| 摘要 |
PROBLEM TO BE SOLVED: To provide the driving device and the driving method of a back light capable of obtaining the synchronizing signal of an inverter circuit having a proper frequency and the proper driving driving power of a fluorescent tube even though the video signal having a different synchronizing frequency is inputted. SOLUTION: Since a discriminate circuit 1 discriminates the form of a video signal based on the synchronizing frequency of the video signal or the frequency of a horizontal synchronizing frequency Sync and determines a frequency diving ratio so as to become larger as the frequency of the horizontal synchronizing frequency Sync becomes higher and also the circuit determines the pulse width roughly proportional to the cycle of the horizontal synchronizing frequency sync which is frequency divided, a pulse generating circuit 2 supplies driving pulses Pd having an almost fixed cycle or an almost fixed duty cycle to an inverter circuit 5 regardless of the form of the video signal. |
