Patents by Inventor Keishiro Hiraga

Keishiro Hiraga 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).

  • Extruded rigid thermoplastic sheet having optically smooth surfaces
    Patent number: 4327149
    Abstract: An extruded rigid thermoplastic sheet having optically smooth surfaces, characterized as exhibiting a degree of optical distortion (.delta.) of from 0.03 to 0.06, is produced by a process wherein a sheet-form extrudate from an extruder is polished by polishing rolls driven via a continuous driving force transmission.
    Type: Grant
    Filed: June 18, 1980
    Date of Patent: April 27, 1982
    Assignee: Asahi Kasei Kogyo Kabushiki Kaisha
    Inventors: Tsuneyuki Katoh, Keishiro Hiraga, Junji Seki, Makoto Suzuki
  • Extruded rigid thermoplastic sheet having optically smooth surfaces
    Patent number: 4247507
    Abstract: An extruded rigid thermoplastic sheet having optically smooth surfaces, characterized as exhibiting a degree of optical distortion (.delta.) of from 0.03 to 0.06, is produced by a process wherein a sheet-form extrudate from an extruder is polished by polishing rolls driven via a continuous driving force transmission.
    Type: Grant
    Filed: January 10, 1979
    Date of Patent: January 27, 1981
    Assignee: Asahi Kasei Kogyo Kabushiki Kaisha
    Inventors: Tsuneyuki Katoh, Keishiro Hiraga, Junji Seki, Makoto Suzuki