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Patent Families

Why is a patent family necessary?

Since patents must be applied for at a national level rather than at an international level, it means that a single invention is often associated with numerous identical patents around the world.

For this reason, the idea of a patent family was introduced so that patent analysts can rapidly identify patents that relate to a single invention around the world.

A patent family is a collection of patent applications covering the same or similar technical content.

In other words, it is “the same invention disclosed by a common inventor(s) and patented in more than one country.”  Patent families can be regarded as a “fortuitous by-product of the concept of priorities for patent applications”.

According to the Paris Convention, inventors have one year after filing their initial patent in one country to file for the same invention in other countries. They must claim “priority” from that original patent in order to ensure that no invention filed by anyone else in that year can be taken as prior art when assessing patentability. It is also possible that a patent may claim priority to more than document because this patent may be describing multiple similar ideas which can't be all referenced from one previous document.

Also working their way into the definition of a family are different “versions” of documents, such as revisions and amendments to an application, or reissues of granted documents.

Finally, it’s worth noting that there is no such thing as an official definition of a patent family:

"Patent families are defined by databases, not by national or international laws, and family members for a particular invention can vary from database to database." – Edlyn Simmons

That said, let’s look at what definitions PatSnap has used for the different types of families…


Extended Patent Family

An extended patent family is a collection of patent documents that cover a technology. The technical content covered by the applications in one extended patent family is similar but not necessarily the same.

Patent applications that are members of an extended patent family will all have at least one priority in common with at least one of the other members – either directly or indirectly.

In PatSnap, you'll find two types of Extended Family:

INPADOC Extended Family

We keep the INPADOC extended patent family the same as OPS (EPO Open Patent Services).

In PatSnap the DOCDB simple patent family is displayed “INPADOC” under the tab “Patent Family”,  not all the priorities that are listed in PatSnap patent family data are taken into account.

When using PatSnap, we would recommend using the PatSnap Extended Family, as it will cover more jurisdictions, and uses many cleansing techniques including normalization and data correction to ensure that as many documents are returned as possible.

PatSnap Extended Family

All patent documents are linked (directly or indirectly) via a priority document belonging to one patent family.

The extended families allow for additional connectors to link other than strictly priority date. These include: domestic application numbers, countries that have not ratified the Paris Convention, or if the application was filed too late to claim priority. You can find out more about our Extended Family here: What Is PatSnap's Extended Family? 

Simple Patent Family

A simple patent family is a collection of patent documents that are considered to cover a single invention. The technical content covered by the applications in one simple patent family is identical.

In other words, if you’re looking for a group of patents that cover the same invention, look at simple families.

Patent applications that are members of one simple patent family will all have the same priorities.

Continuations and divisionals are considered to cover the same technical content as the parent application. Continuations and divisionals will always be in a patent family with the parent application, regardless of the priorities that they claim.

PatSnap uses the DOCDB definition of Simple Families and consolidates this data directly from the EPO.

If all the priorities of two documents are the same, they are referred to as "equivalents". This is the definition used in PatSnap under “Also published as”.

Note – this rule is good for most situations, but an exception can be when an additional WIPO application is claimed as priority.


How are these families related? 

Simple Family


So, the smallest possible version of a family will be a simple family. Remember, this is typically made of records that claim the same priorities.



If we link this group of patents with any other patents that claim priority from any of the same documents, we end up with an INPADOC Extended Family.

Extended Family

PatSnap may also find additional (or occasionally less) members of a patent family during our data normalization and linking process, outside of what the INPADOC has defined. We call this PatSnap Extended Families. These additional members will be related to any or all of the simple families.


What Are The Different Types Of Patent Family Members?

Why do some patents in a family claim different priorities? Well, that's down to their contents.

  • Are they talking about the same invention and protecting the same things?
  • Are they protecting the same invention but claiming (and therefore protecting) the same aspects using different wording?
  • Are they altering their original invention completely?
  • Can the invention actually be seen as two or more distinct inventions?

Given below is an explanation of each of these things. After each area, a very basic example is given to illustrate what that members might look like compared to the original invention.

Remember, these terms are largely localized to the USPTO. Other jurisdictions may have similar concepts but those will not be defined here.



When someone files a patent, naturally the desired outcome is to obtain as strong a protection for an invention as possible. One of the ways to increase the protection on an idea (another way to say this is to "increase the scope" of protection) is to file a continuation. This is a patent application that continues the examination of the application. Whilst more expensive, it is a route many applicants take in order to protect their ideas.

Whilst the original patent issues, one can argue for a different definition on what is being protected. Most often this will take the form of different or reworded claims on the second invention. It's a way to take one application and turn it into another or two more documents.

There are many clear reasons to file a continuation:

  • Whilst your first patent should always be as "strong" as possible, it might be wise to approach the invention from several descriptive angles to reduce the likelihood that another applicant can describe the same invention in a way that navigates around and therefore doesn't infringe.
  • If you have multiple sets of claims, then it's harder for competition to understand exactly what the limit of your invention is. If you keep filing continuation after continuation, the definition of what you have invented is largely ambiguous and will prevent competitors from being able to define their own patents. It's a bit like when you're having an argument; it's tough for someone to rebut what you've said until you stop talking!
  • Bigger patent families tend to be more valuable. If your R&D team has created one invention, then would you rather have one patent around that, or six? Increasing patent output is a performance indicator for many organizations and the more valuable IP you can extract from a single invention, the better.


Original Invention: Chair with four legs, a seat, two armrests and a backrest.

Continuation: Chair with four vertical supports, seat, horizontal cushion and a spine support mechanism.



It's not always enough to talk about the same invention in different ways. Occasionally (or often, depending on the applicant), you'll see variations on an invention. And a lot of the time, the variation is close enough in scope to an existing invention, that you can file a continuation-in-part. For example, if your original invention constitutes a chair, with four legs, two armrests, and a seat. That is everything described in the description area of the document. A continuation-in-part would add subject matter to that description - in this example that might be a cup-holder built into the armrest of the chair.


Original Invention: Chair with four legs, a seat, two armrests and a backrest.

Continuation-in-part: Chair with four legs, a seat, two armrests, a backrest and cup-holder.



In some circumstances, it may turn out that an invention that's been filed actually constitutes two separate and distinct inventions. Let's say in our example, our chair had an added technology of a speaker embedded into the headrest. The patent examiner may look at this invention and see it really as two distinct inventions - a chair and a speaker. At this point, the patent examiner would recommend to the applicant that they file two separate documents (both of which would claim priority from the original) that each describe a single and distinct invention.


Original Invention: Chair with four legs, a seat, two armrests, backrest, amplifier, sub-woofer and 2 main speakers.

Divisional 1: Chair with four legs, a seat, two armrests and a backrest.

Divisional 2: Amplifier, sub-woofer and two main speakers.






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