Patent Law. Adding my name as inventor to already existing patent

As mentioned above, there are ways to add an inventor to an application as well as add an inventor to an existing application. However, and this is very important, you would need to be an inventor under the law.

Since you were not listed on the original patent application as an inventor, to simply add you now would be improper.

If the original patent application is still pending, it may be possible to add you as inventor in conjunction with the filing of a "continuation-in-part" patent application, wherein your new material is added to the disclosure of the original patent application.

All of this can be a bit tricky and you should seek competent professional advice ASAP because timing can be critical.

This answer is not intended to be legal advice or to create an attorney-client relationship. All information posted is for educational purposes only and may not be applicable to any specific person or situation.

In addition to the answers provided above, it is important to understand that you cannot add new matter to a pending patent application nor to an existing patent. The new matter you propose that solves a technical problem for the invention needs to be claimed in a new application, since the patent in question has already issued. This new application may be an improvement over the invention claimed in the issued patent, and if you conceived of the inventive material claimed in the new application along with the original inventor, then you are a joint inventor in the new application.

I urge you to engage your own patent attorney for further consultation. Most patent attorneys will provide an initial consultation at no charge.

Your solution to technical problems with an existing patent appear to be an improvement patent. An improvement patent does not need to involve the original inventor to be a stand alone patent. You could file a patent that has the claims of the original patent with the additional improvements you have conceived. But, you could not practice your improved invention without a license from the owner of the original patent. Likewise, the owner of the original patent could not practice your improved invention without a license from you. This is what happened with the lightbulb and using tungsten instead of cotton for the filament. Tungsten was significantly better than cotton, so each inventor had to accept a cut of the profits. So... you and the original inventor need to work out some agreement which both parties feel is fair, put it in writing, and protect it with the proper patents, etc. I strongly urge both of you to separately obtain legal counsel to mediate and negotiate a fair agreement. Also, not to burst anyone's bubbles, keep in mind, 95% of all patents never become successfully commercialized.

Peace be with you, and may love guide you.

I agree with the previous answers. It is indeed a complex issue. It sounds like the "technical issue" may flag a serious deficiency with the issued patent. If an artisan of ordinary skill in the art cannot practice the invention without your "solution" then the invention is technically flawed and as a result is in-operational. Consequently, the disclosure is not enabled. This would serve as an incentive to stimulate the inventor to cooperate with you. A detailed analysis will determine your options. Consult a Patent Attorney. Good luck!