Victor Company of Japan, Limited

Kaichiro Nomoto

Takashi Shinozaki

Yoshichi Otake

Yoshichi Ohtake

An automatic focusing apparatus having a focusing lens system and an image pickup device for converting a light beam incident thereon into the corresponding electrical signal. The automatic focusing apparatus is arranged so that focusing is performed in accordance with the focus voltage obtained from a predetermined high-frequency component of the electrical signal, on the basis of the fact that the level of the focus voltage corresponds to the sharpness of the resultant image. The focus voltage is successively compared with each of a plurality of reference voltages predetermined to be increased in steps. The focusing lens system is controlled in position in accordance with a comparison between the first reference voltage agreeing with one of the focus voltages and the second reference voltage agreeing with another focus voltage so that the focusing lens system approaches the focus position. When the first and second reference voltages are equal in level to each other, the focusing lens system is controlled to take the middle point between the position corresponding to the first and second reference voltages.

Automatic focusing system

A video camera with an optical system including a zoom lens system and a rear lens system provided therebetween wherein focusing is performed by varying the distance between the rear lens system and an imaging pickup device of the video camera. The video camera further includes a first sensor for sensing the position of the rear lens system to detect a relative distance between the rear lens system and the image pickup device, a second sensor for sensing the position of the zoom lens system to detect a focal length of the optical system. An arithmetic unit provided in the video camera calculates a distance to an object on the basis of the detected relative distance and the detected focal length and, in response to zooming operation, calculates a relative distance between the rear lens system and the image pickup device on the basis of the calculated distance to the object and the focal length detected by the second sensor. The arithmetic unit generates an error signal on the basis of the difference between the calculated relative distance and the relative distance detected by the first sensor and controls the position of the rear lens system on the basis of the generated error signal.

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Tokyo, Japan

Kaichiro Nomoto