Foreign companies and inventors won nearly half the patents awarded by the United States last year, according to statistics released yesterday by the U.S. Patent and Trademark office.

Japan led the way with 19 percent of the 89,385 patents awarded in the United States in 1987, followed by West Germany with 9 percent, and France, Britain and Canada. In all, 46.6 percent of U.S. patents went to foreigners, up from 44.9 percent in 1986, marking the continuation of a trend that has seen the overseas share of American patents double over the past 20 years.

In announcing the figures, Patent Commissioner Donald J. Quigg chastised corporate America for "not keeping pace with the Japanese."

Last year, for the first time, the top three recipients of American patents were Japanese firms -- Canon Electronics, Hitachi Ltd. and Toshiba Corp. In 1986. Hitachi was first, bumping longstanding leader General Electric Co. into second place. Last year GE finished fourth.

"The Japanese have shown a talent for targeting a section of technology while U.S. industry plays a game of takeover and restructure," Quigg said.

The commissioner's views were shared by a number of economists and policy experts, many of whom have long pointed to the competition over patents as a significant measure of the United States' technological strength.

"This is yet another indicator that leads one to believe that our overall competitiveness as a nation is suffering," said Alan Magazine, president of the Washington-based Council on Competitiveness.

According to Herbert C. Wamsley, executive director of the Intellectual Property Owners, a patent owners' lobby group, "The feeling is that there is at least a rough correlation between the number of patents issued and the amount of technology being introduced."

But Wamsley also said that "you have to be cautious in how you interpret patent statistics," and a number of experts played down the relevance of yesterday's announcement.

"In and of itself I wouldn't be too concerned," said Robert Reich, a professor at Harvard University's Kennedy School of Government. "The U.S. continues to lead the world in new patents and Nobel laureates and other indices of inventiveness. Our real problem is that we don't get inventions from the laboratory to the workplace nearly as fast or as efficiently as our trade competitors do. These days new ideas developed in Cambridge can reach Seoul as fast as they reach Providence. The difference comes in how skillful is the work force in incorporating new ideas."

Reich added that "a lot of patents are defensive in nature. Companies may issue a wide variety of patents pertaining to roughly the same technology for the sake of frustrating any potential competitor. The abundance of patents doesn't mean that that company is more innovative."

Other experts attributed the large number of Japanese patents in part to differences in the Japanese and U.S. patent systems. The Japanese patent process grants far narrower patents -- permitting just one patentable claim per application -- than its American counterpart. The result, some analysts suspect, is that when those same or slightly amended applications are filed in the United States they are not as comprehensive as corresponding American patents.

That conclusion, however, is challenged by an analysis of Japanese technology to be published soon by the National Science Foundation. "Their patents may not be broad, but they have great technological significance," said Michael Albert, vice president of CHI Research, a New Jersey firm that conducted the NSF study. "These are the most often cited patents in the American system."