Automatic exposure control for camera - uses light value capacitor storage with integrated circuit sequence control

摘要

The initial depression of the camera exposure release operates a switch mechanism which starts an electronic timing circuit whilst the reflex mirror moves out of the objective light path. During the timed interval, the photodiode or photo transistor charges a storage capacitor. At the end of the charging interval the timing circuit initiates the start of the exposure, disconnects the photocell and triggers an integrating circuit made ready by the switch mechanism. This circuit has a high input impedance and feeds its output to a discriminator circuit. When a signal value corresponding to preset and metered factors is reached, the shutter closing signal is generated to terminate the exposure.