Talk of an e-paper based iPad has rumbled around since the reveal of the first-gen model, but so far Apple has proved unwilling to move beyond its multi-purpose IPS LCD display and consider either monochrome or color e-ink panels. According to a freshly published patent application by the company, however, they've at least given thought to the merits of electronic paper; in a submission titled "Systems and Methods for Switching Between an Electronic Paper Display and a Video Display" Apple describes a layered display sandwich which would combine traditional LCD and e-paper screens.
Rather than an all-or-nothing choice of either the electronic paper or LCD panels, the screen would be divided into segments which could selectively be set to show one or the other. That could mean video playback on the top half of the screen, using the color LCD, and text underneath, using the e-paper.
The hardware isn't the only special thing Apple is hoping to patent, however. The submission also describes a system of intelligent switching which would analyze to what extent the on-screen graphics and text were dynamic and moving, deciding between the two panels automatically depending on which is better suited to the content. So, static text would trigger the e-paper display, while video content would activate the LCD display. Alternatively, the color composition of what was being displayed could trigger the change.
What would of course be necessary is an e-paper or LCD display that could be suitably transparent/translucent to allow the other layer to be seen through. Alternatively, Apple could look to technologies like Qualcomm's mirasol, which offer both the low power consumption and zero-backlighting requirements of traditional e-paper, but can also show color images at video-friendly refresh rates. Still, mirasol and other color e-ink technologies still lack the saturation and refresh rates of LCD.