| 摘要 |
<p>A cold-cathode driver using a step-up transformer for driving a cold-cathode tube, which is a piezoelectric transformer the output voltage of which varies with the frequency of the input voltage. The cold-cathode driver comprises frequency-dividing means for generating driving pulse of an average frequency corresponding to frequency data outputted from frequency setting means for a dispersion period corresponding to a period of N drive pulses, a controller for controlling the control period so that the same drive can be performed at the average frequency a predetermined times A (A ≥ 2), burst pulse generating means for generating pulses with duty width corresponding to a given dimming level at the frequency outputted from the controller. The drive method is a digital one by frequency dispersion of the drive pulses, thus achieving reduction of space and cost of the driving circuit. A frequency resolution required for favorable dimming performance and lighting performance is imparted. The dimming method is a burst one, so that luminance flickering as observed in the case of a tube current control method is suppressed.</p> |
