Google Patents is the one of the best resources for doing patent searches and is still the one that I use for prior art searching. In addition to having features that allow for keyword searching, the real gem is the indexing of patents and patent applications that were cited in examination of that application and later applications that cited that reference. These features effectively allow you to leverage the patent searches of patent examiners instead of having to do all the hard work yourself.
As discussed in detail in Patents Demystified, patent searches are easiest and more likely warranted for mechanical inventions. On the other hand, software related prior art searches are difficult and often less relevant in early stages. Accordingly, the following discusses how to do a patent search for non-software related inventions using Google Patents. Also if you want to expand your prior art search, don’t forget about other resources like the USPTO patent and patent application searches, Google Scholar, and the like.
1) Mindset When Embarking on A Prior Art Search
Begin by assuming that you will find many patent references that are similar to your invention and a few that are very similar. If you haven’t found references like this yet, then you need to keep on searching until you do. In fact, I am yet to do a patent search or get one back from a patent Examiner where at least some close references are found. If you do a good job on your search, you will likely find some prior art that concerns you.
However, as discussed in detail in Patents Demystified, close prior art does not necessarily mean that your invention will not be patentable. Regardless of whether you find things that seem too close to your invention or whether you feel like none of the prior art you found is on point, let your patent attorney help with the analysis of whether your invention will be patentable or not.
Also, think of your search like mining. For example, many types mineral or metal deposits occur in veins or are otherwise concentrated together in a small area. Outside that area, there may be little trace of the valuable material and mining may seem futile and arduous until a concentrated pocket is found. At that point, focusing on such an area can often quickly and effortlessly yield results and can even lead to even richer deposits. Similarly, the beginning stages of a patent search often feel like nothing relevant is being uncovered and then suddenly a large group of relevant references are found all within a short time. In other words, don’t be surprised if you feel like you are spinning your wheels for the first hour or more, especially if you are new to prior art searching.
2) Start With A Text Search
Kick off your Google Patents search with a targeted text search that captures the essence of what the invention is and what makes it novel. For example, a good starting search query would be “[item] with [novel feature].” For example, if you invented an umbrella with a knife hidden in the shaft, a good starting search could be “umbrella with sword.” Since it can be easier to look at the pictures of U.S. patents and published patent applications on Google Patents, consider limiting your search to only the US patent office even though publications from other patent offices can be a source of prior art.
3) Find the Most Relevant Results of the Search
Look at the first 10-30 results of the text search one-by-one and write down the patent or publication number of any reference that you feel is similar to your invention. Flip through each of the drawings first and maybe look at the text if necessary. At this early stage, you want to try to make a quick evaluation taking only seconds or minutes per result.
Note the ones that are most relevant, if any. If nothing seems close to your invention, consider starting over with a new text search and repeating this step. Experiment with more specific search queries or broader ones and think about alternative terms to describe the invention in general or the point(s) of novelty. For example, using the umbrella knife as an example, you might try different combinations of umbrella or parasol with knife, dagger, blade, sword or the like. When you find some results that you think are relevant. Move on to the next step.
4) Look at the “Patent Citations” and “Cited By” References
At the bottom of the Google Patents page for each patent or patent publication there is a section for “Patent Citations” that lists all of the prior art references that were cited by the Examiner or applicant during the examination of the patent application. Also, there is a section called “Cited By,” which lists all of the later patent applications that cited this reference during examination.
Look at all of the patents and patent publications in each of these lists, and assuming the base patent or patent application was relevant enough, you are very likely to find some relevant prior art within these lists. Write down the number of all of the most relevant prior art references that you find.
5) Then Just Repeat!
For each of the most-relevant prior art references that you find in the “patent citations” and “cited by” lists, also look at the patent publications in their “patent citations” and “cited by” lists, and so forth. Two things will happen as you do this over time. First, your perspective of what is relevant will become more focused and what you considered relevant in the beginning of the search will seem completely irrelevant compared to the things you find relevant later on. In other words, as you continue your search, you should be honing down on more and more relevant results over time.
Also, at some point, you will start seeing the same references pop up in other relevant cases and that is what will ultimately prevent you from iteratively searching forever.
6) Read the Most Relevant References You Find
Once you feel like you’ve done an exhaustive search using the iterative method above and found some close results (usually within 1-3 hours), take a look at the most relevant references in detail if you have not already done so. 3-10 patents and/or patent application publications is usually a reasonable number. Focusing on the drawings during the main search helps speed up the process, but at some point, you want to read the text of the patent itself and see what it has to say. Sometimes it has additional details that are not shown in the drawings and these might be relevant to your invention.
As discussed in Patents Demystified, don’t make decisions about the patentability or un-patentability of your invention without the help of a patent attorney. For example, it’s hard to know how close is “too close” when it comes to prior art. In some cases, seemingly disastrous prior art can be easy to get around, whereas in other cases, seemingly irrelevant prior art can be the basis for an unbeatable obviousness rejection.