Practical Skills for Corporate Patent Search

By An Ying,[Patent]

Patents can be either a source of market competition, or cause for litigation. However, many patentees rush into patent applications without fully understanding the state of technology. As a result, they find their own patent shield vulnerable all too often when confronting competitors as they still do not realize the importance of a patent search. The prior arts, in patent jargon, is a sea of information, which refers to all technologies, known to the public at home and abroad before the application date, including all of the published information, foreign or domestic, public use, or public information otherwise. Thus, even for an expert in a certain industry, the actual state of existing technology, without a patent search, may not be easily ascertained. Therefore, predetermination of the prior arts is key to whether or not, and how to apply for patents.

It is an extremely complex task to establish necessary prior art information, because much has to be factored in for the patent search, which requires the person conducting the search to be knowledgeable in patent, law, and in the relevant field of technology. Therefore, when preparing for patent litigation and related activities, the patentee may need a comprehensive and accurate patent search. In this case, it is better for the patentee to cooperate with qualified professional agencies. For daily R&D and patent prosecution, such research may be done in-house or by patent specialists. This article will give a few clues to the practical skills for corporate patent searches.

Typically, a corporate patent search, depending on purpose and function, can fall into the following categories:

New Product Development Search (Project Search): to understand the state of the art, and to collect relevant technical data in the R&D phase;

Novelty Search: to check for novelty and inventiveness for the potential patent application;

Clearance Search: to avoid infringing another’s patent, in the sales stage, when new processes or new products are marketed;

Invalidation Search: to find evidence and establish invalidity in the stage of infringement litigation or sales;

Export Search: to verify whether a particular technology has been patented in a target country at the stage of exporting the product.

Patent search refers to the process in which patent literature or non-patent literature related to certain technological subject matter is searched in the information database by certain search criteria. This article focuses on how to search patent literature.

The official database of State Intellectual Property Office (SIPO) is recommended: ( /) whose homepage includes the following:
The search criteria include: International Patent Classification (IPC) Number, Keyword, Applicant, Inventor, Application Number, etc. In most cases, only single data criterion may be sufficient for a simple search. For example, to find out the total number of patent applications filed by a particular corporation, the search can be done using the applicant’s name. For complicated searches, more than one criterion may be needed, e.g., for a technical subject matter search, a combined method of IPC number with keywords may be necessary.

We can also enter the patent search page by clicking the “Advanced Search” in the above search column. In this page, we can search for patent information by compiling retrieval relation and get the initial search results list. First, we can screen the initial results by the patent application number. Then we can filter the list by the information in invention names. Finally, we may click and enter the target file and receive a detailed screening according to the summary and other information, which can effectively improve the retrieval efficiency.

The Chinese patent application number carries the following meaning: before October 1, 2003, Chinese patent application number has 9 digits, “97101765.4”, e.g., in which the first two digits represent the year in which the application is filed; the third indicating the type of applications: 1 for invention, 2 utility model, and 3 design, 8 Chinese national phase of a PCT invention patent, and 9 for Chinese national phase of a PCT design patent. The fourth through eighth digits are the serial number in the class for that year. The last number after the decimal point is a mechanical parity bit. The patent application number after October 1, 2003 has 13 digits, “200710176242.6” for instance. The first four represent the year of application. The fifth means the type of patent application. The digits from 6 to 12 are the serial number for the application and the digit after the decimal point is also mechanical parity bit.

In addition, the search can also be done by the IPC number. On the right side of the above-mentioned page, there is a blank for IPC criteria. IPC criteria are usually combined with other search criteria. An IPC search may be done in two ways: one is by class headings listed on the left; the other is to first find a few somewhat pertinent references, and by following the IPC numbers on the references, ascertain the appropriate classification number.

The most challenging steps for a patent search are those of logical relationships between search criteria, which, e.g., are:

To preliminarily mark out a range of classification numbers by analyzing the elements/limitations of the subject matter;
To boil down keywords by the elements/limitations (which are normally the most generalized or generic technical terms for the subject matter to be searched);
To test search by the preliminary relations, and analyze the readouts;
To modify the preliminary relations after the analysis;
To remodify so as to establish a more reasonable relationship.

For the relationships, the keywords may be linked by different Boolean operators such as “OR” or the wildcard“+” to indicate that the existence of either or any of the keywords would meet the search criteria, while “AND” and “*” to indicate that the combination of both or all keywords must be present to satisfy the search criteria.

The correct choice of keywords can be done by lateral expansion and vertical restraints (also known as multi-feature combination). Take lateral expansion for example. The keyword “password” may be expanded to similar technical terms in this field. Multiple keyword searches can be used as: “password + key + ciphertext + keys + keyword + token”, or “password + key + ciphertext” can be expanded to “secret” and so on. Lateral expansion can prevent omission and increase the comprehensiveness of accessibility; while vertical restraints refers to the multi-feature combination, for example, “identification device based on biometric features” can be achieved by following multi-feature restrictions: “(biometric feature + bio-informatics + biological signal) * (certification + appraisal + identification + authentication + verification) .” Vertical restraints can prevent invalid search results and improve retrieval efficiency.

After the search, the readouts need to be compared and analyzed against the potential patent application. As a matter of principle, all references resulting from the search can be used for novelty purposes, to see whether all the elements of the potential patent application have been disclosed by a single prior art reference, and for inventiveness all references may be used either individually or in combination, to see whether the potential application is not obvious, which requires some knowledge of the patent law.

In addition, enterprises may also need to check the legal status of a patent, which can also be done through the SIPO’s portal as follows:

Other patent search tools are also available for retrieval, such as the Test System of Patent Information Service Platform:

Besides the patent literature published by SIPO, searches can also be done on patent literature publicly available in other countries by similar methods. For information, here are some commonly-used official patent search systems:

The European Patent Office:;

The United States Patent Office:, including PATFT for issued patents and AppFT for patent applications.

The patent family will be encountered in the retrieval, i.e. a single invention patented in several countries, which generates a group of the same or similar patent literature. In the same patent family, each patent literature is a member of the same patent family.

In fact, the function of patent search in enterprises is reflected in all aspects of economic activities. In defining R&D direction, a patent search for the industrial development will help to find greater space of development; when targeted at a certain technical problem, a search for existing solutions will help to raise the starting point for innovation; in the decision-making for particular market or country entrance, and a patent search in relevant geographical layouts will help to avoid obstacles. Enterprises’ own patent search includes the following three aspects: ①assessment over novelty and creativity of pending patent; ② product project search; and ③ tracking for rival’s technologies.

Novelty and inventiveness assessment will help enterprises predict the prospect of patentability and provide guidance for a patent agency in preparing the application documents, so that the agency may draft better claims, by effectively avoiding keywords and prompt secondary innovation.

Product project search is commonly used by means of querying to the market status of the project via network, magazines, conferences and other forms. Information will be collected on manufacturers, project types and current functions. Therefore, the applicant, technological keywords, IPC and other information will be analyzed so as to identify the applicant, reasonable combination of keywords, IPC and other information in the patent databases and then establish the project based on analysis results of patent retrieval.

Tracking of rival’s technologies should be treated as a day-to-day task. After identifying the competitors and competitive products, tracking shall be conducted on a regular basis according to the applicant information and the different levels of competitors (e.g., updating tracking records every 1, 3, 6, 12 months). Enterprises may analyze the trends in technology R&D, patent layout as well as techniques of competitive products. Moreover, reasonable keyword combinations can be selected based on competing products to find more new competitors.

Of course, this article has only introduced the methods commonly used by in-house technical staff or patent specialists in their daily work. As a complicated “systematical project”, the effects of a patent search are differentiated with regard to the experience, skills and knowledge of related personnel. Therefore, for high-demanding patent searches, it is suggested that enterprises cooperate with qualified and professional patent firms.

About the author:

An Ying, an attorney at Unitalen Attorneys at Law.

(Translated by Li Yu)

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