Patents by Inventor Masafumi Ohta

Masafumi Ohta has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20090005546
    Abstract: An azo compound having the following formula (I): A(E)n ??(I) wherein A represents a residue of an azo compound, bonded with n pieces of E group through one or more heteroatom being N or O and forming a part of the residue A; E independently represents a hydrogen atom or —C(?O)—O—R1 wherein R1 represents a substituted or an unsubstituted alkyl group having 4 to 10 carbon atoms, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group or an aralkyl group; and n represents an integer of from 1 to 10.
    Type: Application
    Filed: June 26, 2008
    Publication date: January 1, 2009
    Applicant: RICOH COMPANY, LTD.
    Inventor: Masafumi Ohta
  • Publication number: 20070269729
    Abstract: An electrophotographic photoreceptor is provided, including an electroconductive substrate and a photosensitive layer located overlying the electroconductive substrate, wherein an outermost layer of the electrophotographic photoreceptor includes a resin including a graft copolymer in which a monomer having a polar group is graft polymerized to a polycarbonate resin, a polyarylate resin, or a copolymer thereof, and a filler; along with an image forming apparatus and a process cartridge using the electrophotographic photoreceptor.
    Type: Application
    Filed: May 18, 2007
    Publication date: November 22, 2007
    Inventors: Hiroshi Ikuno, Masafumi Ohta, Tomoyuki Shimada, Yuuji Tanaka, Hongguo Li
  • Patent number: 6316577
    Abstract: An electrophotographic photoconductor includes an electroconductive support, and a photoconductive layer formed thereon containing as an effective component an aromatic polycarbonate resin having a structural unit of formula (I), two structural units of formulae (I) and (II), or a repeat unit of formula (III): wherein Ar1 to Ar7, Y, X, and n are as specified in the specification.
    Type: Grant
    Filed: January 10, 2000
    Date of Patent: November 13, 2001
    Assignee: Hodogaya Chemical Co., Ltd.
    Inventors: Tomoyuki Shimada, Masaomi Sasaki, Masafumi Ohta, Akihiro Imai, Mitsutoshi Anzai, Tamotsu Aruga, Kazukiyo Nagai, Katsuhiro Morooka
  • Patent number: 6090508
    Abstract: An optically anisotropic recording medium and a method of recording and erasing method using the recording medium are disclosed, which comprises the steps of applying heat or light to the recording medium which comprises a recording layer made of optically anisotropic organic thin-film-shaped crystals to raise the temperature of an organic material or which comprises the optically anisotropic organic thin-film-shaped crystals to a recording temperature at which the crystals are fused, performing partial changing of the crystalline state of the crystals by rapidly cooling the recording layer, thereby recording information in the recording layer; and heating the recording layer to an erasing temperature which is lower than the recording temperature, at which the crystals are not fused, but the molecules thereof can be thermally moved.
    Type: Grant
    Filed: August 27, 1997
    Date of Patent: July 18, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Kyoji Tsutsui, Akio Kojima, Masafumi Ohta, Ryohei Miyake
  • Patent number: 6027846
    Abstract: An electrophotographic photoconductor includes an electroconductive support, and a photoconductive layer formed thereon containing as an effective component an aromatic polycarbonate resin having a structural unit of formula (I), two structural units of formulae (I) and (II), or a repeat unit of formula (III): ##STR1## wherein Ar.sup.1 to Ar.sup.7, Y, X, and n are as specified in the specification.
    Type: Grant
    Filed: June 28, 1996
    Date of Patent: February 22, 2000
    Assignees: Ricoh Company, Ltd., Hodogaya Chemical Co., Ltd.
    Inventors: Tomoyuki Shimada, Masaomi Sasaki, Masafumi Ohta, Akihiro Imai, Mitsutoshi Anzai, Tamotsu Aruga, Kazukiyo Nagai, Katsuhiro Morooka
  • Patent number: 5830980
    Abstract: An electrophotographic photoconductor includes an electroconductive support, and a photoconductive layer formed thereon, containing a novel aromatic polycarbonate resin having a repeat unit of formula (I): ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 each is an alkyl group which may have a substituent, or a halogen atom; R.sup.4 is a hydrogen atom, or an alkyl group which may have a substituent; Ar.sup.1 and Ar.sup.2 each is an aromatic hydrocarbon group which may have a substituent; l, m and n each is an integer of 0 to 4; k is an integer of 5 to 5,000; and X is a bivalent aliphatic group, a bivalent cyclic aliphatic group, or ##STR2## in which R.sup.5 and R.sup.6 each is an alkyl group which may have a substituent, a halogen atom, or an aromatic hydrocarbon group; p and q each is an integer of 0 to 4; and r is 0 or 1, and when r is 1, Y is a straight-chain, branched or cyclic alkylene group having 1 to 12 carbon atoms, --O--, --S--, --SO--, --SO.sub.2 --, or --C(O)--.
    Type: Grant
    Filed: October 23, 1997
    Date of Patent: November 3, 1998
    Assignees: Ricoh Company, Ltd., Hodogaya Chemical Co., Ltd.
    Inventors: Mitsutoshi Anzai, Akihiro Imai, Masaomi Sasaki, Hiroshi Tamura, Tomoyuki Shimada, Tetsuro Suzuki, Masafumi Ohta
  • Patent number: 5747204
    Abstract: An electrophotographic photoconductor includes an electroconductive support, and a photoconductive layer formed thereon, containing a novel aromatic polycarbonate resin having a repeat unit of formula (I): ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 each is an alkyl group which may have a substituent, or a halogen atom; R.sup.4 is a hydrogen atom, or an alkyl group which may have a substituent; Ar.sup.1 and Ar.sup.2 each is an aromatic hydrocarbon group which may have a substituent; l, m and n each is an integer of 0 to 4; k is an integer of 5 to 5,000; and X is a bivalent aliphatic group, a bivalent cyclic aliphatic group, or ##STR2## in which R.sup.5 and R.sup.6 each is an alkyl group which may have a substituent, a halogen atom, or an aromatic hydrocarbon group; p and q each is an integer of 0 to 4; and r is 0 or 1, and when r is 1, Y is a straight-chain, branched or cyclic alkylene group having 1 to 12 carbon atoms, --O--, --S--, --SO--, --SO.sub.2 --, or --C(O)--.
    Type: Grant
    Filed: June 18, 1996
    Date of Patent: May 5, 1998
    Assignees: Ricoh Company, Ltd., Hodogaya Chemical Co., Ltd.
    Inventors: Mitsutoshi Anzai, Akihiro Imai, Masaomi Sasaki, Hiroshi Tamura, Tomoyuki Shimada, Tetsuro Suzuki, Masafumi Ohta
  • Patent number: 5672756
    Abstract: An electrophotographic photoconductor includes an electroconductive substrate, and a photoconductive layer formed thereon containing at least one tertiary amine compound of formula (I) as an effective component: ##STR1## wherein Ar.sup.1 and Ar.sup.3 each is an aryl group which may have a substituent; Ar.sup.2 is a bivalent group of a carboxylic aromatic compound or a bivalent group of a heterocyclic compound; R.sup.1 is a hydrogen atom, an alkyl group which may have a substituent or an alkoxy group which may have a substituent; and R.sup.2 is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent. A novel triphenylamine compound for use in the electrophotographic photoconductor is provided.
    Type: Grant
    Filed: July 25, 1996
    Date of Patent: September 30, 1997
    Assignees: Ricoh Company, Ltd., Hodogaya Chemical Co., Ltd.
    Inventors: Tomoyuki Shimada, Masaomi Sasaki, Tamotsu Aruga, Masafumi Ohta, Mitsutoshi Anzai, Akihiro Imai
  • Patent number: 5656401
    Abstract: An electroluminescent device is composed of a negative electrode, a positive electrode, and an organic compound layer which is interposed between the negative electrode and the positive electrode and includes at least one oxadiazole compound with a plurality of aryl oxadiazole structures. Novel oxadiazole compounds for use in the electroluminescent device and a method of producing the oxadiazole compounds are disclosed.
    Type: Grant
    Filed: October 12, 1994
    Date of Patent: August 12, 1997
    Assignee: Ricoh Company, Ltd.
    Inventors: Masafumi Ohta, Yohta Sakon, Toshihiko Takahashi, Chihaya Adachi, Kazukiyo Nagai
  • Patent number: 5631404
    Abstract: An electrophotographic photoconductor includes an electroconductive support and a photoconductive layer formed thereon containing a diamine compound represented by formula (I): ##STR1## wherein R.sup.1, R.sup.2, and R.sup.3 each is independently a substituted or unsubstituted alkyl group or aryl group; R.sup.4 is hydrogen, an alkyl group or an alkoxyl group; n is an integer of 1 to 3; and ##STR2## is a substituted or unsubstituted bivalent arylene group or a bivalent heterocyclic group. This diamine compound is useful as a photoconductive material for electrophotographic photoconductors.
    Type: Grant
    Filed: June 1, 1995
    Date of Patent: May 20, 1997
    Assignees: Ricoh Company, Ltd., Hodogaya Chemical Co., Ltd.
    Inventors: Mitsutoshi Anzai, Yasuo Murakami, Atsushi Takesue, Masaomi Sasaki, Tomoyuki Shimada, Tamotsu Aruga, Masafumi Ohta
  • Patent number: 5610309
    Abstract: An electroluminescent device is composed of a negative electrode, a positive electrode, and an organic compound layer which is interposed between the negative electrode and the positive electrode and includes at least one oxadiazole compound with a plurality of aryl oxadiazole structures. Novel oxadiazole compounds for use in the electroluminescent device and a method of producing the oxadiazole compounds are disclosed.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: March 11, 1997
    Assignee: Ricoh Company, Ltd.
    Inventors: Masafumi Ohta, Yohta Sakon, Toshihiko Takahashi, Chihaya Adachi, Kazukiyo Nagai
  • Patent number: 5604065
    Abstract: An electrophotographic photoconductor includes an electroconductive substrate, and a photoconductive layer formed thereon containing at least one tertiary amine compound of formula (I) as an effective component: ##STR1## wherein Ar.sup.1 and Ar.sup.3 each is an aryl group which may have a substituent; Ar.sup.2 is a bivalent group of a carbocyclic aromatic compound or a bivalent group of a heterocyclic compound; R.sup.1 is a hydrogen atom, an alkyl group which may have a substituent or an alkoxyl group which may have a substituent; and R.sup.2 is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent. A novel triphenylamine compound for use in the electrophotographic photoconductor is provided.
    Type: Grant
    Filed: September 14, 1995
    Date of Patent: February 18, 1997
    Assignees: Ricoh Company, Ltd., Hodogaya Chemical Co., Ltd.
    Inventors: Tomoyuki Shimada, Masaomi Sasaki, Tamotsu Aruga, Masafumi Ohta, Mitsutoshi Anzai, Akihiro Imai
  • Patent number: 5597925
    Abstract: An electroluminescent device is composed of a negative electrode, a positive electrode, and an organic compound layer which is interposed between the negative electrode and the positive electrode and includes at least one oxadiazole compound with a plurality of aryl oxadiazole structures. Novel oxadiazole compounds for use in the electroluminescent device and a method of producing the oxadiazole compounds are disclosed.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: January 28, 1997
    Assignee: Ricoh Company, Ltd.
    Inventors: Masafumi Ohta, Yohta Sakon, Toshihiko Takahashi, Chihaya Adachi, Kazukiyo Nagai
  • Patent number: 5492784
    Abstract: A positively-chargeable single-layered type organic electrophotographic photoconductor composed of an electroconductive support and an organic single-layered photoconductive layer containing a charge generating material, an organic positive hole transporting material and an organic acceptor compound which are dispersed in a matrix binder agent, with the relationship of the oxidation potential (E.sub.ox) of the charge generating material.ltoreq.the oxidation potential (E.sub.ox) of the organic positive hole transporting material being satisfied.
    Type: Grant
    Filed: August 6, 1993
    Date of Patent: February 20, 1996
    Assignee: Ricoh Company, Ltd.
    Inventors: Masao Yoshikawa, Masayuki Shoshi, Tetsuro Suzuki, Masakatsu Shimoda, Kaoru Teramura, Megumi Kawahara, Akio Kojima, Masaomi Sasaki, Masafumi Ohta
  • Patent number: 5489495
    Abstract: An electrophotographic photoconductor includes an electroconductive support and a photoconductive layer formed thereon containing a diamine compound represented by formula (I): ##STR1## wherein R.sup.1, R.sup.2, and R.sup.3 each is independently a substituted or unsubstituted alkyl group or aryl group; R.sup.4 is hydrogen, an alkyl group or an alkoxyl group; n is an integer of 1 to 3; and ##STR2## is a substituted or unsubstituted bivalent arylene group or a bivalent heterocyclic group. This diamine compound is useful as a photoconductive material for electrophotographic photoconductors.
    Type: Grant
    Filed: October 20, 1994
    Date of Patent: February 6, 1996
    Assignees: Richoh Company, Ltd., Hodogaya Chemical Co., Ltd.
    Inventors: Mitsutoshi Anzai, Yasuo Murakami, Atsushi Takesue, Masaomi Sasaki, Tomoyuki Shimada, Tamotsu Aruga, Masafumi Ohta
  • Patent number: 5420288
    Abstract: An electroluminescent device is composed of a negative electrode, a positive electrode, and an organic compound layer which is interposed between the negative electrode and the positive electrode and includes at least one oxadiazole compound with a plurality of aryl oxadiazole structures. Novel oxadiazole compounds for use in the electroluminescent device and a method of producing the oxadiazole compounds are disclosed.
    Type: Grant
    Filed: April 14, 1993
    Date of Patent: May 30, 1995
    Assignee: Ricoh Company, Ltd.
    Inventors: Masafumi Ohta, Yohta Sakon, Toshihiko Takahashi, Chihaya Adachi, Kazukiyo Nagai
  • Patent number: 5153073
    Abstract: Disclosed herein is an electroluminescent device comprising an anode and a cathode and one or plurality of organic compound layer sandwiched therebetween, at least one of the organic compound layers being composed of an organic compound represented by the general formula (I): ##STR1## (wherein A.sup.1 and A.sup.2 each represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group which may be identical or different with each other, Ar represents a substituted or unsubstituted pyrenyl group and n represents 1 or 2).
    Type: Grant
    Filed: June 28, 1991
    Date of Patent: October 6, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Teruyuki Ohnuma, Tomoyuki Shimada, Masafumi Ohta, Fumio Kawamura, Yohta Sakon, Toshihiko Takahashi
  • Patent number: 5118986
    Abstract: An electroluminescent device having:an anode and a cathode; andat least two organic compound layers sandwiched between said two electrodes,at least one of said organic compound layers being a hole transporting layer containing a compound represented by the following general formula (I) ##STR1## wherein R.sup.1 represents hydrogen atom, a lower alkyl group, a lower alkoxy groups, a halogen or a nitro group, A represents ##STR2## (wherein R.sup.2 represents a lower alkyl group, a substituted or non-substituted aryl group or an aralkyl group, and R.sup.3 represents a lower alkyl group.
    Type: Grant
    Filed: June 21, 1990
    Date of Patent: June 2, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Teruyuki Ohnuma, Fumio Kawamura, Masafumi Ohta, Yohta Sakon, Toshihiko Takahashi, Mitsuru Hashimoto
  • Patent number: 5093210
    Abstract: Disclosed herein is an electroluminescent device having a luminescent layer comprising a luminescent material, which is capable of directly converting the energy of electric field applied thereto into a light energy and capable of providing a large surface-area luminescence.
    Type: Grant
    Filed: June 28, 1990
    Date of Patent: March 3, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Masafumi Ohta, Teruyuki Ohnuma, Fumio Kawamura, Yohta Sakon, Toshihiko Takahashi
  • Patent number: 4992109
    Abstract: A photoelectric conversion element has a front electrode, a rear electrode and a photo-activatable layer sandwiched between these electrodes. The photo-activatable layer contains a compound selected from a group consisting of a triphenylamine compound, a diaminocarbazole compound, an oxazole compound, a thiazole compound, and 1,3-dithiol compound. The compound contained in the photo-activatable layer improves photoelectric conversion efficiency.
    Type: Grant
    Filed: December 13, 1989
    Date of Patent: February 12, 1991
    Assignee: Ricoh Company, Ltd.
    Inventors: Masao Yoshikawa, Tetsuro Suzuki, Akio Kojima, Masayuki Shoshi, Masafumi Ohta