eInk Doesn’t Use Power to Maintain an Image

August 11, 2010 at 5:00 am Chad Upton Leave a comment

By Chad Upton | Editor

eInk or electronic paper, is a modern display screen technology used in consumer electronics.

The most popular products that use electronic paper screens are eReaders such as the Amazon Kindle, Barnes and Noble Nook and Sony eReader.

When you first see an electronic paper display, the most striking thing is how much it looks like real paper. Not so much in texture, but definitely in readability. That’s because there really is an inky black dye inside the screen. Electronic paper displays are the perfect screen type for eReaders, for two main reasons.

Electrical charges repel particles, forcing the ink near top of screen where it appears black, or toward the bottom of the display where it appears white. This provides very sharp text, just like a real book. It also means the display reflects light the same way a real book does, rather than generate its own light like typical television and cell phone display technologies. This makes the electronic paper easy on the eyes over long periods of time and easy to read in sunlight.

The surprising thing about this technology is that is doesn’t use any energy to hold a static image on the screen — it only requires energy while drawing a new image on the screen. This is perfect for devices that don’t require the display to be updated constantly, such as eReaders. Even if you’re a very fast reader, it’s going to take you at least 10 seconds to read a page. That means you’re only using the battery for a fraction of a second to update the display and then the battery can mostly rest until the next page turn.

That is great, because it means the battery last for a very long time. It also means that the display shows an image when the device is off and not consuming power. When the Kindle battery dies, it switches the screen to indicate the battery is dead. So, even though you can’t turn it on, you know exactly why.

One of the main drawbacks is that electronic paper is a black and white technology. Technically, color ePaper exists, but it is not in widespread use. Additionally, the screen refreshes slowly when compared to other display types, such as LCDs.

Slow refresh is no problem for eReaders, it can paint a new page on the screen faster than you can turn a page of a real paper book. But, it’s not good for devices that require motion graphics. Amazon is working on games and applications to run on the Kindle, similar to iPhone and BlackBerry apps. But, you won’t likely see any fast action games on electronic paper devices anytime soon.

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Sources: Wikipedia (Electronic Paper, Kindle)