Inventor · disambiguated record
Masafumi Ohta
Also filed as: OHTA MASAFUMI · SAKAI KIYOSHI
63 granted patents·1,324 citations·filing 1975–2012
99Inventor score
Top patents by PatentIndex Score
63 records- 0197US5492784APositively-chargeable single-layered type electrophotographic photoconductorRICOH KK·Filed 1993·Granted Feb 20, 1996·106 cites·9 claims
- 0297US5420288AElectroluminescent device comprising oxadiazole compounds luminescent material, oxadiazole compounds for the device, and method of producing oxadiazole compoundsRICOH KK·Filed 1993·Granted May 30, 1995·83 cites·41 claims
- 0397US4245021AElectrophotographic element having charge transport layerRICOH KK·Filed 1979·Granted Jan 13, 1981·85 cites·16 claims
- 0495US4272598AElectrophotographic material containing disazo compoundsRICOH KK·Filed 1978·Granted Jun 9, 1981·23 cites·54 claims
- 0594US5747204AElectrophotographic photoconductor and aromatic polycarbonate resin for use in the sameRICOH KK·Filed 1996·Granted May 5, 1998·56 cites·26 claims
- 0693US6316577B1Electrophotographic photoconductor and aromatic polycarbonate resin for use thereinHODOGAYA CHEMICAL CO LTD·Filed 2000·Granted Nov 13, 2001·34 cites·22 claims
- 0793US5656401AElectroluminescent device comprising oxadiazole compounds luminescent material, oxadiazole compounds for the device, and method of producing oxadiazole compoundsRICOH KK·Filed 1994·Granted Aug 12, 1997·76 cites·21 claims
- 0893US5153073AElectroluminescent deviceRICOH KK·Filed 1991·Granted Oct 6, 1992·80 cites·8 claims
- 0991US6027846AElectrophotographic photoconductor and aromatic polycarbonate resin for use thereinRICOH KK·Filed 1996·Granted Feb 22, 2000·49 cites·7 claims
- 1091US5597925AMethod of producing oxadiazole compoundsRICOH KK·Filed 1995·Granted Jan 28, 1997·67 cites·2 claims
- 1191US4596754AElectrophotographic printing original plate and electrophotographic plate making process using the printing original plateRICOH KK·Filed 1985·Granted Jun 24, 1986·38 cites·12 claims
- 1290US5610309AElectroluminescent device comprising oxadiazole compounds luminescent material, oxadiazole compounds for the device, and method of producing oxadiazole compoundsRICOH KK·Filed 1995·Granted Mar 11, 1997·63 cites·3 claims
- 1390US4507471ATrisazo compounds prepared from 4,4',4"-triaminotriphenylamine and 2-hydroxy-3-phenylcarbamoylbenzo[a]carbazole derivativesRICOH KK·Filed 1982·Granted Mar 26, 1985·19 cites·5 claims
- 1489US4279981AElectrophotographic elements containing trisazo compoundsRICOH KK·Filed 1978·Granted Jul 21, 1981·28 cites·66 claims
- 1588US5118986AElectroluminescent deviceRICOH KK·Filed 1990·Granted Jun 2, 1992·36 cites·15 claims
- 1686US4251614ANovel disazo compounds, process for the preparation of same and application of said disazo compounds and analogues thereof to electrophotographic sensitive materialsRICOH KK·Filed 1978·Granted Feb 17, 1981·21 cites·68 claims
- 1784US4251613ADisazo compounds, process for preparation of same and application of said disazo compounds and analogues thereof to electrophotographic sensitive materialsRICOH KK·Filed 1978·Granted Feb 17, 1981·22 cites·60 claims
- 1883US5830980AElectrophotographic photoconductor, aromatic polycarbonate resin for use in the same, and method of producing the aromatic polycarbonate resinRICOH KK·Filed 1997·Granted Nov 3, 1998·28 cites·8 claims
- 1983US4365014AElectrophotographic photoconductorRICOH KK·Filed 1979·Granted Dec 21, 1982·17 cites·6 claims
- 2081US4293628AElectrophotographic elements containing disazo compoundsRICOH KK·Filed 1978·Granted Oct 6, 1981·11 cites·24 claims
- 2181US4260672AElectrophotographic sensitive element having a photoconductive disazo pigmentRICOH KK·Filed 1978·Granted Apr 7, 1981·19 cites·16 claims
- 2280US4299896AElectrophotographic sensitive materials containing a disazo pigmentRICOH KK·Filed 1978·Granted Nov 10, 1981·19 cites·16 claims
- 2377US4582771ADisazo compound, method for preparing the same, and electrophotographic element containing the same for use in electrophotographyRICOH KK·Filed 1984·Granted Apr 15, 1986·16 cites·16 claims
- 2477US4264695AElectrophotographic photosensitive material with electron donors and electron acceptorsRICOH KK·Filed 1980·Granted Apr 28, 1981·37 cites·9 claims
- 2576US8530124B2Hydroxygallium phthalocyanine composite pigment, electrophotographic photoconductor containing the same, and image forming device and process cartridge for image forming device using the sameSAKAGUCHI HIROMI·Filed 2010·Granted Sep 10, 2013·2 cites·9 claims
- 2676US5604065AElectrophotographic photoconductor and triphenylamine compound for use thereinRICOH KK·Filed 1995·Granted Feb 18, 1997·21 cites·11 claims
- 2775US4314015AElectrophotographic sensitive materials containing disazo compoundsRICOH KK·Filed 1980·Granted Feb 2, 1982·18 cites·16 claims
- 2874US4992109APhotoelectric conversion elementRICOH KK·Filed 1989·Granted Feb 12, 1991·28 cites·22 claims
- 2972US4247614AElectrophotographic element containing a disazo pigmentRICOH KK·Filed 1979·Granted Jan 27, 1981·13 cites·114 claims
- 3071US5489495AElectrophotographic photoconductor and diamine compounds for use in the sameRICOH KK·Filed 1994·Granted Feb 6, 1996·15 cites·31 claims
- 3171US4567124AElectrophotographic element with trisazo photoconductor and an amine substituted charge transfer materialRICOH KK·Filed 1984·Granted Jan 28, 1986·15 cites·7 claims
- 3270US5672756ATriphenylamine compound for use in electrophotographic photoconductorsRICOH KK·Filed 1996·Granted Sep 30, 1997·16 cites·6 claims
- 3370US5093210AElectroluminescent deviceRICOH KK·Filed 1990·Granted Mar 3, 1992·32 cites·3 claims
- 3470US4242260A2-Hydroxy-3-carbonylanilinonaphth-1-yl disazo derivatives and 1-phenyl-3-methyl-5-hydroxypyrazol-4-yl disazo derivatives of 1,4-bis(4-aminostyryl) benzeneRICOH KK·Filed 1978·Granted Dec 30, 1980·10 cites·28 claims
- 3568US8383304B2Gallium phthalocyanine compound, and image bearing member, image forming method, image forming apparatus, and process cartridge using the gallium phthalocyanine compoundRICOH CO LTD·Filed 2011·Granted Feb 26, 2013·1 cites·12 claims
- 3665US8232376B2Azo compound and method of preparing the azo compoundOHTA MASAFUMI·Filed 2008·Granted Jul 31, 2012·2 cites·6 claims
- 3763US8380109B2Image forming apparatus and process cartridgeRICOH CO LTD·Filed 2009·Granted Feb 19, 2013·2 cites·12 claims
- 3863US4426327A3,6-Disazo-9-ethyl carbazole compoundsRICOH KK·Filed 1980·Granted Jan 17, 1984·11 cites·3 claims
- 3963US4135928AElectrophotographic light-sensitive memberRICOH KK·Filed 1977·Granted Jan 23, 1979·9 cites·5 claims
- 4062US5631404ADiamine compounds for use in electrophotographic photoconductorsRICOH KK·Filed 1995·Granted May 20, 1997·12 cites·21 claims
- 4161US7858278B2Electrophotographic photoreceptor, and image forming apparatus and process cartridge using the electrophotographic photoreceptorRICOH CO LTD·Filed 2007·Granted Dec 28, 2010·2 cites·16 claims
- 4261US4830942AElectrophotographic photoconductorRICOH KK·Filed 1987·Granted May 16, 1989·12 cites·15 claims
- 4360US4663442ADisazo triphenylamine compoundsRICOH KK·Filed 1985·Granted May 5, 1987·10 cites·8 claims
- 4458US8541557B2Azo compound and method of preparing the azo compoundOHTA MASAFUMI·Filed 2012·Granted Sep 24, 2013·0 cites·1 claims
- 4557US8232031B2Naphthalenetetracarboxylic acid diimide derivative and electrophotographic photoconductor having the sameOHTA MASAFUMI·Filed 2008·Granted Jul 31, 2012·0 cites·11 claims
- 4657US4148638APhotoconductive sensitive material with a trinitro-11-indeno[1,2-b]quinoxaline-11-oneRICOH KK·Filed 1977·Granted Apr 10, 1979·3 cites·22 claims
- 4756US4454212AElectrophotographic photoconductorRICOH KK·Filed 1982·Granted Jun 12, 1984·7 cites·4 claims
- 4852US6090508AOptically anisotropic recording medium and method of recording and erasing information using the sameRICOH KK·Filed 1997·Granted Jul 18, 2000·10 cites·16 claims
- 4951US8207312B2Method of preparing complex-AZO pigment and complex-AZO pigment thereofOHTA MASAFUMI·Filed 2009·Granted Jun 26, 2012·0 cites·10 claims
- 5051US4529678AElectrophotographic photoconductor comprising a dithiol derivativeRICOH KK·Filed 1983·Granted Jul 16, 1985·7 cites·10 claims
Showing the top 50 of 63 patent records by PatentIndex Score.
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