Justin Blows published the results of a recent study on his Clean IP blog regarding solar patent quality. The study focuses on Australian patentees in particular but includes data from other countries as well.
Blows and his colleague George Mokdsi, both of the Griffith Hack law firm, attempted to measure the quality of patents relating to solar power technologies by using the number of times a patent was cited during prosecution of subsequent patent applications as a proxy for patent quality.Â
The theory is that oft-cited patents are likely to involve foundational technologies that others in an industry may need access to. These patents also provide strong protection to the patentee by forcing later patent applications to reduce their scope of protection:
A patent that discloses a technology with strong foundational characteristics is likely to be cited during the prosecution of a latter filed patent that discloses incremental advances on the same technology. Often, the foundational patent will force down the scope of protection afforded by latter filed patents. Thus, patents with high citation counts generally provide broad and robust protection.
The analysis was restricted to U.S. patents and the data was retrieved from the U.S. Patent and Trademark Office. However, patentees from a number of countries were considered, including the U.S., Great Britain, Japan, Germany, France, Australia, Italy, China, Korea and Taiwan.
The study found that U.S. patentees have the highest quality solar power patents:
Patents from the US are on average cited the most, at 2.9 times per application. By this metric, US solar patents have on average the highest quality.Â
The study also notes trends in solar patent quality, with Japan’s quality increasing and the U.S.’s and Australia’s declining.
According to the study, the U.S. winner was U.S. Patent No. 6,297,539 (“‘539 Patent”), which was cited 181 times. The ‘539 Patent, issued October 2, 2001, is entitled “Doped zirconia, or zirconia-like, dielectric film transistor structure and deposition method for same” and lists Sharp Laboratories of America as the assignee.
The Australian winner was U.S. Patent No. 6,429,037 (‘037 Patent), cited 17 times. The ‘037 Patent issued August 6, 2002 and is entitled “Self aligning method for forming a selective emitter and metallization in a solar cell”.   The ‘037 Patent lists Unisearch Limited, a Syndey company, as the assignee.
