Canon and Toshiba have postponed the launch of a new kind of flat-screen TV because of patent and production problems. 

The surface-conduction electron-emitter display (SED) screens were supposed to debut in shops at the end of this year but will now be delayed again. No future date has been scheduled for the release of the 55in screens.

Flat panel TVs created using SED technology are claimed to be more energy efficient than existing models available in the marketplace.

Sony could now leapfrog the technology by getting its smaller 11in organic light-emitting diode (OLED) TVs to market first. 

The 3mm-thick OLED screens were expected to go into mass production two and a half years ago.

Canon and Toshiba have been developing their SED technology since 1999 and the launch had originally been delayed until July 2007. That date has now slipped to the end of 2007.

Canon blamed part of the delay on the falling price of flat-panel TVs and said it needed to improve the efficiency of its mass production facilities.

Canon is also in dispute over the patents for the SED technology with a company called Nano-Proprietary. 

In February a US District Court found against Canon for breaching a licensing agreement with Nano-Proprietary and the company is currently appealing that decision.