Patents by Inventor Makoto Ookawara

Makoto Ookawara 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).

  • Toner for developing latent electrostatic images
    Patent number: 5102766
    Abstract: A toner for developing latent electronstatic images comprises a coloring agent, a binder resin component and a negative charge controlling agent in an effective amount which is selected from the group consisting of:(i) an aromatic fluoride having formule (I); ##STR1## (ii) an aromatic fluoride having formula (II); ##STR2## (iii) an aromatic fluoride having formula (III); ##STR3## (iv) an aromatic fluoride having formula (IV); and ##STR4## (v) an aromatic fluoride having formula (V). ##STR5## wherein R.sup.1 to R.sup.8, R.sup.f1 and R.sup.f2, n, X and Y are the same as previously defined in the specification.
    Type: Grant
    Filed: March 20, 1990
    Date of Patent: April 7, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Toshiki Nanya, Kimitoshi Yamaguchi, Hiromitsu Kawase, Makoto Ookawara
  • Negative toner for developing latent electrostatic images
    Patent number: 5085965
    Abstract: A negatively chargeable toner for developing latent electrostatic images comprising a coloring agent, a resin component which comprises a homopolymer of a first monomer having formula (I) or a copolymer of the aforementioned first monomer and a second monomer: ##STR1## wherein R.sup.1 represents --H or --CH.sub.3 ; R.sup.2 and R.sup.3 each represent --CN, --COOH or --NO.sub.2 ; R.sup.4 represents --F, --Cl or --Br; and n is an integer of 1 to 10.
    Type: Grant
    Filed: March 20, 1990
    Date of Patent: February 4, 1992
    Assignee: Ricoh Company, Ltd.
    Inventors: Toshiki Nanya, Kimitoshi Yamaguchi, Kazuo Tsubuko, Toshihiko Takahashi, Hiromitsu Kawase, Makoto Ookawara