Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1986-09-30
1987-10-13
Britton, Howard W.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
382 8, H04N 718
Patent
active
047002255
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.
REFERENCES:
patent: 4148065 (1979-04-01), Nakagawa
patent: 4152723 (1979-05-01), McMahon
patent: 4556903 (1985-12-01), Blitchington
Hara Yasuhiko
Karasaki Koichi
Saito Keiya
Sase Akira
Britton Howard W.
Hitachi , Ltd.
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