Over the past year tablet displays have greatly improved in terms of screen resolution and pixel density, but two areas that still need improving are outdoor readability and energy efficiency.
Today’s tablets with LCD screens are very bright and easy to read indoors, but outside and in areas with bright lighting annoying reflections and glare consume the screen, and colors don’t appear nearly as bright. Battery life is typically 10 hours or less for most tablets, and the screen is the main source of power drain.
By contrast ebook readers like the Kindle and Kobo have E Ink screens that are very easy to read in direct sunlight, and they have batteries that last for weeks, sometimes months. The main disadvantage with E Ink, of course, is the slow refresh rate of the screen and the fact it is best suited for black-and-white applications. Color E Ink has been in production for a few years now, but has yet to go mainstream, mainly because of high costs and the fact that colors appear dull and washed-out when not under bright light.
Given the limitations of electronic ink and LCD, it’s more likely that an alternative type of display technology will take the lead in producing energy-efficient color displays that are readable in direct sunlight.
One potential candidate is electrowetting displays. Electrowetting is an interesting technology that uses electricity to alter the “wetness” of a film of oil applied to the screen to make it change shape. In its default state the oil is flat and opaque so no light can get through. Add some voltage to the mix and the oil forms into tight little beads that allow light to pass through. Colors are then determined by controlling how much light passes through the sub-pixels with colored filters for red, blue, and green.
One of the main advantages of electrowetting displays is that they require less power. They can be backlit, frontlit, or have no internal light at all, much like E Ink. It is said that a backlit electrowetting display can achieve double and maybe even triple the battery life compared to current devices with LCD screens.
Another advantage with electrowetting displays is they are visible in bright sunlight like E Ink because no polarizing filters are required. In fact the brighter the light on the display the better it looks.
The big question is when will electrowetting displays hit the market? Right now there are two companies trying to get these new type of displays into your hands. Liquavista was purchased by Samsung a couple of years back and is the most likely candidate to get electrowetting displays onto the market first. Another contender is Gamma Dynamics, who is working on an adhesive film that manufacturers could use to laminate onto a backplane to produce ereader and tablets displays, much like how E Ink is produced now.