| 摘要 |
An integral ballast and control circuit (40) provides control of the output illumination through a timed interval controlled impedance (62), serially coupled between a winding of a magnetic ballast and series connected gas discharge lamps (12,14). When in its non-conducting state, the controlled impedance 62 interrupts the lamp discharge current. A timed control signal is applied to the impedance 62 at a gate electrode 62 by a control circuit 60 which receives power and timing signals from the magnetic ballast. The illumination level adjacent the lamps (12,14) is sensed by photocell (72) connected by leads (66) to the control circuit (60), which includes two control loops, one responding to the photocell output and the other to the lamp discharge current sensed adjacent the controlled impedance (62). |
