| 摘要 |
PURPOSE:To minimize the number of contacts of a lens mounting part, by constituting so that a focus detecting signal which takes a prescribed value at a focused point and varies a value continuously in accordance with a position of a lens, at other point is provided, and is used for controlling a rotary direction of a lens motor. CONSTITUTION:A driving circuit is incorporated to the side of a lens, and drives a lens motor M in the forward and revese directions when a focus detecting signal Vf is applied from the side of a camera body. The focus detecting signal Vf continuously varies, for instance, toward ''0'' from a distance infinity , and becomes a constant value Vs within a range containing a focused point. When the focus detecting signal Vf is applied to an input terminal Vin, a signal by which long and short distance sides become symmetrical centering around the focused point is formed through a voltage amplifying circuit AMP, etc., an intermittent signal Vp according to amplitude of an absolute value signal 1Vf1 is formed through a VF converting circuit V/F, and a speed is controlled through a driving circuit MD. On the other hand, an output signal of a comparator CM decides whether the motor M is rotated in the forward or reverse direction. In this way, one signal path between the body and the lens is sufficient except ground, and the number of contacts is minimized. |
