A Tipperary man has won a prestigious award in the United States, and has been named as Silicon Valley's "Inventor of the Year" for 1997. Mr John Ryan, the founder of Macrovision, beat off competition from top engineers in the electronics sector, taking the award for his devices designed to prevent copying of rented video cassettes.

The modest, 51-year-old Mr Ryan, whose invention is now used in 1.4 billion video cassettes in the US alone, said he was flattered by the award.

Mr Ryan's inventions - he has some 35 patents - centre on the prevention of video cassette piracy. The products based on these, made by Macrovision, prevent illegal copying of rented video cassettes. The company controls virtually 100 per cent of the market.

"What our product does is fool the VCR into making a very poor copy of the video," Mr Ryan said. "The image on the copy will go from being very bright to very dim every 20 seconds or so."

This effect is created by use of an electronic circuit in every video recorder, the automatic gain control, which automatically adjusts the signal strength to the optimum level.

Although it can be circumvented by professional video pirates, the device effectively eliminates casual copying. Mr Ryan's invention is in almost all cassettes made by Disney, Paramount, MCA-Universal, Fox and CIC, all over the world.

A native of Tipperary town, Mr Ryan got his start in electronics as a technician for RTE television in 1966. In 1968, he moved to Yorkshire Television as a research engineer, moving to California in 1974 to work for International Video Corporation. Two years later he moved to Ampex as director of research and development.

"In 1983, in the time-honoured tradition of Silicon Valley, I left Ampex and started my own company," he said.

In March, Macrovision floated on New York's Nasdaq stock exchange, and its share price has risen steadily since from its initial price of $9. Yesterday, the stock was trading at over $14.

The company, which has some 80 employees and is based in California's Silicon Valley, had annual sales last year of $17 million (£11.5 million), 20 per cent up on the previous year.

It first quarter results this year show net income from continuing operations up by 187 per cent on the same period in 1996, at $554,000. Net revenues for the quarter rose by 27.4 per cent, to $4.6 million.