| 摘要 |
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 equalizes and minimizes the focusing error introduced into said lens control system resulting from the use of such focus zones with bidirectional drive means, by utilizing electrodynamic braking to arrest lens movement within a predetermined portion of a focus zone, once said lens has entered said zone to focus an image of said remote object at said image plane.
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