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What’s the difference between a tablet and a dedicated e-reader? And what should you look for in an e-reader?
The American e-reader market oversaturated itself with locked down Kindle Fires, Nooks and Kobos (read our reviews of the Fire HDX, Kobo Aura HD, and Kobo Arc). For inexplicable reasons, major manufacturers hobbled their wares with barriers. Innovative features were ignored, or hidden, such as 8-inch E-Ink screens or access to vanilla Android. Larger screen sizes allow for ebooks to read like paper books. Android enables the Play Store, the Amazon App Store and more, with their myriad number of applications and customizable features. The locked down experience offered by Amazon, Kobo and the Nook severely limits utility, and value, to consumers. These shortcomings led to the current market dominance of the faster and more flexible tablets.
Six features differentiate an e-reader from a tablet: The display technology, the touchscreen technology, the operating system, applications and hardware. Pay careful attention to the display and touchscreen technology, as these two features differentiate a tablet from an e-reader.
Screens, Touch Technology and Software
E-readers never really caught on in the United States, the way they did in Europe. In America, most users prefer emittive LED backlit LCD screens over “reflective” screens, which emulate the experience of paper. For example, emittive screens show up in the majority of e-readers, including the Amazon Fire.
Five different touchscreen display technologies exist, although only two see any use:
- Resistive: Resistive screens measure pressure. Most early tablets and smartphones used resistive touchscreens, but the technology suffers from relatively low operational longevity. Ironically, resistive screens provide superior impact durability and element resistance to other screen technologies.
- Capacitive: Most tablets use capacitive screens. The technology registers screen touches by running a low current through any object that touches its surface. Non-conductive objects won’t trigger the screen. On the downside, capacitive screens have less clarity than other technologies, because of a thin layer of conductive material.
- Infrared: Infrared touchscreens offer the best solution for e-readers. Neonode is the only company, to my knowledge, producing infrared touchscreens. IR requires a larger bezel, but it overlays no material over the screen itself, resulting in unimpaired screen clarity. Although screen fouling issues can cause IR to malfunction, it’s inherently more durable than capacitive, as it works even after a screen suffers physical damage.
- Surface acoustic wave: SAW screens are motion/resonance sensitive. While they offer most of the advantages of IR touchscreens, and few of the shortcomings of capacitive, they aren’t used on many e-readers – I could not find any device that relied on wave/resonance technology. But if you do see a device with a SAW screen, it’s worth looking into for its advantages.
- Electromagnetic: These screens require a special magnetic stylus to use. Unfortunately, fingers won’t trigger an electromagnetic screen. To my knowledge, only the Onyx M92 and M96 e-readers include electromagnetic touchscreens.
Summary: Of the available tech on today’s e-reader market, Neonode designed IR screens make for the best e-readers. There exist other proprietary technologies, such as Hanvon’s ERT Touch, but these don’t exist in US markets.
As mentioned previously, two kinds of e-reader displays exist – emittive and reflective. Emittive screens emit light, examples include backlit LCD screens found in the Kindle Fire and upcoming Samsung Galaxy Nook. A reflective screen bounces ambient light off its surface, meaning their surfaces aren’t visible in a dark room. Of the screens presented here, any device with a “reflective” screen enjoys weeks, or months, of battery life. Emittive screens provide mere hours.
Emittive Screen Technologies
- AMOLED: AMOLED produces the least amount of eyestrain out of the major emittive screen technologies. Each pixel on an AMOLED screen emits a color, rather than using a backlight combined with a substrate of pixels with varying colors. This results in better contrast between dark and light pixels and better image quality – to some extent. I haven’t heard of an e-reader that uses AMOLED screen technology yet, but it would be very welcome (pictured below).
- LCD: These screens use a substrate of pixels and an LED backlight. The source of the light is actually the backlight and it’s the substrate that colors the emitted light.
Reflective Screen Technologies
E-paper: E-paper reflects ambient light, which reduces eye-strain. It suffers from a low refresh rate, and jarring page turns. While e-paper can technically refresh at speeds capable of producing video (referred to as A2 mode), it loses a great deal of screen quality while doing so. All major e-readers inexplicably disable or ignore A2 mode. However, because the technology doesn’t require constant screen refreshes, devices with e-paper offer battery life spanning months, rather than hours. It’s commonly known by its trade name “E-Ink”.
Mirasol: Qualcomm’s Mirasol display technology, also known as interferometric modulator display (IMOD), generates colors by using tiny mirrors to interfere with reflected light. The most recent variations on the Mirasol technology can produce framerates of up to 40fps. Unfortunately, Qualcomm hasn’t committed to producing any e-readers. The previous readers based on Mirasol were dismal failures – such a limited run made by Kyobo. You can see a video of it below:
Color e-paper: E-Ink produces several lines of color display. Some only display red, in addition to black and white. Others, such as their Triton series of e-paper display, include a full range of colors, but at diminished resolutions. Only a handful of color e-readers were ever produced and these tended to suffer from washed out colors, lower resolutions and weak support. You can see video of the Triton 2 below:
Liquavista: Amazon recently acquired Liquavista from Samsung. Liquavista’s technology employs electrowetting, which uses an electrical field to manipulate liquids. Liquavista’s display technology is daylight readable and uses very little power. You can see video of Liquavista’s technology below:
Summary: There are a lot more technologies out there. In particular, full-motion, color screens. Unfortunately, due to a lack of consumer demand – most consumers don’t like the either lower resolution (800 x 600) or the slightly silvered colors of color E-Ink screens – this hasn’t caught on in a big way yet. A handful of color e-readers exist, which because of low consumer demand, cost a fortune.
I’ve written before about the upcoming E-Ink (or similar technologies) that were slated for release. Many of them didn’t pan out, unfortunately, but they are worth looking at.
Available Operating Systems
- Android: Most e-readers use forks, or custom modifications, of Android. Android itself derives itself from Linux and essentially operates as a platform for running Java applications. Most e-readers use Android 2.1 to 2.3 as a basis for development, then apply a custom skin and deny access to the Play Store. The latest version of Android to see use is Android 4.0, Jelly Bean. To my knowledge, only Onyx manufactures tablets with Jelly Bean. Vanilla Android, without restrictions, can be found on Onyx devices.
- Linux: Other e-readers base themselves on Linux. These examples typically include custom software for reading an organizing mobile book formats, such as MOBI, ePUB and PDF. Because they use an ARM-based chipset, they can only use Linux software compiled specifically for ARM devices.
- iOS: One might make the argument that iOS devices can dual-operate as e-readers. With access to the iTunes Store, the iOS ebook depository rivals the Android ecosystem. Unfortunately, the screens all use capacitive and emittive technologies. They can operate as e-readers, but these are tablets masquerading as e-readers.
Summary: Android e-readers offer the largest app depository, unless they’re locked down, like the Nook or Kindle. iOS would offer an excellent alternative, if Apple didn’t lock their operating system into a narrow array of devices. Apple customers can’t get technologies other than capacitive touchscreens and LCD screens. Overall, consumers get better value from unlocked Android devices, which can install all reader apps.
Ultimately, you want an e-reader that can handle major mobile formats. Tablets excel at this, as they can install a variety of reading applications. EZPDF is an example of a reading app that handles most major format and installs on a variety of systems, primarily Android and iOS.
Android tablets can access three major marketplaces: The Amazon App Store, the Google Play Store and to a lesser extent, the Kobo app. There’s also the lesser known Good eReader app store. If you can access the Play Store, you automatically receive access to the libraries at the Amazon App Store and through the Kobo app.
Many e-readers are locked into either the Amazon App Store or Kobo’s library. The best option is Play Store access. Linux-based e-readers can only access the libraries that their provider equips the device with.
Linux at one point had access to OpenInkpot, an open-source distribution for eBook reading devices. Unfortunately, it fell into disuse and is no longer maintained. I’m sure other distributions and softwares for Linux exist, but I could not locate them.
Virtually all e-readers use extremely weak chipsets. To date, all e-readers use single-core processors, with a maximum speed of 1GHz. They oftentimes throw in between 128MB and 1GB of RAM. Overall, a dedicated e-reader doesn’t need powerful specs. I’ve actually underclocked my rooted Nook Simple Touch to 300MHz which dramatically improves its battery life without punishing performance.
Overall, e-readers don’t need powerful specifications. However, some tablets offer a switchable backlight, for reading in the dark — for example, the Kindle Paperwhite. In fact, most of the modern e-paper tablets include some kind of backlight support. Another hardware feature that you may find, very rarely, is E-Ink’s A2 mode. A2 mode allows for video to display on E-Ink, screens, with some degradation in picture quality. However, manufacturers like Onyx make A2 controllable with a hardware button. The advantage of A2 mode allows E-Ink screens (or e-paper, same thing) to function as tablets, or to provide smooth page scrolling. Here’s an example of A2 mode in action (WARNING! Your mind may get blown):
Conclusion: Tips for Buying an E-Reader
So what should you look for? Prospective buyers can boil down what makes an e-reader to just a few key points:
- Battery life: If you’re interested in battery life, look at the screen technology. If it’s emittive, you will likely get hours of battery life. If it’s reflective, you will get weeks, if not months.
- Screen size: Do you need a larger e-ink screen? Overseas manufacturers make a variety of 7, 8 and 9-inch E-Ink e-readers. The upcoming Onyx Boox i86 includes an 8.6″ E-Ink screen.
- App libraries: Do you need access to Google’s Play Store and Amazon’s App Store – or just one of the two? If you want both, you’ll need full Android. If just the Amazon App Store, you may want to consider an Amazon Fire (which uses an emittive screen).
- DRM (digital rights management): Do you need to “sideload” a number of PDFs or other digital format ebooks? Consider a device offering full, vanilla Android.
- Eye strain: Do you value screen clarity and want to avoid eye-strain? Look for tablets offering E-Ink or other reflective technologies.
- Annotations: Want to make annotations on PDFs using a stylus? Look for the electromagnetic touch touchscreen technology.
- E-paper as a tablet: If you want to use your e-reader as a tablet, look at whether or not you can enable full Android. For example, the Kobo Aura HD can be modified to support full-Android.
When you buy an e-reader, take a close look at its screen and touchscreen technologies. The two combined can allow for a paper-like viewing experience and months of battery life. If you need a more full-featured device and don’t mind eye-strain or a short battery, you may prefer a tablet. It’s somewhat disingenuous of Amazon to sell the Kindle Fire as a dedicated e-reader, since it offers similar specifications as a Nexus 7, but without access to the larger Android app ecosystem.