Color Filter Could Boost LCD Efficiency by 400%
Researchers at the University of Michigan have created a color filter that could boost the efficiency of LCDs, the power hog of all your gadgets, by more than 400 percent, and no, I didn't add an extra zero there.
The researchers made an optical film that colors and polarizes the light that passes through an LCD, taking the place of the several layers of optical devices that typically serve the same function in an LCD. Those multiple layers give rise to inefficiencies: the best LCDs out today only emit eight percent of the light their backlights produce. The researchers found that the film allowed 36 percent of the light to make it through - a huge increase.
The color filter is made up of three ultra-thin layers -- two layers of aluminum enclosing a layer of insulating material -- and it only measures 200 nanometers thick. The filter is etched with slits that produce different colors when illuminated by the backlight. The slits are matched in scale to the wavelength of visible light and their length and distance apart determine the color produced.
This grating pattern is where the efficiency boost comes in. In current LCDs, a polarizing filter absorbs half the light (the part with the wrong polarization). The grating on the new filter doesn't absorb the light with the wrong polarization, it instead reflects it back towards a mirror that flips some of its polarization, letting more light pass through the filter.
Researchers are trying to improve the efficiency further and are coming up with ways to mass produce the filters, like with roll-to-roll printers.
via MIT Tech Review