Patents by Inventor Yuuji Tsuruga

Yuuji Tsuruga 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).

  • Push-button dial circuit
    Patent number: 4367375
    Abstract: A push-button dial circuit having a low DC resistance and a high output impedance. An oscillator for generating a multi-tone dial signal is connected through a buffer transistor to terminals for coupling the multi-tone dial signal to a subscriber's line. The terminals also supply a DC power source current to the dial circuit. A constant voltage circuit is connected to the oscillator to stabilize the DC current supplied to the oscillator, and a reactance transistor circuit is connected between the terminals and the oscillator for defining a DC supply path from the terminals through the reactance transistor circuit to the oscillator. The reactance transistor circuit includes a transistor having a capacitor and a resistor respectfully connected across the base-emitter path and across the base-collector path of the transistor.
    Type: Grant
    Filed: September 12, 1980
    Date of Patent: January 4, 1983
    Assignees: Iwasaki Tsushinki Kabushiki Kaisha, Nippon Telegraph and Telephone Public Corporation
    Inventors: Yuuji Tsuruga, Akihiro Kobayashi, Makoto Yoshitoshi, Yutaka Nishino