| 摘要 |
PURPOSE: To realize constant power consumption of a lamp during operation by regulating a frequency and cycle of a semiconductor switching element in an energizing state to generate a voltage between both ends of capacitor. CONSTITUTION: After therminal ends 4 and 5 are connected to a power supply, a constant voltage between both ends of a capacitor 15 can be generated based on the selection of a frequency and duty cycle of a semiconductor switching element 12 in a deenergizing/energizing state. A starting circuit activates a DC/AC converter, and then high-frequency switching elements 21 and 24 alternately attain an energizing and deenergizing state. The power of a lamp 1 is derived from the capacitor 15 to stably maintain it by means of a sensor element 22. A measured voltage between both ends of the element 22 is compared with a reference voltage supplied from a circuit 28 through a control circuit 27, and, for example, if a voltage between both ends of the lamp is lowered, the switching frequency of the switching elements 21 and 24 is reduced. This stably maintains power consumption of the lamp. |
