• Google patents
    Search and read the full text of patents from around the world including more than seven million US patents.
  • Lens patent datasets
    Covers patents of European Patent Office, USPTO and WIPO as well as Australian patents.

Search for patents on specific subjects:

  • DPD (DNA Patent Database)
    A collection of DNA-based patents and patent applications issued by the United States Patent and Trademark Office (USPTO), with free access to full-text patents and applications.


A patent is an exclusive legal right granted by a government for a new invention. If patented, no-one else may commercialise the idea for up to 20 years. A patent is valid only in the territory under the jurisdiction of the granting government. Each country grants different kinds of patents and a different period of protection time. For example, in United States, there are three kinds of patents -- utility patents (20 years), design patents (14 years), and plant patents (20 years).

The importance of patents for engineering and science:

In order to be patentable, an invention must be "useful", "novel" and "unobvious" to "a person having ordinary skills in the art to which the said subject matter pertains". Patent documents help people to recognise technological trends at an early stage and give an idea of other research and development programs underway in their field. Patents are an essential source of information for engineering and science staff and students and engineers and scientists when they come to formulate their own R&D programmes and later convert them into technology, products and markets. Patents also provide a useful indicator for monitoring market trends.

Patent classification systems

Patent classification systems facilitate the searching and retrieving of patent documents by patent offices and other users. Most of the patent classifications have been designed so that each technical aspect of an invention to which a patent document relates can be classified as a whole. A patent document may contain several technical aspects of an invention, and therefore be allocated several classification symbols. Patent classification systems can be used in combination with other search terms, e.g., a keyword search, to restrict your search to the relevant subject area. For example, the word "WARN" can be combined with X22 (Automotive Electrics) in DWPI (Derwent World Patents Index) classification system to retrieve only those references on automotive warning devices. A patent classification ensures that all the patents of interest are retrieved when searching.

There are three major systems:

  • International Patent Classification (IPC) controlled by the World Intellectual Property Organisation (WIPO). The IPC is used world-wide - the industrial property offices of more than 90 States, four regional offices and the International Bureau of WIPO under the Patent Cooperation Treaty (PCT). There are eight sections (A - H) and these sections are further subdivided into classes. Each class consists of the section letter, followed by two digits. For example, H01 is the class designation for Basic Electronic Elements and F17 is the class for Storing or Distributing Gases or Liquids.
  • US Patent Classification System is used to classify patents granted by the USPTO. Provides for the storage and retrieval of every US patent document that a patent examiner needs to review when examining patent applications. It is the best system to search for US patents.
  • Derwent World Patents Index (DWPI) Classification

WIPO Country Codes

The World Intellectual Property Organisation Country Codes is available on the Derwent World Patents Index (DWPI) website with an alphabetical list by either Country Name or Country Code.

Patent search tips

Generally, there are five ways to search a patent database:

  • Search with a patent classification:
    • IPC (International Patent Classifications) in almost all the patent databases
    • DWPI classification for Derwent World Patents Index databases
    • USPTO classification for US patent databases
  • Use free text searching or full-text searching where you can search for a keyword everywhere in the text.
  • Search for a patent number, e.g., US4148102, EP54596, WO9802986, JP6005310.
  • Search for patent assignees - the person(s) or corporate body to whom all or limited rights under a patent are legally transferred, such as Smith, John or NASA.
  • Search by keyword.

Obtaining patents

Copies of a patents are available from:

Web resources

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Last updated : 16 April 2021
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