The company behind the BlackBerry has been showing off a new tablet device set to launch in early 2011.

Research in Motion Limited (RIM) is betting on a smaller, lighter device than Apple's iPad, which kicked-started the tablet market when it launched in April.

The PlayBook will have a seven-inch screen, making it half the size of the iPad. And unlike the iPad, it will have two cameras, front and back.

RIM didn't say what it would cost, but said it would be in the same range as the iPad, which starts at $499 US dollars.

The PlayBook will be able to act as a second, larger screen for a BlackBerry phone, through a secure short-range wireless link.

When the connection is severed - perhaps because the user walks away with the phone - no sensitive data like company e-mails are left on the tablet.

Outside of Wi-Fi range, it will be able to pick up cellular service to access the Web by linking to a BlackBerry. The tablet will also work as a standalone device.

RIM co-Chief Executive Jim Balsillie said its goal is to present the full Web experience of a computer, including the ability to display Flash, Adobe Systems Inc.'s format for video and interactive material on the Web.