| 摘要 |
<p>Camera comprises a photoelectrically controlled stop adjuster of which the measuring and control mechanism comprises a driving coil (1) and a damping coil (3) in which is induced, on adjustment of the mechanism, a voltage which is opposite the voltage which controls the driving coil. The stop adjuster controls an alarm device which indicates passage beyond its control zone to prevent faulty exposure. A signal which causes a change in the state of the alarm device is obtained from a fluctuation in voltage which occurs on reaching the boundaries of the control zone as a result of the transition of the control mechanism from movement to stopping. Pref. the signal is picked up at the output of an amplifier (8) to one input of which is connected the damping coil, and which is also connected to a measuring bridges (4-7) containing a photoresistor (4).</p> |
