Back in April, Barnes & Noble(s bks) one-upped Amazon(s amzn) by introducing the Nook Simple Touch with GlowLight, taking e-ink reading out of the dark. The $139 device uses the same infrared touch technology as the prior model, but adds the innovative glowing screen; something not yet found on a Kindle device.
So how exactly did Barnes & Noble solve the problem of uneven light across the display? It’s not just technology magic, but science that makes it work.
Thanks to an iFixit teardown of the device, you can see how Barnes & Noble accomplished this, as well as view all of the many parts packed into the e-reader device. Along the top edge of the e-ink display are eight LED lights, evenly spaced apart.
These are the only lights used make the screen glow evenly and they’re only on the one edge. But the lights don’t shine directly down the display. Instead, the glass display has diffraction grating built-in, causing the light to be spread out across the entire screen surface, says the iFixit blog:
This diffraction grating bends and disperses the light throughout the screen. Barnes & Noble really did their homework on this one, because instead of a simple linear diffraction grating (think of a bunch of parallel slits), it appears that the diffraction grating varies throughout the glass to evenly disperse the light.
To illustrate how the glass display diffracts light across many angles, the iFixit team shined a laser through the screen’s edge. Normally, a laser appears as a single point as all of the light waves are tightly focused. Shining it through the diffraction grating however, shows how the screen spreads a beam of light out.
The solution is ingenious and I’d love to see it come to mobile devices because it would mean using fewer lights and therefore save power. Unfortunately, most smartphones and tablets are backlit, meaning the light comes from under the display, so this is an unlikely prospect for the future. Then again, I’m not a science expert, so maybe there’s an opportunity here!