| 摘要 |
PURPOSE:To reduce the electric power loss, lengthen the lifetime of bidirectional thyristor and simplify the circuit, by heating a filament through an AC power source without using any bleeder resistance while controlling the phase of the bidirectional thyristor. CONSTITUTION:An AC voltage 33 synchronized with an AC voltage 32 for lighting on a lamp is full-wave-rectified and then applied to a Schmidt circuit 17, thereby producing square waves. The square waves are entered into monostable circuits 18, 19, thereby producing pulse waves. The pulse waves are entered into the base of a transistor 20 to turn it on and off. The pulse waves are thereby supplied to the gate of the bidirectional thyristor 13 to control its phase. Thereby, intermittent alternating current is supplied to the lamp 2 so that the filament is always heated. When a lamp light-on signal x is applied and a transistor 14 is turned on, continuous current flows through the gate of the bidirectional thyristor 13 and the lamp 2 is lighted on. |
