US Patent Number Search

US patent number search refers to doing a typical patent search but by using only the patent number assigned to the invention. US patent number search is best done by doing a search on International Application Number. If it is a foreign patent number you may be able to locate it at the International patent site like the European Patent Office. Unfortunately, U.S. patents prior to 1976 cannot be searched other than by patent number or current classification.

There are several different ways of doing US patent number search on the web. Indexes for the patents were published in the Patent Gazette of the United States Patent and Trademark Office (USPTO) but are not presently available on the USPTO site for years prior to 1976. Patents were indexed yearly by Patentee, Subject, and Patent Holder.

With the patent numbers in hand you can go to the USPTO web site, enter the number and view and download the patents.  Suppose the date is 11-12-04. Patents are issued on each Tuesday of the month, and you will not find that date listed for 1904. There are two possibilities, either the date is incorrect or it is not a U.S. Patent. Assuming the 11-12 portion is correct you can look at other nearby years to see in which years patents were issued on Nov. 12 (one possibility is 1907). Also check similar-looking numbers, an 8 could be a 3 or a 6, a 1 could be a 7 or even a 4. If the patent date is valid and there are no patents that seem to relate to the item you have, perhaps the patent was not indexed under the subject.

Detailed information and links to the various patent web sites can also be found on the S&E Finding Patents web page. The two major patent web sites recommended by the S&E library are the Delphion Intellectual Property Network and the United States Patent and Trademark office (USPTO). The Delphion site contains a database of complete patents from 1974 until the present in an image format, plus some patents issued during 1971-1973.

The following tasks are necessary in conducting US patent number search:

1. select an appropriate patent web site
2. recognize a patent number
3. search by US patent number search at the Delphion Intellectual Property Network or conduct US patent number search at the USPTO web site
4. view the results of your US patent number search
5. order copies of the patent
The importance of US patent number search could be underestimated. US patent number search could serve as your ground in filing a patent application.