Patents by Inventor Erik G. Lindgren

Erik G. Lindgren 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).

  • Optical fire-detector
    Patent number: 4156816
    Abstract: The invention relates to an optical fire-detector in which a radiation-emitting means is arranged to emit a beam of radiation and which has modulator means for the modulation of the beam of radiation in a phase-inverted relationship within a first and a second wavelength band, and a radiation-detecting means is arranged to receive the beam of radiation after it has passed through an intermediate air medium and includes first means for an individual measurement of intensity in the two wavelength bands and second means for the detection of such variations in the measured intensities which are representative for a fire.
    Type: Grant
    Filed: August 4, 1977
    Date of Patent: May 29, 1979
    Assignee: Telefonaktiebolaget L M Ericsson
    Inventor: Erik G. Lindgren