| 摘要 |
PURPOSE:To provide an apparatus for stepwise controlling brightness of a lamp, in which brightness of the lamp is changed stepwise by controlling a switching element to a certain conduction phase angle at the time when charging of a capacitor is completed, whereby switching from full-lighted mode to brightness-controlled mode can be effected instantly. CONSTITUTION:Provided that changeover switch 5 is turned to the side of first contacts 6, 6a with wall switch 7 being kept in its ON-position, lamp 3 is fully lighted since it is connected to power source E via ballast B, first contact 6a of changeover switch 5 and wall switch 7. Simultaneously with this full lighting of lamp 3, relay Ry is energized momentarily via the circuit of power source E, the first contact 6a of changeover switch 5, capacitor 19, relay Ry, diode 20 and power source E, whereby relay contact (r) is closed momentarily and residual charge of capacitor 1 is discharged through resistance 9. When the switch 5 is turned to the side of a second contact 8, on the other hand, relay Ry is not energized and transistor Tr is kept in its OFF-condition since charging of capacitor 1 is completed. |
