Toshiba is readying two 3D televisions that can produce images with the illusion of depth but don't require the user to wear glasses, it said Monday. It will launch the televisions in Japan in December. By dispensing with glasses, the TVs answer a key complaint of would-be buyers -- but they won't come cheap.

Toshiba will offer a 12-inch model and a 20-inch model. They'll cost around ¥ 120,000 (US$1,430) and ¥ 240,000 respectively. Toshiba didn't announce launch or pricing plans for markets outside of Japan. (A video of the new TVs is on YouTube.)

The company is waiting on larger screens before it launches the TVs outside of Japan, said Masaaki Oosumi, president of Toshiba's digital media network unit, at a news conference. Markets such as the U.S. demand televisions with screen sizes starting at about 40 inches, making these first models a little small.

The 20-inch model packs the Cell Broadband Engine, a version of the same processor found in Sony's PlayStation 3 console, that supports several advanced image processing features. Toshiba said these include the ability to convert conventional 2D images to quasi-3D images on-the-fly.

3D TVs can simulate depth because they deliver a slightly different image to each eye. In current 3D TVs, images for each eye are displayed rapidly one after the other. Filters in the glasses flash on and off in sync with the TV picture so the right eye sees one image and the left eye sees the next.

Toshiba's new TVs have a thin sheet of small lenses in front of the display.

Behind this lens screen is a custom-developed LCD (liquid crystal display) panel. Each screen has 8.29 million pixels -- four times the number of pixels in a conventional "full HD" television -- organized into groups of nine pixels of each color. The nine lenses split light from each bank of pixels and send it to nine points in front of the TV

If the viewer sits in one of these sweet spots they get the 3D illusion.

The nine spots should enable several family members to watch a 3D image at the same time.

The set-up means that despite the large number of pixels in the screen, the resulting picture seen in each of the nine spots is equivalent to a 720p high-definition image, said Toshiba.

Similar technology is used in Nintendo's recently announced 3DS handheld gaming device. The 3DS has a screen from Sharp and sends the image to just one spot -- something that isn't a problem with a handheld

Toshiba unveiled the new TVs on the eve of the Ceatec electronics show. At the event the company is also demonstrating the same glasses-less technology on a 56-inch prototype TV.

The need to wear special glasses has been a common complaint about early 3D televisions. The glasses are required for each viewer, they generally weigh more than a typical pair of eye glasses, and because they contain an electronic circuit, they also need to be regularly recharged.

Martyn Williams covers Japan and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com