A Tokyo-based computer software company plans to file a patent infringement suit against major mapmaking firms over technologies used to make electronic maps for car navigation systems, a company spokesman said Monday.

The company, Maruishi Digital, has argued that the Association of the Precise Survey & Applied Technology, which has 116 mapping-related companies as members, and the Geographical Survey Institute, the governmental body in charge of mapping, have infringed on its electronic mapping technologies over the years.

Maruishi Digital is a subsidiary of Maruishi Cycle Industries Ltd.

If the company sues, it is expected to send ripples through the electronic map market, now believed to be worth about 6 trillion yen. Electronic maps have been used widely in car navigation systems and computer programs in Japan.

Creating electronic maps had posed a major challenge until the early 1990s, as operators had to draw lines for maps manually, based on the outlines of roads and buildings from survey maps.

The breakthrough technologies, considered essential for making electronic maps, were developed by former Okinawa prefectural employee Kenji Nishiishigaki, 53, according to the company and other sources.

In 1992, Nishiishigaki applied for a patent for the electronic mapping technologies to scan lines from survey maps into computers. The patent was granted in 1998.

Major mapping companies, which appear to be dependent on the technologies, filed an appeal to the Japan Patent Office, but the office rejected it in March 2001.

When he won the patent, it was believed the basic principles of Nishiishigaki's technologies had been widely adopted by many mapping companies, according to cartographers.

Maruishi Digital later obtained the patent from Nishiishigaki.