Patents by Inventor Tetsuo Yagyu

Tetsuo Yagyu 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).

  • Ringtrip judging circuit
    Patent number: 5684874
    Abstract: A ringtrip judging circuit includes a single comparator for comparing a detection value of a ringing current with a threshold value and for outputting the result of the comparison, a threshold value control circuit for supplying the threshold value to the comparator, and a judging circuit for judging ringtrip based on the output of the comparator. During a prescribed period after ringing signal transmission, the threshold value control circuit changes the threshold value in a steplike manner in accordance with the result of the comparison, thereby determining a threshold value greater than a peak value during the prescribed period, and based on it, determines a threshold value for ringtrip judgement and supplies it to the comparator.
    Type: Grant
    Filed: November 13, 1995
    Date of Patent: November 4, 1997
    Assignee: Fujitsu Limited
    Inventors: Tetsuo Yagyu, Takahiro Watai, Hirokazu Tanaka, Tetsuji Funaki, Kunihiko Gotoh