You need to develop and prove it WITHOUT divulging, or getting a patent.
The patent makes it public knowledge and it WILL be stolen by companies that have enough $$$$
to beat you in court...
I am sitting on at least 3 projects that could easily be brought to market, but I wont do it unless I can find a silent partner with enough
clout to discourage the vultures from taking the IP.
Also stay away from trade shows until you are bringing it to market. A good patent attorney should tell you these things and how to structure the release of the product...
If you know someone in industry who is well known, or has deep pockets, you should make a financial; arrangement with them to bring the product to market. I have had a few things stolen in the DOD aerospace realm because they know they can get away with it.
The financial partner doesn't necessarily need to invest, they just need to be a clear powerful threat to anyone who want's to take your IP.