| 摘要 |
PURPOSE:To enhance the degree of allowance for the withstand voltage of a thyrister in use in the normal direction by disposing a series resistor for a Zener diode and a Zener diode in parallel in a circuit wherein a resistor for controlling gate load current and a negative direction diode are connected in series, and thereby providing the current control resistor furthermore with a negative characteristic temperature sensing element in parallel. CONSTITUTION:A current lighting device is additionally provided with a resistor 5, a Zener diode ZD1 and a thermister Th. When a device is formed in this way, increasing voltage is controlled to be definite one VZD1 by means of the resistor 5 and the diode ZD1 even if AC power voltage VE is increased, negative current flowing in a gate therefore acts as a resistor R4 so as to be remained roughly constant. In addition, high voltage pulses Vpp which are resultantly generated are maintained constant, at least, the cause which breaks down a SCR acting as a single direction thyrister with gate Thy is thereby dissolved. |
