Patents by Inventor Frank C. Tong

Frank C. Tong 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).

  • Mail box signalling mechanism
    Patent number: 4063681
    Abstract: An improved mail box signalling mechanism that may be quickly and easily installed on conventional rural mail boxes provides a flag that is automatically displayed when mail is deposited in the mail box by the postman to give the box holder a positive visual indication that mail has in fact been delivered.
    Type: Grant
    Filed: May 6, 1976
    Date of Patent: December 20, 1977
    Inventor: Frank C. Tong