Patent ID: 7489295

Claim:
A liquid crystal display device comprising: a liquid crystal panel to display an image according to a video input signal; a light source to illuminate said liquid crystal panel when a driving pulse voltage is applied; and a light source driving circuit having a resonant circuit containing stray capacitance that said light source has and a resonant capacitor to exercise PWM (pulse width modulation) light control by applying said driving pulse voltage whose frequency is set at a value in a vicinity of a resonant frequency of said resonant circuit intermittently to said light source at a pulse frequency and at a duty ratio set respectively for the PWM light control; and wherein said light source driving circuit comprises a driving pulse setting unit to detect a frequency of a horizontal sync signal and a frequency of a vertical sync signal contained in the video input signal, to set/change the frequency of the driving pulse voltage and the resonant frequency of said resonant circuit in a manner to correspond to a change in the frequency of the horizontal sync signal, and to set/change the pulse frequency for the PWM control in a manner to correspond to a change in the frequency of the vertical sync signal.