Patents by Inventor Shin-ichi Shibata

Shin-ichi Shibata 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).

  • Key telephone system
    Patent number: 4184054
    Abstract: A key telephone system is provided which comprises: a plurality of key telephones; a key service unit; a plurality of transmission paths each including a first transmission cable for transmitting a voice signal between the key telephone and key service unit, a second transmission cable for transmitting a first control signal from the key telephone to the key service unit, and a third transmission cable for transmitting a second control signal from the key service unit to the key telephone; first, second and third transformers of which the primary windings are connected to the key telephone and the secondary windings to the first, second and third transmission cables; and fourth, fifth and sixth transformers of which the primary windings are coupled with the first, second and third transmission cables, respectively, and the secondary windings to the key service unit.
    Type: Grant
    Filed: March 21, 1978
    Date of Patent: January 15, 1980
    Assignee: Tokyo Shibaura Electric Co., Ltd.
    Inventors: Shin-ichi Shibata, Yasuji Sato, Yoshikazu Sano, Takao Yamamoto