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:
Aug. 18, 1998
Filed:
Feb. 12, 1997
Toyoki Kanzaki, Miyanohigashi-machi, JP;
Dainichiro Kinoshita, Miyanohigashi-machi, JP;
Horiba, Ltd., Kyoto, JP;
Abstract
A signal processing method and an improved defect detecting apparatus which scans a circuit substrate with a laser beam is provided to enable a distinction between a circuit pattern signal and a defect signal. A laser beam is scanned across the surface of a substrate with the reflected light picked up by a photodetector. The photodetector provides an output signal that can comprise both a pattern signal and a defect signal. This output signal is applied to a first signal processing line having a low-pass filter characteristic and a second signal processing line without a low-pass filter characteristic. The signals can be appropriately amplified and/or delayed and are finally submitted to a subtraction circuit so that the resulting output signal enables a ready determination of a defect apart from the existence of any pattern signal.