CAMERA PROVIDED WITH AUTOMATIC FOCUSING DEVICE

摘要

PURPOSE:To save the power of an automatic focusing device by displacing a master lens group by driving a pulse motor and controlling the motor so as not to allow a current to flow into the motor when a step drive command is not received. CONSTITUTION:A preamplifier 12 amplifies an output signal from an image pickup element 7 and a camera circuit 13 generates a camera signal. Then a high frequency component extracting circuit 14 extracts a high frequency component signal from a video signal and a detection circuit 15 detects a fine variation reference frequency component from the output signal of the circuit 14. A detection signal from the circuit 15 is inputted to a synchronous detection circuit 16, which executes synchronous detection by using a reference signal outputted from a refrence signal generating circuit 17, detects the polarity and oscillation of the reference frequency component and applies the detected result to a control signal generating circuit 18. The circuit 18 executes the step drive of the pulse motor 11 through a driving circuit 19 and controls the circuit 19 so as not to allow a current to flow into the motor 11 when the step drive command is not received. Consequently a camera provided with this simple automatic focusing device capable of saving power can be obtained.