[ltp] Re: fan problem on R51

[Austin Murphy]

On Thu, 04 Nov 2004 19:07:42 +0100, Jan Girlich <vollkorn@freenet.de> wrote:
> Moritz Karbach schrieb:
> > 3,5h is quite impressive... But I think the background image's got nothing to
> > do with that - except for that a black image maybe look nicer with low
> > background brightness...
> 
> I don't know any exact number about how much to save with different
> colors. But just think about this: IMHO colors on LCDs are put together
> by three LEDs: red green blue. white is the combination of every LED and
> black is no LED. So you'd probably save some power if you "switch off"
> every LED.

An LCD panel does not use LED's.  An LCD is large array of Liquid
crystals. A liquid crystal has the ability to block light or let light
pass through based on how much electricity is applied to it.  Each
pixel has three Liquid Crystals, one for each color.   On top of each
LC is a filter for either Red, Green or Blue.

In the side of the LCD panel there is a flourescent light tube. 
Sometimes there is one on both sides.  This light shines through a
sheet of reflective plastic that covers the back of the liquid
crystals.  This Backlight does not change except when the overall
brightness is adjusted.

The backlight seems to be the primary consumer of energy in the
display.    I'm not sure how much electricity is consumed by the LC
control circuitry or whether a largely black image will consume less
power than a mostly white display.

LED's and plasma displays work on completely different properties. I
think plasmas draw several times as much power as LCD's and LED's are
very bright and efficient but not very small.

Austin