An attempt by a middle-aged inventor to prove he came up with the idea of the Sony Walkman suffered a setback at the Court of Appeal in London yesterday.
Andreas Pavel, 51, is locked in a legal battle with the Sony Corporation over patent rights for the portable stereo. Launched in 1979, the Walkman has earned the Japanese electronics giant an estimated pounds 3bn in worldwide sales.
Mr Pavel has consistently claimed Sony infringed his patent, filed in 1977, for a "stereophonic reproduction system for personal wear".
His machine comprised a pair of headphones strapped to a bulky belt, attached to which was a small cassette player, amplifier, batteries and a storage pouch.
However, Sony argued the technology was obvious and not inventive, and in 1990 the Patent County Court ruled his claim was invalid.
Yesterday, Mr Pavel launching his appeal against the judgment and sought to amend his patent with a new definition of his design as being "suitable for attachment to a belt".
However, counsel for Sony and Toshiba, also contesting the application, argued that the amendment to a patent was "an indulgence, not a right". After 10 minutes of deliberation, Lord Justices Neill, Hobhouse and Aldous rejected the application and instructed Mr Pavel's counsel to proceed with the appeal against the 1990 ruling, which is expected to last eight days.
The cost of the legal action, estimated at more than pounds 1m, is likely to ruin Mr Pavel if he loses on appeal.
If the judgment goes against Sony, Mr Pavel, the youngest son of a wealthy German industrialist, stands to become a very rich man by qualifying for royalties of between 1 per cent and 5 per cent of Sony's Walkman sales in Britain, equivalent to pounds 100m.