Electronic Design

E-paper Makes E-books Exciting

This year was the year for electronic-paper displays (EPDs), or e-paper. Next year, we’ll see a flood of e-book readers from a wide range of vendors. Two things make E Ink’s e-paper displays interesting.

First, they don’t draw any power if the image on the display is unchanging. E-paper displays also use very little power to update. Second, they offer superior viewing quality. The displays employ a reflective technology with high contrast that’s easy on the eyes and comparable to a printed book page.

Of course, there are limitations. Their page update is slower than more power-hungry display technologies such as LCDs. Also, the lack of a color option is a significant impediment for some applications, such as streaming video.

Displays have been using the E Ink technology for years. First shown at the 2006 International Consumer Electronics Show, the Lexar JumpDrive employs a tiny bar segment display to reflect flash memory storage usage (Fig. 1). E Ink displays also have even been part of the cover, literally, of Esquire magazine.

E Ink will likely have more interesting things to display in 2010. Larger and faster color displays are in the works. Developers also will be able to take advantage of Marvell’s Armada 16XE microcontroller, which integrates the e-paper drivers, reducing cost and footprint.

Amazon’s Kindle has the massive support of Amazon and its large list of book titles. The built-in cellphone connection allows users to download content directly (and only) from Amazon’s Kindle Store. The first Kindle e-book utilized a 6-in. e-paper display with four levels of gray. The Kindle 2 and the 9.7-in. Kindle DX, released this year, have 16 levels of gray.

Sony’s Reader Touch Edition is a more open platform, supporting multiple formats including ePub and PDF plus audio formats like MP3 and AAC (Fig. 2). Sony has used e-paper for a number of years, starting with the Libre for the Japanese market in 2005.

The Reader Touch Edition has a 6-in. touchscreen display with eight gray levels and runs for two weeks on a charge similar most other e-books. A built-in accelerometer allows it to switch from portrait to landscape mode. Also, its touchscreen allows same-user operation in either orientation.

Announced in October, the Barnes & Noble nook will definitely make a splash in 2010. It runs the Linux-based Android system and looks to do Sony one better when it comes to open platforms. Additionally, it features the E Ink Vizplex display as well as a color touchscreen.

Like e-paper, Qualcomm’s Mirasol display technology uses no power to display a static image (Fig. 3). It operates like Texas Instruments’ DLP microelectromechanical- systems (MEMS) technology. But where TI uses mirrors, Qualcomm uses MEMS-based interferometric modulation (IMOD) reflective technology.

The IMOD device consists of a self-supporting deformable reflective membrane and a thin-film stack. The two plates act as mirrors in an optically resonant cavity that controls the wavelength of reflected light. Change the distance between plates using MEMS, and the reflection at ultraviolet wavelength occurs. It appears black to the human eye.

Mirasol is faster out of the chute when it comes to screen update speed. It also supports color. The challenge will be scalability. Initial versions target small displays such as cell phones. It will definitely be competition for e-paper.

TAGS: Components
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