| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lighting device capable of surely stopping supply of a D.C. voltage even in a situation where a current value (voltage value) rapidly changes over a predetermined time like spark noise. SOLUTION: A noise detection circuit 6 is provided with a comparator with hysteresis, voltage-converts an input spark noise-superposed current, compares it by a comparator (operational amplifier OP1), and outputs, to a thyristor 5, a low signal when it is higher than a reference voltage, and a high signal when it is lower than a voltage hysteresis line. The thyristor 5 outputs a voltage for controlling a power supply circuit 1 to lower a primary-side effective voltage of an inverter transformer circuit 1 when the input signal is low. In this case, a low state is continued with respect to spark noise by setting the voltage hysteresis line relatively low, and the effective voltage is suppressed. COPYRIGHT: (C)2008,JPO&INPIT |
