| 摘要 |
A ballast ( 11 ) includes a variable output DC converter source ( 12 ) and an inverter circuit ( 14 ) arranged to provide AC output voltage to an electro-luminescent (EL) lamp ( 16 ). A Q factor of EL lamp can characterize the age of the EL lamp. A series resonance-parallel loaded circuit and two voltage detector ( 18, 20 ) are constructed to measure the Q factor. A processor ( 17 ) controls the output of DC voltage source in accordance with a look-up table containing constant brightness algorithm based on the derived voltage and Q relationship.
|
