EP0713155A2 - Dispositif d'impression anisotrope et méthode - Google Patents

Dispositif d'impression anisotrope et méthode Download PDF

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Publication number
EP0713155A2
EP0713155A2 EP95117918A EP95117918A EP0713155A2 EP 0713155 A2 EP0713155 A2 EP 0713155A2 EP 95117918 A EP95117918 A EP 95117918A EP 95117918 A EP95117918 A EP 95117918A EP 0713155 A2 EP0713155 A2 EP 0713155A2
Authority
EP
European Patent Office
Prior art keywords
recording surface
points
recording
dielectric
write head
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP95117918A
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German (de)
English (en)
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EP0713155A3 (fr
EP0713155B1 (fr
Inventor
Hermann Dr. Statz
Anton Rodi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RODI, ANTON
Original Assignee
Heidelberger Druckmaschinen AG
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Publication of EP0713155A2 publication Critical patent/EP0713155A2/fr
Publication of EP0713155A3 publication Critical patent/EP0713155A3/fr
Application granted granted Critical
Publication of EP0713155B1 publication Critical patent/EP0713155B1/fr
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/32—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head
    • G03G15/321—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head by charge transfer onto the recording material in accordance with the image
    • G03G15/325—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head by charge transfer onto the recording material in accordance with the image using a stylus or a multi-styli array
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/385—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material
    • B41J2/39—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material using multi-stylus heads
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/32—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head
    • G03G15/321—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the charge pattern is formed dotwise, e.g. by a thermal head by charge transfer onto the recording material in accordance with the image

Definitions

  • the invention relates to an apparatus and method for printing, more particularly to an apparatus and method for electrophoretic and dielectrophoretic printing.
  • Digital systems for producing print media have become widespread in the field of graphic printing.
  • the systems typically work with a digital database, based on the printing forms, and either on a plate that is then mounted in a press or deposited on the press roll of a press.
  • the print information can be recorded in the form of binary signals, which together represent the "signature image".
  • These plates or rollers are always separated according to the main color components of the original image, e.g. cyan, magenta, yellow and black.
  • the color components can be obtained sequentially or simultaneously with parallel recording heads.
  • the recording heads used in prior art devices are characterized by: 1) several laser beams which travel across the plate or cylinder line by line at high speed, 2) several laser diodes which spiral through the recording medium when writing several lines, or 3) groups (arrays) of light-emitting diodes (LEDs) for the serial recording of a spiral-shaped pattern, which represents a single-color sheet.
  • groups (arrays) of light-emitting diodes (LEDs) for the serial recording of a spiral-shaped pattern, which represents a single-color sheet.
  • the recording medium is light-sensitive in each case, and this always requires a light-tight recording and pressure chamber in order to prior art devices to prevent accidental exposure of the recording medium.
  • the first method uses a waterless method for picking up offset ink and then transferring it to the printing substrate.
  • the second method uses a special, liquid electrostatic toner made of charged particles, and these particles are electrostatically deposited on the printing component and from there on an offset cloth, which in turn transfers the toner electrostatically to a sheet of paper or other printing medium.
  • dry toner is xerographically deposited on the photosensitive printing component, from where the toner is transferred directly to the printing medium using a standard xerographic method.
  • systems that use charged toner typically require relatively large toner particles, i.e. above or at least equal to 5 microns so that the toner particles can carry a uniform charge.
  • Printing devices are also known which operate with a printing roller which acts both as an electrode and as a dielectric signal storage component works.
  • the platen has a heated, dielectric, low color phobic recording surface in rolling contact with a platen that can carry a print medium such as paper. Beneath this dielectric surface is a conductive layer that acts as an electrode when an image is written or recorded on the platen.
  • a writing station with a printhead, an inking station via which different-colored thermoplastic printing inks can be dispensed, and an ink transfer station, which is actually the gap between the two rollers.
  • a printhead responsive to incoming data is stored on the platen while successive revolutions of the same emit electronic latent images representing the color components or signatures of an original image, and each such image consists of a pattern of electrostatic charge areas or dots, the field strengths of which correspond to Gray or color values vary.
  • this charge pattern is transported to the application station, at which a heated application head presents the surface of the plate cylinder with successive revolutions of the cylinder, special thermoplastic printing inks, the actual colors of which, as a rule, but not necessarily, match the colors of the surface mentioned images recorded on the printhead. These colors usually include cyan, magenta, yellow and black in subtractive color printing.
  • the field lines from the electrostatic charge areas or pixels that make up the latent image cause "pieces" of the melted ink to be removed from the application head.
  • the field lines can change briefly as they pass under the application head or not, depending on the presence of earthed or pre-stressed components of the application head.
  • the quantities The color elements are directly proportional to the field strengths of the charge areas.
  • the colors - still in the molten state on the printing roller - and the relatively cool paper on the paper roller are rotated through the gap between the two rollers.
  • the ink changes phase so that the color changes from a liquid state to a solid state, so that the ink is immediately transferred to the paper.
  • This adhesion and the color-phobic nature of the roller surface overcome the electrical forces that hold the ink on the plate cylinder, so that essentially complete transfer of the ink takes place where the ink touches the paper.
  • the image printed on the paper of the paper roll corresponds exactly to the latent image embossed on the plate cylinder.
  • a printing device of the above type is described, for example, in U.S. Patent 5,325,120, the content of which is hereby incorporated by reference.
  • the printing component has an anisotropic recording surface, so that the electrostatic charge areas generated on this surface by the print head are uniform or result in inhomogeneous electrostatic fields at the location of each picture element (pixel), with a field beyond the surface of the printing component. If these charged areas of the printing component are moved against the development medium, ie dielectric printing ink or toner, the field induces an electrical dipole moment in the medium in question by dielectric polarization. The polarized medium obtained is drawn through the field gradient to the area of maximum field strength.
  • the polarization charge at one end of the medium in the stronger field is pulled more towards the stronger field, while the opposite and equal polarization charge at the other end of the medium is pushed back less strongly in the other direction because the field there is weaker.
  • the development medium thus migrates to the areas of the pressure component in which the fields are strongest and adheres there.
  • Dielectrophoretic printing therefore enables electrostatic printing without the need for charged ink or charged toner particles.
  • such an uncharged medium is not bound to the surface by image charge attraction or by interactions with a charge-induced polarization of the dielectric printing roller. For this reason, it is easier to obtain a clean, fog-free developed image on the printing roller than is possible with the images developed using electrically charged printing inks or toner particles.
  • a uniform electric field on the dielectric surface of a printing component can be applied to various Because of being won.
  • a printing component such as a printing roller
  • the Dr. Kuehnle provides for writing on the surface with a wire on which there is a periodically varying voltage, for example alternating voltage or rectified alternating voltage (direct voltage), the amplitude of the voltage varying in accordance with the digital input signal on the printing device.
  • the uniform field for the printing component can be brought about by the structure of the printing component itself.
  • the printing component can be provided with a dielectric surface that is anisotropic in that it contains a pattern of conductive paths that extend from the surface of the dielectric layer to a ground plane below that layer.
  • One way to obtain these grounded areas or field endpoints on the dielectric layer is to form the layer so that it contains many crystallites with so-called grain boundaries, the electrical conductivity of which is considerably greater than that within the crystallites themselves.
  • the charges on the surface of the printing component are arranged in such a way that a maximum field strength is achieved around each grounding point with a steep drop in the field strength between the grounding points .
  • a pressure component such as that described would be desirable, the anisotropy of which does not depend on the morphology or molecular structure of the dielectric layer.
  • U.S. Patent No. 5,315,061 describes a donor or development roller for transferring a charged toner onto a photoconductor belt for developing a latent image on the photoconductor belt.
  • the donor roller is made of metal and small dielectric bodies are distributed over the surface. When friction is charged on the entire surface of the donor roller, electrostatic fields are formed between the dielectric bodies and the metal surface. Small closed electric fields - so-called "microfields" - are thus formed on the surface of the donor roller. These microfields help attract the charged toner to the surface of the donor roller. A squeegee then sets the toner to a uniform thickness.
  • the donor roller of U.S. Patent 5, 315,061 provides a homogeneous and uniform amount of charged toner to allow development of an image on a photoconductor belt. No images are written directly on the donor roller, rather the images are written on the photoconductor tape.
  • U.S. Patent No. 3,739,748 shows a donor roller for transferring charged toner onto a xerographic drum.
  • the donor roller has a dielectric surface which is contacted by pins connected to a voltage source.
  • the pens cannot write images on the donor roller, but rather only facilitate the gray value reproduction of the image which is written on the xerographic drum by an exposure device.
  • the present invention accordingly aims to provide an optoelectric printing device, the printing component of which has an anisotropic dielectric recording layer. Another purpose of the invention is the indication of such a device that is relatively easy to manufacture.
  • Another purpose of the invention is to provide such a device in which strong inhomogeneous fields can be maintained over the surface of the pressure component.
  • Another purpose of the invention is to provide a device with a printing component on which electronic images can be recorded with very good resolution.
  • Another purpose of this invention is to provide effective write heads in conjunction with a dielectric surface that can record electronic images with very good resolution.
  • the printing component includes a substrate that supports a thin layer of dielectric material, the resistivity of which is very high, for example about 1015 ohms / cm, to prevent premature discharge.
  • a conductive layer can be provided in the middle between the substrate and the dielectric layer. This conductive layer can be grounded or can remain ungrounded, as will be described below in connection with the various embodiments.
  • a pattern of minute conductive areas or dots may be present on the work surface or within the dielectric layer. If present, the dots are preferably arranged periodically with a period at least equal to or smaller than the size of a resolution element or picture element (pixel) of the electronic image that is to be recorded on the printing component.
  • the conductive dots are made of a material with a smaller resistivity than that of the dielectric preferably of a metallic type, but in certain applications can also be electrically connected to the conductive level below the dielectric layer.
  • an adhesive coating covers the surfaces of the dielectric layer and the conductive dots, so that the recording surface of the printing component is slightly ink-phobic.
  • the cross sections of the points can be circular, but various other shapes are also possible, including rectangular or toroidal.
  • electrical charges can be applied to the recording surface of the print component by a microtunnel type print or write head as described in U.S. Patent No. 5,325,120.
  • these charges represent an image recorded on the print component.
  • These charges result in uniform electric fields that are strongest around the conductive dots.
  • the mean voltage around each point is also a monotonous function of the gray value at the relevant point in the electronic image.
  • the uniform fields generated by the conductive dots on the dielectric surface of the recording component extend beyond the surface.
  • a dielectric development medium such as ink or toner
  • the electric fields induce an electric dipole moment in the medium by dielectric polarization, and the medium becomes proportional to the strengths of the charged surfaces of the recording surface by dielectrophoresis Charges pulled.
  • the development medium thus accumulates around each conductive point in an amount that increases monotonically with the field strength at the location in question, thereby developing the electronic image recorded on the printing component.
  • Similar non-uniform fields can be obtained on a print component whose conductive dots are not grounded, using a print or write head, as will be described later, which has multiple electrical contacts that carry image-dependent voltages. In this case, the relatively strong fields around the points decrease steeply with increasing distance from the points.
  • Such an electrical contact print or write head can also be used to generate positive and negative charges that charge the dielectric surface, as will be described later.
  • Uneven fields can also be obtained by writing directly to a dielectric surface with or without dots using a write head similar to the electrical contact write head, but using alternating current instead of direct current.
  • a write head similar to the electrical contact write head, but using alternating current instead of direct current.
  • an ungrounded conductive layer can be provided below the dielectric layer, as will be described later.
  • the dots and any paths or other connections to the ground plane in the dielectric position of the pressure component can be formed using methods of conventional circuit board technology.
  • the printing components can thus be manufactured relatively inexpensively in large numbers.
  • printing components such as the described are likely to find widespread use in feeding and other printing devices for dielectrophoretic and electrophoretic printing.
  • the printing device includes a rotary roller 10 for holding a printing medium such as the paper web W.
  • a printing roller 12 is arranged parallel to the roller 10 in such a way that its cylindrical surface just touches the web W.
  • an electronic print or write head 14 Around the pressure roller 12 are provided: an electronic print or write head 14, an ink application head 16, which offers the plate roller a dielectric, electrically uncharged ink, an ink transfer station 18 formed by the nip, and an erase head 22, all of which functions are controlled by a control device 24 .
  • the control device 24 receives input signals in the form of a digital data stream for the gray or color values of an image to be reproduced.
  • FIG. 1 a single printing unit for printing a single color component or signature of an original document, e.g. Cyan component.
  • three further printing units are arranged behind the roller 12 for printing the other color components, namely magenta, yellow and black, as shown, for example, in U.S. Patent 4,792,860, the content of which is hereby incorporated by reference.
  • the device according to FIG. 1 print all four color signatures as modified for a multi-color application station, as described, for example, in U.S. Patent 5,325,120.
  • the data representing the different color components of a color original are fed to the device in the form of successive streams (chains).
  • the system can receive the data in the order of cyan, magenta, yellow, and black.
  • a mass storage device 24a is preferably used in connection with the control device 24 for storing the relatively large amounts of data that are required to operate the device.
  • the control device 24 controls the print head 14 such that when the print roller 12 rotates, the print head records electrostatic images on the roller surface 12a in accordance with at least one of the color components, as shown in the incoming data stream.
  • the printhead can be a microtunnel head as specified in U.S. Patent 5,325,120.
  • the application head 16 can be constructed like that described in the patent specification 4,792,860 or 5,325,120. It provides a melted thermoplastic ink made from pigment particles in one of the four inks dispersed in a binder.
  • the platen surface 12a is preferably weakly color phobic so that the ink does not tend to adhere to the surface of the platen except at the locations charged by the printhead 14. If, for example, a cyan image is written on the printing roller 12, the application head 16 supplies cyan ink.
  • the amounts of ink picked up or detected by the charged areas on the roller surface 12a increase monotonically with the field strengths emanating from these charged areas. This variation of field strengths across the image on the printing roller surface 12a facilitates the reproduction of the complete gray scale area.
  • the roller 26 rotates further, the developed area of the image is transported on the surface 12a to the application station 18, which consists of the gap between the rollers or cylinders 10 and 12.
  • the control device 24 controls the position of the image on the roller 12 so that after this image has been developed and transported through the nip, the image developed thereon is transferred to the correct position on the web W.
  • the charged areas of the roller surface 12a can be transported past the erasing station 22.
  • This station can be funds, e.g. an ultraviolet lamp 22a is included to render the roller surface 12a conductive so that the charges thereon are dissipated.
  • the device according to FIG. 1 differs from the devices described in the above patents in that its platen roller 12 has an anisotropic recording surface so that the electrical charges caused by the printhead 16 during a write operation are unevenly distributed on the platen surface 12a to thereby produce uneven electric fields that extend beyond the surface of the roller.
  • the charged areas pick up ink from the applicator head by dielectrophoresis.
  • the ink particles are polarized by the unevenly charged roller surface 12a where the fields are strongest in amounts that increase monotonically with the field strengths in these charged areas.
  • roller 12 includes a rigid core 32, which may be made of steel or aluminum, and this core is preferably slotted as shown to reduce its weight and thereby allow air to cool through the core can circulate.
  • a sleeve 34 is arranged around the core 32, for example made of a material such as ceramic material, which is thermally and electrically well insulated.
  • Anisotropy of layer 38 is achieved by providing a pattern of conductive points 42 in layer 38 that are electrically connected to conductive layer 36.
  • the grounded dots can be formed, for example, by forming a pattern of minute through holes in the layer 38 in the thickness direction and filling the holes with conductive material such as metal or polysilicon.
  • these points 42 in the figures of the drawings are shown relatively large and at a large distance. In reality, however, the points can never have a diameter of less than 1 ⁇ m and are only a few ⁇ m apart.
  • the dots 42 in the roller 12 are arranged in columns and rows at right angles, e.g. 10 x 10 dots per picture element (pixel).
  • the dot pattern for each picture element (pixel) should be periodic for best results.
  • the roller 12 is preferably also provided with a very thin outer coating 44 made of an adhesive material such as polytetrafluoroethylene (Teflon) or others that are color phobic.
  • This surface adhesion coating prevents ink from adhering to uncharged areas of roller surface 12a and also minimizes ink smear on that surface.
  • the ions tend to migrate through the openings of the microtunnels and are attracted there by the electrically grounded layer 36 of the pressure roller 12.
  • the incoming positive charges accumulate on the recording surface 12a of the roller 12 so that areas of charge are applied, each of which has a specific Coulomb charge density corresponding to the bias of the control electrode, if any, in connection with the corresponding micro tunnel.
  • the plasma in the microtunnels can be caused to "exit" at the end of the microtunnels by appropriately increasing the tunnel currents.
  • the plasma can be thought of as a gaseous "wire” that charges the dielectric surface to the plasma potential.
  • these bias levels can be digitally adjusted so that the individual microtunnels are separately activated and controlled by the controller so that electrostatic images are generated from imagewise patterns of the charge on the roller surface 12a.
  • a feature of this invention is that when roller 12 is written to by printhead 14, the surface of sheet 38 is passed unevenly through each micro-tunnel of the printhead.
  • the presence of the grounded points 42 causes the surface tension of the roller to periodically decrease to zero volts.
  • each picture element (pixel) of the electronic image on the platen 12 consists of a microscopic pattern of unevenly distributed charge areas, the uneven electric fields cause - so-called micro-fields - which extend outward from the roller surface 12a; but these charges are averaged across the picture element (pixel), so that macroscopically the charge is proportional to the gray or color value for the picture element (pixel) in question.
  • the non-uniform electric field at each spot polarizes the development medium and causes ink particles to be drawn to roller surface 12a by dielectrophoresis in an amount that is monotonous with the charge of each Point increases. Printing ink does not adhere to uncharged areas of the roller surface 12a, in particular not because the adhesive layer 44 is present.
  • Writing heads other than the micro tunnel writing head described above can also be used to apply charges to the dielectric surface, but the micro tunnel writing head is preferred when the dots are grounded, as shown in FIG. 2 shown.
  • the grounded points of FIG. 2 do not have to be directly grounded, rather it is sufficient to connect to the ground plane through materials with a lower resistance than the dielectric.
  • the dots could also be embedded in the dielectric, as long as defined areas are formed on the recording surface, the potential of which is closer to the ground potential.
  • a grounded layer can be provided beneath the dielectric material so that the dielectric material can be charged between the charged point and the grounded layer and how a capacitor works. The dot retains much of its charge when the printhead moves away from it. The dielectric material on the surface around the point remains approximately uncharged or only very weakly charged. Microfields are thus formed between the charged point and the uncharged dielectric on the surface.
  • roller 52 has a core 32, a ceramic sleeve 34 and a conductive layer or ground plane 36.
  • a dielectric layer 54 is formed with a pattern of conductive areas or points 56 on her. These points are not connected to the conductive layer 36.
  • the dots may be embedded on the dielectric material 54 or, less preferably, entirely provided therein, but the recording surface should have areas with a higher conductivity than that of the normal dielectric layer 54, which can still retain a charge when the Printhead moves away.
  • the roller 52 can also have an outer adhesive coating 60, the surface of which represents the recording surface 52a of the roller 52. In this embodiment, however, it is preferred that the points or defined areas with higher conductivity can be connected directly to contacts of the write head.
  • FIGS. 4 and 5 show a print head 72 with a linear group of wire-like contacts or voltage feed points 74, which can run over the entire width of the printing roller.
  • the contacts or voltage feed points 74 are "scratched" and the printhead 72 may be arranged so that the contacts resiliently abut the recording surface 52a of the platen 52 at locations of the conductive dots 56 thereon. Image-dependent voltages are then applied to the various contacts 74 when they face the conductive dots 56 so that the dots are charged.
  • Each contact 74 can be quite small, for example several contacts within the width of a picture element (pixel), because only the corresponding point 56 has to be contacted very briefly (order of magnitude nanoseconds) in order for the conductive point to be fully charged to the full potential of the corresponding contact becomes.
  • the contact can also be as wide as a picture element (pixel), and a single contact can also make contact with more than a single point.
  • Conductive point 56 thus serves as one plate of a capacitor, ground plane 36 as the other.
  • the dielectric between the point and the ground plane can thus be charged by the write head.
  • the dielectric material under the point and the connection point retain a charge, and thus field lines extend across the charged points and the substantially uncharged surrounding dielectric. In this way, microfields are formed that attract ink around the dots.
  • the effectiveness of the printing roller is considerably increased by the presence of the points, because stronger fields can be generated than with wire-like contacts on a flat dielectric surface. In general, it can be roughly assumed that practically no charge remains on the non-metallized dielectric when using narrow contacts.
  • the potential around each point is closer to the ground potential (desirable for creating strong cross fields) the thinner the dielectric layer 54 is.
  • the roller 52 thus operates more or less the same as the roller 12 with regard to the detection of a pattern of electrical charge areas with microscopic periodic variation, but macroscopic image dependency.
  • the charge areas thus produce non-uniform image-dependent electric fields that can and may extend from the roller surface 52a polarize a development medium and pull it onto this surface.
  • the write head 72 with its "scratched" contacts 74 can be produced using the methods of conventional printed circuit board technology.
  • the in FIG. 5 includes a substrate 76 made of an insulating material such as ceramic or glass, which extends over the full width of the printing roller 52.
  • a selectively etchable insulating layer 78 made of silicon dioxide or the like is deposited on the substrate.
  • a conductive metal layer 82 is deposited above this layer. The deposited metal can be patterned (i.e., etched after photoresist is applied) so that a contact 74 is present approximately every 50 ⁇ m with suitable width / spacing dimensions. The distance can be, for example, one half of the metal width or can be chosen as desired.
  • terminal pads 74a can be used to connect the contacts to the pressure source, i.e. a wire charging component can be provided. These paths can be shifted from one another, as shown, to provide enough space for wire bonding or to provide contact areas for a removable contact assembly (not shown).
  • the layer 78 of insulating material at the bottom of the substrate 76 next to the contact working ends can be etched away so that the contact ends are free of the substrate and "float” as schematically shown in FIG. 4 shown.
  • the conductive layer 82 can be formed as a bimetal layer, so that when detached the metal bends like a bimetal spring, so that the contacts 74 are in good elastic sliding contact with the roller surface 52 a.
  • the ends of the contacts 74 can be made thicker for better wear resistance. You can also use these ends split to form a brush for better elasticity and better contact with the conductive dots on the platen.
  • Each voltage feed point 74 can also be formed in the form of a plurality of smallest electrical fingers, as shown in FIG. 4a.
  • the points 56 are embedded in the dielectric layer 54.
  • the electrical fingers of a single feed point 74 are all charged to an equal (similar) voltage, but have a very high resistivity in a direction parallel to a line immediately across the width of the recording surface.
  • the control device for the write head can be set to the voltage of each feed point individually, as described above. Due to manufacturing tolerances, contact 74 may often touch not only the point but also part of the dielectric, as shown in FIG. 4a. But due to the larger difference and the lack of a conductive point that facilitates the feeding of the electrical charge, the charge on the dielectric on the surface is minimal. Thus, when voltage contact 74 moves away from the point, micro-fields arise between point 56, which remains charged, and the dielectric surface, which remains largely uncharged.
  • FIG. 4 points shown contact the ground plane via resistors or ohmic connectors with a smaller specific resistance than that of the dielectric.
  • the point remains charged for a certain time, even if its discharge rate is higher than if there were no resistors.
  • the optimal specific resistance between the point and the ground plane depends on various factors, including the speed of the printing roller, tension limits, desired ink strength and others.
  • the specific resistance can also be via the Composition, depth and size of the points can be influenced.
  • the dots When contacting with metal wires, the dots are preferably made from a hard metal connection, e.g. TiN, ZrN or zirconium oxide.
  • FIG. 4b shows, by way of illustration, microfields MF located on the surface 52a between the points and the substantially uncharged dielectric material as the points 56 move away from the contacts 74.
  • the microfields MF then attract ink from the application station as described above.
  • FIG. 6 illustrates another embodiment of a pressure roller, generally designated 92, but having a slightly different anisotropic dielectric layer 94 on the conductive layer 38.
  • the layer 94 also bears a pattern of conductive points 96.
  • the points 96 are alternately connected to the ground plane 36 by conductive paths 98.
  • the conductive paths 98 can be formed by "pinholes" filled with conductive material, by plated paths, or even by minute wires.
  • conductive paths 98 may be made of a semiconductor material, e.g. Polysilicon, so that there is a relatively high resistance. In this way, somewhat higher transverse electric fields are achieved over the recording surface 92 of the roller 92 when the roller is written with the write head 72.
  • FIG. 3 Another embodiment shown eliminates the need for a ground plane in the pressure roller because unearthed adjacent points of the dot pattern are charged in opposite directions.
  • points 56 can be made via the roller odd numbers are positively charged, even numbered dots 56 having a corresponding negative potential using the contact write head 72 as shown in FIGURES 5 and 6. This causes field lines across the space between the two sets of dots so that ink is drawn between the dots.
  • FIG. 7 shows a write head 172 which has a multiplicity of sets S1, S2, S3 etc. of two feed points with a parallel arrangement to the direction of movement of a dielectric recording surface.
  • the recording surface may be a simple dielectric surface, preferably one with dots or areas of higher conductivity on the surface as described above.
  • the write head can be independently set to a voltage difference for each set S1, S2, etc. based on electronic data representing the image to be recorded on a dielectric recording surface.
  • successive lines of the image are written with the write head across the entire width of the recording surface as it traverses the recording surface.
  • the voltage difference preferably varies between zero and a maximum of 30 to 200 volts, so that the ink is attracted variably in accordance with the voltage difference.
  • the grouping can be done as for the write head of FIG. 4 and 5.
  • the voltages V1, V3, V1 can be such that the voltages of the feed points in the sets next to one another are equal. This helps to avoid microfields between two adjacent sets if desired.
  • the recording surface for this embodiment can be a simple dielectric surface, and dots as described above can also be present.
  • dots 156 may be rectangles with the full size of a picture element (pixel), e.g. 50 microns.
  • the varying voltages can be supplied by a DC voltage source.
  • alternating voltage sources can also be used, the voltage amplitude being variable.
  • the layer 136 is an ungrounded conductive layer which receives an approximately constant voltage equal to the mean value of the varying AC voltage when the pressure roller rotates. The varying voltage of the contact points on surface 52a can then be used to charge the dielectric since the voltage on layer 136 remains approximately constant.
  • a printing component with a charged anisotropic surface can interact with a dielectric development medium or any other dielectric material with a dielectric constant greater than one.
  • a dielectric development medium or any other dielectric material with a dielectric constant greater than one We have described the invention here for use in printing equipment with a dispensing station that dispenses thermoplastic inks, but the printing components described can also be used to hold solid, uncharged dielectric dyes and uncharged toners.
  • the term "printing ink” is therefore intended to generally refer to a dielectric development medium in which the dielectric constant is greater than one, and is not restricted to liquid printing inks.
  • charged ones can also be used in connection with the embodiments described above, but the resulting desired attraction of the color and the thicknesses must then be modified taking into account the stronger attraction.
  • the write head can also comprise a plasma charging component and charge via individual plasma introduction points, similar to the microtunnel plasma device described above.
  • the print head can also have a gas charging device and charge the points via the gas delivery points.
  • the contact wires of the embodiment shown in FIG. 4 can, for example, be designed such that there is no real contact with the recording surface, but rather the charges are conveyed via the air.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Dot-Matrix Printers And Others (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
EP95117918A 1994-11-18 1995-11-14 Dispositif d'impression Expired - Lifetime EP0713155B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US34213594A 1994-11-18 1994-11-18
US342135 1994-11-18
US08/469,323 US6031552A (en) 1994-11-18 1995-06-06 Printing device with patterned recording surface
US469323 1999-12-22

Publications (3)

Publication Number Publication Date
EP0713155A2 true EP0713155A2 (fr) 1996-05-22
EP0713155A3 EP0713155A3 (fr) 1997-06-04
EP0713155B1 EP0713155B1 (fr) 2002-08-14

Family

ID=26992842

Family Applications (1)

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EP95117918A Expired - Lifetime EP0713155B1 (fr) 1994-11-18 1995-11-14 Dispositif d'impression

Country Status (6)

Country Link
US (1) US6031552A (fr)
EP (1) EP0713155B1 (fr)
JP (1) JPH08262924A (fr)
CN (1) CN1059392C (fr)
AT (1) ATE222380T1 (fr)
DE (1) DE59510320D1 (fr)

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DE10030162A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines elektrostatischen Musters auf einen Bildzylinder
DE10030180A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Verfahren zur Herstellung eines Bildzylinders und Vorrichtung zum Aufzeichnen eines elektrostatischen Musters
DE10030164A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines Elektrostatischen Musters und Verfahren zum Reinigen eines Elektrografischen Schreibkopfes
DE10030171A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines elektrostatischen Musters auf einen Bildträger und Verfahren zum Betreiben der Aufzeichnungsvorrichtung
DE10030166A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Verfahren zum Reinigen eines elektrografischen Schreibkopfes und Vorrichtung zum Erzeugen eines elektrostatischen Musters
DE10030182A1 (de) * 2000-06-20 2002-03-14 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines elektrostatischen Musters auf einen Bildzylinder

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AU2003248305B2 (en) * 1998-12-16 2005-05-26 Zamtec Limited A printer for incorporation into consumer electronic (CE) systems with limited access
SG116487A1 (en) * 1998-12-16 2005-11-28 Silverbrook Res Pty Ltd Duplex inkjet printing system.
US6631986B2 (en) * 1998-12-16 2003-10-14 Silverbrook Research Pty Ltd Printer transport roller with internal drive motor
EP1229392A3 (fr) * 2001-01-31 2006-08-02 Seiko Epson Corporation Support d'image, méthode de sa fabrication et dispositif de formation d'images avec celui-ci
US20080100534A1 (en) * 2006-10-26 2008-05-01 Hewlett-Packard Development Company Lp Switch

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US5315061A (en) 1989-10-13 1994-05-24 Ricoh Company, Ltd. Developing apparatus using a developer carrier capable of forming microfields
US5325120A (en) 1991-11-15 1994-06-28 Kuehnle Manfred R Electrostatic reproduction apparatus having a dielectric ink-phobic imaging member and field-emission write head

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US3739748A (en) 1970-12-15 1973-06-19 Xerox Corp Donor for touchdown development
US4792860A (en) 1987-02-27 1988-12-20 Kuehrle Manfred R Thermodynamic printing method and means
US5315061A (en) 1989-10-13 1994-05-24 Ricoh Company, Ltd. Developing apparatus using a developer carrier capable of forming microfields
US5325120A (en) 1991-11-15 1994-06-28 Kuehnle Manfred R Electrostatic reproduction apparatus having a dielectric ink-phobic imaging member and field-emission write head

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10030162A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines elektrostatischen Musters auf einen Bildzylinder
DE10030180A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Verfahren zur Herstellung eines Bildzylinders und Vorrichtung zum Aufzeichnen eines elektrostatischen Musters
DE10030164A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines Elektrostatischen Musters und Verfahren zum Reinigen eines Elektrografischen Schreibkopfes
DE10030171A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines elektrostatischen Musters auf einen Bildträger und Verfahren zum Betreiben der Aufzeichnungsvorrichtung
DE10030166A1 (de) * 2000-06-20 2002-01-03 Heidelberger Druckmasch Ag Verfahren zum Reinigen eines elektrografischen Schreibkopfes und Vorrichtung zum Erzeugen eines elektrostatischen Musters
DE10030182A1 (de) * 2000-06-20 2002-03-14 Heidelberger Druckmasch Ag Vorrichtung zum Aufzeichnen eines elektrostatischen Musters auf einen Bildzylinder

Also Published As

Publication number Publication date
EP0713155A3 (fr) 1997-06-04
ATE222380T1 (de) 2002-08-15
DE59510320D1 (de) 2002-09-19
EP0713155B1 (fr) 2002-08-14
CN1059392C (zh) 2000-12-13
US6031552A (en) 2000-02-29
JPH08262924A (ja) 1996-10-11
CN1131096A (zh) 1996-09-18

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