Chinese computer maker Lenovo presented a new tablet device including a bracket-cum-handle allowing it to tilt and stand, which it billed as a "game-changing" innovation.

Hollywood actor Ashton Kutcher unveiled the Yoga Tablet at a Los Angeles event which had been shrouded in mystery, with teaser videos and social media hints tagged #betterway.

The device, which has 18 hours of battery life and goes on sale Wednesday, has three modes: hold, tilt and stand. A cylindrical hinge on one side can either be held, or opened to produce a stand, similar to the kick-stand on Microsoft's Surface tablet.

"Watching and discovering that people frequently use tablets in three main ways allowed us to break the mold on the current 'sea of sameness' designs," said Lenovo senior vice president Liu Jun, calling it "game-changing."

Teaser videos ahead of the event had included some suggesting that it could somehow be attached to furniture or household appliances, but the product appeared less radical.

"For this me is a risk," Kutcher said in a livestreamed event from Los Angeles, praising Lenovo for realising that "the risk is to be taken now because this is happening in the world now.

"They understand that they have to take risks and lead," added the "Two and a Half Men" actor, who is known as a tech investor, and who donned a "Lenovo product engineer" badge for the presentation.

The device comes in 8 and 10 inch models, priced at $249 and $299 respectively. An optional bluetooth keyboard is available for the larger model, which serves as a cover.

It enters a hugely crowded tablet market still dominated by Apples iPad, but with rivals including notably South Korea's Samsung vying to attract customers in the run-up the all important US holiday gift-buying season.