Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1983-12-20
1985-12-03
Britton, Howard W.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358101, 358107, 358294, 356237, 250224, H04N 718, H04N 700, H04N 102
Patent
active
045569037
ABSTRACT:
A system for generating a substantially-continuous stream of binary signals representative of the presence of copper on the surface of a fluorescent substrate of a board. A beam is swept by mirror facets of a rotating mirror drum along a path on the board. When the beam strikes copper it is merely relected. When the beam strikes the substrate, a fluorescence is produced. The resultant light is gathered by cylindrical lenses and fiber optic bundles. The color of the light is blocked by filters and the fluorescence color energizes photomultiplier tubes. A threshold setting and sensing circuit senses the output of the photomultiplier tubes and controls their bias voltage to produce a constant level of output from fluorescence and then produces a stream of binary signals that are representative of the presence/absence of copper on the surface of the board. The swept beam is split to send a portion of its energy through an optical grating. The intermittent light passing through the optical grating is gathered by a fiber optic bundle and is sensed by a photomultiplier tube. The output of the photomultiplier tube is doubled in frequency and used to sample and store the binary signals in the memory of a scanning converter. The binary signals arrive in short bursts of higher-frequency signals separated by periods of absence of binary data. The binary signals stored in the scanning converter are then read out substantially continously for subsequent processing at a lower frequency.
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Printed Circuit World Expo '80 Proceedings (Nov., 1980), "Automatic Optical Inspection of Printed Wiring Boards", p. 44.
Automatic Inspection System for Printed Circuit Photomasks, a product circular by Fujitsu, Ltd. (published by early 1983).
Restrick, R. C. "An Automatic Optical Printed Circuit Inspection System", Solid State Imaging Devices, SPIE, vol. 116, Bellingham, Wash., Aug. 23-24, 1977, pp. 76-81.
Blitchington Frank H.
Haught David E.
AT&T - Technologies, Inc.
Britton Howard W.
Dosse W. G.
Peng John K.
Rosen S. I.
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