| 摘要 |
1338852 Control systems for gas discharge lamps PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES 1 Sept 1972 [4 Sept 1971] 40577/72 Heading H2H [Also in Division F4] A circuit for dimming one pair of low pressure mercury vapour lamps 11, 11<SP>1</SP> whilst simultaneously increasing the brightness of a second pair of similar but differently coloured lamps 12, 12<SP>1</SP>, or vice versa, so that the total luminous flux emitted by the lamps remains substantially constant and the general colour rendering index remains above 80, comprises two pairs of antiparallel thyristors 55, 56 and 55<SP>1</SP>, 56<SP>1</SP> controlling the respective pairs of lamps and drivers 58, 58<SP>1</SP> which regulate the triggering of the thyristors, the variable resistors 64, 64<SP>1</SP> which belong to the respective drivers being mechanically coupled in such a manner that one resistance value increases whilst the other decreases. Each pair of thyristors is connected to a respective pair of ballast impedances 62, 63 or 62<SP>1</SP>, 63<SP>1</SP> in series with a corresponding pair of lamps, the other ends of the lamps being connected to one terminal 51 of an A.C. mains supply. The other mains terminal 50 is connected to the thyristors via an auxiliary inductor 52 shunted by a switch 53. |
