I used to have a GBA that didn’t have any brightness, I don’t understand how that works, if you turned of the lights you couldn’t see anything. I also don’t get why isn’t it used in modern devices, like using that technology to make a kindle with a colored screen would be cool and useful.
In: Engineering
The modern Light Emitting Diode (LED) technology is based on having tiny little LEDs act as individual light-emitting red/green/blue pixels. The default is “black” with everything off, but adding more power adds brightness to each pixel, and the right combination can get you any color even up to bright whites.
The older Liquid Crystal Display (LCD) technology worked by using a polarized optical filer and tiny crystal cells that would deform under electricity to twist the polarization of light. Basically, light passing through the crystals would be polarized, and if the polarization lined up with the built-in polarizing filter all of that light would come through, but if it were lined up in the perpendicular direction you’d block all the light, and changing the amount of electricity to the crystals would change to what extent you were blocking light from 0% to 100%. This can work either with a white backlight, or by white ambient light coming in (partially blocked) hitting a mirror and coming back out (again partially blocked).
Unfortunately, that old LCD tech isn’t great for things like making a “Kindle color” because the crystals required constant electricity to maintain a given orientation. This is different from modern ePaper technology which uses electricity to move around some little pigment molecules inside a little pixel/cell, but which requires no electricity once those pigments have been parked in place (and is precisely why they have such great battery life, not just the “no backlight” thing). Not all hope is lost, though, as ePaper companies are very much actively working on the technologies needed to incorporate more pigment colors in their displays. It’s just still new and expensive technology and not quite as high-resolution as the more common black-and-white ePaper seen in Kindle screens now.
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