The screen tech trade show FPD International is going on right now in Japan and the attendees are in for a treat. Japan Display Inc is currently showing off a new 7" (1024x768) LCD screen which could present a serious challenge to E-ink's dominance of the ereader market.
The new display incorporates a couple changes in design from the norm for LCDs, resulting in a much lower power demand.
First, it forgoes the backlight found on virtually every LCD screen. As you probably know, the backlight is often the single biggest user of battery life on any tablet. By leaving it out this screen becomes one of the more energy efficient LCD screens in one fell swoop.
But that's not all that this screen offers, and here's the cool part. This display also has small amounts of sRAM incorporated into each pixel.
The other reason why LCD screens are so power intensive is that the current screens have to be constantly told to display an image. Even if the screen contents don't change, the screen still needs to be repeatedly told to display what's on screen. That means a controller chip somewhere inside the device is constantly running and sending a signal to the screen.
This new screen gets around the power issue by using static RAM to record the screen contents on a pixel by pixel basis. The RAM doesn't require any power to store current state of the screen, so keeping an image on the screen requires a minimum of power. It is so low power that its usage while displaying a static image is measured in milliWatts, while regular LCD screens have power demands measured in Watts.
For example, the display on the iPad 2 draws 2.4 Watts at maximum brightness, while the Retina display on the iPad 3 draws 7 Watts at maximum brightness.
In comparison, the new screen mentioned above draws 3 mW while displaying a static image. That means that when it's not in heavy use (reading, for example) this screen is 800 times more efficient than the one on the iPad 2.
No details have been released about the manufacturing cost, but JDI did indicate that they were ready to produce the screen now.
Update: And here's a video showing the new screen, courtesy of DigInfo.tv.