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:
Mar. 14, 1989
Filed:
Mar. 11, 1988
Ernest P Riedel, Murrysville, PA (US);
Robert A Boenning, Timonium, MD (US);
Westinghouse Electric Corp., Pittsburgh, PA (US);
Abstract
An apparatus for optically detecting electronic circuit malfunctions includes a light transmitting plate member which is adapted to be positioned adjacent to a plurality of individual electronic circuit elements positioned on a printed circuit board. First and second polarizing filters are positioned adjacent to opposing edges of the light transmitting plate. As the individual electronic circuit elements positioned on the circuit board are operated, the nonuniform heating of the light transmitting plate by the circuit elements produces mechanical stresses within the plate. As monochromatic or white light is passed through the pair of polarizing filters and the light transmitting plate, a light/dark striated pattern of light is produced on the surface of the second polarizing filter. By recording the pattern of a properly operating printed circuit board, a reference pattern may be obtained. Subsequent patterns of light are compared to the reference pattern in order to detect differences between patterns. These differences indicate a change in the temperature of an electronic circuit element with respect to its proper operating temperature, and further indicates a possible malfunction of that individual circuit element.