| 摘要 |
<p>A dimmer for fluorescent lamps which enables continuous dimming, elimination of flickering of an optical output, and stable lighting particularly at low temperature. The dimmer has a lamp voltage detection circuit for detecting a discharge voltage of the fluorescent lamp, and causes a control section to carry out intermittent frequency control so that an output frequency of a high-frequency power source is changed from a dimming frequency based on a dimming signal to a frequency higher than the dimming frequency, thereby changing a current to the fluorescent lamp to be a periodically low current, and also, when the output frequency of the high-frequency power source is a frequency higher than the dimming frequency, causes the control section to determine a lower limit preset value of dimming based on the voltage detected by the lamp voltage detection circuit, thereby controlling the output frequency of the high-frequency power source to be lower than the upper limit frequency corresponding to the lower limit preset value of dimming.</p> |
