| 摘要 |
PURPOSE:To secure the off operation of a photothyristor while preventing a transistor from being applied with a puncture voltage by making use of the constant-current effect of FET. CONSTITUTION:Photothyristors SCR1 and SCR2 are connected in common at cathodes and anodes of SCR1 and SCR2 are connected to output terminals A and C of the switch circuit respectively; and collectors of transistors TR1 and TR2 are connected to gates of SCR1 and SCR2 and while drain D1, gate G1 and source S1 of (n) channel FET1 are connected to terminal A, cathodes of SCR1 and SCR2, and the emitter of TR2, drain D1, gate G2 and source S2 of FET2 are connected to terminal C, cathodes of SCR1 and SCR2, and the emitter of TR1. Further, resistance R1 is connected between the emitter and base of TR2, R2 is connected between the emitter and base of TR1, and resistances R1 and R2 are connected via resistance R3. Then, SCR1 and SCR2 are driven by light emission diode PD. |
