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. 24, 1985
Filed:
Aug. 17, 1983
Akito Iwamoto, Kamakura, JP;
Hidekazu Sekizawa, Yokohama, JP;
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Abstract
The distance between first and second grating-like structures such as a shadow mask and a faceplate of a color picture tube or the size of pattern elements of the second grating-like structure such as black stripes formed on the inner surface of the faceplate is optically measured. The shadow mask has a periodic pattern of apertures or slots and the faceplate has a periodic pattern of the black stripes. An optical system located between a light source and an assembly of the first and second grating-like structures applies parallel rays of light to the assembly and is arranged to vary an incident angle of the parallel rays to the assembly. A photodetector detects the quantity of light passed through the assembly to produce an electric signal whose amplitude periodically varies with variation in the incident angle of the parallel rays to the assembly. A signal processing unit evaluates the distance between the first and second grating-like structures or the size of pattern elements forming the second grating-like structure on the basis of the electric signal from the photodetector.