The guide acts much like a flattened-out fiberoptic cable. Light from the LEDs enters the edge and is reflected internally until it exits through optical features imprinted onto the guide.

Supplies up to eight weeks of usage with wireless off.

Four low-power LEDs provide illumination for the guide. Their brightness can be adjusted

The display is made up of millions of microscopic spheres sandwiched between electrodes. Within each sphere are positively charged white ink particles and negatively charged black ones. Applying a negative charge to the bottom electrode repels the black spheres to the top, making the screen appear black at that pixel. A positive charge moves the white ones to the top.

Better E-Reading in the Dark

Electronic readers aren’t all that exciting. They’re rectangular, their screens are black and white, and all can’t do much more than display text.

So how do you liven things up? For starters, Amazon and Barnes & Noble added lighting systems to their newest readers, the Kindle Paperwhite and the Nook Simple Touch, to make it easier for people to read in the dark.

In Amazon’s Kindle Paperwhite, four LEDs mounted on the bottom of the reader shoot light toward the surface of the display. Barnes & Noble’s lighting, called GlowLight, has a similar system with LEDs. Both these glowing e-book readers cost $120.

But will adding some lights be enough to prevent e-book readers from becoming an endangered species? The International Data Corporation, a research firm, said shipments of tablets, smartphones and PCs grew 27.1 percent from last year. However, e-book readers are losing momentum. In the United States, manufacturers sold nine million e-book readers this year, down from 15.5 million last year, according to Forrester Research.

So why would anyone still want a reader? Readers are still much cheaper than tablets in general; the cheapest Kindle costs $70, while the cheapest Kindle Fire tablet costs $160. And if all you want to do is read books, a dedicated reader is still the best device for the job, said Sarah Rotman Epps, a Forrester analyst.