| 摘要 |
PURPOSE:To make a ripple peak value having a lamp voltage waveform to be not effected by a ripple of a inverter input by providing a lamp voltage set value correction circuit in which a set value of the lamp voltage makes a variable correction according to an input DC voltage of an inverter. CONSTITUTION:KV1set-beta.Vc is calculated with a value proportional to an input voltage Vc decreased in a lamp voltage set correction circuit 12 receiving a set value KV1set of the lamp voltage. beta is determined according to a size of a ripple of the voltage Vc. Then a constant alpha is adjusted which equals to the lamp voltage in which the peak value of the lamp voltage is set in the circuit 12, and alpha.(KV1set-beta.Vc) is determined with alpha integrated to KV1 set-beta.Vc and is made to the lamp voltage set value. This constitution eliminates the influence of the ripple of the voltage Vc of an inverter on the ripple peak value having a lamp voltage waveform, and thereby enables the ripple peak value to constantly equals to a set lamp voltage.
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