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. 18, 1986
Filed:
Mar. 07, 1983
Tomohide Watanabe, Yokohama, JP;
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Abstract
Disclosed is an automatic focusing apparatus which comprises an objective disposed in opposition to a substrate with patterns formed thereon, a first line sensor disposed at a first focal point of the focal length of the objective, second and third line sensors which are disposed closer to and farther from the objective by a given distance with respect to second and third focal points of the focal length of the objective, first to third differential circuits for differentiating the output signals from the first to third line sensors, a detecting circuit for detecting a displacement of the substrate from a predetermined proper distance between the objective and the substrate on the basis of the output signals from the first to third differential circuits, and a correcting device for correcting the displacement on the basis of the output signal from the detecting circuit. Thus, a single optical system is used for automatically correcting focus and pattern inspection.