Patents by Inventor David T. Willis

David T. Willis 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: 5089806
    Abstract: The apparatus described herein is a chain with a warning sign attached to it, that incorporates an audible alarm signal which is activated when a person moves the chain away from an egress that it is blocking, such as a supermarket check-out lane. The apparatus solves the problem of how to block a check-out lane so as to draw attention to any patron who is exiting the store by way of an unattended check-out lane, yet is a device that can be easily discarded from the egress, in the event of an emergency. The unique sign incorporates circuitry within. In the preferred embodiment, the sign is a sandwich with outer layers that have something appropriate printed on them, such as "ALARMED EXIT--For Emergency Use Only", and the inner, hidden portion contains an audible alarm, a battery, an arming switch and position sensitive contacts for detecting when an unauthorized person tampers with the barrier.
    Type: Grant
    Filed: August 6, 1990
    Date of Patent: February 18, 1992
    Assignee: Carriage Trade Company, Inc.
    Inventors: David T. Willis, Donald Farnsworth