Patents by Inventor Mark J.D. Liddle

Mark J.D. Liddle 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).

  • Keypad
    Patent number: 5936557
    Abstract: In a keypad for an ATM or the like, in addition to mechanical keys (14) which when operated press areas (24) on a pressure sensitive layer (22) against a backing plate (32), and thereby close a corresponding normally-open switch (S), additional areas (26) are arranged as normally-closed switches A, with pressure applied by protrusions (36) on the backing plate (32). If the backing plate is removed, the switches A open, and the change is sensed by a monitoring circuit (48).
    Type: Grant
    Filed: June 25, 1997
    Date of Patent: August 10, 1999
    Assignee: NCR Corporation
    Inventor: Mark J.D. Liddle