EP0736822B1 - A device for direct electrostatic printing (DEP) - Google Patents
A device for direct electrostatic printing (DEP) Download PDFInfo
- Publication number
- EP0736822B1 EP0736822B1 EP19960200845 EP96200845A EP0736822B1 EP 0736822 B1 EP0736822 B1 EP 0736822B1 EP 19960200845 EP19960200845 EP 19960200845 EP 96200845 A EP96200845 A EP 96200845A EP 0736822 B1 EP0736822 B1 EP 0736822B1
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- EP
- European Patent Office
- Prior art keywords
- dep
- magnetic brush
- toner
- sub
- sleeve
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- 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.)
- Expired - Lifetime
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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
- G03G15/34—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
-
- 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-P-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.
- the human eye is extremely sensitive to small density fluctuations, it is not an easy task to print at a certain grey scale density with a high degree of homogeneity.
- a kind of "banding" i.e. stripes of slightly different densities can be seen in a density pattern that is intended to be totally homogeneous and even.
- EP-A 617 335 a DEP device is shown where the toner particles are extracted from a magnetic brush whereon only magnetic toner particles are present, in this disclosure the sleeve of the magnetic brush rotates at a speed of 150 rpm and the substrate moves at a linear speed of 300 cm/min.
- US-A 4 491 855 also a DEP device is shown where the toner particles are extracted from a magnetic brush whereon only magnetic toner particles are present, in this disclosure the sleeve of the magnetic brush rotates at a speed of 150 rpm and the substrate is said to move at a linear speed of 1500 cm/min.
- DEP Direct Electrostatic Printing
- said receiving substrate (109) moves at a speed V sub ⁇ 28 cm/min and said sleeve of said magnetic brush assembly is rotated at a speed V rot so that V rot / V sub ⁇ 5 rotations/cm.
- Fig. 1 is a schematic illustration of a possible embodiment of a DEP device according to the present invention.
- DEP Direct Electrographic Printing
- All these devices are able to perform grey scale printing either by voltage modulation or by time modulation of the voltages applied to the control electrodes.
- Most of the disclosed DEP devices operate with a Charged Toner Conveyer (CTC) to bring toner particles in the vicinity of a printhead structure.
- CTC Charged Toner Conveyer
- the toner particles are magnetic, as disclosed in, e.g., EP-A 617 335, or are non-magnetic. In that latter case the toner particles are applied to the CTC by a conventional magnetic brush from a multi-component developer comprising toner particles and magnetic carrier particles. Examples of such devices are a.o.
- the DEP-devices as described in EP-A 675 417, operating with a multicomponent developer comprising magnetic carrier particles and toner particles and wherein the toner particles are directly brought to the printhead structure by a magnetic brush, can give raise to a kind of "banding", especially in the direction of movement of the toner receiving member, in printed patches of even density. This was especially so when fast printing was to be achieved.
- fast printing means that the toner receiving substrate travels past the printhead structure at a speed V sub ⁇ 10 cm/min. This "banding" is due to density fluctuations, during the time that the printing of the even density patch proceed.
- V sub ⁇ 10 cm/min and the ratio between V rot and V sub fulfils preferably the equation V rot /V sub ⁇ 5 rotations/cm.
- V sub ⁇ 28 cm/min and the ratio between V rot and V sub fulfils preferably the equation V rot /V sub ⁇ 5 rotations/cm.
- V sub ⁇ 28 cm/min and V rot /V sub ⁇ 10 rotations/cm.
- the dimensions of V rot /V sub are a number of rotation over cm.
- the printhead structure used in a preferred embodiment of the present invention is made in such a way that reproducible printing is possible without clogging and with accurate control of printing density.
- Such a printhead structure has been described in EP-A 719 648 and is preferentially stretched over a 2-bar or 4-bar frame as described in EP-A 712 056.
- a non limitative example of a device for implementing a DEP method using toner particles according to the present invention comprises (fig 1):
- the printhead structure (106) comprises one continuous electrode surface, hereinafter called “shield electrode” (106b) facing in the shown embodiment the toner delivering means and a complex addressable electrode structure, hereinafter called “control electrode” (106a) around printing apertures (107), facing, in the shown embodiment, the receiving substrate (109) in said DEP device.
- Said printing apertures are arranged in an array structure for which the total number of rows can be chosen according to the field of application. In a preferred embodiment as described later on e.g. an array of printing apertures consisting of 2 individual rows of apertures can be used.
- the location and/or form of the shield electrode (106b) and the control electrode (106a) can, in other embodiments of a device for a DEP method using toner particles according to the present invention, be different from the location shown in fig. 1.
- a DEP method using toner particles according to the present invention using devices with different constructions of the printhead (106). It is, e.g. possible to implement a DEP method with a device having a printhead comprising only one electrode structure as well as with a device having a printhead comprising more than two electrode structures. It is also possible to implement a DEP device according to the present invention using a mesh isolated wires as printhead structure, as disclosed in e.g., US 5,036,341.
- the apertures in these printhead structures can have a constant diameter, or can have a broader entrance or exit diameter.
- 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-P 4,568,955 and US-P 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 timebasis or grey-level basis.
- Voltage V4 is applied to the back electrode behind the toner receiving member. In other embodiments of the present invention multiple voltages V2 0 to V2 n and/or V4 0 to V4 n can be used.
- the magnetic brush assembly 103 used in a DEP device according to the present invention can be either of the type with stationary core and rotating sleeve or of the type with rotating core and rotating or stationary sleeve.
- a magnetic brush of the rotating sleeve/stationary core is preferred in a DEP device according to the present invention.
- a magnetic brush with rotating sleeve and stationary core said magnetic brush having a curvature in the development zone fulfilling the equation I : R > C 2 4.25B + 0.25 wherein the curvature R of said magnetic brush in the development zone is expressed as the radius (in mm) of a circle that best fits to said curvature of said magnetic brush in the development zone, B is the distance between the surface of said sleeve of said magnetic brush to the surface of said printhead structure, facing said magnetic brush and C is the extension (in mm) of the array of printing apertures (107) in the direction of the movement of said receiving substrate (109) measured from the middle of the apertures in the first row to the middle of the apertures in the last row.
- a magnetic brush fulfilling the equation above has been described in EP-A 731 394.
- 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 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 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 in EP-A 675 417, titled “A method and device for direct electrostatic printing (DEP)".
- toner particles with an absolute average charge corresponding to 1 fC ⁇
- the charge distribution is narrow, i.e. shows a distribution wherein the coefficient of variability ( ⁇ ), i.e. the ratio of the standard deviation to the average value, is equal to or lower than 0.33.
- ⁇ coefficient of variability
- 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-A 675 417, titled "A method and device for direct electrostatic printing (DEP)".
- 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 according to the present invention 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 106a 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.
- a printhead structure 106 was made from a polyimide film of 50 ⁇ m thickness, double sided coated with a 17 ⁇ m thick copper film.
- the printhead structure 106 had two rows of printing apertures (107), said apertures having a square shape of 200 by 200 micron.
- each aperture had a square copper electrode of 50 micron around each aperture, said 2 rows of apertures isolated from each other by a 100 micron broad isolation zone.
- This printhead structure had a resolution of 127 dpi (50 dots per cm) and was fabricated using the technique of plasma etching.
- Each of said control electrodes was individually addressable from a high voltage power supply.
- a common shield electrode was present on the front side of the printhead structure, facing the toner delivery means.
- the toner delivery means 101 was a stationary core/rotating sleeve type magnetic brush (103) 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 assembly 103 was constituted of the so called magnetic roller, which in this case contained inside the roller assembly a stationary magnetic core, showing nine magnetic poles with an open position to enable used developer to fall off from the magnetic roller.
- the magnetic roller contained also a sleeve, fitting around said stationary magnetic core, and giving to the magnetic brush assembly an overall diameter of 20 mm.
- 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 assembly.
- the sleeve was rotating at a speed as tabulated in table 1, the internal elements rotating at such a speed as to conform to a good internal transport within the development unit.
- the magnetic brush assembly 103 was connected to an AC power supply with a square wave oscillating field of 600 V at a frequency of 3.0 kHz with 0 V DC-offset.
- 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 propoxylated 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 structural formula : (CH 3 ) 3 N + C 16 H 33 Br - was added in a quantity of 0.5 % with respect to the binder. It was found that - by mixing with 5 % of said ammonium salt - the volume resistivity of the applied binder resin was lowered to 5x10 14 ⁇ .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 resulting particle size distribution of the separated toner measured by Coulter Counter model Multisizer (tradename), was found to be 6.3 ⁇ m average by number and 8.2 ⁇ m average 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. tribo-electric charging of the toner-carrier mixture was performed by mixing said mixture in a standard tumbling set-up for 10 min.
- the distance between the back electrode 105 and the back side of the printhead structure 106 (i.e. control electrodes 106a) was set to 150 ⁇ m.
- the receiving substrate (109) was paper and moved at various speeds (V sub in cm/min) as indicated in table 1.
- To the individual control electrodes an (imagewise) voltage V3 between 0 V and -300 V was applied.
- the backelectrode 105 was connected to a high voltage power supply of +400 V.
- To the sleeve of the magnetic brush an AC voltage of 600 V at 3.0 kHz was applied, without DC offset.
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- General Physics & Mathematics (AREA)
- Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
Description
- a layer of insulating material, called isolation layer ;
- a shield electrode consisting of a continuous layer of conductive material on one side of the isolation layer ;
- a plurality of control electrodes formed by a segmented layer of conductive material on the other side of the isolation layer ; and
- at least one row of apertures.
- a back electrode (105),
- a printhead structure (106), comprising an array of apertures through which a particle flow can be electrically modulated,
- means for moving a receiving substrate (109) at a speed Vsub ≥ 10 cm/min between said back electrode (105) and said printhead structure (106),
- a toner delivery means (101), at the front side of said printhead structure, with a magnetic brush assembly (103) comprising a core and a sleeve, wherein said sleeve of said magnetic brush assembly is coupled to means for rotating it at a speed Vrot higher than 100 rpm (rotations per minute) and
- developer in said toner delivery means containing at least toner particles and magnetically attractable carrier particles;
Vrot / Vsub ≥ 2 rotations/cm.
The DEP-devices, as described in EP-A 675 417, operating with a multicomponent developer comprising magnetic carrier particles and toner particles and wherein the toner particles are directly brought to the printhead structure by a magnetic brush, can give raise to a kind of "banding", especially in the direction of movement of the toner receiving member, in printed patches of even density. This was especially so when fast printing was to be achieved. In the context of the present invention, fast printing means that the toner receiving substrate travels past the printhead structure at a speed Vsub ≥ 10 cm/min. This "banding" is due to density fluctuations, during the time that the printing of the even density patch proceed. We have found that reproducible density modulation as a function of printing time is possible without the introduction of time-propagating electrical signals applied to either the control electrodes (106a), the shield electrode (106b) or the toner application module (103). The most important parameter found to improve the "banding" (i.e. diminish said banding) was the rotation speed of the sleeve of the magnetic brush. This proved to be true both for a magnetic brush of the stationary core/rotating sleeve type and for a magnetic brush of the rotating core/rotating sleeve type. It was found that when the rotation speed (Vrot) of said sleeve was higher than 100 rotations per minute (rpm) the banding phenomenon was clearly diminished. It was found that the banding phenomenon was even more diminished when Vrot (in rpm) was tuned to speed (Vsub) in cm/min of the receiving substrate moving between the back electrode and the printhead structure so that
the curvature R of said magnetic brush in the development zone is expressed as the radius (in mm) of a circle that best fits to said curvature of said magnetic brush in the development zone, B is the distance between the surface of said sleeve of said magnetic brush to the surface of said printhead structure, facing said magnetic brush and C is the extension (in mm) of the array of printing apertures (107) in the direction of the movement of said receiving substrate (109) measured from the middle of the apertures in the first row to the middle of the apertures in the last row. A magnetic brush fulfilling the equation above has been described in EP-A 731 394.
A scraper blade was used to force developer to leave the magnetic roller. And on the other side a doctoring blade was used to meter a small amount of developer onto the surface of said magnetic brush assembly. The sleeve was rotating at a speed as tabulated in table 1, the internal elements rotating at such a speed as to conform to a good internal transport within the development unit. The
In the same table 1 the homogeneity of the even density patches is given under heading SIG and have been measured according to test A as described hereafter.
The homogeneity of a patch of even densities was expressed with respect to the visibility of density differences, i.e. to the way a human observer would perceive these differences. Therefore, the measured values of density variations (in fact a well known σD) were recalculated to density variations as perceived by a human observer. In practice, a sample of even density patches printed on paper was scanned in the direction of the movement of the receiving substrate with a slit of 2 mm by 27 µm and a spatial resolution of 10 µm. The sampling distance was 1 cm and 1024 data points were sampled. The sampling proceeded in reflection mode and the reflectances where measured.
Said obtained scan of the reflectances was converted to a "perceived" image by means of a perception model. This conversion comprises the following steps :
Dvis = 2.00 when the reflectance (R) is lower than 0.01, while the eye can differentiate reflectances below 0.01.
In the thus obtained "perceived" image the standard deviation of the density fluctuation (SIG) was calculated.
The results of this analysis are given in table 1. A value for the parameter SIG smaller than 0.045 means acceptable image quality, in terms of homogeneity of even density patterns, a value smaller than 0.030 means excellent quality, a value of 0.025 to 0.020 is typical for offset high-quality.
Experiment n° | Vsub cm/min | Vrot rpm | Vsub/Vrot | SIG |
1 | 56 | 150 | 2.6 | 0.041 |
2 | 56 | 300 | 5.3 | 0.040 |
3 | 28 | 300 | 10.7 | 0.039 |
4 | 14 | 300 | 21.4 | 0.028 |
5 | 14 | 105 | 7.5 | 0.041 |
6 | 28 | 1000 | 35.7 | 0.022 |
7 | 28 | 50 | 1.8 | 0.060 |
8 | 56 | 100 | 1.8 | 0.048 |
9 | 56 | 60 | 1.1 | 0.049 |
Claims (5)
- A DEP (Direct Electrostatic Printing) device comprisinga back electrode (105),a printhead structure (106), comprising an array of apertures through which a particle flow can be electrically modulated,means for moving a receiving substrate (109) at a speed Vsub ≥ 10 cm/min between said back electrode (105) and said printhead structure (106),a toner delivery means (101), at the front side of said printhead structure, with a magnetic brush assembly (103) comprising a core and a sleeve, wherein said sleeve of said magnetic brush assembly is coupled to means for rotating it at a speed Vrot higher than 100 rpm (rotations per minute) anddeveloper in said toner delivery means containing at least toner particles and magnetically attractable carrier particles; characterised in that said means for rotating said sleeve of said magnetic brush assembly and said means for moving said substrate are equipped for being operated so that
Vrot / Vsub ≥ 2 rotations/cm. - A DEP device according to claim 1, wherein said means for rotating said sleeve of said magnetic brush assembly and said means for moving said substrate are equipped for being operated so that Vrot / Vsub ≥ 5 rotations/cm.
- A DEP device according to claim 2, wherein said means for moving said receiving substrate (109) is equipped for moving it at a speed Vsub ≥ 28 cm/min.
- A DEP device according to claim 1, wherein said means for moving said receiving substrate (109) is equipped for moving it at a speed Vsub ≥ 28 cm/min and said means for rotating said sleeve of said magnetic brush assembly is equipped to be operated so as to have a Vrot so that Vrot / Vsub ≥ 10 rotation/cm.
- A DEP device according to claim 1, wherein said magnetic brush is of the stationary core/rotating sleeve type.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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EP19960200845 EP0736822B1 (en) | 1995-04-03 | 1996-03-28 | A device for direct electrostatic printing (DEP) |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP95200834 | 1995-04-03 | ||
EP95200834 | 1995-04-03 | ||
EP19960200845 EP0736822B1 (en) | 1995-04-03 | 1996-03-28 | A device for direct electrostatic printing (DEP) |
Publications (2)
Publication Number | Publication Date |
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EP0736822A1 EP0736822A1 (en) | 1996-10-09 |
EP0736822B1 true EP0736822B1 (en) | 2001-08-22 |
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EP19960200845 Expired - Lifetime EP0736822B1 (en) | 1995-04-03 | 1996-03-28 | A device for direct electrostatic printing (DEP) |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6406132B1 (en) | 1996-03-12 | 2002-06-18 | Array Printers Ab | Printing apparatus of toner jet type having an electrically screened matrix unit |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH09314889A (en) * | 1996-05-28 | 1997-12-09 | Sharp Corp | Image forming equipment |
US6074112A (en) * | 1996-12-19 | 2000-06-13 | Agfa-Gevaert | Printer for large format printing |
US6102523A (en) * | 1996-12-19 | 2000-08-15 | Agfa-Gevaert | Printer for large format printing using a direct electrostatic printing (DEP) engine |
EP0965455A1 (en) | 1998-06-15 | 1999-12-22 | Array Printers Ab | Direct electrostatic printing method and apparatus |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US4491855A (en) * | 1981-09-11 | 1985-01-01 | Canon Kabushiki Kaisha | Image recording method and apparatus |
JP2520500B2 (en) * | 1990-05-30 | 1996-07-31 | 三田工業株式会社 | Image forming device |
US5327169A (en) * | 1992-08-05 | 1994-07-05 | Xerox Corporation | Masked magnetic brush direct writing for high speed and color printing |
JPH06274026A (en) * | 1993-03-24 | 1994-09-30 | Hitachi Metals Ltd | Direct recording method |
-
1996
- 1996-03-28 EP EP19960200845 patent/EP0736822B1/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6406132B1 (en) | 1996-03-12 | 2002-06-18 | Array Printers Ab | Printing apparatus of toner jet type having an electrically screened matrix unit |
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