Patents by Inventor Hiroyasu Yashima

Hiroyasu Yashima 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).

  • Red emitting phosphor for cathode ray tube
    Patent number: 6268691
    Abstract: A red emitting phosphor comprises a yttrium oxysulfide phosphor as a base material. A red emitting phosphor of medium particle size type has such a particle size distribution that a content of a component of a particle diameter of less than 4.0 &mgr;m is 15% or less, that of a component of a particle diameter of 4.0 &mgr;m or more and less than 8.0 &mgr;m is 75% or more, and that of a component of a particle diameter of 8.0 &mgr;m or more is 10% or less. A red emitting phosphor of larger particle size type has such a particle size distribution that the content of a component of a particle diameter of less than 5.04 &mgr;m is 20% or less, that of a component of a particle diameter of 5.04 &mgr;m or more and less than 10.079 &mgr;m is 70% or more, and that of a component of a particle diameter of 10.079 &mgr;m or more is 10% or less. Phosphor layers employing these red emitting phosphors are excellent in denseness. Accordingly, a cathode ray tube of high contrast and high quality can be provided.
    Type: Grant
    Filed: August 23, 1999
    Date of Patent: July 31, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hirofumi Takemura, Satoshi Sugano, Hiroyasu Yashima, Yohe Shimizu, Tsuyoshi Oyaizu, Akira Mikami