| 摘要 |
PURPOSE:To eliminate complicating of a device by using means of converting the extent of mechanical movement of a moving member to an electromagnetical signal and comparing the same. CONSTITUTION:When a release forward travel member 13 travels left in accordance with the operation of the shutter release, the engaging part 54d of an engaging member 54 receives the force in the direction disengaging from an escape tooth 15a but since an attraction piece 9 is attracted to a magnet 10, an attraction member 7 inhibits the rotation of an auxiliary ring 16 and a lens extending member 1 by means of a pin 54c. When the magnet 10 is de-energized temporarily by a pulse signal, this attraction is released, and the rotation of the ring 16 and the lens 1 is permitted, and where the part 54d goes beyond the tooth 16a, the other engaging part 54e engages to the tooth 16a. In this way, the ring 16 and the member 1 rotate by each one pitch at every one pulse, hence, the necessary extent of extension of a photographic lens 2 is set surely by generating pulses of the number corresponding to subject distances. |
