Photocopying – Projection printing and copying cameras – Focus or magnification control
Patent
1979-12-17
1981-05-19
Wintercorn, Richard A.
Photocopying
Projection printing and copying cameras
Focus or magnification control
354 25, G03B 2752
Patent
active
042681650
ABSTRACT:
The optical elements of a copier are automatically aligned by positioning the elements under the control of signals from an image-dissecting scanner. The scanner, mounted to receive the image normally presented to the photoconductor, examines a master document placed in the position normally occupied by a document to be copied. Optical adjustments are made as a function of the examination of lines on the master document by the scanner. The contrast between a line and its background is maximum when optical elements between the master document and the scanner provide the sharpest focus of the line image to the scanner. Signals from the scanner for a plurality of lines on the master document determine optimum positioning of the optical elements. The scanner determines the apparent spacing between lines, which are a known distance apart on the master document, to position the optical elements for a desired magnification. The positions of selected lines, examined by the scanner, relative to absolute reference points are used to align the master document support for subsequent copying of original documents.
Digitized light-level value samples from the scanner are pushed into a last-in/first-out stack. A value significantly less than the average of the values in the stack indicates that the scanner has found a line. A plurality of scans of the line are then made while adjusting the optical elements. Corresponding light values are pushed into the stack and the average of the values stored in the stack is calculated. If the average is greater than previously calculated averages, a number of additional scans are made to insure that the best focus adjustment has been identified.
REFERENCES:
patent: 3510219 (1970-05-01), Liva
patent: 3623790 (1971-11-01), Buckstad et al.
patent: 3662662 (1972-05-01), Dewan
patent: 3691922 (1972-09-01), Konig et al.
patent: 4171885 (1979-10-01), Kondo
patent: 4175855 (1979-11-01), Turner et al.
patent: 4176928 (1979-12-01), Nakamura et al.
Hauptman Gunter A.
International Business Machines - Corporation
Wintercorn Richard A.
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