Patents by Inventor Atsuko Niwa

Atsuko Niwa 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).

  • Patent number: 6639925
    Abstract: An information processor of a high reliability and a high recording density, and a blue color, blue-violet color and violet color based semiconductor light emitting device operable at a low threshold current density, used for the same, are provided. An optical information processor of a high reliability and a high recording density enables a moving picture, such as a high-definition television picture, to be recorded and reproduced satisfactorily. A barrier layer in a quantum-well active layer of a semiconductor light emitting device is doped with n-type impurities at a high density. Alternatively, the face orientation of a quantum-well active layer of a semiconductor light emitting device is a plane inclined from the (0001) plane, whereby the threshold current value of the semiconductor light emitting device can be decreased. The semiconductor light emitting device is typified by a gallium nitride based compound semiconductor laser device.
    Type: Grant
    Filed: September 28, 2001
    Date of Patent: October 28, 2003
    Assignee: Hitachi, Inc.
    Inventors: Atsuko Niwa, Tsukuru Ohtoshi, Takao Kuroda, Makoto Okai, Takeshi Shimano
  • Patent number: 6542526
    Abstract: Provided are highly reliable information processing equipment enabling a high recording density, and a blue color, blue-violet color and violet color based semiconductor light emitting device operable at a low threshold current density, which device is suitable for the information processing equipment. According to the present invention, there can be realized highly reliable optical information processing equipment enabling high recording density, which is capable of sufficiently recording or reproducing a dynamic image in or from a high-definition TV. An n-type impurity is doped in a barrier layer of a quantum-well active layer of a semiconductor light emitting device at a high density. Alternatively, the oriented plane of a quantum-well active layer of a semiconductor light emitting device is inclined from the (0001) plane, whereby the threshold current value of the semiconductor light emitting device can be reduced.
    Type: Grant
    Filed: April 26, 1999
    Date of Patent: April 1, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Atsuko Niwa, Tsukuru Ohtoshi, Takao Kuroda, Makoto Okai, Takeshi Shimano
  • Publication number: 20020031153
    Abstract: An information processor of a high reliability and a high recording density, and a blue color, blue-violet color and violet color based semiconductor light emitting device operable at a low threshold current density, used for the same, are provided. An optical information processor of a high reliability and a high recording density enables a moving picture, such as a high-definition television picture, to be recorded and reproduced satisfactorily. A barrier layer in a quantum-well active layer of a semiconductor light emitting device is doped with n-type impurities at a high density. Alternatively, the face orientation of a quantum-well active layer of a semiconductor light emitting device is a plane inclined from the (0001) plane, whereby the threshold current value of the semiconductor light emitting device can be decreased. The semiconductor light emitting device is typified by a gallium nitride based compound semiconductor laser device.
    Type: Application
    Filed: September 28, 2001
    Publication date: March 14, 2002
    Inventors: Atsuko Niwa, Tsukuru Ohtoshi, Takao Kuroda, Makoto Okai, Takeshi Shimano