Consider (Score 2)

I'll first echo the others here who have stated that you should get your own lawyer who can review your employment agreement and discuss the situation with you.

Second, you should know that there are proceedures for prosecuting a patent application over the objections of an inventor. The inventor (you) will still be listed on the patent and the patent will still issue in your name even if you've actively refused to sign the oath/declaration . If you also refuse to sign the assignment, your former company may end up suing you for breach of your previous employment contract (note that just because you've left the company your obligations under your employment agreement haven't necessarily ended). Also, your refusal will not appear on the printed patent that most people see -- it would only appear in the file history which is only generally seen during litigation/licensing negotiations/enforcement.

Third, you may want to take some time and talk to the attorney drafting the application for your company. He/She (he from here-on-out because I'm lazy) should be able to explain to you the differences between what is described in the patent application (typically called the detailed description) and what is claimed in the patent application. For example, most patent applications describe various elements necessary to understand the invention, even though those elements aren't actually going to be claimed. What is claimed defines the scope of coverage of the patent.

Fourth, you've have no duty to search for/find prior art not within your knowledge. However, if you feel that the attorney has drafted the claims too broadly (i.e. the claims attempt to protect things that others have already invented), you need to communicate that to the attorney drafting the application so that the application can be drafted more correctly. Your company's policy on searching for/finding prior art may vary. However, providing relevant prior art with the application results in better prosecution on the patent office side and a stronger patent in the long run.

Good luck!

DISCLAIMER: See professional legal advice from competent legal counsel. I don't know all the facts and am only providing you some general information about patents -- do NOT rely on this information -- speak with a lawyer! I don't represent you. Any opinions herein are mine and not those of my employer or anyone else.