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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  • groundhogdaze - Thursday, December 17, 2015 - link

    I'm wondering why there aren't more competing products? I definitely want one and I'm assuming there's a reasonably large market out there for this sort of device. I do own a kindle DX but the DPT-S1 would be so much nicer :)
  • JoeMonco - Thursday, December 17, 2015 - link

    Based on what evidence do you believe that there's a large market for such a device? The very lack of very many competing devices would prove just the opposite.
  • sungamer - Monday, December 21, 2015 - link

    Actually I think it's due to engineering problems. Large format e-ink displays are still difficult to make, and the fact is unless you're using a flexible system (such as Mobius used by Sony here) they're very much prone to breakage. Mobius is also very expensive (last I heard a 13.3 inch display would cost about $600, but I'm SURE that has come down a bit now), so the combination of price and engineering problems means that this category of products is at its infancy, rather than a lack of demand.
  • benzosaurus - Thursday, December 17, 2015 - link

    Speaking as an engineering student, I'd buy that thing in a heartbeat to replace my old iPad 2— if it cost, like, $100.
  • digiguy - Thursday, December 17, 2015 - link

    I had considered this but the price of over 1000$ was too much for something that can only display PDFs. Whats more, in Europe, it could only be bought from Japan, with menus in Japanese only. My ipad pro with similar size and aspect ratio, and a mat screen protector, can do much more for a similar price....
  • ganeshts - Thursday, December 17, 2015 - link

    Except that iPad Pro weighs a lot more and is bound to result in eye strain under continuous use.
  • melgross - Thursday, December 17, 2015 - link

    Yes. It does weigh more, but the eye strain concept is a lot of hooey. Billions of people use tablets and smartphones without getting eye strain. Billions more use laptops and desktops without having eye strain. The few that do get it are either sensitive to bright light, or simp,y have everything g adjusted improperly.

    Medical experts have already said that there's no difference to the eye with reflected or transmitted light screens. People who have the problem should either raise the brightness, or lower it, depending on how they have it set. It will make a difference.

    And a tablet, like the iPad Pro, or others, are just vastly more useful than something like this, particularly at the price point.
  • ganeshts - Thursday, December 17, 2015 - link

    All I can say is: Give an E-Ink device a try for a week and also repeat a similar workload with a carefully adjusted tablet / backlit display for a week, and you will be sure to feel the difference.

    Personally speaking, I tried reading a technical eBook on a tablet and also on the DPT-S1. I was able to read more pages in one go on the latter.
  • digiguy - Thursday, December 17, 2015 - link

    I really think it depends on what you read.... and how... First of all, I think a mat screen is a must. I really don't understand why people don't use them. All my tablets have a mat screen, including the Surface pro 3 (and the pen works perfectly). Then it's also a matter of adjusting brightness... Then there are books where colors are important and this device has no colors... As far as the weight is concerned, I think it depends. I never hold the ipad pro or surface pro 3 with just one hand vertically. Instead, the lower part is on my legs if I am sitting or, if I am standing, I hold it like a pizza. And it's not heavy at all like that. Now my main use was for sheet music. And for that weight is irrelevant. I wanted an A4 format, and Surface pro 3 was a bit smaller than ideal... Ipad pro is perfect, as close to A4 as it gets. Also for a large majority of my ebooks and scores 4:3 works better than 3:2. Now, I am not saying that weight and eye strain don't matter or that this device is not better on these 2 points, but that I believe there are workarounds that make then "less relevant". It's all a matter of trade offs. And at this price point this device means giving up a lot of what an ipad pro can do. Sure the price has come down, but this is IMO an already old device (thats probably why Sony paid for this review) that should probably be refreshed or upgraded and/or sold at a more reasonable price point....
  • ganeshts - Thursday, December 17, 2015 - link

    (thats probably why Sony paid for this review)

    whoa, dude! I paid $800 of my own money for this (Sony is not very liberal with review units unlike other manufacturers, btw) because I saw some value in it for my professional work as well as hobbies (solving crosswords and reading books). I thought AnandTech readers would like to hear the plus and minus points associated with the e-reader, and that is why I decided to write the review.

    This type of blanket statement surprises me greatly.

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