The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 05, 1978
Filed:
Aug. 01, 1977
George W Smith, Birmingham, MI (US);
Michael Kaplit, Birmingham, MI (US);
Daniel B Hayden, Port Huron, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A nematic liquid crystal display device exhibits dielectric anisotropy when the device is in a normal operating temperature range. By placing electrodes on either side of the layer of liquid crystal material and applying across the material an electric field insufficient to change the molecular orientation in the material, the capacitance and therefore the dielectric constant of the material is measured. A similar measurement of dielectric constant is made with a strong electric field applied across the material such that the molecules are re-oriented unless the device is so cold that the molecular change cannot occur and the device is inoperative as a display. By comparing the dielectric constants, it is determined whether the device is at a suitable operating temperature and a heater for the device is controlled accordingly.