The e-reader market has lost some of its initial appeal due to the rapid rise in popularity of tablets and other similar mobile devices. However, 'tablets' with E-Ink screens continue to offer the best reading experience in terms of reducing eye strain as well as providing long battery life. E-Ink screens have not scaled well in size, with the 6" screen size being the most popular and economical choice. Products with bigger screen sizes such as the Kindle DX (9.7") have not enjoyed market success.

E-Ink - A Brief Background

We will not go into the technical details of E-Ink here, but it suffices for readers to know that E-Ink avoids the use of backlighting. Instead, it relies on reflection from ambient light for visibility. In the latter aspect, it is very close to real printed paper. The major downside is that the refresh rate of E-Ink screens is very slow and only the monochrome technology is mature enough for mass consumption in the e-reader market.

E-Ink screens have been trying to evolve in two different ways. On one hand, we have attempts being made to get some sort of color display with E-Ink characteristics. On the other hand, E-Ink is trying to bring out flexible displays as well as produce larger sized screens. While screens of up to 32" in size are available for digital signage purposes, the maximum size currently supported for direct-to-consumer sales is 13.3".

The Need for a 13.3" E-Reader

Most of our workload nowadays involves sitting in front of a computer monitor and/or staring at tablet/smartphone screens. It is common for people to experience eye fatigue due to these activities. Having used multiple tablets and phablets for content consumption, I realized that none of them fit the bill when it came to reading technical documents or annotating them for future reference. In addition, all these technical documents are typeset in either A4-sized (8.27" x 11.69") or US Letter-sized (8.5" x 11") pages. This ruled out usage of any of the large number of e-readers based on the 6" E-Ink platform. A4 and US Letter correspond to diagonals of 14.3" and 13.9" respectively. 13.3" with an aspect ratio of 4:3 is ideal for displaying documents typeset in either A4 or US Letter-sized pages.

The Sony DPT-S1 - A 13.3" E-Ink Device

Sony's Digital Paper System (DPT-S1) was launched in April 2014. It takes things to a whole new level by making use of a 13.3" E-Ink Mobius screen. It was launched with a price tag of $1100, and was quite unpalatable for the ordinary consumer. It comes with a stylus / pen for taking notes as well as PDF annotation, and business users are its main target.

Initially, my impression was that lower priced variants with the same screen would soon appear in the market and target the average e-reader. Unfortunately, we are at the end of 2015, and the Sony DPT-S1 remains the only E-Ink Mobius-based product that consumers can purchase in the market. A little bit of silver lining lies in the fact that Sony has steadily been bringing the price down (from $1100 at launch to $800 right now).

The Sony DPT-S1 comes in a nondescript box. The package consists of a quick start guide, the e-reader in a leather sleeve, the pen / stylus, three replacement tips for it along with a tool to aid in pulling out the old tips, and a 7.5W (5V @ 1.5A) USB charger with a USB to micro-USB cable. The gallery below provides high-resolution pictures of the various components.

As can be seen from the gallery above, the main reader is like a sheet of white paper surrounded by a thick bezel. The bottom bezel is slightly thicker to accommodate the navigation and context menu buttons at the center with the power button at the right corner. The power button is on a slanted panel and is not flush with the rest of the frame - this prevents accidental pressing of the power button during use.

The important aspects of any e-reader are the dimensions and the weight. While the unit as a whole comes in at 9.125" x 12.125", the viewable area / screen is 8" x 10.625" (corresponding to a diagonal size of 13.3"). Note that this needs to be compared to an A4 sheet (8.27" x 11.69") and a US Letter sheet (8.5" x 11"). The viewable area is slightly smaller than both of them, but definitely much better than the 9.7" E-Ink screensfor documents typeset with those page dimensions.

The weight of the reader alone is 355g, while the stylus/pen adds an extra 9g. Placed in the supplied sleeve, the complete package weighs in at 496g. All said, the unit is quite ergonomic to use - both in hand, as well as on a table. The screen has a pixel resolution of 1600 x 1200 and can display 16 levels of grayscale. It is likely that most use-cases for the DPT-S1 involve text-heavy documents. The DPI and color limitations are not much of a concern.

In the rest of the review, we will take a look at the hardware platform in detail and follow it up with a look at the software aspects before providing some concluding remarks.

Hardware Platform
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  • Denithor - Friday, December 18, 2015 - link

    I wasn't sure if he was referring to TinTin or Asterix. Both great memories from my childhood!!
  • Guspaz - Wednesday, December 23, 2015 - link

    Full-colour e-ink seems to be a long way off: their existing colour solution (Triton) just sticks colour filters in front of monochrome eInk, and looks terrible even in their marketing. They have a three-pigment solution called Spectra that doesn't look too bad, but it sacrifices grayscale to do it: each pixel can only do full black, full white, or full red. Doing full colour would likely require five pigments (CMYK and white), and it doesn't sound like that approach could do it.

    The closest we might ever get is a combination of Spectra with localized pigments, such that you have a pattern of pixels that include some black/white/cyan, some black/white/magenta, and some black/white/yellow: that would let you do full colour in a vaguely similar manner to how CMYK printing does.

    The problem is that, as far as I know, eInk has never made a display that is anything other than a single uniform sheet of eInk, meaning that the entire sheet is just tiny little granules (of random size, if you've ever seen a macro shot) that are smaller than individual pixels. Any pixel or segment structure on eInk screens comes purely from the active matrix grid they stick on it...
  • phoenix_rizzen - Tuesday, December 29, 2015 - link

    Mirasol would probably be a better alternative. Has similar properties to e-ink, only needing power to change pixel state, not to retain an image; doesn't use a backlight; etc. But in colour.
  • Shadowmaster625 - Thursday, December 17, 2015 - link

    So when will we have devices that can swtich between standard display and E-Ink modes?
  • pedjache - Thursday, December 17, 2015 - link

    I wouldn't hold my breath on such multi-mode display, but I wonder when do we see the first device incorporating both, in 10+ inch form factor. Like, you know, what Yotaphone1/2 does in a phone...
  • name99 - Thursday, December 17, 2015 - link

    That depends on the meaning of "device" and "switch" :-)

    If you're generous in your definitions, we have that today:
  • Murloc - Friday, December 18, 2015 - link

    that's pretty much impossible unless one of the screens is transparent and very thin.
  • Shadow7037932 - Thursday, December 17, 2015 - link

    Ouch, that price. If this was around $200-250, I'd strongly consider it since this has a stylus and I take a lot of notes at work. Currently, I use a Surface Pro 2 which works great, but this has much better battery life and works as a fine substitute for a paper notepad.
  • ironwing - Thursday, December 17, 2015 - link

    Can you provide a list of file formats the device can display? The review discusses pdf files exclusively.
  • ganeshts - Thursday, December 17, 2015 - link

    The device supports PDF only.

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