For a successful patent, your design must have/be:
- state of the art. This means no public disclosure AT ALL except for the purposes of testing with companies under confidentiality agreements.
- novel. This means beyond what is already available on the relevant markets. This must not be an obvious step forward in the area, as judged by the reasonable man skilled in the art. This reasonable man also speaks all languages.
- the item must not be reverse engineer-able. That is, someone who comes along mustn't be able to deduce how it works by working backwards from the finished product. If they could, your patent would be pointless as someone could simply engineer it a different way.
-there is an argument for a social utility function.
I remember a case whereby a designer of a infra red based cat flap was denied a patent because of a drawing in The Beano that showed a cat wearing a transmitter.
I am presuming you are based in England or Wales.
There is no guarantee that the patent will make you money. There is/was a patent for a cat flap in a nuclear bomb (I'm not joking). The man seemed a bit nutty; he claimed his cat Ginger spoke to him. And no, I don't know why all my random patent stories involve cat flaps :-)
A patent gives you a 25 year monopoly right over the production/licensing right for the patented item for 25 years- unless it's a drug that requires governmental approval, in which case an extra 5 years grace may be applied for.
Hope this helps; any other questions, just ask!