EP0924089A1 - Structure d'une tête d'impression utilisée dans un dispositif d'impression électrostatique directe comprenant des électrodes symétriques à la surface d'impression - Google Patents

Structure d'une tête d'impression utilisée dans un dispositif d'impression électrostatique directe comprenant des électrodes symétriques à la surface d'impression Download PDF

Info

Publication number
EP0924089A1
EP0924089A1 EP98204099A EP98204099A EP0924089A1 EP 0924089 A1 EP0924089 A1 EP 0924089A1 EP 98204099 A EP98204099 A EP 98204099A EP 98204099 A EP98204099 A EP 98204099A EP 0924089 A1 EP0924089 A1 EP 0924089A1
Authority
EP
European Patent Office
Prior art keywords
printing
printhead structure
control electrodes
apertures
row
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.)
Withdrawn
Application number
EP98204099A
Other languages
German (de)
English (en)
Inventor
Guido Desie
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.)
Agfa Gevaert NV
Original Assignee
Agfa Gevaert NV
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Agfa Gevaert NV filed Critical Agfa Gevaert NV
Priority to EP98204099A priority Critical patent/EP0924089A1/fr
Publication of EP0924089A1 publication Critical patent/EP0924089A1/fr
Withdrawn legal-status Critical Current

Links

Images

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]

Definitions

  • This invention relates to an apparatus for use in the process of electrostatic printing and more particularly in Direct Electrostatic Printing (DEP).
  • DEP Direct Electrostatic Printing
  • electrostatic printing on an image receiving substrate is performed by creating a flow of toner particles from a toner bearing surface to the image receiving substrate and image-wise modulating the flow of toner particles by means of an electronically addressable printhead structure.
  • the toner or developing material is deposited directly in an image-wise way on a receiving substrate, the latter not bearing any image-wise latent electrostatic image.
  • the substrate can be an intermediate endless flexible belt (e.g. aluminium, polyimide etc.).
  • the image-wise 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-A-3 689 935 This document discloses an electrostatic line printer having a multi-layered particle modulator or printhead structure comprising :
  • Each control electrode is formed around one aperture and is isolated from each other control electrode.
  • Selected electric 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 support for a toner receiving substrate 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 substrate, interposed in the modulated particle stream.
  • the receiving 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 electrodes may face the receiving substrate.
  • a DC-field is applied between the printhead structure and a single back electrode on the receiving substrate. This propulsion field is responsible for the attraction of toner to the receiving substrate that is placed between the printhead structure and the back electrode.
  • a DEP device i.e. a device for direct electrostatic printing that can print at high speed with low clogging of the control electrodes and with high and constant maximum density and 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 further object of the invention is to provide a DEP device that can be used with a wide variety of types of toner particles, and that can print at high speed with low clogging of the control electrodes, with high maximum density and with a printing quality that is constant over a long period of time.
  • a printhead structure (106) for use in a device for direct electrostatic printing using dry toner particles comprising a sheet of insulating material (106c) having two faces, a row of printing apertures (106d) through said insulating material, a printing nip, with edges, defined around said row and control electrodes (106a) on at least one of said faces, each of said control electrodes having a first electric conductor (C1) around at least one of said printing apertures, characterised in that two further electric conductors (C2 and C3) extending from said first electric conductor towards said edges, are included in each of said control electrodes, a longer one having a length, LC3, larger than 3 mm and a shorter one having a length, LC2, of at most 4 mm and LC2/LC3 ⁇ 0.75.
  • Figure 1 illustrates schematically the definition of a printing nip and its dimensions.
  • Figure 2 shows a printhead structure according to the prior art.
  • Figure 3 shows a printhead structure according to a first embodiment of the present invention.
  • Figure 4 shows a printhead structure according to a second embodiment of the present invention.
  • Figure 5 shows a DEP device comprising a printhead structure of the first embodiment of the present invention.
  • Figure 6 shows a DEP device comprising a printhead structure of a second embodiment of the present invention.
  • DEP direct electrostatic printing
  • a flow of charge toner particles is created between a means for delivering charged toner particles and an image receiving substrate.
  • a printhead structure having control electrodes around printing apertures, is interposed in said flow of toner particles for image-wise controlling said flow of toner particles.
  • the application of an AC-field to the surface of a means for delivering toner particles can be used to increase the printing speed by providing a denser flow of toner particles in the vicinity of the printing apertures.
  • This dense flow of toner particles from the surface bearing charged toner particles to a back electrode is a continuous flow, and this dense flow is image-wise modulated by putting a DC-voltage upon the control electrodes present in said printhead structure.
  • Said DC-voltage either has a further propagating field (leading to image density) or a blocking field (leading to no-image density).
  • a "printing nip” can be defined in the vicinity of each row of printing apertures that are associated with control electrodes.
  • a “printing nip” is shown in figure 1, a “printing nip” occupies a surface in the printhead structure (120) defined by the length, l of the row of printing apertures (106d) and by two distances , a and b, extending, from the line through the centre points of the printing apertures in the row of printing apertures, in opposite directions parallel to the movement, in the direction of arrow D, of the image receiving substrate.
  • Charged toner particles present under the "printing nip” are influenced by the electric field provided by the control electrodes in the "printing nip". Charged toner particles outside the “printing nip” are not influenced by the electric field in said "printing nip” so that they do not have any tendency to move to or from the neighbourhood of said printing apertures.
  • the dimensions of the "printing nip” vary. It is possible that the distances a and b are equal (a symmetrical printing nip) or that these distances are different.
  • the present invention includes a printhead structure in which the "electrical" surfaces that individual toner particles can see, i.e. the electric fields that influence the toner particles, approaching and leaving the vicinity of the row of printing apertures, is equivalent for all printing apertures.
  • the region under the "printing nip" from where the means for delivering toner particles brings charged toner particles to the vicinity of the printing apertures is the "feed-region” and the region under the "printing nip” wherein the non-used toner particles are brought after being passed in the vicinity of the apertures is the "removal-region”. It is very difficult, even impossible to print the same density through a printing aperture associated with a control electrode having a conductor (for connecting said control electrode to a voltage source) extending in the "feed-region” and a printing aperture associated with a control electrode having a conductor (for connecting said control electrode to a voltage source) extending in the "removal-region".
  • the printing apertures (P1) and the control electrode (P2) are accompanied by dummy electrodes (P2) that are only present for adjusting the electric fields in the vicinity of the printing apertures.
  • the construction of such a printhead structure is not that straightforward, and especially when two rows of printing apertures are present in the printhead structure, designing a compact geometry of the rows of printing apertures and dummy electrodes is not so simple.
  • control electrodes do not have a plane of symmetry through the line connecting the centre of the apertures so that it is not guaranteed that the electric fields acting on the charged toner particles in the "feed region” and in the "removal region” are the same.
  • This procedure does diminish the influence of the various control electrode strips extending in between and towards the various rows of printing apertures on the toner particles but also diminishes the printing speed, since, e.g., with a printhead structure having four rows of printing apertures only one row at a time is used for printing while otherwise the four rows are simultaneously used for printing. This means that in this case the printing speed with the method of DE-A-197 16 115 for avoiding the influence of the various electric fields on the toner particles is four times slower.
  • a printhead structure for use in a device for direct electrostatic printing using dry toner particles comprising a sheet of insulating material having two faces, at least one row of printing apertures through said insulating material, a printing nip, with edges parallel to said row of printing apertures, defined around said row and control electrodes on at least one of said faces, each of said control electrodes having a first electric conductor around at least one of said printing apertures, and two further electric conductors connected to said first one and extending towards said edges of said printing nip, one of said further conductors being longer than 3 mm, with length LC3 and one having a length, LC2, of at most 4 mm and wherein LC2/LC3 ⁇ 0.75.
  • the longer one of the further conductors is coupled to a variable voltage source for selectively preventing the charged toner particles from passing the printing apertures and allowing the charged toner particles to pass the printing in accordance with image data to be printinted.
  • a printhead structure according to a first embodiment of the present invention, having a single row of printing apertures is shown. Eight printing apertures (106d) on a single row are shown, each of the printing apertures is surrounded by a first conductor (C1) and two conductors, a shorter one (C2) and a longer one (C3) extending from said first conductor towards the edges of the printing nip (120).
  • said further conductor having a length larger than 3 mm (C3) included in a first control electrode and coupled to a voltage source, and said further conductor having a length larger than 3 mm (C3) included in a control electrode adjacent to said first control electrode and coupled to a voltage source are located on opposite sides of said row of printing apertures.
  • FIG 4 shows a printhead structure according to a second embodiment of the present invention, wherein two parallel rows of eight printing apertures are shown.
  • Each of the printing apertures (106d) of the first row is surrounded by a first conductor (C1) and two conductors, a shorter one (C2) and a longer one (C3) extending from said first conductor towards the edges of the printing nip (120) and each of the printing apertures (106d') of the second row is surrounded by a first conductor (C1') and two conductors a short one (C2') and a long one (C3') extending from said first conductor towards the edges of the printing nip (120').
  • the conductor (C1) of the control electrode around each of the printing apertures is connected to two further conductors, a shorter one (C2) having a length, LC2, of at most 4 mm and a longer one, having a length, LC3, larger than 3 mm (C3) (or groups of conductors) conductor C2 and C3 extending in a direction opposite to each other and towards the edges of the printing nip that are parallel with the row of printing apertures. It was found that with such a printhead structure it was possible to print an equal density through all printing apertures.
  • each of said control electrodes is coupled to a voltage source arranged for image-wise modulating a flow of toner particles through the row of printing apertures. It is further preferred that the conductor, of said two further conductors, connected to the voltage source is longer than the other conductor.
  • Figure 3 and 4 show schematically a printhead structure with control electrodes according to this invention, but are not intended to show, on scale, exact dimensions. E.g. the conductors C3, which in the figure is longer than conductor C2 can extend farther away from the edge of printing nips 120 and 120' for being connected to a voltage source, that is not shown in the figures 3 and 4.
  • the two further conductors (C3 and C2) coupled to the conductor C1 of the control electrode around the printing aperture have an extension that is related to the extension of the printing nip. It is preferred that the longer of the further conductors has a length LC3 such that LC3 ⁇ (a + b)/2, preferably so that LC3 ⁇ a + b and the other one of the shorter one of the two further conductors has a length LC2, such that 0.25 ⁇ (LC2/(a + b)) ⁇ 0.5.
  • LC2 LC2 is chosen such that it varies between 0.5 mm and 4 mm, both limits included and in a very preferred embodiment LC2 is between 1 mm and 4 mm, both limits included.
  • the values of LC3 vary between 0.5 mm and 4 mm or larger, preferably between 1 mm and 8 mm or larger as long as LC2/LC3 ⁇ 0.75.
  • control electrodes designed according to this invention is beneficial in any printhead structure for use in direct electrostatic printing comprising control electrodes and a common shield electrode as well as in a printhead structure where no shield electrode is present.
  • Control electrodes designed as described immediately above can also be incorporated in a printhead with a specific shield electrode.
  • Control electrodes, designed as per this invention can be used in a printhead structure comprising, an insulating material having a first and a second side, said first side carrying control electrodes associated with printing apertures, said second side carrying a shield electrode, wherein
  • a printhead structure, according to this invention, having control electrodes with conductors as described above can be used in any DEP device known in the art, e.g. in devices as described in EP-A-795 802, EP-A-780 740, EP-A-740 224, EP-A-731 394, EP-A-712 055, US-A-5 606 402, US-A-5 523 777, GB-A-2 108 432, US-A-4 743 926 . It can also be used in a method for direct electrostatic printing operating without back electrode, as disclosed in EP-A-823 676 .
  • a printhead structure in the vicinity of the printing apertures can originate from a surface carrying charged mono-component magnetic developer, from a surface carrying charged non-magnetic mono-component toner brought to said surface from a container for non-magnetic mono-component developer as well as brought to said surface from a magnetic brush containing two-component developer with non-magnetic toner particles and magnetic carrier particles.
  • the toner cloud may also originate directly from a magnetic brush containing two-component developer with non-magnetic toner particles and magnetic carrier particles.
  • a printhead structure according to this invention with the described geometry of the control electrodes, in a DEP device wherein the flow of toner particles from the means for delivering toner particles and the image receiving member is controlled by a printhead structure that is arranged for image-wise providing an AC-field between said means for delivering toner particles and said control electrode.
  • a printhead structure that is arranged for image-wise providing an AC-field between said means for delivering toner particles and said control electrode.
  • the toner flow through the printing apertures is basically controlled by image-wise applying an AC-field over the gap between the surface of the means for delivering toner particles and the printhead structure : when an AC-field is present the toner flow passes the printing apertures, when NO AC-field is present the printing aperture is blocked.
  • a device for direct electrostatic printing including a printhead structure of the present invention can comprise a shield electrode, then, the shield electrode (106b) is preferably kept at ground potential (i.e. 0 V, DC). The device can also be operated without shield electrode.
  • the toner bearing surface is kept at a DC-potential - 100 V, whereon an AC-potential with peak to peak voltage 400 V and a frequency 1/ ⁇ 1 is applied.
  • a DC voltage of - 100 V is applied to the control electrode and an AC-potential with peak to peak voltage 400 V and a frequency 1/ ⁇ 1 is applied on top of said DC-potential.
  • the AC voltage on the toner bearing surface and on the control electrode are in phase.
  • the AC-field on the control electrode and the AC-field on the tone bearing surface balance each other out and no AC-field exists over the gap between the toner bearing surface and the control electrodes when the printing aperture has to block the toner flow.
  • a DC voltage of - 0 V is applied to the control electrode, (i.e. the control electrode is grounded).
  • an AC-field exists over the gap between the toner bearing surface and the control electrodes when the printing aperture has to let toner particles pass freely.
  • the DEP device shown comprises means for delivering toner particles with a container (101) for developer (102) wherein a magnetic brush (103) having a core (103a) wherein magnets are present and a sleeve (103b) rotatably mounted around the core is present.
  • the developer (102) can be a mono-component developer with magnetic toner particles and then on the surface of the sleeve of the magnetic brush, toner particles are present, i.e. the surface of the sleeve (103b) of the magnetic brush is the toner bearing surface.
  • the developer (102) can also be a multi-component developer containing magnetic carrier particles and non-magnetic toner particles and then on the sleeve of the magnetic brush carrier and toner particles are present, but the sleeve is still the toner bearing surface in the sense of this invention.
  • the magnetic brush (103) can have a fixed core (103a) and a sleeve (103b) rotatably mounted around the core equipped with means for rotating the core.
  • the core (103a) of the magnetic brush is also equipped with means for rotating the core and can thus also be rotated and the sleeve (103b) can be rotated around the core or kept stationary. (The means for rotating the core and/or the sleeve are not shown in the figure).
  • a device (118)for generating a DC-voltage and an AC-voltage is connected to the sleeve of the magnetic brush and applies a DC-voltage (DC1) and an AC-field (AC1) to said sleeve (the toner bearing surface).
  • DC1 and AC1 and AC1 and the toner bearing surface optionally a further means for providing a DC and/or AC-potential (116) to the toner bearing surface may be present.
  • the amount of developer on the toner bearing surface is regulated by a doctor blade (113).
  • the device further comprises a back electrode (105) connected to a DC voltage source applying a voltage DC4 to the back electrode.
  • An image receiving substrate (108) is passed by means for moving the substrate (107) in the direction of arrow A between the printhead structure (106) and the back electrode by conveying means (107).
  • the difference between voltage DC4 and voltage DC1 applies a DC-propulsion field wherein a flow of toner particles (104) is created from the sleeve of the magnetic brush (the toner bearing surface) to the image receiving substrate on the back electrode.
  • the AC-field (AC1) on the sleeve of the magnetic brush makes the flow (104)of toner particles denser than when no AC-field would be present.
  • the control electrodes (106a) can selectively be connected, over switch (115) either to a device (119) for generating a DC-voltage (DC3) and an AC-field (AC3) or to said device (118) for generating a DC-voltage (DC1) and an AC-voltage (AC1).
  • a further means for providing a DC and/or AC-potential (117) to the control electrode may be present.
  • the flow of charged toner particles is image-wise modulated in the vicinity of the control electrodes.
  • the voltage applied to the control electrodes can be set to a value totally blocking the passage of the toner particles (i.e. when switch 115 connects the control electrodes to when DC1 and AC1).
  • the control electrode is grounded for printing full density through the printing aperture it controls and the grey levels are printed by time modulating the switching of a switch (115) between the devices providing DC3 and AC3 and the devices providing DC1 and AC1.
  • no device (119) for generating a DC-voltage (DC3) and an AC-field (AC3) is incorporated, and the switch (115) switches the control electrode between the device (118) connected to the toner bearing surface and the ground. It is possible, as described above, to apply a DC-voltage (DC3) having a value different from DC1 and/or an AC-field (AC3) having a value different from the AC-field (AC1) to the control electrode, for partially blocking the printing apertures and at the same time again time modulating the switching of switch 115. By doing so, the number of grey levels that can be printed can be enhanced.
  • control electrodes in said printhead structure and , designed according to this invention are placed at a distance d from the toner bearing surface, a spacer (110) keeps the distance d constant during operation of the device.
  • the control electrode paths extend in both directions perpendicular to the toner bearing member to a length larger than the printing nip in which toner particles can be selected for said printing apertures. In practice said minimal length is at least 1 mm, preferably at least 3 mm.
  • the device comprises further means (109) for fixing the toner particles to the image receiving substrate.
  • a printhead structure according to this invention is included in a device wherein the toner bearing surface is kept at a DC-potential of 0 V (i.e. it is grounded).
  • a DC voltage of 0 V is applied to the control electrode, and again no AC-field exists over the gap between the toner bearing surface and the control electrodes when the printing aperture has to block the toner flow.
  • a DC voltage of + 100 V is applied to the control electrode, on top of which an AC-potential with peak to peak voltage 400 V and a frequency 1/ ⁇ 1 is applied. Again, an AC-field exists over the gap between the toner bearing surface and the control electrodes when the printing aperture has to let toner particles pass freely.
  • Such a device is shown in figure 6.
  • the toner bearing surface is the surface of the sleeve of a magnetic brush
  • a device according to a further embodiment of the invention is shown, wherein the toner bearing surface is the surface of an applicator carrying toner particles derived from a non-magnetic mono-component developer.
  • the device, shown in figure 6 is the same as the one shown in figure 5, except for the toner bearing surface, so only the numericals different from those used in figure 4 will be described.
  • a roller (112) is present, having a surface.
  • Toner particles are applied by means of a feeding roller (111) made of porous foamed polymers.
  • a developer mixing blade (114) mixes and transports said non-magnetic mono-component developer towards said feeding roller.
  • a doctor blade (113) regulates the thickness of the charged toner particles upon the surface said roller (112), i.e. on the toner bearing surface.
  • a device (118) only generating a DC-potential (DC1) is connected to the sleeve of the toner bearing surface.
  • the control electrodes (106a) can over a switch 115 selectively be connected to a device (119) providing an AC-field (AC3) and a device providing a DC-voltage (DC3) or to the device (118) providing a DC-voltage (DC1) on the toner bearing surface.
  • the DC potential (DC3) and the AC-field (AC3) are image-wise modulated in order to modulate the toner flow through the control electrodes.
  • the voltage applied to the control electrodes can be varied between a value totally blocking the passage of the toner particles when the switch (115) connects the control electrode to the device (118) providing a DC-voltage (DC1), and a value leaving the toner flow pass totally unimpeded when the switch (115) connects the control electrode to the device (119) providing a DC-voltage (DC3)and an AC-field (AC3).
  • DC3 and AC3 make it again possible, as described above, to increase the number of grey levels that can be printed.
  • Grey levels can then be printed by bringing the control electrode and the toner bearing surface only a fraction of the line time (LT) to the same electric potential, thus blocking the toner flow for only a fraction of the line time (LT).
  • This time modulation is a preferred embodiment of the present invention. It is possible, for increasing the number of grey levels that can be printed, to have a DC-voltage on the control electrodes deviating from the DC-voltage on the toner bearing surface and/or to have an AC-voltage on the control electrodes deviating from the AC-voltage on the toner bearing surface. Thus it is possible to choose the strength of the AC-field over the gap between the toner bearing surface and the control electrodes such that so that, e.g.
  • D max is formed, but only three quarter of D max ., half of D max , a quarter of D max , etc.
  • the insulating material, used for producing a 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 terephthalate, polyethylene naphthalate, etc.), polyolefines, an epoxy resin, an organosilicon resin, rubber, etc.
  • Insulating material useful in the present invention, has an 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 back electrode (105) of a DEP device can also be made to cooperate with the printhead structure according to this invention, 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-A- 4, 568 ,955 and US-A-4, 733, 256 .
  • the back electrode, co-operating with the printhead structure can also comprise one or more flexible PCB's (Printed Circuit Board).
  • a printhead structure according to this invention has the advantage that from a printhead structure with multiple rows, all rows can be used for printing during the printing period, thus making it possible to print faster than with the method described in DE-A-197 16 115.
  • the invention also encompasses a method for direct electrostatic printing comprising the steps of :
  • the printhead structure The printhead structure.
  • a printhead structure (106) was made from a polyimide film of 50 ⁇ m thickness (106c), single sided coated with a 5 ⁇ m thick copper film.
  • the printhead structure (106) had one row of printing apertures.
  • Each of said control electrodes had conductive paths in a direction parallel to the printing direction over 10 mm and was connected over 2 M ⁇ resistors to a HV 507 (trade name) high voltage switching IC, commercially available through Supertex, USA, that was powered from a high voltage power amplifier.
  • the printing apertures were rectangular shaped with dimensions of 200 by 100 ⁇ m.
  • the dimension of the central part (C1) of the rectangular shaped copper control electrodes was 320 by 300 ⁇ m, the line width of the C2 and C3 segments was 100 ⁇ m.
  • the apertures were spaced at a 400 ⁇ m pitch.
  • Said printhead structure was fabricated in the following way. First of all the control electrode pattern was etched by conventional copper etching techniques. The apertures were made by a step and repeat focused excimer laser making use of the control electrode patterns as focusing aid. After excimer burning the printhead structure was cleaned by a short isotropic plasma etching cleaning. Finally a thin coating of PLASTIK70, commercially available from Griffin Chemie, was applied over the control electrode side of said printhead structure.
  • the toner delivery means The toner delivery means
  • the toner delivery means was a commercially available toner cartridge comprising non magnetic mono component developer, the COLOR LASER TONER CARTRIDGE MAGENTA (M3760GIA), for the COLOR LASER WRITER (Trade names of Apple Computer, USA).
  • the toner bearing surface is the surface of an aluminium roller (112), whereon tone particles are applied by a feeding roller (111) The toner particles carried a negative charge.
  • the printhead structure mounted in a PVC-frame (116), was bent with frictional contact over the surface of the roller of the toner delivery means.
  • a 50 ⁇ m thick polyurethane coating was used as self-regulating spacer means (110).
  • a back electrode was present behind the paper whereon the printing proceeded, the distance between the back electrode (105) and the back side of the printhead structure (i.e. control electrodes (106a)) was set to 1000 ⁇ m and the paper travelled at 200 cm/min.
  • the back electrode was connected to a high voltage power supply, applying a voltage DC4 of + 1000 V to the back electrode.
  • a sinusoidally changing AC voltage AC1 with 400 V peak to peak and a frequency of 3 kHz was applied and a DC-offset (DC1) of -100 V.
  • the DC-propulsion field i.e. the potential difference between DC4 and DC1, was 1100 V.
  • an (image-wise-selected) voltage was applied selected from 0 V (printing,a pixel of maximum density) or the same voltage as applied to the toner delivery means (DC1 and AC1 with the same amplitude and phase as the voltages applied to the toner bearing surface: printing a pixel with minimum density).
  • Grey scale images of a human face and control wedges from maximum to minimum density were printed during several minutes after which the image quality and toner accumulation upon said printhead structure was observed. Said printing example showed extremely good results.

Landscapes

  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
EP98204099A 1997-12-18 1998-12-04 Structure d'une tête d'impression utilisée dans un dispositif d'impression électrostatique directe comprenant des électrodes symétriques à la surface d'impression Withdrawn EP0924089A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP98204099A EP0924089A1 (fr) 1997-12-18 1998-12-04 Structure d'une tête d'impression utilisée dans un dispositif d'impression électrostatique directe comprenant des électrodes symétriques à la surface d'impression

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP97204014 1997-12-18
EP97204014 1997-12-18
EP98204099A EP0924089A1 (fr) 1997-12-18 1998-12-04 Structure d'une tête d'impression utilisée dans un dispositif d'impression électrostatique directe comprenant des électrodes symétriques à la surface d'impression

Publications (1)

Publication Number Publication Date
EP0924089A1 true EP0924089A1 (fr) 1999-06-23

Family

ID=26147175

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98204099A Withdrawn EP0924089A1 (fr) 1997-12-18 1998-12-04 Structure d'une tête d'impression utilisée dans un dispositif d'impression électrostatique directe comprenant des électrodes symétriques à la surface d'impression

Country Status (1)

Country Link
EP (1) EP0924089A1 (fr)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3689935A (en) 1969-10-06 1972-09-05 Electroprint Inc Electrostatic line printer
US5128695A (en) 1990-07-27 1992-07-07 Brother Kogyo Kabushiki Kaisha Imaging material providing device
US5307092A (en) 1989-09-26 1994-04-26 Array Printers Ab Image forming device
WO1994026527A1 (fr) * 1993-05-18 1994-11-24 Array Printers Ab Procede d'impression sans impact utilisant une matrice multiplexee d'electrodes unitaires commandees et dispositif d'execution du procede
US5477250A (en) * 1992-11-13 1995-12-19 Array Printers Ab Device employing multicolor toner particles for generating multicolor images
US5596356A (en) 1995-10-26 1997-01-21 Hewlett-Packard Company Toner ejection printer with dummy electrode for improving print quality
US5650809A (en) 1994-03-28 1997-07-22 Brother Kogyo Kabushiki Kaisha Image recording apparatus having aperture electrode with dummy electrodes for applying toner image onto image receiving sheet
EP0795802A1 (fr) 1996-03-15 1997-09-17 Agfa-Gevaert N.V. Structure d'une tête d'impression fabriquée par revêtement autocatalytique sur un substrat plastique
DE19716115A1 (de) 1996-04-19 1997-10-30 Array Printers Ab Verfahren zur Verbesserung der Druckqualität einer Bildaufzeichnungsvorrichtung
EP0812269A1 (fr) 1995-02-27 1997-12-17 Ohio Electronic Engravers, Inc. Procede et appareil de centrage du cylindre d'une machine a graver

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3689935A (en) 1969-10-06 1972-09-05 Electroprint Inc Electrostatic line printer
US5307092A (en) 1989-09-26 1994-04-26 Array Printers Ab Image forming device
US5128695A (en) 1990-07-27 1992-07-07 Brother Kogyo Kabushiki Kaisha Imaging material providing device
US5477250A (en) * 1992-11-13 1995-12-19 Array Printers Ab Device employing multicolor toner particles for generating multicolor images
WO1994026527A1 (fr) * 1993-05-18 1994-11-24 Array Printers Ab Procede d'impression sans impact utilisant une matrice multiplexee d'electrodes unitaires commandees et dispositif d'execution du procede
US5650809A (en) 1994-03-28 1997-07-22 Brother Kogyo Kabushiki Kaisha Image recording apparatus having aperture electrode with dummy electrodes for applying toner image onto image receiving sheet
EP0812269A1 (fr) 1995-02-27 1997-12-17 Ohio Electronic Engravers, Inc. Procede et appareil de centrage du cylindre d'une machine a graver
US5596356A (en) 1995-10-26 1997-01-21 Hewlett-Packard Company Toner ejection printer with dummy electrode for improving print quality
EP0795802A1 (fr) 1996-03-15 1997-09-17 Agfa-Gevaert N.V. Structure d'une tête d'impression fabriquée par revêtement autocatalytique sur un substrat plastique
DE19716115A1 (de) 1996-04-19 1997-10-30 Array Printers Ab Verfahren zur Verbesserung der Druckqualität einer Bildaufzeichnungsvorrichtung

Similar Documents

Publication Publication Date Title
US5714992A (en) Printhead structure for use in a DEP device
EP0780740B1 (fr) Dispositif d'impression électrostatique directe avec une structure d'une tête d'impression avec ouvertures à fente
EP0710898B1 (fr) Dispositif d'impression électrostatique directe avec rangées d'ouvertures de dimensions plus petites et plus grandes
EP0812696B1 (fr) Structure de tête d'impression avec une électrode d'écran spécifique
EP0924089A1 (fr) Structure d'une tête d'impression utilisée dans un dispositif d'impression électrostatique directe comprenant des électrodes symétriques à la surface d'impression
EP0911706B1 (fr) Dispositif d'impression électrostatique directe avec une structure d'une tête d'impression conventionelle et un circuit de couplage AC à l'électrode de commande
EP0740224B1 (fr) Imprimante électrostatographique directe (DEP)
US6109731A (en) Device for direct electrostatic printing with a conventional printhead structure and AC-coupling to the control electrodes
EP0963852B1 (fr) Méthode d'impression et contrôle pour une tête d'impression avec électrodes de déviation pour l'impression électrostatique directe
EP0710897B1 (fr) Dispositif d'impression électrostatique direct avec électrode individuelle d'écran et de commande par ouverture
US6102523A (en) Printer for large format printing using a direct electrostatic printing (DEP) engine
US6003975A (en) DEP printhead structure and printing device having an improved printing electrode structure
EP0895867A2 (fr) Appareil d'impression électrostatique directe comprenant une électrode de bord et un champ de courant alternatif sur la surface des moyens d'alimentation en toner
US6059398A (en) Printhead structure having electrodes not extending to the edge of printing apertures
EP0849645A1 (fr) Appareil d'impression pour imprimer à grand format utilsant un appareil d'impression électrostatique direct
EP0731394B1 (fr) Dispositif pour l'impression électrostatique directe comprenant une structure à brosse magnétique et à tête d'impression à géométrie particulière
EP0983858B1 (fr) Méthode d'impression et contrôle pour une tête d'impression avec système d'électrodes de déviation pour l'impression électrostatique directe
EP0963853B1 (fr) Méthode d'impression dans un appareil d'impression électrostatique directe ayant une structure de tête d'impression avec électrodes de déflexion et moyens de contrôle électrique pour cettes électrodes de déflexion
US5900893A (en) Direct electrostatic printing device wherein the speeds of a magnetic brush and a receiving substrate are related to each other
JPH11240196A (ja) 静電式直接印刷装置用印刷ヘツド構造体
JP3159940B2 (ja) 特別なシールド電極を有するプリントヘッド構造体
US6151047A (en) Direct electrostatic printing apparatus having a magnetic brush with a core rotating at high speed
US6109729A (en) Direct electrostatic printing device having a printhead structure with control electrodes on one side of a slit aperture
EP0978769A1 (fr) Méthode d'impression pour un dispositif d'impression électrostatique direct comprenant des moyens d'alimentation en toner formés d'un rouleau de transport de toner chargé, d'une brosse magnétique et d'une unité de nettoyage
EP1003083B1 (fr) Appareil d'impression pour imprimer à grand format, comportant une unité centrale de conditionnement pour commander et surveiller la condition du révélateur

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): BE DE FR GB

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

17P Request for examination filed

Effective date: 19991223

AKX Designation fees paid

Free format text: BE DE FR GB

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: AGFA-GEVAERT

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20020701