Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1982-09-13
1985-05-21
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356375, G01B 1100
Patent
active
045188629
ABSTRACT:
An apparatus for determining the position of a sheet when the sheet is placed on a support having at least two spaced apart CCD linear image sensors recessed in the sheet support and partially covered by the edge portions of the sheet. The CCDs operate as line cameras, and are scanned to generate signals correlated with the points of intersection of the sheet edges and the axes of the image sensors. Preferably the apparatus has circuitry for storing calibration values of the CCD signals obtained when the image sensors are not covered by the sheet, circuitry for storing corresponding scanning signal values when the image sensors are covered by the sheet, circuitry for comparing corresponding calibration and scanning values for obtaining difference values, and circuitry for detecting maxima in the gradient of the difference values for adjacent image points to find the locations of the points of intersection of the sheet edges and the axes of image sensors. These locations are used by software driving an X-Y plotter head or by a sheet positioning mechanism to correct for variations in sheet position.
REFERENCES:
patent: 3621266 (1971-11-01), Akuta et al.
patent: 4074131 (1978-02-01), Schwebel
patent: 4277176 (1981-07-01), Grosvernier
patent: 4367045 (1983-01-01), Grosvernier
Brochure "CCD Analog VLSI-Technology of the 80's" published by Electronic 2000 Vertriebs GmbH Neumarkter Str. 71 presented at the LASER Exposition in Munich on Jun. 2, 1981, pp. 5-6, 86-89, 126.30-126.32.
M.A.N.--Roland Druckmaschinen Aktiengesellschaft
Westin Edward P.
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