Importance

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Abstract

The operational range of an adjustable focus lens is subdivided into a plurality of focus zones, of finite size, by a lens control system that produces a plurality of discrete signals representative of said focus zones, said control system utilizing bidirectional drive means to position the movable element of said lens to one of said focus zones from any position within said operational range in order to focus an image of a remote object at an image plane. The present invention optimally increases the focusing speed and the focusing repeatability of said control system while equalizing and minimizing the focusing error introduced into said control system resulting from the use of such focus zones with bidirectional drive means, by anticipating the arrival of said movable lens element at the desired focus zone, disabling the lens drive means for a limited period of time prior to the time that said lens element arrives at said desired focus zone, and then having said drive means provide a pulsating driving force to said movable lens element until said movable lens element reaches said desired focus zone.

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First Claim