A method of driving a light source unit of a liquid crystal display panel according to an exemplary embodiment of the present disclosure includes the steps of calculating average and maximum values of image signals applied to the liquid crystal panel; calculating a representative value of the image signals using the average and maximum values; determining the luminance of the light source unit according to the representative value and driving the light source unit accordingly. The representative value may be calculated from Lrep=(1−β)×Lavg+β×Lmax, where Lrep is a representative value, Lavg is an average value, Lmax is the maximum value, and β is a value that decreases as a difference between the maximum and average image signal values increases, and has a range between 0 and 1.