Sony, Sanyo Electric, Exceed Perseverance Electronic and Lucky Light Electronics, have agreed to license patents owned by a Columbia University Professor that cover basic semiconductor technology used in Blu-ray video players. Last March, the U.S. International Trade Commission said it would launch an investigation into some companies including Sony and Nokia on possible patent infringements related to Blu-ray disc players, mobiles and other products.

The move was based on a complaint filed in February by Columbia University Professor Emeritus Gertrude Neumark Rothschild, who was seeking to block imports into the United States of a range of products that she said had been infringing her patent.

Dr Rothschild conducted "ground-breaking" research in the 1980s and 1990s into the electrical and optical properties of wide band-gap semiconductors. The research, the firm said, has proven pivotal in the development of short-wavelength emitting (blue/violet) diodes used in consumer electronics.

Rothschild was issued a US patent in 1993 that covers a method of producing wide band-gap semiconductors for LEDs and LDs in the blue/ultraviolet end of the spectrum. The portion of her work at issue in the ITC case focuses on using gallium nitride-based semiconductor material in LEDs and LDs.

Earlier this year, South Korea's Seoul Semiconductor Co Ltd, and Taiwan's Everlight Electronics Co Ltd signed agreements with Professor Rothschild.

Rothschild previously settled issues of infringement of her patents with Nichia, OSRAM, and Koninklijke Philips Electronics NV.