This really depends on whether or not the company has a policy as to inventions. Many companies do and it notes that if something was invented during the course of you work, you agree that the invention belongs to the company. You need to look into that. More importantly is determining how long the company has been using the invention. If it has been more than a year, then this is irrelevant as patent protection is not available any more.
The answer to this question is for informational purposes only and does not form an attorney-client relationship.
1. Who can file:
As you are the inventor of the device, you would be able to file for the patent application. Your company may also be able to file an application if you are under an obligation or have assigned the application to the company. In addition, the company could also file on your behalf upon certain proof.
2. Who owns the patent:
As attorney Malek noted, that depends heavily on your employment agreement. It would also depend on if you invented the design within your scope of employment. If you created it out of your scope of employment, your company may still have some rights in using your patent.
3. Would you be able to get a patent:
As attorney Malek notes it would depend on many factors, including how long the company has been using it and if there has been any public disclosure. You would need a patent attorney/agent to look over your case to see if you have anything that would prevent you from getting it.
Patents are very complex and I would highly recommend talking/meeting with a patent attorney/agent to discuss the details of your situation and help you in determining if you want to pursue a patent.
Answering of your question is merely general advice and does not constitute legal advice. None of the statements or implications made by this answer creates an attorney-client relationship with the attorney answering the question. The statements made in this answer are not to be solely relied upon and you should meet with a competent attorney to discuss any concerns you may have regarding this answer.
You may be obligated to assign it to your employer. If so, there is no point in wasting money on it. If your employer waives its rights, then you may seek patent protection, provided there are no statutory bars. Seek legal counsel before taking any action.
This is not a legal advice or solicitation, and does not create an attorney-client relationship. Consult with an attorney. I work for Cardinal Risk Mangement and Cardinal Intellectual Property, IP service companies, but not law firms. I also am the president of Vepachedu Educational Foundation Inc., which is a non profit educational foundation. I also write cultural and scientific compliations for the foundation. I also teach at Northwestern university as a guest lecturer. I also provide some pro-bono guidance on immigration and other issues through Indian American Bar Association. I also have a contract with Cardinal Law Group, a law firm, for IP projects. All this information is on my profile at Avvo and also at Linkedin. Any views/opinions expressed in any context are my personal views in individual capacity only, and do not represent the views and opinions of any firm, client, or anyone else, and is not sponsored or endorsed by them in any way.
My colleagues are correct in their suggestion that you look to your employment agreement to resolve the question as to whether you have the right to own the patent on your invention. But that is NOT the end of the analysis. Most states have a statute or two that set the conditions that define when an employee, or the employer, owns the patent rights to inventions created by employees in the scope of their employment. You need to speak with a Washington-licensed intellectual property attorney.
The above is general information ONLY and is not legal advice, does not form an attorney-client relationship, and should NOT be relied upon to take or refrain from taking any action. I am not your attorney. You should seek the advice of competent counsel before taking any action related to your inquiry.
I concur with the other posters: the terms of your employment will likely cause your employer to own the invention and any resulting patent. However, that doesn't mean there isn't some value in pursuing a patent application and being named as an inventor on it - being named as an inventor on a patent comes with some prestige and could enhance your career prospects. I recommend consulting with a patent attorney to explore your options.