Patent ID: 6181087
Filing Date: 2001-01-30
Classification: H05B

Abstract:
A discharge lamp lighting apparatus comprising:an inverting circuit for converting a DC input into a high frequency output;a load circuit which is connected to said inverting circuit and is constructed by a plurality of discharge lamps;a detecting resistor connected between a terminal of said inverting circuit and a ground;an integrating circuit for integrating a voltage generated in said detecting resistor;an operational amplifier which receives an output of said integrating circuit as a negative input, receives a predetermined target value as a positive input, and performs an error amplification;a driver for controlling a switching frequency of said inverting circuit on the basis of an output of said operational amplifier;a frequency detecting comparator which inputs the output of said operational amplifier and whose output value is switched in the case where a frequency converted at an input value exceeds a predetermined value;a control circuit for switching an operating state of said driver depending on the output value of said frequency detecting comparator; anda latch circuit for holding the operating state switched by said control circuit in the case where said converted frequency exceeds the predetermined value.