Patents by Inventor Tetsuhiro Umezaki

Tetsuhiro Umezaki 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).

  • Electrophotographic photoreceptor having an azo compound
    Patent number: 4931349
    Abstract: An electrophotographic photoreceptor is provided with a photosensitive layer, which contains an azo compound having in the molecule thereof at least one azo group coupled with a coupler residuum represented by the following general formula (I): ##STR1## wherein X means a residuum capable of condensing with a benzene ring to form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocyclic ring, Y denotes a hydrogen or halogen atom or alkyl or alkoxy group, and n stands for an integer of 0-3.
    Type: Grant
    Filed: December 1, 1987
    Date of Patent: June 5, 1990
    Assignee: Dainichiseika Color & Chemicals Mfg. Co.
    Inventors: Masaru Hasegawa, Osamu Suda, Hisao Kohno, Toshifumi Sekino, Tetsuhiro Umezaki, Norio Tanaka
  • Electrophotographic photoreceptor comprising azo compound and coupler
    Patent number: 4912001
    Abstract: An electrophotographic photoreceptor is provided with a photosensitive layer, which contains an azo compound having in the molecule thereof at least one azo group coupled with a couple residuum represented by the following general formula (I): ##STR1## wherein X means an atomic group necessary for condensing with a benzene ring to form a substituted or unsubstituted aromatic hydrocarbon ring, or substituted or unsubstituted aromatic heterocyclic ring, Y denotes a radical selected from the group consisting of hydrogen, halogen atoms, cyano radicals, and substituted or unsubstituted alkyl, or alkoxy group, and n stands for an integer of 0.about.4, R.sub.1 and R.sub.2 designate, respectively, hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alalkyl, substituted or unsubstituted aromatic hydrocarbon ring or substituted or unsubstituted aromatic heterocyclic ring, and said R.sub.1 and R.sub.2 may be mutually same or different, or may form a ring together with nitrogen atom.
    Type: Grant
    Filed: December 22, 1988
    Date of Patent: March 27, 1990
    Assignee: Dainichi Seika Color & Chemicals Mfg. Co., Ltd.
    Inventors: Hisao Kouno, Hiroaki Saikatsu, Osamu Suda, Tetsuhiro Umezaki, Norio Tanaka, Toshifumi Sekino, Masaru Hasegawa, Yoshio Abe, Shojiro Horiguchi