Apple, Samsung and SanDisk have been sued by Texas MP3 Technologies which bought the US patent from two Korean inventors. The patent was originally lodged in 1997, was bought by Texas MP3 on 15th February of this year, and the suit was filed on 16th February.
The patent makes broad claims, saying that it covers technology which is a "portable audio device suitable for reproducing MPEG encoded data includes a plurality of inputs, a data storage, a display, an audio output, at least one processor and a battery".
The claim has been filed in a Texas district court by the company, which operates out of a Texas post office box. Eastern Texas courts are regarded as being sympathetic to patent holders and are often the chosen forum for disputes.
The suit claim that the named companies wilfully violate the patents. Wilful violation carries a stiffer penalty than simple violation.
The patent was sold by SigmaTel to a patent licensing company last summer, though it is not clear whether or not that body was Texas MP3. Chief executive Ron Edgerton explained the company's rationale last July.
"We made this decision because this patent may require millions of dollars of legal fees to optimize its value, and otherwise would have required a significant amount of SigmaTel’s management attention," he said. "SigmaTel’s customers, however, will not have to worry about this patent being enforced against them, as SigmaTel has retained the necessary rights to protect its customers."
The case has come to light just days after Microsoft was ordered to pay $1.5 billion in a separate MP3 patent case. Alcatel-Lucent had claimed that Microsoft's use of MP3 encoding technology violated patents it had long held in the area.
Microsoft said that a licence it has from German firm Fraunhofer-Gesellschaft entitled it to incorporate MP3 encoding in its Windows operating system. Alcatel-Lucent claimed that its Bell Labs subsidiary owns patents on the technology.