Over a decade ago, e-readers were hailed as a disruptive  innovation, promising excellent energy efficiency and a natural viewing screen akin to physical paper. Instead of this occurring, the market determined that multi-purpose smartphones and tablets offered greater  flexibility and were therefore preferable. However, e-ink devices continued to evolve, offering unique features that are well worth considering. Find out if e-ink technology has what it takes to make it into your home.

What Exactly Is E-Ink?

The best way to understand the difference between e-ink and LCD/OLED screens is to think of the latter as active displays, whereas e-ink uses a passive screen. Also commonly called an e-paper screen, e-ink means that ink capsules change contrast when an electric charge is applied to them. This is why such a screen is called an e-ink—electronic ink. 

Ink capsules hold black, negatively charged particles. If the applied electric charge is negative, those black particles with the same negative charge are repelled to the top of the screen. This has the effect of producing a black dot at that specific part of the screen; when combined, the dots form either text or images. 

How Does E-Ink Work?

As you can see, e-ink technology relies on a binary reaction spurred by different electric charges, which is why it is also called a “bistable” technology. This is the key feature of e-ink screens because stability implies that once black ink particles are directed to their, they maintain their position. In other words, no additional electricity is needed to maintain whatever form they end up composing – text or image. 

This also means that bistable e-ink screens are not the emissive displays you find in standard LCD or OLED screens. Instead, e-ink displays are reflective because they don’t use a backlight, which constantly needs to draw energy from a source of electricity, to generate the display. This feature makes e-readers the most book-like devices in existence. By contrast, under sunlight, LCD screens are barely visible at all. 

E-ink screens become more visible because they are reflective, just as you would experience when reading a paper book in a brightly sunlit area. Being able to mimic the physical book-reading experience is an excellent asset for marketing, which is why Amazon’s most popular e-reader device is called Amazon Kindle Paperwhite. The Kobo series of readers is even better, with the Kobo Forma model leading the way in features and design.

The Kobo Forma from the Canadian firm Rakuten Kobo offers the best e-readers on the market.

What Are the Advantages?

If you are a bookworm, there is no better technological solution than getting an e-reader device. It is no secret that active, emissive screens cause greater eyestrain than reading from a piece of well-lit paper. They might even induce headaches, dry eyes, or blurred vision if you indulge in the digital world for too long. E-ink devices have no screen refresh rate or blue light emission to cause such trouble or disrupt the sleep cycle.

Even though they are just like looking at paper, e-readers are far more practical than physical books. Have you ever found yourself futilely twisting a thick book in your hand when changing body positions in bed? With e-readers, this hassle is completely removed from the equation, as they are all lightweight, thin devices that allow you to turn the page with the flick of a finger. 

Speaking of flipping pages, e-readers don’t use battery power when displaying content, only when the display is changed. Unless you use your device as an MP3 player, with integrated lighting for dark spaces, energy will only be expended when you view new content. This translates to dramatically increased battery life, with up to 36 times less battery drain. In practical terms, when going camping, you would be able to read a whole library’s worth of books without worrying about where to plug in the charger. 

What Are the Disadvantages?

You may have noticed that almost all e-ink devices come only in black and white. While this makes them ideal for enjoying a relaxed book-reading session no matter the lighting environment, much of today’s content comes in multimedia form. After all, social media platforms evolved to seamlessly embed both video and audio. Unfortunately, this is where the hard limits of e-ink technology come into play. 

The best way to understand e-ink’s inherent disadvantages is to grasp the extent to which the technology has developed thus far. Five types of e-ink screens have been engineered; while they have many variations, they are all based on certain principles and hard limits:

• One-pigment – representing the first generation of e-reader devices, they work exactly as explained in the previous section.
• Two-pigment – consisting of millions of microcapsules smaller than a human hair, they work the same way, except that white particles rather than black ones are negatively charged. Because they are so numerous and tiny, they offer far greater clarity and resolution, just as an LCD monitor is clearer if it has greater pixel density and a smaller pixel size.
• Three-pigment – named Spectra 3000, this e-ink display system adds red particles to the mix; they are positively charged, just like the black ones. However, microcups hold them instead of microcapsules. 
• Four-pigment – named Spectra 3100, this is the first foray into making a color-enabled e-reader device. In addition to red particles, it contains yellow ones, and both can change temperature ranges to give yellow or red shades. 
• Multi-pigment – called Advanced Colour ePaper (E Ink ACeP™), this was the first system developed to offer the full range of colours based on eight primary colours. It can be made with either microcapsule or microcup techniques. By combining four types of ink pigments – magenta, cyan, yellow, and white – that are all are present in every pixel of the screen, these devices, which debuted in 2016, are capable of driving next-generation colour e-ink screens. 

Only during the last year have quality colour e-readers began to emerge. Pocketbook InkPad Colour is an example, showcasing a bright future for energy-efficient e-reader devices. [Image source: PocketBook]

As you may have concluded, by relying on fixed pigments instead of active/emissive screens, e-ink displays do have certain limitations. While the colour issue seems to have been largely resolved with ACEP multi-pigment technology, e-ink devices still cannot display dynamic imagery like animations and videos.

Moreover, some ebook readers require an external lighting source if they are viewed in a dimmed environment. Many models have integrated lights for this purpose, but this causes battery drain at approximately the same rate as a regular tablet. At that point, one has to ask why multiple devices that must be charged at the same rate are needed, especially when only one device is capable of offering the latest movies, games, and apps. 

Conclusion

E-ink will always be a niche market, never penetrating deeper to replace tablets or smartphones. However, its main limitation – pigment display instead of emissive screen – is actually an advantage for those who need to replace hundreds of pounds of physical books with an elegant, thin, lightweight device with minuscule energy expenditure. 

While one can get accustomed to reading ebooks from a 6” smartphone screen, e-readers are a superior alternative for the specific purpose of reading text in bulk. This is especially true if you find yourself in a sunny or bright space in which LCD screens become completely useless. Likewise, with the advent of colourized e-reader models, the comic book industry can transition fully into digital form, lessening the carbon footprint needed to transport and process trees. 

Such devices may end up being the pinnacle of e-ink technology, but that doesn’t lessen their unique value proposition.