Patent ID: 6636190
Filing Date: 2003-10-21
Classification: G02F,G09G,H05B

Abstract:
A liquid crystal display device comprising:a liquid crystal display panel having a plurality of pixels; a lighting device having at least one light source and projecting light generated by said at least one light source on said liquid crystal display panel; and a circuit for supplying alternately a first alternating current of a first amplitude during a first period t1 and a second alternating current of a second amplitude during a second period t2 to said at least one light source, said first amplitude being greater than said second amplitude, wherein said circuit controls said first alternating current and said second alternating current such that the following relationship is satisfied: first electric power E1 is lower than second electric power E2, where said first power E1 is defined as {(t1Ã—ip-p(1)Ã—Vp-p(1))/2}+{(t2Ã—ip-p(2)Ã—Vp-p(2))/2},ip-p(1)=a peak-to-peak value of said first alternating current flowing through a respective one of said at least one light source during said first period t1, Vp-p(1)=a peak-to-peak value of a voltage across said respective one of said at least one light source during said first period t1, ip-p(2)=a peak-to-peak value of said second alternating current flowing through said respective one of said at least one light source during said second period t2, Vp-p(2)=a peak-to-peak value of a voltage across said respective one of said at least one light source during said second period t2, said second electric power E2 is defined as (t1+t2)Ã—(IeffÃ—Veff), Ieff is an effective value of a current flowing through said respective one of said at least one light source during said first period t1 plus and said second period t2, and Veff is an effective value of a voltage across said respective one of said at least one light source during said first period t1 plus and said second period t2.