| 摘要 |
PURPOSE:To reduce the power consumption of the diaphragm controlling mechanism of a single-lens reflex camera, by using stopping-down rotation force as holding force for a locking claw. CONSTITUTION:When a stopping-down ring rotates through releasing operation, a photointerrupter 32 counts pulses up to proper aperture calculated by an exposure controlling circuit, and then an electromagnet 37 is excited to attract a moving iron core 35. Consequently, a locking ratchet claw 4 bites into a ratchet 2 and is held by force in a stopping-down direction, so a stopping-down state is held even after the electromagnet 37 is unexcited. When the stopping-down ring is released after exposure operation, the ratchet releases the claw, so the claw separates by a spring 7 to return it to its original state. Thus, the electromagnet is excited only for an extremely short time, and the power consumption is reduced. |
