Re: [NTLK] Red backlights (was: Need a new backlight)

From: Humphreys, David (URB) (david.humphreys_at_honeywell.com)
Date: Thu Feb 05 2004 - 10:20:08 PST


> -----Original Message-----
> From: Nathan Turnage [mailto:nturnage_at_andadv.com]
> Sent: Thursday, February 05, 2004 12:27 PM
> To: newtontalk_at_newtontalk.net
> Subject: Re: [NTLK] Red backlights (was: Need a new backlight)
 
> Yes, but the problem is that the red part of the visual
> spectrum is the
> easiest to be seen by human eyes.

Er, actually, ~530nm is the most receptive and that's GREEN.

The reason red is used for night lights is precisely for the opposite reason - the eye is fairly insensitive to it and
so it doesn't ruin your night vision.

> We have a great deal more
> receptors in
> our eyes to pick up the red color. That is followed by green,
> then blue.

True. By population, about 64% of the cones are red-sensitive, about 32% green sensitive, and about 2% are blue
sensitive. However, as far as final sensitivity is concerned, they are equal but the details on how this is achieved is
still unknown.

> As far as the red BL in concerned, more red light would entering your
> eyes and they would become weary more quickly. Not to mention
> that it is
> very difficult to see black text on a red background.

Your eyes would not be affected as greatly with the red light as opposed to green or amber. Black text on a red
background is hard to see as a consequence of contrast rather than luminosity.

>
> -Nate
 
Regards,

PCBman

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