| 摘要 |
PURPOSE:To prevent unnecessary long-time exposure by an diaphragm priority automatic exposure camera circuit composed of a linear circuit, by controlling its shutter by providing a time constant circuit which generate a time signal exceeding a photometry interlocking range. CONSTITUTION:The charged voltage of capacitor C3 of time constant circuit 9 is applied to voltage detecting circuit 9', which generates a time output when the charged voltage of capacitor C3 exceeds reference voltage Vr. Voltage detecting circuit 8, generating shutter time calculated by arithmetic, detects the charged voltage of capacitor C2 with the same reference voltage Vr. Outputs of those voltage detecting circuits 8 and 9' are inputted to the NOR gate circuit composed of transistors Q2 and Q3 and resistance R2, and transistor Q1 holding the following shutter blind with a voltage comparison output inverted early to a high level is turned off to finish exposure. Consequently, the exposure extending for a long time outside of the photometry coupling range by fine light current can forcibly be prevented. |
