Patents by Inventor Earl L. Koppen

Earl L. Koppen 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).

  • Tamperproof reusable bingo card
    Patent number: 4483538
    Abstract: A translucent intermediate sheet having a standard array of bingo numbers is sandwiched between transparent top and bottom sheets. Alterations to the card, such as by a cheater, to permit changing, adding or rearranging bingo numbers can be seen through the sheets.
    Type: Grant
    Filed: March 15, 1983
    Date of Patent: November 20, 1984
    Assignee: Earl L. Koppen
    Inventors: Earl L. Koppen, Douglas E. Winters