| 摘要 |
PURPOSE: To stabilize the light output of a lamp by providing a warming power control means which operates a lamp at a high power level for a predetermined time at startup and at restart sets a power level corresponding to off-time. CONSTITUTION: A warming-up control circuit 38 having an RC timer for operating a low-temperature lamp at a high power level for a short time during a starting period in order to perform quick warming-up of the lamp is provided. The RC timer of the circuit 38 is connected to the input terminal of a voltage follower 14, and the output of the follower 14 is input to a power control addition amplifier 40. The operational amplifier of the circuit 38 calculates the off-time of the lamp from the remaining voltages of capacitors C19, 20 at high- temperature restart. To restart the lamp after a short period, the initial power to the lamp is adjusted to the level between a standard lamp wattage and a wattage at maximum low-temperature startup. Therefore, the light output from the lamp is stabilized without depending on lamp voltages. |
