Patents by Inventor Jim Cho

Jim Cho 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).

  • DTMF-Code controlled lock device
    Patent number: 4887078
    Abstract: A DTMF-code controlled lock device mainly composed of tow units: a key control unit and a lock-body control unit. The key control unit, adapted to be carried by a user includes a dual-tone multifrequency (DTMF) encoding circuit with a keyboard and an amplifying circuit respectively connected thereto for inputting and outputting an unlocking DTMF code.
    Type: Grant
    Filed: May 5, 1988
    Date of Patent: December 12, 1989
    Inventor: Jim Cho