| 摘要 |
PURPOSE:To make it possible to improve the response delay of a photometry output at power-ON time due to a latch phenomenon by interposing a voltage follower circuit between a reference voltage source and logarithmic diode and also by connecting a time constant circuit to its input terminal. CONSTITUTION:Between constant-voltage circuit 2 and logarithmic diode LD, the voltage follower circuit of OP amplifier 3 is interposed and the voltage-dividing time constant circuit composed of resistances R1 and R2 and capacitor C2 is connected to the input terminal of the follower circuit, namely, the non-inversion input terminal. Therefore, reference operating voltage Vref of the photo current converter circuit composed of OP amplifier/photo diode PD and logarithmic diode LD is the output voltage of the voltage follower circuit by OP amplifier 3 and becomes equal to voltage VN at voltage-divislon point N of the time constant circuit. If the rise of the potential of non-inversion input terminal A of OP amplifier 1 when the power supply is put to work is equalized to that of its output VO by selecting delay time, the feedback operation of OP amplifier 1 starts as reference voltage Vref rises, so that output VO will immediately be in a steady state without being inverted. |
