Electronic reader incorporates novel display technology, older processor

Electronic readers, or eBooks, have been around for a while. They emerged in full force a few years ago, but never really had a significant impact on the market. The biggest complaint was that it was hard on the eyes to look at the display for long periods of time. The user interface wasn't the greatest either.

Sony thinks it has solved those problems, with the help of a key supplier, E Ink. Its Portable System Reader (PRS) 500, which recently dropped under $300, is about a half-inch thick (about 7 by 5 in. in length and width) and weights just 9 oz. The readable display area measures 6 in. diagonally, which is about the same as one page in a paperback book.

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Thanks to the E Ink technology, called Vizplex, the high-contrast (four-level grayscale), high-resolution (170 pixels/in.) display can be read in bright sunlight. It offers a near 180-degree viewing angle.

The Vizplex imaging film is designed for high performance with black and white electronic ink pigment formulations. It's brighter and offers a faster response time compared with the previous generation active-matrix imaging film. In addition, it can be manufactured in larger sizes, up to 9.7 in.

To create the imaging film, a microencapsulated electronic ink is coated onto an indium-tin-oxide (ITO)-coated plastic substrate in a roll-to-roll process. The resulting ink film is combined with a thin adhesive and a plastic release sheet to form the Vizplex imaging film. The film is then converted into individual sheets and packaged for shipment to the TFT display manufacturer.

With Vizplex, E Ink leverages the existing infrastructure used in the manufacture of conventional active-matrix LCDs (AMLCDs), but the E Ink process flow for display-cell assembly is actually simpler. The process used to attach the Vizplex imaging film to the TFT panel is similar to polarizer lamination for AMLCDs and uses similar equipment. Other steps, such as the scribe and break process, are identical to processes for the AMLCDs.

The eBook is designed with 64 Mbytes of internal memory, which the company claims is enough to store about 80 books. If that's not enough, there's a slot for a Memory Stick or an SD memory card.

Battery life was a little hard to determine, as I didn't get a chance to wear the battery down completely. But Sony claims that the battery will last for up to 7,500 continuous page turns on one charge. Charge time is about 4 hrs. using ac power or 6 hrs. through USB.

The Li-Ion battery is mounted to the back of the display, which I thought was a little odd, and a tribute to the E Ink technology. I would have thought that the heat generated by the battery would distort the information on the display, but obviously not.

The processor that's inside the reader is not exactly state of the art. It's a Freescale DragonBall i.MXL applications processor, also known as the MX1 (or more specifically the MC9328MXL), that was designed around 2002. It was Freescale's first ARM-based processor, incorporating a 200-MHz ARM920T core. The core is surrounded by all the usual peripherals, like a UART, a memory interface, and a SPI interface. It's also got an integrated Memory Stick interface, which Sony took advantage of.

While the PRS-500 is fairly new to the U.S. market, it's been available in Japan for a number of years. That likely explains the use of the older microprocessor. Even though newer version of the i.MX family are available, Sony would have had to make changes to the software if they changed processors. Some of the software could likely have been re-used, but that would depend on which processor they chose to upgrade to. While a DSP would seem to be a likely choice for a CPU upgrade, that would require a significant change to the operating system stack.

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