Patent Family Searching using Derwent World Patents Index (Derwent WPI)

Search Tips - April 2000

What is a patent family?
Patent protection is country specific. That means that if a company or an individual wants to protect their invention in a particular country, they must apply for patent protection in that country - either by filing a national patent application, or by making their application via one of the multi-national routes (e.g. an EP or a PCT application). If protection is sought in more than one country, or through more than one patenting authority, this will result in what is known as a family of patents. With certain exceptions (as described below) and within the constraints of its country coverage, Derwent gathers all of the patent documents relating to an invention into a single database record. In general, one database record in Derwent WPI represents one invention and shows you all the patent documents which Derwent has collected relating to that invention.

How does Derwent decide whether a patent belongs to a family?
Derwent uses priority data to decide whether or not a patent document can be added to an existing family (i.e. to decide whether or not it is an equivalent). But what is "priority" in the context of patenting? Under the terms of the Paris Convention, a patent applicant is given twelve months after filing his first application in which to file further applications in other member countries. Provided they are submitted within this time limit, all these subsequent applications are then treated as if they were filed on the same day as the first application (and this has all sorts of important implications for the subsequent protection obtained). The first application is know as the priority and the details associated with it - date, country, etc. - are known as the priority data. These details will appear on the front page of every patent document and, along with other factors such as the patent assignee and subject matter, they allow Derwent to match equivalents into existing families - or, if appropriate, to make the decision to create a new database record. Incidentally, Derwent also checks for non-Convention equivalents - patents which have been filed outside the twelve month deadline but which belong to the same applicant and cover the same subject matter. Checking for these is an essentially manual process and bringing them into the appropriate families - so that you can see them alongside all the other relevant patent documents in the record - is a unique service which Derwent provides.

Why are patent families important?
By looking at the patent family, you can see the global picture of where the company or individual has chosen to seek protection for their invention. This is important from a legal point-of-view and can also tell you a great deal about the owner's plans for the eventual marketing of the product. The size of the family is sometimes an indication of the significance of the invention (and the amount of money its owners are investing in it) and it is always interesting to see which particular countries have been chosen - and whether there is any trend in the way these have changed (indicating a shift in marketing strategy perhaps). If these ideas are of interest to you, then you might like to attend one of our Patents for Competitor Intelligence classes where we discuss the topic in much more depth. In the context of a Derwent WPI search, the key thing to know is that Derwent gathers the patent family together for you - usually into just one database record. So when you display your search results, everything is there for you to see without the need for extensive further research.

That sounds easy. Surely there's more to it than that?
It is usually very straightforward. In most cases, the complete patent family for the invention will be gathered into a single Derwent WPI record. However, there are occasions when the patent family will be spread across two or more records. This will occur when there are multiple priorities - resulting from some kind of change taking place while the patent application is working its way through the system. Examples of this are continuations, continuations-in-part and divisionals - all of which are explained in our glossary. Derwent applies strict rules when bringing the members of a patent family together and these rules have in fact been made even stricter within the last few years. Prior to Derwent Week 199216 (i.e. mid-1992), a patent was considered to be an equivalent if it claimed the same latest priority as another patent already recorded in the Derwent system. Since 199216, all priorities must exactly match in order for the patent to be incorporated into the family. If this criterion is not met, the patent in question will be placed in a separate database record. This of course means that it is sometimes necessary to add an extra step to your search in order to gather together all the members of a "scattered" patent family.

OK. So how do I deal with these complicated situations in my Derwent WPI search?
One thing you can do is look out for any records with more than one set of data in the priority field. As per the example below :

Priority Applications (No Type Date): US 9329755 A 19930311; US 91763026 A 19910920

Whenever a record contains multiple priorities this should alert you to the fact that this particular record may not contain the whole patent family and there may be more members of the family to be found elsewhere.

With a single record, or just a few records, this is easy. But you do not need to do it for a whole set of records. The hosts - Dialog, Questel.Orbit and STN - provide automated methods for identifying and bringing together the members of a scattered patent family. Some of these methods can be applied to sets of records (or single records) retrieved in a search; others of them can be applied very simply to patent numbers or application numbers - without the need for a previous search. Let's look at what each host offers.

Family Searching on Dialog
We know that the members of a "scattered" patent family will have at least one priority in common, so all we need to do in order to gather the family members together is look for records with matching priority data. The first step is to retrieve the record containing the patent that you already know about:

? S PN=GB 2276007

S1 1 PN=GB 2276007

Next, we apply Dialog's MAP command. This is a command which can be used in many different contexts, but here we are going to use it to extract all the priority data (ANPRYY) from this record (or from this set of records), save it and re-search it. The letter "T" within the command means that it will not be saved permanently; it will disappear as soon as we log off and we will therefore not incur any longterm storage charges.

? MAP ANPRYY T 1

Select Statement(s), 2 Search Term(s)
Serial#TD256

Now we can execute the saved search by typing the command "EXS". (The search has been given a serial number by Dialog - TD256 - but we do not need to take any note of this since we are going to execute the search right away.) Dialog will now search the whole of Derwent WPI for records containing the priority data we extracted from our original record.

? EXS 1

AN=US 29755-1993 2
AN=US 763026-1991 2
AN=US 29755-1993 + AN=US 763026-1991

S2 2 Serial: TD256

There are two database records sharing this priority data. Now we need to repeat the process, extracting the priority data from these records and searching for further matches.

? MAP ANPRYY T

1 Select Statement(s), 2 Search Term(s)
Serial#TD257

? EXS 1

AN=US 29755-1993 2
AN=US 763026-1991 2
AN=US 29755-1993 + AN=US 763026-1991

S3 2 Serial: TD257

The key thing to notice here is that our result is the same as before; we have not gained anything by repeating the mapping process. As soon as this "stable" stage is reached, you know that you have retrieved all that there is to retrieve in connection with this particular family and you can stop. (Here it took two iterations; it may of course take more in particularly complex cases).

Family Searching on Questel.Orbit
For users of Questel.Orbit, the process is very simple. All you have to do is apply the special FAM command - to a patent number, an application number or a priority number. For example:

Or

Or

Family Searching on STN
For users of STN the process is very simple. All you have to do is apply the FSEARCH command - to a patent number, an application number or a priority number - to bring together a whole family. In response to this command STN will run an automatic iteration (which will be shown on your screen ) hunting for all the appropriate data. One or more iterations will be performed, as necessary. All you need to do is enter the FSEARCH command at the very start - the rest will be done automatically by STN. For example:

Or

Or

You can also use FSEARCH to sort an L-numbered set of records (ie the results of an earlier search) into families. In addition to sorting the records already present in your set, STN will also find all the other relevant records in the database. This means that, after applying the FSEARCH command, your L-numbered set may be larger than it was before.

Can I use these commands to search for records appearing in other databases?
Yes, you can use the patent family commands detailed above in multi-file environments e.g. with INPADOC or CAS, to access any other files that contain patent information which are available via the host that you are using.

For further assistance please contact your local Derwent Help Desk.