| 摘要 |
The invention relates to an electronic ballast for a discharge lamp, comprising a drive circuit supplying high-frequency current to the lamp and including two power switches (V1, V2) and control circuits therefor for controlling the power switches, such that the parallel half-waves of the lamp current pass through a first power switch (V1) and the reverse half-waves through a second power switch. Each power switch (V1; V2) is provided with its own, independently operating control circuit and each control circuit is provided with means (R1, R3, R8, R7) for sensing a current passing through and a voltage prevailing across the appropriate power switch (V1; V2) as well as with means (V3; V4) for controllably bringing the appropriate power switch (V1; V2) to a conducting state as a certain voltage prevails thereacross and to a non-conducting state as soon as a current passing therethrough reaches a certain threshold value (Ik; Ikl).
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