On Thursday 21 May 2009, zogg wrote: > Thats intresting. What could have stopped them from making it > non-monochrome in daylight?
Probably cost and efficiency as these were major factors in OLPC. If PixelQi don't start producing screens that are colour in daylight then I guess there's a technical reason as well. Based on the explanation below I would have thought adding the coloured filters between the LCD and the reflective layer would drop backlight efficiency only a little since the prism has already split the light, but I'm no expert. The extra component requiring precision placement would add cost though. > Tim Schmidt wrote: > > On Thu, May 21, 2009 at 9:12 AM, zogg <zoggif...@gmail.com> wrote: > >> Looks like LCD for indoors are common, and for outdoors theres scarcity. > >> So, do you know any manufacturers, or at least in what direction should > >> i try and look at? > > > > The OLPC has an LCD which is very easy to read in daylight. When > > backlit, it appears as a color LCD, but when frontlit (as from the > > sun), it appears greyscale. This is a function of the OLPC's very > > efficient backlight system (instead of using colored filters to block > > out 66% of the light from the white backlight for each pixel, they use > > a fresnel prism to split the backlight into it's component wavelengths > > on pixel boundaries. Thereby allowing nearly 100% of the light > > produced by the backlight through to your eyes, as opposed to less > > than 33% for typical LCDs. Light from the front of the LCD passes > > through the pixels, and is reflected by a silvered layer, back through > > the pixels to your eyes, never passing through the prism, so what > > would normally be colored sub-pixels appear as greyscale pixels. > > > > --tim _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community