Patents by Inventor Sijbrand Spannenburg

Sijbrand Spannenburg 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).

  • Support provided with a machine detectable copying security element
    Patent number: 5374976
    Abstract: A support provided with a machine-detectable security element, particularly a copying-security element. The security element comprises a first image perceptible to the human visual system, said first image incorporating a second image that is substantially imperceptible to the human visual system.
    Type: Grant
    Filed: August 12, 1993
    Date of Patent: December 20, 1994
    Assignee: Joh. Enschede en Zonen Grafische Inrichting B.V.
    Inventor: Sijbrand Spannenburg