Patents

Tips and tricks for online searching historical patents, from before 1970, with a focus on old calculating devices.

For recent patents and patent applications better online search tools and strategies are available.

In the mid 1990s I started collecting mechanical calculators. It seemed a good idea to use patents to get more information on these machines. In the still fledgling World Wide Web a few patent numbers of old calculators, such as the Curta, were listed. There was also a rudimentary website of the United States Patent and Trademark Office (USPTO, http://patft.uspto.gov/) where patents from 1976 and later could be found. That was not very useful for mechanical calculators. Fortunately I lived close to the library of the University of Delaware, which doubles as a state library and therefore contains a huge collection of federal government documents. This library had microfilms of U.S. patents. That way I could make photocopies of interesting patents if I knew their number. At that time I bought a Comptometer, which had a shield with some of patent dates, but no numbers. Since U.S. patents are published only once a week, on a Tuesday,[1]  that meant that I'ld have to look through a lot of patents of one publication day before I would have found the Comptometer patent. With bad luck, the patents of one day were taking up several film spools, each of which had to be requested at the library desk. Fortunately, next to the microfilm readers was a shelf with the paper version of the Official Gazette for Patents, in which a summary of patents is given per day and subject. With the Gazette patent numbers could be identified much faster.

I scanned and OCR'd a few interesting patents and placed it on my brand new website "Original Documents on the History of Calculators". This attracted the attention of a few European collectors who asked if I could add copies of other patents. It threatened to get out of hand...

U.S. patents online

Fortunately the USPTO was steadily improving its online presence. Images in TIFF format of all old patents were put on the web. They could only be found by Patent Number and Classification, and not by date, title, inventor or text. The Comptometer had already shown that the ability to search by date would have been convenient. So I made a tool that could estimate a patent number based on the publication date. The tool converted this estimate into a query of the USPTO database. When you added a classification to the query (for calculating instruments: 235/$), and the patent was issued in a time where not many patents were issued, you quickly located the required patent. Years later, Google came up with its own full-text search engine for U.S. patents, and relieved us from of those inconvenient TIFFs.

Europe

In the late nineties, I returned to the Netherlands. The library of the Dutch Patent Office in the European Patent Office in Rijswijk took over the role of the University of Delaware Library. It has paper versions of European Patents and Gazettes. In a French Gazette I found a reference to a French patent from 1855 for a "nouvelle machine à calculer et à imprimer des tables de mathématiques" granted to "Nits, comte de Barck". I did not recognize the name, and the title sounded interesting, so I looked up the paper version of the patent. The quire had never been cut open, but the bookbinder of the library helped me out, adding a free lecture about the quality of the paper. It turned out to be the "difference engine" invented by George and Edvard Scheutz. Nits, comte de Barck, was a Swedish adventurer, Nils Barck, who applied for the patent in his own name (well, an impressive variant of it).[2]  So I had not found an unknown inventor of a "machine à calculer et à imprimer des tables de mathématiques", but an ordinary case of fraud mistaken identity.

With the rising availability of patent information on the Web, the library opening hours were increasingly limited. The Library of the Netherlands Patent Office can now be visited by appointment only,[3] despite the fact that old patents and old gazettes not yet fully available online.  Fortunately, the Nits patent, FR13480, can now be found in the INPI database (search for "Barck")

Metadata

Data about the patent is called "metadata". I will list the main items.

Title

Depending on the country and the time the title can say a lot or very little. Complete titles are often missing in online databases.

Inventor

Apart from the name of the inventor, in paper patents the residence of the inventor is often indicated as well. In English and recent patents even the full address of the inventor or applicant is given. Databases usually do not provide this extra information. Sometimes even more biographical information about the inventor can be deduced, such as the year of death if the patent is handled by an executor. One can also track name changes, such as that of Eli Hyman Goldberg to Hyman Golber[4] around 1919 or John George Bricken to John Beaver[5]  around 1931.

Assignee or applicant

The applicant is the person or agency that applied for the patent, the assignee is the person to whom the patent was granted. This may be the inventor, but also a company or another person. Sometimes there are several persons or companies between applicant and "assignee", each passing the patent to another. U.S. patents call that "by mesne assigment." Take care with English patents: the databases often do not contain the true inventor or applicant, but a British patent attorney or agent.[6]  The actual applicant will be mentioned in the text.

Application Date

The date the patent was handed in at a patent office. French patents also stated the time of application with a one minute precision.

Publication Date

Application date and publication date usually differ by a couple of years. Publication dates show a pattern. U.S. Patents are published on Tuesdays,[1] French ones around the first and 15th of each month.

Issue Date

The date on which the patent takes effect is the issue date. In the United States, this coincides with the publication date, but in many European countries the issue date is some time before the publication date. In Germany the difference can be more than one year, which I do not understand. What should the inventor do? When he marketed his invention in the meantime, and someone else did the same, the other can not be accused of infringement, because he could not know the patent. When the inventor waits until publication, he looses one year.

There are no Dutch patents issued between 1869 and 1912.[7] 

Types of patents, patent numbers

Apart from the "ordinary" patents, called "Utility Patents" in the USA, a few other types of patents exist. In the databases different types can be recognized by different number formats. Different types usually have different search engines.

In international databases, an "ordinary" patent has an patent number comprising of a country code (US, DE, GB, FR, etc), a number and sometimes a letter. The trailing letter mimics the status of the patent document display (application, publication, abandoned). In most searches for old patents that letter is not relevant. An exception is Austria. AT{number} gives an entirely different patent than AT{number}B. Usually the B variant is interesting for mechanical calculator collectors because AT{number}B refers to patents between 1899 and 1994, and the letter-less version is more recent. And another exception is France. If a French patent is an addition to an existing patent, its number will with an E: FR{number}E. The numerical value has nothing to do with the number of the patent it is added to. A third exception is the German Gebrauchsmuster (DRGM). The Gebrauchsmuster in the European patent database end with U: DE{number}U.  A graph showing DRGM numbers versus year can be found at www.holzwerken.de

The United States has two special types of patent: the "Reissue" , listed in international databases as USRe{number}, and the "Design" which is listed as USD{number}. Both types have their own numbering. The number of a Reissue has nothing to do with the number of the original patent.

Most countries started once with patent number 1 and continued ever since. We have already seen that Austria restarted around 1994. Until 1916 the UK patent number restarted each year. In the databases English patents of at that time are listed as GB{year}{number}. The year is the year of registration and the number has at least 5 digits, starting with extra zeroes if necessary. In print the number would be GB{number}/{year}.

Japanese patent numbers started anew for each era: Meiji: year 1 = 1868, Taisho: year 1 = 1912, Showa: year 1 = 1926, Heisei: year 1 = 1989. Japanese patents are numbered in the database as JP{era-letter}{year}{number}B . Patent JP S47-23487B (for a planimeter) dates from the 47th year of Showa, so from 1972.

The numbers of patent applications usually start anew each year. In Germany, complex application codes were used, which often appear in the databases with additional prefixes. So far I have had little success searching old German patents by their application codes.

Classification

For the assessment of the novelty of a patent application one needs to quickly and easily compare it with existing patents. A good patent classification is essential for this task. Historically, there have been several national patent classifications. In 1971 an International Patent Classification was made, which has gone through several versions since then. The national patent databases went to great lengths mapping old classes to the new IPC. The IPC version that is currently used most commonly dates from 2006[8]  but the "core" IPC significantly adapts every three years to the latest technological developments. Fortunately collectors of mechanical calculators do not suffer from the latest technological developments.

Family

A patent family is a collection of patents for the same invention by the same inventors with equal priority but applied in different countries. Patents in a family are similar, but can vary in style and level of detail. Databases sometimes contain the full text of only one patent of a family.

References

A patent can contain two types of references to old patents: references by the inventor or applicant (often to its own patents ...) and references added by the patent examiner. In addition, references to technical literature can be made. U.S. Design Patents, which are only about appearances, often refer to sales catalogs. Weird associations have been made. For example, U.S. Design Patent USD148458 for a keyboard,[11]  refers to US2170153, a patent for a waffle iron.[12] 

Online Resources

When searching online for patents a single source is not sufficient. So I'll list some sources that complement each other.

Epilogue

The search for old patents can be frustrating: you know for example that a patent, or at least its application, should exist, because another patent refers to its application, but you can't find it because its metadata is missing in the databases. And once you found the patent, it might not help you in answering your question. A good example is Otto van Poelje's "Mystery D&P Slide Rule with Broken Powers"[15] The patent number "DRP 126499" on that slide rule refers to a general patent[16] on the construction of the slide rule, and says nothing about the mysterious scales.

Still, a lot of interesting information can be found in patents. Often you will be surprised by the ingenuity of the inventors, and sometimes by their naivety.

Notes