New LCD Ditches Backlighting, Still Provides Full Color Under the Sun
The shift from CRT to LCD has been quite breathtaking. We saw display units get a whole lot thinner at the turn of the new century. For people concerned with energy efficiency, the shift is even more important, not only because it can save your pocket, but it also indirectly reduced the amount of coal used per unit time that the display unit stays on.
Today, the most energy efficient iteration of the LCD is the LED-backlit LCD. But even in the next few years, they might be ultimately replaced by OLED and quantum dot displays. That does not mean though that they can no longer be made more efficient. Take a look at this new research in Japan for example that totally eliminates the need of LCD’s to use backlighting.
Japan Display, a merged business sector that combines the LCD businesses of Sony, Hitachi and Toshiba, has recently unveiled their special low-power reflective LCD. This isn’t like your typical 7-segment digital LCD, nor is it like the monochrome reflective screens of older e-readers. This reflective LCD is capable of displaying full colors without artificial backlighting. You heard that right; Japan Display seems to have finally eliminated the most critical weak point of modern LCD technology.
The working principle of their reflective LCD does not completely eliminate the use of an external lighting source though. Instead, they have simply eliminated the need for a light source that requires energy. Technically, this means that it will collect light from an ambient source to a mirror that is placed directly below the LCD. The reflected light will then produce a monochrome image from the liquid crystal shutter, and would then be dabbed with color using a color filter layer.
But if it simply uses light that directly hits it, wouldn’t it appear in our eyes as a simple mirror? That’s true, but they have developed what is called as a Light Control Layer. As hinted clearly by its name, this is the layer that controls the amount of light reflected and the direction where it should bounce off. With this layer, a fully detailed color image can be displayed without having to worry about light simply bouncing off to display a reflected image.
According to the report, there are two versions of the low-power reflective LCD. The first one is the highly reflective version. It has a 40% reflection rate, and has 5% coverage of the NTSC color gamut. The second one is the high color purity version. It holds 36% of the NTSC color gamut, but its reflectivity is at a lower 28%.
A large bulk of the energy consumption rate of an LCD screen is usually attributed to its backlighting. But with powered backlighting practically absent in these reflective LCD’s, they could be made even more efficient that the most efficient LCD screens that we have now. This is even more amazing if you count the fact that these screens have the capability to economize energy usage for still images. They only use a very miniscule 3 milliwatts or 0.001 watts of energy when the screen is static.
Additionally, no backlighting also means that these screens could be made thinner. Indeed, they are described as paper-like, and without the electronics behind it, it would look considerably thinner even when it is stuck together with its display layers. The only remaining problem now is that you probably won’t be able to use it in the dark.
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