EP1290504A2

EP1290504A2 - Device and method for cleaning and regenerating an image support during electrographic printing or copying using liquid inks

Info

Publication number: EP1290504A2
Application number: EP01947328A
Authority: EP
Inventors: Martin Berg; Martin Schleusener; Volkhard Maess
Original assignee: Oce Printing Systems GmbH and Co KG
Current assignee: Canon Production Printing Germany GmbH and Co KG
Priority date: 2000-05-31
Filing date: 2001-05-31
Publication date: 2003-03-12
Also published as: US6876833B2; WO2001092968A2; US20030170057A1; DE10027203A1; WO2001092968A3

Abstract

The invention relates to a device for cleaning an image support by removing the remnants of color images. In order to ink the latent image on a latent image support (12), droplets (50) are transferred from a liquid layer (48, 72) to the surface of the latent image support (12) while passing through an air gap (L). According to the invention, the cleaning device is arranged on the periphery of the image support and removes the remnants of the ink that remain after transferring the image, which is inked with a liquid ink, from the surface of the image support (12, 14).

Description

Device and method for cleaning and regenerating an image carrier in electrographic printing or copying using liquid colorants

The invention relates to a device and a method for cleaning an image carrier from color image residues, in particular for cleaning in electrographic printing or copying using liquid colorants. Furthermore, the invention relates to a device and a method for regenerating an image carrier, which are each adapted to the use of liquid colorants.

Known devices for electrographic printing or copying use a process in which dry toner is applied to the latent image of a latent image carrier, for example a photoconductor. A dry toner of this type leads to relatively thick toner layers, since the toner particles have a relatively large particle size and several toner particles have to be stacked on top of one another in order to ensure adequate color coverage. The dry toner layer applied to the latent image must be fixed, for which purpose a relatively high energy has to be used. This high energy leads to high stress on the final image carrier, preferably paper, as a result of the fixation by heat and / or pressure.

Liquid toners used to date contain a carrier liquid that is odorless and flammable. The final image carrier loaded with liquid toner is often also odorous. When using liquid toner, it is brought into contact with the latent image carrier. From US-A-5,943,535 it is known to use a water-based liquid toner which is brought into contact with a latent image carrier. Due to the conductive liquid toner, there is a precipitation on the latent image carrier corresponding to the electrostatic charge image.

From DE-A-30 00 019 a device for a liquid developer is known. A latent image, for example a potential pattern, is generated on a final image carrier. An applicator element carries a liquid layer. An air gap of a certain air gap width is set between the liquid layer and the final image carrier. Liquid elements from the liquid layer are transferred to the surface of the final image carrier due to the electrical potential.

From US-A-4, 982, 692 a method for printing is known which works with a liquid developer. Droplets of a liquid layer on an applicator element are transferred to the surface of a latent image carrier under the action of an electrostatic force field.

Furthermore, from US-A-5, 622, 805 a method with a liquid developer is known in which droplets on an applicator roller are transferred to the surface of a latent image carrier under the influence of an electrostatic field.

Reference should also be made to conventional printing processes, such as offset printing, which use liquid colorants. With these conventional printing processes, the printing form is not variable, so that economical printing of short runs is not possible. It is an object of the invention to provide a device and a method for cleaning and / or regenerating an image carrier which permits the use of a liquid colorant.

This object is achieved for a cleaning device by the features of claim 1. Advantageous developments of the invention are specified in the dependent claims.

The cleaning device according to the invention is preferably used in a printer or copier. Liquid dye is prepared in a coloring station in such a way that an amount of liquid in the form of a liquid layer is present per time and area on an applicator element. On this applicator element, preferably a belt or a roller, the liquid film is conveyed into the effective area of the potential pattern, the potential of which is distributed in accordance with an image pattern to be printed. The potential pattern preferably corresponds to an electrostatic charge image. The potential pattern was previously generated on the latent image carrier by suitable means, for example by electrostatically charging and exposing a photoconductor. An air gap exists between the surface of the liquid layer and the latent image carrier with the potential pattern. A potential contrast results between the surface of the applicator element and the image points of the potential pattern on the latent image carrier, for example supported by applying a voltage to the applicator element. Sections of the liquid layer are then partially detached from the applicator element and jump in small droplets or transfer by deformation of droplets according to the field lines the surface of the latent image carrier and color the latent image to the colorant image. This colorant image can then be transferred directly to the final image carrier, for example paper. Another possibility is that the colorant image is first transferred from the latent image carrier to an intermediate carrier and from there to the final image carrier.

A liquid colorant, preferably with a solids content of 20% or higher, is used in the invention. This liquid colorant contains a carrier liquid that is preferably odorless, non-flammable, environmentally friendly and non-toxic. Water is preferably used as the carrier liquid.

The use of a liquid colorant has the advantage that it can be easily stored in a storage container and that no segregation, no phase separation and no irreversible drying occur in this storage container and in the associated transport lines. The solids concentration or the colorant concentration can easily be changed by adding carrier liquid. The liquid colorant can be supplied in such a way that a colorant concentrate and the carrier liquid are stored and transported separately from one another.

Due to the injection of a defined excess charge into the droplets to be transferred when these droplets are detached from the applicator element, an unintentional background coloring is avoided.

Between the surface of the applicator element and the

There is an air gap on the surface of the latent image carrier, which is overcome by the liquid colorant. This coloring of the potential pattern on the latent image carrier over an air gap has the advantage that there is no wear on the latent image carrier or a closure is at least minimized. When the air gap is overcome, the droplets are focused according to the potential pattern, which results in a sharp line formation. The liquid colorant image aligns itself automatically according to the potential pattern, which in particular enables a clear definition of the image edges.

The use of a liquid colorant has the further advantage that relatively thin layers of color can be produced on the final image carrier. In this way, the colorant consumption is low and high printing speeds can be achieved. There are also advantages with regard to the fixation of the colorant image on the final image carrier. The energy to be used can be reduced and the processing speed increased.

The potential pattern on the latent image carrier is preferably designed as an electrostatic charge image. However, it is also possible to generate a potential pattern in the form of magnetic field lines. In this case, the liquid colorant should contain magnetically influenceable carrier particles which cause colorants to be transferred to the latent image carrier while overcoming the air gap and to color the latent image. The term “electrographic printing or copying *” means that a large number of electrically working methods can be used with which a latent image can be generated on a latent image carrier.

According to a further aspect of the invention, a method for cleaning an image carrier, in particular for electrographic printing or copying, is specified. According to another aspect of the invention, a device and a method for regenerating an image carrier are specified.

Conventionally, the surface of the latent image carrier is regenerated, e.g. of a photoconductor, by erasure exposure and by the effects of the electric field of a discharge corotron. There is no regeneration with respect to the surface energy. According to the aspect of the invention mentioned, the regeneration station according to the invention enables the surface of the latent image carrier to be regenerated with respect to maintaining a defined surface energy.

With the help of the aforementioned cleaning station according to the invention and the regeneration station according to the invention, it is possible to carry out continuous cleaning in connection with the regeneration of the surface energy conditions of a surface carrying a liquid colorant. In addition, the charge carrier injection ratios of the surface of the latent image carrier are regenerated. The continuous cleaning in connection with the regeneration extends the lifespan of the image carrier, ie a latent image carrier or an intermediate carrier. The regeneration of the latent image carrier and egg. Nes possibly downstream intermediate carrier can be coordinated with one another in such a way that constant adhesion conditions prevail at the contact point. In this way the transfer of the colorant image is improved. Furthermore, with the cleaning of the latent image carrier or the intermediate carrier, colorant can be recovered and used again for further printing processes. Embodiments of the invention are explained below with reference to the drawing. It shows:

Figure 1 shows schematically the structure of a pressure device, the liquid

Colorant works,

FIG. 2 shows a coloring station with an applicator roller for providing a thin layer of liquid,

Figure 3 shows the principle of transferring

Droplets from the liquid layer on the applicator element onto the surface of the latent image carrier,

FIG. 4 shows an example of the structure of the surface of the applicator element, a droplet carpet being formed on the surface,

Figure 5 shows the alignment of the liquid colorant on the surface of the

Latent image carrier corresponding to a charge image,

FIG. 6 shows an alternative embodiment for a coloring station,

FIG. 7 shows the surface of an applicator roller with continuous properties and the formation of a uniform liquid layer, FIG. 8 shows a cover layer of an applicator roller with first areas of increased electrical conductivity,

FIG. 9 shows a cover layer of an applicator roller with second areas of changed surface energy,

FIG. 10 shows a cover layer of an applicator roller with third areas of microscopic elevations,

FIG. 11 stochastically distributed microscopic elevations,

FIG. 12 shows a cover layer with a combination of first areas and second areas,

FIG. 13 a combination of first .. areas and third areas,

FIG. 14 shows a cover layer of an applicator roller, on which second areas and third areas are combined with one another,

FIG. 15 a cover layer in which first areas, second areas and third areas are combined with one another, FIG. 16 shows an overview of possible surface structures and their combinations,

FIG. 17 shows the surface structure of an applicator roller with a regular well structure,

FIG. 18 shows an applicator roller surface with a well structure and raised islands,

FIG. 19 shows a surface structure with a stochastic distribution of cells and with exposed ones

Peaks of microscopic elevations,

FIG. 20 shows an exemplary embodiment of a cleaning station,

Figures 21 to 26 different photo dielectric

Image creation processes for creating a latent image.

FIG. 1 shows, as an exemplary embodiment of the invention, a printing device which prints an end image carrier 10, for example paper. The final image carrier 10 is moved in the direction of the arrow P1. The printing device comprises a photoconductor drum 12 which rotates in the direction of arrow P2. A colorant image applied to the photoconductor drum 12 is transferred to an intermediate carrier drum 14 which is in contact with the photoconductor drum 12. The intermediate carrier drum 14 rotates in the direction of the arrow P3 and transfers the colorant image below is supported by a reloading corotron 16 on the lower side of the final image carrier 10.

On the circumference of the photoconductor drum 12 is an exposure station 18, a corotron 20, a light source 22 for generating a latent image on the photoconductor drum 12, an inking station 24 with an applicator 26, a hot air generator 28, a and Cleaning ^'ation 30 and a regeneration station 32 arranged. The functions of these units 18 to 32 are explained in more detail below.

A further cleaning station 34 and a hot air station 35 are arranged on the circumference of the intermediate carrier drum 14. The further cleaning station 34 can be constructed in the same way as the cleaning station 30.

FIG. 2 shows an exemplary embodiment of the inking station 24 with the applicator roller 26, which faces the outer surface of the photoconductor drum 12. The applicator roller 26 is supplied with a uniform liquid film 38 via a supply roller 36 ^'. In turn, this feed roller 36 is fed a constant amount of colorant over a scoop roller 40, which has a structure with cups 42 on its outer circumference. The scoop roller 40 dips a section into a scoop 44, in which a supply of colorant is contained.

A doctor blade 46 acts on the outer circumference of the scoop roller 40, which causes only the volume of colorant contained in the cups 42 to be conveyed. The feed roller 36 is deformable. The wells 42 empty on their surface, so that the smooth liquid film 38 forms on the surface of the feed roller 36. This liquid film 38 is brought up to the applicator roller 26. The feed roller 36 can rotate in the same direction or in the opposite direction to the applicator roller 26. Applicator roller 26 and feed roller 36 preferably move in synchronism, as shown in FIG. 2 by the direction arrows. The applicator roller 26 separates a smooth droplet carpet 48 from the smooth liquid film 38, the droplets of which jump under the action of an electric field from the surface of the applicator roller 26 in accordance with the image pattern onto the photoconductor 12, as can be seen, for example, with the droplet 50 in FIG. 2 is shown. The droplet 50 overcomes one

Air gap L, which is in the range from 50 to 1000 μm, preferably in the range from 100 to 200 μm. The surface of the photoconductor 12 can move in the same direction or in the opposite direction to the surface of the applicator roller 26. The surface speed of these two elements can be the same size or different. The surfaces of the photoconductor 12 and the applicator roller 26 preferably move at the same speed in the same direction, as shown in FIG. 2. The remnants of the droplet carpet 48 are removed from the surface of the applicator roller 26 by means of a doctor blade 52 and fed back to the colorant in the scoop pan 44 via a line system 54, 56. Another squeegee 58 removes the liquid film 38 on the feed roller 36 and supplies the residues to the colorant in the tub 44 via the element 56.

To support the transfer of the droplets 50 from the surface of the applicator roller 26 to the surface of the photoconductor 12, the applicator roller 26 is charged with a bi-potential ÜB in the form of a DC voltage. Because of this bias potential ÜB, there is a potential contrast between image points on the photoconductor 12 and the bias potential ÜB. The bias potential ÜB can additionally lent an alternating voltage with a frequency of preferably 5 kHz or higher.

The potential pattern on the photoconductor 12 is labeled UP. This' potential pattern UP is generated as a charge image, for example using a conventional electrographic process by charging with a corotron 20 (see FIG. 1) and by partial discharge using a light source 22, for example an LED print head or a laser print head.

At the image points of the surface of the photoconductor 12 defined by the potential pattern UP, a charge shift occurs within the liquid drops in the droplet carpet 48 due to the potential difference and, as a result, drops, for example the drop 50, are detached Drops injected. Due to the effect of the electric field and the kinetic impulse, the droplet 50 moves to the photoconductor surface and is focused by the field lines on ^'to be developed image areas.

Alternative embodiments for an inking station can have an anilox roller with a chambered doctor blade as the scoop roller. Another alternative provides that a smooth film of liquid is sprayed onto the feed roller. A further alternative embodiment provides that the applicator roller is immersed with a section in a bath with the colorant, and that the amount of liquid absorbed is metered via an elastic roller doctor, which acts on the surface of the applicator roller. Further alternative embodiments of the coloring station are explained further below. FIG. 3 shows further details in the area of the air gap L between the surface of the photoconductor drum 12 and the surface of the applicator roller 26. In this example, the surface of the applicator roller 26 has a regular structure with elevations 60 with a height of approximately 5 to 10 μm and a distance of about 10 to 15 µm from each other. These elevations 60 have a higher surface energy and a lower specific resistance than the surface sections 62 surrounding them. The surface energy of the elevations 60 is preferably in the range of 40 mN / m, the specific resistance is preferably in the range of 10 ¹ to 10 ⁶ Ωcm. The surface sections 62 have a surface energy preferably in the range less than 20 mN / m and a specific resistance of preferably greater than 10 ⁷ Ωcm. The droplets of the droplet carpet 48 shown in FIG. 3 form on the elevations 60. After the droplets have been transferred to the surface of the photoconductor 12 as a result of electrical field forces of the potential pattern UP, the droplets, for example the droplets 62, accumulate over the path x corresponding to the potential UP, as is shown in detail in section 64.

FIG. 4 shows an example of a section of the surface of the applicator roller 26 with the elevations 60 and the surface sections 62. The droplets 66 form on the

Surveys 60. These droplets have a size of approximately 0.3 to 50 μm in diameter. The droplets 66 have relatively low adhesion and receive an increased excess electrical charge on the surface under the influence of an external electric field (not shown). Such an external electric field is generated, for example, by the image areas defined by the charge image and to be colored with colorant, which are located near the elevations 60, for example at a distance L according to FIG. 2. The detachment by the effect of a latent charge image is thus facilitated. The drop size can be varied by changing the structure size of the structure of the surface. The droplet size is equal to or less than the printing resolution, preferably the droplet diameter is about a quarter of the ^'smallest to druk- kenden pixel.

FIG. 5 shows the distribution of the drop or several drops transferred to the photoconductor in accordance with the charge image and the field strength E. In this example, the image element 70 to be colored with colorant is defined by the negative charges on the surface of the photoconductor 12. The colorant .68 transferred to this image point 70 in the form of a droplet or several droplets orients itself in accordance with the charge image, in particular image edges are sharply shaped. The surface energies of the photoconductor 12 and the liquid colorant 68 are coordinated in such a way that a contact angle of greater than approximately 40 ° results.

FIG. 6 shows a further variant of a dyeing station 24. In this case, the applicator roller 26a does not carry a droplet carpet due to the continuous, homogeneous surface properties, but rather a continuous colorant layer 72. The surface energy of the surface of this applicator roller 26a is typically in the range from 10 to 60 mN / m, preferably between 30 and 50 mN / m. The specific resistance of the surface is in the range from 10 ² to 10 ⁸ Ωcm, preferably between 10 ⁵ to 10 ⁷ Ωcm. A smooth liquid film with a thickness in the range from 5 to 50 μm, preferably 15 μm, is applied to the appliqué. katorwalze 26a generated. This liquid film 72 is brought into the effective range of the potential pattern ^' UP. The distinguished by the charge image-image areas occurs due it ^■ potential contrast to a Ladungsverschie- bung within the liquid layer, and as a result of forming and detachment of droplets, such as shown by the drop 50th When detaching, an excess charge is also injected into the drop 50, in a manner similar to that explained in FIG. Because of the field effect and the kinetic impulse, the drop 50 moves to the surface of the photoconductor 12 and is focused by the field lines on the image areas to be developed. The further structure of the coloring station 24a corresponds to the coloring station 24 shown in FIG. 2.

FIG. 7 shows a representation similar to FIG. 3, but using the smooth, homogeneous liquid film 72 from which droplets 50 are released in accordance with the distribution of the potential pattern UP. Here, too, several droplets collect on the image area 74 in order to color this image area. Because of the potential pattern UP (x) present in the abscissa direction x, the colorant is focused on the image areas 74 to be developed. Due to the interaction between the electric field strength, the surface tension and the micro-charge distribution on the colorant 62, the liquid colorant 62 straightens up the photoconductor 12 at the field strength edges, which results in an edge smoothing of the picture elements. The surface of the photoconductor 12 should have a surface energy that does not result in the complete spreading of the liquid colorant 62, i.e. The colorant does not run apart.

FIGS. 3 and 7 show that the droplets from the surface of the applicator roller 26 and 26a onto it Jump over the opposite surface of the photoconductor 12. Such jumping need not necessarily be present. A drop of the drop carpet 48 on the applicator roller 26 or a drop formed on the applicator roller 26a from the smooth liquid film 72 can be elongated due to the electrical field effect according to the potential pattern UP. This deformation of the drop may be such ^'that for a short time, a fluid channel between the surface of the photoconductor 12 and the surface of the applicator 26 or 26a. forms and the drop can be in contact both with the surface of the photoconductor and with the surface of the applicator roller 26 or 26a. Due to the existing surface forces the droplet then travels completely or partly over 26 whereby it comes from the surface of the applicator to 26a to the surface of the photoconductor, ^{^'a'} imagewise Einfärbung-.

In the following figures 8 to 19, the structure and technical ^{characteristics'} of the surface of the applicator roller 26 will be explained. In principle, regardless of its shape, the applicator element is characterized in that its surface has a structure with a large number of areas in which the detachment of drops from the liquid layer is facilitated. This liquid layer can be present as a homogeneous, uniform layer or as a droplet carpet, as has already been mentioned above.

The applicator roller 26 according to FIG. 8 has a cover layer 76 with reduced conductivity and a surface energy in the range of preferably 30 to 50 roN / m with a relatively low polar portion of the surface energy, preferably in the range of less than 10 mΝ / m. A plurality of first regions 78 are embedded in this cover layer 76, which have an increased electrical conductivity compared to the cover layer 76. The first regions 78 are produced, for example, by doping the cover layer 76 by means of metal atoms. The first regions 78 can be repeated at regular intervals or can be arranged at stochastically distributed intervals. The distances between the first regions are preferably

78 at a distance of 0.3 to 50 μm from each other.

In the areas 80 left free by the first areas 78, the surface energy is increased, so that there is a tendency to form droplets. The cover layer can, for example, be made of DLC (diamont like carbon). The doping of the first regions 78 can be selected such that there is an almost rectangular transition in the conductivity. Alternatively, a smooth, continuous transition can be selected. The type of transition and also the size of the first areas 78 and the left areas 80 define the size of the droplets. In this way, droplets can be generated that have a diameter of up to 10 μm and can easily be detached from the regions 80.

The. An advantage of the arrangement shown in FIG. 8 is that the structuring of the cover layer 76 can take place with areas 78 of different conductivity on an otherwise smooth surface. At the first areas 78 of increased conductivity, charge carriers can be injected into the colorant droplets, which support the detachment of the droplets or of drops from a closed liquid film under the influence of an external electric field. FIG. 9 shows a further variant of the structuring of the surface of the applicator roller 26. The same reference symbols denote the same elements, which is also retained for the following figures. In the embodiment according to FIG. 9, structuring takes place by changing the surface energy in sections. This change in surface energy takes place in a fixed grid and abruptly. In a variant, the transition between sections of different surface energy can be continuous and the grid can be stochastically distributed. Cups 84 are embedded in the cover layer 76 made of a first material, the grid-shaped distribution of which takes place with a resolution of preferably 1200 dpi. The cups 84 are filled with a second material. The cups 84 with the second material form second areas 86 in the surface of the cover layer 76 with exposed areas 80 therebetween. A droplet carpet with droplets 82 is formed on these exposed areas.

The combination of two materials allows a variety of variations. For example, ^'can be used as first material "ceramic, and as the second material Teflon provided. May further as a first material DLC material, F-DLC material can be provided as a second material Teflon (fluorine diamond-like carbon material) or Sicon material and. A further material combination results if the first material is a Ni layer or a layer of Ni alloy, preferably CrNi, and Teflon is provided as the second material, the Teflon material preferably being embedded in the form of balls in the Ni layer.

The advantages of the arrangement according to FIG. 9 are that the structuring can take place on an otherwise smooth surface. The change in the surface energy leads specifically to the promotion of drop formation. about the numerous variants of material combinations allow adaptation to different colorant systems. The combination of materials also makes it possible to reduce the adhesion of the droplets formed to the surface of the applicator roller.

FIG. 10 shows a further example of a structuring of the surface of the applicator ^roller 26 such that the formation and detachment of drops from the liquid layer is facilitated. The structure of the surface has a multiplicity of third areas 88, which are formed as microscopic elevations on the otherwise macroscopically smooth surface. These third areas 88 can form a regular or a stochastic structure. The local wavelength of this structure is preferably in the range from 0.3 to 50 μm. The material of the cover layer should be such that it forms the largest possible contact angle with the liquid colorant used, preferably a contact angle greater than 90 °. A discontinuous layer of liquid is thus formed, preferably in the form of drops at the liquid's interface with the surface of the applicator roller 26. The microscopic elevations form small peaks and edges that lead to the formation of electrical field peaks in the effective area of an electrical field. These field peaks serve as separation points for the transfer of drops.

FIG. 11 shows that the third areas 88 can be distributed stochastically. The height difference between the highest points of the microscopic elevations of the third regions 88 and the level of the macroscopically smooth surface is approximately 2 to 20 μm, preferably 5 to 10 μm, for the examples according to FIGS. 10 and 11. FIG. 12 shows an example in which first areas 78 and second areas 86 are combined with one another. Both areas 78, 86 are formed at the same locations. Alternatively, the transition between the combined first and second areas 78, 86 and the remaining areas 80 may be continuous and the areas may be stochastically distributed. The combination of materials can be such as has been explained in connection with FIG. 9.

FIG. 13 shows a surface structure as a combination of the examples according to FIGS. 8 and 10. First areas 78 with increased conductivity are combined with a change in the surface contour. The first areas 78 and the third areas 88 can be formed regularly and alternately. The local wavelength of the first areas 78 and the third areas 88 can, however, also differ from one another, the local wavelength of the third areas 88 being at most one fifth of the local wavelength of the first areas 78. Due to the combination of the first regions 78 and third regions 88, the droplet formation, the size of the droplets and the injection of charge carriers into these drops can be influenced.

FIG. 14 shows an exemplary embodiment in which the surface is structured in such a way that second regions 86 and third regions 88 are combined with one another. These second areas 86 and third areas 88 can be formed regularly and alternately. Alternatively, the local wavelengths of the second regions 86 and the third regions 88 can be different from one another, the local wavelength of the third regions 88 being at most one fifth of the local wavelength of the second regions 86. FIG. 15 shows a further exemplary embodiment in which first areas 78, second areas 86 and third areas 88 are combined. In this way, the wetting of the surface of the applicator roller 26 can be set in a targeted manner.

Figure 16 gives an overview of the possible surface structures and their combinations. The top illustration shows that the cover layer of the applicator roller has first areas 78 with changed conductivity. In the example according to FIG. 16, the liquid colorant is shown as a continuous layer 77.

The example below shows the second areas 86 with changed surface energy, which are cup-shaped. ^'The' example below shows the surface structure with the third regions of a microscopic regular surface contour. The example below shows a stochastically distributed surface contour with third areas 88. The further example below shows a surface structure with a combination of first areas 78 and second areas 86. The further example below shows a combination of first areas 78 of changed conductivity and third Areas 88 with a microscopic surface contour. The penultimate example shows the combination of second areas 86 and third areas 88. The last example shows a surface structure with a combination of first areas 78, second areas 86 and third areas 88.

FIGS. 17 to 19 show concrete surface structures for an applicator roller. According to FIG. 17, a cover layer 76 with reduced conductivity and a surface energy in the range of 30 to 50 mN / m with a polar proportion greater than or equal to 5 mN / m, for example ceramic. This cover layer 76 has a regular cell structure, for example with a resolution of 1200 dpi. The cups 84 are made of a material with a lower surface energy than ceramic and with a lower conductivity than ceramic, for example Teflon. Overall, there is a flat roller surface. The surface of the filled cells has an area share of 60 to 90%, preferably 70 to 80%, of the total surface. The liquid film 38 is split at the contact point between the feed roller 36 and the applicator roller 26 (see FIG. 2). At the applicator roller 26, only those areas of the surface which have an increased surface energy take on liquid. Since these areas with increased surface energy are separated from areas with lower surface energy, a uniform droplet carpet 48 is formed. The droplet size is determined by the fineness of the structure of hydrophobic and hydrophilic areas. With a resolution of 1200 ^' dpi, drops of approx. 10 to 15 μm in diameter are formed.

FIG. 18 shows a further example for the structuring of the applicator roller surface. A cover layer 76 with reduced conductivity, for example ceramic, with a thickness of 1 to 500 μm is applied to the metallic base body 90 with a surface energy in the range of preferably 30 to 50 mN / m with a polar proportion greater than zero. The base body 90 or optionally the cover layer 76 is structured by a regular cell structure with a resolution of at least 1200 dpi. The cups 84 are made of a material with a lower surface energy than ceramic and a lower conductivity. as a ceramic, eg Teflon. The cups 84 are not completely filled, so that a roller surface with raised islands 92 is formed. The surface of the filled cells has an area share of 60 to 90% of the total surface. On contact with the feed roller 36, droplets 82 form on the raised areas 92 to form a droplet carpet 48.

FIG. 19 shows a further exemplary embodiment for an applicator roller. On the conductive base body 90, preferably made of metal, with a surface energy in the range from 30 to 50 mN / m with a polar proportion greater than or equal to 5 mN / m, there is optionally an intermediate layer 76 with reduced conductivity and a surface energy in the same range, for example ceramic, applied with a thickness in the range of 1 to 500 microns. The surface of the roller base body 90 or ^, optionally, the intermediate layer 76 is structured by a stochastic distribution of cups 84 in a grid spacing of 0.3 μm to 50 μm, preferably in the range from 0.3 μm to 20 μm. A cover layer 94, for example made of Teflon, with a material of lower surface energy and lower conductivity than the underlying layer 76, 90 fills the depressions so that the tips 96 of the stochastic surface structure remain uncovered. The surface of the filled-in depressions has an area fraction of preferably 60 to 90% of the total surface. On the exposed tips 96, droplets 82 form into a droplet carpet 48 upon contact with the feed roller 36.

Further assemblies of the printing device shown in FIG. 1 are described below. After the latent image has been colored on the photoconductor drum 12, physical and / or chemical processes, by evaporation of the carrier liquid in the colorant, to a thickening of the colorant image. This effect is intensified by the hot air generator 28, to which the colored ink image is fed as a result of the rotational movement of the photoconductor drum 12. In the example shown in FIG. 1, the colorant image is first transferred from the surface of the photoconductor drum 12 to the surface of an intermediate carrier drum 14 which is in contact with the surface of the photoconductor drum 12. The transmission takes place by mechanical contact and is preferably supported by a transfer printing voltage which is applied to the intermediate carrier drum 14. When the colorant image is transferred, the layer thickness of this colorant image is evened out; there is a smoothing. The intermediate carrier drum 14 consists of an electrically highly conductive body, preferably of metal, and has a coating with a defined electrical resistance, preferably in the range from 10 ⁵ to 10 ¹³ Ωcm.

Alternatively, instead of ^' the intermediate carrier drum 14 ^', a band can be provided as the intermediate carrier, which has a defined electrical resistance, preferably in the range from 10 ⁵ to 10 ¹³ Ωcm, and which consists of an electrically highly conductive element, which preferably consists of a metal the colored image is brought up on the latent image carrier, for example the photoconductor drum 12. This band also preferably carries an electrical potential on the surface which supports the transfer of the liquid image from the latent image carrier to the intermediate carrier. The electrical potential of the surface of the intermediate carrier is by means of an auxiliary voltage which is connected directly to the intermediate carrier or to the highly electrically conductive element which connects the intermediate carrier surface to the colored image on the latent image. Carrier brings up, is created. This auxiliary voltage can contain DC voltage components and AC voltage components.

At the transfer point from the latent image carrier to the intermediate carrier, for example the intermediate carrier drum 14, the following relation results with regard to the adhesive forces: the cohesion of the colorant image is greater than the adhesion between the intermediate carrier and the colorant image; the adhesion between the intermediate carrier and the colorant image is in turn greater than the adhesion between the surface of the latent image carrier and the colorant image. Because of these adhesive force conditions, the colorant image is transferred from the latent image carrier to the intermediate carrier.

The viscosity of the transferred colorant image can be increased further on the intermediate carrier by suitable means, preferably by a dry hot air stream. This ensures that the cohesion of the colorant image is sufficiently high to ensure complete transfer to the final image carrier 10. This also ensures that in the operating mode “collection ^{mode λλ} , which is explained in more detail below, the last colorant ^image generated in each case has a lower cohesion than the previously collected colorant ^images . In this way, there is no retransfer of colorant to the surface of the photoconductor.

According to FIG. 1, a hot air station 36 is provided for generating a dry hot air stream which acts on the surface of the intermediate carrier drum 14. The surface of the intermediate carrier drum 14 is guided past this in the direction of rotation P3. A cleaning station 30 or a cleaning station 34 is arranged on the circumference of the photoconductor drum 12 or the intermediate carrier drum 14. These cleaning stations 30, 34 serve to remove the remnants of the colorant image still remaining after printing. The structure of the cleaning station 30 or 34 is explained in more detail below. Furthermore, a regeneration station 32 is arranged on the periphery of the photoconductor drum 12 after the cleaning station 30, which generates defined surface properties and charge injection conditions on the surface of the photoconductor drum 12.

Various operating modes can be provided for realizing multi-color printing on the final image carrier 10. In a first mode, different color image separations are in sequence on the latent image carrier, that is, the photoconductor drum ^'12 is generated and sequentially transmitted directly onto the final image 10th

In a second mode a plurality of color image separations on the photoconductor ^'12 are superimposed. The superimposed color image extracts are then transferred together to the final image carrier 10.

A third mode of operation provides that, in order to implement multi-color printing, several color image separations are successively generated on the latent image carrier and superimposed on the intermediate carrier. The superimposed color image extracts are jointly transferred from the intermediate carrier to the final image carrier 10.

In a fourth operating mode there is a printing unit with a latent image carrier and one for each color image separation

Applicator element provided, each producing a color separation. The different color separations are successively which is transferred directly to the final image carrier 10 or first transferred to an intermediate carrier, for example the intermediate carrier drum 14, and transferred from there to the final image carrier 10. This operating mode is also called single pass procedure.

A fifth operating mode is characterized in that a single latent image carrier is provided for realizing multi-color printing, to which several applicator elements are assigned, for example in the manner of the applicator roller 26. Each applicator element generates a color image extract, which is transferred to the final image carrier 10 directly or initially to an intermediate carrier and from there to the final image carrier 10. This operating mode is also called multi-pass procedure.

An exemplary embodiment of the single-pass method has up to five complete printing units, each with a character generator, a latent image carrier and at least one inking station, and has a common intermediate carrier. The multicolored image is created in a single pass. For this purpose, the individual partial color images are generated on the latent image carriers assigned to them at such a time interval that they meet in register with the same surface area of the intermediate carrier which is moved past the individual colored latent image carriers one after the other and takes over the partial color images in contact with them , The partial color images together form the mixed color image in the overlay on the intermediate carrier. The cohesion of the individual colorant images is set on the respective latent image carrier in such a way that the cohesion of the colorant image first transferred to the intermediate carrier is higher than the respectively subsequent colorant image. For example, this can be step dry state of the colorant images can be achieved.

FIG. 20 shows an exemplary embodiment for the cleaning station 30. This cleaning station 30 has the task that the residues 101 of the colorant image that remain after the transfer of the colorant image are removed from the surface of the photoconductor drum 12. In the example shown, a brush roller 102 is used for this purpose, the brush 103 of which is in contact with the surface of the photoconductor drum 12. The brush roller 102 rotates in the direction of the arrow P4, preferably in the opposite direction to the movement of the photoconductor drum 12 in the direction P3. The brush 103 is arranged in such a way that the theoretical outer diameter of the brush roller 102 dips into the surface of the photoconductor drum 12. This ensures the defined stress on the bristles and the compensation of manufacturing tolerances. The brush roller 102 removes residues 101 of the liquid colorant by mechanical displacement, supported by the adhesion between the colorant and the brush hair and optionally by an electrostatic support. The base body of the brush roller 102 is preferably made of metal, to which a voltage UR is applied in order to achieve the advantageous electrostatic detachment effect. This voltage UR is a DC voltage, which can be superimposed by an AC voltage. After contact with the photoconductor drum 12, the brush 103 passes through a bath 106 in a tub 100, which preferably contains carrier liquid of the colorant in order to dissolve the residues of colorant in this carrier liquid. Advantageously, in order to detach the colorant residues from the brush 103, the contact area between the brush and the carrier liquid is subjected to ultrasound energy from an ultrasound source 107. After leaving the bath 106, a brush engages in the brush 103. Sucking device 104, which sucks off the liquid residues still adhering to the brush 103. That in the tub

100 existing mixture of carrier liquid and residues of colorant can be processed and reused for the printing process.

The cleaning station 30 shown in FIG. 20 removes residues

101 from the photoconductor drum 12. An identical or similarly constructed cleaning station can also be used to clean the surface of an intermediate carrier, for example the intermediate carrier drum 14. In general, a cleaning station of this type can be used for removing color residues that adhere to a carrier, generally referred to as an image carrier, to which a liquid colorant image has been applied.

Numerous modifications of the cleaning station are possible. For example, the cleaning station can contain a detaching roller which is pressed onto the surface of the image carrier. A doctor blade, which is arranged after the contact point as seen in the direction of rotation of the detaching roller, serves to strip off the colorant taken up by the detaching roller. The detaching roller is preferably immersed in a bath with carrier liquid. After passing through the bath, a further doctor blade can be arranged on the circumference of the detaching roller in order to scrape off the liquid on the surface of the detaching roller. The surface energy of the surface of the detaching roller should be set in such a way that a higher adhesion is present between the colorant residue and the surface of the detaching roller than the cohesion within the colorant residue. The cohesion within the colorant residue should be greater than the adhesion between the colorant residue and the surface of the image carrier. Another embodiment of the cleaning station ^includes' a cleaning pad, which is pressed against the image carrier. The cleaning fleece is preferably moved at a considerably lower speed than the peripheral speed of the 5. image carrier. The cleaning fleece can be designed as an endless belt which, after contact with the surface of the image carrier, is passed through a bath filled with carrier liquid. The colorant is dissolved and removed from the cleaning fleece. The endless belt is applied with a doctor blade and preferably with ultrasound. After leaving the bath, excess carrier liquid is removed from the endless belt, preferably using a pair of squeeze rollers. 5 Alternatively, the cleaning fleece can be rolled up on a dispenser roll and is brought into contact with the surface of the image carrier using a roller and a saddle. The cleaning fleece is then wound onto a receiver roll. The cleaning fleece is gradually moved from the dispenser roll to the recipient roll. Between two steps ^' up to several "thousand sheets can be printed.

In a further alternative, the cleaning station ent-5 holds a squeegee which is pressed onto the image carrier. If the image carrier is in the form of a tape, a roller or a rod can be provided as a counter bearing for the squeegee. 0 In another embodiment, the cleaning station such a wave soldering device, which directs a jet of cleaning liquid to the surface of the image carrier ^'includes. The carrier liquid of the colorant is preferably used as the cleaning liquid. 5 Another variant of the cleaning station contains a roller bath device which uses a roller to bring cleaning fluid to the surface of the image carrier. This cleaning liquid, preferably the carrier liquid of the colorant, dissolves the colorant residues, which are removed with the rotation of the roller. A doctor then acts on the roller mentioned, wiping off the dissolved liquid colorant.

Another variant of the cleaning station contains an Airknife. This displaces the liquid colorant from the image carrier to be cleaned. The displaced colorant residues can be collected, processed and reused for the printing process.

A further exemplary embodiment of a cleaning station contains a suction device which sucks the liquid colorant residue off the surface of the image carrier. The extracted exhaust air can be filtered and the liquid colorant separated, which is preferably reused in the further printing process.

Optionally, viewed in the direction of movement of the image carrier, a detachment station can be arranged in front of the cleaning station 30 (not shown), which applies a cleaning liquid to the surface of the image carrier. A scoop roller can be provided for application; alternatively, a section of the image carrier can pass through a bath with cleaning liquid. It is advantageous if the carrier liquid of the colorant is used as the cleaning liquid. It is advantageous if the contact point between the cleaning liquid and the image carrier is subjected to ultrasound energy. According to FIG. 1, a regeneration station 32 is arranged after the cleaning station 30 in the exemplary embodiment shown in the direction of rotation of the photoconductor drum 12. While the cleaning station 30 a. Ensures continuous mechanical cleaning, the regeneration station 32 serves to set and permanently guarantee defined process conditions, in particular with regard to the surface properties, such as the surface energy of the latent image carrier, the surface energy ratio between the surface of the latent image carrier, the liquid colorant and, if appropriate the surface of the intermediate carrier, and the surface roughness, ie the microscopic structure of the surface. Furthermore, the regeneration station serves to set defined process conditions with regard to the electrical properties on the surface of the latent image carrier, for example with regard to the charge injection conditions and the surface resistance. Accordingly, the regeneration station defines the surface energy that controls the wettability of the surface with the liquid colorant. For this purpose, the regeneration station applies to the surface of the image carrier, which can be an intermediate carrier or a latent image carrier, a substance which influences the surface energy, preferably surfactant solutions, in particular non-ionic surfactants dissolved in water. This substance can be applied, for example, with a layer thickness of less than 0.3 μm, which completely wets the surface, preferably in a time of less than 5 ms.

Furthermore, the regeneration station can contain a corona device which has a corona with an alternating voltage in the range from 1 to 20 kVss (measured from peak to peak) at a frequency in the range from 1 to 10 kHz Has. This corona device can alternatively be used to apply the substance or in combination with the substance.

In another alternative, cleaning and regeneration are combined in a single operation. For example, wave pool cleaning or roller pool cleaning is used. For this purpose, a substance, preferably a surfactant solution, is added to the cleaning liquid to control the surface energy. This substance is then transferred to the image carrier with the cleaning liquid. Excess cleaning liquid can be removed again, and such residues can be recycled.

Optionally, when cleaning with a cleaning liquid and an admixed substance which controls the surface energy and after regeneration has taken place, the surface of the image carrier can be dried by suitable means, for example by means of a warm and dry air flow which is directed onto the surface. This drying process serves to increase the surface-active content and thereby increase its effectiveness, as well as avoiding the disruptive effects of excess cleaning fluid.

In the following, photo-dielectric imaging processes are explained, with the help of which latent images can be generated on a photoconductor, which can be colored by the liquid colorant while overcoming the air gap. For this purpose, an image-wise distributed electric field is generated with the help of the layer system of the photoconductor, the components of which exert a force effect on charged particles, polarizable and conductive objects in the space above the surface, ie for example on polarizable ones Components of the colorant liquid. The electrical field distribution on the surface of the photoconductor is made visible during development using the transferring liquid colorant. The cleaning of the top layer of the ^' photoconductor, which comes into contact with ^' the colorant, must be adapted to the peculiarities of the liquid colorant. In addition to a cleaning of this surface and the production of a defined La ^'dung state of the upper insulating cover layer of the photoconductor must also be of the surface energy condition of this top layer after each Farbstoffübertragungswechsei restored or maintained. The material of the upper insulating cover layer of the photoconductor must accordingly be matched to the use of aqueous colorants. To color the surface of the photoconductor, the surface energy conditions must be such that the carrier liquid with the colorant adheres to the surface in the latent image areas to be colored. At least this liability condition must apply to the solids content of the colorant. In the areas of the surface of the photoconductor which are not to be colored, the electrical repulsion effect must predominate in such a way that no liquid comes into contact with the insulating surface of the photoconductor.

A variant is that because of the stability of the electric field over the insulating cover layer of the photoconductor, a permanent approach of the liquid containing colorant to this insulating layer can be carried out, the polarity of the solid colorant particles in the liquid must be such that it Particles are attracted by the electric field in the areas to be colored. The electrical field direction is in the areas not to be colored vice versa so that the charged solid colorant particles are repelled.

An imagewise coloring of the cover layer of the photoconductor can also be achieved in that the areas to be colored are relatively good due to the combined effect of the surface energy relationship between the insulating cover layer and the liquid and the electric field and the areas not to be colored because of the reversed field direction relatively poorly wetted. This type of coloring or the combination with the deposition of the charged solid colorant particles is particularly suitable for the development process at high speed. In order to implement a high-speed process with a pure particle deposition without significant wetting differences between the areas to be colored and those not to be colored, the liquid layer must be very thin and the concentration of the solid colorant particles must be relatively high. The largest possible particle charge is advantageous for high-speed development.

In the case of a conventional photoconductor with an external photoconductive layer, this photoconductive layer can be provided with a thin insulating cover layer according to one exemplary embodiment. This top layer is chosen so that it meets the requirements for wettability and other surface properties, e.g. fulfills the charge injection property for taking up and releasing a liquid colorant.

FIGS. 21 to 26 explain photo-dielectric imaging processes. A photo-dielectric process (FIGS. 21 and 22) can be used to generate the latent image, in which the formation of the latent image by an electric field in the photoconductor is controlled. A charge current controlled process can also be used for latent image generation (FIGS. 23 to 26).

An image generation process, which is also referred to as Nakamura process 1, is explained with reference to FIG. The photoconductors shown in the following figures each have a lower conductive layer 110, a middle photosensitive layer 112 and an upper insulating cover layer 114. This cover layer 114 determines the surface energy state, the electrical surface resistance and the charge injection properties of the photoconductor. The cover layer 114 itself does not significantly influence the electrophotographic process for generating the latent image.

In the image generation process according to FIG. 21, the layer system of the photoconductor is initially uniformly charged with one polarity, with charge carrier injections from the lower, conductive layer 110 into the photoconductor layer 112 and / or simultaneous exposure (not shown) to the formation of a electrical field in the photoconductor layer 112 is prevented. The layer system is then recharged with the opposite polarity, an electrical field being created in the photoconductor layer 112 (second step). In a third step, the layer system is exposed imagewise, whereby the latent image is created. Typical potential relationships are entered in FIG.

FIG. 22 relates to a photo-dielectric imaging process, which is also referred to as a Hall process. In a first step, the layer system of the photoconductor is first uniformly charged with one polarity, whereby an electrical field builds up both in the photoconductor layer 112 and in the cover layer 114. The layer system is then exposed imagewise (second step). As a result, the electrical field in the photoconductor layer 112 is reduced in exposed areas, while it is retained in unexposed areas. In a third step, the charge is recharged evenly with the same polarity as in the first step. A uniform surface exposure then takes place, the electrical field being reduced in all areas of the photoconductor layer 112 and the latent image being produced (fourth step). Typical potential relationships are again shown in FIG.

Figure 23 shows a fotodieelektrischen image forming process, which is also referred to as Katsuragawa process, ^'wherein the latent image forming a charging current process is used. In a first step, the layer system of the photoconductor is first uniformly charged with a polarity, wherein the creation of an electric field in the photoconductor layer 112 by charge carrier injection from the lower conductive layer 110 into the photoconductor layer 112 and / or by simultaneous uniform exposure (not shown) is prevented. In a second step, the layer system is exposed imagewise and, at the same time, is recharged with the opposite polarity for charging in the first step, an electrical field in the photoconductor layer 112 being prevented in exposed areas. In unexposed areas, an electrical field is created in the photoconductor layer 112. In a third step, the layer system is exposed uniformly, the latent image being produced. Typical potential relationships are also entered in FIG. Another charge current controlled imaging process is described in FIG. 24, referred to as the Canon NP process. In a first step, the layer system of the photoconductor. initially “uniformly charged” with a polarity, the generation of an electric field in the photoconductor layer 112 being prevented by charge carrier injection from the lower, conductive layer 110 into the photoconductor layer 112 and / or by simultaneous uniform exposure (not shown). The layer system is then exposed imagewise and discharged at the same time, preferably with the aid of an AC corona, the occurrence of an electric field in the photoconductor layer 112 being prevented in exposed areas. In unexposed areas, an electric field is created in the photoconductor layer 112 (second step). In a third step, the layer system is exposed evenly, creating the latent image. Typical potential relationships are again shown in FIG.

Figure 25 describes a charge current controlled ^' imaging process which is referred to as the Nakamura process 3. In a first step, the layer system is charged evenly with one polarity (the positive polarity was selected in the example according to FIG. 25) and at the same time exposed image-wise. In exposed areas, the formation of an electric field in photoconductor layer 112 is prevented, while in unexposed areas, a somewhat smaller electric field arises both in photoconductor layer 112 and in cover layer 114. Then, in the second step, there is a uniform charge with opposite polarity to the charge in the first step. The surface potential is then the same in the areas exposed and unexposed in the first step, in the example according to FIG. 25 approximately -500 Volt. The latent image is created during the final uniform exposure of the entire layer system (third step). Typical potential relationships are again shown in FIG. 25.

Figure 26 shows a charge current controlled imaging process called the Si ac process. In the first step, the layer system is charged evenly with one polarity (positive in the example according to FIG. 26) and at the same time exposed imagewise. In exposed areas, the formation of an electric field in photoconductor layer 112 is prevented, while in unexposed areas, a somewhat smaller electric field is created both in photoconductor layer 112 and in cover layer 114. In the subsequent uniform exposure of the entire layer system, the latent image is formed in the second step, the electric field disappearing in all areas of the photoconductor layer. Typical potential relationships are also entered in FIG.

Reference character list

10 final image carriers

12 photoconductor drum

Pl, P2,

P3 direction arrows

14 intermediate carrier drum

16 reloading corotron

18 Exposure station

20 corotron

22 light source

24.24a coloring station

26.26a applicator roller

28 hot air generator

30 cleaning station

32 regeneration station

34 additional cleaning stations

35 hot air station

36 feed roller

38 even liquid film

40 scoop roller

42 cells

44 ladle

46 squeegees

48 droplet carpet

50 droplets

52 squeegees

54.56 pipe system

ÜB bias potential

UP potential pattern

60 surveys

62 surface sections

64 detail

66 droplets

68 colorants 70 picture element

72 continuous layer of colorant

E field strength

74 Image location 76 Top layer

78 first areas of increased electrical conductivity

80 areas left blank

84 cells 86 second areas of changed surface energy

88 third areas of microscopic surveys

90 metallic body

92 sublime islands

94 top layer 100 tub

101 residues of colorant

102 brush roller

103 brush

P4 UR voltage arrow

104 suction device

106 bath

107 ultrasound source 110 conductive layer 112 photosensitive layer

114 top layer

Claims

Expectations

1. Device for cleaning an image carrier from color image residues, in particular for cleaning a latent image carrier or an intermediate carrier of an electrographic printer or copier,

in which a latent image carrier (12) is provided with ^" a potential pattern (UP) corresponding to an image pattern to be printed,

an applicator element (26, 26a) is provided with a layer (48, 72) of a colorant,

an air gap (L) is provided between the liquid layer (48, 72) and the surface of the latent image carrier (12) opposite it,

and in which, for coloring the latent image on the latent image carrier (12), droplets (50) are transferred from the liquid layer (48, 72) to the surface of the latent image carrier (12) while overcoming the air gap (L),

wherein the cleaning device is arranged on the periphery of the image carrier, and the residues of the colorant remaining after the transfer of the image colored with a liquid colorant are removed from the surface of the image carrier (12, 14).

2. Device according to claim 1, wherein the cleaning device (30) contains a brush roller (102) whose brush (103) is in contact with the surface of the image carrier (12) and removes the colorant.

3. Device according to one of claims 1 or 2, wherein the brush (103) after contact with the image carrier (12, 14) passes through a bath (106) which contains carrier liquid of the colorant to the remains of colorant in the carrier liquid to solve.

4. Device according to one of claims 1 to 3, wherein ultrasound energy (107) is applied to the contact area between the brush and carrier liquid to detach the colorant residues from the brush (103).

5. Device according to one of the preceding claims, wherein the on the brush (103) after leaving the bath

(106) liquid residues still adhering to the carrier liquid are sucked off by a suction device (104).

6. Device according to one of the preceding claims, wherein the colorant residues dissolved in the carrier liquid are used again for the printing process.

7. Device according to one of the preceding claims, wherein it contains a detaching roller which is pressed onto the surface of the image carrier, and that seen in the direction of rotation of the detaching roller after the contact point, a doctor blade for stripping off the farm means taken up by the detaching roller is arranged.

8. The device according to claim 7, wherein the detaching roller is immersed in a bath with carrier liquid, and that after passing through the bath a further doctor blade is arranged on the circumference of the detaching roller.

9. Device according to one of the preceding claims, wherein the surface energy of the surface of the release roller is chosen such that between the colorant residue and the surface of the release roller has a higher adhesion than the cohesion within the colorant residue, and that the cohesion within the colorant residue is greater than the adhesion between the colorant residue and the surface of the image carrier.

10. Device according to one of the preceding claims, wherein the cleaning station contains a cleaning fleece which is pressed onto the image carrier.

11. The device according to claim 10, wherein the cleaning fleece is moved at a significantly lower speed than the peripheral speed of the image carrier.

12. Device according to one of claims 10 or 11, wherein the nonwoven is rolled up on a dispenser roll, brought into contact with the surface of the image carrier by means of a roller or a saddle, and then wound up on a receiver roll.

13. The device according to claim 12, wherein the fleece is gradually moved from the donor roll to the recipient roll.

14. Device according to one of claims 10 or 11, wherein the fleece is designed as an endless belt that it after

Contact with the surface of the image carrier is passed through a bath filled with carrier liquid, and that the absorbed colorant is dissolved and removed.

15. The device according to claim 14, wherein the endless belt is applied with a doctor blade and preferably with ultrasound, and that after leaving the bath excess carrier liquid is removed from the endless belt, preferably using a pair of nip rollers.

16. Device according to one of the preceding claims, wherein the cleaning station contains a squeegee which is pressed onto the image carrier.

17. Device according to one of the preceding claims, wherein a roller or a rod is provided in an image carrier in the form of a tape as a counter bearing for the squeegee.

18. Device according to one of the preceding claims, wherein the cleaning station contains a wave bath device which directs a jet with cleaning liquid onto the surface of the image carrier.

19. Device according to one of the preceding claims, wherein the carrier liquid of the colorant is used as the cleaning liquid.

20. Device according to one of the preceding claims, wherein the cleaning station contains a roller bath device which brings cleaning liquid to the surface of the image carrier by means of a roller, which dissolves the colorant residue and is transported away with the rotation of the roller.

21. Device according to claim 20, wherein the roller is acted on by a doctor blade which strips off the dissolved liquid colorant.

22. Device according to one of the preceding claims, wherein the cleaning station contains an air knife, which strips off the colorant residue.

23. Device according to one of the preceding claims, wherein the cleaning station entails a suction device. holds, which sucks the liquid colorant residue from the surface of the image carrier.

24. The device according to claim 23, wherein the extracted exhaust air is filtered and the liquid colorant is separated, which is preferably reused in the further printing process.

25. Device according to one of the preceding claims, wherein seen in the direction of movement of the image carrier before

A cleaning station is arranged, which applies a cleaning liquid to the surface of the image carrier.

26. The device according to claim 25, wherein a scoop roller is provided for application, or that a portion of the image carrier passes through a bath with cleaning liquid.

27. Device according to one of the preceding claims, wherein the cleaning liquid is used as the cleaning liquid.

28. Device according to one of the preceding claims, wherein the contact point between cleaning liquid and image carrier is acted upon by ultrasonic energy.

29. Device for regenerating the surface of an image carrier, in particular for regenerating a latent image carrier or an intermediate carrier of an electrographic printer or copier,

the device being arranged on the periphery of the image carrier (12, 14) and generating defined surface properties on the surface of the image carrier (12, 14) in such a way, that the surface absorbs and releases a liquid colorant.

30. The device of claim 29, wherein a defined surface energy, which controls the wettability of the surface with the liquid colorant, an electrical surface resistance and / or defined charge carrier-injection ratios are set.

31. The device according to claim 29 or 30, wherein the device designed as a regeneration station (32) applies a substance influencing the surface energy to the surface of the image carrier, preferably surfactant solutions, in particular nonionic surfactants dissolved in water.

32. Device according to claim 31, wherein the substance influencing the surface energy is applied with a layer thickness of <0.3 μm, which completely wets the surface.

33. Device according to one of claims 29 to 32, wherein the regeneration station (32) contains a corona device which has a corona with an alternating voltage in the range from 1 to 20 kVss at a frequency in the range from 1 to 10 kHz.

34. Device according to one of claims 29 to 33, wherein the cleaning liquid contains a substance influencing the surface energy, preferably a surfactant solution.

35. Device according to one of claims 29 to 34, wherein the image carrier after passing through the regeneration station is dried, preferably by a warm and dry air flow.

36. Device according to one of the preceding claims 29 to 35, wherein, in addition to the regeneration device, a cleaning device is arranged on the circumference of the image carrier and removes the residues of the colorant remaining after the transfer of the image colored with a liquid colorant from the surface of the image carrier (12, 14) removed.

37. Device according to claim 36, wherein the cleaning and the regeneration of the surface properties of the image carrier are carried out in a common step.

38. A device according to claim 36, wherein for cleaning and regeneration of the surface properties of the image carrier in a common step, a substance, preferably a liquid is used which accommodates the residual ink of the ^'surface of the image carrier, preferably dissolved, and contains substances, which generate the surface properties of the image carrier in a defined manner.

39. Device according to one of claims 36-38, wherein the cleaning device is designed according to the features of one of claims 1-28.

40. Process for cleaning an image carrier from color image residues, in particular for cleaning a latent image carrier or an intermediate carrier of an electrographic printer or copier, in which a latent image carrier (12) is provided with a potential pattern (UP) corresponding to an image pattern to be printed,

to color the latent image on the latent image carrier (12), droplets (50) are transferred from the liquid layer (48, 72) to the surface of the latent image carrier (12) while overcoming the air gap (L),

and in which a cleaning device is arranged on the periphery of the image carrier, which removes the residues of the colorant remaining after the transfer of the image colored with a liquid colorant from the surface of the image carrier (12, 14).

41. The method according to claim 40, wherein the cleaning device (30) contains a brush roller (102), the brush (103) of which is in contact with the surface of the image carrier (12) and removes the colorant.

42. The method of claim 41, wherein the brush (103) after contact with the image carrier (12, 14) passes through a bath (106) which contains carrier liquid of the colorant in order to dissolve the residues of colorant in the carrier liquid.

43. The method according to any one of claims 41 to 42, wherein the detachment of the colorant residues from the brush (103) Contact area between the brush and the carrier liquid is subjected to ultrasonic energy (107).

44. The method according to any one of claims 41 to 43, wherein the liquid residues still adhering to the brush (103) after leaving the bath (106) with carrier liquid are sucked off by a suction device (104).

45. The method according to any one of the preceding claims, wherein the colorant residues dissolved in the carrier liquid are reused for the printing process.

46. The method according to any one of claims 40 to 45, wherein the cleaning device contains a release roller, which is pressed against the surface of the image carrier, and that seen in the direction of rotation of the release roller after the contact point a doctor blade for stripping the ink taken up by the release roller.

47. The method of claim 46, wherein the detaching roller is immersed in a bath with carrier liquid, and that after passing through the bath a further doctor blade is arranged on the circumference of the detaching roller.

48. The method according to any one of claims 46 to 47, wherein the surface energy of the surface of the peel roller is selected such ^'that higher adhesion is present between the residual ink and the surface of the peeling roller than the cohesion within the residual ink, and that the cohesion within the Colorant residue is greater than the adhesion between the colorant residue and the surface of the image carrier.

49. The method according to any one of the preceding claims, wherein the cleaning station contains a cleaning fleece which is pressed onto the image carrier.

50. The method of claim 49, wherein the cleaning fleece is moved at a significantly lower speed than the peripheral speed of the image carrier.

51. Method for regenerating the surface of an image carrier, in particular for regenerating a latent image carrier or an intermediate carrier of an electrographic printer or copier,

whereby defined surface properties are generated on the surface of the image carrier (12, 14) by means of a regeneration device arranged on the periphery of the image carrier (12, 14) in such a way that the surface absorbs a liquid colorant and releases it again.

52. The method of claim 51, wherein an electrical surface resistance and / or defined charge carrier-injection ratios are set via a defined surface energy, which controls the wettability of the surface with the liquid colorant.

53. The method according to claim 51 or 52, wherein the device designed as a regeneration station (32) applies a substance which influences the surface energy, preferably surfactant solutions, in particular nonionic surfactants dissolved in water, to the surface of the image carrier.

54. The method of claim 53, wherein the substance influencing the surface energy with a layer thickness of <0.3 μm is applied, which completely wets the surface.

55. The method according to any one of claims 51 to 54, wherein the regeneration station (32) contains a corona device which has a corona with an alternating voltage in the range from 1 to 20 kVss at a frequency in the range from 1 to 10 kHz.

56. The method according to any one of claims 51 to 55, wherein the cleaning liquid contains a substance influencing the surface energy, preferably a surfactant solution.

57. The method according to any one of claims 51 to 56, wherein the image carrier is dried after passing through the regeneration station, preferably by a warm and dry air flow.

58. The method according to any one of the preceding claims 51 to 57, wherein a cleaning device that can be arranged in the region of the image carrier in addition to the regeneration device removes the residues of a colorant that remain after the transfer of the image colored with a liquid colorant. the surface of the image carrier (12, 14) removed.

59. The method according to claim 58, wherein the cleaning and the regeneration of the surface properties of the image carrier are carried out in a common step.

60. The method of claim 59, wherein for cleaning and regeneration of the surface properties of the image carrier in a common step a substance, preferred as a liquid is used which absorbs the colorant residues from the surface of the image carrier, preferably dissolves, and contains the substances which produce the surface properties of the image carrier in a defined manner.