Importance

Loading Importance Indicators...

Abstract

The present invention relates to a drive device for one or more series-connected cold cathode fluorescent lamps having an electrical terminal at each end. The drive device has a piezoelectric transformer for converting by means of the piezoelectric effect a primary ac input applied to primary electrodes to a secondary ac output, which is removed from secondary electrodes; a drive arrangement for applying the primary ac input to the primary electrodes; and a brightness control circuit for controlling brightness. The drive device is configured so that the end electrical terminals of the cold cathode fluorescent lamp can be connected between the two secondary electrodes. The brightness control circuit detects the phase difference between the secondary ac output and the primary ac input. When the detected phase difference is greater than a specified phase difference, the drive arrangement reduces the power of the primary ac input applied to the primary electrodes. If the detected phase difference is less than the specified phase difference, the drive arrangement increases the power of the primary ac input applied to the primary electrodes.

Loading the Abstract Image...

First Claim