Patents are like two completely different documents glommed together. The first part is like an instruction manual for an invention — it’s usually pretty easy to understand, and you can sort of figure out what the invention is supposed to be about.
However, the second part is really where the action is — the claims. They’re usually listed near the end, right after the inventor writes “I claim…” Claims are a detailed, formal statement of exactly what the patent covers. That’s important, because a patent lets the owner stop somebody else from doing what’s in the claims. So whether you’re the owner or the “somebody else,” you need to know what you’re allowed to do and what you’re not. The claims will tell you.
Claims are written in an odd, formal language that has developed over the years to make it easier for patent attorneys, patent examiners and judges to agree on what something means. (They still don’t always agree, but things would be even worse if we didn’t have the special language!) In claim-speak, changing one word can make a huge difference — the difference between a patent that covers a lot, and a patent that hardly covers anything. So it’s important to make sure claims are correct: if it’s your patent, you want the claims to cover your invention, and if it’s somebody else’s patent, you want to make sure you’re not doing something that the patent owner could sue you for.
You can get a general idea of what the claims cover by treating them as a laundry list of things that must be in the invention, plus the way the things have to be hooked together. Hold the claims up next to the invention (or next to a knock-off that you want to use the patent to stop) and run down the list, making sure you can point to every item in the claim. If something is missing or connected differently, then that claim might not cover that product. If none of the claims matches the product, then that patent probably doesn’t cover that product.
Of course, when you start examining the details of a product and a patent, you’ll often find that there’s some gray area. It’s usually pretty easy to decide if there is “a square base plate having seven threaded holes,” but is that piece over there really “a means for accessing the locking mechanism?” Which pieces, exactly, are part of the locking mechanism, and if they’re part of that, can they also be part of something else?
These are the kinds of questions that patent attorneys spend their days thinking about, so if you need to find out those kinds of answers, contact Mersenne Law.