Thursday, July 23, 2015

The Evolution of Front-Lit e-Reader Displays


The vast majority of e-readers on the market pack technology that allows you to read in the dark. Unlike a smartphone or tablet that have light that shines into your eyes, front-lit displays have five LED lights built into the bottom of the bezel that project light upwards. How does this technology really work? Today Good e-Reader investigates.

e-Readers first became popular in 2007 when Amazon released the first generation Kindle. This e-reader and all others that came after it, use technology from e-ink, called e-paper. E-paper displays have advantages such as a pleasant reading experience, extremely low power-consumption and provide users with the ability to read in sunlight. Because it is reflective it just gets brighter when you sit in a brighter environment – for example outside. But e-paper displays – like real paper – are impossible to use in a dimly lit room or during a flight when lights are out.


This all changed in 2008 when Sony unveiled front-lit technology for the first time with the advent of the PRS-700. It incorporated LED lights on the side of the bezel that projected light across the screen. Because this technology was so new, Sony did not implement it properly and the end user experience was a pale blue hue, and was not very indicative of a quality reading experience. This device also did not sell very well, because of the $400 price tag. Sony had such a negative outcry from their growing base of e-reader owners that it vowed never again to include light in any of their future devices.

Nook Simple Touch with Glowlight on the Left, Kobo Glo on the Right

Nook Simple Touch with Glowlight on the Left, Kobo Glo on the Right

It wasn’t until 2012 that the next e-reader had a front-lit display and it was the Barnes and Noble Simple Touch with Glowlight. The nations largest bookseller was trying everything they could possibly do to differentiate themselves from Amazon, Kobo and Sony.

When this device first came out Barnes & Noble said that the GlowLight technology was designed in-house at the company’s office in Palo Alto, Calif., and has a patent pending. Instead of having the light on the sides of the bezel, like the Sony model did, B&N included five LED lights on the top of the bezel, that projected light downwards. You activate the light by holding down the Nook button on the front and shut it off the same way. You can also dim the light to avoid bothering a bed partner who’s trying to sleep.

Later on in 2012 Amazon and Kobo both got into the front-lit game with the Kobo Glo and Amazon Kindle Paperwhite. These two companies refined what Barnes and Noble did, by including the LED lights on the bottom of the bezel, and projected light upwards. This was a winning formula and something all future e-readers adopted going forward.

Amazon finally got Light Right


The Amazon Kindle Paperwhite got light right. All prior models had a noticeable blue hue to the screen, and this was something nobody could figure out until the folks at LAB126 figured it out.

Amazon has not revealed exactly how (because it is patented) but broadly speaking it works by using a light guide layer that is located underneath the anti-glare layer. The LEDs (light emitting diodes) are placed at one of the edges and light is then guided out on the light guide layer and down from the top into the e-paper display with the use of a light diffuser. The light diffuser's purpose is to distribute light evenly on the screen which is done by having tiny holes in the layer. Closest to the LED source the holes are farther away and further away from the light source the tiny holes are more concentrated. This is necessary because the LEDs are placed at one edge only.


Previous generations of the Kindle used an infrared touch technology where infrared sensors where placed at the edge of the bezel. Infrared touch technology is far slower and more inaccurate. The Kindle Paperwhite was the first Amazon branded e-reader to feature a capacitive touchscreen display, which warranted a different way to approach the lighting system. This is more or less why Amazon currently leads the pack because most of the industry still uses infrared lighting (Kobo Glo HD, Nook Glowlight etc).

Front-Lit Displays – a closely guarded secret

Amazon, Barnes and Noble and Kobo all have different ways of approaching front-lit displays and they all have their own patents for the technology. Not a single one of them would speak on the record about the evolutionary growth of their LED lighting systems and what has changed from the first model to include LED lights to the latest and greatest. Not even e-Ink, the company responsible for developing e-paper displays and controllers would speak about it. 3rd party manufacturers that churn out whitelabel e-readers that companies like Onyx, Pocketbook and Icarus would also not comment.

Why is front-lit displays such a closely guarded secret in the industry? Nobody really knows and the companies involved in the development space keep this close to the vest. This is honestly so weird, I have been covering e-readers since 2008 and I know everything about the hardware. From who makes the RAM and processors to batteries. Who makes front-lit displays? How many different generations have passed from the first to the current? These are questions nobody will answer, either on or off the record.

After careful analyzation there has been a few major benchmarks or generations of front-light. The first was the Sony PRS-700, the second was the Nook Simple Touch with Glowlight, the 3rd was the Kindle Paperwhite and the 4th is what is on the market today.

Check out for yourselves how lighting on e-readers has changed.

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