1. Each claim of a patent is an AND statement, or if you like, an infringement checklist: If even one element in a given claim is missing from the accused product or process---and is not present by a "substantial equivalent" either---then that claim is not infringed.
2. In determining infringement, the different independent claims of a patent are OR'd together---only one of them need be infringed for the defendant to be liable.
3. A patent claim is invalid it if returns TRUE on the prior art, or on something that would have been "obvious" in view of the prior art at the time of the invention. How to determine obviousness in hindsight is perhaps the big question of patent law.
4. The claims of a patent are like a salvo of cruise missiles. The patent owner will launch as many claims as it can against a purported infringer. Some claims will miss, that is, they simply aren't infringed. Some claims will be knocked down by defensive fire, that is, by proof of invalidity. If even one claim gets through to the target, the patent owner is entitled to damages and (quite possibly) an injunction against further infringement.
If you'll pardon the self-reference, I wrote up a description of how patent claims work at http://www.ontechnologylaw.com/how-patent-claims-work-a-vari....
In a nutshell:
1. Each claim of a patent is an AND statement, or if you like, an infringement checklist: If even one element in a given claim is missing from the accused product or process---and is not present by a "substantial equivalent" either---then that claim is not infringed.
2. In determining infringement, the different independent claims of a patent are OR'd together---only one of them need be infringed for the defendant to be liable.
3. A patent claim is invalid it if returns TRUE on the prior art, or on something that would have been "obvious" in view of the prior art at the time of the invention. How to determine obviousness in hindsight is perhaps the big question of patent law.
4. The claims of a patent are like a salvo of cruise missiles. The patent owner will launch as many claims as it can against a purported infringer. Some claims will miss, that is, they simply aren't infringed. Some claims will be knocked down by defensive fire, that is, by proof of invalidity. If even one claim gets through to the target, the patent owner is entitled to damages and (quite possibly) an injunction against further infringement.