Searching for Japanese Patent Numbers on Derwent World Patent Index (Derwent WPI)

Search Tips - August 2000

Searching for Japanese patents can cause problems due to the patent number format being unusual in some cases, so here’s our guide to successful searching of these numbers on Derwent WPI.

Derwent includes three types of Japanese patent documents in the Derwent WPI database. These are:

• Unexamined application (Kokai) - Kind Code A
• Examined specification up to 29.05.1996 (Kokoku) - Kind Codes B and B2
• Granted patent after 29.05.1996 (Toroku) - Kind Code B2

Each of these has their own numbering system, so we’ll look through each one to see how they are handled on Derwent WPI.

Unexamined Applications (Kokai) - Kind Code A

Before January 2000, these application documents were numbered using a system that included the Japanese Imperial Year (which is based on the rule of the Japanese Emperor), and this Imperial Year is also present in the number used on Derwent WPI for these documents. The general format for these document numbers on Derwent WPI is:

JPYYNNNNNN

YY = Imperial Year; NNNNNN = serial number, made up to 6 digits if necessary using leading zeros

Example: Kokai number 11-12345 appears on the Derwent WPI database as JP 11012345, i.e. the Imperial Year followed by the serial number, made up to 6 digits by adding a leading zero. This can be searched as:

From January 2000 onwards, the imperial year is no longer used on the original documents from the Japanese Patent Office, and the Western year is now used instead. The general format for these document numbers on Derwent WPI is:

JPYYYYNNNNNN

YYYY = Western Year; NNNNNN = serial number, made up to 6 digits if necessary using leading zeros

Example: Kokai number 2000-123456 is stored on Derwent WPI as JP 2000123456, and can be searched as:

Examined specification up to 29.05.1996 (Kokoku) - Kind Codes B and B2

These patents are more difficult to find, because the Imperial Year in the original patent number is converted into the Western Year on the Derwent WPI database. So, to search for these documents on Derwent WPI, you need to know which Western Year corresponds to the Japanese Imperial Year of the document you want to search for. Use the following table to help you:

* patents issued from 01.01.89 to 09.01.89 have Imperial Year 64

The general format for these document numbers on Derwent WPI is:

JPYYNNNNNN

YY = Western Year; NNNNNN = serial number, made up to 6 digits if necessary using leading zeros.

Example: Kokoku number 57-126 is represented on Derwent WPI as JP 82000126, the Imperial Year 57 is converted to Western Year 1982, and the serial number 126 is made up to 6 digits using leading zeros as before

Granted patent after 29.05.1996 (Toroku) - Kind Code B2

These granted patents are easier to search for, as there is no year element in the numbering system. The documents are numbered sequentially, starting from 2500001.

The general format for these document numbers on Derwent WPI is:

JPNNNNNNN

NNNNNNN = 7-digit serial number, as it appears on the original document

Example: Toroku number 2901237, published in 1999, appears on Derwent WPI as JP 2901237, and so can be searched as:

Searching Application Numbers

Finally, the application or filing number for each publication is also searchable on Derwent WPI. Once again, the Japanese Imperial Year of the original is converted to the Western Year for Derwent WPI.

The general format for these application numbers on Derwent WPI is:

YYYYJP-NNNNNNN

YYYY = Western Year; NNNNNNN = serial number, made up to 7 digits if necessary using leading zeros.

Example: Application number 9-187486 appears on Derwent WPI as 1997JP-0187486 , with the corresponding Western Year and also with a leading zero to make the number up to 7 digits. So this application number can be searched as:

Further details of Derwent’s coverage of Japanese patents, including details of the Japanese numbering of PCT documents, can be found in ‘Global Patent Sources’, available from Derwent.

For further assistance please contact your local Derwent Help Desk.