EP0780740B1 - Vorrichtung zum direkten elektrostatischen Drucken mit einer Druckkopfstruktur mit Schlitzöffnungen - Google Patents

Vorrichtung zum direkten elektrostatischen Drucken mit einer Druckkopfstruktur mit Schlitzöffnungen Download PDF

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Publication number
EP0780740B1
EP0780740B1 EP19950203534 EP95203534A EP0780740B1 EP 0780740 B1 EP0780740 B1 EP 0780740B1 EP 19950203534 EP19950203534 EP 19950203534 EP 95203534 A EP95203534 A EP 95203534A EP 0780740 B1 EP0780740 B1 EP 0780740B1
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EP
European Patent Office
Prior art keywords
printhead structure
toner
control electrodes
slit
dep
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EP19950203534
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English (en)
French (fr)
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EP0780740A1 (de
Inventor
Guido Desie
Frans Backeljauw
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Agfa Gevaert NV
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Agfa Gevaert NV
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Publication date
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Priority to EP19950203534 priority Critical patent/EP0780740B1/de
Priority to DE1995622948 priority patent/DE69522948T2/de
Priority to US08/768,302 priority patent/US6109729A/en
Priority to JP35375296A priority patent/JP3237818B2/ja
Publication of EP0780740A1 publication Critical patent/EP0780740A1/de
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Classifications

    • 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
    • B41J2/41—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 for electrostatic printing
    • B41J2/415—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 for electrostatic printing by passing charged particles through a hole or a slit
    • B41J2/4155—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 for electrostatic printing by passing charged particles through a hole or a slit for direct electrostatic printing [DEP]
    • 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
    • G03G15/34—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 powder image is formed directly on the recording material, e.g. by using a liquid toner
    • G03G15/344—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 powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array
    • G03G15/346—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 powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array by modulating the powder through holes or a slit
    • 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
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/06—Ink jet characterised by the jet generation process generating single droplets or particles on demand by electric or magnetic field
    • B41J2002/061—Ejection by electric field of ink or of toner particles contained in ink
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2217/00—Details of electrographic processes using patterns other than charge patterns
    • G03G2217/0008—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member
    • G03G2217/0025—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member where the toner starts moving from behind the electrode array, e.g. a mask of holes

Definitions

  • This invention relates to an apparatus used in the process of electrostatic printing and more particularly in Direct Electrostatic Printing (DEP).
  • DEP Direct Electrostatic Printing
  • electrostatic printing is performed directly from a toner delivery means on a receiving member substrate by means of an electronically addressable printhead structure.
  • the toner or developing material is deposited directly in an imagewise way on a receiving substrate, the latter not bearing any imagewise latent electrostatic image.
  • the substrate can be an intermediate endless flexible belt (e.g. aluminium, polyimide etc.).
  • the imagewise deposited toner must be transferred onto another final substrate.
  • the toner is deposited directly on the final receiving substrate, thus offering a possibility to create directly the image on the final receiving substrate, e.g. plain paper, transparency, etc.
  • This deposition step is followed by a final fusing step.
  • the method makes the method different from classical electrography, in which a latent electrostatic image on a charge retentive surface is developed by a suitable material to make the latent image visible. Further on, either the powder image is fused directly to said charge retentive surface, which then results in a direct electrographic print, or the powder image is subsequently transferred to the final substrate and then fused to that medium. The latter process results in an indirect electrographic print.
  • the final substrate may be a transparent medium, opaque polymeric film, paper, etc.
  • DEP is also markedly different from electrophotography in which an additional step and additional member is introduced to create the latent electrostatic image. More specifically, a photoconductor is used and a charging/exposure cycle is necessary.
  • a DEP device is disclosed in e.g. US 3,689,935.
  • This document discloses an electrostatic line printer having a multi-layered particle modulator or printhead structure comprising :
  • Selected potentials are applied to each of the control electrodes while a fixed potential is applied to the shield electrode.
  • An overall applied propulsion field between a toner delivery means and a receiving member support projects charged toner particles through a row of apertures of the printhead structure.
  • the intensity of the particle stream is modulated according to the pattern of potentials applied to the control electrodes.
  • the modulated stream of charged particles impinges upon a receiving member substrate, interposed in the modulated particle stream.
  • the receiving member substrate is transported in a direction orthogonal to the printhead structure, to provide a line-by-line scan printing.
  • the shield electrode may face the toner delivery means and the control electrode may face the receiving member substrate.
  • a DC field is applied between the printhead structure and a single back electrode on the receiving member support. This propulsion field is responsible for the attraction of toner to the receiving member substrate that is placed between the printhead structure and the back electrode.
  • a DEP device is well suited to print half-tone images.
  • the densities variations present in a half-tone image can be obtained by modulation of the voltage applied to the individual control electrodes.
  • different rows of apertures are used for obtaining an image with a high degree of density resolution (i.e. for producing an image comprising a high amount of differentiated density levels) and spatial resolution.
  • a printhead structure consisting of a plastic sheet material with an elongate slit as printing aperture and individual control electrodes on both edges of said slit and on both sides of said plastic material.
  • Such a construction of a printhead structure for ion-printing as described in the above indicated article poses however problems for implementing in the technique of DEP, because the toner delivery means in the DEP technique is normally much larger than the ion-generating means in the ion-printing technique.
  • the apparatus described above do solve, to higher or lower extent, the problem of providing charged toner particles in an imagewise controlled way to an image receptive member without the drawbacks of a complicated printhead structure or complicated guiding structures.
  • DEP Direct Electrostatic Printing
  • An other object of the invention is to provide a DEP device with a printhead structure where clogging of the printing apertures is minimized and where the printing apertures can easily be cleaned.
  • a printhead structure for a DEP (Direct Electrostatic Printing) device comprising, as printing apertures, a slit (103), having two sides, side A (SA) and side B (SB), defined by two edges (A and B) formed by at least one sheet of an insulating material (102), and control electrodes (102a) characterised in that only one of said two sides forming said slit (103) carries control electrodes (102a).
  • DEP Direct Electrostatic Printing
  • DEP device that comprises :
  • a further embodiment provides a DEP device wherein said slit has two sides (SA and SB), defined by two edges (EA and EB), which are formed by at least one sheet of insulating material, said insulating material has an elasticity modulus (Young's Modulus, YM) fulfilling the equation 0.1 GPa ⁇ YM ⁇ 10 Gpa and said edges A and B are mounted with respect to each other at an angle ⁇ fulfilling the equation 0° ⁇ ⁇ ⁇ 45°.
  • said slit is formed by two sheets of insulating material.
  • a common shield electrode (102b) is present on side SB of said slit in addition to said control electrodes (102a) present on side SA of said slit.
  • FIG 1 shows schematically the essential features of a DEP device, wherein a printhead structure according to the present invention can be used.
  • a toner delivery means (101) delivers toner particles in the vicinity of a printhead structure (102) wherein printing apertures (103) are present. Charged toner particles can pass from the toner delivery means to a toner receiving member (104) in a DC field generated by having the toner delivery means at voltage V1 and a back electrode (105) behind said toner receiving member at a voltage V4.
  • the amount of toner passing through aperture (103) is controlled by applying a voltage V3 to a segmented control electrode (102a) around printing aperture (103).
  • a DEP device commonly comprises further (not shown in figure 1), means to move the toner receiving member (104) past the printing apertures (103) and means to fix the toner image to the toner receiving member.
  • FIG. 3 Various printhead structures, being variants on a first embodiment of the present invention, are shown in figure 3.
  • 102 represents the insulating material
  • 102a represents the complex addressable electrode structure, hereinafter called "control electrodes”
  • control electrodes 103 the printing aperture (in this case a slit)
  • arrow TF represents the direction of the toner flow, from the toner delivery means (not shown) to the toner receiving member (not shown).
  • FIG 3a the simplest form of the first embodiment of a printhead structure according to the present invention is shown : on one face of the insulating material (102) forming side A (SA) of the slit (103) control electrodes (102a) are present.
  • SA side A
  • control electrodes (102a) on side A (SA) of the slit face the toner receiving member as can be seen from the direction of arrow TF, representing the direction of the toner flow, from the toner delivery means (not shown) to the toner receiving member (not shown).
  • FIG 3b a variant on the first embodiment of a printhead structure according to the present invention is shown. Again, on one face of the insulating material (102), forming side A (SA) of the slit (103) control electrodes (102a) are present.
  • a continuous electrode (102b), a "shield electrode”, is present on the insulating material (102) forming the side B (SA) of the slit.
  • the control electrodes (102a) on side A (SA) and the control electrode (102b) on side B (SB) of the slit both face the toner receiving member as can be seen from the direction of arrow TF, representing the direction of the toner flow, from the toner delivery means to the toner receiving member (not shown).
  • figure 3c a further variant on the first embodiment of a printhead structure according to the present invention is shown.
  • control electrodes (102a) on side A and a shield electrode (102b) on side B as the variant shown in figure 3b, but now the control electrodes (102a) face the toner receiving member (not shown) and the shield electrode (102b) faces the toner delivery means.
  • the control electrodes (102a) face the toner receiving member (not shown)
  • the shield electrode (102b) faces the toner delivery means.
  • a printhead structure comprising a shield electrode (102b) on both faces of the insulating material forming side B (SB) of the slit (103), and control electrodes (102a) on only one face of the insulating material (102), is still an other variant on the first embodiment of a printhead structure of the present invention and is shown in figure 3d.
  • the control electrodes (102a) face the toner receiving member, it is clear that also a printhead structure, as shown in figure 3d can be mounted upside down, in such a way the control electrodes (102a) face the toner delivery means.
  • a continuous shield electrode can be present on that face of said insulating material (102) forming side A of the slit of the printhead structure oppositie to the face carrying the control electrodes (102a).
  • FIG 4a shows again the simplest form of a printhead structure according to the second embodiment of the invention.
  • control electrodes (102a) are present on both faces of the insulating material (102) forming side A (SA) of the slit (103) on the insulating material (102) forming the side B (SB) of the slit.
  • the control electrodes (102a) on both faces of the insulating material forming side A (SA) are located such as to have pairs of control electrodes (102a) (one on every face) exactly in register in pairs.
  • FIG 4b an other variant on the second embodiment of a printhead structure according to the present invention is shown.
  • Side A (SA) of the printhead structure, shown in figure 4b is the same as the one shown in figure 4a, on the insulating material forming side B (SB), however, a continuous shield electrode (102b) is present, facing the toner receiving member, as can be seen from the direction of arrow TF, representing the direction of the toner flow, from the toner delivery means (not shown) to the toner receiving member (not shown).
  • Figure 4c represents a further variant of a printhead structure according to the second embodiment of the invention, and equals the printhead structure shown in figure 4b, except for the shield electrode (102b), that in this variant faces the toner delivery means.
  • FIG 4d still another variant on a printhead structure according to the second embodiment of this invention is shown.
  • Side A (SA) of the printhead structure, shown in figure 4d is the same as the one shown in figure 4a; on both faces of the insulating material forming side B (SB), however, a continuous shield electrode (102b) is present.
  • control electrodes (102a), being present on both faces of the insulating material (102) forming side A (SA) of the slit (103) can, in pairs, be connected to each other via metallisation through said aperture (107), forming a single control electrode.
  • Ways and means for connecting electrodes trough printing apertures are known in the art. Examples of such means have been disclosed in EP-A 753 413
  • FIG 5a a variant of a third embodiment of a printhead structure according to the present invention is shown.
  • the control electrodes (102a) on both faces of the insulating material forming side A (SA) are staggered.
  • the width of the control electrodes parallel to the length of the slit (103) is selected such as to have some overlap between the control electrodes on one face of the insulating material (102) and the other.
  • the width of the control electrodes parallel to the length of the slit (103) is selected such as to have no overlap between the control electrodes on one face of the insulating material (102) and the other.
  • printhead structures are shown, with no electrode on the insulating material forming side B (SB) of the printhead structure.
  • SB side B
  • printhead structures having a side A can also be used in combination with a side B carrying shield electrode (facing the toner delivery means or facing the toner receiving member) on one face of the insulating material, or with a side B carrying a shield electrode on both faces of the insulating material.
  • SA side A
  • the use of printhead structure having a slit as printing apertures and the control electrodes on both faces of the insulating material forming side A (SA) staggered is beneficial for introducing in a DEP device for achieving high resolution prints.
  • the invention is not restricted to printhead structures wherein side A of the slit is formed by a single film of insulating material whereon on both faces control electrodes are present. It is possible to produce a side A of the slit by superposing several sheets of insulating material and have control electrodes on each interface. In this embodiment the multiple control electrode may be staggered, which clearly enhances the resolution achievable with the printhead structure.
  • a printhead structure comprises a slit as printing aperture and that only on one side of the slit control electrodes are present. This bring the advantage that, during the mounting of the printhead structure in the DEP device, no particular demands are raised regarding the registering of the insulating materials forming the sides of the slit.
  • the insulating material, used for producing printhead structure, according to the present invention can be glass, ceramic, plastic, etc.
  • said insulating material is a plastic material, and can be a polyimide, a polyester (e.g. polyethylelene terphthalate, polyethylene naphthalate, etc), polyolefines, an epoxy resin, an organosilicon resin, rubber, etc.
  • Insulating material useful in the present invention, has a elasticity modulus between 0.1 and 10 Gpa, both limits included, preferably between 2 and 8 GPa and most preferably between 4 and 6 GPa.
  • the insulating material has a thickness between 25 and 1000 ⁇ m, preferably between 50 and 200 ⁇ m.
  • the slit in a printhead structure according to the present invention can be from 50 to 500 ⁇ m wide.
  • the width can be chosen as dictated by the resolution needed in the final print.
  • a printhead structure according to any embodiment of the present invention can be mounted in a DEP device in several ways.
  • a printhead structure, according to the present invention and carrying only on one side control electrodes is used, in a DEP device wherein
  • a toner delivery means (101) is located in a toner container, that is formed by a single sheet of plastic material (102) mounted in a rigid frame (106). Slit (103) is formed by the ends (EA) and (EB) of said single sheet of plastic material (102).
  • SA carries control electrodes (102a) on one face, facing the toner delivery means (101), side B (SB) carries no electrodes.
  • the printhead structure (102) comprises a slit aperture (103).
  • the side A (SA) of the slit defined by edge A (EA), carries control electrodes (102a).
  • SA and SAB are, in this specific embodiment of the invention, two separate sheets of plastic mounted a rigid frame (106), having a free non supported length (FL). The two sheets are mounted such that angle ⁇ fulfils the equation 0° ⁇ ⁇ ⁇ 45°.
  • toner particles are attracted to toner the receiving member (104), by a DC field generated by having the toner delivery means at voltage V1 and a back electrode (105) behind said toner receiving member at a voltage V4.
  • the amount of toner passing trough the printing apertures (103) is controlled by applying a voltage V3 to a segmented control electrode (102a).
  • Said control electrodes face, in the shown embodiment, the toner delivering means in said DEP device.
  • Side B (SB) of the printhead structure (102) does not carry any electrode.
  • the two sheets of plastic material in the printhead structure are bent towards the toner delivery means (101) and contact it so that a controlled pressure is exerted upon said toner delivery means.
  • Said pressure is well controlled by proper adjustment of the angle of both of said sheets of plastic material towards the frame, and by selecting a plastic material with a suitable elasticity modulus (Youngs modulus) and thickness.
  • the slit in the printhead structure is realized by mounting two separate sheets of insulating material to form side A (SA) and side B (SB) of the slit, it is preferred that sheet A and B are made of the same material.
  • the insulating material used for forming side A (SA) can be different from the insulating material used for forming side B (SB), as long as both insulating materials fulfil the requirements on the elasticity (Young's modulus) as described hereinbefore. Both insulating materials can have the same or a different thickness.
  • the form, material and the position of the rigid frame (106) is immaterial for the present invention.
  • the frame (106) can be located as needed, as long as the value of angle ⁇ fulfils the equation 0° ⁇ ⁇ 45°.
  • the angle ⁇ is greater than or equal to 0° and lower than 45°. In a preferred embodiment said angle varies from 0° to 25° and in a most preferred embodiment said angle varies between 0° and 10° degrees.
  • a printhead structure according to the present invention is preferably mounted in the DEP device so that the insulating material forming the printhead structure contacts the surface of the toner delivery means, as illustrated in figures 6 and 7. It is however possible to mount a printhead structure according to the present invention in a DEP device so that no contact between the insulating material forming the printhead structure and the surface of the toner delivery means is present.
  • the toner delivery means (101) used in DEP devices using a printhead structure according to the present invention may be a CTC (charged toner conveyer) bringing toner particles in the vicinity of the slit (printing aperture) (103) and said toner particles can be brought to the CTC by a magnetic brush. It is also possible to use a printhead structure according to the present invention in a DEP device wherein the toner particles are directly extracted from a magnetic brush (the magnetic brush being then the toner delivery means). A DEP device wherein the toner particles are directly extracted from a magnetic brush has been disclosed in EP-A 675 417, that is incorporated herein by reference.
  • the back electrode (105) of this DEP device can also be made to cooperate with the printhead structure, said back electrode being constructed from different styli or wires that are galvanically isolated and connected to a voltage source as disclosed in e.g. US 4,568,955 and US 4,733,256.
  • the back electrode, cooperating with the printhead structure can also comprise one or more flexible PCB's (Printed Circuit Board).
  • V3 is selected, according to the modulation of the image forming signals, between the values V3 0 and V3 n , on a time basis or grey-level basis.
  • Voltage V4 is applied to the back electrode (105) behind the toner receiving member (104).
  • Voltage V2 is applied to the shield electrode.
  • not only V3 is varied between V3 0 and V3 n , also multiple voltages V2 0 to V2 n and/or V4 0 to V4 n can be used.
  • voltage V5 is applied to the surface of the sleeve of the magnetic-brush.
  • no shield electrode is present, there is no voltage V2.
  • a DEP device can be operated successfully when a single magnetic brush is used in contact with the CTC to provide a layer of charged toner on said CTC.
  • the device can also be operated when the toner particles are directly extracted from a magnetic brush.
  • an additional AC-source can be connected to the sleeve of the magnetic brush when the magnetic brush is used to bring the toner particles on a CTC as well as when the toner particles are directly extracted from a magnetic brush.
  • the magnetic brush preferentially used in a DEP device according to the present invention when the magnetic brush is used to bring the toner particles on a CTC as well as when the toner particles are directly extracted from a magnetic brush, is of the type with stationary core and rotating sleeve.
  • any type of known carrier particles and toner particles can successfully be used. It is however preferred to use "soft" magnetic carrier particles.
  • Soft magnetic carrier particles useful in a DEP device according to a preferred embodiment of the present invention are soft ferrite carrier particles. Such soft ferrite particles exhibit only a small amount of remanent behaviour, characterised in coercivity values ranging from about 50 up to 250 Oe.
  • Further very useful soft magnetic carrier particles for use in a DEP device according to a preferred embodiment of the present invention, are composite carrier particles, comprising a resin binder and a mixture of two magnetites having a different particle size as described in EP-B 289 663.
  • the particle size of both magnetites will vary between 0.05 and 3 ⁇ m.
  • the carrier particles have preferably an average volume diameter (d v50 ) between 10 and 300 ⁇ m, preferably between 20 and 100 ⁇ m. More detailed descriptions of carrier particles, as mentioned above, can be found EP 675 417, that is incorporated herein by reference.
  • toner particles with an absolute average charge corresponding to 1 fC ⁇
  • the absolute average charge of the toner particles is measured by an apparatus sold by Dr. R. Epping PES-Laboratorium D-8056 Neufahrn, Germany under the name "q-meter”. The q-meter is used to measure the distribution of the toner particle charge (q in fC) with respect to a measured toner diameter (d in 10 ⁇ m). From the absolute average charge per 10 ⁇ m (
  • the charge distribution measured with the apparatus cited above, is narrow, i.e. shows a distribution wherein the coefficient of variability (v), i.e. the ratio of the standard deviation to the average value, is equal to or lower than 0.33.
  • the toner particles used in a device according to the present invention have an average volume diameter (d v50 ) between 1 and 20 ⁇ m, more preferably between 3 and 15 ⁇ m. More detailed descriptions of toner particles, as mentioned above, can be found in EP 675 417, that is incorporated herein by reference.
  • a DEP device including a printhead structure according to the present invention can function by using single component magnetic toners, with two component developers where the toner particles are charged by triboelectric contact with carrier particles and also with non magnetic mono component development systems.
  • the insulating material, forming the printhead structure such as to have specific tribo electric properties, or to coat said insulating material to give it specific tribo electric properties.
  • toner particles on a rotating toner supply roller can be in rotating contact with said insulating material, forming the printhead structure, and be charged by that contact.
  • a DEP device making use of the above mentioned marking toner particles can be addressed in a way that enables it to give black and white. It can thus be operated in a "binary way", useful for black and white text and graphics and useful for classical bilevel halftoning to render continuous tone images.
  • a DEP device is especially suited for rendering an image with a plurality of grey levels.
  • Grey level printing can be controlled by either an amplitude modulation of the voltage V3 applied on the control electrode 102a or by a time modulation of V3. By changing the duty cycle of the time modulation at a specific frequency, it is possible to print accurately fine differences in grey levels. It is also possible to control the grey level printing by a combination of an amplitude modulation and a time modulation of the voltage V3, applied on the control electrode.
  • the carrier particles are of the carrier particles.
  • a macroscopic "soft" ferrite carrier consisting of a MgZn-ferrite with average particle size 50 ⁇ m, a magnetisation at saturation of 29 emu/g was provided with a 1 ⁇ m thick acrylic coating. The material showed virtually no remanence.
  • the toner used for the experiment had the following composition : 97 parts of a co-polyester resin of fumaric acid and bispropoxylated bisphenol A, having an acid value of 18 and volume resistivity of 5.1 x 10 16 ohm.cm was melt-blended for 30 minutes at 110° C in a laboratory kneader with 3 parts of Cu-phthalocyanine pigment (Colour Index PB 15:3).
  • a resistivity decreasing substance having the following formula : (CH 3 ) 3 N + C 16 H 33 Br - was added in a quantity of 0.5 % with respect to the binder, as described in WO 94/027192. It was found that - by mixing with 5 % of said ammonium salt - the volume resistivity of the applied binder resin was lowered to 5 ⁇ 10 14 Q.cm. This proves a high resistivity decreasing capacity (reduction factor : 100).
  • the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
  • the average particle size was measured by Coulter Counter model Multisizer (tradename), was found to be 6.3 ⁇ m by number and 8.2 ⁇ m by volume.
  • the toner particles were mixed with 0.5 % of hydrophobic colloidal silica particles (BET-value 130 m 2 /g).
  • An electrostatographic developer was prepared by mixing said mixture of toner particles and colloidal silica in a 4 % ratio (w/w) with carrier particles.
  • the triboelectric charging of the toner-carrier mixture was performed by mixing said mixture in a standard tumbling set-up for 10 min.
  • the developer mixture was run in the magnetic brush for 5 minutes, after which the toner was sampled and the tribo-electric properties were measured, according to a method as described in the above mentioned European application 94201026.5, filed on April 14, 1994.
  • the average charge, q, of the toner particles was -7.1 fC.
  • the toner delivery means The toner delivery means
  • the toner delivery means comprised a cylindrical charged toner conveyer with a sleeve made of aluminium with a TEFLON (trade name) coating an a surface roughness of 2.5 ⁇ m (Ra-value measured according to ANSI/ASME B46.1-1985) and a diameter of 20 mm.
  • the charged toner conveyer was rotated at a speed of 50 rpm.
  • the charged toner conveyer was connected to an AC power supply with a square wave oscillating field of 600 V at a frequency of 3.0 kHz with 20 V DC-offset.
  • toner was propelled to this conveyer from a stationary core/rotating sleeve type magnetic brush comprising two mixing rods and one metering roller. One rod was used to transport the developer through the unit, the other one to mix toner with developer.
  • the magnetic brush was constituted of the so called magnetic roller, which in this case contained inside the roller assembly a stationary magnetic core, having three magnetic poles with an open position (no magnetic poles present) to enable used developer to fall off from the magnetic roller (open position was one quarter of the perimeter and located at the position opposite to said CTC.
  • a scraper blade was used to force developer to leave the magnetic roller.
  • a doctoring blade was used to meter a small amount of developer onto the surface of said magnetic brush.
  • the sleeve was rotating at 100 rpm, the internal elements rotating at such a speed as to conform to a good internal transport within the development unit.
  • the magnetic brush was connected to a DC power supply of - 200V.
  • a first sheet (sheet A) of plastic material 50 ⁇ m thick polyimide
  • sheet A plastic material
  • sheet B plastic material
  • the first one of said plastic sheets with the control electrodes and double polyimide layers was placed at a position so that the surface of the charged toner conveyor was rotating from said first sheet of plastic with double layer of polyimide and copper electrodes, over said printing aperture slit, towards said polyimide sheet of 50 ⁇ m thickness with a continuous copper layer.
  • Each of said control electrodes was individually addressable from a high voltage power supply.
  • the printhead structure that consists of two separate plastic sheets is touching the sleeve of the charged toner conveyer.
  • the distance between the back electrode and the back side of the printhead structure was set to 150 ⁇ m and the paper travelled at 1 cm/sec.
  • To the individual control electrodes an (imagewise) voltage V3 between 0 V and -300 V was applied.
  • the back electrode 105 was connected to a high voltage power supply of +600 V.
  • To the sleeve of the CTC an AC voltage of 600 V at 3.0 kHz was applied, with 20 V DC offset.
  • Example 1 was repeated, except that for the second sheet (sheet B) of plastic material a polyimide film of 50 ⁇ m thickness without any continuous copper layer was used. All other parameters were equivalent to the ones mentioned in example 1.
  • Example 1 was repeated, except that for the second sheet (sheet B) of plastic material a polyimide film of 50 ⁇ m thickness with continuous copper layer of 8 ⁇ m thickness was used. The copper side of said second sheet of plastic material was facing the back electrode. All other parameters were equivalent to the ones mentioned in example 1.
  • Example 1 was repeated, except that for the second sheet (sheet B) of plastic material a polyimide film of 50 ⁇ m thickness with continuous copper layer of 8 ⁇ m thickness on both sides was used. All other parameters were equivalent to the ones mentioned in example 1.
  • Example 1 was repeated, except for the structure of the first sheet (sheet A) of plastic material comprising control electrodes, said sheet of plastic material of 125 ⁇ m thickness having 8 ⁇ m thick copper control electrodes facing the back electrode.
  • the angle of both of said sheets of plastic material towards said plastic frame was set to 10° and FL was 50 mm.
  • Example 2 was repeated, except for the structure of the first sheet (sheet A) of plastic material comprising control electrodes, said sheet of plastic material of 125 ⁇ m thickness having 8 ⁇ m thick copper control electrodes facing the back electrode.
  • the angle of both of said sheets of plastic,material towards said plastic frame was set to 10° and FL was 50 mm.
  • Example 3 was repeated, except for the structure of the first sheet (sheet A) of plastic material comprising control electrodes, said sheet of plastic material of 125 ⁇ m thickness having 8 ⁇ m thick copper control electrodes facing the back electrode.
  • the angle of both of said sheets of plastic material towards said plastic frame was set to 10° and FL was 50 mm.
  • Example 4 was repeated, except for the structure of the first sheet (sheet A) of plastic material comprising control electrodes, said sheet of plastic material of 125 ⁇ m thickness having 8 ⁇ m thick copper control electrodes facing the back electrode.
  • the angle of both of said sheets of plastic material towards said plastic frame was set to 10° and FL was 50 mm.
  • Example 5 was repeated except for the fact that the control electrodes faced the toner delivery means.
  • Example 6 was repeated except for the fact that the control electrodes faced the toner delivery means.
  • Example 7 was repeated except for the fact that the control electrodes faced the toner delivery means.
  • Example 8 was repeated except for the fact that the control electrodes faced the toner delivery means.
  • a printhead structure was made with control electrodes on both sides of sheet A of the printhead structure.
  • Sheet A of plastic material was 125 ⁇ m thick and had 8 ⁇ m thick copper control electrodes on both sides.
  • Sheet B of the printhead structure was a polyimide layer of 50 ⁇ m thickness and comprised a continuous copper layer of 8 ⁇ m thickness (a shield electrode) facing the toner delivery means.
  • the other parameters were equal to those used in example 5.
  • Example 13 was repeated, except that for the second sheet (sheet B) of plastic material a polyimide film of 50 ⁇ m thickness without any continuous copper layer was used.
  • Example 13 was repeated, except that for the second sheet (sheet B) of plastic material a polyimide film of 50 ⁇ m thickness with continuous copper layer of 8 ⁇ m thickness was used. The copper side of said second sheet of plastic material was facing the back electrode.
  • Example 13 was repeated, except that for the second sheet (sheet B) of plastic material a polyimide film of 50 ⁇ m thickness with continuous copper layer of 8 ⁇ m thickness on both sides was used.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)

Claims (13)

  1. Eine Druckkopfkonstruktion für eine DEP-Einrichtung (DEP = Direct Electrostatic Printing, elektrostatischer Direktdruck), die als Drucköffnungen einen Schlitz (103) mit zwei Seiten, nämlich Seite A (SA) und Seite B (SB), die durch zwei Kanten (A und B) begrenzt sind, die durch mindestens einen Bogen aus isolierendem Material (102) ausgebildet sind, und Steuerelektroden (102a) enthält, dadurch gekennzeichnet, daß nur eine der zwei den Schlitz (103) bildenden Seiten mit Steuerelektroden (102a) versehen ist.
  2. Eine Druckkopfkonstruktion nach Anspruch 1, dadurch gekennzeichnet, daß die Steuerelektroden (102a) auf beiden Kanten der nur einen, Steuerelektroden tragenden Seite vorliegen.
  3. Eine Druckkopfkonstruktion nach Anspruch 2, dadurch gekennzeichnet, daß die Steuerelektroden (102a) auf den beiden Kanten so positioniert sind, daß präzise registerhaltige Paare von Steuerelektroden (102a) erhalten werden.
  4. Eine Druckkopfkonstruktion nach Anspruch 3, dadurch gekennzeichnet, daß die Paare von Steuerelektroden (102a) auf den beiden Kanten paargemäß durch Metallisierung durch Schlitz (103) verbunden sind.
  5. Eine Druckkopfkonstruktion nach Anspruch 2, dadurch gekennzeichnet, daß die Steuerelektroden (102a) auf den beiden Kanten versetzt angeordnet sind.
  6. Eine Druckkopfkonstruktion nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß auf einer der zwei Seiten, nämlich der Seite, die der die Steuerelektroden tragenden Seite zugewandt ist, eine Schirmelektrode (102b) angeordnet ist.
  7. Eine DEP-Einrichtung, die eine Gegenelektrode (105), ein Tonerzuliefermittel (101) und eine Druckkopfkonstruktion (102) nach einem der Ansprüche 1 bis 6 umfaßt.
  8. Eine DEP-Einrichtung nach Anspruch 7, in der :
    (i) der Schlitz zwei Seiten aufweist, Seite A (SA) und Seite B (SB), die durch zwei Kanten (A und B) begrenzt sind, die durch mindestens einen Bogen aus isolierendem Material ausgebildet sind,
    (ii) das isolierende Material einen Elastizitätsmodul (Youngschen Modul, YM) entsprechend Gleichung 0,1 GPa ≤ YM ≤ 10 GPa aufweist, und
    (iii) die Kanten A und B in einem Winkel α entsprechend der Gleichung 0° ≤ α < 45° zueinander angeordnet sind.
  9. Eine DEP-Einrichtung nach Anspruch 8, dadurch gekennzeichnet, daß der Elastizitätsmodul die Gleichung 2 GPa ≤ YM ≤ 8 GPa befriedigt.
  10. Eine DEP-Einrichtung nach einem der Ansprüche 7 bis 9, dadurch gekennzeichnet, daß der Winkel α die Gleichung 0. ≤ α < 20° befriedigt.
  11. Eine DEP-Einrichtung nach einem der Ansprüche 7 bis 10, dadurch gekennzeichnet, daß das isolierende Material eine Stärke zwischen 50 und 200 µm einschließlich beider Grenzen aufweist.
  12. Eine DEP-Einrichtung nach einem der Ansprüche 8 bis 11, dadurch gekennzeichnet, daß der Schlitz durch Anordnen zweier separater Bogen aus isolierendem Material zur Bildung von Seite A (SA) und Seite B (SB) des Schlitzes realisiert wird.
  13. Eine DEP-Einrichtung nach einem der Ansprüche 8 bis 12, dadurch gekennzeichnet, daß Seite A und Seite B eine freie nicht-gestützte Länge (FL) größer oder gleich 20 mm aufweisen.
EP19950203534 1995-12-18 1995-12-18 Vorrichtung zum direkten elektrostatischen Drucken mit einer Druckkopfstruktur mit Schlitzöffnungen Expired - Lifetime EP0780740B1 (de)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP19950203534 EP0780740B1 (de) 1995-12-18 1995-12-18 Vorrichtung zum direkten elektrostatischen Drucken mit einer Druckkopfstruktur mit Schlitzöffnungen
DE1995622948 DE69522948T2 (de) 1995-12-18 1995-12-18 Vorrichtung zum direkten elektrostatischen Drucken mit einer Druckkopfstruktur mit Schlitzöffnungen
US08/768,302 US6109729A (en) 1995-12-18 1996-12-17 Direct electrostatic printing device having a printhead structure with control electrodes on one side of a slit aperture
JP35375296A JP3237818B2 (ja) 1995-12-18 1996-12-18 印刷ヘツド構造体及びｄｅｐ装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19950203534 EP0780740B1 (de) 1995-12-18 1995-12-18 Vorrichtung zum direkten elektrostatischen Drucken mit einer Druckkopfstruktur mit Schlitzöffnungen

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EP0780740A1 EP0780740A1 (de) 1997-06-25
EP0780740B1 true EP0780740B1 (de) 2001-09-26

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Publication number Priority date Publication date Assignee Title
EP0895867A3 (de) * 1997-08-07 1999-03-31 Agfa-Gevaert N.V. Direkte elektrostatische Druckvorrichtung mit einer Kantenelektrode und einem Wechselstromfeld auf dem Tonerzufuhrmitteloberflach
JP2990121B2 (ja) 1997-09-04 1999-12-13 新潟日本電気株式会社 静電式インクジェット記録装置
US6309049B1 (en) 1998-02-18 2001-10-30 The Salmon Group Llc Printing apparatus and method for imaging charged toner particles using direct writing methods
EP0963853B1 (de) 1998-06-09 2001-06-06 Agfa-Gevaert N.V. Druckverfahren für eines Gerät zum direkten elektrostatischen Drucken, das eine Druckkopfanordnung erhaltet mit Ablenkelektroden und Mitteln zur elektrischen Steuerung dieser Ablenkelektroden
EP0983858B1 (de) 1998-06-09 2001-06-06 Agfa-Gevaert N.V. Druckverfahren und Steuerung für Druckkopf mit Ablenkelektroden zum direkten elektrostatischen Drucken
EP0963852B1 (de) 1998-06-09 2001-05-16 Agfa-Gevaert N.V. Druckverfahren und Steuerung für Druckkopf mit Ablenkelektroden zum direkten elektrostatischen Drucken
DE69804433D1 (de) * 1998-06-15 2002-05-02 Array Display Ab Vaestra Froel Verfahren und Vorrichtung für direktes elektrostatisches Drucken
EP1090770A1 (de) 1999-10-08 2001-04-11 Agfa-Gevaert N.V. Vorrichtung zum direkten elektrostatischen Drucken mit einer konventionellen Druckkopfstruktur und einer Wechselspannung, die sowohl an die tonertragende Oberfläche als an die Steuerelektroden gekoppelt ist
US20080047628A1 (en) * 2006-05-26 2008-02-28 Z Corporation Apparatus and methods for handling materials in a 3-D printer

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US4491855A (en) * 1981-09-11 1985-01-01 Canon Kabushiki Kaisha Image recording method and apparatus
US4524371A (en) * 1983-04-01 1985-06-18 Xerox Corporation Modulation structure for fluid jet assisted ion projection printing apparatus
US4763141A (en) * 1987-08-03 1988-08-09 Xerox Corporation Printing apparatus with improved ion focus
US5256246A (en) * 1990-03-05 1993-10-26 Brother Kogyo Kabushiki Kaisha Method for manufacturing aperture electrode for controlling toner supply operation

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JP3237818B2 (ja) 2001-12-10
EP0780740A1 (de) 1997-06-25
DE69522948T2 (de) 2002-04-25
JPH09174914A (ja) 1997-07-08
DE69522948D1 (de) 2001-10-31

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