GB1448424A - Focus detecting apparatus - Google Patents

Abstract

1448424 Automatic focusing HONEYWELL Inc 8 July 1974 [9 July 1973] 30125/74 Heading H4D In an automatic focusing system, images of the scene to be focused are produced on linear arrays 1, 3 of detectors 5, 7, 9, 11 and 13, 15, 17, 19 by respective lenses 27, 28. Lens 29 is movable in its plane to cause the image produced thereby to move over the array 3 until the image portions incident on corresponding detectors of the arrays (e.g. 5 and 13) are equal. By triangulation considerations the position of the lens 29 then indicates the range of the scene and can be used to control the main focusing lens 43 of the camera. The detectors may be photoresistive with corresponding detectorse.g. 5 and 13-being connected between +V and -V sources, the interconnection points, e.g. 31-supplying an indication, e.g. A-of the difference of illumination of the detectors. The interconnection points 31, 33, 35, 37 are coupled to a signal processor 39 which supplies a control signal F for the lesses 29 and 43. The signal processor 39 may perform the functions, /A/+/B/+/C/+/D/ or (A)<SP>2</SP>+(B)<SP>2</SP>+(C)<SP>2</SP>+(D)<SP>2</SP> or, Fig. 7 (not shown), may sum the full wave rectified A, B, C, D signals or, Fig. 8 (not shown), may rectify and sum the cross-correlation products of A x B, B x C, C x D. The detectors may be photovoltaic and/or formed in one single semiconductor block. Optical fibre bundles, Fig. 9 (not shown), may couple the lenses 27, 29 to the detectors. A prism, Fig. 10 (not shown), deflecting the light from a lens on to an array may be moved instead of the lens.