Sony has officially launched its electronic book, the Sony Reader. The device has a 15cm display and can hold up to 80 standard books. A memory stick and SD card slot allow more to be added. 

The Reader weighs about 250g, is less than 2cm thick and will go on sale in the spring at an expected price of £200-£300. It has a headphone jack and can function as a media player for MP3 files.

"In recent years millions of people have become comfortable downloading and enjoying digital media, including electronic books. But until now, there has not been a good device on which to read them," said Ron Hawkins, senior vice president of personal reader systems marketing at Sony Electronics.

"Our research has shown that people are looking for a device designed exclusively for immersive reading. The Sony Reader, with its electronic paper display, thin format and extraordinary battery life, fits the bill."

Battery life is key to such a device and Sony is using screen technology from US firm E-Ink to offer at least 7,500 page turns between recharging.

The screen uses tiny rotating spheres, half black and half white, which switch and lock to eliminate screen flicker and allow substantial power savings.  

Many of the world's leading book publishers will support Sony's device, including Random House, HarperCollins, Penguin Putnam, Simon & Schuster and Time Warner Book Group.

One of the first books to be available is Dan Brown's bestseller The DaVinci Code.