent to.

On the image-wise electrically charged surface of the disk a toner applied. This creates a toner image1 that corresponds to the induced charge pattern is equivalent to. The toner image is then transferred to a copy medium. According to the usual xerographic copying can be done from any latent electrical image respectively only a single print can be made. In contrast to this, according to the invention produced latent image numerous copies can be made. In addition, for Carrying out the known copying process in any case a template1 often also referred to as "original" is required. In contrast, according to the procedure of the invention can be copied from a template, but is for production Such a template is not necessarily required for prints. Rather, can electrical image signals or electrical signal patterns directly into a latent image are implemented, on which the toner images can then be developed.

An external electric field is preferably used to generate the latent image. In the same way, however, the action of a mechanical force can also be used for this purpose. The electric field or the force field are visually impressed on a material which, under the action of these fields, reinforces a stable ferroelectric polarization also referred to as "ferroelectric" for short. By the action of the electrical or mechanical field on the surface of such a field-reinforced ferroelectric material, a ferroelectric polarization pattern is generated in it, which corresponds to the pattern or image of the acting field. The ferroelectric is then exposed to the action of a homogeneous external electric field, a homogeneous mechanical force or a homogeneous heat field, whereby the degree of ferroelectric polarization is temporarily changed.A toner is adsorbed on the charge pattern thus generated, which depicts the ferroelectric polarization pattern. The resulting toner image is transferred to the copy medium, usually a sheet of paper.

A printing forme or is preferably used to carry out the method a copy intermediate carrier is used, which according to the invention is a thin disk or Plate is made of a field-reinforced ferroelectric material and on one of its Surfaces wearing a photoconductive coating.

A first electrode is arranged on the back of this thin disk. A second electrode is applied to the photoconductive coating. At least one of the two electrodes is designed to be removable. The electrode through the rays must pass through or through which an image is to be focused of course be made transparent. The removable electrode can for example in the form of an electrically conductive viscous liquid as a liquid electrode be upset. Such a liquid electrode can for example be produced in the manner be that one the electrically conductive viscous liquid on the surface of the thin ferroelectric and applies to this liquid layer with a a transparent thin-film electrode coated glass plate applies. (Nesa glass) When on the photoconductive surface of such as a printing form or copy intermediate structure to be designated an optical image focuses and at the same time an electrical voltage is applied to the two electrodes of the structure is applied, in this way an electrical change is made to the ferroelectric imprinted on the image-wise light-dark distribution of the on the surface of the Ferroelectric corresponds to the focused image. By doing that in this way image-wise imprinting of an external electric field pattern on the ferroelectric This material is partially polarized in terms of image. The image is so called latent electrical image stored in the field-enhanced ferroelectric. This process is called "fixing" the image.

After defining the latent electrical image as specified An electrode is removed from the template from the ferroelectric to create a shield to prevent the electrical lines of force caused by polarization. To further rule out a shielding effect due to surface charges, the ferroelectric freed from one of the electrodes becomes electrically insulating Atmosphere heated. This is the strength of the remanent ferroelectric polarization and the balance between the size of the ferroelectric polarization and the surface charge so that a corresponding to the latent image Pyroelectric charging meter is created. Instead of heating can be used for this purpose cooling can also be carried out.

Then the surface of the so freed from the electrode treated ferroelectric brought into contact with a toner, so that a visible toner image is produced. This toner image is then transferred to a copy medium transferred and then fixed. The copy medium then has a true-to-original image of the original, whose Image on the surface of the ferroelectric or the material 5, which is ferroelectrically induced under the action of a field, is focused became. The toner remaining on the copy intermediate carrier can then be wiped off or brushed off.

The cleaned copy intermediate carrier is redeveloped with toner, and the toner image restored in this way can be used again on the next copy carrier transferred and fixed there. In this way, the stages of development of the toner image and the transfer of the toner image from the copy intermediate carrier the copy medium can be repeated in accordance with the required deductions.

The latent image can be on the copy intermediate carrier or on the printing form but also without the help of a template and its focus on the surface the printing form can be obtained. For example, the surface of the printing form with a finely focused, strong light beam, for example a laser beam, are scanned, this light beam in a known manner, for example line by line across the screen and can be modulated accordingly. The deflection and modulation can be purely electrical by means of electrical image signals being controlled. The latent image created in this way will not pass through a plain text template, but exclusively through electrical information signals generated.

After the focusing method described first, the electrical Charge modulated by the intensity of the light while following the second method the inscribing, the latent image defining intensity of the light or the The light beam is modulated directly and exclusively by an electrical voltage will. The areas irradiated in this way can then, for example with an electrical voltage can be scanned. Using both of the methods described above a ferroelectric and a photoconductive film are used in combination.

Such a structure will be referred to as an FE / PC structure for short in the following. In this sense, the invention relates not only to the mere use of FE / PC structures to define latent images, but also to the use of cf ~ rC> C * f aolshen ms / rc / r <- structures for the definition of latent images using exclusively electrical signals as image information without scanning by light beams and subsequent printing of these FE / PC structures.

In this latter case, the sampling takes place instead of how previously described, with a laser beam with an electron beam. Depending on the type Copy intermediate carriers can also be used to generate the latent electrical image or printing forms of the most varied of training for carrying out the process of the invention can be used. When creating the latent image from electrical Signals without the aid of optical beams are preferably used as a carrier for the latent image is used, which consists of a ferroelectric to sense aforementioned and the surface of which is covered in a matrix-like manner with row and column electrodes.

The electrodes are on a common surface of the printing form Applied in such a way that, despite the matrix-like arrangement, their electrical Isolation from each other is guaranteed. On the opposite side of the Ferroelectrics are at the points that the crossing points of the column electrodes and the row electrodes correspond to individual electrical elements in the manner of raster points applied electrodes isolated from each other. If you now put it on one of the row electrodes and at one of the column electrodes of this structure a so-called half-value voltage, thus a voltage ** half as large as that for the polarization of the ferro-elite tricam required voltage, so will the s ferroelectric in that area below the intersection of the row electrode and the column electrode ferroelectrically polarized. By successive selective control of a In this way, the sequence of raster points in the ferroelectric can produce a ferroelextric Polarization pattern can be built up like a grid, the information electrical Represents signals in the image grid. If a ferroelectric that works in this way a polarization pattern has been impressed by an external electric field, is heated in an electrically insulating atmosphere and in the previously described Wise treatment can also be done by direct conversion of electrical signals receive a directly readable print or a copy of the electrical information will.

Instead of a printing form of the structure described above, a The printing form used has row electrodes on one side and row electrodes on the opposite Side carries the column electrodes. In this design, either the row electrodes or the column electrodes are made detachable. Furthermore, the printing form can be so be designed so that they have electrodes on one surface in the pattern of the 7-segment display and on the opposite surface an electrode carries the entire Evenly covered surface of the ferroelectric.

When using a transparent ferroelectric, its optical Properties are a function of the ferroelectric polarization state, can the latent image can also be made directly visible. Through direct observation The latent electrical image can also be projected onto a projection surface already during the creation with regard to its information content and / or or his Quality to be checked. The picture can also be deleted and corrected. In this way, latent images are high quality and hence Prints or copies can be produced, which also have a high image quality and are free of errors in terms of content.

After making the desired number of prints from a latent Image that is no longer required can be deleted. The printing form is then available for a new definition of another latent image. The deleting of the latent image can be done in a simple way in such a way that the printing form heated to a temperature above the phase transition temperature, in which the material changes from the ferroelectric state to the paraelectric state transforms. Either the electrodes are short-circuited or an opposing voltage is applied created. Instead of heating the printing form and short-circuiting the electrodes, it is sufficient In many cases, however, it is already possible to simply immerse the printing form in hot water. However, after each of these processes it is possible to do this once on a printing form partially or completely erase the recorded latent image. The phase transition temperature is, for example, 110 ° C for 7/65/35-PLZT, 50 ° C for 7,6 / 70/30-PLZT and for 7.9 / 70/30-PLZT at 25 ° C. PLZT stands for "for" lead-lanthanum-zirconate titanate ".

The first of the three indicators gives the multiplied by a factor of 100 The number of moles of lanthanum contained in each formula unit is the second number the number of moles of the zirconium contained in each formula unit, multiplied by a factor of 100 and accordingly the third number is the number of moles multiplied by a factor of 100 of the titanium contained per formula unit, whereby the spaces in the sublattice of the tetravalent cations are not taken into account.

When heated to erase a latent sEebling on a printing form Image, the temperature to which it is heated is preferably chosen so that no space charge remains on the surface of the printing form. The for this in individual cases required temperature depends on the type of ferroelectric and can be Can be readily determined by those skilled in the art.

As ferroelectric materials in which a stable ferroelectric State of polarization under the influence of an external electric field or a mechanical 'field can be generated or reinforced, are the following materials called: BaTiO3 single crystals, TGS single crystals (TGS = triglycine sulfate), ceramic Materials such as BaTiO3, Pb (Zr, Ti) 03 and (K, Na) NbO3 and transparent ceramic materials of the system PbLa (Zr, Ti) 03. All of the aforementioned materials are Ferroelectrics in the narrower sense.

However, they are also suitable as a material for the printing form of the invention those substances in which both the ferroelectric state and the antiferroelectric State coexistent or non-ferroelectric materials in which the ferroelectric State can be generated by impressing an electric field, for example solid solutions of various systems of the Pb (Zr, Ti) 03 series, in particular (Pb, Sr) (Zr, Sn, Ti) 03, (Pb, Sr) (Zr, SnTi) Nb03 and (Pb, Ba) (Zr, Hf, Ti) O3 as well as clear ceramic materials, such as in particular (Pb, La) (ZrTi) O3, (Pb, Sr, Ba) (Zr, Ti) 03 and (Pb, La, Sm) (Zr, Ti) 03. In contrast, ferroelectrics, in which only strip-shaped Area structures can be generated so ferroelectrics, such as Gd (MoO4) 3 and potassium sodium tartrate, as materials for the printing form of the invention not suitable. Ferroelectric polarization cannot be used in these materials can be generated imagewiseJ as material for the photoconductive film or the photoconductive film The following materials are named: compositions, the by incorporating sensitizers into organic materials, for example by incorporation in polyvinyl carbazole, and inorganic substances, such as in particular CdS, CdSe, ZnS, ZnSe, Se and ZnO.

The specification conditions depend on the type of material for the photoconductive layer. The type of bonding of the photoelectric layer also matters on the ferroelectric in the setting parameters. For example CdSe and similar salts, preferably for PZT ceramics (PZT = lead zirconate titanate) and photoconductors based on polyvinyl carbazole for monocrystalline ferroelectrics, especially used for TGS single crystals.

These different behaviors of the photoconductive materials on certain ferroelectrics is evident on the intensity of the saturation polarization and the coercive field of the respective ferroelectric and the bond conditions between the two materials.

When using transparent electrodes, these are for example by depositing solid solutions of In203 * SnO2 by cathode sputtering Vapor deposition in a vacuum of In203, Sn02, Ti02 or ZrO2 or by spraying so-called Nesa layers made. Such Nesa layers are transparent thin-film electrodes, which are obtained in such a way that one at higher temperatures on the to be coated The surface is sprayed with aqueous Sncl4 solutions, for example with Sb or Bi are endowed. Good results are obtained especially when using the aforementioned transparent thin-film electrodes achieved. Nevertheless, it can also be used for numerous Purposes of use opaque electrodes are used, for example in Vacuum deposited metal layers, electrolessly deposited metal coatings, in particular silver mirrors, or painted metal pastes.

For the production of the liquid electrodes described above, you can almost all electrically conductive viscous liquids are used on that the ferroelectric has no negative influence. Examples are Glycerin based fluids or viscous fluids called as conductivity salts LiCl1 contain NaCl or KC1. The liquid is preferably as thin as possible applied to the surface to be coated to prevent bubble entrapment.

The invention is illustrated in the following on the basis of exemplary embodiments Connection with the drawings described in more detail. They show: FIG. 1 in plan view and in a side view of an embodiment of the printing form of the invention for image recording; Fig. 2 in plan view and in side view of a modified embodiment of the printing form shown in Fig. 1; 3 shows the production in a schematic representation a toner image according to an embodiment of the invention; 4 in plan view from the Oberseitepnd the underside and in side view of a printing form of the invention for processing electrical raster signals; Fig. 5 is a partial representation the printing form shown in FIG. 4; FIG. 6a shows a circuit 1 that of that shown in FIG Printing form is equivalent; FIG. 6b shows a partial representation of that shown in FIG. 6a A circuit showing a unit of this circuit; Figures 7a and 7b another Embodiment of the printing form of the invention for processing electrical information signals; FIGS. 8a and 8b show a further exemplary embodiment in a plan view and a side view the printing form of the invention for digit processing by electrical signal control and Fig. 9 in plan view and in side view of a further embodiment Production of a toner image using the method of the invention.

In the following, an FE / PC structure is first described, which the The main element of a printing form of the invention is that for processing by light rays is used on embossed images.

The FE / PC element is a four-layer structure. A thin slice of the ferroelectric is on one of its surfaces Completely covered with an electrode The opposite side of the ferroelectric is coated with a photoconductive material (PC). The surface of the photoconductive The coating is covered with a transparent thin-film electrode. On the surface of the photoconductive coating, an image is optically focused. At the same time will DC voltage is applied to the two electrodes, hereinafter referred to as "writing voltage" for short. is designated. The is in the light areas on the photoconductive surface specific electrical resistance of the photoconductive coating is low. The writing tension therefore acts mainly on those areas of the ferroelectric that are under the bright image areas of the photoconductive coating.

The electrical resistivity of the photoconductive coating at the same time in the dark picture areas.

The writing voltage is applied to the photoconductive coating Component and divided into a voltage component lying on the ferrous electric. So only a part of the applied writing voltage acts on the ferroelectrics.

In this way, a ferroelectric is in the ferroelectric Polarization induced only in those areas that correspond to the bright areas of the image. The polarization indicated in this way in the ferroelectric remains even then obtained when the voltage applied to the electrodes is reduced to zero and the electrodes are short-circuited. Also remains after the writing voltage is released the polarization generated in the thin disk of the ferroelectric even then obtained when the ferroelectric is exposed. So the picture of the original is Stably stored in the ferroelectric in the form of a polarization pattern. With others In the FE / PC element described above, words can be used to represent a template inscribed in the form of a latent electrical image and saved The FE / PC image storage element is preferably transparent and has optical Properties that are dependent on the direction of polarization, with this in particular the refractive index, the absorption in the visible range and the scattering come into question in the visible area. In such an FE / PC element the latent electrical image stored in the form of a polarization reversal. Therefore, the registered latent image can be observed directly, either by using a polarizer or by viewing under parallel light.

However, since the Fe / PC element is sandwiched between two electrodes is the electric field of the polarization pattern that corresponds to the latent electric Image corresponds, shielded by the electrodes. The latent image is in this one State of the FE / PC element does not develop even if it is with toner is brought into contact.

If toner development is not required and transfer of the image is not needed, for example to correct or check the generated latent image, no further action needs to be taken at this stage of the process because the latent image is visible and can be viewed. For the However, the production of prints is a toner development and the transfer of the Toner image on the copy carrier required.

For the development of the latent image with a toner at least one must one of the electrodes that shield the polarization field lines can be removed. However, since the electric latent image is in the form of a polarization pattern in a Ferroelectrics are stored, the electrodes can be safely removed, without affecting the quality or stability of the image. That FE / PC element which can be used for the method of the invention is therefore used the storage of a latent electrical image, the reproduction of an original serves. The inscribed latent electrical image is therefore not absolutely necessary to be visualized with the toner before development.

It can therefore be used for the production of such printing forms practically any any ferroelectric can be used, as long as this is done in the manner described is capable of capturing and storing a latent electrical image.

In particular, the ferroelectric used only for copying purposes needs of a printing form neither to be transparent nor to have optical characteristics, which depend on the direction of polarization. It can be both single crystals and Ceramics are used. Practically everyone can only use it for copying any ferroelectrics can be used with only the above limitation is to be observed.

Such a ferroelectric is in the manner described with a photoconductive coating provided. The FE / PC element obtained is on his both main surfaces provided with electrodes, whereby a four-layer structure is obtained. Of these two electrodes, at least the one on the is preferably Side of the photoconductive coating applied electrode transparent. The opposite Electrode can also be opaque. One of the two electrodes is fixed with connected to the surface of the element, while the other is designed to be removable. It is preferably designed so that, with the interposition of an electrical highly conductive liquid material is bound to the surface of the FE / PC element and can therefore easily be lifted off again. Also in the FE / PC element constructed in this way can in the manner described above, the image of an original in the form of a latent electrical image can be saved.

To develop the toner image on such an electric latent The detachable electrode is then removed from the structure in order to image first not to shield the electric field of the polarization pattern. Even if the Electrode is lifted and the surface of the ferroelectric carefully from the Electrically conductive liquid was released, can be on the exposed surface the printing form storing the latent image is not yet able to obtain a toner image. The reason for this lies in the generated by the electrically conductive liquid Charge that is still adsorbed on the ferroelectric as a surface charge and that Polarization field still shields.

In order to develop the toner image, the surface charge must be on the ferroelectric are degraded. It is sufficient to generate the toner image that the compensation of the Polarization is disturbed by the surface charges. The cancellation of this compensation The polarization due to surface charges is achieved by heating the structure in a causes an electrically insulating atmosphere.

The disturbance of the compensation equilibrium is thereby caused by the Temperature dependence of the strength of the polarization in the ferroelectric caused. This means that the temperature change in the printing form also increases the strength of the the polarization caused electric force line field changes and is the equilibrium compensation between the surface charge and the electrical one Force field canceled. You get an electric field, the strength of which is Difference between the surface charge and the electric lines of force of polarization is equivalent to. In this state, the latent image can come into contact with a toner are brought and converted into a visible toner image. Around a temperature gradient in To prevent the printing form, the temperature is changed uniformly. In this The strength of the electric field generated in this way is the strength of the latent one Polarization image proportional. That under the influence of the electrical generated in this way The developed toner image has the same gray scale as the original.

The previously described development of the toner image of an FE-PC structure however, it is only descriptive and only one of the ways in which the toner image can develop. In the development process described above, the pyroelectric effect is used exploited. This method of development is therefore hereinafter referred to as pyroelectric Designated development process.

The toner image obtained in this way is applied to the one to be printed Material, the copy carrier, transferred in a known manner. This transmission method are used in the xerographic process. In contrast to the usual However, the transfer process can use one and the same latent image several times Toner image are transferred to the copy carrier. Erasing the latent image on the copy intermediate carrier is optional.

If the FE / PC element described above is used using a clear Ferroelectric is built up, can also be applied to the photoconductive layer Electrode must be opaque and the one on the opposite side directly on the electrode attached to the ferroelectric must be transparent. In this case it will the image of the template through the ferroelectric onto the surface of the Focused photo conductive coating.

In the following a printing form of the invention is described, the can be controlled and written to in a grid-like manner by electrical signals.

The matrix element which forms the essential part of the printing form consists from a thin disk of a ferroelectric, in which by the action of an external Field a ferroelectric polarization can be generated or amplified. on one of the surfaces is a family of parallel, equally spaced row electrodes applied from each other. A group of column electrodes is perpendicular to the group of row electrodes applied to the same surface of the ferroelectric. The column electrodes are also thin-film strip electrodes, which are also identical to each other, and have the same spacing as the row electrodes. After applying of the row electrodes and before the application of the column electrodes is applied to the Row electrodes at the points of intersection with the column electrodes to be applied afterwards applied an insulator layer. The subsequently applied column electrodes run over these insulator layers so that the row electrodes are in each point are electrically isolated from the column electrodes. On the opposite side Several electrodes are applied to the thin ferroelectric plate ("third Electrodes ").

These third electrodes are designed and arranged so that place them on the intersection of the row and column electrodes on the opposite side Side of the ferroelectric corresponding points are arranged.

This includes the position and the area of the third electrodes determined so that the third electrodes correspond to the row and column electrodes in the Projection perpendicular to the main plane of the structure with the same face opposite. In the matrix element thus constructed, each of the third electrodes is through capacitors connected to each of the row electrode and the column electrode, whose Intersection on the opposite side the position of the respectively assigned third electrode certainly. In this way, the third electrodes form an equivalent circuit for Electrode matrix on the opposite side of the ferroelectric. There on the other hand the third electrodes with both the row and column electrodes are connected, so are the row electrodes and the column electrodes with each other connected to each other via two capacitors connected in series. So if a electrical signal, which corresponds to a certain grid point, to a certain Row electrode and given column electrode are the area of the ferroelectric between the row electrode and the opposite third electrode, and the area of the ferroelectric between the Column electrode and the opposite third electrode is located in opposite Polarized directions. If the matrix element according to the method of voltage coincidence is controlled, a raster image is created in the thin ferroelectric plate built up a corresponding polarization pattern. In contrast to the one previously described FE / PC element, the matrix element has several third electrically isolated from one another Electrodes on one of the surfaces of the ferroelectric, each of the picture elements is electrically isolated from each other from the other picture elements. Through this training the charge points corresponding to the image points or raster points are prevented from being of the charge grid, which is generated according to the polarization pattern, with each other short-circuited by the electrodes. However, this measure does not prevent that the electric field lines of the polarization pattern as in the case of FE / PC elements are compensated and shielded by the surface charges. Therefore must also for the matrix element before the development of the toner image the entire printing form are subjected to a temperature change around the compensation equilibrium to interfere between the surface charges and the electrical polarization field. The toner development and subsequent treatments are therefore made for the matrix element carried out in the same way as described above in connection with the FE / PC element became.

It is already mentioned above that the printing form also has row electrodes on one side of the ferroelectric and column electrodes on the opposite Side of the ferroelectric can be formed. Likewise, the ferroelectric Platelets can also be provided with electrodes for displaying numbers and characters.

Both for the production of the FE / PC element and for the production Matrix elements can not only perroelectrics in the actual closer physical Meaning are used, but also those materials in which a stable ferroelectric Polarization due to the action of an external electrical field or a mechanical one Force can be generated. The latent image storing plate of the invention can also be made from this material.

As stated above, in the context of this invention under the term "ferroelectric" also means this material which can be polarized under the action of a field Understood.

In the above description, an external electric field used to generate the polarization pattern in the ferroelectric. To the same However, a mechanical force can also be used for this purpose.

Instead of the temperature change described above to change the The strength of the polarization can also be an external electrical one field or a mechanical force can also be used. Finally, the toner image can can also be generated in such a way that the copy medium, for example a sheet of paper, when applying the toner between the printing form, i.e. between the ferroelectric, and bring the toner.

This puts the toner directly on the copy medium and not on it first the ferroelectric applied.

Example 1 PbO, ZrO2, TiO2 and La203 are made according to the target composition Pjb0.924La0.076CZr0.70Ti0.30) 0.981 weighed in and mixed homogeneously with each other. The Gemiscl is baked at 800.degree. C. for 2 hours. This is created by solid-state reaction the compound PLZT-7,6 / 70/30 of the chemical formula above. The received Product is crushed, mixed again, heated to 1200 ° C and at one pressure hot pressed from about 1.4 N / cm² for 20 h to a transparent ceramic. The one with it The ceramic disc obtained has a diameter of 55 mm and a thickness of 10 mm. This disk becomes a square disk with the dimensions 35 mm x 35 mm x 0.5 mm cut.

The two main surfaces of the plate are then polished, so that the square plate finally used with one edge length 35 mm thick, 200 μm thick, has an optically flat surface.

This plate is in Figures t and 2 with the reference number 1 provided. On a surface of the ferroelectric disk produced in this way a photoconductive coating 2 applied in a thickness of 1.2 / µm.

A trinitrophenol sensitized is used as the photoconductive material Polyvinylcarbazole (hereinafter referred to as prCz) is used. The coating is carried out by a rotation process. About half of the cut sample plates will so coated. The resulting photoconductive coated PL2T disks are on a water-cooled sample holder of a cathode sputtering device is attached. The cathode of the sputtering device is a solid solution of 9 mol-ci / o SnO2 in 91 mole percent In203. The atomization takes place under high frequency under argon. Included becomes a transparent thin film electrode 3 at a relatively low temperature deposited on the PVCz surface.

The rest of the PLZT test specimens are placed on a heated sample holder the described cathode sputtering system and at 400 OC with the In203-Sn02 solution sprayed. Transparent thin-film electrodes 3 are obtained, which have a ' have an electrical resistance of about 5 ohms per plate. On the opposite A PVCz cover 2 is coated on the surface in the manner described above.

The two PLZT test items produced in this way are placed on one side of the entire surface coated with a liquid 5 based on glycerine. To this Liquid is placed on a glass substrate 4 (Nesa glass) that has a transparent thin-film electrode 6 carries. The structure is designed in such a way that that the coated with the transparent thin-film electrode surface of the PLZT disk 1 points outwards and the one constructed in the manner described above Liquid electrode applied to the electrode-free surface of the ferroelectric will. Special care is taken to ensure that the glycerin is perfect is free of bubbles. With the help of a conductive silver paste, a lead 3 'is connected to the transparent Thin film electrode 3 connected on the PLZT side. In the same way, a Supply line 6 'connected to the transparent thin-film electrode 6 of the Nesa glass. This structure is fastened to a thermosetting plastic frame 7 with a clamping bracket 8. The leads 3 'and 6' are connected to connections 9 and 10 on the frame attached are. The two different ones obtained in this way Types of FE / PC elements are denoted by A and B, respectively.

The FE / PC element A has a thin-film electrode on the PVCz coating and corresponds to the element shown in FIG. The FE / PC element B corresponds to in Fig. 2 and is by a liquid electrode on the PVCz coating marked.

An original is focused on the PVCz surfaces of the elements A and B obtained in this way. A direct voltage of about 120 V is applied to the connections 9 and 10 of the elements. The image of the original focused on the PVCz surface is written into the element as a latent electrical image and stored there. Since, under the influence of the very high writing voltage, a f W xrrOc au Aef C c4 ctritc polarization is generated in the PLZT wafer, the latent image can be recognized as a haze pattern in the transparent wafer due to the strong optical scattering in the polarization regions.

When the electric latent image in the way in the FE / PC elements is written in that the writing voltage is polarized so that the PVCz-tberzug is at positive potential, the writing of the latent image within a shorter period of time than if the write voltage is polarized reversed is. Accordingly, the polarity becomes positive for normal copying the write voltage applied to the FE / PC image storage elements laid the side of the PVCz-Uberzuges. Qualitative is between the two write voltage poles however, no difference was found. The one established once in the ferroelectric latent images can no longer be seen afterwards, whether they are positive or negative writing voltage with respect to the PVCz coating.

When using an FE / PC element for the xerographic copying process however, the difference in polarization direction occurs in the developed toner image to the extent that once a negative of the original1 appears the other time Positive of the original is received.

The definition or the writing of the latent image in the manner 1 that the positive pole of the applied external electrical voltage, i.e. the writing voltage, on the PVCz photoconductive layer is referred to briefly below as recording or writing with positive polarity.

If both the FE / PC elements of row A and row B with positive polarity is described for the FE / PC elements A when developing Get a positive image of the template while using the FE / PC elements of the series B a negative toner image of the original is obtained. This is explained in more detail below described.

When using an FE / PC element for the xerographic copying process depends on the positive / negative ratio between the original and the developed image or Copy once depending on whether elements of type A or type B are used, and on the other hand it depends on whether the write voltage has a positive or negative polarity is written.

When making normal copies, the copy should normally be have the same image as the original. Original and copy or developed image must therefore have a positive / positive ratio to one another. Sometimes, however, should A positive should be produced from a negative original or should be produced from a positive one Original negatives can be peeled off. It is therefore extremely desirable optionally change and set this positive / negative ratio to can. An embodiment of the invention that enables this optional setting, is described below.

Positive and negative images are produced as templates. from For each FE / PC element in row A and row B, four test objects are produced. First, the positive template is used. The picture of this positive template is focused on the PVCz surface of the FE / PC element A.

At the same time, a positive write voltage is used to set the latent image is applied, i.e. a voltage across the element that is polarized that the positive potential is on the side of the PVCz layer. This element is denoted by the symbol "A (+, +)". Then the positive picture of the template is focused on a second FE / PC element A. In doing so, however, one becomes negative polarized writing voltage applied, i.e. an electrical voltage across the element, which is polarized in such a way that the PVCz side is polarized negatively. This element comes with denoted by the symbol "A (+, -)". Using FE / PC elements B and definition of the latent image in the manner described above, the elements B (+, +) and B (+, -). With the manufactured in this way using a four elements described in the positive template A (+, +), A (+, -), B (+, +) and B (+, -) positive latent images are provided when viewed in scattered light are indistinguishable from each other.

In the same way as previously described, negative originals are made used in connection with the printing forms described, where the elements A (-, +), A (-, -), B (-, +) and B (-, -) can be produced.

A total of 8 elements are thus obtained in this way, the latent save electrical images. The 8 elements are developed with a toner. The positive / negative ratio between original and print (copy) is examined.

Before development, each of the 8 FE / PC elements is converted into an alcoholic Immersed in liquid. Then the PLZT disc is peeled off the Nesa glass. The surface of the printing form, which has been freed from the electrode, is treated with clean alcohol washed and dried. After removing the connecting wires, the development preparation is done closed.

A liquid developer is used for development.

This is prepared in such a way that one part by volume of a concentrated Toner containing 9 parts by volume of a commercially available non-flammable solvent diluted and the toner particles dispersed under ultrasound.

About 200 ml of the liquid developer 12 are placed in a watch glass 11 given with a diameter of 10 cm (Fig. 3).

The test specimen, each a PLZT disk 1, which has a latent electrical Image bears is placed in the liquid developer. The test object will be like this placed in the bath with the surface freed from the electrode facing up. In the case of elements A, this is the free and cleaned PLZT surface, im In the case of elements B, the surface of the PVCz layer.

After placing the PLTZ plate in the liquid developer In the watch glass a 200 W IR lamp 13 is switched on, which is at a height of about 10 cm above the watch glass. Via a voltage regulator 14 with program control the operating voltage of the lamp is gradually increased from 20 to 40 V. This will the test object evenly and gradually warmed up. The latent electrical image is developed flawlessly and sharply. The development time is in the range of a few to a few dozen seconds.

The course of development can be followed with the naked eye. The lamp is switched off before overdevelopment can occur. After developing the PLZT disc is taken out of the bath and immersed in a bath that contains the pure solution that was also used to dilute the toner bath. The excess toner is easily washed off in the solvent wash bath. The PLZT disc is then left to dry on a rack. The drying is ended after about 5 minutes. This also concludes the development stage and is the test specimen prepared in such a way that the toner image is transferred to the copy medium can be.

The positive / negative ratio between the original and the developed one Toner image is for the 8 elements A (+, +), A (+, -), A (-, +), A (-, -), B (+, +), B (+, -), B (-, +) and B (-, -) are summarized in Table I.

Table I Positive / negative ratio toner image / original and polarity of the writing voltage positive negative Original polarity of the writing voltage positive negative positive negative element A positive negative negative positive ves image ves Picture ves picture (fast) (long-picture (slow) sam) (schndl) Tabel I (continued) Element B negative positive positive negative ves tives image image Image Image (slow) (fast) (slow (fast) sam) In the table "fast" means and "slow" indicates the speed at which the latent image is being written or could be determined.

Since the toner used is positively charged, it sticks to the negative Surface charge of the PLZT element.

On the other hand, since the surface coated with the electrode is a Is the equipotential surface, practically no toner adheres to it. The surface, to which the toner adheres is hereinafter referred to as the binding surface. If that latent image on the bonding surface is positively charged, so if the potential the writing tension on the side of the binding surface is greater than on the opposite Page is up, the toner selectively adheres to the A-FE areas.

On the other hand, if the latent image on the bonding surface is negatively charged is when, therefore, the potential of the writing voltage on the side of the bonding surface lower than the opposite side, the toner selectively adheres to the FE area.

The toner image or this toner image developed in this way load-bearing element has essentially the same properties as a common one xerographic copy carrier. The toner image on the so developed element can in the usual way on an electrostatically charged paper or an electrically insulating sheet, such as an acetate film, are transferred.

After the toner image has been transferred, there may be some residue on the surface Toner adhering to the FE / PC element by lightly rubbing with alcohol completely removed from the moistened cotton ball. The element so treated then still carries the latent electrical image in a stable and unchanged manner. At the re-immersion in the developer bath is carried out in the manner previously described perfectly identical circumstances an equally clear and qualitatively excellent received new toner image from the same latent image.

This toner image can be transferred to the copy carrier in the same way will. It is used to check the image quality of one and the same element with Numerous prints were made from the latent image without any deterioration the copy quality can be determined.

After the required number of prints has been made, the FE / PC element, whose latent image is no longer needed, at about 90 OC warm for one minute Submerged in water.

The element is then cooled to room temperature and dried. By this treatment can completely erase the latent image on the element. If an element treated in this way is again subjected to the development in the toner bath described above is subjected to a completely empty copy carrier when the copy is made obtain. The element completely deleted in this way or the completely deleted printing form, can be rewritten and again to produce numerous Deductions are used.

Example 2 Highly pure powders of PbO, TiO2 and La203 are made according to the specifications of the target composition Pb0.93La0.07 (Zr0.65Ti0.35) 3.93403 weighed in and thoroughly mixed together. In the above formula of the target composition is the Index referring to the elements zirconium and titanium outside the Brackets refer to reading as a mixed fraction with the decimal value of 0.983.

The weighed and homogeneously mixed mixture is then at 800 to Burned 900 OC. The compound 7/65/35-PLZT is formed by solid-state reaction with the specified chemical composition. The product is crushed and mixed and 5 to 500 h in a stream of oxygen at 1200 ° C under pressures in the range from 1.4 to 3.5 kN / cm² hot-pressed. The product obtained under these conditions is cut from the shape with a diamond drill. The ceramic obtained in this way is cut into thin, transparent slices and optically polished.

Ceramics of the system Pb 1xLax (Zr1yTiy) (14O3 are solid solutions, in which the values for x and y can be chosen freely and independently of one another. However, the properties of the products depend very much on the properties for x and y selected values. Therefore, the one already mentioned briefly in the following is Nomenclature to identify the compounds of this system introduced in the the molar ratios of the solid solutions multiplied by a factor of 100 in the Form x / (1-y) / y-PLZT can be specified.

So 7/65/35-PLZT means a solid solution of the composition Pb0.93La0.07 (Zr0.65Ti0.35) 3.93403.

This substance 7/65/35-PLZT is a clear ceramic with ferroelectric Characteristics. For this example, an optically polished disc of the ceramic is used with the dimensions 30mm x 40mm x 150 to used. On the surface of this ferroelectric platelets are 30 row electrodes in the manner of an orthogonal matrix and 30 column electrodes are applied. It is true that the ferroelectric used here is Transparent in the form used, but can be used with practically the same success basically any also opaque ferroelectric be used.

The only prerequisite is that this element has matrix electrodes is clearly controllable according to the half-voltage method.

The printing form used in this process is shown in FIG. On one surface of the rectangular 7/65/35 PLZT disk 21 are 30 line electrodes 22 with a width of 500 / um and a length of 29 mm and a distance of 1200 um each other parallel to the shorter, 30 mm long edge of the rectangular Ferroelectric plate arranged. The electrodes are made by vapor deposition of gold made in vacuum. 30 column electrodes are perpendicular to the row electrodes 23 with a width of 600, a length of 39 mm and a spacing of 900 μm applied to each other. To avoid short circuits between the column electrodes and the To avoid row electrodes, one brings after the production of the row electrodes 22 electrically insulating SiO2 layers 24 by vacuum vapor deposition in the in Fig. 4 shows the points of intersection between the column electrodes and the row electrodes.

The column electrodes 23 are then subsequently formed by vapor deposition made in vacuum. The column electrodes and the row electrodes have lead wires made of gold.

On the back of the rectangular PLZT plate are 30 x 30 gold electrodes 25 applied, each having a dimension of 800 / um x 1000 / um. The electrodes are applied by vacuum evaporation so that they are electrically separated from each other are isolated. The electrodes 25 on the back of the structure are very precise arranged so that they are perpendicular to the main plane of the structure when viewed respectively are placed exactly below the point on which on the front side of the structure, the insulator layers 24 and the column electrodes 23 with the ceramic stand in touch. The matrix produced in this way is placed on a frame-shaped holder attached. One element of this matrix is shown in detail in FIG.

The function of such a matrix element is based on the equivalent circuit diagram explained in FIG. 6.

The equivalent circuit shown in FIG. 6 for the matrix of the printing form At first glance, the invention resembles a common matrix. However, in the details it differs very significantly from the known matrix forms. To emphasize this difference, two in A series of factors connected to one another is shown. If one takes into account in the in 6b shows a row electrode 22 and a column electrode 23, so are the area in which the element 21 is in contact with the electrode 22, and the area in which the element 21 is in contact with the electrode 23, connected to one another via the electrode 25. Since both areas are equal in area, they become when an electrical voltage is applied to the electrodes 22 and 23 in the opposite manner as indicated in FIG. 5 by arrows 20 and 20 ' Polarized direction.

The electrodes 22 and 25 thus form a capacitor C1, while electrodes 23 and 25 form a second capacitor C2. One electrode of the Capacitor C1 and an electrode of capacitor C2 become one and the same Plate formed. This structure corresponds to the equivalent circuit diagram shown in Fig. 6b, after which the capacitors C1 and C2 are connected between the two electrodes 22 and 23 are. A capacitor C3 is formed directly by the electrodes 22 and 23. the Capacity of this capacitor C3 can however be neglected, because its electrode spacing is much smaller than the electrode spacing in the capacitors C1 and C2 is. The dielectric coefficient of those lying between the electrodes Substance, in this case Si02, is smaller than for the capacitors C1 and C2.

It is assumed that between the electrode distances d1, d2 and d3 of capacitors C1, C2 and C3 have the relationship d1: d2 d3 = 10: 10: 1 with one Ratio of the dielectric constant of these three capacitors of 100: 100 : 4 exists. The capacities of the capacitors are therefore in the ratio C1: C2 : C3 = 100: 100: 40 to each other. The capacitance of the capacitor C3 is therefore not even half the capacity of either of the other two capacitors. The ferroelectric 21 used in this example is exceptional strong ferroelectric with very stable polarization. Even with a short circuit between the electrodes 22 and 23 is stored in the form of the polarization states Image information not affected.

The printing form constructed in this way works in the same way as a common ferroelectric matrix memory element. Write and read can, as is known per se for this memory, scanning point by point, scanning line by line or in free access according to the method of coinciding half-value voltages take place. To drive the matrix (driver parameters of the matrix control) Half-value voltages with levels of +100 V and -100 V for 60 / us to the respectively controlled Electrodes 22 and 23 applied1 while all other, non-activated electrodes 22 and 23 are earthed. Under these conditions only the one under the intersection will be The raster element of the ferroelectrics lying next to the driven row electrode and touch electrode under the action of the full 200 V over the entire layer thickness of the ferroelectric polarized. After Polarization of the activated raster point another row / column electrode pair is activated. Both electrodes will applied to the half-value voltage, while the other electrodes are grounded. The activated raster point is polarized. In this way can be on the scene the matrix the information to be displayed can be built up in grid form. The printing form carries a latent raster image. With subsequent toner development, the registered Information image can be read directly with the naked eye. The toner development takes place in the manner described in Example 1.

The matrix element described with the information becomes the insulating treatment subjected, so that the electrical insulation between the row electrodes and the column electrodes on the surface of the matrix element is retained. Afterward the element is immersed in the liquid developer.

The liquid developer is prepared in such a way that 1 Part by volume of a concentrated toner with 9 parts by volume of a commercially available one diluted non-flammable solvent. The toner particles are then homogeneously dispersed by ultrasound.

In the manner shown in Fig. 3, about 20 ml of the so prepared liquid developer 12 placed in a watch glass 11 with a diameter of 10 cm. The memory element described is placed in the developer bath so that the rear Electrodes 25 of the storage element point upwards.

Then the 200 W IR lamp attached 10 cm above the watch glass is used 13 switched on. The voltage is controlled by a program-controlled voltage control on the IR lamp gradually increased from 20 to 40 V. This will the sample is gradually heated, with the latent electrical image during some Seconds is clearly developed.

A line pattern is used as an example using the method described above inscribed point by point in the matrix element.

During development, the toner particles are deposited on the activated ones Areas of the electrodes 25 on the back of the matrix element. The grid appears as a slight stripe, with the stripe through the linear Result of the rectangular grid points is caused.

Before overdevelopment begins, the IR lamp is switched off and the matrix element is removed from the watch glass. Unnecessary toner is easily removed Immerse in a fresh bath of the solvent that is also used to dilute the toner is washed off. The matrix element is then left to dry on a bench. The drying process is over after 5 minutes. This concludes the development stage and the toner image can be transferred.

The toner image can be in the manner described in Example 1 in a Copy carriers are transferred. The one after the transfer on the electrodes of the matrix element Remaining toner can easily be removed with a cotton ball soaked in alcohol removed. The latent image remains stable even after repeated development are in the matrix element. In this way, practically any number of development processes can be carried out and transfer processes are carried out, so practically any number of copies can be made drawn from the same latent image. Doing so during development no change observed even with high copy numbers. In contrast, the wiping led the gold electrodes 25 with the alcohol-soaked cotton ball gradually scarring of the electrode surface.

When the latent image stored in the element is no longer available for manufacture of prints is required, it can be deleted so that the matrix element is new and new copies can be made of this. Deleting the The matrix element is carried out in such a way that you can use the element for a few minutes Long heated to 150 OC and thereby the row electrodes 22 and the column electrodes 23 short-circuits. After cooling to room temperature, the latent electrical image is completely deleted. A new development of the element leads to a perfect empty area.

The matrix element used repeatedly in the manner described above shows no signs of fatigue after being deleted when used again is indistinguishable from a new element. It can be used multiple times.

Example 3 In the manner described in Example 2, a 7/65/35 PLZT platelet is made with the dimensions 30 mm x 30 mm x 150 / um with optically flat-ground surfaces manufactured. A matrix element with that shown in FIGS. 7a and 7b becomes Structure made.

On one surface of the thin plate 41, 30 are strip-shaped Row electrodes 431, 432, ..., 4330 each with a width of 500 / µm, a length of 29 mm and a distance from one another of 1200 / µm parallel to the shorter, 30 mm long side of the substrate applied. The electrodes are by Evaporation of gold layers deposited in a vacuum.

Furthermore, on one of the main surfaces of a glass plate 44 with the dimensions 30 mm x 40 mm 30 strip-shaped column electrodes 461, 462, ..., 4630 with a width of 600 μm each, a length of 39 mm and a distance from one another of 900 / µm parallel to the longer side of the substrate, i.e. parallel to the 40 mm long side Edge, applied.

The electrodes are again applied by vacuum evaporation Gold layers. The row electrodes and the column electrodes are connected to terminals or 46'1, ...., 46'30 provided. The electrode-free surface of the PLZT plate 41 is placed on the surface of the glass plate provided with the column electrodes 44 connected with the interposition of a glycerine layer 45 in such a way that the two groups of electrodes run perpendicular to each other.

The grid element produced in this way can be used in a manner known per se Point by point, line by line or with free access according to the half-value voltage coincidence method to be written. The matrix is generated with signal levels of +100 V and -100 V (half-value voltages) driven, the 60 ms to the respectively driven column and row electrodes be created.

The remaining, non-activated electrodes are all grounded.

This acts on the grid element that is below the intersection of the driven row electrode and column electrode, the full polarization voltage of 200 V. In this way, only the one below the intersection will be controlled Selectively polarized grid area lying on electrodes. Then the next one raster point controllable via its corresponding row electrode and column electrode polarized. In this way, the ferroelectric wafer is pixel-wise built up the desired electrical latent image. If the element so polarized is then subjected to toner development, the stored information occurs readable to the naked eye emerged.

In the case of the element described above, at first glance the There is a risk that the glycerol liquid 45 shortens the column electrodes 46 closes. In practice, however, this is not the case because the glycerol liquid layer 45 is very thin and the layer is practically only an electrical conductivity component in the direction of the layer thickness, but practically no component in the plane of the structure having. The short-circuit currents that occur are so minimal that they can be used in practical Operation of the element does not matter.

The element described is developed in the example 1 described way. After making the desired number of copies, the latent Image can also be deleted in the manner described in Example 1.

A new picture can then be entered.

Example 4 The printing form used to print out numbers and characters is shown in FIG. In the manner described in Example 2, a rectangular thin 7/65/35 PLZT plate with optically polished surfaces and a thickness of 150 µm. Electrodes are placed on one surface of the chip 51 53 in the form of the 7-segment structure applied by vapor deposition of gold in a vacuum.

The back of the plate 51 is not coated.

The surface of a Nesa glass plate 54 with slightly larger edge dimensions as the PLZT plate 51 is bonded to a unitary electrode 56 by vapor deposition coated by gold in a vacuum. The uncoated surface of the platelet 51 is coated with the electrode 56 by a glycerine liquid 55 Surface of the Nesa glass plate 54 applied. The display segments are with leads 53 'and the rear large electrode 56 with a lead 56 'provided.

Between the respectively activated display segment electrodes 53 and a direct voltage of 200 V is applied to the base electrode 56. The Ferroelectric in the form of a polarization pattern in the numerical representation or Character representation generated corresponding latent electrical image.

This is described in the manner described in Example 1 Platelets subjected to toner development.

The produced toner image of the number or character can thereby be made visible and transferable. In the manner described in Example 1 this element can also be deleted and used again.

Example 5 In the manner shown in Fig. 9, on a transparent Electrode 3 of an FE / PC element of the type described in Example 1 and shown in FIG. 2 shown type B metal electrodes 15 and 15 'along opposite one another Applied edges. The electrodes are metal electrodes that are vapor-deposited in a vacuum. The electrodes are provided with connecting wires 16 or 16 '. In the example In the manner described in Fig. 1, a latent electrical image is shown in the FE / PC element generated a predetermined pattern. The PLZT plate is then removed from the Electrode removed and washed.

A voltage of approximately 20 V is applied to terminals 16 and 16 '. The current flowing through the electrode 3 heats it up. At the same time will the PVCz surface 2 is brought into contact with a charged toner. Under these Conditions will be the development under the circumstances described in Example 1 carried out in the shortest possible time. That developed in this way Toner image can be transferred to a copy carrier in the manner described. After the required number of copies have been made, the latent image can be used as before can be deleted. The element is available for reuse.

The development described above is particularly suitable for FE / PC elements of type B. It is less suitable for FE / PC elements of type A, since the heating would have to take place via the photoconductive layer, which is the development difficult.

In the manner described in the examples, the toner development be carried out both by the dry process and by a wet process. Both Development processes can be carried out using the pyroelectric effect will. The heating can be done by IR rays or by Joule heat. Also Can be heated by radiant heat from electrical heating elements or by Thermal conduction can be made. Finally, a heated toner can also come on the surface bearing the latent electrical image. During wet development cooling can also take place by cooling the developer bath.

The pyroelectric development can then be carried out with a particularly high degree of efficiency be carried out when the ferroelectric Curie temperature, i.e. the temperature in which the ferroelectric phase including that caused by the application of the external Electric field induced polarization disappear is relatively low and large amounts of charge are generated at room temperature. For such a material Particularly pronounced effects can be achieved with only slight heating. The composition of the material 7,6 / 70/30-PLZT is directly in the range of a morphotropic phase boundary. When increasing the molar ratio of Zr or La the substance goes into the paraelectric state. With reduction of the zirconium or lanthanum content, the connection is in the ferroelectric range Phase. When heating the aforementioned compound to a temperature of about 35 ° C or above, the ferroelectric phase disappears. The 7.6 / 70/30 PLZT material that is, in connection with a pyroelectric development process, is at 20 to 25 0C the optimal material for the method of the invention when applied in the sense a xerographic copying process.

Finally, let us return to the elements FE / PC-A and FE / PC-B received. In the case of element A, the surface bearing the toner image is the exposed surface of the ferroelectric. In the case of element B, this is the surface forming and bearing the toner image is the surface of the photoconductive Coating. In the case of element B, the photoconductive coating may be made of a relatively hard material so that it also acts as a protective layer. If the photoelectric coating is too soft, however, the Element occur. However, element B has the advantage over element A. a better image resolution.

In addition, in the manner described in Example 1, the latent electrical image can be created in less time if you use the write voltage is applied so that the potential across the photoconductive coating is higher than that Potential is on the other side. With the FE / PC elements of the one shown in FIG Type B copies can therefore be obtained that match the original with a higher resolution reproduce, with these copies also taking place in much less time than the elements of type A can be obtained by connecting the Sceibspannunj to the elements B is applied so that the higher potential is applied to the side of the photoconductive coating will.

Series tests have shown that good and very good results for obtained ferroelectric platelets with a thickness in the range of 0.01 to 10 mm will. For the practice of the method and apparatus of the invention the ferroelectrics of the elements preferably have this thickness.

Claims (18)

Claims 1. Copying process, in that it is not possible to (a) a ferroelectric or an induced ferroelectric material, its ferroelectric Polarization under the influence of an external electric field or a mechanical one Force can be intensified, pictorially an external electric field or a mechanical force and thus an image-like effect on the surface of the material ferroelectric polarization pattern produces that one (b) in the material a Change of an external electric field, a mechanical force or a Heat to temporarily change the strength of the ferroelectric polarization generated so as to match the pattern of ferroelectric polarization on the material surface to generate a corresponding image-wise charge pattern that can be achieved by adsorption of a toner generates a toner pattern on the charge pattern and that one (c) the so obtained toner image is transferred to a copy carrier. 2. The method according to claim 1, characterized in that g e k e n n z e i c h -n e t that in process step (a) an external electric field in terms of image the ferroelectric acts. 3. The method according to claim 1, characterized in that g e k e n n z e i c h -n e t that in process step (a) an external electric field in terms of image a material acts, under the influence of an external electrical Field forms a stable ferroelectric polarization or amplifies such. 4. The method according to any one of claims 1 or 2, characterized in that the strength of the ferroelectric remanent polarization is changed in process step (b) by a change in temperature. 5. The method according to any one of claims 1 or> thereby g e k e n nz e i c h n e t that in process step (b) by increasing the temperature the strength of the ferroelectric polarization changed. 6. The method according to any one of claims 1, 3, or 5, characterized g e k It is indicated that one of the following is chosen as the material: BaTi03, TGS, Pb (Zr, Ti) 03, (Pb, Sr) (Zr, Sn, Ti) 03, (Pb, Sr) (Zr, Sn, Ti) NbO3, (Pb, Ba) (Zr, Hf, Ti) 03, (Pb, La) (Zr, Ti) 03, (Pb, Sr, Ba) (Zr, Ti) 03, (Pb, La, Sm) '(Zr, Ti) 03 and (K, Na) Nbo3. 7.jDruck form for performing the method according to one of the claims 1 to 6, not shown by a thin disc made of a material, under the influence of an external electric field or a mechanical one Force creates or amplifies a stable ferroelectric polarization state, through a photoconductive coating on a surface of the material disk, through a first electrode on the rear surface of the material disc and by a second electrode on the photoconductive coating, wherein at least one of the two electrodes is designed to be removable. 8. Printing form for performing the method according to one of the claims 1 to 6, indicated by (a) a thin substrate made of a material under the influence of an external electric field or a mechanical one Force creates or amplifies a stable ferroelectric polarization state, by (b) several strip-shaped row electrodes parallel to one another on the Surface of the substrate are applied by (c) several strip-shaped column electrodes, the parallel to each other orthogonal to the line electrodes with the interposition of a Insulator layer applied to the same substrate surface as the row electrodes are, and by (d) several electrically independent electrodes on the opposite substrate surface on areas of that surface containing those points include the intersections of the row electrodes and the column electrodes on the opposite surface exactly opposite, so that this mutually independent electrodes on the back of the substrate reflect the geometry of the Line and Column electrodes on the front of the substrate as Punktra st he depict. 9. Printing form for performing the method according to one of the claims 1 to 6, not shown by a thin substrate made of a material, under the influence of an external electric field or a mechanical one Force creates or amplifies a stable ferroelectric polarization state, by a bevy of strip-shaped row electrodes that are parallel to each other one of the substrate surfaces are applied, and by a bevy of strip-shaped Column electrodes that are orthogonal to the row electrodes on the opposite Substrate surface are brought to or interact with this, at least either the group of row electrodes or the group of column electrodes can be removed is trained. 10. Printing form for performing the method according to one of the claims 1 to 6, not shown by a thin substrate made of a material, under the influence of an external electric field or a mechanical one Force develops or strengthens a stable ferroelectric polarization state, segment electrodes composed by characters on one of the substrate surfaces and a base electrode covering the entire opposite substrate surface. 11. Printing forme according to one of claims 7 or 9, characterized g e k e n nz e i n e t that the removable electrodes are in the form of an electrically conductive viscous liquid layer are formed. 12. Printing forme according to one of claims 7 or 11, g e -k e n n z e i c h n e t by a photoconductive layer made of doped or undoped polyvinyl carbazole, CdS, CdSe, ZnS, ZnSe, Se or ZnO. 13. Printing forme according to one of claims 7 to 12, characterized in that g e k e n It should be noted that the fixed electrode or electrodes are transparent are. 14. Printing forme according to claim 13, g e k e n n z e i c h n e t through a transparent thin film electrode made from a sputter deposited solid In2O3Sn02 solution, from an In203 layer evaporated in a vacuum, from a SiO2 layer evaporated in vacuo, from a TiO2 coating evaporated in vacuo, from a vacuum vapor-deposited ZrO, coating and a doped or undoped one produced by spraying and thermal decomposition of an aqueous SnC14 solution SnO2 layer. 15. Printing forme according to one of claims 7 to 14, characterized G It is not noted that the ferroelectric substrate consists of one of the following Materials consists of: BaTi03, TGS, Pb (Zr, Ti) 03, (Pb, Sr) (Zr, SnTi) 03, (Pb, Sr) (Zr, Sn, Ti). Nb03, (Pb, Ba) (Zr, Hf, Ti) 03, (Pb, La) (Zr, Ti) 03, (Pb, Sr, Ba) (Zr, Ti) 03, (Pb, La, Sm) (Zr, Ti) O and (K, Na) Nb03. 16. The method according to any one of claims 1 to 6, characterized g e k e n It is not indicated that one can work on the printing forme after completion of process stage (c) Adhering toner residues removed and with the same printing form after renewed adsorption of a toner carries out process step (c) and these two process steps repeated according to the desired number of copies. 17. The method according to any one of claims 1 to 6 or 16, characterized in g I do not see that one can do so after the completion of the last procedural stage (c) the printing form to a temperature above the ferroelectric phase transition temperature lying temperature to cancel the imposed ferroelectric polarization heated and at the same time either the electrodes of the printing form with each other short-circuits or applies an opposing voltage in order to generate the stored latent electrical To erase the image and the surface charges on the surface of the printing form, and that you can then process steps (a), (b) and (c) with the same printing form repeated, the process step (c) after re-developing can be repeated several times with one toner. 18. The method according to any one of claims 1 to 6 or 16, characterized in that g I do not see that one can do so after the completion of the last procedural stage (c) the printing form is immersed in hot water, the temperature of which is above the ferroelectric Phase transition temperature is at which the impressed ferroelectric polarization state of the material 5 is lifted, with the latent by the immersion at the same time erases the electrical image and the surface charges on the printing form, and that then process steps (a), (b) and (c) with the same printing form repeats process step (c) after renewed development with a toner, if desired multiple. L e r s e i t e