| 摘要 |
PURPOSE:To light discharge lamps in multiple branch paths connected in parallel and control the dimming by selecting the connection states between individual branch path contacts and the common contact with a connection switching means according to the desired illuminance. CONSTITUTION:When a selector switch 57 is switched to the switch position that a terminal A is connected to both terminals B, C, the first branch path constituted of a discharge lamp 53 and the second branch path constituted of discharge lamps 54, 55 are connected to an inverter circuit in parallel. The current quantities flowing to individual branch paths are balanced so that the prescribed powers are fed to the first branch path and the second branch path by a balancer transformer 52. The discharge lamps 55, 54 are lighted even after the discharge lamp 53 is lighted, i.e., the all-lamp mode is attained to light all lamps. When the switch 57 is switched to connect the terminal A to only the terminal B, only the second branch path constituted of the discharge lamps 54, 55 is connected to the inverter circuit, and the two-lamp mode is attained. When the terminal A is connected to the terminal C, the one-lamp mode is attained. |
