[SOLVED] LCD/TFT brightness adjustment principle

[Eugen_E]

In general, for the majority of monitors, when adjusting the LCD/TFT brightness the power delivered to the CCFL is varied, or the CCFL power is kept at maximum and brightness is adjusted by varying all the pixels' transparency?
Dimming the CCFL would be more energy efficient but is harder to do...

 

[qieda]

Hi,

normally bightness is adjusted by dimming the CCFL.
The inverter, which is driving the CCFL is controlled by a PWM output of the controller IC.

regards

 

[Eugen_E]

Thanks

This is the normal method of brightness adjustment because it is energy efficient and may insure longer life of the CCFL at low brightness settings. On laptops the backlight actually is off at 0% brightness.
I asked because I had the impression on a few monitors that when brightness is at minimum, in darkness, I could see a beam of light at the screen margins, looking like the CCFL was still at high power and the light was "kept inside" by the LCD...

 

[qieda]

Hi,

at least all the TFT monitors, which I know are dimming the backlight.

Hope this helps

regards