Fritz Albrecht

US Patent:

40054438, Jan 25, 1977

Filed:

Sep 11, 1975

Appl. No.:

5/612295

Inventors:

Fritz Albrecht - Brevard NC

International Classification:

G03B 708

US Classification:

354 25

Abstract:

A device for automatically focusing an image in an optical system such as a camera wherein a photosensitive array having a plurality of discrete sites is positioned in the focal plane of the optical system to dissect the image into segments and determine the light intensity at each segment. Means are interposed in the focal plane to vary the focus of the image, the illumination of the photosensitive array being dependent on the degree of focus of the image. The discrete sites have a charge produced thereon depending on the degree of illumination. Address means scan the photosensitive array and read out the charges on the discrete sites to form a pulse train. Discrimination means are connected to the address means to determine when the frequency of the pulse train is maximized to indicate sharp focusing of the image, as the focus of the image is varied.