You'd think physician Peter V. Boesen would want his lawyers spending most of their time appealing his prison sentence.

Boesen, a Des Moines, Iowa, surgeon recently sentenced to 51 months in federal penitentiary for healthcare fraud, is suing Apple. He's alleging that the touch keyboard on the computer maker's iPhone PDA violates a patent he holds through a company called SP Technologies.

St. Petersburg, Fla.-based SP Technologies claims that "Apple has infringed, and is now infringing" its patent "through the use, sale, [and] offer for sale of its iPhone product and system," according to documents filed Thursday in U.S. District Court for Eastern Texas.

SP Technologies alleges that the iPhone's touch-based keyboard violates a patent the company received in 2004. The patent, filed under U.S. patent number 6,784,873 B1, describes a "method and medium for a computer readable keyboard display incapable of user termination" and lists Boesen as the inventor.

The company claims it dispatched a letter to Apple executives in February warning them that it believed the iPhone would violate its patent. "Apple failed to investigate, respond to the letter ... or take reasonable steps to avoid infringement," SP Technologies alleges in its complaint.

Civil court records show that Boesen, through SP Technologies, has filed a number of patent suits in the past, including claims against Canon, LG Electronics, and Kyocera. SP Technologies is seeking unspecified damages or royalties from Apple. Apple has yet to file a formal response to the claim.

Federal criminal records show that Boesen was sentenced to prison in May following a conviction on defrauding Iowa's Medicare and Medicaid programs by filing false claims. He was also ordered to repay the state and private insurers more than $900,000.

Boesen is free pending an appeal. No word on whether he is using an iPhone to text his lawyer.