Finding embedded Linux
I searched the issued patent database, on 10/26/07, for titles, specifications, claims, or abstracts containing "linux" and "embedded" using the search logic ttl/(LINUX and embed$) OR abst/(LINUX and embed$) OR ACLM/(LINUX and embed$) OR spec/(LINUX and embed$) where $ represents a wildcard. This resulted in 1,445 hits. However, this included many patents discussing such things as embedded URLs and embedded images, which aren't really of interest for our topic.

By eliminating the specification from the search and limiting it to the title, abstract, or claims, I reduced the chaff, leaving only patents strongly related to Linux and embedded systems. Again, I searched the issued patent database for titles, claims, or abstracts containing "linux" and "embedded" using the search logic ttl/(LINUX and embed$) OR abst/(LINUX and embed$) OR ACLM/(LINUX and embed$). This resulted in just five hits.

I searched the pending patent publication database for titles, specifications, claims, or abstracts containing "linux" and "embedded" using the search logic ttl/(LINUX and embed$) OR abst/(LINUX and embed$) OR ACLM/(LINUX and embed$) OR spec/(LINUX and embed$). This resulted in 6,289 hits. However, like the issued patents, most of these weren't of interest. So, again I eliminated the specification from the search parameters to reduce the chaff.

I searched the pending patent publication database for titles, claims, or abstracts containing "linux" and "embedded" using the search logic ttl/(LINUX and embed$) OR abst/(LINUX and embed$) OR ACLM/(LINUX and embed$). This resulted in 56 hits.

Because patent application publications are left in the database even after the patent issues, you'll find some repetition of inventions between the issued patent and patent application databases (although the application and the patent often differ substantially after the examiner gets through with them). After eliminating the replication and remaining nonrelevant patents, only around 29 patents/publications were left. Table 1 shows some examples of relevant U.S. patents and publications related to embedded Linux as of 10/26/07.

The patent documents located reveal that a variety of companies/investors are involved with embedded Linux. There isn't one company that really dominates the list and several of them are foreign companies. So, if you work with embedded Linux, searching patents can provide you with a nice target list of companies.

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Most of these patent applications were filed in the 2002 to 2005 timeframe, although two were filed in 2000. Figure 1 shows a graph of the number of documents per filing year. Applications from 2006 aren't fully represented in the data due to the 18 month delay between filing and publication of the application. So the 2006 applications related to embedded Linux are likely much higher than represented by the data.

In summary, most of the patent documents related to embedded Linux located in this search were filed between 2002 and 2005. No one company dominates the list of assignees but, rather, several companies from across the world. The number of U.S. patent applications filed related to the subject has seen as generally upward trend over the last few years, indicating increased popularity. Finally, even though Linux is a free-software operating system, it would be wise to search the U.S. patent database before commercially using Linux in an embedded application. Of course, refer to a licensed patent attorney if there is any doubt.

Danny Graves is a freelance patent analyst, patent agent, engineer, college instructor, author, and inventor with two U.S patents. He was a finalist for the 2001 Charles C. Gates Award for Excellence. He has researched numerous inventions across a wide range of technologies. Graves can be reached at dannygraves@bellsouth.net.