EP1465023A1 - Corotron with counter electrode - Google Patents

Abstract

The printer or copier apparatus has two transfer belts (41,42) to transfer the toner images (44,45) on to both sides of the carrier (43) to be printed. A transfer corotron (47a) recharges the toner particles to reverse their polarity. The toner particles are transferred to the surfaces of the carrier (43) by an electrical field (F) at the transfer point. Both transfer belts (41,42) carry their toner particles towards the carrier (43) with the same polarity, either positive or negative. A discharge corotron (47a) is aligned at one belt (42) in front of the printing transfer point, to reverse the polarity of its carried toner particles. Two facing rollers (49a,49b) are at the transfer printing point, charged with DC to form the electrical field (F) at the transfer printing point to print the toner particles. One transfer roller (49a,49b) has a mass potential, and they have a symmetrical or asymmetrical potential against mass. The transfer belts (41,42) pass round the transfer rollers (49a,49b) by a defined angle. Two guides, as rollers or deflection stirrups, are in front of the transfer rollers (49a,49b) in the direction of carrier (43) travel, for the transfer belts (41,42) and the carrier (43) to pass between them. Two guides, with a mass potential, can flank the transfer belts and the carrier in front of the transfer printing point. The electrical field (F), to print the toner particles, is formed between one transfer roller (49b) and a diagonally opposed guide. The other transfer roller (49a) and the other guide have a floating potential. The transfer rollers have a metal core and an elastic core cladding of a material with a set electrical conductivity of 0.5 X 10 -6>to 5 X 10 12>ohm/cm, and preferably 0.5X10 5>to 5 X 10 9>hm/cm. The elastic core cladding has a Shore hardness of 10-90 Sh (A) and preferably 20-70 Sh(A). The core cladding has a thickness of 0.2-15.0 mm and preferably 0.5-2.0 mm. The elastic core cladding has an additional cladding of a plastics with a fluoro content, which is electrically insulated and in a max. thickness of 40 mu m and preferably 0.1-20.0 mu m. The core claddings contain conductive filling materials preferably of soot, a silicate and an oxide. The carrier material to be printed is a continuous length and preferably of paper, or separate paper sheets. Each transfer module at the printer/copier has a corotron system. An independent claim is also included for a corotron assembly with at least one corotron wire with one potential and at least one counter electrode with a second and different potential and at least one intermediate carrier between them. The counter electrode has electrically conductive projections, with their peaks towards the corotron wire, on a plane parallel to the corotron wire and the intermediate carrier. Preferred Features: The counter electrode projections are parallel to the longitudinal axis of the corotron wire, as separate pins or pointed projections. The counter electrode can be a blade, with its edge parallel to the longitudinal axis of the corotron wire. The blade edge is notched, with the tooth points aligned towards the corotron wire. The cross section of the counter electrode blade tapers towards the corotron wire. The counter electrode blade has a width of 0.02-0.5 mm and preferably 0.02-0.1 mm. The counter electrode can be a wire, parallel to the longitudinal axis of the corotron wire, where both are on a plane at right angles to the intermediate carrier. The intermediate carrier is a photo conductive belt or a transfer belt. The intermediate carrier path is at a gap from the counter electrode of 0.2-4.0 mm and preferably 0.2-1.0 mm. The intermediate carrier has a high electrical resistance of >=10 6>ohm/cm. The corotron system is a polarity change, charge, printing transfer or deletion corotron.

Description

The invention relates to a printer or copier with a Transfer station for simultaneous printing on both sides of a Support material. The invention further relates to a corotron device, which can be used in the transfer station mentioned is.

High performance printers and high performance copiers often own the ability to face the front and back of a Backing material, such as paper, to be printed. This Operating mode is also called duplex printing. It is known, first a page, for example the front, with a Print the toner image and then the carrier material to turn. It is then fed again to the same printing station, around the second side, usually the back, to print with a second toner image. This kind of duplex printing is both for ribbon-shaped carrier material as well as known for single sheet carrier material. At a such printing operation is due to the additional transportation and the turning of the carrier material does not affect the total throughput high. In another known solution, a printer or copying system two printing units, each printing unit one Printed side of the carrier material. In this case, inside the system considerable space for the two printing units needed and the technical effort is great.

In a printing device known from US-A-5,526,107 becomes continuous paper of a transfer location of a photoconductor cylinder fed, the electrophotographic on two surfaces Units for the generation of different colored toner images Has. The continuous paper is opened at the transfer location printed on the front with a first color, then the continuous paper is deflected and one opposite the transfer location Printing point fed to the same photoconductor cylinder and printed there with the back.

From EP-A-0 320 985 it is known to provide a transfer belt use which carries toner images from a photoconductor drum have been transferred to the transfer belt. The Toner images on the transfer belt are then at the transfer location transferred to the carrier material.

From DE-A-197 13 964, the same content as US-A-5,797,077 is a transfer station for simultaneous printing known on both sides of a carrier material (duplex printing). The transfer station contains a swiveling transfer printing station, in a first position a transfer belt from the carrier material stops so that no toner images on it Carrier material are transferred. Be in this position generated on the transfer belt overlaying toner images to enable multi-color printing. In a second position the transfer station is pivoted to the carrier material and transfers the multi-color toner image.

WO 87/02792 describes a corotron device with a corotron electrode described, the counter electrode as a metal plate is executed. This metal plate is at ground potential. That between the corotron electrode and the counter electrode generated electric field leads to an influence on the charge the toner particles.

It is an object of the invention to provide a printer or copier create a simultaneous printing from the front and back of a carrier material with little effort and with high print quality.

This object is solved by the features of claim 1. Advantageous further developments are in the dependent claims specified.

According to the invention there are two at the transfer location transfer belts opposite, the toner particles different Have polarity. It now becomes an electrostatic one Generates field that is directed so that the toner particles both from the first transmission band and from the second Transfer belt are repelled and affect the respective Attach the surfaces of the carrier material. In this way a simultaneous transfer printing is achieved. The route of transportation of the carrier material remains short because the carrier material is not at two printing stations or twice at one printing station must be passed. There is also no intermediate fixation the toner images transferred to the carrier material, which reduces the technical effort and the Print quality remains high.

In a preferred embodiment, both have transmission bands seen in the feed direction of the carrier material in a section in front of the transfer point, toner images with toner particles same polarity, before the transfer point A transfer corotron is arranged along one of the transfer belts is which creates an electric field that the Polarity of the toner particles on this transfer belt Reloading reverses. These measures can be used for both transmission bands a uniform toner system, for example a positive or negative toner system with positive or negative charge of the toner image can be used. Accordingly, is the print quality on both sides of the substrate almost identical.

Another embodiment is characterized in that that two transfer rollers face each other at the transfer location, and that to the transfer rollers a DC voltage is created, which is the electric field for transfer printing which creates toner particles. Ensure the transfer rollers on the one hand a precise guidance of the carrier material and the transfer belts in the area of the transfer printing point. on the other hand allow you to easily build a electrical field in the area of the transfer printing point.

In practice, an embodiment has proven itself in seen in the feed direction of the carrier material before Transfer rollers two guide elements are arranged between which the transfer tapes and the carrier material is led. In this way, the transfer belts and the carrier material along a relatively large distance led by mutual contact. At the transfer location the fogging effect is reduced because the toner particles only a little or no distance from the surface of the carrier material have and so a precise transfer printing takes place '.

According to a further aspect of the invention, a corotron device indicated with the features of claim 25. This corotron device can advantageously be used in conjunction use with the transfer modules mentioned.

For printing on a final image carrier, e.g. Paper, becomes a Transfer of a toner image on an intermediate carrier on the final image carrier mechanically, thermodynamically or made electrostatically. For an electrostatic Transfer the toner image from a photoconductor belt to one The toner particles must be on an intermediate carrier or on a final image carrier have a certain potential for tension. The electrostatic The toner particles are transferred by forces in the electric field and is based on a potential difference between the toner particles and the final image carrier on which the toner image is to be transferred. The power through that electrical field must be greater than the binding forces, through which the toner particles on the intermediate carrier for Toner images from which they are to be transferred are held.

In electrographic printing and / or copying facilities Dry toner particles for electrographic transfer with a suitable voltage potential, so that the Transfer the toner particles to a material without additional Charge influence of the toner particles in the printer or copier can be carried out. Should the final image carrier on both Pages are printed (duplex printing), the final image carrier must be turned, or there is a simultaneous or time-delayed transfer of the toner particles from both sides on the final image carrier. To transfer without intermediate fixation to realize the toner image transferred to the final image carrier, the toner particles on the first page of the Intermediate carrier to the toner particles of the second side Show potential difference. Preferably the toner particles from a positive potential to a negative potential Voltage potential, in relation to the ground potential, transhipped. Thus, the toner particles can be simultaneously or staggered in time without intermediate fixation of the intermediate carrier be transferred from both sides to the final image carrier. Pull the toner particles on both sides of the final image carrier different potentials through the final image carrier through and / or through the potential difference attracted to the final image carrier so that they on the Final image carriers stick.

After the transfer process, toner particles adhere to the intermediate carrier from which they are to be transferred, ie they have not been successfully transferred. These are toner particles of a few percent of the toner image, usually considerably less than 20 percent. These untransferred toner particles usually have a low or incorrect voltage potential. In order to carry out a further transfer of these untransferred toner particles, for example for cleaning the intermediate carrier, with high efficiency, it is necessary to charge the toner particles to a defined potential. This loading process takes place with a corotron device. The intermediate carrier forms the counter electrode to the corotron device. If the intermediate carrier is a conductive material with a specific resistance of less than 10 ⁶ ohm cm, the intermediate carrier is connected to ground potential or to another suitable voltage potential and thus serves as a counter electrode. If, for example in the case of a photoconductor, the intermediate carrier is provided with a light-sensitive cover layer whose dark resistance is very high-impedance (for example greater than 10 ⁶ ohm cm), a counter electrode must be arranged on the back of the intermediate carrier. Counter electrodes are preferably designed as metal plates or as conductive deflection rollers. Since deflection rollers are associated with a high mechanical outlay, increased space requirement and high costs, metal plates are primarily used as counter electrodes.

The counter electrode should have a low contact resistance own the intermediate carrier. The intermediate carrier is on the fixed counter electrode passed without contact. Around The intermediate carrier must achieve the low contact resistance at a short distance on the fixed counter electrode to be led past. This distance is preferably 0.2 mm to 1.0 mm. The forces between two bodies an electric field due to their potential difference generated are one with the forces between two plates Plate capacitor comparable, with a plate of the Plate capacitor through the counter electrode and the other Plate formed by the underside of the intermediate carrier becomes. A force in the direction then acts on the intermediate carrier the fixed counter electrode. This force leads to the fact that the band-shaped intermediate carrier on the counter electrode deflects in their direction, touches it and clings to it. Through the contact between the moving band-shaped Intermediate carrier and the fixed counter electrode is created Static and sliding friction. The in addition to the drive of the intermediate carrier due to this friction between the intermediate carrier and counterelectrode required mechanical energy must be from the Drive unit of the intermediate carrier are applied. Moreover becomes the intermediate carrier due to the sliding friction and / or the counter electrode is worn.

The task is therefore to specify a corotron device at between the intermediate support for toner images and the counter electrode low attraction forces occur and the charge carrier exchange is guaranteed.

According to the new corotron device, the counter electrode leading surveys, the endpoints of which are towards the Corotron wire protrude and in a plane parallel to Longitudinal axis of the corotron wire. Through this training the counter electrode is achieved that the attractive force between the intermediate carrier and the counter electrode considerably is reduced. This attraction depends crucially on the effective area. The relevant effective area is the surface of the counter electrode facing the intermediate carrier. By arranging electrically conductive elevations, the Endpoints are the relevant effective area ensures that the effective area and thus also the attractive forces between the intermediate carrier and the counter electrode are low. This arrangement also achieves that the curvatures on the elevations intensified it Exchange of carriers due to peak discharge comes.

A preferred embodiment provides that the surveys the counter electrode along the longitudinal axis of the corotron wire are arranged. This ensures that the electrical Field for influencing the charge of the toner particles evenly trained and the arrangement of the counter electrode to save space is possible.

Another embodiment is characterized in that the counter electrode contains individual pins as elevations. Thereby it is achieved that the counter electrode from standardized Components can be manufactured inexpensively.

Another preferred embodiment variant consists in that the counter electrode contains tapered bumps. This ensures that the effective area of the counter electrode and thus the attraction between the intermediate carrier for toner images and counterelectrode further reduced becomes.

According to a further aspect, a corotron device for an electrographic printing and / or copying device provided that the counter electrode in the manner of a blade with a cutting edge is formed, the cutting edge being parallel is arranged to the longitudinal axis of the corotron wire. With this Design is achieved that e.g. a sheet metal plate, which are arranged perpendicular to the intermediate carrier for toner images is and across the width of the intermediate carrier for toner images runs, is used as a counter electrode. Such an arrangement is space-saving and inexpensive. By this arrangement is also achieved by the curvatures the cutting edge for an independent exchange of load carriers (to a peak discharge).

Another cheap embodiment of the corotron device provides that the cutting edge of the counter electrode is serrated is and that the prongs are in the direction of the corotron wire taper so that the end points and / or end faces of the zakken protrude in the direction of the corotron wire and parallel to Longitudinal axis of the corotron wire. This ensures that the effective area from which the amount of attraction between the intermediate carrier for toner images and counter electrode is dependent on the continuous blade is reduced, which further reduces the attraction becomes. The peak discharge is further favored.

According to a further aspect, a corotron device for an electrographic printing and / or copying device provided that the counter electrode is formed by a wire is, whose longitudinal axis is parallel to the longitudinal axis of the Corotron wire is arranged. With this configuration achieves that e.g. also a corotron wire as a counter electrode is arranged. This wire runs across the width of the intermediate carrier. Such an arrangement is space-saving and reduced the number of components used.

Figur 1

eine schematische Schnittdarstellung eines elektrofotografischen Druckgeräts zum monochromen und/oder farbigen, ein- oder beidseitigen Bedrucken eines bandförmigen Trägermaterials, bei dem die Transferstation nach der Erfindung eingesetzt werden kann,

Figur 2

eine schematische Schnittdarstellung eines Druckgeräts nach Figur 1, welches das Trägermaterial beidseitig bedruckt,

Figur 3

schematisch eine Anordnung wesentlicher Teile der Transferstation mit Umladung der Tonerteilchen,

Figur 4

eine Detaildarstellung der Anordnung nach Figur 3 zur Erläuterung der Wirkungsweise,

Figur 5

ein elektrisches Ersatzschaltbild, das die Widerstandsverhältnisse und Stromverhältnisse an der Umdruckstelle wiedergibt,

Figur 6

eine Anordnung ähnlich der nach Figur 3 mit negativem Tonersystem,

Figur 7

schematisch die möglichen Potentialverhältnisse an den Umdruckwalzen,

Figur 8

ein Ausführungsbeispiel, bei dem die Übertragungsbänder die Übertragungswalzen teilweise umschlingen,

Figur 9

ein Ausführungsbeispiel mit Führungswalzen,

Figur 10

eine Detaildarstellung der Anordnung nach Figur 9,

Figur 11

eine Anordnung ähnlich der nach Figur 9, bei der das zum Umdrucken erforderliche elektrische Feld zwischen der Führungswalze und der Übertragungswalze aufgebaut wird,

Figur 12

ein elektrisches Ersatzschaltbild zum Ausführungsbeispiel nach Figur 11,

Figur 13

eine Anordnung nach Figur 11, wobei zusätzlich Zuführwalzen vorgesehen sind,

Figur 14

ein Ausführungsbeispiel mit Umlenkbügeln,

Figur 15

die Stromverhältnisse beim Ausführungsbeispiel nach Figur 14,

Figur 16

das Ausführungsbeispiel nach Figur 14 mit isolierten Umlenkbügeln,

Figur 17

ein Ausführungsbeispiel mit elektrisch leitenden Umlenkbügeln, die über einen Widerstand gegen Massepotential geführt sind,

Figur 18

ein Ausführungsbeispiel ähnlich dem nach Figur 13,

Figur 19

mehrere Ausführungsbeispiele für eine Übertragungswalze,

Figur 20

eine Übertragungswalze aus einem hochohmigen Material mit seitlichen Elektrodenanschlüssen,

Figur 21

eine Übertragungswalze mit einem elektrisch leitenden Kern und einer hochohmigen Beschichtung,

Figur 22

eine Umladekorotroneinrichtung mit zwei Korotrondrähten und mit zwei als Klingen ausgebildeten Gegenelektroden,

Figur 23

ein Umladekorotron mit einem Korotrondraht und einer als Gegenelektrode eingesetzten Klinge, wobei die Feldlinien des wirksamen elektrischen Feldes angedeutet sind,

Figur 24

die Darstellung einer Gegenelektrode, die als Klinge ausgeführt ist,

Figur 25

die Darstellung einer Klinge, wobei die Schneide gezackt ist,

Figur 26

die Darstellung einer Gegenelektrode, die aus einer Anordnung von Einzelstiften besteht,

Figur 27

die Darstellung einer Gegenelektrode, die aus einem Draht besteht, und

Figur 28

eine Umdruckkorotroneinrichtung mit einem Korotrondraht und mit einer als Klinge ausgebildeten Gegenelektrode.

Embodiments of the invention are explained below with reference to the drawings. It shows

Figure 1

2 shows a schematic sectional illustration of an electrophotographic printing device for monochrome and / or colored printing on one or both sides of a strip-shaped carrier material, in which the transfer station according to the invention can be used,

Figure 2

2 shows a schematic sectional illustration of a printing device according to FIG. 1, which prints the carrier material on both sides,

Figure 3

schematically an arrangement of essential parts of the transfer station with transfer of the toner particles,

Figure 4

3 shows a detailed representation of the arrangement according to FIG. 3 to explain the mode of operation,

Figure 5

an electrical equivalent circuit diagram that shows the resistance and current conditions at the transfer location,

Figure 6

an arrangement similar to that of Figure 3 with a negative toner system,

Figure 7

schematically the possible potential relationships on the transfer rollers,

Figure 8

an embodiment in which the transfer belts partially wrap around the transfer rollers,

Figure 9

an embodiment with guide rollers,

Figure 10

9 shows a detailed representation of the arrangement according to FIG. 9,

Figure 11

an arrangement similar to that according to FIG. 9, in which the electric field required for transfer printing is built up between the guide roller and the transfer roller,

Figure 12

an electrical equivalent circuit diagram to the embodiment of Figure 11,

Figure 13

11 shows an arrangement according to FIG. 11, feed rollers additionally being provided,

Figure 14

an embodiment with deflection brackets,

Figure 15

the current conditions in the embodiment of Figure 14,

Figure 16

the embodiment of Figure 14 with insulated deflection brackets,

Figure 17

an embodiment with electrically conductive deflection brackets, which are guided via a resistance to ground potential,

Figure 18

an embodiment similar to that of Figure 13,

Figure 19

several embodiments for a transfer roller,

Figure 20

a transfer roller made of a high-resistance material with side electrode connections,

Figure 21

a transfer roller with an electrically conductive core and a high-resistance coating,

Figure 22

a recharging corotron device with two corotron wires and with two counter electrodes designed as blades,

Figure 23

a recharging corotron with a corotron wire and a blade used as a counter electrode, the field lines of the effective electric field being indicated,

Figure 24

the representation of a counter electrode, which is designed as a blade,

Figure 25

the representation of a blade with the cutting edge serrated,

Figure 26

the representation of a counter electrode, which consists of an arrangement of individual pins,

Figure 27

the representation of a counter electrode, which consists of a wire, and

Figure 28

a transfer printing corotron device with a corotron wire and with a counter electrode designed as a blade.

FIG. 1 shows a printing device for monochrome and / or colored, printing on one or both sides of a ribbon-shaped carrier material, for example a paper web. The pressure device is of modular construction and has a feed module M1, a pressure module M2, a fixing module M3 and a post-processing module M4. The feed module M1 contains elements for feeding a continuous paper removed from a stacker to the printing module M2. This print module M2 contains the transfer station, which printed on the carrier material, which is then in the fixing module M3 fixed and cut in the post-processing module M4 and / or stacked.

The printing module M2 contains those for printing a ribbon-shaped Carrier material 10 required with toner images Units on both sides of a transport channel 11 for the Carrier material 10 are arranged. These aggregates include essentially two differently configurable electrophotography modules E1 and E2 with associated transfer modules T1 and T2, which together form the transfer station T. The modules E1 and T1 are assigned to the front of the carrier material 10, the modules E2 and T2 on the back of the carrier material 10th

The essentially identical electrophotography modules E1 and E2 contain a guided over deflection rollers 12 and preferably driven by an electric motor in the direction of the arrow seamless photoconductor tape 13, e.g. an organic Is photoconductor, also called OPC. Along the photosensitive The aggregates are outside of the photoconductor belt 13 arranged for the electrophotographic process. These aggregates serve 13 individual color separations on the photoconductor belt to generate assigned toner images. For this, the Photoconductor 13 moved in the direction of the arrow initially using a Charger 14 is charged to a voltage of approximately -600 V. and depending on the characters to be printed using a consisting of an LED comb character generator 15 to about - Discharge 50 V.

The latent thus produced, located on the photoconductor 13 Charge image is then 16/1 using developer stations up to 16/5 colored with toner. Then using the intermediate exposure device 17 the toner image is loosened and in an intermediate transfer area 18 on a transfer belt 19 of the transfer belt module T1 using a transfer corona device 20 transferred. Then the discharge corona device 21 the entire photoconductor band 13 over the unloaded entire width and via a cleaning device 22 cleaned from adhering toner dust with cleaning brushes. A subsequent intermediate exposure device 23 ensures appropriate charge conditioning of the photoconductor belt 13, which, as already described, evenly charged using the charger 14 becomes.

Using the electrophotography module E1 or E2 individual Color separations associated with toner images generated, their entirety forms the color image to be printed. For this are the Developer stations 16/1 to 16/5 switchable. she each contain the one assigned to a single color separation Toner. For example, the developer station contains 16/1 black toner, the developer station 16/2 color toner Yellow, the developer station 16/3 toner of magenta color, the Developer station 16/4 toner of the color cyan and for example the developer station 16/5 blue toner or toner one Spot color. Both single-component and as well as two-component toner developer stations be used. One-component toner developer stations are preferred used that work with fluidizing toner, such as this, for example, from US Patent 477106 (Applicant Fotland) are known. The subject of this U.S. patent is part of the present disclosure.

To achieve the switchability of the developer stations, i.e. to operate each individual developer station individually to be able to use these stations when using Fluidizing toner according to the German patent application DE 196 52 866 may be formed. Switching the developer station accordingly takes place by changing the electrical bias the transfer roller or by changing the electrical Preloading the applicator roller. It is also possible to switch the developer stations in that they mechanically shifted and thereby in contact with the photoconductor belt 13 are brought. Such a principle is e.g. known from DE-A-196 18 324.

When operating the printing device, the developer stations 16/1 to 16/5 by a single developer station creates a toner image that a single Color separation is assigned. This toner image is then over the transfer printing device 18 in connection with the transfer corona device 20 electrostatically on the transfer belt 19 transferred. The transfer module T1 contains this transfer band 19, which consists of a rubber-like substance, um several deflection devices guided and motor-driven is. The transfer belt 19 is similar to the photoconductor belt 13 preferably endless and without a seam. It is in The direction of the arrow moves, starting from the transfer area with the roller 18 and the transfer corona device 20 a transfer station 24 with transfer rollers, from there on around a deflecting roller 25 to a cleaning station 26 and from there in turn to the transfer area 18, 20 with the one arranged there Deflection roller 27.

The transfer belt 19 in the transfer module T1 serves as a collector for the individual toner images assigned to the color separations, via the transfer device 18, 20 onto the transfer belt 19 are transmitted. The individual toner images are arranged one above the other so that a color image corresponding Total toner image is created. To the total toner image to be able to generate and then to the front of the To transfer carrier material 10 contains the transfer module T1 a switchable transfer printing station 24. This can, accordingly 1, several mechanically displaceable Transfer rollers 28 contain an associated transfer corona device 29. Are in the "Collect" operating state the transfer rollers 28 and the transfer corona device 29 accordingly the direction of the arrow moved upwards so that the Transfer belt 19 is spaced from the carrier material 10. The individual toner images are in this state by the electrophotography module E1 taken over and on the transfer belt 19 overlaid. The cleaning station 26 is by pivoting disabled. The carrier material 10 is in this Operating state in the area of the transfer printing station 24 at rest.

The electrophotography module E2 and the transfer module T2 for the back of the record carrier 10 are corresponding the modules E1 and T1 constructed. Here too is on the transmission line a total toner image by collecting individual Generated toner images for the back, being in the operating state The corresponding transfer printing station 24 also "collects" here is pivoted away.

For simultaneous printing on the front and back of the Carrier material 10, the transfer tapes 19 of the Transfer modules T1 and T2 in the area of their transfer printing stations 24 brought into contact with the carrier material 10 at the same time while moving the carrier material 10. At the same time they are Cleaning stations 26 of the transfer modules T1 and T2 pivoted and activated. After transferring the two toner images on the front or the back of the carrier material 10 toner image residues adhering to the transfer belts 19 from the cleaning stations 26. After that closes there is another collection cycle for generating new toner images at which the transfer belts 19 are pivoted and the carrier material 10 is at a standstill. The transfer the toner images from the transfer modules T1 and T2 the carrier material 10 thus takes place during a start-stop operation of the carrier material 10.

The carrier material 11 is also moved in the paper conveyor belt With the help of motor-driven transport rollers 38. In the area between the transport rollers 38 and the transfer printing stations 24 can charge or corona devices 39 for paper conditioning be arranged so that the paper 10 before Transfer printing, e.g. is set evenly.

So with the start-stop operation mentioned, that is made of paper existing carrier material 10 does not tear and also continuously can be fed, contains the feed module M1 a loop puller 30. This acts as a tape storage Loop puller 30 buffers that from a stacker 31 continuously drawn backing material 10.

After the transfer of both colored toner images in the area of Transfer printing stations 24 on the carrier material 10 have to do this still be fixed. The fixing module M3 serves this purpose. It contains an upper and a lower row of infrared radiators 32, between which the paper transport channel for the Carrier material 10 runs. That is both on the front as well as located on the back of the carrier material 10, toner image fixed by the infrared radiator 32 is still hot and soft and is made according to the infrared steel range 32 via a deflection roller arranged on the output side 33 guided without contact. The fixation takes place by the heat generated by the infrared radiators 32. In a cooling section adjoining the infrared radiator 32 with cooling elements 34 and deflection rollers 35 cooling of the carrier material 10 and smoothing, e.g. via appropriate Decurler facilities. As cooling elements 34 can serve fan-driven air chambers. To Both toner images are fixed and cooled down accordingly Post-processing of the carrier material 10 within of the post-processing module M4, which e.g. a cutting device 36 with stacking device 37 can contain.

In order to be able to implement the different operating states, serves a coupled with the device control GS of the printer microprocessor-controlled control device ST, which with the controlling and regulating components of feed module M1, Print module M2 and fixing module M3 or post-processing module M4 communicates. It is coupled within the modules with the individual units, e.g. with the electrophotography modules E1 and E2 and the transfer modules T1 and T2. Connected to the GS device controller or the controller ST, which can be part of the device control, is a Control panel B, through which the various operating states can be entered. The control panel B can have a touch screen Screen included or a personal computer with paired PC Keyboard. The control itself can be conventional be constructed.

2 contain the Electrophotography modules E1 and E2 two independently of one another working, image-producing devices B1 and B2. The first imaging device B1 contains a character generator 15, a charging device 14, an intermediate exposure device 23, a cleaning device 22, a Unloading corotron device 21 and a developer station 16.1. The second imaging device B2 is analog built with charging device 14, character generator 15, a development station 16/2 and an intermediate exposure device 17. The developer station 16/1 can be a first Color, e.g. black, and the developer station 16/2 a second color, e.g. blue or another Colour. This makes it possible to use the electrophotography modules E1 or E2 first a first toner image Color black and this black toner image with the second imaging device B2 with a toner image overlay the additional color. The overlaid toner image (Spot color toner image) is then applied to the transfer modules T1 and T2 transferred and from there directly to the carrier material 10. This makes it possible to move on to the continuously Carrier material 10 two-tone toner images on both sides apply. Will only be one of the imaging facilities B1 or B2 activated, is printed monochrome continuously. The transfer modules T1 and T2 serve in both operating modes only for transferring the toner images without changing the operating mode "Collect" is necessary. However, it is also conceivable both imaging devices B1 and B2 alternately to actuate and transfer modules T1 and T2 as described at the beginning, to operate in the "Collect" operating mode.

The transfer devices T1 shown in Figures 1 and 2 and T2 belong to the transfer station T, its essential parts are explained below with reference to FIGS. 3 to 21. FIG. 3 shows an exemplary embodiment of the transfer station T, where two transfer rollers are used. The toner image 44 is located on the transfer belt 41 for the front of the carrier material 43. On the second Transfer belt 42 is the toner image 45 for the Back of the carrier material 43, which is preferably a paper web is. Both toner images 44 and 45 are for example using the electrophotographic devices E1 and E2 1 transferred to the transmission belts 41, 42 Service. In the present case according to FIG. 3, a positive Toner system used, i.e. after applying the toner images 44, 45 the toner particles have positive electrical charges, as indicated in Figure 3. Between the two Transfer belts 41, 42, the carrier material 43 is arranged, which is conveyed in the direction of arrow P1.

Guide two electrically conductive transfer rollers 49a, 49b the transfer belts 41, 42 such that they the carrier material 43 touch. There is one on the transfer rollers 49a, 49b DC electrical voltage U applied from a DC voltage source 40 is being fed. In the area of facing each other Transfer rollers 49a, 49b carry out the transfer printing process, in the toner particle from the transfer belts 41, 42 transferred to the respective surface of the carrier material 43 become. This area is also known as the transfer point. In front of the transfer printing station is 42 on the transfer belt a Umladekorotron 47a arranged, which with negative DC voltage to ground from a DC voltage source 48 is fed. The recharge corotron 47a has a ground electrode 47b opposite.

In principle, the transmission bands 41, 42 can be made from one insulating material or made of a conductive material. It is desirable that the transfer belts 41, 42 and the substrate 43 the same surface speeds to have. Too much relative movement of the surfaces a mechanical blurring of the toner images 44, 45 and could have a negative impact on print quality.

Figure 4 shows the operation of the simultaneous transfer printing when using a positive toner system. Because of the Charging corotron 47a generated electric field, the polarity that arranged on the lower transmission belt 42 Reverse toner particles, i.e. have the toner particles 46 no longer a positive charge, but a negative charge, as indicated in Figures 3 and 4. The toner particles of the toner image 44 are still positively charged. Because of the applied to the transfer rollers 49a, 49b Voltage U forms an electrostatic field F, whose field lines depend on the shape of the transfer rollers 49a, 49b, i.e. depending in particular on the radius of curvature. In Figure 4 it is indicated that the electrical Field F in the plane of the central axes of the transfer rollers 49a, 49b is largely homogeneous and along the edge the plane of the carrier material 43 becomes more inhomogeneous. Dependent of the electrical adjustable by the voltage U Field strength detaches the toner particles of the upper toner image 44 from the transmission belt 41 and lie on the front of the carrier material 43. Because of the potential of the upper transfer roller 49a is positive for the toner particles of the toner image 44 have a repulsive force, which the accumulation of the toner particles on the surface of the Carrier material 43 causes. The lower transfer roller 49b has negative voltage potential related to the potential the toner particles 46 with negative charge. Accordingly these toner particles 46 from the surface of the lower transfer belt 42 repelled, walking against the direction of the electric field F to the back of the carrier material 43 and accumulate there.

In the inhomogeneous area, e.g. in the field line F1, des electrical field F, toner particles can occasionally accumulate solve early. Due to the inhomogeneity of the field and due to the increased distance between the surfaces of the carrier material 43 and the transfer belts 41, 42 the impact of the toner particles on the carrier material 43 not exactly determined; it can lead to a nebulizing effect come, which is known under the technical name "Fogging". This effect is discussed in more detail below.

Figure 5 shows an electrical equivalent circuit, which as Circuit with series resistors R is shown. The flowing current i results from Ohm's law, i.e. the current i is the quotient divided by the voltage U. by the sum of the individual resistances R. The aim should be that the resistances R of the two transfer rollers 49a, 49b if possible are small. This can be done using conductive materials be realized, i.e. e.g. transfer rollers made of metal. It should also be provided that the Resistances R of the transmission bands 41, 42 are as large as possible are so that the total current i remains small. With a large total current i becomes namely the wear of the transmission tapes 41, 42 enlarged. The resistance R of the transmission bands 41, 42 must, however, assume a finite value so that the electric field F with high intensity on the surface of the respective transmission bands 41, 42. is namely the resistance R of the transmission bands 41, 42 too is large, so is the effective distance for the electric field F increased; it extends from the surface of the transfer roller 49a to the surface of the transfer roller 49b. at same voltage U is then the field strength within the Field F weakened. With a certain conductivity of the Transfer bands 41, 42 is the effective distance for that electric field F between the transmission bands 41, 42 reduced and thus the field strength with otherwise the same voltage U enlarged.

FIG. 6 shows essential parts of the transfer station T. Use of a negative toner system, i.e. where the charges the toner particles after being applied to the transfer belts 41, 42 are negatively charged. The polarity reversal is in turn caused by the transfer corotron 47a, which in this case, however, has positive potential. Likewise the transfer rollers 49a, 49b are driven with a voltage U, so that an electric field arises, its field strength compared to the exemplary embodiment according to FIG. 3 reverses. The function of the transfer printing corresponds to that described so far, only with the opposite sign of the charge and the field strength.

Figure 7 shows the possible potential relationships on the Transfer rollers 49a, 49b. In Figures 7a and 7b one of the transfer rollers 49a, 49b to ground. Likewise an electrode of the DC voltage source 40 is grounded. Figure 7c shows a symmetrical voltage control, wherein the center of tension is grounded. Figure 7d shows an asymmetrical voltage control for the transfer rollers 49a and 49b.

FIG. 8 shows a development of the arrangement according to FIG. 3. The substrate 43 to be printed is transferred from the transfer rollers 49a and 49b guided so that there are the transfer rollers 49a, 49b in each case by a predetermined wrap angle wraps. This way the area in which the respective toner image 44 or 45 on the surfaces of the carrier material 43 rests, enlarged. inhomogeneities of the electric field F on its edge have less effect strong out; the fogging effect is reduced.

Figure 9 shows an embodiment in which in the feed direction of the carrier material 43 seen in front of the transfer rollers 49a and 49b two guide rollers 49c, 49d are arranged, between which the transmission bands 41 and 42 and that Carrier material 43 are guided. The two guide rollers 49c and 49d are at ground potential while on the transfer rollers 49a and 49b the voltage U for generating the electric field is applied. The two guide rollers 49c, 49d bring the transfer belts 41 and 42 with the Carrier material 43 in contact or reduce the distance a minimum. When the toner images 44, 46 are conveyed forward the inhomogeneous range (see FIG. 4) of the electrical Reach field and first toner particles on the surface of the carrier material 43 are transferred, so is the flight route for these toner particles minimal or zero and there is a precise toner transfer. In this way the mentioned fogging effect is avoided and it becomes a high print quality achieved.

FIG. 10 shows a detailed representation of the transfer printing area Figure 9. The electric field F is between the two transfer rollers 49a and 49b effective. Because of the touch of the toner particles on the transfer belts 41, 42 with the The surface of the carrier material takes place in an electrical field 41 a precise transfer printing.

Figure 11 shows a variant of the embodiment Figure 9. The lower transfer roller 49b and the upper guide roller 49c are subjected to a voltage potential, so that the electric field F between the rollers 49b and 49c is effective. The transfer roller 49a and the Guide roller 49d are insulated and have a floating Potential. Due to the measures mentioned, it is possible to reprint required electric field F on a longer one Distance effective, so that the transfer printing process runs more gently, because the effective area on which the transfer of the Toner particles from the transfer belts 41, 42 to the Surface of the carrier material 43 takes place, is enlarged.

FIG. 12 schematically shows the physical relationships using an electrical equivalent circuit diagram. If the specific material resistance p of the transmission bands 41, 42 used is low, then relatively high currents i result due to Ohm's law. With a fixed voltage U this can result in an undesirably high electrical power P according to the relationship: P = U · i.

Due to the inhomogeneity of the materials for the transfer belts 41, 42, local current peaks are possible which briefly break down the electric field and thus interfere with the process of transfer printing. By increasing the distance between the rollers that form the electrodes for the electrical field, the electrical resistance R of the transfer belts 41, 42 and also that of the carrier material 43 increases. Accordingly, the flowing current i decreases due to the relationship R = ρ1 / A, where R is the total electrical resistance, p is the electrical specific material resistance of the transfer belts, 1 is the effective material length and A is the effective material cross section.

Figure 13 shows a combination of the embodiments Figures 9 and 11. In front of the guide rollers 49c and 49d two feed rollers 49e and 49f arranged between which the Transfer belts 41, 42 and the carrier material 43 out are. The feed rollers 49e and 49f carry ground potential, while the arrangement of the rollers 49a, 49b, 49c, 49d and the Potential management corresponds to that of Figure 11. On in this way arises in the area of the feed rollers 49e, 49f an electrically neutral zone, the attraction of Neglect toner particles with different potential is. Early skipping of toner particles in the Area of increased distance between the transfer belts 41, 42 is avoided.

Figure 14 shows a variant of the arrangement of Figure 9. Instead of the grounded guide rollers 49c, 49d are grounded Deflection bracket 49g, 49h used. This deflection bracket 49g, 49h can be placed near the transfer roller 49a, 49b whereby the length of contact of the transfer tapes 41, 42 shortened with the carrier material 43. If you compare them Arrangement according to FIG. 9 with that according to FIG. 14 is too recognize that in Figure 9 the minimum path in which contact between the transfer belts 41, 42 with the carrier material 43 is the sum of the radii of the transfer rollers 49a and 49b and the guide rollers 49c and 49d. If there are speed differences dv between the speed the transfer belts 41, 42 and the carrier material 43 occur, this leads to a mechanical Slip and thus to an undesirable blurring of the transferring toner images. The longer the contact path, or the greater the difference in speed, the greater is the wipe effect. Reducing the speed difference between the transfer belts 41, 42 and the carrier material 43 is hardly possible in practice because of length tolerances must be compensated for preprinted forms. Around Nevertheless, keeping the wiping effect small is according to the exemplary embodiment 14 the length of the contact of Transfer belt 41, 42 and the carrier material 43 reduced, by using narrow deflection brackets 49g, 49h, the Sliding surfaces near the surface of the transfer rollers 49a, 49b can be arranged. To reduce frictional forces, it makes sense to use the deflection bracket 49g, 49h with a friction-reducing Layer, e.g. with a Layer of a fluorine-containing plastic material, e.g. PFA, ETFE, FEP, PVDC, Teflon or polyimide (PI). The surface wear the deflection bracket 49g, 49h can thereby be reduced that hard, wear-resistant materials, e.g. Chrome-nickel steel, VA steel are used, or that the Deflection bracket 49g, 49h with a layer of wear-reducing Material, e.g. by nickel plating, by using silicate or by means of surface hardening.

FIG. 15 shows the current conditions in the example according to FIG. 14, the deflection brackets 49g, 49h being at ground potential. The total current Iges results from the sum of the currents Ium at the transfer pressure point and the cross currents Iq1 and Iq2. The aim should be that Ium >> Iq1 + Iq2 is or that Iq1 = Iq2 = 0 is. If the cross-current components Iql, Iq2, which flow through the transmission belts 41, 42 directly into the earthed deflection brackets 49g, 49h, are undesirably high, the deflection brackets 49h, 49g can also be arranged in an electrically insulated manner so that they assume floating potential (cf. Figure 16).

Figure 17 shows an embodiment in which the deflection bracket 49g, 49h are electrically conductive, but via a resistor R are led to ground potential. This too Embodiment according to Figure 17, the cross currents are reduced.

Figure 18 shows a variant of the embodiment Figure 13. The feed rollers 49e, 49f are through deflection brackets 49i, 49j replaced. These deflection brackets 49i, 49j can be electrical be designed as in the examples according to the Figures 16 and 17 is indicated.

Figure 19 shows various embodiments for the transfer rollers. In the upper part of the picture, the transfer roller is cylindrical and made of an electrically conductive metal as a solid component. In the middle section of FIG. 19, the transfer roller is made of metal from a tube, ie hollow inside. The lower part of the figure in FIG. 19 shows a metallic core, which can consist of solid material or of a tube. This core is covered with a jacket made of high-resistance material. The use of a metallic core for the transfer roller is expedient since it has to be manufactured very precisely with little out-of-roundness. In order to minimize runout errors, the circumference of the transfer roller and the length of the transfer belt should be in an integer relationship. However, the transfer belts have a certain fluctuation in thickness, which interferes with the transfer printing process, for example local detachment of the transfer belts from the roller can occur. Therefore, an elastic coating is advantageously applied to the transfer roller, which can compensate for small mechanical tolerances of the components by elastic deformation. This coating should have an electrical conductivity in order to be able to build up a strong electrical field in the transfer printing zone on its outer skin. The electrical conductivity of the coating should be in the range from 0.5 x 10 ^-6 to 5 x 10 ¹² Ωcm, but preferably in the range from 0.5 x 10 ⁵ to 5 x 10 ⁹ Ωcm. The elastic coating should have a Shore hardness in the range from 10 to 90 Sh (A), preferably in the range from 20 to 70 Sh (A). The thickness of the elastic coating is 0.2 to 15 mm, preferably 0.5 to 2 mm. The elastic coating can additionally have a layer of fluorine-containing plastic material, preferably of PFA, ETFE, FEP, PVDC or Teflon, or of a polyimide layer. The additional layer can also be electrically insulating and have a maximum thickness of 40 μm, preferably from 0.1 to 20 μm. Conductive fillers, preferably carbon black, silicates, oxides, can be added to the elastic layer, which enables an increased layer thickness.

Figure 20 shows a transfer roller that has no continuous has metallic core, but lateral metallic contact cylinder 50. The central part 52 of the cylindrical The roller consists of a high-resistance material. In the figure the resistance R is plotted over the length 1 of the roller. It can be seen that the resistance R increases with increasing length 1 increases, whereby the local current i over the length 1 at applied voltage U drops. It thus result along the length 1 different potentials, which is undesirable.

Figure 21 shows an embodiment of a transfer roller with a low-resistance, metallic core 56 on which one Coating 54 is applied, which is a relative high-resistance material. Along length 1 the Resistance R constant, which also extends along length 1 a constant potential on the surface of the high impedance Coat coating results. The core can also be electrical conductive plastic, e.g. from the Material PA that contains soot particles.

In Figure 22 is a Umladekorotroneinrichtung 110 with two Corotron wires 112 and with two blades Counter electrodes 114 shown. As an intermediate carrier is a Photoconductor tape 116 is provided. But it can also be a transfer belt be used.

The photoconductor belt 116 with a toner image that has not yet been fixed 118, the positively charged toner particle 120 or after of the charge contains negatively charged toner particles 122 between the two corotron wires 112 and the two counter electrodes 114 performed, it being guided by deflection rollers 124 and is driven. The blades 114 are on one Bracket 126 attached, which is also the electrical connection to the ground potential of the printing and / or copying device 128 manufactures. The corotron wires 112 are on the photoconductor tape 116 opposite side surrounded by two screens 130. The photoconductor tape 116 is spaced in the range of 0.2 mm to 4 mm, preferably in the range from 0.2 mm to 1 mm, passed the counter electrodes 114. The negatively charged Toner particles 122 of the latent toner image 118 become by the electric field between the corotron wires 112 and recharged the counter electrodes 114.

FIG. 23 shows a recharging corotron device 110 with a corotron wire 112 and a single blade used as counterelectrode 114, the field lines 132, 134 of the effective electric field being indicated. The effective area, on which the magnitude of the attractive force between the photoconductor band 116 and the counter electrode 114 depends, is designated by 136. The counter electrode 114 has ground potential. Alternatively, the counter electrode can have a negative potential with respect to the ground potential. An electric field is formed between the corotron wire 112 and the counter electrode 114. This field 134 acts on the toner particles 122 which have a negative potential. The toner particles 122 are discharged as they pass the corotron wire 112 and charged to a positive potential. The magnitude of the potential of the now positively charged toner 120 depends on the duration of the toner in the electric field and on the density of the electric field. The photoconductor tape 116 is attracted by the counter electrode 114. The attraction F is determined from the relationship: F = ε 0 · Ε r · A · U 2 2 · d 2 . where ε _{r is} the dielectric constant of the air between photoconductor band 116 and counter electrode 114, A is the surface 136 of the counter electrode 114 effective in the electric field, U is the potential difference and d is the distance between the underside of the photoconductor band 116 and the counter electrode 114.

Another counter electrode 114 is shown in FIG. which is designed as a blade. This blade 114 has one rectangular cross section and is by a holder 126 in Printer and / or copier 128 attached.

In Figure 25, a blade 114 is shown, the cutting edge is jagged. The blade 114 is in the printer / copier 128 arranged so that the teeth 140 in the direction of the photoconductor belt 116 taper. The tines 140 are equidistant arranged. This arrangement ensures even transhipment of the latent toner image 118 guaranteed. The keeper 126 of the blade 114 is not shown in this figure 25.

FIG. 26 shows a counter electrode 114 which consists of an arrangement of single pins 142. Pins 142 are arranged on a holder 126 at symmetrical intervals. The holder 126 is so in the printer and / or copier 128 arranged that the ends of the individual pins 142 in a parallel Level to the photoconductor tape 116 or to the corotron wire 112, and lie parallel to the corotron wire.

FIG. 27 shows a counter electrode 114 which consists of there is a wire 144. The wire 144 is replaced by a suitable one Holding device 126 in the printer and / or copier 128 so arranged that it is in a plane parallel to the photoconductor belt 116 and parallel to the corotron wire 112. On the is the side of the wire 144 facing away from the photoconductor band 116 a screen 130 is arranged. The wire 144 is a corotron wire 112 similar wire 144 inserted.

FIG. 28 shows a transfer printing corotron device 146 with a Corotron wire 112 and with a blade 114 Counter electrode shown. There are two photoconductor tapes as intermediate supports 116a and 116b are provided. But it can alternatively two transfer belts can also be used. One more unfixed toner image 118a on the photoconductor belt 116a contains positively charged toner particles 120. Not yet contains fixed toner image 118b on the photoconductor belt 116b negatively charged toner particles 122. The photoconductor tapes 116a and 116b and a paper web 148 are between the corotron wire 112 and the blade 114 without touching them performed, the photoconductor belts 116a, 116b by deflection rollers 124 are guided and driven. The drive and the guidance of the paper web 148 is not in this figure shown. Corotone wire 112 has a positive potential and blade 114 has a negative potential to the ground potential. The corotron wire 112 is on the Photoconductor tape 116a facing away from a screen 130 surround. The positively charged latent toner particles 120 Toner image 118a are from the positively charged corotron wire 112 repelled and from the negatively charged toner particles 122 of the latent toner image 118b and of the negatively charged one Blade 114 tightened. Similarly, they become negative charged toner particle 122 of the latent toner image 118b of the negatively charged blade 114 and repelled by the positively charged toner particles 120 of the latent toner image 118a and attracted by the positively charged corotron wire 112. On the positively and negatively charged toner particles 120, 122 acts through the transfer corotron 146 a force that is greater than the binding forces between the toner particles 120, 122 and the photoconductor tapes 116a, 116b. The positive and negatively charged toner particles 120, 122 are replaced by the Field forces of the electric field are printed on the paper web 146. The toner particles remain on the paper web 146 120, 122 by the binding forces between the toner particles 120, 122 and the paper web 146 as well as by the attraction between the positively charged toner particles 120 one side of the paper and the negatively charged toner particles 122 stick on the other side of the paper.

LIST OF REFERENCE NUMBERS

M1

feeder module

M2

print module

M3

fuser

M4

post-processing

10

Record carrier, paper, single sheet or continuous paper

11

transport channel

E1

Electrophotography module, front

E2

Electrophotography module, back

T1

Transfer module, front

T2

Transfer module, rear

12

deflection rollers

13

photoconductor

14

loader

15

character generator

16/1 to 16/5

developer stations

17

Between exposure device

18

Transfer device, transfer area

19

transfer tape

20

Transfer corona device

21

Endladekoronaeinrichtung

22

cleaning station

23

Between exposure device

24

transfer station

25

deflecting

26

cleaning station

27

deflecting

28

transfer printing

29

Umdruckkorotron

30

loop puller

31

stacker

32

infrared Heaters

33

deflecting

34

cooling element

35

deflecting

36

cutter

37

stacker

GS

device control

ST

control device

B

control panel

38

transport rollers

39

Charging corona device

B1

Imaging facility

B2

Imaging facility

40

DC voltage source

41

upper transmission band

42

lower transfer belt

43

support material

44

toner image

45

toner image

46

reloaded toner particles

47a

Umladekorotron

47b

ground electrode

48

DC voltage source

49a, 49b

transfer rollers

49c, 49d

guide rollers

49e, 49f

feed rollers

49g, 49h

guide yoke

49i, 49j

Deflection bracket guided against ground

P1

transportation arrow

T

transfer station

50

contact

52

midsection

54

coating

56

core

F

electric field

F1

field line

R

resistance

U

tension

i

electricity

1

length

A

effective area

ρ

specific resistance

110

Umladekorotroneinrichtung

112

corotron

114

counter electrode

116

Photoconductor belt

118

latent toner image

120

positively charged toner particles

122

negatively charged toner particles

124

deflecting

126

holder

128

Printing and / or copying device

130

umbrella

132

field lines

134

field lines

136

effective area of the electric field counter electrode

140

Pink

142

Single pins

144

wire

146

Umdruckkorotron

148

paper web

Claims (16)

Printing or copying device with a corotron device (110),
with at least one corotron wire (112) with a first potential,
with at least one counter electrode (114) with a second potential different from the first potential,
and with at least one intermediate carrier (116) for toner images, which is guided between the corotron wire (112) and the counter electrode (114),
characterized in that
the counter electrode (114) has electrically conductive elevations (140, 142), the end points of which protrude in the direction of the corotron wire (112) and which lie in a plane parallel to the longitudinal axis of the corotron wire (112) and parallel to the intermediate carrier (116). Device according to claim 1, characterized in that these elevations (140, 142) run parallel to the longitudinal axis of the corotron wire (112). Device according to one of the preceding claims, characterized in that the counter electrode (114) contains single pins (142) as elevations. Device according to one of the preceding claims, characterized in that the counter electrode (114) contains tapered elevations (140, 142). Printing or copying device with a corotron device (110),
with at least one corotron wire (112) with a first potential,
with at least one counter electrode (114) with a second potential different from the first potential,
and with at least one intermediate carrier (116) for toner images, which is guided between the corotron wire (112) and the counter electrode (114),
characterized in that
the counter electrode (114) is designed in the manner of a blade with a cutting edge, the cutting edge being arranged parallel to the longitudinal axis of the corotron wire (112). Device according to claim 5, characterized in that the cutting edge is serrated and that the end points and / or end faces of the serrations (140) project in the direction of the corotron wire (112) and are parallel to the longitudinal axis of the corotron wire (112). Device according to claim 6, characterized in that the teeth (140) taper in the direction of the corotron wire (112). Device according to one of the preceding claims 5 to 7, characterized in that the cross section of the blade (114) tapers in the direction of the corotron wire (112). Device according to one of the preceding claims 5 to 8, characterized in that the cutting edge has a width which is in the range from 0.02 mm to 0.5 mm, preferably in the range from 0.02 mm to 0.1 mm. Printing or copying device with a corotron device (110),
with at least one corotron wire (112) with a first potential,
with at least one counter electrode (114) with a second potential different from the first potential,
and with at least one intermediate carrier (116) for toner images, which is guided between the corotron wire (112) and the counter electrode (114),
characterized in that
the counter electrode (114) is designed as a wire (144), the longitudinal axis of the wire (144) being arranged parallel to the longitudinal axis of the corotron wire (112). Device according to one of the preceding claims 1 to 10, characterized in that the corotron wire (112) and the counter electrode (114) lie in a plane which is perpendicular to the intermediate carrier (116). Device according to one of the preceding claims, characterized in that the intermediate carrier (116) is a photoconductor belt or a transfer belt. Device according to one of the preceding claims, characterized in that the corotron device (110) is a reloading corotron, a loading corotron, a transfer printing corotron or an extinguishing corotron. Device according to one of the preceding claims, characterized in that the intermediate carrier (116) at a distance in a range from 0.2 mm to 4 mm, preferably in a range from 0.2 mm to 1 mm, on the counter electrode (114) is led past. Device according to one of the preceding claims, characterized in that the counter electrode (114) has ground potential. Device according to one of the preceding claims, characterized in that the intermediate carrier (116) consists of a high-resistance material which has a specific resistance of> 10 ⁶ ohm cm.

Images