Every inventor should conduct, or at least watch, at least one hands-on patent search to fully understand and appreciate the process. Obviously, not everyone can visit the Patent and Trademark Office’s Public Search Facility in Alexandria, Virginia. If you can’t make the trip, you may inspect copies of patents at a Patent and Trademark Depository Library (PTDL), a nationwide network of prestigious academic, research, and public libraries. The USPTO does not have regional offices; it has the PTDLs. In addition to being research centers, the USPTO uses these as sites for outreach programs. For example, when the American Inventor Protection Act passed, officials put on seminars at the PTDLs to explain it to the intellectual property community.

PTDLs are the best deal in town. They provide the public with a local link to the USPTO, expert reference assistance, patent and trademark databases, seminars and workshops, and USPTO searching resources. Most of the services are offered for free or at a very low cost.

PTDLs continue to be one of the USPTO’s most effective mechanisms for publicly disseminating patent information. PTDLs receive current issues of U.S. patents and maintain collections of patents issued earlier. The scope of these collections varies from library to library, ranging from patents of only recent years to all or most of the patents issued since 1790.

The patent collections in the PTDLs are open to the general public, and I’ve always found the librarians very willing to take the time to help newcomers gain effective access to the information contained in patents. In addition to the patents, PTDLs usually have all the publications of the U.S. Patent Classification System, including the Manual of Classification, Index to the U.S. Patent Classification, Classifications Definitions, and Official Gazette of the United States Patent and Trademark Office.

At each PTDL, you can conduct a manual search using the computerized database, CASSIS. This permits access to the weekly USPTO publication, the Official Gazette. CASSIS is limited in its range and capabilities. If you do find relevant prior art through CASSIS, which is not always easy, the PTDL should be able to make copies off microfilm for you.

The complete list of Patent and Trademark Depository Libraries is in Appendix C. There’s no charge for you to search their patent collections. Because of variations among the PTDLs in their hours of service and the scope of their patent collections, be sure to contact the library in advance about its collection and hours.

As mentioned earlier, a PTDL branch may have a specialized collection. To see the inventory of what’s available, go to www.USPTO.gov and look under PTDLs.

Even though I live near enough to the Alexandria, Virginia, Public Search Facility, I often opt to do my work at the University of Maryland’s PTDL, located within its Engineering and Physical Sciences Library. Crowded with books and not much larger than a small meeting room, the library offers only a couple chairs. However, here I can do my search work and have access to a very extensive collection of technical publications outside the PTDL that I enjoy browsing for ideas and technologies. Such “extras” are not available at the main government facility, and I consider them a bonus.