Patents by Inventor Michihiro Hamada

Michihiro Hamada 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).

  • Digital telephone set having an emergency switching function and communication system having the same
    Patent number: 5142571
    Abstract: A digital telephone set includes a digital telephone circuit and an emergency analog circuit. Normally, the digital telephone circuit is made active so that a handset provided in common therewith is connected to a digital transmission line. In an emergency, the emergency analog circuit is made active instead of the digital telephone circuit so that the handset is connected to an analog transmission line. A dial key pad unit and a speaker are provided in common with the digital telephone circuit and the emergency analog circuit.
    Type: Grant
    Filed: May 21, 1991
    Date of Patent: August 25, 1992
    Assignee: Fujitsu Limited
    Inventors: Yutaka Suzuki, Shigehiko Yazawa, Michihiro Hamada, Yoshiaki Inoue