Why Bother With a PenTile RGBW LCD if an RGB Stripe is Available?

People have written about the PenTile RGBW in the Motorola Atrix and have wondered why Motorola would choose PenTile if they could have used the conventional RGB stripe. In following some blogs it was interesting to see that some people understood the reason, but let me explain it again here.

The key value proposition for PenTile RGBW LCDs is to save power. And not just a small amount of power but a sizable amount of power. Using one industry standard for a usage model, JEITA, it is easy to show that PenTile RGBW can save about 40% of the power compared to the equivalent legacy RGB stripe LCD. That is nothing to sneeze about. Baseband processor developers have spent countless hours just trying to save 10 microwatts of power, but this saves  tens of milliwatts.

For a phone, a very significant consumer of power is used by the display and in particular the backlight in the display. The PenTile RGBW saves power in two ways. First, it has larger subpixels which means that a smaller percentage of light is blocked by the subpixel transistor and buss-bar and more is available to light up the panel. This is sort of like comparing a fine mesh window screen to a coarser mesh screen. More light gets through the coarser mesh screen.

Secondly, one-quarter of the subpixels are  white subpixels. By white, it means that these are clear, letting light from the white LED backlight  pass though almost unobstructed. R, G, and B subpixels each absorb all colors except for one. Light that is absorbed in color filters is turned into unwanted heat and is wasted. So much of almost all content is white or near white that this is worth writing home about.

This translates into either more brightness, or longer time between charging, or thinner and lighter phones. In a compute intensive phone like the dual-core Atrix saving power is important.

So, not only is a bunch of power saved, but the white subpixels allow you to have really brilliant whites. For images where light reflects off of water or metal it now displays a brilliance that is much more like real life than has been experienced with legacy RGB stripe displays.

Save some power with PenTile RGBW.

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