Patents by Inventor Piet M. J. Extra

Piet M. J. Extra 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).

  • Patent number: 4265997
    Abstract: In a system for developing electrostatic images on a moving photoconductive support by contact with a brush of two-component developer powder carried on a moving surface, in which the toner content of the powder is controlled in response to optical sensings of the reflectance of the brush at a location just beyond the developing zone, objectionable fluctuations of the toner concentration are avoided by shaping the developer brush to a constant layer thickness, for instance by reducing its thickness to about 0.5 to 0.6 mm, as the brush is being transported from the developing zone so that the sensings of the reflectance will occur at a constant distance from the brush. As an aid for adjusting or checking the operation of the toner control system, a reference surface having the same reflectance as a developer layer of the prescribed thickness and toner concentration is inserted in place of the brush at the location where reflectance is sensed.
    Type: Grant
    Filed: August 9, 1979
    Date of Patent: May 5, 1981
    Assignee: Oce-Nederland B.V.
    Inventors: Piet M. J. Extra, Taco H. J. van den Honert, Jacobus J. van Lieshout
  • Patent number: 4112870
    Abstract: An apparatus for developing electrostatic charge images on a moving support, e.g. on a photoconductive belt, by a developing powder composed of toner particles and magnetizable carrier particles, which powder is transported by a rotating magnetic roller from a reservoir through a developing zone where a magnetic roller from a reservoir through a developing zone where a magnetic brush is formed between the roller and the support, is provided with means for preventing variations of the quality of the developed images by supplying more developing powder to the brush than the roller transports through the developing zone. The excess powder flows away over a partition into a trough containing a rotor, to be remixed with powder from the reservoir and propelled by the rotor into a narrowing passage defined between the partition and the side of the magnetic roller that moves toward the support.
    Type: Grant
    Filed: April 26, 1977
    Date of Patent: September 12, 1978
    Assignee: Oce-van der Grinten N.V.
    Inventors: Piet M. J. Extra, Lambertus R. J. M. Smeets, Adrianus W. M. Van Bavel, Jacobus J. Van Lieshout, Albert T. Deckers