Patents by Inventor Walter Dorfman

Walter Dorfman 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).

  • Variable reactive force exercise device
    Patent number: 4602373
    Abstract: A variable, reactive force, exercise device which employs a generator with variably positionable commutation brushes and a short circuit load therebetween, to supply a variable opposition force for an operator of the exercise device to overcome.
    Type: Grant
    Filed: September 9, 1983
    Date of Patent: July 22, 1986
    Assignee: Roy S. Robinson
    Inventor: Walter Dorfman
  • Display apparatus for a drum
    Patent number: 4353008
    Abstract: A display apparatus is provided which is responsive to an audio signal to vary the illumination of a light source. The light source has a variable resistance having an initial value when the light source is cold and a larger value when the light source is warm. The display apparatus includes a circuit having a pulse generator which periodically passes pulses of current through the light source to warm the light source prior to illumination of the light source by the modulator sufficient to substantially increase the response time of the light source upon receipt of the audio signal.
    Type: Grant
    Filed: July 7, 1980
    Date of Patent: October 5, 1982
    Assignee: Alfred T. Moffatt
    Inventor: Walter Dorfman