| 摘要 |
PURPOSE:To enable to keep the oscillation even with strong incident light, by connecting a Zener diode between the base of photo oscillation element and the negative electrode of power supply. CONSTITUTION:The photo oscillation circuit is constituted by connecting the collector C of the photo oscillation element 1 to the positive electrode of power supply 2, connecting the emitter E of element 1 to the negative electrode of power supply 2 via the resistor 3, and connecting the Zener diode 4 between the negative electrode of power supply 2 and the base B. When light X is incident and the voltage drop Vo by the current I and the resistor 3 is greater than the Zener voltage VZ of the diode 4, back bias is made between the E and B of the element 1 to interrupt the current of the element 1. When the element 1 transits from ON to OFF, back bias is made between the collector C and the gate G, and the OFF state of the element 1 is continued while back bias for the time being, due to junction capacitance. When light is intensed, the photo current between C and G of the element 1 is greater, the time back biased between C and G is shorter, and the oscillation frequency is greater as shown in Figure as the incident light increases. |
