Walt Johnson is like a fishing guide for Minnesota inventors.

In a vast pool of 8 million U.S. patents, the Hennepin County librarian helps inventors locate just the patents they need to determine if they've created something truly new. It's a free computer search service that Minnesota inventors would pay big bucks for if they sought the advice of a patent attorney.

Still, doing a patent search is a daunting task, even with the help of Johnson, 53, the patent and trademark depository librarian at the Central Library in downtown Minneapolis. Besides sifting through the 8 million U.S. patents granted since 1790, inventors are faced with about 247,000 new patents granted each year.

"The tricky part is determining where to start looking," said Johnson, who has been helping local inventors navigate the federal patent system for 18 years. Then there's the challenge of deciphering patent documents, which is "like reading another language," Johnson said.

"The people who come to me are independent inventors, because most companies have their own patent staffs," said Johnson, a patient, soft-spoken man who also teaches a free library class outlining the basics of a patent search. "Most of them have realistic ideas, although some are kind of far out."

A part-time inventor might be tempted to skip the sometimes arduous patent search. But that could be an expensive mistake. If an invention isn't really new, the U.S. Patent and Trademark Office will reject a patent application that probably cost the inventor $5,000 to $10,000 in patent office fees and legal costs, Johnson said.

But inventors don't have to search through musty documents anymore. The Hennepin County library, which has partnered with the U.S. Patent and Trademark Office since 1981, has access to the government's Virginia-based database of all existing patents. However, doing an effective computer search of so many patent records requires an understanding of the convoluted structure of the U.S. patent system -- and that's where Johnson comes in.

Kathy Stark of Stillwater, who is researching a planned patent application for her beverage-related invention, came to the library to save on legal fees. What she got in addition was an immense amount of help from Johnson.

"Walt is really why I come here now," Stark said. "He helped me by knowing the patent classifications so well, and by steering me in the right direction."

Johnson also advised her to write to the patent office for suggestions on how to whittle down the size of her patent search -- a suggestion that bore fruit.

"Once I found out from them which patents to look at, I was able to winnow the list myself," Stark said.

A typical electronic patent search can take a few weeks or months, and consists of narrowing a search through the patent office's topic headings, then searching the remaining patents for key words and concepts, Johnson said. Searching is complicated by the fact that an invention can be described many ways. The Etch-A-Sketch, patented in 1973, is described in the patent as a "tracing device." Men's pants suspenders, patented in 1894, are called a "garment clasp" in the patent.

"I always make clear that I can't do the search for them, but I can show them generic examples of how to do it," Johnson said. "I suggest that they use our service to test the feasibility of applying for a patent, but get a lawyer for the actual patent application. Applications are so finely worded that it's like writing a will; if it's not worded just right you can lose patent protection."

A valuable service

Dan McDonald, a patent attorney at the Minneapolis law firm of Merchant & Gould, said the library's patent search service is valuable for inventors.

"I think the library searching is a great first step," McDonald said. "An inventor can get a sense of what's out there before spending any money. But I would still encourage an inventor to talk to a patent attorney. The attorney may say they've done a great job of searching existing patents, or tell them they need to do some more work." Only about half of all patent applications are granted by the patent office, he said.

Rather than use the library's service, Merchant & Gould outsources patent searching to firms in Washington that typically charge $500 to $1,000 for a search of not only existing patents but other published documents, such as research papers, that may bear on whether a Twin Cities invention is patentable, McDonald said.

Johnson said the public library can search only patents, not other published documents about new discoveries. Even so, the amount of information the library has is so immense that there's a danger of would-be inventors becoming discouraged.

Johnson's advice: "Be patient, and don't have any get-rich-quick expectations. And have faith in your ideas."

Steve Alexander • 612-673-4553