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:
Oct. 13, 1987
Filed:
Sep. 30, 1986
Yasuhiko Hara, Tokyo, JP;
Keiya Saito, Yokohama, JP;
Koichi Karasaki, Kanagawa, JP;
Akira Sase, Ibaragi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A method and an apparatus for testing the pattern of a printed circuit board, comprising a stroboscope for emitting intermittent light synchronously with the feed velocity of the printed circuit board; a condenser lens for gathering the intermittent light emitted from the stroboscope and irradiating the gathered light to the printed circuit board; a filter for converting the light of the stroboscope to exciting light; a half mirror for reflecting the exciting light gathered by the condenser lens and converted by the filter, then projecting the reflected light upon the printed circuit board perpendicularly thereto, and passing the excited fluorescent light from the substrate of the printed circuit board; an imaging lens for forming an image of the fluorescent light passed through the half mirror; another filter for eliminating any other light than the fluorescent light out of the entire light passed through the half mirror; a TV camera for picking up the fluorescent image formed by the imaging lens; a memory for storing the preceding-frame pattern video signal obtained from the TV camera with the stroboscope turned on and attenuated by an amount corresponding to the afterimage component; a circuit for subtracting the attenuated stored pattern video signal from the present-frame pattern video signal obtained from the TV camera with the stroboscope turned on; a circuit for generating a reference pattern; and a circuit for producing a negative pattern of the wiring pattern from the output signal of the subtracting circuit and comparing the negative pattern with the reference pattern. In this invention, the image of the printed circuit board set on the table in continuous motion is picked up by the TV camera without any harmful influence of the afterimage so that the printed circuit board can be properly checked to ascertain whether the wiring pattern thereof is normal or not.