Patent ID: 7405721
Filing Date: 2008-07-29
Classification: G09G,H05B

Abstract:
1. A liquid crystal display device comprising: a liquid crystal display panel; a light source device having a discharge tube; and a light source driving circuit driving the discharge tube which performs a blinking operation in synchronism with a frame period with only one ON period thereof in the frame period, said ON period of the blinking period being shorter than the frame period, wherein the light source driving circuit includes a primary side circuit receiving voltage pulses in synchronism with a burst signal which turns on and off alternately only during ON periods of the blink operation and stays off during OFF periods of the blink operation, and outputting a primary voltage, a frequency of the burst signal during the ON periods of the blink operation being higher than a frequency of the blinking operation, and lower than a frequency of a lamp current and a lamp voltage of the discharge tube, a transformer circuit boosting the primary voltage to an alternating voltage, and a secondary circuit applying the alternating voltage to the discharge tube, wherein the primary side circuit includes a first active element comprising a first terminal receiving the voltage pulses via a first resistor, and a second terminal connected to one end of the transformer circuit, a second active element comprising a first terminal receiving the voltage pulses via a second resistor, and a second terminal connected to the other end of the transformer circuit, and a third active element comprising a first terminal connected to a third terminal of the first active element and a third terminal of the second active element, and a second terminal connected to a reference voltage, and the third active element turning on in a burst-on period of the burst signal and turning off in a burst-off period of the burst signal, wherein voltage amplitudes applied to the discharge tube during the burst-off period are greater than voltage amplitudes applied during the burst-on period, and wherein current amplitudes applied to the discharge tube during the burst-off period are greater than zero, and smaller than current amplitudes applied during the burst-on period.