Are my improvements to an already patented invention enough to spend the time, effort and money?

Without having knowledge of your inventive concept and the ability to analyze it with respect to the prior art, the below information is merely hypothetical and should not be construed as legal advice. Nearly every invention builds off elements that are in the prior art. Moreover, if you are willing to write your claims narrow enough, you can get a patent on just about any improvement, no matter how narrow. The problem is that claims that are incredibly narrow are virtually worthless because it would take very little effort for a competitor to design around your claims. You really need to read the published patent that you found (as well as any other prior art) with an eye for what you would claim. Think about what the critical differences are between your modificaitons and what is disclosed in the description of the prior art. You need to identify very specific claim language that is not found anywhere in the prior art. Once you identify the patentable differences, you have to ask yourself if a patent containing claims with those patentable distinctions could be easily avoided by leaving out some aspect of your claims. You are the only one that can decide if the differences could result in a marketable and profitable product. You may want to use the Public PAIR service on the USPTO's website to do a more detailed investication of the the prior art that you found. If this application has been examined, you could review any office actions to see what kind of difficulties you would likely face. Also, the may be other prior art identified by either the applicant or the examiner that could affect your decision. best of luck.

Without looking at the issued patent and comparing it to your improvements it is impossible to say much of anything about possible infringement issues. It may be possible to draft your application so that it doesn't require the other person's invention to be operable. In other words, your improvements might be able to stand on their own. If it isn't, it is still possible to obtain a patent on improvements to something that is already patented. In that case, you would not be able to make, use, sell, etc your invention if it infringed an underlying patent unless you worked out a deal with the other patent holder (probably a license or assignment). If the other product is not being marketed, the other inventor may be amenable to such an arrangement.

It is uncommon to find an inventor that has the technical legal training to analyze patents for their impact on the patentability of your invention. The analysis should be a joint effort between you and your patent attorney, where you are the expert regarding your invention and your patent attorney is the expert as to what is disclosed and claimed in the prior art. You should find a patent attorney that will be willing to help you through the analysis, weigh the costs and benefits and provide you guidance as to whether you will want to patent your invention (as well as whether your invention might infringe of the prior art!). Many patent attorneys (myself included) will help you through this analysis as part of a free initial consultation. You need to be informed before you can make a decision and your patent attorney should be there to help you. Good luck! -Patrick

You asked about the value of spending the time effort and money. The other answers do a good job covering the technical aspects, so I want to add to the value discussion. You need to think about why you want a patent. There are many reasons to get a patent, and in some cases even a very narrow patent has value. For example, Washington Mutual had a patet on the layout of their teller terminals, which if you ever went into one of their branches was quite different than most banks. You do not typically see banks filing patents, but when I heard their patent counsel speak at an event once she discussed how it had been a marketing strategy. They wanted to be able to describe their unique and patented customer experience in their advertising campaigns to differentiate themselves from competitors. Up to that time I had not seen that use of a patent, but by their estimation they had made millions off of what cost them tens of thousands of dollars to obtain. If you obtain a patent on improvements, you will have the right to exclude others from practicing the improvements, which can also take the form of being able to demand a licensing payment from anyone practicing the improvements. A patent will not, however, grant you the affirmitive right to practice the underlying elements that are already patented by someone else. You will have to obtain a license yourself from those patentholders. When determining whether you should get a patent yourself, you will need to consider what you are trying to guard against. Are you trying to prevent copycats of your improvements? Are you trying to give yourself business leverage with an existing patentholder by preventing them from entering an area so they will come to the negotiation table? Is the patent a vanity patent, such as in Washington Mutual's case where you just want to be able to say your invention is patented? Each of these considerations can change the value of the patent for your situation as well as affecting whether a narrow patent is acceptable or whether broad coverage is needed (which affects the cost).