Seattle engineer Conrad Gardner has sued Toyota Motor Corp., alleging that the giant Japanese auto manufacturer infringed on a patent for hybrid technology that is now used in the Prius, Camry and Highlander.

A 75-year-old inventor and former patent attorney at Boeing, Gardner argues that the hybrid vehicles produced by Toyota could not operate without his invention. U.S. Patent 7,290,627 -- dubbed "Extended range motor vehicle having ambient pollutant processing" -- is a computer control system that shifts power to the internal combustion engine or electric motor. (Full complaint here.)

"I just want them to respect the patents of others," said Gardner when asked what he hoped to gain from the lawsuit. "I am trying to teach them a lesson, you might say. That a small fellow, an independent inventor, is going to stand up for his rights. That's all."

The patent dates back to a filing in 1992, two years before Toyota attempted to patent a similar system. It was not issued until last fall, partly because Gardner said the patent office misplaced the application. The complaint -- filed today in U.S. District Court in Seattle -- notes that the U.S. Patent Office rejected Toyota's patent application for hybrid vehicle technology in 1994 because of Gardner's pending claim.

Toyota started the Prius project for the U.S. in late 1995, with the first vehicles introduced in 1997, according to the complaint.

Gardner is asking for a temporary restraining order to prevent Toyota from manufacturing any of the hybrid vehicles. He is also asking the court to permanently stop the manufacturing unless they enter into a licensing agreement, which he has attempted to strike with the company in the past.

Toyota spokesman Xavier Dominicis had not seen the complaint, though he said the company typically does not comment on pending litigation. The company has faced other suits related to its hybrid system, including one by Solomon Technologies. (More on that from AutoblogGreen.)

"As a general rule, these things don't stand the test," said Dominicis. "It is a very litigious world and on any given day any automaker will have a dozen suits on one thing or another."

Gardner said he has attempted to "reach a peaceful solution" with Toyota over the past two years, but the talks have been greeted with "a lot of nonsense."

A former examiner in the U.S. Patent Office, Gardner said sometimes you have to sue a large corporation in order to get its attention.

He said he is not concerned about the prospects of litigating the patent issue with the world's largest car maker.