| 摘要 |
PURPOSE:To remove the influence due to the power source and voltage variation of light measuring output, by fixing the voltage between the emitter and the collector of a transistor being a constant-current source for applying a current to the common source of a differential amplifier. CONSTITUTION:When a power source switch is closed in cooperation with the push-down of a release button of a camera, voltages VCC, -VEE are respectively applied to power source lines. On the other hand, a constant-voltage circuit 7 applies constant-voltage between the base and the emitter of a transistor 8 and to resistance 9. The collector currents thereof are flowed to transistors 10, 11. Because the base and the emitter of the transistor 10 and that of the transistors 18, 31, 33 are respectively connected in common, these transistors respectively come to constant-current source. In addition, the bases of a transistor 19 and the transistor 11 are the same potential, the voltage between the emitter of the transistor 19, that is, the collector of the transistor 18 and the emitter thereof becomes constant regardless of VCC, -VEE. |
