| 摘要 |
PROBLEM TO BE SOLVED: To provide a method effective for realizing improvement of picture quality and reduction of power consumption by backlight control. SOLUTION: Each lamp current is converted into detection PWM after being faintly smoothed, and the detection PWM is digitalized by a pulse width counter, which is subtracted from a target value, and is outputted as an input error signal after addition of non-linear characteristics, which is then integrated by a loop filter 62 to have a control signal generated by a steady-state closed loop. The steady-state control signal is then outputted to soft waveform generating parts 350-1 to 350-4 provided for each lighting block inside a drive pulse generating part 56, and is outputted to pulse conversion parts 370-1 to 370-4 as output amplitude signals after soft-start/stop waveforms are generated by each soft waveform generating part. Here, steady-state achievement signals showing achievement situations toward the steady state are outputted to an NOR circuit 344 by the soft waveform generating parts 350-1 to 350-4, and are outputted to the loop filter 62 as non-steady-state signals. COPYRIGHT: (C)2008,JPO&INPIT |
