Patents by Inventor Ludger Bertels

Ludger Bertels 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).

  • Cassette for holding a roll
    Patent number: 5046677
    Abstract: The present invention relates to a light-tight roll-film cassette for holding and dispensing rolls of light sensitive material, having brake means exerting a retarding force on the core of the roll. This brake means consist of a resilient tongue cooperating with the cylindric bearings.
    Type: Grant
    Filed: May 1, 1989
    Date of Patent: September 10, 1991
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Erhard Loewe, Ludger Bertels
  • Lightproof cassette
    Patent number: 4889292
    Abstract: The present invention relates to a light-tight roll-film cassette for holding and dispensing light sensitive material, having lips forming a dispensing slot for the material drawn from the roll, these lips being mechanically enforced by ribs. The cassette has the advantage of improved light-tightness at the dispensing slot without increasing the dispensing forces.
    Type: Grant
    Filed: May 1, 1989
    Date of Patent: December 26, 1989
    Assignee: E. I. Du Pont De Nemours and Company
    Inventors: Erhard Loewe, Ludger Bertels