A patent search is a process of identifying existing patents related to an invention or idea. A patent search is not legally required, but it can be a crucial part of figuring out whether any prior patent will interfere with your ability to acquire a patent or there is duplication of research efforts. Filing for a patent and acquiring a patent can be expensive. Before applying for a patent, even before you start a R & D process, you should conduct a patent search.
Patents may cover broader concepts and they don't specify the final packaging, detailing, manufacturing processes, trademarked names, and other aspects of products.
Searching patents by names of products, whether Formica or Blackberry mobile devices, rarely provides a direct path to the invention in question. Final product names are often determined long after patents are filed (trademarks rather than patents protect product names). In addition, the final product may be an amalgamation of several patents. So searching patents for, say, Apple's popular iPad requires knowing that the relevant patent was titled “Proximity detector in hand-held device" and never once uses the term iPad.
Patents are legal documents and usually written by attorneys for analysis by patent examiners. They lack the directness of specifications, technical standards, or other types of descriptive documents. They often employ a specific legalistic vocabulary.
While patent applications are subject to examination by patent examiners, they are not subject to peer review and are not required to demonstrate proof of success through experiments and processes usually associated with scientific research.
Patent classification is used to classify or organize patents based on their features. A patent document usually has at least one or more patent classifications assigned to the document. Use the classifications to expand your search. Below are some patent classifications.
In force from January 2013. Replaces the European Classification (ECLA). Jointly managed by United States Patent and Trademark Office (USPTO) and European Patent Office (EPO).
Locarno classification "is an international classification used for the purposes of the registration of industrial designs." Available on WIPO site.
IPC "provides for a hierarchical system of language independent symbols for the classification of patents and utility models according to the different areas of technology to which they pertain." Provided by WIPO.
From United States Patent and Trademark Office (USPTO).
Note : From 2015, USPTO no longer actively assign USPC to utility patents. Plant and design patents will continue to be published with USPC symbols.
Here is a Search Strategy prepared by USPTO which may give you a clue to patent searching.
Classification
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