DE3006781A1 - METHOD AND COPIER FOR DEVELOPING LATEN CHARGE IMAGES - Google Patents

Description

DR.-ING. QIPL.-ING.M. SC. DIP 'P - I "S. OR. DIPL.-PHVS.

HÖGER - LEGAL RIGHTS - GRiESSBACh - HAECKER BOEHME

PATENT LAWYERS IN

A 43 947 b Applicant: Savin Corporation

February 19, 198o Columbus and Stevens Avs,

k- 176 Valhalla, N.Y. Io595

United States

Method and copier for developing latent charge images

The invention relates to a method for developing a latent electrostatic charge image with a developer liquid, which consists of a dielectric carrier liquid with charged toner particles distributed therein and a copier for performing the method.

A number of methods are known for developing latent electrostatic charge images. This latent electrostatic charge images can be obtained by first charging a photoconductive surface and they are then exposed to light or ionizing radiation to turn the photoconductive material into the light or the To make areas exposed to radiation energy conductive, so that these areas flow away by the initially applied Charge to be "neutralized". An electrostatic latent image can also be deposited on a dielectric sheet-shaped material can be produced by using suitable "pens" to produce the desired electrostatic Create patterns.

The development of latent electrostatic charge images initially took place by means of fine particles due to

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the electrical attraction are attracted to the latent image areas, preferably particles which carried an electric charge whose polarity was that of the electrostatic latent charge Image was opposite. Usually dry particles were used, which is why for this development process the term "xerography" derived from the Greek language was used.

It was later found out that the fine toner particles can be suspended in a dielectric liquid and development can take place _; by immersing the latent electrostatic charge image in this developer liquid.

When using a dry powder as a developer, this was usually on plain paper or on transferred to another sheet-shaped carrier and fixed there by melting or baking. For this The process thus required thermal energy and also the use of fine fusible toner particles Resins. When using copy paper coated with photoconductive material such as zinc oxide, on the other hand, no transfer of a developed electrostatic charge image was necessary, since the Development directly on the copy paper with the aid of a developer liquid with toner particles contained therein he follows.

In the course of the advancement of the state of the art proved it is to avoid the need to bake one with the aid of powdered toner

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developed image is advantageous to the electrostatic latent image with a liquid developer and then transfer the developed image onto plain paper. The developer liquid passed usually from a hydrocarbon such as Isopar-G or the like as the carrier liquid in the Toner particles for developing the electrostatic latent image were dispersed. When immersing the photoconductive Surface with the latent electrostatic charge image in a bath of the developer liquid the entire surface of the photoconductor is moistened. In this process on the developed charge image the remaining amount of liquid developer could then be largely removed with the aid of a doctor roller or the like removed. However, a small amount of developer liquid always remained on the entire photoconductive surface Surface back. This developing liquid was used in transferring the developed image onto paper or another Carrier material was also transferred and then had to be dried. This led to the fact that a certain amount of carrier liquid that has been transferred from the photoconductive surface to the carrier material, had to be vaporized. Such an evaporation of the carrier liquid is undesirable for various reasons. First of all, not only a certain amount of energy is required for drying the carrier material, but also a certain drying time, which leads to a corresponding limitation of the achievable copying time. Furthermore, there is a constant change in the ratio of carrier liquid to toner material in the Developer liquid. After all, when using multiple copiers in a small room, that is constant Evaporation of carrier liquid is also undesirable.

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as this can impair the well-being or health of the user.

It is understood by those skilled in the art that it would be desirable if a latent electrostatic charge image could be developed in such a way that the developer liquid is transferred only to the charged image areas and not to the entire photoconductive surface on which the latent charge image was formed. In this case, the possibility of evaporation would be considerably reduced, since the image areas in a typical copy only make up an area of about 5 to 7%. If, however, a roller ₍ such as a pressure roller ^ is coated or wetted with the developer fluid and this roller is allowed to come into contact with the photoconductive surface that carries the latent charge image, then both the photoconductor and the latent charge image are completely covered with developer fluid So it remains both on the discharged background areas and on the charged image areas developer liquid, which normally reduces the contrast between the image areas and the background areas on the photoconductive surface, so that ultimately an unsatisfactory copy results With the aid of an application roller provided with depressions on its surface, toner is only transferred to the image areas of the latent charge image, while the background areas remain free of toner and developer liquid erpartikel in the developer fluid and thought of removing the developer fluid from the webs between the wells with the help of a scraper. It turns out, however, that the stripping of the developer liquid

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von der Stegen proved to be more difficult than it was initially assumed. In fact, the jetties failed to keep free of developer liquid with the help of the scraper, so that streaks resulted in the copy and no clear image was obtained. In addition, the higher the copying speed, there was an increase in Banding and thus a limitation of the per unit of time number of copies that can be produced.

Attempts have also been made to avoid it the difficulties identified above with the photoconductor contacting applicator rollers a distance between the applicator roller and the photoconductive surface and the developer liquid from the applicator roller to pull over the photoconductor under the action of the electrostatic field of the latent electrostatic charge image. These attempts were unsuccessful "in that the toned image was found to be out of focus and not was free from defects, which was due to the behavior of the developer liquid when it arrived was not predictable on the photoconductor.

Brief summary of the state of the art

The ÜS-PS 3 o84 o43 describes a copying process in which a belt is used which has protrusions and depressions and on which a layer is more conductive Ink is applied. In the known method, the belt is brought into contact with a photoconductive layer, which carries the latent electrostatic charge image.

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US Pat. No. 3,232,190 discloses the possibility of sufficiently using a film on which there are dry toner particles close to a latent electrostatic charge image so that the dry particles take over the existing Skip the gap and tone the charge image. In this process, however, the toner particles are burned in or fixed required after image transfer to a sheet-like support.

US Pat. No. 3,383,209 describes the use of a grooved applicator roller for applying a conductive one Ink on an electrostatic latent image. The application roller is in contact with the photoconductor, and toning is done by selective wetting.

U.S. Patent 3,486,922 describes the possibility of developing a latent electrostatic charge image with an aqueous, conductive developer liquid. It works with an applicator roller that is in contact with the surface carrying the electrostatic charge image. This surface is water-repellent, so that only the image areas are toned, but not the background areas of the water-repellent surface.

U.S. Patent 3,560,2o4 discloses the possibility of a water soluble one acidic or basic dye as a self-fixing ink. The surface with the latent electrostatic The charge image is guided past a rotating drum on which a layer of the ink is placed is provided, but without touching the drum. Between the drum serving as an applicator roller and one behind the charge image there is an electric field, so that a relocated

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Column of ink, each of which has the shape of the relevant image area, skips the gap and tinted one Image area generated. The use of non-polar liquids such as toluene or nitrile silicone is also considered and stated that these liquids do not skip the air gap as quickly as water-based solutions.

ÜS-PS 3 667 428 discloses the use of an applicator roller with a uniformly patterned surface that is suitable for applying developer material to a latent electrostatic Transfer charge image. According to the patent mentioned, the application roller acts with a scraper together, which removes excess developer material. The developer material consists of polar or non-polar liquids as well as from materials in the form of a dry powder. In addition, the Application roller in contact with the photoconductive surface.

The US-PS 3 772 ol2 describes a special development process, in which the application element for the developer is biased to a potential, which is essentially is equal to the maximum potential of the area carrying the latent charge image. The development is in this process achieved by making the surface of the applicator element sufficiently close to the surface with the electrostatic Charge image brings up, so that the developer, which is based on a polar liquid is drawn from depressions in the applicator element onto the surface carrying the charge image in order to produce a negative or Develop reverse image.

US Pat. No. 3,839,032 describes the use of applicator rollers which are in contact with a photoconductive, the latent

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Electrostatic charge image-bearing drum stand and which are transferred to the latter developer liquid in order to develop the charge image.

U.S. Patent 3,886,9oo discloses the possibility of using an applicator roll to form a "dynamic." Supply (dynamic pool) "or a meniscus for transferring a developer liquid to a latent electrostatic Charge image.

U.S. Patent 3,974,554 describes the use of an applicator roller which is formed with a pattern of spiral and convex Grooves and islands are provided for transferring a developer liquid to a latent electrostatic Charge image, the roller being in contact with the charge image.

US Pat. No. 3,991,711 describes the possibility of applying an electrically conductive ink to a roller with the aid of a roller transferring latent electrostatic charge image, the roller made of an electrically conductive elastomer exists and is in contact with the photoconductive surface.

The US-PS 4,021,586 describes the possibility of using an applicator roller, which is in a bath of a liquid Developer can be immersed and moved out of it. A coating electrode is provided in the bath, which makes it possible to electrically deposit toner particles from the bath onto the roller while they are moving located in the bathroom. The roller with the toner particles is then lifted out of the developer liquid and in Contact with the photoconductive, the latent electrostatic

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Brought charge image-bearing layer, which is provided as the outer surface of a rotating drum. It will the carrier liquid in the toner deposit on the The applicator roller is pushed back before it comes into contact with the photoconductive surface.

Object of the invention

Starting from the prior art, the invention is based on the object of a new method for developing a latent electrostatic charge image by means of a toner particles dispersed in a carrier liquid containing To indicate developer liquid, in which the difficulties and disadvantages of the known development process must be overcome and a copier suitable for carrying out this process must be specified *.

As far as the method is concerned, the object set is achieved according to the invention in that the moist and developed electrostatic charge image exposes electrical forces to induce further electrophoresis, wherein the electrical forces are in particular in the form of an electrical field generated by a field electrode or caused by a corona discharge device.

To carry out the method according to the invention has a copier according to claim 16 particularly proven.

In general, the invention is therefore concerned with a method and a device for producing copies on plain paper copiers using a

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liquid toner, with the development of the latent electrostatic Charge image on a photoconductive surface is controlled so that only the charged image areas of the photoconductive surface can be toned. A liquid developer is used, which has a higher one Contains toner concentration than is possible with the developer liquids used in conventional copiers is. In particular, a developer liquid is used in which the ratio of carrier liquid to toner particles or solids is chosen so that the position of the developer liquid on the toned image or the image areas of the same in the wet state a thickness between about 3 and 7 / am owns. The developer liquid has thereby an inert ^ like ζ .Β. a liquid hydrocarbon, which has a lower vapor pressure at ambient temperature possesses than the liquid hydrocarbons usually used as a carrier for copiers, which mit.einem liquid developer work, thereby reducing the evaporation of the carrier component of the liquid developer will.

According to the invention, an applicator roller is also used, which is located close to the photoconductive surface, but does not touch it. The applicator roller is driven with such a sense of rotation and at such a speed that the relative movement between the photoconductive surface and the outer surface of the applicator roller at the point where the two surfaces meet next come, is essentially zero. The gap width between the applicator roller and the photoconductive Surface area between about 38 and Io2 / µm. The application roller can be wetted with developer liquid in such a way that a film of the

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Developer liquid results. The amount of developer liquid on the application roller must be per unit area be uniform and regulated within narrow limits, depending on the gap width between the applicator roller and the photoconductive surface and depending on the conductivity of the developer liquid. If the thickness of the film on the applicator roller is too thick, the copies will be quite damp during if the film thickness is too low, the charge image is not properly toned. If the developer liquid has no has sufficient conductivity, then it does not jump over the gap to the photoconductive surface in sufficient Dimensions. If, on the other hand, the developer liquid has too great a conductivity, then it causes one partial discharge of the latent electrostatic charge image, so that a satisfactory electrophoretic development hindered and ultimately a poor quality of the copies is obtained. While previously conductive liquids were used to jump a gap to the photoconductive surface and the charge image to tone, the invention exploits the phenomenon of electrophoresis, which occurs on the photoconductive surface takes effect during and after the transfer of the developer liquid. The improvement achieved according to the invention lies in the fact that there are no skips during the transfer process "Columns of developer liquid are obtained which exactly match the shape of the latent electrostatic charge image correspond. Instead, only small amounts of the developer fluid, which roughly correspond to the field distribution, skip over of the electrostatic latent image correspond to the gap while the electrophoresis continues is after the developer liquid has overcome the gap and is deposited on the photoconductive surface.

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is hit. According to the invention, electrophoresis after the transfer of the developer liquid is made possible the achievement of sharply defined images, with the latent electrostatic charge image only during short time intervals exposed to small amounts of developer fluid is. This enables rapid operation of the copiers operating according to the invention and thus the generation a large number of copies within a given time interval, the number of copies being greater than in the known copiers. In addition, the copies obtained are sharp and essentially dry because only parts the photoconductive surface with the developer liquid be moistened. The amount of liquid present on the application roller per unit area can thereby be controlled be that the outer surface of the applicator roller with depressions of a given capacity. A scraper can be assigned to the application roller, which levels the amount of liquid in the wells. However, it has been found to be particularly advantageous to have a To use smooth application roller in connection with a stripping roller, which is in the same direction of rotation as the Application roller rotates. In this embodiment, the volume of liquid per unit area on the application roller can through Change in the speed of the stripping roller can be regulated within narrow limits.

Since light liquid hydrocarbons are usually dielectric are, the developer liquid in the invention Process a polar compound or a so-called charge aligner can be added to the To give a charge to toner particles. On the other hand, there is also the possibility of using such toner particles, or to produce the toner particles in such a way that

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that they have the correct polarity and the developer liquid give overall the required conductivity, so that this the gap between the applicator roller and can skip the photoconductive surface. However, the conductivity of the developer fluid is allowed not be so large that it partially discharges the latent electrostatic charge image after the transfer.

According to the invention, the electrophoresis after the transfer promoted the developer liquid with the help of a development or field electrode, which the fields of the 'latent electrostatic charge image intensified. Furthermore, the developed image can be transferred to a sheet-shaped carrier material, especially on normal paper, can be made even sharper by using the developed image completely flooded with light or with a suitable radiation, as in an earlier one Registration of the applicant (official file number P 29 39 850.3) is described. Such a post-exposure will not only promoted the transfer of the toner to the carrier material, but also the density of the image areas the carrier material increased.

On the other hand, electrophoresis after the transfer of the developer liquid also by a corona discharge device acting on the developed charge image are promoted whose polarity is opposite to that of the electrostatic charge image.

A decisive advantage of the method according to the invention is that the development of the charge images on the photoconductive surface using a liquid Developer in plain paper copiers

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or can be regulated that essentially only one Toning of the charged image areas of the electrostatic latent image takes place.

It is also an advantage of the invention that the application roller for the liquid developer itself acts as a developer electrode can serve.

It is also an advantage of the invention that the volume of liquid per unit area on the application roller can be regulated or controlled within narrow limits.

Furthermore, it is an advantage that according to the invention when Electrophoresis is used to develop a latent electrostatic charge image on a photoconductive surface takes place not only when the developer fluid is transferred, but also after this transfer has been completed «.

According to the invention it is also advantageous that for developing a latent electrostatic charge image a developer liquid can be used in which the proportion of solids or the toner particles opposite the carrier liquid is higher than was previously the case. There is also the advantage that a carrier liquid with low vapor pressure can be used.

It is also advantageous in an embodiment of the invention, that there is the possibility of dynamically regulating the volume of the developer liquid on the applicator roller.

It is also advantageous according to the invention that the applicator roller for transferring the developer liquid

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has a distance from the photoconductive surface with the latent electrostatic charge image and this not touched.

It is also advantageous that according to the invention a field electrode can be provided, which strengthens the field of the electrostatic charge image and thus the Promotes electrophoresis after the transfer of developer fluid. In a corresponding way, it is also advantageous when the electrophoresis after the transfer of the developer liquid by a corona discharge device is promoted.

Further details and advantages of the invention are explained in more detail below with reference to drawings, and / or are the subject of the protection claims. Show it:

Fig. 1 is a schematic representation of a photocopier for performing the invention Method with some parts shown in section;

Figure 2 is a partial side elevational view of the copier of Figure 1 as viewed from line 2-2 in this figure with an applicator roller and an associated scraper roller;

3 shows a side view similar to FIG. 2, from which it is clear that the applicator roller is from a drum with the photoconductive Layer is driven, with the doctor roller and its associated doctor being omitted;

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4 is a perspective enlarged schematic partial view of the lateral surface of a Applicator roller for carrying out the method according to the invention;

5 shows an enlarged partial cross section a stripping roller with hemispherical depressions, the cutting line being longitudinal taken on line 5-5 in Figure 1;

FIG. 5a shows a representation similar to FIG. 5 for a stripping roller with circumferential direction running grooves;

6 shows a partial plan view of a stripping roller according to FIG. 5;

6a shows a partial plan view of a stripping roller according to FIG. 5a;

7 shows an enlarged illustration of a partial plan view of a stripping roller with depressions in the form of axial grooves and

Fig. 8 is a schematic representation of a copier for performing a variant of Method according to the invention, with some parts similar to .in Fig. 1 again in Section are shown.

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Specifically, the copier shown in the drawing has a conductive drum 2 which is provided with a layer 4 of photoconductive material and which on with Discs 6 provided with openings are mounted, which in turn are non-rotatably connected to a shaft 8 by means of a wedge Io are, which can be driven counterclockwise, as indicated by the arrow A. The drum 2 and the Adjacent devices are arranged in a known manner in an opaque housing (not shown). The shaft 8 can be grounded or in a known manner by means of a DC voltage source (not shown) be biased to a desired potential. One as a corona discharge device trained charging device 12 is suitable on the passing parts of the photoconductive Layer 4 to generate a charge. If selenium is used as a photoconductor, then a charge becomes more positive Polarity generated. If the photoconductor has a zinc oxide a resin as a binder or an organic photoconductive material such as polyvinyl carbazole or the like, then the charge is negative.

After charging by the charging device 12, the relevant area of the photoconductive layer 4 runs on one Lens 14, which is fitted into the housing and with the help of which an image to be reproduced on the loaded photoconductive layer is projectable. Since a photoconductor is an insulator in the dark and a conductor in the light, the areas of the photoconductor on which light strikes can be discharged, whereby the charge over the conductive Drum 2, the disks 6 and the shaft 8 flows off. This results in 4 on the photoconductive layer a latent electrostatic charge image, its non-charged Areas have a potential which is around

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is about 8oo to 100oo V above the potential of wave 8, whereby the potential can fluctuate within wide limits in individual cases. A tank 16 made of insulating material is used for receiving a developer liquid 18. An applicator roller 2o, which is made of a conductive plastic, for example from N-Buna can exist is mounted adjacent to the photoconductive layer 4. N-Buna is known to be a synthetic one Rubber produced by the copolymerization of butadiene and acrylonitrile. The application roller can be made of a plastic or a synthetic resin or a metal. If the applicator roller 2o consists of a dielectric Synthetic resin, then thin lines of the latent electrostatic charge image are provided with a toner, large areas, however, are not. If a metal roller is used as the application roller, then toner is applied in a wide range of image areas, over areas high image intensity, however, arcing can occur, which leads to the affected areas horizontal white lines appear in the copy. N-Buna is beneficial in that its conductivity is in close Limits can be set and because it is resistant to hydrocarbon oils, which act as carrier liquids in the implementation of the invention Procedure are used.

The surface of the applicator roller 2o can be smooth or textured, i.e. provided with pits or the like be which are suitable to accommodate a certain volume of the liquid developer. Fig. 4 shows a section from a roller surface which is provided with cassette-shaped depressions, while FIGS. 5 and 6 Show surfaces that are provided with (hemispherical) embossments. FIGS. 5a and 6a also show

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Roller surfaces which are provided with annular grooves which run concentrically to the axis of rotation of the applicator roller 2o. FIG. 7 shows a section from a roller surface with parallel to each other in the axial direction Grooves.

The conductivity of the applicator roller 2o is important and the best results are obtained when the surface the roller is smooth and polished and when the roller material

7 9 has a resistance of 10 to 10 ohm-cm.

Optimal results with minimal sparking are obtained when the specific resistance of the roll material

8 8
is between 10 and 5x10 ohm-cm. As will be explained in more detail below, the specific resistance of the roll material is important.

According to the invention, a gap B is provided between the photoconductive layer 4 and the outer surface of the applicator roller 2o, which at its narrowest point - between the arrows in FIG. 1 - has a width or height between approximately 38 and Io2 to owns. Good results have been achieved with a gap width of around 50 μm.

In the method according to the invention, the developer liquid jumps from the applicator roller to the latent electrostatic charge image, since between the applicator roller and an electrostatic field is present in the photoconductive layer is. A breakthrough can occur in areas in which there is a high field strength, whereby the latent electrostatic charge image along the line of closest approach between the applicator roller and the photoconductive one Shift is discharged. The occurrence of such breakthroughs has been found to be dramatic

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Can be reduced if you have an applicator roller off weakly conductive material used. The conductivity can be regulated by using the N-Buna rubber or another hydrocarbon oil resistant synthetic resin powdered carbon particles are added to the material that makes up the applicator roller is made to give a certain conductivity.

The amount of liquid developer that is in the gap between the applicator roller and the photoconductor is also essential Layer is present. It has been shown that the volume of developer liquid at the surface

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the applicator roller between about 1.55x10 v-id 4.65x10 cm / cm should lie. A corresponding amount of liquid can be achieved if the depressions are on the lateral surface the applicator roller 2o are dimensioned accordingly. In this case, the applicator roller is simply known Way past a scraper (not shown), which ensures that the remaining in the wells Liquid amount is kept at a predetermined value. In this way it is ensured that a predetermined amount of developer liquid is available on the outer surface of the applicator roller in order to across the gap between the applicator roller and the photoconductive layer to develop the latent Electrostatic charge image to be transferred to the photoconductive layer.

• 4

The application roller is preferably driven at such a speed that its peripheral speed corresponds to the peripheral speed of the drum or the photoconductive layer. An exact match however, the peripheral speed is not required. It is essential that the relative speed

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between the applicator roller and the photoconductive layer is kept constant and does not change. The applicator roller can be driven at a slightly higher peripheral speed are used as the photoconductive layer bearing the electrostatic latent image. If it's too big However, if the peripheral speed of the application roller is excessive, there is a tendency that the electrostatic charge image is "flooded" with developer liquid. If, on the other hand, the application roller is running at too low a speed is driven, there is a risk that the latent charge image is toned too weakly.

According to Fig. 1, a stripping roller 22 is provided which is seated on a rotatable shaft 24 which is supported by a belt or a chain 26 can be driven, which runs over a pulley or a sprocket 28, which in turn is driven by a motor 3o adjustable in speed is driven. The stripping roller 22 rotates in the same direction of rotation like the applicator roller 2o. A wiper 32 removes excess developer liquid from the wiper roller 22 and keeps it clean. The stripping roller 22 is by means of rings 34 at a predetermined distance from the application roller 2o, with the distance C between about 25 and 127 Aim. The amount of liquid on the applicator roller should be in the range given above. Such an amount of liquid can be easily set by adjusting the speed of the squeegee roller 22 and the gap C between this and the applicator roller 2o adjusts accordingly. In the case of a small gap width, the stripping roller can be used at a lower speed work. In the case of a larger gap width, on the other hand, the stripping roller must be driven at an increased speed. Because the speed of the motor 3o is adjustable,

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a corresponding speed of the stripping roller can be set. At increased speed, the volume of developer liquid increases on the applicator roller so reduced that the latent electrostatic charge image on the photoconductive Surface is lightly toned and very dry. When the speed of the squeegee roller is too fast is decreased, on the other hand, the images are quite wet. The speed of the stripping roller should therefore be set in this way that there is the correct volume of developer liquid on the applicator roller. The corresponding The speed of the stripping roller is between 100 and 2oo rpm and is of the gap width B between the applicator roller and the photoconductive surface and the developer liquid used in the individual case. An applicator roller 2o with a smooth surface forms in connection with a stripping roller that can be driven at a variable speed a particularly flexible combination, the one-number of advantages. In particular, the amount of toner on the applicator roller can be easily regulated. Also will the application roller 2o is also kept clean by a stripper 36, which rests against the surface of the application roller 2o. In the case of a textured surface of the applicator roller 2o, on the other hand, the volume of developer liquid is per Area unit is fixed and there is no setting option for different properties to take into account the developer liquid. aside from that there is a certain tendency for residues to accumulate in the depressions of the roller surface, which result in a Change the available volume of developer liquid on the surface of the applicator roller 2o lead.

As FIG. 1 shows, the applicator roller 2o can be driven by a motor 38 with variable speed via a chain 4o and a sprocket 39 be driven so that the difference in

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the peripheral speeds of the applicator roller 2o and the photoconductive surface 4 is close to 0 (the drive can also be done via a belt and a pulley) If you drive the applicator roller 2o at a higher speed, then more developer liquid is available for the development of the latent electrostatic charge image posed. If, on the other hand, you let the application roller run a little slower, then the gap B during a predetermined time interval a smaller amount of developer liquid transported to the electrostatic Develop charge image. When using an applicator roller with a textured surface, the speed control enables for the applicator roller 2o an adjustment to different developer liquids and changes in the capacity of the wells resulting from the accumulation of debris in them.

The bias of the applicator roller to positive or negative values compared to the reference potential can be set on a Adjust potentiometer circuit 42 · whose tapping via a conductor 44 is connected to the shaft 46 of the applicator roller 2o.

It is normally best if the photoconductive layer 4 and the applicator roller 2o operate at the same peripheral speed to run. This condition can easily be achieved by the construction shown in FIG. 3. According to FIG. 3, the applicator roller 2o is provided with flanges 21 at both ends. These flanges fit together photoconductive surface 4 and are rotatably connected to the applicator roller 2o. The applicator roller 2o has as mentioned a shaft 46 and is isolated from earth, so that the bias on the shaft 46 by the potentiometer circuit 42 can be set. the

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Friction between the flanges 21 and the photoconductive surface 4 against which the flanges 21 rest leads to that the difference between the peripheral speeds of the applicator roller and the photoconductive layer is essentially becomes zero and is in any case constant.

According to FIG. 1, the application roller 2o can be driven to rotate independently of the photoconductive layer 4. In detail, the shaft 46 of the applicator roller 2o carries at its ends disks 5o, which with respect to the inner Bearing rings 52 are set by ball bearings, the outer bearing rings 54 of which are supported on the photoconductive surface, as is clear from FIGS. 1 and 2. The shaft 46 passes through the ball bearings 47, which are loose on the machine frame 51 are supported and carries a sprocket 53 (or a pulley), which by a chain 4o (or by a belt) can be driven. 'Springs 49 between the bearings 47 and the machine frame 51 preload the outer bearing rings 54 against the photoconductive layer 4. As stated above, the difference may be in the peripheral speed of the applicator roller and the photoconductive layer by adjusting the speed of the motor 38 can be adjusted.

In a corresponding manner, the stripping roller 22 is spaced from the applicator roller with the aid of a ball bearing 2o held, the ball bearing having outer bearing rings 34 and inner bearing rings 33, which are on end regions Reduced diameter of the shaft 24 of the stripping roller 22 sit, with an end portion of the shaft 24 the machine frame 51 extends through and on the outside of the same carries a sprocket 53 (or a pulley). The motor 3o drives the sprocket 29, which the chain

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26 drives, which runs on the shaft 24 via the sprocket 23. The stripping roller 22 is from the motor 3o im can be driven in the same direction of rotation by running the applicator roller 2o, at any desired speed.

Fig. 1 also shows that the tank 16 is provided with a line 15 which is filled with a supply of developer liquid (not shown) is connected, and through which the developer liquid is supplied to the tank 16. Of the The level of the developer liquid in the tank 16 can be monitored by means of a suitable fill level monitor (not shown). be kept at a predetermined value. Fig. 1 also shows that the applicator roller 2o is mounted so that you The lower part is immersed in the developer liquid in the tank 16, so that the applicator roller 2o developer liquid from the tank 16 in the manner described above to the latent electrostatic charge image adjacent to it can transfer on the photoconductive layer.

The composition of the developer liquid is essential. If the developer liquid has too high conductivity, then it becomes the latent electrostatic Partially discharged charge image. If, on the other hand, it has too low a conductivity, then will Insufficient amount of developer fluid across the gap between applicator roller and photoconductive layer transferred so that an underdeveloped electrostatic charge image is created. The one used according to the invention Developer liquid differs from the usual developer liquids in that the toner concentration in the developer liquid is greater than before and that the carrier liquid is a hydrocarbon oil has a lower vapor pressure than the known developer liquids. Most of them so far

030035/0867 -37-

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February 19, 198ο - 37 -

k - 176

Isopar-G is used as the carrier liquid. This liquid comprises isoparaffinic hydrocarbons of a narrow range having an initial boiling point of about 160 ⁰ C and a drying end or point of about 174 C, the flash point is above about 38 ° C. The isoparaffin hydrocarbon under consideration, when exposed to the atmosphere, evaporates completely within 22oo s, according to measurement method 11 of the test conditions of the Federation of Societies for Paint Technology. According to the invention, the aim is to reduce the evaporation of the hydrocarbon carrier liquid and to use a higher-boiling isoparaffin hydrocarbon such as Isopar-M, which has a boiling range between about 21o and 252 C and a low vapor pressure and has a flash point of about 77 ° C lies. Only 10% of such an isoparaffin hydrocarbon evaporate in a time interval of 35oo s if the measurements are carried out according to the measurement method 11 given above. The isoparaffin hydrocarbon under consideration is essentially a light mineral oil. Other light mineral oils, such as those sold under the trade names "Marcol 52" and "Marcol 62", are highly refined white mineral oils that are free of unsaturated compounds and have a high degree of chemical stability. The mineral oils considered are odorless and tasteless and meet all standards for internal, medical and cosmetic use. The mineral oils are produced, for example, by Humble Oil and Refining Company, USA, and have a viscosity of 51 or 61 Saybolt seconds at a temperature of 37.8 ° C. The mineral oils mentioned also meet the requirements of

030035/0867 ~ ³⁸ ~

A 43 947 b -

February 19, 1980 - 38 - _{9i> nc} n _ö1

k - 176 3UUb / oil

FDA standard 124.1146. "Marcol 52" has a specific gravity of 0.827 _f at a temperature of 15.6 ° C. while "Marcol 62" has a specific gravity of 0.834 at this temperature. The mineral oils mentioned above are used according to the invention as carrier liquid into which toner particles are introduced with a high concentration. The latent electrostatic charge image is developed by electrophoresis, that is, in that the toner particles migrate through the carrier liquid to the latent electrostatic charge image, which represents a charge distribution on the photoconductive layer that corresponds to the He11 / dark image projected onto the charged photoconductive layer 4 is equivalent to. The carrier liquids mentioned have a very low vapor pressure, and the small amount of carrier liquid which passes the gap between the applicator roller and the photoconductive layer contains the toner particles which develop the electrostatic charge image by electrophoresis. During the development process, droplets of the toner liquid pass the gap and arrange themselves - roughly - according to the field distribution of the electrostatic image. This electrophoresis continues after the gap has been passed, with a small amount of the carrier liquid remaining on the photoconductor and enabling electrophoresis. When the developed image is transferred to a carrier material such as paper, the carrier liquid immediately disperses into the paper so that the image on the paper is essentially dry despite the fact that the image on the photoconductor is moist does not smear. The relevant details are explained in more detail below. At this point, it should be noted that carrier liquids are described in greater detail above

030 0 3 5/0867 ~ ³⁹ ~

A 43 947 b

February 19, 198ο -39- λ η η c <7 α ι

k - 176 3UUb / Q I

explained type are preferred according to the invention, but that in principle with any suitable dielectric liquid can be worked, which does not dissolve the toner particles.

In the toner of the present invention suitable for electrophoresis, solid toner material is used in an amount of 5 to 3o wt .-%, based on the weight of the carrier liquid, used. Liquid hydrocarbons are dielectric and would fill the gap between the applicator roller and Do not skip the photoconductive layer. For this reason the developer liquid must have a polar compound, for example a so-called charge director are added so that by the method according to the invention with a gap between the applicator roller and photoconductive layer can be worked. Suitable charge aligners are, for example, in US-PS " 3,669,886 described and represent polar compounds in the serving as the carrier liquid hydrocarbon are soluble and lead to a charge of the microfine pigment or toner particles, so that these with Development process can migrate due to the phenomenon of electrophoresis. When the photoconductive layer can be positively charged, a charge aligner should be used that is capable of the toner particles to give a negative polarity. If the photoconductive layer can be charged negatively, on the other hand, a charge aligner that gives the toner particles a positive polarity should be used can. The use of charge aligners can be dispensed with if the pigment or toner particles make the developer liquid conductive by itself. It is known that long chain polymers

030035/0867 " ⁴ ° -

A 43 947 b

February 19, 198ο - 4o - one "7ö1

k - 176 3UUb / Q I

be partially destroyed in a ball mill and take on a charge. Long chain polymers can also do this be provided with a charge to dye selected polymers or a selected one during the polymerization Adds monomer. When using such polymers as toner material, the carrier liquid itself remains dielectric, however, the liquid developer becomes conductive as a whole through the charged toner particles. The conductivity The developer liquid represents a critical value for a given gap width. With a larger gap width an increased conductivity is required. For example, if the gap width is about 5oyum, then A conductivity between about 5o, ooo and 1, ooo, ooo pS is required. If the conductivity is too high, it will partially discharged latent electrostatic charge image. On the other hand, if the conductivity is too low, then a sufficient amount of developer liquid does not jump over the gap, so that the latent electrostatic charge image is not developed properly.

Following the transfer of the developer liquid from the applicator roller to the photoconductive layer the electrophoretic evolution that occurs when skipping started. Those toner particles that are still outside charged at this point Areas of the latent electrostatic charge image are located, move into these charged areas into it. These electrophoretic processes take place at an embodiment of the method according to the invention accelerated by the fact that a field electrode 6o is provided, which by means of a direct current source, for example with the aid of the battery 62. * ■ is. The bias on the developer or field electrode

030035/0867

A 43 947 b

February 19, 198ο -41- onoßTöl

k- 176 JUUb IQ

has the same polarity as the charge of the photoconductive layer or the latent electrostatic charge image. If the photoconductive layer is made of selenium, this charge is positive. If an inorganic photoconductor or cadmium sulfide is used, the polarity or charge is negative. It has been shown that the grounding of the field electrode 6o leads to a reference potential, welc hes results in an effective support of the electrophoresis even in the absence of a bias voltage. The gap D between the field electrode 6o and the photoconductive layer 4 should be as small as practical. The function of the field electrode 6o is to project the electric field of the electrostatic charge image at a greater distance from the surface of the photoconductor. However, the gap D should not be so narrow that the field electrode contacts the photoconductive layer. Since the film thickness of the developer liquid transferred to the photoconductive layer 4 of the drum 2 is never greater than about 0.25 to 0.5 μm, there is no contact between the field electrode 6o and the latent electrostatic charge image on the photoconductive layer 4 when the field electrode 6o is applied at a distance between about 3o5 and 38IyUiIi from the photoconductive layer 4. It should also be noted that the distance between the photoconductive layer 4 and the field electrode 6o, ie the width of the gap D, should be at most 10 times the thickness of the photoconductive layer. With a greater distance, the improvement in resolution brought about by the field electrode is reduced. The optimal distance is equal to the thickness of the photoconductive layer. Of course, this distance cannot be maintained if the photoconductive layer 4 on the drum 2 _{/ is,} as usual, very thin. The function of the

-42-030035 / 0867

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February 19, 198o - 42 -

k - 176

field electrode used according to the invention is of the Function of classic developer electrodes different in development systems »The function of the field electrode is different So it depends on the function of the applicator roller, which according to the invention is used for the transfer of the developer liquid acts as a developer electrode to the photoconductive surface. The purpose of the developer electrode is in the known systems in preventing toner particles from also in the background areas of the charge image deposited on the photoconductive layer. Of course, this only happens when the developer fluid in contact with both the electrostatic image on the photoconductor and the developer electrode stands. In the method and apparatus according to the invention, the electrophoresis takes place mainly after the transfer instead of. The developer electrode amplifies the electric fields, which are normally small fringe fields are at the edges of the charged areas of the electrostatic image. In the method according to the invention provides the field electrode has a voltage with the same polarity as the charge on the photoconductive layer, but with one Value which is higher than the highest potential of the electrostatic latent image. With the invention Developer electrode field distributions are created on the surface of the photoconductor, which increase the mobility promote the toner particles in the small amount of developer liquid that is on the photoconductive layer transferred to the drum and is outside of the charged image areas. In this way it becomes possible to cheaply and efficiently continue electrophoresis on the photoconductor after the transfer of the toner material so that the development process may take longer than usual. The developer electrode 6o

030035/0867 ~ ⁴³ ~

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February 19, 198ο -43- 3QQ 6) 7

should be as long as possible, as this enables electrophoresis to be continued to the greatest possible extent will ultimately result in a more sharply developed image.

A lamp 64 for a low level of illumination, as for example in an earlier application of the applicant (Official file number P 29 39 850.3) is described, is arranged so that the photoconductive layer 4 with the developed image is flooded with light after passing the amplification or field electrode 6o. To this Not only does one get sharper contours of the image by discharging the background areas of the image, but also also a more complete transfer of the developed image to a carrier, for example a paper material, when transferring the image.

If a mineral oil with a higher boiling point is used, the result is a moist, developed one on the photoconductor Image although the amount of developer liquid is small and the humidity is weak. A carrier material such as paper 66 is fed by rollers 68 to a pressure roller 7o. It was found that using of the pressure roller 7o, the moist image can be transferred from the surface of the photoconductor to the paper 66, since this represents an 'absorbent carrier. The transfer is improved by a suitable prestress 7o acting on the pressure roller. -If the backing material is one is a transparent film made of a synthetic resin which is not absorbent, it becomes a corona discharge device 72 is provided, which can charge the back of the carrier material to thereby transfer the image to effect from the photoconductive layer on the carrier material. The polarity of the on the back of the carrier

030035/0867 -44-

A 43 947 b

materials applied should be the same as that of the charge of the developed electrostatic image. When using selenium as a photoconductor, this is Charge a high positive charge. When using cadmium sulfide or an organic photoconductor, this charge is a negative charge. The developed image will by charging from the rear side of the photoconductive layer onto the sheet-shaped carrier material transfer. A deflector sheet 74 ensures that the sheet-shaped carrier material 66 after passing through the Pressure roller 7o and optionally the corona discharge device 72 are lifted from the drum and take-off rollers 76 is fed from which it is transported to a collecting basket, a sorting device or the like will. In order to keep the surface of the photoconductive layer 4 clean, there is also a cleaning roller 78 is provided, which keeps the drum surface clean and a scraper 8ο on the running direction of the drum follows, which completes the cleaning.

In the modified embodiment of a "copier according to the invention, which is shown in Fig. 8, the developer liquid is first again with the help of Application roller 2o applied to the photoconductive layer 4. The developed, still moist image then becomes the The action of a corona discharge device 82 which generates a charge, the polarity of which is the same the charge of the electrostatic image is opposite to the electrophoresis effect that occurs in the transfer the developer liquid from the application roller on the photoconductive layer 4 has started to intensify, It has been found that significantly sharper copies are obtained in this way.

-45-

030035/0867

A 43 947 b

February 19, 198ο -45-

_k _ ₁₇₆

In the copier according to FIG. 8, the transmission takes place of the developed image onto a sheet of copy material 66, by means of feed rollers 68 in the nip is fed between the photoconductive layer and a transfer roller 84. The transfer roller 84 is made made from a deformable conductive material, for example from N-Buna rubber, to which a sufficient amount of carbon particles was added to give it the desired level of conductivity. With help a suitable voltage source, for example with the aid of a battery 88, is also provided with a bias potential the shaft 86 of the transfer roller 84 is applied. The interaction this bias and the pressing force of the transfer roller 84 results in the developed image is transferred from the photoconductive layer 4 to the sheet of copy material 66, which is then again from the Pick-up 74 lifted from the drum surface and finally is fed in a known manner to a collecting basket or the like.

In operation, the drum 2 with the photoconductive layer 4 in the direction of arrow A with the aid of a motor or other suitable drive device (not shown) driven to a rotary movement. When a copy is made is to be, then the photoconductive layer 4 is charged with the aid of the charging device 12 and then with exposed to an image of the document to be copied, which is projected by the lens 14 onto the photoconductive layer will. In this way a latent electrostatic charge image is obtained. The applicator roller 2o runs with one such speed that there is essentially no relative movement between the photoconductive layer 4 and the Application roller 2o results. In this case, a bias voltage can be applied to the applicator roller 2o in order to reduce the amount of developer liquid to reduce which in the transmission of the

030035/0867

-46-

A 43 947 b ■ *

Developer liquid reaches the background areas of the latent electrostatic charge image. The application of such a bias voltage is, however, not as essential for subsequent electrophoresis with regard to the methods used according to the invention as in previously known copiers operating with a liquid developer. Furthermore, the applicator roller 20 is kept at a distance from the surface of the photoconductive layer 4, so that the gap B results, which preferably has a width of 50 ma . The wiper roller 22, which in turn is provided with a wiper 32, is driven by the motor 3o at the correct speed and runs in the opposite direction of rotation to the direction of rotation of the applicator roller 2o, so that the amount of developer liquid on the applicator roller 2o is set so that a properly developed image with the desired contrast is obtained. The applicator roller 2o is immersed in the tank 16 with the developer liquid 18, its associated scraper 36 keeping it clean. The applicator roller 2o can, if so desired, be driven independently with the aid of a motor 38 at such a speed that the relative speed between the applicator roller and the photoconductive layer is different from zero, the peripheral speed of the applicator roller 2o being higher than that of the photoconductive layer Layer 4. The developer liquid is produced, as described, using a liquid carrier with a low vapor pressure and contains a solid concentration which is higher than that of conventional developer liquids. The conductivity of the developer liquid is further controlled by the addition of polar compounds or charge aligners within narrow limits in such a way that its conductivity is high enough to jump over the gap

030035/0867 ~ ⁴⁷ -

A 43 947 b

February 19, 198ο - 47 - _onnß « _ö1

k - 176 3UUb JQ I

can, but not so large, that the latent electrostatic charge image on the photoconductive layer is partially is discharged. After the developer liquid, the gap between the applicator roller and the photoconductive layer has skipped, the image is then developed by electrophoresis effects that follow the transfer process, in the course of which it also begins some part of the development is going on. In order to intensify the electrophoresis effects, according to the invention uses a field electrode 6o which is biased with a bias of the same polarity as that of the latent Has electrostatic charge image, and arranged as close as possible aa of the photoconductive layer without touching it.

The field electrode 6o intensifies the electric field, which would normally be a weak fringing field, at the edges of the image areas and supports electrophoresis by increasing the mobility of those toner particles that in the carrier liquid outside the charged image areas are located.

When the developed image has passed the field electrode 6o, the background areas are fainted by one Discharge lighting with lamp 64. This full-surface illumination of the developed image results overall a sharper image, so that an image with a higher information density is then transferred to a sheet-shaped carrier material, e.g. paper, can be transferred. If paper or some other absorbent. Backing material used then a transfer of the slightly moist image is effected simply by pressing it on. The small amount of remaining carrier liquid '- becomes old from the paper

-48-

Ü3ÜC35 / Ü-37

BAD OF «®» lö * jL

A 43 947 b

February 19, 198ο - 48 - O Π Cl ß 7 ö

k - 176 3-QQ6 / 8

or the like is rapidly absorbed so that a dry copy is obtained that does not require heat treatment needs to be dried.

The copier according to the invention shown in FIG. 8 works essentially in the same way as the copier according to FIG 1, up to the point in time at which the photoconductive layer 4 passes the applicator roller 20. After this However, when the developer liquid is applied, the developed image is now subject to the action of a corona discharge device 82 exposed, which causes the creation of a much sharper image. Then lead the rollers 68 apply a sheet of copy material 66 to the nip between the photoconductive layer 4 carrying the developed image and the transfer roller 84. Below the transfer roller, the image is then under the combined influence of the pressure of the transfer roller 84 and a bias voltage applied thereto by means of the battery 88 to the sheet of copy material 66 transferred, which is then lifted off the drum and output from the "copier.

From the foregoing description it can be seen that the objects of the invention are achieved. Indeed, after the method according to the invention allows the use of liquid toners in plain paper copiers, the Development of a latent charge image on a photoconductive surface is controlled so that substantially only the charged image areas of the latent electrostatic charge image are toned without wetting the uncharged areas or the background areas.

-49-

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February 19, 198ο -49- 30067

Furthermore, the present invention provides an improved copier for carrying out the improved development process indicated in which the copier has an applicator roller with the help of which the liquid developer is transferred across a gap onto the latent charge image will. The application roller are assigned metering devices with the help of which the application roller for the development of the latent electrostatic charge image separated therefrom by a gap Liquid volume is controlled statically or dynamically. In detail, the static dosage is in the way achieved that the applicator roller on its outer surface

Wells are provided with a predetermined volume per unit area, interact with a scraper blade leaves. The application roller can also be a smooth roller, which then in conjunction with a Stripping roller is used, which is in the same direction of rotation and rotates at a controlled speed to dynamically adjust the volume of liquid per unit area on the applicator roller to regulate.

The inventive method is carried out so that the electrophoresis not only during the transfer of the developer liquid takes place from the applicator roller to the photoconductive surface, but mainly after this Transfer is brought about. According to the invention, developer liquids are used which have a higher Contained proportion of toner particles in the carrier liquid than was customary up to now, with a dielectric carrier liquid also being used, which is a lower one than the previously usual vapor pressure.

030035/0867

A 43 947 b

February 19, 198ο - 5o -

k - 176

In the method according to the invention, the conductivity of the developer liquid is controlled by using toner particles which have polar properties,
or by using so-called charge aligners. The conductivity of the developer liquid as a whole is selected so that it is high enough to enable the gap present according to the invention to be jumped over, but too low to partially discharge the latent electrostatic charge image. With the help of a field electrode or
a corona discharge device used after the first toning, the field of the latent electrostatic charge image is further intensified according to the invention and a
Electrophoresis is promoted following the transfer of the developer fluid.

Finally, it should be noted that only preferred exemplary embodiments have been described above,
however, to which the invention is in no way limited. Rather, based on the exemplary embodiments, the person skilled in the art has numerous possibilities for changes and /
or additions to bids without having to leave the basic idea of the invention.

030035/0867

Claims (1)

Claims / Ί., Method of developing a latent electrostatic Charge image with a developer liquid which consists of a dielectric carrier liquid with distributed therein charged toner particles, thereby characterized in that one transfers to the latent electrostatic charge image developer liquid to the charge image by electrophoresis of the charged To develop toner particles and then that moist and developed electrostatic charge image to bring about an additional electrophoresis exposed to electrical forces. 2. The method according to claim 1, characterized in that the moist and developed electrostatic charge image exposing it to an electric field which has the same polarity as the charge on the electrostatic image owns .. 3. The method according to claim 1, characterized in that the moist and developed charge image is additional exposed to electrical forces in the form of a corona discharge, which has the opposite polarity as the charge of the latent electrostatic charge image. 030035/0867 " ² " A 43 947 b k - 176 4. The method according to any one of claims 1 to 3, characterized in that that the developed charge image is transferred to a sheet-shaped carrier. 5. The method according to any one of claims 1 to 4, characterized in that that a developer liquid with a conductivity between So.ooo and l.ooo.ooo pS used. 6. The method according to any one of claims 1 to 5, characterized in that that the developer liquid on the surface of the latent electrostatic charge image transmits over a gap that has a gap width between about 38 and 76 Aim. 7. The method according to any one of claims 1 to 6, characterized in that that the developer liquid from a -3-3 Layer with a volume of about 1.55x10 to 4.65x10 3 2 cm / cm transfers. 8. The method according to any one of claims 1 to 7, characterized in that that the developed electrostatic charge image after the action of the additional electrical Forces fully illuminated in order to discharge its background areas. 9. The method according to claim 5, characterized in that there is used a developer liquid, which from liquid hydrocarbons and toner particles dispersed therein and a small amount of a polar compound exists, with the help of which the toner particles can be charged are to give the developer liquid its conductivity. 030035/0867 " ³ " A 43 947 b February 19, 198ο -3- onnßTQ k - 176 3UUb / 0 lo. Method according to one of Claims 1 to 9, characterized in that that one transfers the developer liquid from a carrier having a resistance between 10 and G
10 ohm-cm. 11. The method according to claim lo _f, characterized in that the layer thickness of the developer liquid on the carrier is kept at a value between about 25 and 50 .um. 12. The method according to any one of claims 1 to 11, characterized in that the latent electrostatic Generated charge image on a moving photoconductive surface and that one the developer liquid transfers with the help of a moving carrier element, the surface of which is essentially with moves at the same speed as the photoconductive surface. 13. The method according to claim 12, characterized in that the layer thickness of the developer liquid sets on the carrier element to a predetermined value which is a function of the gap width between the photoconductive layer and the surface of the carrier element, the conductivity of the developer liquid and the potential of the electrostatic latent image and is chosen so that the developer liquid skips the gap. 14. The method according to claim 13, characterized in that that the carrier element for the developer liquid is a transmission element that can be driven to rotate used, which is driven at such a speed that its surface area with the the same or a slightly higher speed at which the photoconductive surface moves emotional. 030035/0867 —4 - A 43 947 b February 19, 198ο - 4 - 3QQ8781 15. The method according to claim 13, characterized in that the layer thickness of the developer fluid is kept at the specified value by dynamic dosing. 16. A copier for the electrophotographic production of copies according to the method according to any one of claims 1 to 15 with a photoconductive layer, with a charging station for electrostatic charging of the photoconductive layer Layer, with an exposure station for exposing the charged photoconductive layer with a light / dark image the document to be copied to form a latent electrostatic charge image on the photoconductor, with a developer station for developing the latent electrostatic charge image into a visible one Charge image by means of a liquid developer and with a drive device for bringing about a relative movement of the photoconductor opposite the charging station, the exposure station and the developer station, characterized in that a field electrode (6o) is provided, with the help of which the developed electrostatic Charge image can be exposed to an electric field that potential generating devices (62) are provided are, with the help of which a potential can be applied to the field electrode (6o) which has the same polarity how the potential of the electrostatic charge image possesses and that the drive devices are designed in such a way are that the developed electrostatic charge image can be moved past the field electrode with their help. 17. Copier for the electrophotographic production of copies according to the method according to one of claims 1 to 15, with a photoconductive layer, with a 0 3003 5/0867 -5- A 43 947 b February 19, 198ο - 5 - 3008781 k - 176 Charging station for electrostatic charging of the photoconductive Layer, with an exposure station for exposing the charged photoconductive layer, with a light / dark image of the document to be copied for the formation of a latent electrostatic charge image on the photoconductor, with a developer station for developing the latent electrostatic charge image into a visible charge image by means of a liquid developer and with drive devices for bringing about a relative movement of the photoconductor compared to the charging station, the exposure station and the developer station, characterized in that one Corona discharge device (82) is provided that potential generating devices are provided with whose help a potential can be generated for the corona discharge device (82) which is the opposite Polarity as the polarity of the developed electrostatic charge image, and that the Drive devices are designed such that the developed electrostatic charge image on the photoconductive layer (4) on the corona discharge device can be moved past. 18. Copier according to claim 16 or 17, characterized in that a developer application roller at the developer station (2o) is provided and that spacer devices (54) are provided around the photoconductive Keep the surface (4) and the applicator roller (2o) at a minimum distance between about 38 and Io2 do. -6- 030035/0867 A 43 947 b - 19. Copier according to one of claims 16 to 18, characterized characterized in that transmission devices (66 to 76; 66 to 88) are provided / with their Help the developed electrostatic charge image can be transferred to a copy material (66). 20. Copier for electro-photographic production of copies, in particular for carrying out the method according to one of claims 1 to 15, with a conductive support that can be driven to rotate, with a photoconductive support provided on the support Layer, with charging devices for charging the photoconductive layer and with exposure loading, directions for exposing the charged photoconductive layer with a light / dark image of a to be copied Document for generating a latent electrostatic charge image, characterized in that that an applicator roller (2o) which can be driven to rotate is provided for a developer fluid is that drive devices (38, 39, 4o, 53) are provided, with the help of which the applicator roller (2o) and the photoconductive layer (4) can be driven synchronously in such a way that the relative speed is between photoconductive layer (4) and applicator roller (2o) is essentially zero, that fastening devices for the applicator roller (2o) are provided, with the help of which a value between about 38 and Io2 xm can be set for its minimum distance from the photoconductive layer (4) the applicator roller is immersed in that a stripping roller (22) is provided which is mounted close to the applicator roller (2o) without closing it 0 30035/0867 -7- A 43 947 b February 19, 198ο - 7 - of \ r \ rl oil k-176. 3uub / ο ι touch, and that second drive devices (23 to 3o) are provided, with the help of which the stripping roller (22) to adjust the layer thickness of the developer liquid on the applicator roller (2o) with the same direction of rotation as the applicator roller (2o) can be driven. 21. A copier according to claim 2o, characterized in that a scraper (36) for cleaning the applicator roller (2o) is provided, which at one in the direction of rotation behind the gap for the transfer of the developer liquid engages lying area of the applicator roller (2o). 22. Copier according to claim 2o, characterized in that a scraper (32) for cleaning the stripping roller (22) is provided, which on the stripping roller (22) on one in the direction of rotation in front of the metering gap (C) the area of the stripping roller lying between the applicator roller (2o) and the stripping roller (22) (22) attacks. 23. Copier according to claim 2o, characterized in that the second drive devices for the stripping roller (22) are designed as drive devices with variable speed. 24. Copier according to claim «2o, characterized in that that the stripping roller (22) at its ends with the setting of a metering gap (C) 'wipe the stripping roller (22) and the applicator roller (2o) serving · flanges (34) is provided, which are located on the surface support the photoconductive layer (4). 030035/0867 -8th- A 43 947 b February 19, 198ο -8- ο Π Π R 7 & k - 176 .3UUb / 0l 25. Copier according to claim 2o, characterized in that that the material of the applicator roller (2o) has a resistance 7 9
stood between 10 and 10 ohm-cm. 26. Copier according to claim 2o, characterized in that the applicator roller (2o) with on its surface Depressions is provided. 27. A copier according to claim 26, characterized in that the volume of the depressions is between approximately 1.5 5 xlO ~ ³ and 4.6 5 xlO ~ ³ cm ³ per cm ² . 28. Copier for electro-photographic production of copies, in particular for performing the method according to one of claims 1 to 15, with a conductive support, with a photoconductive layer provided on the support, with charging devices for charging the photoconductive layer and with exposure devices for exposing the charged photoconductive layer with a light / dark image an "original to be copied to produce an electrostatic latent image, thereby characterized in that movable application devices (2o) for transferring developer liquid the photoconductive layer (4) are provided that drive devices (38, 39, 4o, 53) are provided are, with the help of which the application devices (2o) and the photoconductive layer (4) can be driven in such a synchronous manner are that the relative speed between photoconductive layer (4) and application devices (2o) it is essentially zero that fastening devices are provided for the application devices (2o) with their help for their minimum distance 030035/0867 A 43 947 b of the photoconductive layer (4) a value between about 38 and Io2, in order to be adjustable that devices for applying developer liquid to the application devices (2o) are provided that Dosing devices for adjusting the thickness of the film of the developer liquid on the application devices (2o) are provided that a field electrode (6o) is provided which is adjacent to the surface of the Photoconductive layer is arranged so that it is a developed by applying the developer liquid exposing the electrostatic charge image on the photoconductive layer (4) to an electric field, and that potential generating devices (42, 44) are provided with the aid of which a potential of the Field electrode (6o) can be brought about that has the same polarity as the potential of the electrostatic charge image owns. 29. A copier according to claim 29, characterized in that the metering devices eiie stripping roller (22), that spacing devices (34) are provided, with the aid of which a predetermined distance between the stripping roller (22) and the applicator devices (2o) is adjustable _f and that second drive devices (23 to 3o) are provided, with the aid of which the stripping roller (22) can be driven with such a sense of rotation that its surface areas adjoining the application devices (2o) move in the opposite direction as the application devices (2o). -lo- 030035/0867 A 43 947 b February 19, 198ο - Io - 3o. Copier according to claim 28, characterized in /: that the movable conductive carrier is designed as a drum (2) which can be driven to rotate, on which a photoconductive layer (4) is provided that the applicator devices as an applicator roller (2o) are formed, the material of which has a resistance 7 9 between 10 and 10 ohm-cm that the applicator roller (2o) is mounted in such a way that it is able to rotate about a parallel to the axis of rotation of the drum (2) Axis is drivable ^ and that the metering devices are designed such that the film thickness of the developer liquid on the applicator roller (2o) on a Volume between about 1.55 x 10 ~ and 4.65. xlO cm is adjustable per cm. 31. Copier according to claim 3o, characterized in that the metering devices by depressions on the The outer surface of the application roller (2o) and a scraper cooperating with this outer surface are formed are. 32. copier according to claim 3o, characterized in that the metering devices have a stripping roller (22) have that spacer devices (34) are provided, with the help of which the stripping roller (22) in one predetermined distance from the applicator roller (2o) can be determined and that the stripping roller with the help of the second drive devices (23 to 3o) can be driven in the same direction of rotation as the applicator roller (2o). 33. copier according to claim 3o, characterized in that lighting devices (64) are provided, with the help of which the developed electrostatic 030035/0 867 A 43 947 b February 19, 198ο -11- λ η η e <Ψ ο 1 k - 176 OUÜb / O I Charge image, after it has been exposed to the field of the field electrode (6o), can be illuminated over the entire area. 030035/0867