A split from the norm: Sony unveils its twin-screen tablet that opens like a book - but will it take a bite out of Apple?
* Sony will also produce a conventional tablet as it aims to break the market
* S1 and S2 will use Google's Android 3.0 operating system
* Tablets will both be wi-fi and 3G/4G compatible
* Prices and release dates not revealed

Being able to carry your entire book collection has become a feature of tablet computers. But Sony has gone one further by making a device that folds open like one too.

Sony announced it is entering the tablet market dominated by Apple's iPad with not one, but two devices.

The tablets - called S1 and S2 - will use an operating system based on Google's Android 3.0.

And in what Sony hopes will provide a key selling point, the latter has two 5.5-inch displays that can be folded like a book. The S1 has a 9.4inch display.