What are patent citations, and how many different kinds are there?

Patent citations are a powerful tool for retrieving information, from finding additional prior art, analysing licensing and commercialisation opportunities to infringement analysis and the gathering of general information about competitors.

However, they should be used with some foreknowledge since not all of them say the same thing about the topic at hand. Therefore, it is essential to understand the different kinds when applying patent citations to different business uses. Broadly, patent citations can be categorised by the direction of the citation and who generated them.

If we start with a single patent (the source patent), and look at references associated with it, we can discuss the directional nature of citations. Backward citations are previously published patents and non-patent literature mentioned by the source patent. By contrast, forward citations are documents published after the source patents that reference it.

The second broad category associated with patent citations is based on who is generating the citation—although a detailed explanation of all the sources is beyond the scope of this article. Still, they can be reduced to whether the citation comes from a patent office examiner or another entity, such as the organisation applying for a new patent or an interested third party in an invention.

Examiners refer to previous inventions to determine whether a new invention should be awarded a new patent. They classify these in three ways: whether a cited reference challenges the novelty of the new invention by themselves; whether the reference needs to be combined with another reference and challenges the obviousness of the new invention; and whether the reference discusses the same ideas as the new invention, but may have been published after the new invention was already filed with the patent office.

Identifying patentable inventions

Applying for a patent is not free. Simply filing in one country can cost between $10, 000 and $20,000, so it’s essential that organisations applying for them have a clear understanding as to whether their application is likely to be granted. Many companies will conduct a patentability search before filing, to lower their risk of getting a patent rejected after they’ve already invested a large percentage of the total costs of prosecution.

There are many approaches to conducting a patentability search, but one of the most efficient is to look at the backward citations of at least one related document. Even if the corresponding reference doesn’t challenge patentability itself, there is a good chance that citations for that document will provide a clearer picture of whether the new application will be granted.

Ensuring a return on investment

When starting research, it is difficult to predict whether that technology investment will result in a commercial product allowing the company to get a return on time and money spent. In some cases, the best way to ensure a return on investment is finding other companies that are interested in acquiring or buying the technology.

Forward citations are an excellent way of finding potential buyers who aren’t direct competitors. A possible list of licensees or buyers can be found by looking at non-competitors who have expressed an interest in an invention.

Benchmarking your technology

Forward citations, especially those coming from examiners or third parties, are indicators of how influential an invention is within its field. When this type of analysis is used to compare two companies, it is possible to rate the inventive prowess of the different organisations.

This is one of the best methods for measuring the effectiveness of the research and development (R&D) output of a company. When looking at two companies with similar R&D budgets, the one that is cited more frequently is arguably delivering the more significant impact in the technology space.

Patent citations are really useful, but where can I find them?

Several outlets provide access to patent citations, but most of them tie citations directly to each individual document. This can cause issues when most analyses are done at the patent family level.

For example, a PCT document in the family can have citations to it and the US pre-grant application if the US granted patents and similar documents in Europe. These documents cover the same invention and can have essentially the same claims, so which document should be used to record the number of forward citations? The answer is all of them, since they are citations to the invention or claimed subject matters.

One of the few databases that allows all citations to all documents in a patent family to be aggregated together is PatBase from Minesoft. This platform provides the patent family as a unit of record instead of individual documents, which makes it easy to find all the citations for the whole family, whether forward or backward.

PatBase has one of the largest collections of citations from many global patenting authorities that publish patent citation data. This global coverage, along with the patent family data, makes PatBase an ideal choice for analysts who want to take advantage of this important patent data source.

A lot of nuances are associated with the use of patent citations. They go by many different names and types, and can be used for a significant number of objective measures. It can take a little time to get comfortable using them, but the savvy analyst will find that they can provide insights that aren’t available from other patent data.

To find out more about PatBase, visit www.minesoft.com

Anthony Trippe is managing director of Patinformatics. He can be contacted at: tony@patinformatics.com

Tim Campbell is vice president at Minesoft. He can be contacted at: info@minesoft.com

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