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:
Jul. 06, 1993
Filed:
Sep. 18, 1990
Mitsuyoshi Koizumi, Yokohama, JP;
Yoshimasa Ohshima, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
Disclosed herein are method of and apparatus for detecting a foreign substance on an object by illuminating said object, detecting via an optical system light reflected from said object and detecting said foreign substance in distinction from a background. The object is exposed to first illumination such that light reflected from said background is suppressed but light reflected from said foreign substance is highlighted relative to the light reflected from said background. The light reflected from said object as a result of said first illumination is detected, thereby obtaining a first detection signal. The object is exposed to second illumination such that light reflected from said background is free from suppression relative to the light reflected from said substance as a result of said second illumination. The light reflected from said object as a result of said second illumination is detected, thereby obtaining a second detection signal. Foreign-substance-highlighting processing is performed on said first detection signal by using said second detection signal, whereby said substance is detected.