Friday, June 06, 2008

Samsung's Next-Generation LCD

A new liquid crystal material provides a wider viewing angle and reduces blur.

By Kate Greene

Clearer crystals: Samsungs' new 15-inch blue phase LCD prototype display uses a kind of liquid crystal material that enables a wider viewing angle and reduces blur. Credit: Samsung

In the battle of flat-screen displays, both liquid crystal displays (LCDs) and plasma displays have their strengths and weaknesses. LCDs are lightweight and often cost less than plasmas. Conversely, plasmas have a wider viewing angle and show crisper images of fast-moving objects. But now a Samsung prototype that uses a new kind of liquid crystal material illustrates how LCDs are overcoming their weaknesses.

At the recent Society for Information Display conference in Los Angeles, Samsung showed off a 15-inch display made with blue-phase liquid crystals, a type of liquid crystal that researchers have known about for years but that no one had ever demonstrated in a working display. Due to the optical properties of blue-phase liquid crystals, the new display has a much wider viewing angle than traditional LCDs do, and it can refresh images on a screen four times faster than early LCDs can, significantly reducing blur. Moreover, the new display can be made in fewer processing steps than today's LCDs require, which means that blue-phase displays have the potential to be less expensive.

Scott Birnbaum, vice president of LCD business at Samsung, says that the company has no plans to commercialize its blue-phase display yet, but it's easy to see the device's potential. The benefits of the new liquid crystal are particularly apparent when watching a video with a lot of action, or one that's in 3-D, Birnbaum says. There's a lot of information there, and he thinks that "it makes a difference to have ultrafast switching."

Today's LCDs don't provide a wide viewing angle because of the way that light reflects off them. When a person looks at an LCD straight on, the image is clear, but as she moves to the side of the display, the image fades because light isn't efficiently deflected at greater angles. Blue-phase liquid crystals, on the other hand, are made of crystals with a highly helical structure that reflects a larger percentage of light over a wider angle.

The other drawback with some LCDs is that a fast-moving object like a baseball has a ghostly tail that marks its trajectory. Birnbaum explains that this is because each frame of motion--and there are typically 60 frames per second--is held on an LCD screen until the next one is displayed. This differs from traditional cathode-ray-tube and plasma displays, in which frames flash on the screen at a rate of 60 frames per second, allowing viewers' brains to fill in the gaps. Newer LCDs can operate at 120 hertz, and a technology that produces extra images for these extra frames works well to reduce some blur. But due to the way that blue-phase crystals are structured, they are capable of changing orientations at twice the frequency, switching at 240 hertz, and producing a crisper picture.