Patents by Inventor Takao Oikawa

Takao Oikawa 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).

  • Process for producing polymeric piezoelectric elements and the article formed thereby
    Patent number: 3931446
    Abstract: A highly piezoelectric polyvinylidene fluoride element is prepared by treating a polyvinylidene fluoride film having an infrared absorbance ratio D.sub.530 /D.sub.510 of not more than 1.2, namely having a major proportion of .beta.-type crystal structure, at a temperature of at least 40.degree.C but below the melting point of the film while applying to the film a direct current voltage of 200 KV/cm to 1,500 KV/cm. The polyvinylidene fluoride film having a major proportion of .beta.-type crystal structure may be obtained by stretching a fabricated article of polyvinylidene fluoride having a major proportion of .alpha.-type crystal structure under specific conditions.
    Type: Grant
    Filed: March 11, 1974
    Date of Patent: January 6, 1976
    Assignee: Kureha Kagaku Kogyo Kabushiki Kaisha
    Inventors: Naohiro Murayama, Takao Oikawa
  • Medal game device
    Patent number: D596676
    Type: Grant
    Filed: August 5, 2008
    Date of Patent: July 21, 2009
    Assignee: Kabushiki Kaisha Sega
    Inventors: Takao Oikawa, Daisuke Henmi