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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  • ganeshts - Thursday, December 17, 2015 - link

    The writing part is pretty much instantaneous - not that different from writing on paper (I assume some software is involved to refresh only that area of the screen, as whole page refreshes do take up the long time customary in E-Ink devices).

    However, the writing aspects needs some getting used to. Additional calibration is necessary to adapt to each user's writing style.
  • ddriver - Thursday, December 17, 2015 - link

    Previous generations have had problem with partial updates - the "pixels" at the rectangle area showed visible artifacting, so the whole screen had to be updated for the sake of uniformity. Maybe this is finally resolved?

    At any rate, I think people would rather take a video of the response time rather than someone's word, weighted by someone's standards for latency. The same applies for noise testing - dB is not all, and different frequencies are perceived at different levels at the same sound pressure. Any particular reason AT reviews don't include video and sound samples?
  • ganeshts - Thursday, December 17, 2015 - link

    Sure.. the folks at Goodereader have taken a lot of effort in their coverage of the Sony DPT-S1. You can take a look at one of their videos linked below (the writing process on the Sony DPT-S1 starts around 3:30 onwards)

    As for our reviews including video and sound samples - it all depends on the device being reviewed, and the amount of effort / time that we can allot to a particular review. Sites like GoodEReader dedicate themselves to covering one particular area in detail. We cover a wide variety of products and try to give details in as much depth as possible within the time constraints.
  • ddriver - Thursday, December 17, 2015 - link

    It looks adequately responsive. I suppose the trickery involved is not even using a rectangle area for the refresh, but going down to the individual pixels, potentially masking the artifacts.

    You know what they say - a picture is worth a thousand words. And a video is worth a thousand pictures. Therefore, a video is worth a million words ;)
  • moozooh - Friday, December 18, 2015 - link

    E-ink screens have several modes of screen update (IIRC YotaPhone's programmers used at least four of them) which dictate the overall refresh rate, color depth, and artifacts (in the form of high-frequency noise and ghosting, i.e. residual afterimage). Tight mode control can work wonders.
  • DanNeely - Thursday, December 17, 2015 - link

    Looking at the buttons on the device, I have to ask: Is it running generic linux; or a heavily customized Android fork? I know there've been a few Android/EInk devices made by small tier companies over the last few years; so I know it's technically possible, but an entry by Sony would give much more credibility to such implementations.
  • ganeshts - Thursday, December 17, 2015 - link

    I think it is a heavily customized Android fork since there are some Chinese sites offering rooting for this device and allowing installation of external Android apps. Obviously, nothing that I can confirm - so I just left it at 'Linux kernel' in the article.
  • Murloc - Friday, December 18, 2015 - link

    I have a much older sony reader e-reader and it's a heavily modified Android fork.

    You can indeed root my reader too and play angry birds on it, I saw a video of that.
  • haukionkannel - Thursday, December 17, 2015 - link

    Interesting device! Make it a little lighter and make it with bigger memory, it would be ideal e-book / A4 document replacement.
    Just have to hope that there will be somewhat cheaper alternatives in the future though. I really would like to have it, but when weighting what else can be get with 800$...
  • nico_mach - Thursday, December 17, 2015 - link

    It's such a crazy device and I'm soooo glad someone reviewed it.

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