Patents by Inventor Douglas A. Messmer

Douglas A. Messmer 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).

  • Educational learning device
    Patent number: 3947978
    Abstract: An answer card and an educational device are disclosed wherein a flexible card has answer selection points on a first side and at least one electrically conductive ink spot on the second side opposite a selection point. The electrically conductive ink spot acts as a switch when the selection point opposite the spot is pressed causing the electrically conductive ink to bridge an open-circuited educational device.
    Type: Grant
    Filed: January 31, 1974
    Date of Patent: April 6, 1976
    Assignee: Techpower, Inc.
    Inventors: Neil M. Clark, Douglas A. Messmer