| 摘要 |
PURPOSE:To simplify the constitution of a circuit by inputting one output larger than the other in a pair of photodetectors to an automatic gain controlling circuit of a circuit for detecting a degree of focusing, and controlling the gain. CONSTITUTION:In outputs of photodetectors 12A, 12B, one output larger,than the other is inputted to an automatic gain controlling circuit 17, and based on the larger output, the gain is controlled. In such a way, it becomes unnecessary to constitute a circuit for obtaining the sum of the outputs of the elements 12A, 12B, and only the constitution for inputting only one output larger than the other to the circuit is enough, therefore, the constitution of a circuit can be simplified. |
