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x200/201/s Power consumption vs color
Posted: Sat Jul 04, 2015 5:23 am
by X20055
Does displayed color affect power consumption in x200/201/s?
Say, we put big white image, leave for few minutes then measure power consumption. Next we go for black image and measure again. We continue for all RGB colors and such. Would it change anything?
I am using "12.1" TFT display with 1440x900 (WXGA+) resolution (LED backlight) 250 nits" screen.
Re: x200/201/s Power consumption vs color
Posted: Sat Jul 04, 2015 5:38 am
by 600X
No.
Re: x200/201/s Power consumption vs color
Posted: Sat Jul 04, 2015 5:48 am
by MrMaguire
The actual LCD panel doesn't use very much electricity at all, the back light uses by far the most. So with the back light being completely on or completely off depending on whether the display is on, LCD displays have quite a consistent draw on power.
CRTs (and I think plasmas too) are the ones that will draw more power when the screen is showing a fully white image compared to fully black. This is due to the electron guns in the CRT (and the plasma thingies in a plasma display) having to fire electrons at a much larger portion of the phosphor screen (or all of it), which uses more power than not firing many (or any at all) electrons.
Re: x200/201/s Power consumption vs color
Posted: Sat Jul 04, 2015 12:49 pm
by precip9
Yes, it does. Not exactly color, but the rule is this:
1. An LCD pixel consumes the least power, ie, power-off state, when it is transparent.
2. To drive the pixel away from transparency, an electric field must be applied.
Since display schemes are typically bright message on dark background, they are not optimal for power use. This is why, with Power Manager selection of battery-stretch mode, the display scheme can be switched to black-on-white.
The difference in power consumption is significant when the backlight is set to low brightness. At typical brightness, the annoyance of a black-on-white display scheme is not worth the savings.