| 摘要 |
PURPOSE:To improve the focusing efficiency by providing limit switches, which can be turned on/off with a lens, in both ends of the moving range of the lens. CONSTITUTION:An operating element 1a is attached to the upper end part of a lens 1, and a pair of limit switches 11a and 11b are arranged apart from the lens 1 in both ends of a moving area A in the direction of an arrow (a) corresponding to the moving range in the direction of an arrow (b) of the lens 1. That is, the lens 1 turns on limit switches 11a and 11b at both ends of its moving area A. The lens is moved to successively detect the change of a contrast signal, and the lens position where the contrast signal has a maximum value is detected, and the lens is fixed there. If the lens reaches the limit of the moving area on the way of this detection, the limit switch detects this state and driving of the lens is controlled to move the lens in the reverse direction; and if the focus exists on the outside or in the vicinity of said moving area, the in-focus state is decided at the time of turning on the limit switch and the lens is fixed.
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