Patents by Inventor Yasuyo Ichikawa

Yasuyo Ichikawa 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).

  • Patent number: 5844974
    Abstract: An emergency telephone communications system allows communications during congestion in the event of disaster. The system includes an exchange and telephones connected to the line circuits thereof. The exchange sends a congestion generation signal to a control section to initiate emergency processing when a congestion detecting circuit detects more than a predetermined number of the line circuits in the off-hook state. The control section has a congestion management table listing subscribers and stores not-yet-serviced subscribers when congestion has occurred. The not-yet-serviced subscribers are successively selected from the congestion management table, and calling signals are sent to their telephones. When the subscribers go off-hook within a predetermined time, the control section controls the emergency dial pulse receiver circuit to be ready for reception, and then controls the switch to connect an emergency service trunk to the line circuits to send a tone signal or a voice message.
    Type: Grant
    Filed: May 21, 1996
    Date of Patent: December 1, 1998
    Assignee: NEC Corporation
    Inventor: Yasuyo Ichikawa