EP1091264A1 - Dispositif d'impression électrostatique directe dans lequel des particules de toner chargées sont appliquées à un convoyeur en contact avec l'élément d'alimentation de toner d'un système de développement monocomposant non-magnétique - Google Patents

Dispositif d'impression électrostatique directe dans lequel des particules de toner chargées sont appliquées à un convoyeur en contact avec l'élément d'alimentation de toner d'un système de développement monocomposant non-magnétique Download PDF

Info

Publication number
EP1091264A1
EP1091264A1 EP99203242A EP99203242A EP1091264A1 EP 1091264 A1 EP1091264 A1 EP 1091264A1 EP 99203242 A EP99203242 A EP 99203242A EP 99203242 A EP99203242 A EP 99203242A EP 1091264 A1 EP1091264 A1 EP 1091264A1
Authority
EP
European Patent Office
Prior art keywords
toner particles
toner
charged toner
dispensing part
conveyer
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Withdrawn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
EP99203242A
Other languages
German (de)
English (en)
Inventor
Guido c/o Agfa-Gevaert N.V. IIE 3800 Desie
Lode c/o Agfa-Gevaert N.V. IIE 3800 Deprez
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 EP99203242A priority Critical patent/EP1091264A1/fr
Publication of EP1091264A1 publication Critical patent/EP1091264A1/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • 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
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/0806—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller
    • G03G15/0808—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer on a donor element, e.g. belt, roller characterised by the developer supplying means, e.g. structure of developer supply roller
    • 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 a recording method and an apparatus for use in the process of Direct Electrostatic Printing (DEP), in which an image is created upon a receiving substrate 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.
  • DEP Direct Electrostatic Printing
  • toner particles are deposited directly in an image-wise way on a receiving substrate, the latter not bearing any image-wise latent electrostatic image.
  • 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 perpendicular 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.
  • One of the problems with this type of printing devices is that charged toner particles can accumulate upon the printhead structure and in the printing apertures. Due to this problem the achievable printing density does not remain constant in the time, while the charged toner particles accumulated on the printhead structure may change the electrical field wherein the charged toner particles are propelled towards the substrate and the toner particles accumulated in the printing apertures can physically block the toner passage.
  • a first way disclosed to avoid the clogging of printing apertures relies on the design of the printhead structure, the printing apertures or both.
  • US-A-4 876 561 it is disclosed to prevent clogging of the printing apertures by making the apertures large enough and/or the thickness of the isolating layer small enough.
  • US-A-5 307 092 it is disclosed to apply an antistatic coating to the electrodes in the printhead so that any tribocharge that accumulates during writing can be grounded and the accumulation of toner particles on the printhead avoided.
  • a printhead structure for a DEP (Direct Electrostatic Printing) device is disclosed that comprises an insulating material and an oblong slit having control electrodes on the edge of it, instead of having apertures.
  • DEP Direct Electrostatic Printing
  • an edge electrode is described so that instead of individual apertures or a larger slit, an even larger free zone between the toner source and the receiver exists, resulting in even better properties regarding clogging of the printhead structure
  • WST Wrong Sign Toner
  • edge electrode as printhead structure as described in US-A-5 625 392 solves the problem of clogging, but suffers from the drawback that, in order to obtain a good image contrast between image parts of low density and image parts of high density, the overall applied propulsion field between the toner source and the receiver on the back electrode must be set to a rather low value, so that per unit of time only a moderate amount of toner particles can be attracted so that only a moderate printing speed is possible when high optical density is desired.
  • the pulling magnetic brush was found to be insufficient for removing all toner particles from the CTC so that there have been proposals to use scraper blades to clean the CTC so that the pushing magnetic brush applies fresh toner particles to a virgin surface of the CTC.
  • the implementation of a scraper blade requires that a relatively high amount of toner is presented to said CTC-roller in a single contact: i.e. a typical amount of charged toner applied to said CTC-roller of about 5 to 10 g/m 2 has to be deposited in a single pass.
  • a further object of the invention is to provide a method for direct electrostatic printing wherein it is possible to combine high speed printing, low clogging of the printing apertures, high maximum density, low or no incidence of ghost images and a printing quality that is constant over a long period of time.
  • the first object of the invention is realised by providing a DEP device comprising :
  • the second object of the invention is realised by providing a method for Direct Electrostatic Printing (DEP) comprising the steps of :
  • Figure 1 shows schematically a DEP device according to the prior art in which a non-magnetic mono-component development system is used to jump charged toner particles over an air gap upon the surface of a charged toner conveyer roller by applying a voltage difference.
  • Figure 2 shows schematically a DEP device according to the present invention in which the toner dispensing part of a non-magnetic mono-component development system is in contact with a charged toner conveyer roller.
  • Figure 3 shows schematically a DEP device according to the present invention in which the toner dispensing part of a non-magnetic mono-component development system is in contact with a charged toner conveyer roller, wherein the toner dispensing part is in belt form.
  • Figure 4 shows schematically a DEP device according to the present invention in which the toner dispensing part of a non-magnetic mono-component development system is in contact with a charged toner conveyer roller, wherein the toner dispensing part is a roller made of resilient material.
  • Figure 5 shows very schematically a DEP device according to the present invention wherein the toner particles are recycled.
  • CTC Charged toner conveyer
  • the CTC can be a roller, a belt, a roller with a core surrounded by a sleeve, etc.
  • toner dispensing part is used to indicate that part of a non-magnetic mono-component development system that has a surface carrying charged toner particles and from where said charged toner particles can be dispensed to a CTC or directly extracted towards the printhead structure.
  • part marked (108) is the "toner dispensing part” in the sense of this definition.
  • Ghost images can be seen in even grey patches that are printed after printing an image : when in the grey level some impression of the previously printed image is left, this image is a "ghost image”.
  • a prior art DEP device wherein charged toner particles are jumped from a toner dispensing part of a non-magnetic mono-component development system is shown in figure 1.
  • This constellation is equivalent to the one disclosed in DE-A 197 45 561.
  • a non-magnetic mono component development system (101) contains non-magnetic toner particles (102), stirred by stirring means (110), a toner propagating roller (104) rotating in the direction of arrow D, bringing non-magnetic toner particles on the sleeve (108a) placed around a core (108b) of a toner dispensing part (108).
  • the toner dispensing part with toner particles on it rotates in the direction of arrow C and brings the toner particles past a doctor blade (112) and a charging part (113) so that the toner dispensing part carries charged non-magnetic toner particles.
  • the toner dispensing part is connected to a DC-voltage source (V5) and is placed with respect to a charged toner conveyer (103) so that between this toner conveyer and the toner dispensing part a gap, g, is left.
  • the charged toner conveyer is connected to a DC source (V1) and an optional AC-source (AC2).
  • the CTC (103) is mounted opposite to a back electrode (105) connected to a DC-voltage source V4.
  • creates an electric field wherein a flow (111) of charged toner particles from the surface of the CTC to the back electrode is generated.
  • An image receiving substrate (109) passes, in the direction of arrow A, adjacent to the back electrode in said flow. Between the image receiving substrate and the surface of the CTC, a printhead structure (106) is placed in the flow of charged toner particles.
  • the printhead structure includes an array of printing apertures (107),shield electrode (106b) common 'to all printing apertures and connected to voltage source V2.
  • the zone between the array of printing apertures and the surface of the CTC forms a development zone in which a toner flow can be initiated(111).
  • Control electrodes (106a) are associated with the printing apertures and are connected to a voltage source, V3, that can apply a voltage that varies in accordance with image data to the control electrode for selectively let charged toner particles pass the printing apertures and stop the charged toner particles from passing the apertures.
  • a means (114) for recovering an recycling the toner particles is located near the CTC and downstream of the development zone.
  • This prior art device makes it possible to have almost no clogging of the printing apertures and toner adhesion to the printhead structure, but the device does not perform very well in terms of delivering high maximum density, low or no incidence of ghost images and a printing quality that is constant over a long period of time.
  • the amount of charged toner particles that can be provided upon said surface of said CTC-roller is high enough so that "ghost images" can be prevented, although the printing speed is measured in several meters/minute.
  • FIG 2 a first possible embodiment of a DEP device according to this invention is schematically shown.
  • the numbering of the parts in figure 2 is the same as in figure 1, but the sleeve (108a) of the toner dispensing part is in contact with the CTC.
  • the sleeve (108a) and the core (108b), which is driven by a motor (not shown), of the toner dispensing part (108) are construed so that the sleeve has an inner diameter slightly larger than the outer diameter of the core, so that in the contact point between the toner dispensing part (108) and the CTC (103) a slack (115) is formed.
  • the surface over which the CTC and the toner dispensing part make contact is enlarged, with the beneficial effect that a large amount of toner particles is brought on the CTC by every revolution of the toner dispensing part.
  • a dispensing part (108) wherein the sleeve has an inner diameter slightly larger than the outer diameter of the core, the sleeve has a thickness of about 150 ⁇ m and the a diameter of about 20 mm.
  • the sleeve is preferably made of a conductive and flexible material, e.g., organic polymers, nylon, nickel, organic polymeric materials filled with carbon black, etc.
  • the drive roller is also preferably made from conductive material and is connected to a voltage source or ground potential.
  • the toner dispensing part is made as an endless belt (108) that is moved around bearings (116) at least one of them being driven by a motor (not shown).
  • the belt is arranged so that again a slack (115) is formed where the toner dispensing part is in contact with the CTC.
  • the belt is preferably made of a conductive and flexible material, e.g., organic polymers as such, e.g., nylon, polystyrene, polyvinylchloride, polyester, polyacrylate, polycarbonate, polyimide, etc or an organic polymeric material filled with carbon black or other conductive particles.
  • the belt can also be made from a metal as nickel, stainless steel, etc.
  • the toner dispensing part is made as a roller having a small rigid core for driving it and wherein said roller is covered with a resilient material, e.g., polyurethane rubber, conductive rubber, etc. It can also be a sponge roller.
  • the roller is arranged so that again the surface over which the toner dispensing part is in contact with the CTC is quite large.
  • the charged toner particles, that are not used in the printing process and remain on the CTC are further displaced downstream of the printing zone to a cleaning station (114) in which a complete removal of charged (or discharged) toner particles from the surface of said CTC is effected to have a bare surface again. Then the CTC moves further on towards the toner dispensing part of the non-magnetic mono-component development system, located upstream of the development zone where again a fresh population of charged toner particles, wherein no wrong sign toner particles are present, is provided on the surface of the CTC.
  • the non-used toner particles are removed from the toner bearing surface of the CTC with a scraper blade, which can be made from a plastic material or of metal.
  • a scraper blade which can be made from a plastic material or of metal.
  • scraper blade made of stainless steel.
  • the non-used toner particles that have been removed from the CTC are recycled in the container and dispenser of non-magnetic mono-component developer.
  • a DEP device wherein charged toner particles, that are not used in the printing process and remain on the CTC, are further displaced downstream of the printing zone to a cleaning station in which a complete removal of charged (or discharged) toner particles from the surface of said CTC is effected and from where these toner particles are recycled to the container for non-magnetic mono-component developer is shown in figure 5.
  • a device for direct electrostatic printing is very schematically shown (from the non-magnetic mono-component development system only the container and the "toner dispensing part" are shown), comprising :
  • the device further comprises means for recycling the collected toenr particles to the container (101) for non-magnetic mono-component developer.
  • the back electrode is a solid electrode, however the back electrode (105) of a DEP device according to this invention can also be made to co-operate 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-A-4, 568,955 and US-A-4,733,256.
  • the back electrode, cooperating with the printhead structure can also comprise one or more flexible PCB's (Printed Circuit Board).
  • a DEP device can also function without a back electrode when it is used for printing on an insulating image receiving substrate.
  • a conductive layer is applied upon said insulating substrate and said conductive layer is connected via a conductive charge applying device to a voltage source, and the substrate whereon the printing proceeds is then its own back electrode.
  • Such device has been described in EP-A-823 676 and EP-A-952 498.
  • 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 according to the present invention, be different from the location shown in the figures.
  • a DEP device using two electrodes (106a and 106b) on printhead 106 is shown, it is possible to implement a DEP device, according to the present invention, incorporating printhead structures with different constructions. 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.
  • the apertures in these printhead structures can have a constant diameter, or can have a broader entrance or exit diameter.
  • Typical printhead structures useful in DEP devices according to the present invention have been described in, e.g., US-A-5 889 540, US-A-5 714 992, EP-A-753 413, EP-A-780 740, EP-A-812 696, EP-A-816 944, EP-A-924 089, etc.
  • 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 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.
  • Voltage V5 is applied to the surface of the sleeve (108a) of the toner dispensing part of the non-magnetic monocomponent development system. If so desired, an additional AC-source can beneficially be connected to the surface of the sleeve (108a) of the toner dispensing part of said non-magnetic monocomponent development system.
  • the invention encompasses also a method for Direct Electrostatic Printing (DEP) comprising the steps of :
  • toner particles with an absolute average charge over mass ratio (
  • the charge to mass ratio of the toner particles is measured by mixing the toner particles with carrier particles, and after 15 min of charging the q/m-ratio is measured as described in US-A-5 880 760. Said toner particles were pulled under vacuum from said CTC-roller to an accurately weighted filter paper (weight was WP in g), which was shielded in a Faraday cage.
  • the amount of charge that arrived, after about 5 minutes vacuum pulling and after an accurate surface area of said CTC-roller was cleaned from said toner particles, at said filter paper was measured with a Coulomb meter in ⁇ C.
  • the filter paper with the toner particles was weighted again, giving weight WPT in g.
  • the charge to mass ratio was then determined as ⁇ C/(WPT-WP).
  • the charge to mass ratio is taken as the absolute value, as a DEP device according to this invention can function either with negatively charged toner particles or with positively charged toner particles depending on the polarity of the potential difference between V1 and V4.
  • 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 that is incorporated herein by reference.
  • negatively chargeable toner particles with both low average charge and narrow charge distribution are provided by adding to toner particles, comprising a negatively chargeable toner resin, at least one resistivity lowering substance having a volume resistivity lower than the volume resistivity of the resin, wherein said substance(s) is fare) capable of lowering the volume resistivity of said resin by a factor of at least 3.3 when present in said binder in a concentration of 5 % by weight relative to the weight of said binder.
  • positively charged toner particles with both low average charge and narrow charge distribution are provided by adding to the toner particles, having a triboelectrically positively chargeable thermoplastic resin, at least one substance having a volume resistivity lower than the volume resistivity of the resin, wherein said substance(s) when present in said binder in a concentration of 5 % by weight lower(s) the volume resistivity of said binder by a factor of at least 3.3.
  • resisivity decreasing substances are within the following classes of compounds : onium compounds, metal salts containing relatively large (bulky) anionic groups, betaines, amino acids, metal complex compounds, ionically conductive polymers in which the polymer chain carries anionic groups, e.g. sulphonate groups, electronically conductive polymers, e.g. polyanilines, polypyrroles and polythiophenes.
  • a printhead structure (106) was made from a polyimide film of 50 ⁇ m thickness, double sided coated with a 5 ⁇ m thick copper film.
  • the printhead structure (106) had two rows of printing apertures.
  • Each of said control electrodes 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 360 by 120 ⁇ m.
  • the dimension of the central part of the rectangular shaped copper control electrodes was 500 by 260 ⁇ m.
  • a common shield electrode (106b) was,arranged around the aperture zone leaving a free polyimide zone of 1620 ⁇ m.
  • Said printhead structure was fabricated in the following way. First of all the control and shield 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 charged toner conveyer (CTC) The charged toner conveyer (CTC)
  • the CTC was a cylinder with a sleeve made of aluminium, coated with TEFLON (trade name of Du Pont, Wilmington, USA) with a surface roughness of 2.2 ⁇ m (Ra-value) and a diameter of 30 mm.
  • the charged toner conveyer (103) was connected to a DC power supply of 0V.
  • the printhead structure mounted in a PVC-frame, was bent with frictional contact over the surface of the roller of the charged toner conveyer roller.
  • a polyurethane coating was used as self-regulating spacer means.
  • 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 was set to 1000 ⁇ m and the paper travelled a linear speed (LSM) of 300 cm/min.
  • the back electrode was connected to a high voltage power supply, applying a voltage V4 of + 1000 V to the back electrode.
  • the printed image consisted of an ISO original image ('portrait' and 'cafeteria' of the ISO 12640 standard) followed by a 50% grey area and a grey-wedge). If the image quality was very good, then after a continuous printing time of 1 hour the printhead structure was checked for toner adhesion and/or nozzle blocking, and the printouts were analysed for variation in maximum density and appearance of ghost images.
  • the criteria for ghost images were set as follows: in the area of 50% grey level density, the visibility of the previously printed ISO images was checked.
  • non-magnetic mono-component development system commercially available from Apple (Cyan Toner Cartridge M3757 G/A for the APPLE COLOR LASER WRITER 12/600 PS (trade name) printer) was used to jump toner particles directly towards the printhead structure.
  • the front roller of said non-magnetic mono-component development system was placed at 230 ⁇ m from the front side of said printhead structure.
  • To the shield electrode a voltage of + 110 V was applied, to said control electrodes image wise modulated voltages of 0 and + 280 V were applied.
  • the back electrode was located at 1000 ⁇ m from the back side of said printhead structure, and a voltage of + 1250 V was applied to it.
  • the image receiving paper was travelling at a speed of 3 m/min, while the roller of the non-magnetic mono-component development system was rotating at a linear speed of 6 m/min.
  • Printing was performed during 1 hour. After one hour a severe toner adhesion was observed upon said printhead structure, however, only a few nozzle's were blocked. From the final printouts it could be observed that especially after the periods of D min -printing nozzle blocking frequently occurred but the blocked nozzle's could be opened spontaneously during the D max -writing conditions.
  • the back electrode was located at 1000 ⁇ m from the back side of said printhead structure, and a voltage of + 1250 V was applied to it.
  • the image receiving paper was travelling at a speed of 3 m/min, while the roller of the non-magnetic mono-component development system was rotating at a linear speed of 6 m/min. Printing could not be performed during 1 hour because severe toner adhesion to said printhead structure led to irreversible nozzle blocking and disappearing image density. ghost images in the image part of 50% grey density of the first images could not be detected, so that an "OK" value was tabulated for this property.
  • the magnetic brush was 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.
  • the magnetic brush was connected to 155 V DC-offset.
  • the toner concentration of the developer (commercially available developer for the AGFA CHROMAPRESS (trade name) printer) used was 5 %.
  • the surface of said CTC-roller was located at 260 ⁇ m from the front side of said printhead structure.
  • a voltage of + 110 V was applied, to said control electrodes image wise modulated voltages of 0 and + 280 V were applied.
  • the back electrode was placed at 1000 ⁇ m from the back side of said printhead structure and connected to a DC-potential of + 1250 V.
  • the image receiving paper was travelling at a speed of 3 m/min, while the linear speed of the CTC-roller and magnetic brush roller were 4.5 and 19 m/min, respectively. Both magnetic brush roller and CTC-roller were rotated in an opposite direction.
  • a non-magnetic mono-component development system commercially available from Apple (Cyan Toner Cartridge M3757 G/A for the Apple Color Laser Writer 12/600 PS printer) was used to jump toner particles over a gap to a CTC.
  • the distance between said front-roller of said non-magnetic mono-component development system and said charged toner conveyer roller was 230 ⁇ m
  • the DC-potential applied towards the sleeve of said front-roller of said non-magnetic mono-component development system was + 45 V.
  • the surface of said CTC-roller was located at 240 ⁇ m from the front side of said printhead structure.
  • a voltage of + 110 V was applied, to said control electrodes image wise modulated voltages of 0 and + 280 V were applied.
  • the back electrode was placed at 1000 ⁇ m from the back side of said printhead structure and connected to a DC-potential of + 1250 V.
  • the image receiving paper was travelling at a speed of 3 m/min, while the linear speed of the CTC-roller and front-roller of said non-magnetic mono-component development system were 5 and 10 m/min, respectively. Both front-roller of said non-magnetic mono-component development system and CTC-roller were rotated in an opposite direction.
  • the image receiving paper was travelling at a speed of 3 m/min, while the linear speed of the CTC-roller and front-roller of said non-magnetic mono-component development system were 5 and 10 m/min, respectively. Both the front-roller of said non-magnetic mono-component development system and the CTC-roller were rotated in an opposite direction.
  • the toner adhesion to said printhead structure was greatly improved if compared with the example in which the front-roller of said non-magnetic mono-component development system was used to directly propel charged toner particles to said printhead structure ("OK"), both the image density significantly changed over the printing time (“NOT OK”), and ghost images were notably visible (“NOT OK"). All printing results are also summarised in table 1.
  • the charged toner conveyer roller was fed from a non-magnetic mono-component development system, commercially available from Lexmark (Cyan Toner Cartridge 1361752 for the LEXMARK OPTRA SC1275 (trade name) printer).
  • the front roller i.e. the "toner dispensing part" of said non-magnetic mono-component development system, was in direct contact over the charged toner particles with said CTC-roller.
  • a DC-potential of + 170 V was applied towards the sleeve of said front-roller of said non-magnetic mono-component development system.
  • the doctor blade in said non-magnetic mono-component development system cartridge was connected to a voltage of -20 V, and the conductive strip in said cartridge was connected to a voltage source of + 135 V.
  • the surface of said CTC-roller was located at 260 ⁇ m from the front side of said printhead structure.
  • To the shield electrode a voltage of + 110 V was applied, to said control electrodes image wise modulated voltages of 0 and + 280 V were applied.
  • the back electrode was placed at 1000 ⁇ m from the back side of said printhead structure and connected to a DC-potential of + 1250 V.
  • the image receiving paper was travelling at a speed of 3 m/min, while the linear speed of the CTC-roller and front-roller of said non-magnetic mono-component development system were 5 and 10 m/min, respectively.
  • the front-roller ("toner dispensing part") of said non-magnetic mono-component development system was rotated in a direction opposite to the direction wherein the CTC-roller was rotated. Even after a printing period of 1 hour, no significant toner adhesion to said printhead structure was observed, nor any white stripe in the final image printouts could be found somewhere ("OK").

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
EP99203242A 1999-10-04 1999-10-04 Dispositif d'impression électrostatique directe dans lequel des particules de toner chargées sont appliquées à un convoyeur en contact avec l'élément d'alimentation de toner d'un système de développement monocomposant non-magnétique Withdrawn EP1091264A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP99203242A EP1091264A1 (fr) 1999-10-04 1999-10-04 Dispositif d'impression électrostatique directe dans lequel des particules de toner chargées sont appliquées à un convoyeur en contact avec l'élément d'alimentation de toner d'un système de développement monocomposant non-magnétique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP99203242A EP1091264A1 (fr) 1999-10-04 1999-10-04 Dispositif d'impression électrostatique directe dans lequel des particules de toner chargées sont appliquées à un convoyeur en contact avec l'élément d'alimentation de toner d'un système de développement monocomposant non-magnétique

Publications (1)

Publication Number Publication Date
EP1091264A1 true EP1091264A1 (fr) 2001-04-11

Family

ID=8240710

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99203242A Withdrawn EP1091264A1 (fr) 1999-10-04 1999-10-04 Dispositif d'impression électrostatique directe dans lequel des particules de toner chargées sont appliquées à un convoyeur en contact avec l'élément d'alimentation de toner d'un système de développement monocomposant non-magnétique

Country Status (1)

Country Link
EP (1) EP1091264A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0811894A1 (fr) * 1996-06-06 1997-12-10 Agfa-Gevaert N.V. Méthode d'impression d'information sur des substrats munis d'éléments de sécurité
DE19745561A1 (de) * 1996-10-16 1998-04-23 Array Printers Ab Vorrichtung zur Verbesserung der Druckqualität einer Bildaufzeichnungsvorrichtung
US5783347A (en) * 1996-06-27 1998-07-21 Brother Kogyo Kabushiki Kaisha Positively chargeable single-component developer and image-forming apparatus for using the same
US5899609A (en) * 1996-07-09 1999-05-04 Aetas Peripheral Corporation Developing unit and developing method
EP0945275A2 (fr) * 1998-03-24 1999-09-29 Matsushita Electric Industrial Co., Ltd. Appareil et procédé de formation d'images

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0811894A1 (fr) * 1996-06-06 1997-12-10 Agfa-Gevaert N.V. Méthode d'impression d'information sur des substrats munis d'éléments de sécurité
US5783347A (en) * 1996-06-27 1998-07-21 Brother Kogyo Kabushiki Kaisha Positively chargeable single-component developer and image-forming apparatus for using the same
US5899609A (en) * 1996-07-09 1999-05-04 Aetas Peripheral Corporation Developing unit and developing method
DE19745561A1 (de) * 1996-10-16 1998-04-23 Array Printers Ab Vorrichtung zur Verbesserung der Druckqualität einer Bildaufzeichnungsvorrichtung
US5956064A (en) * 1996-10-16 1999-09-21 Array Printers Publ. Ab Device for enhancing transport of proper polarity toner in direct electrostatic printing
EP0945275A2 (fr) * 1998-03-24 1999-09-29 Matsushita Electric Industrial Co., Ltd. Appareil et procédé de formation d'images

Similar Documents

Publication Publication Date Title
US7200352B2 (en) Developing apparatus, developing method, image forming apparatus, image forming method and cartridge thereof
EP0435549A2 (fr) Tête d'impression à orifices pour imprimante électrostatique directe
EP0415700B1 (fr) Dispositif pour retirer le toneur chargé avec la mauvaise polarité dans une imprimante électrostatique directe
US5040004A (en) Belt donor for direct electrostatic printing
JPH0647298B2 (ja) 粉体画像記録方法
JP2006251104A (ja) 現像装置、プロセスカートリッジ及び画像形成装置
JPH11133747A (ja) 現像装置
JP2007147991A (ja) 現像装置、プロセスカートリッジ、画像形成装置および現像方法
JP2002307740A (ja) 静電搬送装置、現像装置、画像形成装置及びトナー供給装置
JP3237818B2 (ja) 印刷ヘツド構造体及びｄｅｐ装置
EP1091264A1 (fr) Dispositif d'impression électrostatique directe dans lequel des particules de toner chargées sont appliquées à un convoyeur en contact avec l'élément d'alimentation de toner d'un système de développement monocomposant non-magnétique
EP0812696B1 (fr) Structure de tête d'impression avec une électrode d'écran spécifique
EP0763785B1 (fr) Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur
EP0736822B1 (fr) Dispositif d'impression électrostatique directe
US5984443A (en) Direct electrostatic printing device which uses a gas stream to provide a cloud of toner particles
US6246424B1 (en) Device for large format printing comprising a single central conditioning unit for controlling and monitoring the condition of the developer
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
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
EP0849645A1 (fr) Appareil d'impression pour imprimer à grand format utilsant un appareil d'impression électrostatique direct
US5738009A (en) Method for direct electrostatic printing (DEP)
EP0731394B1 (fr) Dispositif pour l'impression électrostatique directe comprenant une structure à brosse magnétique et à tête d'impression à géométrie particulière
EP0458579A2 (fr) Marquage électrostatique
EP1003083B1 (fr) Appareil d'impression pour imprimer à grand format, comportant une unité centrale de conditionnement pour commander et surveiller la condition du révélateur
EP1058165A1 (fr) Dispositif d'impression électrostatique directe où les particules de toner chargées sont amenées à proximité de la structure d'impression à l'aide d'un pistolet de pulvérisation électrostatique de poudre
US6059398A (en) Printhead structure having electrodes not extending to the edge of printing apertures

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): 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: 20011011

AKX Designation fees paid

Free format text: 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: 20030501