For an invention to be patentable, it must be new, useful and "non-obvious", which means that it can't be just in insubstantial improvement over what has been done before. I always recommend that you have a patent search run initially to see what other people have tried to patent in your field before you start spending money trying to protect it. Many patent applications are filed and many patents are granted on inventions that never end being commercially used, so just because you haven't seen it in use doesn't mean someone didn't think of it already.
Answered on Dec 30th, 2012 at 11:58 AM