Patents by Inventor Mamoru Senzai

Mamoru Senzai 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 comprising only one control lead per outside line
    Patent number: 4168403
    Abstract: A key telephone system for a predetermined number of outside lines comprises only one control lead shared per outside line by cables connected between a key service unit and key telephone sets, respectively. Each telephone set has manually operable keys for supplying a higher voltage to a relevant control lead while an outside line is selected for an answer or a reanswer to a call present thereon and substituting a lower voltage for the higher voltage when it is desired to hold an answered call.
    Type: Grant
    Filed: February 1, 1978
    Date of Patent: September 18, 1979
    Assignee: Nippon Electric Co., Ltd.
    Inventors: Mamoru Senzai, Tatsuya Kato