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Directorate for Social, Behavioral
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NSF 99-350  June 18, 1999
by Lawrence M. Rausch
International Patenting Trends in Advanced Materials: Ceramics

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Japan and the United States lead all other nations in the formation of international patent families involving ceramics technology.















Japan produced the greatest number of international patent families in this technology area, but the United States had the highest number of highly cited ceramics inventions.



This report is the third in a three-part series that examines America�s technological position vis-�-vis that of five other countries�Japan, Germany, France, the United Kingdom, and South Korea�in technical areas likely to be important to future economic competitiveness. The areas examined are advanced manufacturing, biotechnology, and advanced materials; the indicator used to determine a country�s relative strength and interest in these areas is international patent activity. To facilitate patent search and analysis, the three broad areas were each represented by a narrower subfield. This report examines advanced ceramic technologies as a proxy for advanced materials.[1]

International Patenting Activity
Tabulated by priority year, this indicator provides a first measure of the extent of each nation�s inventive activity. These patent family counts represent inventions important enough to be patented outside of the country of origin. During the first half of the 1990s, these six countries generated a total of 968 international patent families in the field of advanced ceramics. Annual totals varied from a high of 264 in 1990 to 134 in 1994, which is the last priority year available for this study (figure 1).[2] Patenting activity in this six-country group accounts for more than 90 percent of all families in this technology area.

Figure 1. Advanced ceramics technology: number of international patent families by priority year and country: 1990-94

Japan and the United States lead all other nations in the formation of international patent families involving advanced ceramics technology. Together they accounted for more than 70 percent of the total formed in the 5-year period examined. Japan held 39 percent of the total families formed during this period (381 international families); the United States held 32 percent (310 international families).

As used here, advanced ceramics are defined as ceramics (i.e., inorganic, non- metallic solids) with compositions not usually found in traditional ceramics. These compositions include oxides, carbides, nitrides, and borides, as well as aluminate, titanate, zirconia, and modified silicates.

The analysis is built around the concept of a patent family which consists of all the patent documents published in different countries associated with a single invention. The first application filed anywhere in the world is the priority application: it is assumed that the country in which the priority application was filed is the country in which the invention was developed. Similarly, the priority year is the year the priority application was filed. The basic patent is the first patent or patent application published in any of the roughly 40 countries covered in the database used (Derwent World Patents Index Latest ).

International patent families are used to mitigate bias introduced by national systems, such as Japan�s, that encourage large numbers of domestic patent applications. An international patent family is created when patent protection is sought in at least one other country besides that in which the earliest priority application was filed.

The three indicators used in this assessment are overall trends in international inventive activity, highly cited inventions, and the size of international patent families.


Highly Cited Advanced Ceramics Inventions
Interpatent citations are an accepted method of gauging the technological value or significance of different patents. These citations, provided by the patent examiner, indicate the �prior art��the technology in related fields of invention taken into account in judging the novelty of the present invention. The number of citations a patent receives from later patents can serve as an indicator of its technical importance or value. In fact, Carpenter, Narin, and Woolf (1981) have shown that, on average, technologically important U.S. patents receive twice as many examiner citations as does the average U.S. patent, reinforcing the validity of interpatent citation as an indicator of patent quality.

Of the 968 international patent families formed by the six countries during the 1990-94 period, 23 were considered highly cited inventions.[3] Japan generated the greatest number of international patent families in this technology area during the period, but the United States had the greatest number of highly cited inventions with 15 (or 65 percent of all highly cited international patent families). Japan was second with 4. When each country�s number of highly cited international patent families is adjusted to account for its overall volume of international patenting in this technology (citation ratio), the United States again leads all six nations. The United States had a citation ratio of 2.0�that is, U.S. inventors� share of highly cited international patent families was twice its share of the total international patent families formed during this period. Japan�s citation ratio, 0.4, suggests that the four highly cited international families it produced during this period were below the level expected given the total number of international patent families the country generated. The United Kingdom had only two highly cited international families, but exceeded expectations in this indicator with a citation ratio of 1.8 (table 1). France and Germany each had one highly cited international patent family; this again was below expectations given their respective shares of total international patent families in this technology.

Table 1. Advanced ceramics: International patent families, highly cited patent families, and citation rates, by selected priority country: 1990-94

Average International Patent Family Size
Given the significant costs associated with obtaining patent protection in multiple countries, the average international patent family attempts to measure the perceived commercial potential of an invention by adding a market-size indicator for each country in which patent protection is being sought.[4]

Based on an adjusted average international family size, the advanced ceramics inventions with the highest perceived commercial potential, on average, were produced in France; these were closely followed by those produced in the United States (table 2). The United States also had the second largest number of international patent families for the period examined. Japan, the most prolific inventor of advanced ceramics technologies during the 1990-94 period, trailed the United States and the large European nations in terms of average commercial potential for each invention. South Korean inventions showed the lowest commercial value based on this indicator: the country was at a relative disadvantage due to its small home market. Conversely, since most inventions are first patented in the country in which the inventor resides, U.S. inventions have an edge in the calculation for this indicator because of the large size of the U.S. economy. Using international patent families as the unit of comparison�as is done here�reduces this bias. Because of its market size, the United States attracts most commercially important inventions and is likely to be a member of many of the international patent families included in this indicator.

Table 2. Advanced ceramics technology: number of international patent families and average international family size: 1990-04

Summary of U.S. Position
Taken together, these indicators suggest strong U.S. inventive activity in advanced ceramics technology. Although the nation produced the second largest number of international patent families in this category during the period studied, its inventions were the most highly cited and had nearly the highest average commercial potential when compared with inventive activity in the other five nations.

Carpenter, M.P., F. Narin, and P. Woolf. 1981. �Citation Rates to Technologically Important Patents.� World Patent Information 1981: 160-63.

Claus, P., and P.A. Higham. 1982. �Study of Citations Given in Search Reports of International Patent Applications Published Under the Patent Cooperation Treaty.� World Patent Information 4: 105-9.

Mogee, M. E. 1991. Technology Policy and Critical Technologies: A Summary of Recent Reports. Washington, D.C.: National Academy Press.

Mogee Research & Analysis Associates. 1997. Comparing Assessments of National Position in Key Science & Technology Fields. Report prepared under National Science Foundation, Small Grants for Exploratory Research (SGER) Grant No. SRS-9618668. Washington, DC.

Narin, F., K. Hamilton, and D. Olivastro. 1997. �The Increasing Linkage Between U.S. Technology and Public Science.� Research Policy 26, No. 3 (December): 317-30.

National Critical Technologies Review Group. March 1995. National Critical Technologies Report. Washington, DC.

Office of Science and Technology Policy (OSTP). 1995. National Critical Technologies Report. Washington, DC: National Critical Technologies Panel.

���. 1997. Science & Technology Shaping the Twenty-First Century. Washington, DC: Executive Office of the President.

Popper, S., C. Wagner, and E. Larson. 1998. New Forces at Work: Industry Views Critical Technologies. Santa Monica, CA: RAND.

This Issue Brief was prepared by:

Lawrence M. Rausch
Division of Science Resources Studies
National Science Foundation
4201 Wilson Boulevard, Suite 965
Arlington, VA 22230
703-306-1777 ext. 6927
E-mail: lrausch@nsf.gov

SRS data are available through the World Wide Web (http://www.nsf.gov/statistics/). For more information about obtaining reports, contact pubs@nsf.gov. or call (301) 947-2722. For NSF's Telephonic Device for the Deaf, dial (703) 306-0090. In your request, include the NSF publication number and title, your name, and a complete mailing address.


[1] These data were developed under contract for the National Science Foundation by Mogee Research & Analysis Associates and cover the period 1990-94; they were extracted from the Derwent World Patents Index Database published by Derwent Publications, Ltd. The technology areas selected for this study met several criteria:

[2] The declining number of international patent families formed during the period does not necessarily indicate any drop in inventive activity. It may only reflect the younger age of these inventions.

[3] The data used here include all patent families with priority application dates from 1990-94 with four or more citations. The citation counts are those placed on European Patent Office (EPO) patents by EPO examiners, as the EPO citations are believed to be a less biased and broader source of citation than those of the U.S. Patent and Trademark Office. See Claus and Higham (1982). To adjust for the advantage countries with large numbers of international inventions would have on this indicator, a country�s share of highly cited patents is divided by its share of total patent families.

[4] The market-size indicator is a ratio of a country�s GDP to that of the United States valued in purchasing power parities at current U.S. dollars.

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