# US 6,793,325 B2 · Direct printing apparatus and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,793,325 B2 - Document ID: US6793325B2 - Status: Granted - Kind: B2 - Application number: 10/433,262 - Filed: 2003-06-02 - Published: 2004-02-26 - Granted: 2004-09-21 - Earliest claimed: 2003-06-02 - Assignees: Matsushita Electric Industrial Co., Ltd. - Inventors: Filip Alm - Web page: https://patentgrep.com/patent/US6793325B2 ## CPC - B41J 2/4155: {for direct electrostatic printing [DEP]} - G03G 15/346: {by modulating the powder through holes or a slit} - G03G 2217/0025: where the toner starts moving from behind the electrode array, e.g. a mask of holes - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A direct printing method and apparatus in which a computer generated image information is converted into a pattern of electrostatic fields, which selectively transport electrically charged toner particles from a particle source (3) toward a back electrode through a printhead structure including a plurality of appertures and control electrodes arranged in conjunction to the apertures whereby the charged toner particles are deposited in image configuration on an image receiving surface caused to move relative to the printhead structure. Control means is arranged to address an amount of charged toner particles corresponding to at least 35 charged toner particles per addressed dot at least for a part of the image location areas. ## Claims ### Claim 1 An image forming apparatus, in which an image information is converted into a pattern of electrostatic fields for modulating a transport of charged toner particles from a particle carrier towards an image receiving surface, said image forming apparatus including: a background voltage source for producing a background electric field which enables a transport of charged toner particles from said particle carrier towards said image receiving surface; a printhead structure arranged in said background electric field, including a plurality of apertures and control electrodes arranged in conjunction to the apertures; control voltage sources for supplying control potentials to said control electrodes in accordance with the image information to selectively permit or restrict the transport of charged toner particles from the particle carrier through the apertures; said image receiving surface being arranged for movement in relation to the printhead structure for intercepting the transported charged toner particles in an image configuration; control means being arranged for controlling the amount of charged toner particles addressed to the respective dot location of said image receiving surface; characterized in that said control means is arranged to address an amount of charged toner particles corresponding to at least 35 charged toner particles per addressed dot at least for a part of the image location areas. ### Claim 2 (depends on 1) An image forming apparatus according to claim 1, characterized in that said control means is arranged to address an amount of charged toner particles corresponding to 2*1010 particles/m2 image location area (2*104 particles/mm2 image location area) at least for a part of the image location area. ### Claim 3 (depends on 2) An image forming apparatus according to claim 2, characterized in that for full optical density said control means is arranged to address an amount of charged toner particles corresponding to 2*1010 particles/m2 image location area (2*104 particles/mm2 image location area). ### Claim 4 (depends on 1) An image forming apparatus according to claim 1, characterized in that said control means is arranged to address an amount of charged toner particles so that the projected area of said particles on the image receiving surface before fusing is at least 0.5 times the image location area of said image receiving surface at least for a part of the image location area. ### Claim 5 (depends on 4) An image forming apparatus according to claim 4, characterized in that for full optical density said control means is arranged to address an amount of charged toner particles so that the projected area of said particles on the image receiving surface before fusing is at least 0.5 times the image location area of said image receiving surface. ### Claim 6 (depends on 1) An image forming apparatus according to claim 1, characterized in that the projected area of said charged toner particles after fusing is at least 0.8 times the image location area of said image receiving surface at least for a part of the image location areas. ### Claim 7 (depends on 6) An image forming apparatus according to claim 6, characterized in that for full optical density the projected area of said charged toner particles after fusing is at least 0.8 times the image location area of said image receiving surface. ### Claim 8 (depends on 1) An image forming apparatus according to claim 1, characterized in that said control means for full optical density is arranged to address at least 35 charged toner particles per addressed dot at 600*600 dpi (dots per square inch). ### Claim 9 (depends on 8) An image forming apparatus according to claim 8, characterized in that said control means for half optical density is arranged to address at least 15 and preferably at least 25 charged toner particles per addressed dot at 600*600 dpi (dots per square inch). ### Claim 10 (depends on 9) An image forming apparatus according to claim 9, characterized in that said control means for half optical density is arranged to address at least 50 and preferably at least 70 charged toner particles per addressed dot at 300*300 dpi (dots per square inch). ### Claim 11 (depends on 1) An image forming apparatus according to claim 1, characterized in that said control means for full optical density is arranged to address at least 140 charged toner particles per addressed dot at 300*300 dpi (dots per square inch). ### Claim 12 (depends on 1) An image forming apparatus according to claim 1, characterized in that the dot size is at least 400*400 dpi (dots per square inch). ### Claim 13 (depends on 1) An image forming apparatus according to claim 1, characterized in that said toner particles are non magnetic. ### Claim 14 (depends on 1) An image forming apparatus according to claim 1, characterized in that the apparatus further comprises a back electrode, wherein the image receiving surface is a first face of the back electrode from which the toner particles in said image configuration can be transferred to an information carrier. ### Claim 15 (depends on 1) An image forming apparatus according to claim 1, characterized in that the image receiving surface is a first face of an information carrier which also acts as a back electrode. ### Claim 16 (depends on 1) An image forming apparatus according to claim 1, characterized in that the apparatus further comprises an intermediate image receiving member and a back electrode, wherein the image receiving surface is a first face of the intermediate image receiving member and the back electrode is located facing a second face of the intermediate image receiving member, so that the toner particles in said image configuration can be transferred from the first face of the intermediate image receiving member to an information carrier. ### Claim 17 (depends on 1) An image forming apparatus according to claim 1, characterized in that the apparatus further comprises a back electrode, wherein the image receiving surface is a first face of an information carrier and the back electrode is located facing a second face of the information carrier. ### Claim 18 An image forming method in which an image information is converted into a pattern of electrostatic fields including: modulating a transport of charged toner particles from a particle carrier towards an image receiving surface; producing a background electric field to enable a transport of said charged toner particles from said particle carrier towards said image receiving surface; providing an apertured printhead structure in said background electric field, and control electrodes arranged in conjunction to the apertures; connecting voltage sources to said control electrodes to supply control potentials to said control electrodes produce a pattern of electrostatic fields in accordance with the image information to selectively permit or restrict the transport of charged toner particles from the particle carrier through the apertures; and conveying said image receiving surface in relation to the printhead structure for intercepting the transported charged toner particles in image configuration; controlling the amount of charged toner particles addressed to the respective dot location of said image receiving surface; characterized in controlling the amount of charged toner particles so as to address an amount to the respective dot location so that at least 35 charged toner particles are addressed per dot at least for a part of the image location areas. ### Claim 19 (depends on 18) An image forming method according to claim 18, controlling the amount of charged toner particles so as to address an amount corresponding to 2*1010 particles/m2 image location area (2*104 particles/mm2 image location area) at least for a part of the image location areas. ### Claim 20 (depends on 19) An image forming method according to claim 19, characterized in controlling the amount of charged toner particles so as for full optical density address an amount corresponding to 2*1010 particles/m2 image location area (2*104 particles/mm2 image location area). ### Claim 21 (depends on 19) An image forming method according to claim 19, characterized in controlling the amount of charged toner particles so as to address an amount of charged toner particles so that the projected area of said particles on the image receiving surface before fusing is at least 0.5 times the image location area of said image receiving surface at least for a part of the image location areas. ### Claim 22 (depends on 21) An image forming method according to claim 21, characterized in controlling the amount of charged toner particles so as for full optical density address an amount of charged toner particles so that the projected area of said particles on the image receiving surface before fusing is at least 0.5 times the image location area of said image receiving surface. ### Claim 23 (depends on 18) An image forming method according to claim 18, characterized in controlling the amount of charged toner particles addressed to the respective dot location so that the projected area of said charged toner particles after fusing is at least 0.8 times the image location area of said image receiving surface at least for a part of the image location areas. ### Claim 24 (depends on 23) An image forming method according to claim 23, characterized in controlling the amount of charged toner particles so as for full optical density address an amount of charged toner particles so that the projected area of said particles on the image receiving surface after fusing is at least 0.8 times the image location area of said image receiving surface. ### Claim 25 (depends on 18) An image forming method according to claim 18, characterized in controlling the amount of charged toner particles addressed to the respective dot location so that for full optical density at least 35 charged toner particles are addressed per dot at 600*600 dpi (dots per square inch). ### Claim 26 (depends on 25) An image forming method according to claim 25, characterized in controlling the amount of charged toner particles addressed to the respective dot location so that for half optical density at least 15 and preferably at least 25 charged toner particles are addressed per addressed dot at 600*600 dpi (dots per square inch). ### Claim 27 (depends on 18) An image forming method according to claim 18, characterized in controlling the amount of charged toner particles addressed to the respective dot location so that for full optical density at least 140 charged toner particles are addressed per addressed dot at 300*300 dpi (dots per square inch). ### Claim 28 (depends on 27) An image forming method according to claim 27, characterized in controlling the amount of charged toner particles addressed to the respective dot location so that for half optical density at least 50 and preferably at least 70 charged toner particles are addressed per addressed dot at 300*300 dpi (dots per square inch). ### Claim 29 (depends on 18) An image forming method according to claim 18, characterized in that the dot size is at least 400*400 dpi (dots per square inch). ### Claim 30 (depends on 18) An image forming method according to claim 18, characterized in that said toner particles are non magnetic.