DP2013-11

How Do Science and Technology	 Intersect in Complex Products?
An Anal ysis of LCD-Related Patents
Yoichi MATSUMOTO
Kiyonori SAKAKIBARA
Masaharu TSUJIMOTO
April 1, 2013

How do science and technology intersect in complex products?
An analysis of LCD-related patents 1

Yoichi Matsumoto
Kiyonori Sakakibara
Masaharu Tsujimoto

Abstract
In this paper we discuss liquid crystal displays as an example of “complex goods,” or products
composed of multiple constituent elements, in order to elucidate the linkages between science andtechnology. Exploratory analysis of bibliographic information from patents reveals two primarycharacteristics of such linkages in the field. First, although technology may not display strong
linkages with scientific findings over all, some scientific knowledge is highly valuable for patented
inventions. Companies in this field may be able to leverage scientific findings not used bycompetitors in order to produce more inventions. Second, because complex goods are based on anarray of constituent elements, players in the field have the option whether or not to pursue inventions
with strong links to science.

1. Motivation

Scientific knowledge has become increasingly important in various industrial sectors;
industries relying on science or for which basic sciences play a crucial role are called “science-basedindustries.” Typical examples of science-based industries are biotech and electronics(semiconductors, devices, etc.). The relationship between industrial technology and science isparticularly strong in biotechnology, as may be seen in sectors such as drugs, foods, chemicals,
bioinformatics and other fields utilizing large genome or protein databases, and biomechanics (Gotoand Odagiri ed., 2003，pp. 3–4).
1This work was supported by JSPS KAKENHI Grant Number 22330123.
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Science linkage is a measure of the strength of the relationship between scientific findings andindustrial technologies, and is quantified by the number of scientific articles cited per patent. In theUS, patent applications must include information on preceding patents and related scientific articles.
Failure by a patent applicant (inventor) or their representative to disclose such information on “priorart” may be considered intentionally misleading if the applicant knew or should have known that the
information was relevant (Murakami and Asami, 2004, p.63). Therefore, in the US patent application
bibliographic data contains preceding patents and scientific articles highly relevant to the invention
in question, and searching such references may reveal the scientific findings on which the invention
is based.

4.5
4
3.5
3

the US

2.5

Japan

2

Germany

1.5

France1

the UK

0.5
2005

2003

2001

1999

1997

1995

1993

1991

1989

1987

whole world
1985

0

1983

the number of papers cited perpatentFigure 1: Science linkage in the US patentsyear

Source: Kanda, Ebisawa, and Tomizawa (2007), p.334, Table 8-2-1. The data is based on
the Patent Board, “Global patent scorecard data years 1980-2006.”

According to a survey by the National Institute of Science and Technology Policy (NISTEP)(Kanda, Ebisawa, and Tomizawa, 2007), there is a trend towards increased science linkage in US
patents (Figure 1). Whereas bibliometric analysis reveals worldwide science linkage values of 0.30
in 1983 and 2.80 in 2006, the increase is greater in the US at 0.35 and 4.15 respectively, followed by2

the UK, France, and other countries. The increase for Japan is much smaller at 0.19 in 1983 and 0.66
in 2006. In other words, in the US science linkage increased by a factor of about 11.9, while in Japan
only by a factor of about 3.5. Although the worldwide pattern is one of increased science linkage, theextent of this trend varies significantly by country.

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agriculture, forestry,
and fishery etc.

10

medicine/veterinaryscience8

inorganic chemistry6

organic chemistry

4

2005

2003

2001

1999

1997

1995

1993

1991

calculation/measuring

1989

0

1987

microbiology/biochemi
stry

1985

2

1983

the number of papers cited per patent

Figure 2: Science linkages in seven areas (Japan)

year

basic electric elements

Source: Kanda, Ebisawa, and Tomizawa (2007), p.334, Table 8-2-1. The data is based on
the Patent Board, “Global patent scorecard data years 1980-2006.”

Kanda et al. (2007) compare science linkage in patents from Japan and the US in seven areas,
three with high science linkage values in international patents (microbiology/biochemistry, organic
chemistry, and medicine/veterinary science) and four with high numbers of scientific citations(Figures 2 and 3). These results show that science linkage differences between Japan and the US byindividual technical field mirror the significant overall differences by country. Science linkage
values are consistently high for microbiology and biochemistry: 1.36 versus 2.60 for Japan and the
US respectively in 1983, and 10.31 versus 31.06 in 2006. Japan increased by a factor of only about
7.6 compared to about 11.9 for the US, demonstrating not only lower absolute science linkage forJapanese patents, but also lower rates of growth compared to the US.
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35
30

agriculture, forestry,
and fishery etc.

25

medicine/veterinaryscience20

inorganic chemistry15

organic chemistry

10

year

2005

2003

2001

1999

1997

1995

1993

1991

calculation/measuring

1989

0

1987

microbiology/biochemi
stry

1985

5
1983

the number of papers cited per patent

Figure 3: Science linkages in seven areas (US)basic electric elements

Source: Kanda, Ebisawa, and Tomizawa (2007), p.334, Table 8-2-1. The data is based on
the Patent Board, “Global patent scorecard data years 1980-2006.”

Although science linkage varies according to country and field, science linkage values as awhole have dramatically increased from 1983 to 2006, both for individual countries and fields withincountries. This implies that scientific findings are increasingly important across countries andindustrial fields.
Science linkage in the US far surpasses that of Japan. Branstetter and Ogawa (2005) point out thatin the US, where growth in science linkage is particular predominant, patented inventions are more
likely to leverage knowledge created recently by university scientists. This trend is particularly
strong in bioscience-related disciplines. The rise of science linkage in the US is strongly influenced
by advances in bioscience-related fields (which they term the “bio nexus”) and the contributions totechnology for which these advances are responsible.
Advances in bioscience-related fields account for a large portion of the increase in scientificcitations in US patents. This makes drug-related industries and technological fields a natural subject
for investigating linkages between industry and science. Indeed, there has been abundant research in4this area (for example, Kato and Odagiri, 2012; Breschi and Catalini, 2010; Odagiri, 2006; Pisano,
2006; Gittelman and Kogut, 2003; Murray, 2002; Zucker, Darby, and Brewer, 1998; Henderson andCockburn, 1994; and Noyons, van Raan, and Schmoch, 1994). Mansfield (1995) points out thatscientific findings are leveraged in inventions in different ways according to technological domain.
He states that 27% of pharmaceutical products would have been significantly delayed without recent
academic research, but this figure is only 6% for electronics products. There has been research on
linkages between electronics and science (for example, Shirakawa, Furukawa, Nomura, andOkuwada, 2011; Shirakawa, Nomura, and Okuwada, 2010, 2009; Breschi and Catalini, 2010), but
biosciences remain the predominant subject for research into linkages between science and industry.
There is one crucial distinction in technological characteristics between some electronics fields
and bioscience- or pharmaceutical-related disciplines. Levin, Klevorick, Nelson, and Winter (1987)
studied the primary means by which innovators in a variety of industries extract exclusive profit
from their innovations. Of the 18 industry types which yielded the greatest number of survey
responses, only chemical-related industries (pharmaceuticals, plastics, inorganic chemistry, andorganic chemistry) and the petroleum refining industry scored patents as an effective source ofprofits at 4 or higher on a Likert scale of 1 to 7. Only the pharmaceutical industry consideredpatents the greatest alternative source of profits (product patents). Levin et al. (1987) provide two
explanations for why patents are highly effective only in the chemical and pharmaceutical fields inappropriating innovation. First, it easier to demonstrate the novelty of specific molecular structures
than it is to demonstrate the novelty of an electronic or mechanical part. Second, whereas molecular
structures can clearly be demonstrated as identical in order to prove patent infringement, the burdenof proof is more onerous for large-scale complex goods assembled from multiple components. One
further reason patents do not necessarily lead directly to appropriation of innovation in large-scalecomplex goods such as semiconductors is the trend towards cross-licensing among multiple
companies involving multiple patents (von Hippel, 1982).

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The efficacy of patents in appropriating the fruits of innovation clearly provides a first-moveradvantage for corporations. It is often much more difficult for other companies to invent somethingelse fulfilling the same function. Fleming and Sorenson (2004) state that science serves as a map ofsystematized knowledge, enabling inventors to more efficiently “combine highly coupled
components” in their combinatorial search for innovation. Discovering new scientific combinations
is crucial in technological areas which reward making and patenting inventions before thecompetition.
In contrast, many areas of electronics demonstrate low levels of appropriating innovation
through patents. First, competitors may either avoid infringing on existing patents by simply
inventing alternate mechanisms which fulfill the same role, or they may develop other key
technologies used in the same complex goods to use in cross-licensing agreements. Therefore,
although companies will strive to outpace their competitors in terms of inventions and patents, there
are various other creative ways of gaining advantage as well. This means that science linkage willplay a different role in electronics than in biosciences or pharmaceuticals, which are more often
considered typical science-based industries. Corporate strategy should reflect these differences aswell 2.

1. Teece (1986) points out that complementary assets such as production facilities and sales networks
become key factors in securing profits when there is low appropriability of innovation. In otherwords, greater appropriability of innovation through patents tends to advantage venture companies,
which do not have the same access to complementary assets as larger companies. While it isinherently difficult for venture companies to enter areas such a biotech and pharmaceuticals becauseof the high-level R&D required, interaction between such industrial technologies and universities
enable venture companies to leverage university research, which effectively lowers barriers to entry.
These fields have high appropriability of innovation through patents. These two combinations spur
university scientists to make patent applications, and the dramatic rise of scientific paper citations in
bio-related patents may be because these scientists are highly knowledgeable about the scientific
literature. (It may also be true that university-affiliated scientists and corporation-affiliated scientists
exhibit different tendencies with regard to maximizing or minimizing the scientific literaturereferences they include in patent applications.) This means that interaction between industrial
technology and university research may not result in university-based ventures or more patentapplications from university scientists in areas with low appropriability of innovation. This suggeststhat scientific literature citations in patents in these fields may not raise to the same level as for bioand pharmaceutical-related patents.
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Case studies on two different products performed by the authors are particularly illuminating
regarding this point.

Panasonic’s purchase of Plasmaco: Japanese electronics manufacturer Panasonic developed
direct current (DC) plasma TV technology in the 1990’s, but rival Fujitsu developed alternating
current (AC) versions which became the standard technology in the market. Most US companies hadceased plasma TV development, leaving only a single venture company in the field, Plasmaco.
Cashflow problems were forcing Plasmaco to the brink of bankruptcy, and the company placed its
entire future on the line in developing new AC plasma technology. The company displayed the newtechnology at an academic conference in the hope that it would help secure funding to allow thecompany to survive. It was here that someone from Panasonic saw the new technology on display,which lead to Panasonic’s purchase of Plasmaco after studying their technology in depth. Plasmaco’s
patents ended up serving an important role in subsequent patent negotiations between Panasonic andFujitsu; the successful cross-licensing agreement enabled Panasonic to make rapid advances in the
AC plasma TV market (Sakakibara, Tsujimoto, and Matsumoto, 2011, pp. 59–79).

Kaneka’s bringing solar cells to market: Kaneka is a Japanese chemical manufacturer, one ofwhose main divisions is solar cells. This sets the company apart in Japan, where most solar cellmanufacturers are electronics companies. Kaneka sent research staff to Osaka University in 1980 toinvestigate possibilities of entering the solar cell market, but at this point the company was already alate entrant in the industry. The company had made a startling success in inventing amorphoussilicon solar cells, but this innovative technology alone hardly compensated for its latecomer status
in entering the marketplace. The company made presentations at many academic society meetings inorder to increase its name recognition and appeal to potential customers. This resulted in Casio
becoming interested in the company, and Casio approached Kaneka about jointly developing
ultrathin solar cells for its new credit card-type calculators. By responding rapidly and developing
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solar cells suited to Casio’s needs, Kaneka was able to successfully enter the solar cell market(Sakakibara et al., 2011, pp.92-109; Matsumoto, 2011).

These are only two examples, but they amply demonstrate the significance for companies ofcontact with the world of academic science. To summarize, academic societies play an importantrole in helping companies acquire new technologies or search for new directions in developing theirown technologies. In other words, academic societies function as a locus of knowledge aggregation.
Taken one step further, our theory shows that there is no single correct answer in combining themultiple technological elements that comprise complex goods, and academic societies serve as a
medium allowing one candidate solution of many to emerge. These solutions do not emerge
naturally, but as the result of efforts by those concerned (in this case employees of Plasmaco and
Kaneka) who are aware of the merits of academic societies. As a result companies which had
suffered from delayed starts gained momentum, and we see that crucial technological elements for
Panasonic and Casio were actually developed by Plasmaco and Kaneka.
It is difficult to use indicators such as science linkage to quantify the function of academic
societies and corporate activities striving to utilize these. The reason for this difficulty is that,
according to cases we have studied, the knowledge exchanged at such societies is not necessarily inconcrete forms such as papers or articles. Indeed, even inventors of a given technology may be
unaware of business implications that are clear to someone hearing about their invention. Therefore,
although detailed case-based research does have a significant role to play, some form of comparative
methods or indicators are required if the goal is elucidating differences according to nation,technology or industry in the linkages between science and industry. This raises the question ofwhether or not the type of technological differences we are interested in will be reflected in publicmaterials allowing for comparisons according to nation, technology, and industry. Given these issues,
we decided to use liquid crystal displays (LCDs) as a case study of complex goods and evaluate
patent data in a multidirectional framework.
8This study uses LCD patents and their bibliographic data on scientific literature to study
science linkage and time lag until citation. Science linkage is defined as the number of scientificreferences cited per patent, and is a representative indicator of the strength of connection between
science and industry. Closer relationships between scientific results/findings and industrial
technologies in science-based industries should be reflected in shorter time lags between scientificpublishing and those results being utilized in patents. It may also be the case that inventors may
apply for patents before publishing scientific results in order to secure rights. Either way, closer
relationships between science and industry should result in shorter time lags between scientificpublishing and patent applications. Our goal is to elucidate characteristics of scientific literature
citations in patents by comparing them with characteristics of preceding patent citations. Finally, wewish not to propose a new indicator for measuring linkages between science and industry, but to use
the existing well-known indicator from a different perspective in order to investigate the new
analytical possibilities.
Below we first provide background behind LCDs as an example of complex goods, anddescribe the datasets used in this study. Next, provide in-depth analyses of science linkage followedby time lag until citations. Finally, we discuss the implications of these findings for the intersectionof science and industry in the context of complex goods, and touch upon future developments.

2. Scope of analysis and summary of data

The subject of our research on complex goods consisting of multiple constituent elements isliquid crystal displays (LCDs). While liquid crystals were discovered in Europe, the fundamental
technology for using them in displays was developed in the US, while Japanese companies
industrialized the process (Numagami, 1999). In the 2000s LCDs gained popularity in use forlarge-screen TVs, but it was Korean and Taiwanese manufacturers which took the lead in this market.
This demonstrates the idea that LCDs have low appropriability of innovation; companies first to9

develop technologies do not necessarily reap the greatest profits from those innovations. LCDs
consist of many elements: liquid crystal materials, glass substrate and thin film transistor (TFT)
elements, color filters, polarizing plates, backlights, driver ICs, and more. Manufacture requires
knowledge of a diverse array of fields, including mechanics, chemistry, physics, and electronics(Suzuki, 1998; SEMI color TFT LCDs Revision Committee, 2005). All of these characteristics make
LCDs an appropriate subject of our study.
Our dataset was patents registered with the US Patent and Trademark Office (USPTO) as
provided by Thomson Innovation, a Thomson Reuters service. Thomson Innovation also allows
access to patents from the EU, Japan, and other countries, but we limited our analysis to patents fromthe largest market (the US) alone in order to eliminate potential confounding discrepancies
according to national patent systems.

We identified LCD-related technologies with Derwent

Manual Codes, a proprietary method of classifying patents in the chemical and electronic fields
manually input by Thomson Scientific specialists according to consistent criteria. We searched forcode category names including “liquid crystal” or “LC,” then narrowed our search to display-related
categories in order to select patents for analysis. Specifically, we included patents assigned any of
the following codes: L03-G05A (liquid crystal display devices), T04-H03C2 (LCD), U14-K01(liquid crystal displays), and W03-A08B (liquid crystal display). In 2001 the US instituted an early
publication system for patents, but we restricted our analysis to patents which were actually granted.
Our final data set consisted of 8767 patents identified according to the above methodology on July13, 2011.
Figure 4 shows LCD-related patent applications over time. Available data begins in 1979,
during which 5 LCD-related patent applications were made. This number increased to a temporary
peak of 90 in 1985, at which point they experienced a decline. Applications began increasing again,
however, numbering 125 in 1991 and 455 in 1995, which was another peak year. Applications
stagnated again in the late 1990s, but then began a dramatic increase in the 2000s, reaching an
all-time high of 815 in 2001. Applications appear to stall gain from the mid-2000s, but the time lag
10from application to granting makes it difficult to determine the meaning of the drop-off ofapplications after 2006. There remains a strong trend of increases of LCD-related patents during theperiod in question, with three noticeable peaks in 1985, 1995, and 2001. These peaks likely coincidewith increased development efforts during periods in which LCDs were adopted for use incalculators and watches, notebook computers, and TVs.

Figure 4: The number of LCD-related patents

the number of patents

900
800
700
600
500
400
300
200
100
0
application year

Figure 5 shows the ratio of total patents according to region (Japan, US, EU, Asia excluding
Japan, and other regions). Japanese patents account for 80% of the total in 1979, but only 5 related
patents were granted this year, so this number is not very significant. Japan’s share of patents
increased in the 10 years from 1980 to 1989. After declining in 1990 and 1991, Japanese share again
increased to 60% in 1992, after which they decline gradually to 40% in 2006. US share declined
dramatically in the 1980s, then maintained a steady range of 20–40%. Share of Asian countries
excluding Japan (“Asia”) began increasing from the mid-1990s, and have exceeded 30% in the
2000s. Meanwhile, the EU had share of more than 10% in the 1980s, but this decreased dramaticallyfrom the 1990s forward. LCD-related patents granted by the USPTO originate almost exclusively
from these four countries and regions.
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100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

OthersEuropeAsia
the US
Japan
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011

share

Figure 5: Regional shares of the numbers of patents

application year

Figure 6 shows regional shares of citations in patents, or how many times a given patent iscited in subsequent patents. As explained above, US patent law mandates inclusion of relevant prior
art in patent applications. Greater citations in subsequent patents is an indicator of influence on
subsequent technological development, which is a proxy for higher value. Therefore, Figure 6 may
also be considered to illustrate the value of patents produced by various regions. The figure reflects
all citations in patents granted at the time of database search.
First we see a strong surge in citations of Japanese patents beginning in the 1980s. Japan’s
ratio of patent citations begins the decade with about 20% in 1980, but climbs to near 80% by 1986.
Japanese patents accounted for about 70% of all related patents in 1986, so the value generated bythese patents somewhat exceeded their absolute number. Citations of Japanese patents fell to the 40–
60% range in the 1990s, during which time the share of Japanese patents granted also stagnated.
However, from 1992 to 2006 Japan’s share of patents fell to 40% only in 2006, while the country’s
share of citations fell to 40% five times during the same period (1999, 2002–2004, and 2006).
In contrast, the US’s share of patent citations fell dramatically in the 1980s together with its
share of patents awarded, while from the 1990s forward its share of citations (20–50%) have been12

slightly higher than its share of patents. Further, although the share of patent citations belonging to
Asia begins to rise from the mid-1990s, this share is lower than patent share in more years than not.
In these figures IBM patents are counted toward US totals because the company, listed aseither patent applicant or assignee, is a US corporation. However, many inventors of IBM patents
residents of Japan. For this reason we analyzed the figures including IBM patents in Japan’s share,
but this did not alter the fact that US patens had a higher citation rate than absolute share.

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

OthersEuropeAsia
the US
Japan
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011

share

Figure 6: Regional shares of citations in patents

application year

Now we shall summarize the two types of patent share described above for Japan, the US, andAsia. First, in the 1980s Japan rapidly expanded its share of patents awarded, while also increasing
the value of those patents as seen through citations. Japan’s share of patents stagnated overall in the
1990s and beyond, while its share of citations shrunk even further relative to the absolute numbers ofpatents. Even though Japan made great strides in the 1990s, the quality of its patents suffered in the
1990s forward. Second, in the 1980s the US suffered a severe decline of both patents awarded andshare of citations. Thereafter the number of US patents stabilized, although at a low share, while its
share of citations has been larger in proportion than the number of patents awarded. In other words,
the US has been successful in producing high-value patents despite the absence of LCD
13

manufacturers in the country. Third, although the number of patents applications awarded to Asia
has increased through the 1990s and 2000s, citation share has remained relatively low for thesecountries, showing that quality has not kept pace with quantity of patent applications.
Next we analyze science linkage and time lag to citations.

3. Measuring Science Linkage

Measuring science linkage requires analyzing the scientific literature in the “Other References”
section of patents. This section lists all references other than patents, and includes a wide variety ofmaterials from scientific papers to books and corporate technical reports or manuals. Therefore, wemust find a way to narrow references in this section to include only scientific literature that serves as
a valid measure of science linkage. Narin et al., who have researched issues related to sciencelinkage in depth, use a method which involves comparing items listed in Other References to the
Science Citation Index (SCI), and extracting only those references which also exist in the SCI(McMillan, Narin, and Deeds, 2000; Narin, Hamilton, and Olivastro, 1997). We used the same
methodology to identify scientific literature cited in LCD-related patents. Specifically, we used five
databases in Thomson Reuters’s Web of Science: Science Citation Index Expanded(SCI-EXPANDED), a database of natural science literature; Conference Proceedings Citation
Index–Science (CPCI-S); Social Sciences Citation Index (SSCI), a database of social science
literature; Arts & Humanities Citation Index (A&HCI); and Conference Proceedings Citation Index–
Social Science & Humanities (CPCI-SSH). We manually identified relevant references according tojournal name, paper title, author, and page listed. This process was performed by three research
assistants, and was checked by one of the authors.
This process resulted in 3279 scientific papers referenced by 8767 patents for a sciencelinkage value of about 0.37 for the period in question. There were 16903 citations in Other
References in our sample, about 19% of which were identified as scientific papers. Figure 7 shows14

science linkage by year of patent application, a figure which fluctuates significantly across time.
Science linkage is only 0.2 for patent applications made in 1979 (one scientific literature citation
across five patents), while the figure climbs to about 0.63 in 1986. It falls again to about 0.28 in
1991, then fluctuates wildly between about 0.3 and 0.5 until 2003, after which it climbs rapidly toabout 0.59 in 2007. As observed above, the time lag from patent application to granting means thatour data set does not contain patent applications made in recent years. This makes us hesitant todraw any significant conclusions about the significant decline from 2007 onward, but we can statethat 1) science linkage varies across time even within the field of LCD-related patents, and 2) there
are no consistent trends to be observed with regard to either increases or decreases.

the number of papers cited perpatentFigure 7: Trend of the science linkage of LCD-related patents
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0

application year

Figure 8 shows science linkage across time for Japan, the US, Asia, and the EU. Japan’shighest year is about 0.5, while most years vary within the 0.1–0.3 range. US patents have higher
science linkage than Japan’s in almost all years; in particular US patent science linkage spikes oncein 1985 and then rises again after 2000. Asian countries have lower science linkage than Japan. EU
countries have low absolute numbers of patent applications in the field, making it difficult to15

interpret fluctuations in science linkage. However, we can observe multiple dramatic rises. It is
instructive to observe the differences between Japan and the US, the two countries with the greatest
number of related patents. Scientific linkage of Japanese patents is consistent but at a low level,
while US patents fluctuate much more wildly, but at a higher level overall.

2.5
2
1.5

Japan
the US

1

Asia

0.5
0

Europe
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011

the number of papers cited perpatentFigure 8: Science linkage across time for Japan, the US, Asia, and the Europe

application year

Before examining the distribution of scientific papers cited, we first examine the distributionof patents cited. In Figure 9 the vertical axis shows number of patents, while the horizontal axis
shows the number of patents cited. A total of 569 patents cited 6 existing US patents, while morethan 500 patents cited 4, 7, or 8 patents each. The shape of the distribution may be described as a
distorted single peak.
Figure 10 shows the distribution of patents citing scientific papers. It shows that theoverwhelming majority of patents do not cite scientific literature at all. A total of 7692 patents cite
no scientific papers, or 88% of the total. Meanwhile, 483 patents cite one paper, followed by 233
patents citing two papers. In contrast to the distorted single peak distribution of patent citations
above, this graph tapers off gradually, demonstrating that distributions of patents cited by other16

patents differ qualitatively from the distribution of scientific papers cited by patents. Finally, thegreatest number of scientific papers cited was 51.

Figure 9: The distribution of the number of patents citedthe number of patents

1000

100

10

0
10
20
30
40
50
60
70
80
90
100
110
120
132
144
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341
555

1
the number of patents cited by patents

Figure 10: The distribution of the number of papers citedthe number of patents

10000
1000
100
10
1

0

2

4

6 8 10 12 14 16 18 20 24 28 32 48
the number of papers cited by patents

Next we change our viewpoint to the cited scientific literature itself. Figure 11 shows how
many times each paper is cited by patents. The vertical axis shows number of papers and thehorizontal axis the number of citations each paper was given by the patents in our sample. Of the173279 scientific papers in this sample, only 13 were cited 13 or more times, while 1160 (35%) were
only cited once. This graph shows the same gradual decline in Figure 10 above. It would be
instructive to repeat the analysis for other technical areas to determine whether or not the 35% of
scientific papers cited only once is relatively low or high.
Figure 11: The distribution of the times each paper citedthe number of papers

10000

1000

100

10

1

0

5

10

15

20

25

30

35

the number of citations each paper was given by patents

40

Our study does not evaluate the overall diversity of scientific literature cited by LCD-related
patents, but we may narrow our focus to study the issue. Specifically, we analyzed the distribution ofscientific literature citations in patents of companies either currently or previously engaged in the
LCD market. One possibility is that similar research goals may lead such patents converge on similarscientific findings more than our data set as a whole. Conversely, competing organizations may seek
to gain an edge by pursuing development along divergent scientific and technical lines.
We analyzed patents from the following ten companies: Fujitsu, Hitachi, IBM, LG Display,
Mitsubishi Electric, NEC, Panasonic, Samsung Electric, Sharp, and Toshiba. We limited our search
up to 2002 in order to eliminate confounding effects due to the time lag from patent application to
granting. There were 1423 patents from these companies during the period in question, all of which18

cited 189 scientific papers a total of 264 times. This results in a low science linkage value of about
0.13.
Do similar aims in R&D and patent acquisition of these LCD manufacturers result in more orless overlap in scientific papers cited? Figure 12 shows the distribution of scientific literature citedby the patents in question. We see that 151 papers were cited only once, which at 57% is a greater
ratio than the data set as a whole. This indicates a greater diversity of scientific literature citations
among the subset of patents belonging to LCD manufacturers alone.
Figure 12: The distribution of the times each paper cited by major LCD companies

the number of papers

1000

100

10

1

0

2
4
6
8
10
12
the number of citations each paper was given by patents

However, Figure 12 also includes instances in which multiple patents from the same company
cite the same scientific paper multiple times. This makes it impossible to judge whether or not thissubset of patents truly demonstrates diversity of scientific references. Therefore, we eliminatedoverlapping references from the same company and analyzed the data again to see if different
companies still tended to cite the same scientific papers. First, for comparison, Figure 13 shows
overlap between companies in terms of patents cited by patents belonging to major LCD
manufacturers. Eliminating multiple citations by the same company, we see that 6542 patents werecited by patents in question. Of these, 5496 (84%) were cited by only one company, while 767
19(12%) were cited by two companies. The two patents cited by the most companies were cited by 10
and 7 respectively.
Figure 13: The overlap between companies in terms of patents cited
5496

767

1

2

203

56

11

7

2

3

4

5

6

7

Note: Actual numbers above bars mean the variety of patents cited, those under bars
mean the number of companies
Figure 14: The overlap between companies in terms of papers cited
173

15
1

2

1
5

Note: Actual numbers above bars mean the variety of papers cited, those under bars
mean the number of companies

20Figure 14 shows the same analysis with regard to scientific literature. After eliminating
multiple citations by the same company, we see that 189 papers were cited overall. Of these, 173(about 92%) were cited by a single company alone, 15 were cited by two companies (8%), and one
was cited by five companies. Thus, there is more diversity and less overlap in scientific literaturecited in patents by multiple companies. Whereas 84% of patents were cited by a single company
alone, 92% of scientific papers were cited by patents of a single company.

Figure 15: The times of citations made of each patent which were cited by one company

4873

406
1

2

136

23

23

23

8

2

1

1

3

4

5

6

7

8

9

12

Note: Actual numbers above bars mean the number of patents cited, those under bars
mean the times patents cited.

Overlap among cited scientific literature was extremely low even among LCD manufacturers.
A scientific paper cited by only one company has low value for other companies; in other words, it isvaluable only to the company whose patent actually cites it. We examined citation trends to elucidate
influence of scientific papers cited only once on the companies making the citations. First, Figure 15
shows the number of citations made of each patent from Figure 13 above which were only cited by asingle company. These patents, which were deemed valuable as sources of information only by one
company, were used for this this purpose by those companies only once in the overwhelming
21

majority of cases. These patents were cited only once in 4873 instances (89%), twice in 406
instances (7%), and three times in 136 instances (2%).
Figure 16: The times of citations made of each paper which were cited by one company
151

14
1

7

2

3

1
6

Note: Actual numbers above bars mean the number of papers cited, those under bars
mean the times papers cited.

Next, Figure 16 shows the same analysis with respect to scientific literature citations insteadof patents. Scientific papers were cited only once in 151 instances (87%), twice in 14 instances (8%),
and three times in 7 instances (4%). As with patents above, the great majority of scientific papers
cited by a single company alone were cited only once.
These results point to a subtle but interesting trend. First, there is more diversity in scientific
literature cited by LCD manufacturers than in patents cited: 92% of scientific papers were cited by asingle company compared with 84% of patents. However, there is less overlap in scientific papers
cited than in patents. If we consider sources of information cited only a single company to bevaluable sources of information specific to that company’s needs, then scientific literature fulfills
this function more often than patents. Further, most patents (89%) or scientific papers (87%) cited bya single company were only cited once, although there is less overlap among patents. In other words,

22

of patents and scientific papers serving as valuable sources of information specific to only certain
companies, the latter are more likely to be cited by multiple patents. From these findings, we
speculate that: first, scientific literature may be a better source of information specific to their needs
for companies than patents; and second, of patents and scientific papers serving as sources of
information specific only to certain companies, papers are slightly more likely to impact multiple
future patents.
To summarize our results thus far, LCD-related science linkage has varied in the range of 0.3
to 0.5, although it has risen to about 0.6 several times. Although rising trends are visible for somesubsets such as specific countries or patent types, there is no general rise overall. Japan and the US
are the two leading patent assignees, but the two countries exhibit differing characteristics: sciencelinkage in Japan has remained consistently low, while it has been much higher in the US and rising
rapidly in recently years.
Analysis of citations of scientific literature shows a diversity of papers cited rather than a few
major papers being cited by many patents. Further, the ratio of scientific papers cited only once ishigher for the LCD-related field than for our dataset as a whole, indicating that competingcompanies base their inventions on a diverse array of literature. Narrowing the dataset to LCD
manufacturers, scientific papers cited only by a single company are more common than patents cited
only by a single company. However, of scientific papers or patents cited by a single company alone,
single citations are more common for patents than scientific papers. In other words, scientific papers
or patents not cited by competing companies are cited only once in the majority of cases, and there isa slightly higher ratio of the former leading to more inventions.

4. Measuring the Citation Time Lag

In this section we will discuss the time lag between the publication of cited scientific papers
or patents, and citations of these made in patent applications. There is a significant difference
23between January and December of any given year, but difficulties in obtaining scientific literature
data force us to calculate time lag in terms of years. We refer to time lag to cited scientific literature
as “paper lag” and to cited patents as “patent lag.”Figure 17 shows time lag data for our entire dataset. Paper lag for the first year available,
1979, is only one year, but as stated above this year had a very small sample size and so is notmeaningful. The sample size is much larger for 1983, a year in which mean paper lag jumped tomore than 10 years before declining to four years in 1984. Lag increases dramatically again from1989 to 1990 and from 1993 to 1994, while falling dramatically from 1997 to 1998. Approximate
5-year means from 1985 onward are as follows: 1985–1989, 6.8 years; 1990–1994, 9.7 years; 1995–
1999, 9.6 years; 2000–2004, 9.8 years. The mean rises to 13.9 years in 2005–2009, but the fact thatdata before patents are awarded is not included could be warping the data. In contrast, the patent lag
is relatively stable at about six years. It increases to eight years in 1990, but then declines gradually
to about 4.7 years in 2000. In 2000 patent lag begins to increase significantly, mirroring paper lag,
until it hits about 11.7 years in 2009. Patent lag is shorter than paper lag in all years since 1985 withthe exception of 1985 and 1989.
Figure 17: The trend of time lag
20
18
14
12
10
8

paper lag6

patent lag

4patent application year

24

2009

2007

2005

2003

2001

1999

1997

1995

1993

1991

1989

1987

1985

1983

0

1981

2
1979

time lag (year)

16

Next we evaluate the distribution of time lag. Figure 18 shows patent lag distribution. The
existence of negative time lags is due to the long periods until patents are granted. We were able toidentify year of publication for 97143 patents cited in LCD-related patents. Patent lag was highest at
two years (8823 patents), followed by one year (8611 patents), three years (8143), and zero years(7851). The longest patent lag was 141 years (2 patents). This figure also shows a single peak
distribution distorted to the left.
Figure 18: The distribution of patent lag
the number of patents cited

10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
-11
-4
3
10
17
24
31
38
45
52
59
66
73
80
88
96
103
110
120
134

0
the length of patent lag

Figure 19: The distribution of paper lag

the number of papers cited

300
250
200
150
100
50
0

-3 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 51 55 58 68

the length of paper lag

25

Figure 19 shows the paper lag distribution. As with patents above, the existence of negative
time lags is due to long periods required for receiving patents; or, in the case of scientific literature,
papers may have been published after obtaining patents. Of the 3279 scientific papers in this data set,time lag was four years for 254, followed by two years for 248, three years for 235, and five years
for 231. The longest time lag was 69 years for one paper. As with the patent citation time lag above,
this shows a single peak distribution distorted to the left. Although patents and scientific literature
exhibited different science linkage distribution profiles, there was no such difference for time lag.
Figure 20: Patent lag in Japan and the US
18
16
time lag (year)

14
12
10
8

Japan

6

the US

4
0

1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009

2

application year

Next we examine paper lag of the two prime patent-producing countries, Japan and the US.
Figure 20 shows the patent lag, which we examine as a comparison to paper lag. Patent lag varies
within the time period in question. Lag rises in the US around 1983 and from the late 1980s to theearly 1990, then trends upward gradually beginning in the 2000s. In Japan patent lag rises in the late1980s and from the early 1990s to 1995, then trends upward gradually in the 2000s in a patternsimilar to the US. Of particular interest is the fact that the US had a shorter patent lag than Japan
only once in the 20 year period from 1985 (when the sample size increased) to 2004. This suggests

26that Japanese patent applications are based on more recently-granted patents than US patentapplications are.
Figure 21 shows the same analysis with regard to paper lag. The overall trend for both Japanand the US is increasing lag from the 1980s to the first half of the 1990s, followed by stabilizationfrom the mid-1990s for the next decade or so. Paper lag for the two countries remains relatively
close from 1985 to 2004, with shorter paper lag in the US than Japan in 10 out of 19 years (there isJapanese data for 1990). However, paper lag is shorter in the US for 7 out of the final 10 years (1995
to 2004).

Figure 21: Paper lag in Japan and the US
25time lag (year)

20
15
Japan

10

the US

2009

2007

2005

2003

2001

1999

1997

1995

1993

1991

1989

1987

1985

1983

1981

0

1979

5

patent application year

Comparing patent lag and paper lag in the period from 1985 to 2004 shows that while patentlag varies in the 4–8 year range, paper lag varies in the 6–10 year range. This demonstrates that ingeneral patents are used more rapidly than the scientific literature as a source of information forfurther inventions. Further, Japan has shorter patent lag than the US. This fact may be due to thetechnological excellence of Japanese manufacturers, which were the driving force behind large-scaleindustrialization of LCDs. There is no clear pattern in comparative durations of paper lag between
the US and Japan. In contrast, in the second half of this period the US was more proactive in27

leveraging new scientific findings in its patents, indicating that US inventions in the field are morestrongly tied to the latest science. This mirrors overall recent trends in science linkage, which has
been rising dramatically in the US remaining stable at a low level in Japan.
Our analysis thus far has focused on the time lag from publication of a patent or scientificpaper to citation in a patent. Next we turn our attention to the duration for which patents or scientificpapers continue to be cited after the first citation. In other words, what is the lifespan of utility ofpatents or scientific papers for new inventions? We can imagine two possible patterns: one in whichscientific results rapidly lead to new inventions before becoming irrelevant; or, scientific findings
may build cumulatively, with older sources maintaining their relevance and being continuallyreferenced. The first pattern would result in higher science linkages associated with shorter time lags,
while the second pattern should result in the reverse.
To study the issue, we first identified the set of patents or scientific papers which were cited atleast once from 1985 to 2004, but not cited from 1979 to 1984 (earliest period for which data isavailable) or from 2005 (the year patent applications began declining) forward. We then calculated
the number of years from first to last citation, which we consider the “lifespan of utility” of thesepatents, and plotted the mean lifespan of utility against year of publication.
Figure 22 shows mean lifespan of utility for patents and scientific papers published from 1980
to 1999. The mean lifespan of utility for patents in 1980 was about 1.0 years, although thislengthened during the 1980s until reaching about 2.1 years in 1988. Thereafter the utility lifespan ofpatents declines consistently, with the exception of a rise in 1992. In contrast, lifespan of utility for
scientific literature was about 1.8 years in 1980, a figure which then declines rapidly until reaching
about 1.5 years in 1985 and then rising again to about 1.4 years in 1989. Utility lifespan for scientific
literature then begins a long consistent decline in 1990 forward, falling about 0.2 years in 1998
onward. Comparing the two, lifespan of utility is longer for patents than for scientific literature in all
years after 1985.

28

Figure 22: The trends of mean lifespan of utility for patents and scientific papers

2
1.5
paper

1

patent
0.5
0

1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999

mean lifespan of utility

2.5

application year

Figure 23: The trends of mean lifespans of utility for patents and scientific papers excluding thosecited only once
8
7
6
5
4

paper

3

patent

2
1
0

1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999

mean lifespan of utility

9application year

The great majority of cited patents and scientific papers are cited only once, resulting in alifespan of utility of 0 years. Taking simple means of the data therefore distorts our perspective, so
Figure 23 shows the same data excluding patents and scientific papers cited only once. Excludingthese data points does result in larger mean values, but overall trends and relationships between
patents and scientific literature remain consistent. However, this figure does show a more29

pronounced tendency for decreased utility lifespans for patents when compared with scientificpapers.
To summarize, scientific paper lag is as follows: 1985–1989, about 6.8 years; 1990–1994,
about 9.7 years; 1995–1999, about 9.6 years; 2000–2004, about 9.8 years; and 2005–2009, about
13.9 years. In contrast, patent lag was relatively stable at about 8 years from the 1980s to 2000, after
which it increased dramatically. The wide variation in paper lag up until 1985 makes it difficult todetermine whether patent lag or paper lag was longer during this period, but after 1985 patent lag
was consistently shorter. Comparisons of Japan and the US show that whereas patent lag is shorter inJapan most years, paper lag is largely equivalent between the two countries. However, paper lag was
shorter in the US for seven years in the period from 1995 to 2004, showing that recently the US has
been more successful than Japan in leveraging new scientific findings in inventions.
Further, analysis of lifespan of utility for patents and scientific literature, or the number ofyears from first to last citation, shows that utility gradually lengthened for both until around 1990,
after which it began shrinking. However, eliminating patents or scientific papers cited only a single
time results in changes in observable patterns. Specifically, the trend of gradual lengthening until
around 1990 becomes clearly observable only for patents, while for scientific literature only thetrend of shrinking from around 1989 remains. We consider it highly interesting that the lifespan ofutility has been shrinking in recent years (from around 1990, that is), even if this trend does emerge
from data from which patents and scientific literature cited over the long term have been excluded.
Also of interest is the fact that scientific literature published in nearly all years has a shorter lifespanof utility than patents published in the same year. Combined with the time lag data above, it becomesapparent that there is a longer time lag for scientific literature from publishing to actual use ininventions, and that the duration of said use is shorter as well compared to patents.

5. Discussion

30

In this paper we have evaluated science linkage through the lens of LCD-related patent
information. We specifically selected this industry as an example of complex goods, a category
which has not received significant treatment in such discussion to date.
Traditionally, bioscience-related disciplines have been the focus of research studying linkages
between science and industrial technology, as these fields are clearly heavily dependent on science.
At the same time, these fields exhibit high appropriability of innovation through patents. In contrast,
appropriability of innovation through patents is lower for electronics, a field which has not played as
major a role in study of science linkage. Large-scale, complex products have been noted for theirtendency towards low appropriability of innovation. Because they consist of multiple constituent
elements, there is no single technological element playing a pivotal role within the system. This
makes it easier to avoid conflicts with existing patents and is a reason for the prevalence ofcross-licensing. This results in a state of affairs in which successfully creating and patenting acomplex goods-related invention does not necessarily lead to significant income from that
innovation. We focused on patents related to complex electric goods in the hopes of elucidatingsome latent characteristics in the relationship between these system-based products and sciencelinkage, not merely out of a desire to measure the closeness of their relationship with science. We
arrived at three major conclusions through our analysis of US patent data.
First, overall science linkage trends vary according to time period even among the field of
LCD-related patents, and there is no obvious pattern of rise or decline. Further, Japan and the US,
which are the two major countries in terms of patent applicants and assignees, display differingcharacteristics: Japan is stable at a low levels, while the US fluctuates more but at a higher level. In
particular, science linkage in the US has increased dramatically from around 2000 forward.
Second, analysis of distribution of scientific literature citations in patents shows that theoverwhelming majority of patents cite no scientific papers. Whereas the most common number ofpatents cited in other patents is six, the most common number of scientific papers is zero, with 87%
of patents citing no scientific literature. Of all the scientific papers in our dataset, 1160, or 35% of31the total, were only cited once. This figure rises to about 57% if we restrict the set to patents held bymajor LCD manufacturers. In other words, overlapping of cited scientific literature decreases among
competing companies. A total of 84% of patents cited in patents of major LCD manufacturers arecited by only a single company, while this figure is 92% for scientific papers. Of references cited byonly one company, 89% of patents were cited only once compared to 87% of scientific papers. In
other words, this means that of all patents or scientific papers cited by one out of the ten major LCD
manufacturers examined here, slightly more scientific papers contributed to multiple patented
inventions. These reveal that scientific papers are more likely to function as source of knowledge
specific to certain companies, and that this company-specific knowledge is somewhat more likely tolead to multiple inventions for scientific literature than for patents.
Third, our analysis of time lag shows a general trend of longer periods for scientific literaturethan patents from publication to being referenced in patents. This time lag until use in inventions islonger for scientific literature than for patents in every year since 1985 with the exception of 1985
and 1989. The difference in lag time widened in particular in the late 1990s. Japanese patent lag isconsistently shorter than the US; comparisons show that patent lag was shorter for US than Japanese
patents in only one year from 1985 to 2004. In contrast, the US shows shorter paper lag for 10 years
out of the same 20 year period, seven years of which occurred in the last ten years. In other words,
while Japanese tend to more rapidly utilize findings from industry in generating new innovation, theUS tends to more rapidly utilize findings from the world of science, a trend which is particularly
pronounced from 1995 forward. The fact that Japanese are more adept at using latest technologies togenerate new innovation may be due to the fact that Japanese companies actively engaged in themarketplace may be better positioned to leverage existing technologies in inventing new ones. In
contrast, the US’s success in leveraging the latest scientific findings may reflect a preference for
utilizing science for inventing LCD-related technologies, an interpretation consistent with ourfindings related to science linkage. Another interesting finding was that the length of time bothpatents and scientific papers were referenced in later inventions began falling overall from around32

1990. Although it must be remembered that patents and scientific papers referenced for extremely
long durations were excluded from the data set, and it is difficult to make certain statements within
the context of this research, our observations suggest that the useful lifespans of both patents andscientific literature are shortening.
What do these facts mean for the linkage between LCD-related technologies and science? The
first obvious implication is that the linkage in the field between science and industry is notparticularly strong. Most patents refer to no scientific papers at all, and science linkage in patentsfrom Japan, the country which lead expansion in the area, has remained stable at a low level.
Comparison of time lag also shows that new knowledge arising from the sciences is slower to be
adopted than new knowledge from technical sources, and it is used for a shorter period of time. The
above observations allow us to draw two tentative conclusions about the intersection of science andindustry in the context of complex goods.
First, as may be surmised by points one and two above, companies seem to have pursued
scientific findings not leveraged by competitors in order to secure their own company-specificsources of knowledge. Narrowing the focus to major LCD manufacturers shows that scientificpapers are more likely than patents to be cited by specific companies alone. In this way, science
serves as a better tool for companies to differentiate their sources of knowledge. We also see thatscientific papers not used by other companies are slightly more likely to be leveraged in multiple
patents than patents not cited by other companies. In other words, although the LCD-related
technology field as a whole seems to maintain distance from the latest scientific findings, companies
have been successful in utilizing science by identifying papers they alone leverage. However, the
88% of related patents not citing any scientific papers speaks to the fact that, in most cases, scientificfindings are hardly crucial for invention in the field. These factors contribute to a state in which LCD
manufacturers must find the rare pieces of scientific knowledge suited to their own particulardevelopmental needs, even if science as a whole does not fulfill a crucial function for them. Because
complex goods consist of multiple constituent elements, there is no single technological element33

playing a pivotal role within the system. Therefore it is reasonable to assume that utilizing scientific
literature for company-specific sources of information in order to differentiate their products in themarket place is a valid corporate strategy. This also implies that the best-known scientific findings
may not help companies differentiate their inventions from their competitors. In the domain ofcomplex goods, inventions based on widely-known scientific findings may have inherently
compromised value.
Second, as stated in 1 and 3 above, companies appear to have a choice when selecting sourcesof information in order to obtain competitive advantage. While Japanese companies successfully
contributed to large-scale industrialization of LCDs, their patents have consistently demonstrated alow level of science linkage. At the same time, they have shorter patent lag times, using existing
patents more readily to spur new innovation. In contrast, the US boasts fewer patents than Japan interms of absolute number, but the frequency with which US patents are cited speaks to their highlevel of overall quality. Science linkage of US patents has not only been high overall, but it has been
increasing dramatically in recent years. US patents also demonstrated shorter time lag than Japanese
patents from publication of scientific literature to citations in seven out of the ten years between
1995 and 2004. These facts indicate that while the US is no longer active as a manufacturer of LCDs,
US companies have increasingly turned to science as a source of knowledge for innovation.
Complex goods consist of an array of constituent elements, each of which has its own technologicaland scientific background. Japanese companies have largely selected a path for innovation ofutilizing the latest technologies, while US companies have chosen a path of utilizing the latest
science. Different options exist even within the same field for sources of knowledge to form thebasis for inventions.
Our analysis of LCDs as an example of complex good using patent data has demonstrated two
main patterns with regard to the linkage between science and industry in the context of complex
goods. First, although the linkage between science and the field is not particularly strong, companies
may strive to differentiate themselves from competition by identifying scientific findings unused by34

the rest of their competitors and leverage these through multiple inventions. At the same time, in thecontext of complex goods it is likely much more difficult to identify such useful scientific findings
compared to fields with closer relationships between science and industry. At the same time, there isa choice within this environment whether or not to pursue inventions strongly based on the latest
science. This leads to coexistence of products within the same category based on, or not based on,
the latest scientific findings. There may be no simplistic answer as to which approach is more likely
to lead to higher-quality products, at least for this type of industry. Indeed, sources of competitive
strength may differ qualitatively according to whether a given company pursues innovation based on
the latest technology or science.
These conclusions are based on the exploratory research performed in this study. We haveexamined a particular form of complex goods here, but further research is necessary to draw
comparisons with other forms of complex goods as well as non-complex goods.

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