| 摘要 |
An AC power supply apparatus used for an AC load of a high voltage such as a cold cathode tube. When a cold cathode tube is caused to emit a light, a DC voltage is on/off controlled at a predetermined ratio; thereafter, an AC signal of a high frequency is applied to the on/off controlled voltage in an oscillator circuit; then the resultant signal is boosted up to a predetermined level of voltage in a booster circuit; and thereafter, the AC power supply of the high voltage is applied to the load such as the cold cathode tube. For example, the light modulation of the cold cathode tube is controlled by the amount of a current caused to flow through the cold cathode tube. If the light emission of the cold cathode tube is to be suppressed below a predetermined level, the oscillation is performed by use of an AC signal having a low frequency, thereby preventing the light emission of the cold cathode tube from becoming non-uniform.
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