Sony Computer Entertainment Inc executives are pledging to appeal a judge's ruling that the company violated copyright law in the design of its popular PlayStation.

If the company loses that appeal, it will have to pay a US$90 million fine and buy a licence for the technology, or else stop selling the console, a force feedback control and some game titles.

US District Court Judge Claudia Wilken last week denied Sony's effort to dismiss the entire case, when she ruled that Sony had paid an "unreliable" witness $150,000 to give testimony that he had invented the technology first.

The lawsuit began in February 2002 when Immersion sued Microsoft and Sony for violating its copyright on handheld game controls that vibrate in time with action on the screen.

"Sony was trying to convince the judge there was newfound evidence to open the case back up and remand it to district court, on the grounds there was fraud committed by Immersion. The judge has now denied that claim," said Victor Viegas, president and chief executive officer of Immersion, which is based in San Jose, California.

A Sony spokeswoman said she could not comment on an ongoing court case.

The engineering term for tactile force feedback is haptic technology, and it is used in products such as medical training simulators, mobile phones and automotive and industrial controls. Immersion licenses the technology to companies, including cell-phone maker Samsung and vehicle manufacturers BMW Group, DaimlerChrysler, Rolls Royce and Volkswagen.

Haptic feedback is also crucial for adding a true sensory dimension to the simulated action of video games. Game platforms that use a licensed version of Immersion's technology in their joysticks or steering wheels include Apple and Nintendo.

Sony used haptic technology in its Dual Shock controller, released for the 1998 version of its PlayStation product. It has also used the technology for subsequent versions, including PlayStation 2 and the pending PlayStation 3, as well as on 44 published games for those platforms.

In July 2003, Microsoft agreed to an out-of-court settlement of Immersion's patent infringement case, allowing it to use haptic technology in its Xbox video game platform. But instead of joining Microsoft in a settlement, Sony decided to fight Immersion in court. That strategy has gone poorly for the company so far, according to court documents and a time line provided by Immersion.

"We have had only four lawsuits in the history of the company, and three of the four have signed licence agreements. The fourth is Sony," Viegas said.

In September 2004, a jury awarded Immersion $82 million in damages following a trial in the US District Court for the Northern District of California in Oakland. That amount later rose to $90 million to include court costs.

In March 2005, Judge Wilken banned Sony from selling any infringing product, including the consoles, Dual Shock controllers and the specific games for every version of PlayStation. She froze that injunction pending Sony's appeal.

The latest chapter began in July 2005, when Sony filed a separate motion to throw the case out of court, citing new evidence that Immersion had concealed copyright drawings by an inventor named Craig Thorner. That motion was denied last Wednesday, with Judge Wilken calling Thorner an unreliable witness whose court testimony had been swayed by a payment of $150,000 from Sony.

Sony's appeal of the original judgment remains outstanding.