how to check if an idea has been patented
There is no EASY way. If your invention is a new can opener, an existing patent for the same idea may never use the words can opener. For example, it may be described in broader terms: container de-sealer or metal wall scissor. The patent offices classification system helps a bit, but not much. Inventors tend not to want to find their invention, so, they type in --can opener-- and look at a few and say they couldn't find it. You have to look for it like you want to find it. try different search terms. when you find one thats close, look at the references cited in that application and look for other patents wherein the close one was cited.The Poor Man's Patent is a Myth
One of the undying myths of Patent World is that there is such a thing as a Poor Man's Patent. If you've never heard of it, the poor man's patent involves writing out a description of your invention and mailing that description to yourself. The transmission of this description through the mail and the cancelling of the postage by the Post Office is supposed to establish a date of invention for you. That way if someone steals your invention or comes along and invents it independently, you have "proof" that you invented it first. The proof is in the sealed envelop and the date the postage was cancelled.Utility patents
Utility patents are for either a: process, machine, article of manufacture, composition of matter or an improvement of any of the above. Patent protection is also available for (1) ornamental design of an article of manufacture (design patent) or (2) asexually reproduced plant varieties by design and plant patents (plant patent).Is my invention already patented?
Determine if your invention is novel by doing a "prior art" or patent search, find out if someone else has already patented your idea. An inventor or hired professional can conduct a search of the USPTO records.The Do-It-Yourself Patent Search
If you decide to do the patent search yourself, you have several search methods available: The USPTO (United States Patent Trade Office) Public Search Facility. The USPTO operates a Patent Public Search Facility located in Alexandria, Virginia. Here every U.S. patent granted since 1790 may be searched and examined. Many inventors like to make at least one pilgrimage to the Patent Public Search Facility. It's located fewer than 15 minutes from National Airport by taxi; Metro Rail serves it off the Blue and Yellow lines, King Street Station; and several hotels are within walking distance, so it's easy to get to and around.