OSCILLATION FREQUENCY CONTROLLER AND DISCHARGE LAMP LIGHTING DEVICE

摘要

PROBLEM TO BE SOLVED: To control timing of oscillation frequency change to prevent circuit balance from being destroyed when the oscillation frequency of an inverter circuit provided in a discharge lamp lighting device is changed.

SOLUTION: An inverter circuit 3 is connected to a load circuit 4 and converts a direct current into a high-frequency current. An oscillation frequency controller 100 supplies rectangular-wave voltage to the inverter circuit 3 and thereby controls the oscillation frequency of the inverter circuit 3. The controller detects a period for which the direction of a current passed through the inverter circuit 3 is positive, and determines it as a period when an output of timing rectangular-wave voltage for causing the inverter circuit 3 to generate a changed oscillation frequency is detected.

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