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:
Apr. 15, 1986
Filed:
Feb. 22, 1985
Heinz Baier, Sindelfingen, DE;
Michael Kallmeyer, Boeblingen, DE;
Peter Koepp, Weil im Schoenbuch, DE;
Erwin Pfeffer, Holzgerlingen, DE;
Martin Schneiderhan, Stuttgart, DE;
International Business Machines Corporation, Armonk, NY (US);
Abstract
In this circuit, video signals with a continuously increasing or decreasing amplitude are applied to the signal input of a threshold difference comparator at whose reference inputs selectively determined high and low threshold signals are applied. The output of the threshold difference comparator is applied at the first input of a threshold AND gate having a second input connected to a clock. The output of the threshold AND gate supplies a clock pulse sequence which has a duration corresponding with the time during which the input video signal has an amplitude which continuously increases or decreases from one of the threshold reference amplitudes to the other. The clock pulse sequences contained in successive measuring intervals have their respective pulses counted by a counter, and are stored in a buffer. A measurement series is performed corresponding to different focus settings, optimum focus adjustment being achieved when a minimum count of clock pulses in a clock pulse sequence is obtained.