Someone asked...
>Wouldn't white be too brilliant for nighttime work? I mean, if
>it's totally dark, and you turn on the white backlight, the starkness of it
>would hurt, wouldn't it? Does anybody have any experience with white
>backlighting? Isn't that why the lighting is green?
Someone answered...
>Longevity- Green phosphor lasts longer.
>Sensitivity- The color green is at the center of the eyes peak sensitivity.
>Cost- Green is marginally cheaper.
Never being able to resist a chance to show how smart he is, Frank chimes
in...
>From a biological point of view black and white would be best as the eye is
most receptive for that. Why's that? Well...
Your eye's retina basically consists of two kinds of receptors. As I don't
know
the english words, let me call them their german names: Staebchen and
zaepfchen.
Both have the job to translate the light they see into nerve impulses.
Staebchen,
however, know nothing about colors. All they can handle is differences in
brightness. The up side is that they are much much more sensitive that their
counterparts, the zaepfchen. That is the reason why you can see at night
which
not too much light around, and it is also the reason that you can't see
colors
at night.
Zaepfchen have the job to recognize colors. Unlike the staebchen they can
only work
if there is a fair amount of brightness present. On your retina there are 3
different
populations of zaepfchen, each trained to receive a different frequency
range.
About 64% of the zaepfchen prefer light of a longer wave length (if you can
call
half of a thousandth part of a millimeter long), making them top notch
receptors
for red light. Another 32 percent of the zaepfchen, preferring another wave
length, take care of receiving the green light. The rest merrily receive
what's
remaining, i. e. the blue light.
Mixing colors additively (as the eye does) would result in the color white
if all
3 colors are the same "strength". However, if you took 3 flashlights with a
color filter on each of them and put the 3 beams on top of each other, you
wouldn't
see white. The reason for that is that the zaepfchen have a somewhat
different sensitivity
even if stimulated with their preferred wave length. Blue is least
sensitive, red
is somewhere in the middle and green is most sensitive.
Maybe this was the reason most people chose green for backlighting. Another
reason is
that (I think) green backlighting requires less power than any other color.
Frank
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