| 摘要 |
PURPOSE:To efficiently use a lamp, prevent the reduction of light flux of the lamp, and increase the dimming ratio even in high temperature area. CONSTITUTION:An oscillating circuit 7 for determining the oscillating frequency of an inverter circuit 4 for lighting a discharge lamp 5 is provided. A temperature detecting means 8 for detecting the tube wall temperature of the discharge lamp 5 is provided. According to the output of the temperature detecting means 8, the oscillating circuit 7 is controlled by a control circuit 9 so as to increase the supplied power from the inverter circuit 4 to the discharge lamp 5 at the time of low temperature. At the time of high temperature, it is controlled in the direction of lowering the tube wall temperature of the lamp so as to increase the luminescent efficiency. Therefore, the higher the temperature, the more the supplied power from the inverter circuit 4 to the discharge lamp is reduced. |
