Patents
`Trade Marks
`Heading
`IP Law
`Hybrid car technologies –– what can the
`advanced patent analysis method
`Network Patent Analysis (NPA) tell us
`about the leading companies and
`patents?
`
`
`
` A
`
` joint report between Griffith Hack and its
`patent analysis partner Ambercite.
`December 2010
`
`
`
`Working With Clever People
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`2502378_1 (GHMatters) G83591
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`
`
`PAICE 2010
`Ford v. Paice & Abell
`IPR2014-00571
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`Ambercite White Paper 2010_1
`Hybrid car technologies –– what can an advanced patent analysis
`method such as Network Patent Analysis (NPA) tell us about the
`leading companies and patents?
`
`December 2010
`
`By Mike Lloyd and Doris Spielthenner,
`www.ambercite.com
`
`
`
`In conjunction with
`
`Exclusive Australian licensee of Ambercite
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`In conjunction with
`
`Exclusive Australian licensee of Ambercite
`
`
`Hybrid car technologies –– what can an advanced patent analysis
`method such as Network Patent Analysis (NPA) tell us about the
`leading companies and patents?
`Ambercite White Paper 2010_1
`
`Mike Lloyd, International Marketing Manager, Ambercite, mike.lloyd@ambercite.com(cid:3)
`(cid:3)
` IP Strategic Advisor, Griffith Hack, mike.lloyd@griffithhack.com.au
`Doris Spielthenner, Managing Director, Ambercite, doris.spielthenner@ambercite.com(cid:3)
`
`
`Executive Summary
`
`Network Patent Analysis™™ (NPA™™) is the sophisticated analysis and mapping of patent
`citation data for the purposes of determining the leading patents, patent applicants and
`technology trends in any area of technology. In this white paper NPA is applied to the area of
`hybrid car patents to illuminate the key developments.
`
`Analysing 58,000 hybrid car patents and their inter-relationships, we found that the top ranked
`patents were filed by the hybrid drivetrain developer Paice Corporation, ahead of patents filed
`by Toyota, Ford and Honda who are better known for selling hybrid vehicles. NPA was also
`used to illustrate the ‘‘apparent technology flows’’ (or similarities between patents) into and out
`of the top ten patents filed by these companies. The leading Paice hybrid car patents were
`shown to have strong self-citation relationships with other Paice patents. This contrasts with
`the top ten hybrid car patents filed by Ford, which were connected via citations to a variety of
`companies including Paice, Toyota, and Railpower Technologies, who have developed hybrid
`technologies for trains. Toyota’’s top ten hybrid car patents showed a strong citation
`relationship to patents filed by Suzuki as well as Paice, who has successfully asserted one of
`their key patents against Toyota in relation to hybrid vehicles.
`
`Overall, our study identified and visualised the most relevant relationships between leading
`patents filed by Paice, Toyota and Ford, which we found to be consistent with known litigation
`and patent licensing agreements between these parties, thereby helping to confirm the ability
`of NPA to predict potential patent assertions.
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`Contents
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`Contents .................................................................................................................................................. 3
`
`Introduction –– why analyse hybrid car patents? ...................................................................................... 3
`
`Application of Network Patent Analytics to determine patent quality ...................................................... 5
`
`What was the shape of hybrid car patent data structure, and what can this tell us? .............................. 7
`
`What were the leading hybrid car patents? ............................................................................................. 9
`
`What can NPA tell us about litigation in the hybrid car technology area? ............................................ 12
`
`Can NPA be used to show apparent technology flows between patent applicants? ............................ 14
`
`How do different patent applicants compare over their entire portfolio? .............................................. 18
`
`Acknowledgements ............................................................................................................................... 19
`
`References ............................................................................................................................................ 20(cid:3)
`
`ntroduction –– why analyse hybrid car patents?
`
`(cid:3) I
`
`Hybrid cars may end up changing the way we all drive. A hybrid car, in general terms, may be
`described as a car that obtains its power from two or more energy sources. Currently, the
`most common type of hybrid cars are those sold by Toyota, which use an electric motor to
`boost or completely substitute for short periods a petrol motor (known as a parallel hybrid
`because the engine and electric motor can work in parallel). Alternative hybrid car designs
`include limiting the role of the electric motor to boosting the power available from a petrol
`motor (Honda) or using a petrol motor simply to produce electricity for an electric motor, which
`directly drives the car (produced by Chevrolet, and also known as a series hybrid). In all three
`cases, one of the main reasons for the increased fuel efficiency of a hybrid car is that they are
`able to capture, and store as electric energy, the energy normally lost during braking.
`
`General trends in hybrid car patent filings
`
`Hybrid cars have been around since 1899, but it is only in the last 10 years that they have had
`significant commercial success. This history is reflected in the patent literature. While the first
`known hybrid car patent was filed in 1906, the number of patent filings was relatively low until
`around 1992, when Toyota made a public declaration to significantly reduce the fuel economy
`of its cars. As discussed in a 2009 Griffith Hack report on hybrid car filings, hybrid car patent
`filings exploded after this date, with patent filings led by Toyota, Figure 1, but supported by
`other Japanese car companies and Japanese suppliers to the car industry, Figure 2. By 2009
`43% of the identified hybrid car patents1 were filed by Toyota alone, in comparison to 8% filed
`by the US car industry and 7% by the European car industry (Figure 3). Toyota also
`dominated hybrid car sales in the later part of the last decade, with 77% of US hybrid car
`sales in 2007 and 2008 coming from Toyota or its Lexus subsidiary.
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`Figure 1. Summary of hybrid car patent family filing trends2
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`Figure 2. Car company patent filings are supported by patent filings by suppliers.
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`Figure 3. Relative filing proportions of different hybrid car applicants (hybrid cars filed by car
`companies)
`
`
`
`Altogether Griffith Hack identified around 58,000 patents in the 2009 study, which came from
`around 19,500 patent families.
`
`Section Summary –– A 2009 review of hybrid car patent filings by Griffith Hack showed that Toyota
`was by far the dominant filer of hybrid car patent applicants. Other Japanese car companies such as
`Nissan and Honda, as well as Japanese suppliers, were also strong filers. In comparison, the US and
`European car industry filed comparatively few patent applications.
`
`Application of Network Patent Analysis to determine patent quality
`
`Patent specialists are always quick to point out that while large patent portfolios can have
`clear commercial benefits, patent quality is also important. For this reason in late 2009 the the
`Griffith Hack hybrid car report also applied the newly developed process of Network Patent
`Analysis3 (NPA) to hybrid car patent data. NPA connects all identified patents to each other
`via their citations linkages (forward or reverse citations) and looks for the strongest
`relationships between patents, based on mutual citations. Patents that have the ‘‘strongest’’
`relationships to other patents (based on the number, strength and direction of direct and
`indirect citations) are thought to be the strongest and most important patents, or at least the
`strongest and most important patented inventions.
`
`The use of citations linkages to form networks can be distinguished from other patent
`landscaping methods, which instead form landscapes based on keywords. One of the big
`advantages of NPA compared to keyword patent analysis is that NPA has an inherent
`capability to rank patents as well as group similar patents. There is no inherent mechanism
`we are aware of to rank patents when using keyword clustering; instead a separate process is
`required. Other differences between NPA and keyword clusters are discussed in Table 1.
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`Table 1. Summary of differences between NPA citation based and word based patent mapping
`
`Feature
`
`NPA citation based patent mapping
`
`Text based patent mapping (Eureka,
`Themescapes etc)
`
`Principle of
`grouping
`Can the patent
`mapping rank as
`well as group
`patents?
`
`Precision
`
`Dependence on
`patent language
`
`Effect of synonyms
`(e.g. ‘‘box’’ vs
`‘‘carton’’)
`Objective vs
`subjective process
`
`Links and ranks patents based on citation
`linkages, including citations from linked patents
`
`Links patents based on common keywords
`
`Patent ranking is inherent in the NPA process
`
`Can be very precise. Most citations are provided
`by examiners who identify the closest patents to
`a given invention after a search process. So
`patents are naturally grouped with very similar
`patents
`Providing that examiners are able to recognise
`the relevance of patents in another language (i.e.
`via patent abstracts), there is no dependence on
`language
`Providing that examiners are able to recognise
`that synonyms refer to the same concepts,
`synonyms do not affect NPA
`NPA can be regarded as an objective means of
`combining what can be hundreds of thousands
`of subjective opinions, i.e. a ‘‘meta-opinion’’
`
`Keyword analysis has no inherent means of
`ranking patents
`
`Precision can suffer when trying to distinguish
`patents in a narrow field which uses similar
`keywords for patents for different inventions, for
`example different solutions for a common
`problem
`
`May not work for patents filed in another
`language where keywords are different
`
`Can be affected, unless all synonyms are known
`and used in the analysis
`
`Text based patent mapping is purely objective.
`
`When we applied NPA to the hybrid car patents, we found the unexpected result that the first,
`second, fourth and seventh strongest patents as determined by NPA belonged to the little
`known Paice Corporation in the US. Paice was founded in 1992 to develop and
`commercialise inventions in the hybrid car field, in particular inventions related to the systems
`needed to connect electric motors to conventional petrol powertrains. In 2004 Paice
`commenced hybrid car patent litigation against Toyota. In 2005 a US jury held that Toyota
`infringed Paice’’s US 5,343,970 patent, and in 2010 Paice and Toyota settled all outstanding
`matters in relation to this litigation. US 5,343,970 was the second highest ranked patent
`according to the NPA analysis, and this helped us gain confidence in the inherent worth of
`NPA.
`
`In the period since late 2009 Ambercite and its associate Griffith Hack have continued to
`develop NPA and its capability to analyse complex patent areas, including in relationship to
`infringement analysis. Many of these developments have come at the request of our
`commercial customers who have challenged us to push NPA into new areas, and we thank
`them for this. However, for obvious reasons, we are not able to share the results of these
`commercial studies.
`
`The purpose of this report is to revisit the ‘‘public domain’’ NPA data set and apply some
`recently developed NPA techniques to show the type of insights that can be achieved by the
`advanced NPA analysis of complex patent data.
`
`Readers of the 2009 report will recognise that we have repeated some of the material from
`the first report into this white paper, but it should noted that this report contains a significantly
`enhanced analysis of the leading hybrid car patents.
`
`Section Summary –– Network Patent Analysis can be used show the strongest patents in a
`technology area, and has given results that were consistent with patent litigation.
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`What was the shape of hybrid car patent data structure, and what can
`this tell us?
`
`The initial hybrid car patent search query searched for all patents where the words ‘‘hybrid’’
`and ‘‘car’’ were found within two words of each other. This search yielded about 58,000
`patents in total. This patent data set was extended by including all first order (forward or
`reverse) citations to these patents which were not included in this dataset, which increased
`the number of patents to around 72,000 patents. These patents were linked together into
`networks through their citation linkages. Altogether 295 networks were formed, and in addition
`there were 8,100 patents that were not linked to any other patents though known citation
`data.
`
`The largest of these patent networks contained 58,239 patents, and a review of the subject
`matter of patents within this network showed that this network referred to hybrid cars. The
`second largest of these networks contained 541 patents and appeared to be focused on
`hybrid filters. Similarly the third and fourth largest networks were focussed on other topics.
`For practical reason we decided to focus on the leading network of 58,000 patents, and
`discarded all other networks and the unlinked patents.
`
`This example demonstrates a useful feature of NPA, namely its ability to objectively separate
`large patents into distinctly separate subject areas.
`
`This leading network of 58,000 patents was reduced in its size to make it more meaningful by
`identifying the most strongly connected patents. As an example of this reduction, Figure 4
`shows the network of the leading 5500 hybrid car patents according to NPA, which shows that
`the patents form into a homogeneous cluster. Of note, the cluster becomes more tense
`towards the centre, showing a strong highly interlinked core of key patents.
`
`Figure 4. Network diagram of leading 5,500 patents in the hybrid car patent data set
`
`
`
`This homogeneous data structure is relatively unusual in NPA analysis. For example, Figure 5
`shows the network structure for the leading 1012 patents for a more mature engineering
`technology. The patents appear to be forming into ‘‘clusters’’. Investigation of the subject
`matter of the patents in these clusters showed that each of the patent cluster represented a
`separate aspect of the technology. In this example the leading clusters referred to the
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`composition of the material used in the engineering process, and different elements of the
`design of the engineering equipment applied in this technology.
`
`Figure 5. Network diagram of leading 1,016 patents in an engineering technology patent data set.
`
`Subsequent experience with other NPA patent network structures is starting to suggest that
`the degree of homogeneity of an NPA patent cluster may be indicative of one or both of:
`
`
`
`(cid:120) The breadth of the patents included in the patent search, with a more uniform structure
`suggesting a narrower spread of technology.
`
`
`
`[It should be noted that the breadth of the search is an important factor to consider when
`analysing patents using Network Patent Analysis. Some clients like to use NPA to provide
`a high level landscape overview of a commercial area, i.e. to identify the key clusters,
`their subject matter areas, and the key patents and patent owners in these subject matter
`areas. This can be compared to how people might use a map of a country to identify the
`key cities. Other clients like to zoom into a tightly defined area. They already know which
`subject matter areas are important to them, and they are mainly interested in the key
`patents and patent owners. This can be compared to looking at the street map for a city
`to identify tourist highlights. In fact the NPA process allows both types of search; NPA can
`start with a high level overview, and then the client can select area(s) of interest to focus
`in on, to bring more detail of the structure into the picture. This process of looking at
`technology area at different scales can be compared to the process of using the zoom
`function in Google Maps; using higher degrees of zoom to bring in additional detail hidden
`at lower degrees of zoom.]
`
`(cid:120) The degree of technology ‘‘maturity’’, i.e. whether dominant aspects of the technology
`have been able to emerge. The hybrid car space currently involves a variety of different
`solutions to the problem of how to build a hybrid car. A Toyota hybrid is different to a
`Honda hybrid, and both are very different to the way a Chevrolet hybrid works. While all
`three cars recapture energy normal lost during braking, the way that this energy is
`reconverted to mechanical drive is very different. Because of this, patent examiners may
`have been citing patents based on the problems to be solved (for example ‘‘how to build a
`hybrid car powertrain’’) as well as based on the different solutions to this problem.
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`Both of these factors may have explained the homogenous network structure in the hybrid car
`patent network. Accordingly, in the future we would expect hybrid car patent data set to
`become more heterogeneous as dominant technologies emerge, and patent examiners
`become more likely to cite patents referring to similar solutions as well as similar problems.
`
`Section Summary –– The relatively homogeneous NPA ‘‘patent structure’’ within the area of hybrid car
`patents suggests that this area is still maturing, with dominant technologies yet to emerge.
`
`
`
`What were the leading hybrid car patents?
`
`If we continue to zoom into on the structures shown in Figure 4, and add patent numbers and
`colour coding for leading patent applicants, we end up with the very most central patents in
`this data set, shown in Figure 6. Of note, these patents appear to be dominated by patents
`filed by the car companies Toyota, Honda and Ford, and the technology suppliers Paice
`Corporation and Equos Research.
`
`Some of the lines connecting these leading patents are thicker than others. A thicker line
`represents a stronger connection, as evidenced by the number of mutual citations, in the
`same way as the strength of a relationship between two colleagues can be partially predicted
`by the number of mutual friendships. These leading patents can also be represented in table
`form, Table 2.
`
`Figure 6. Leading patents at centre of hybrid car data set.
`
`
`
`
`
`NPA can also be used to list the leading patents filed by selected patent applicants. The ten
`highest ranked patents altogether are discussed in Table 2. The five leading patents filed by
`Paice are shown in Table 3, with the ten highest ranked hybrid car patents filed Toyota and
`Ford are given in Tables 4 and 5.
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`NPA
`patent
`ranking
`
`Table 2. Top ten hybrid car patents (all applicants) according to NPA analysis
`
`Patent
`number
`
`Priority
`year
`
`Summary of patented
`invention
`
`Owner
`
`# of
`forward
`citations
`
`Ranking
`according to
`forward
`citation
`count alone
`
`# of
`reverse
`citations
`
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`US
`6,209,672
`
`1998
`
`US
`5,343,970
`
`1992
`
`US
`5,806,617
`
`US
`6,338,391
`
`1995
`
`1999
`
`US
`4,351,405
`
`1978
`
`1991
`
`2001
`
`Paice
`Corporation
`
`Paice
`Corporation
`
`Equos
`Research
`
`Paice
`Corporation
`
`Hybricon
`Incorporated
`
`Toyota
`
`Paice
`Corporation
`
`114
`
`256
`
`103
`
`30
`
`142
`
`33
`
`49
`
`10
`
`1
`
`14
`
`280
`
`4
`
`238
`
`115
`
`174
`
`37
`
`18
`
`185
`
`15
`
`23
`
`216
`
`18
`
`Hybrid car with two electric
`motors, one connected to
`engine and one connected
`to car wheels
`Improved hybrid electric
`vehicle where both engine
`and electric motor power the
`car, and energy is capture
`via regenerative braking
`Control system for
`combining electric and
`motor power in transmission
`Electric motor coupled to
`turbocharged motor, and
`control system
`Engine driving one set of
`wheels, and electric motor
`partially powered by
`regenerative braking driving
`the other set of wheels
`Control system for electric
`motor powered by internal
`combustion motor or battery
`Hybrid only runs engine
`when high torque needed
`Controller for requesting an
`engine driven generator to
`top up the vehicle batter
`Controls battery level on
`hybrid drive according to
`navigation plans of drive
`Control system for a hybrid
`car including cylinder
`deactivation
`
`US
`5,428,274
`US
`6,554,088
`US
`5,264,764
`
`US
`6,470,983
`
`US
`6,943,460
`
`1992
`
`1999
`
`2002
`
`8 =
`
`84 =
`
`10.
`
`
`
`Ford
`
`Hitachi
`
`Honda
`
`70
`
`40
`
`4
`
`51
`
`171
`
`3374
`
`47
`
`21
`
`Table 3. Top five Paice hybrid car patents according to NPA analysis
`
`NPA patent
`ranking-
`(Paice ranking)
`
`Patent
`number
`
`Publication
`year
`
`1 (P1)
`
`US 6,209,672
`
`2001
`
`2 (P2)
`
`US 5,343,970
`
`1994
`
`4 (P3)
`
`7 (P4)
`
`174 (P5)
`
`US 6,338,391
`
`US 6,554 088
`
`US
`20030217876
`
`2002
`
`2003
`
`2003
`
`
`
`Summary of patented invention
`
`Hybrid car with two electric motors, one
`connected to engine and one connected
`to car wheels
`Improved hybrid electric vehicle where
`both engine and electric motor power the
`car, and energy is capture via
`regenerative braking
`Electric motor coupled to turbocharged
`motor, and control system
`Hybrid only runs engine when high torque
`needed
`Control of a hybrid vehicle so that the
`engine is only run under conditions of
`high efficiency
`
`# of forward
`citations5
`
`# of
`reverse
`citations
`
`114
`
`256
`
`30
`
`49
`
`11
`
`174
`
`37
`
`185
`
`216
`
`440
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`Table 4. Top ten Toyota hybrid car patents according to NPA analysis
`
`NPA patent
`ranking ––(Toyota
`ranking)
`
`Patent
`number
`
`Publication
`year
`
`Summary of patented invention
`
`# of forward
`citations6
`
`# of reverse
`citations
`
`6 (T1)
`
`12 (T2)
`
`16 (T3)
`
`18 (T4)
`
`33 (T5)
`
`35 (T6)
`
`48 (T7)
`
`48 (T8)
`
`50 (T9)
`
`51 (T10)
`
`
`
`US
`5,428,274
`US
`5,856,709
`US
`6,687,580
`US
`5,841,201
`US
`5,839,533
`US
`5,550,445
`US
`5,495,906
`US
`5,545,928
`
`EP 511,654
`
`US
`6,563,230
`
`1995
`
`1999
`
`2002
`
`1998
`
`1998
`
`1996
`
`1996
`
`1996
`
`1992
`
`2003
`
`Control system for electric motor
`powered by internal combustion motor
`or battery
`Connection/clutch between engine
`and electric motor
`Controller for switching between car
`engine and electric motor.
`Control system for selecting both
`engine and electric motor drive
`Controller for regenerative brake that
`applies normal brakes during heavy
`braking
`Controller for determining when to
`charge the batteries
`Controller for determining when to
`transmit engine power to wheels or
`generator
`Controller for balancing engine speed
`and generator load
`Use of regenerated energy from
`braking to heat catalytic convertor
`Controller for balancing the fuel
`injection for the engine and generator
`load
`
`33
`
`64
`
`5
`
`67
`
`81
`
`49
`
`82
`
`68
`
`44
`
`26
`
`Table 5. Top ten Ford hybrid car patents according to NPA analysis
`
`Summary of patented invention
`
`23
`
`17
`
`15
`
`15
`
`22
`
`14
`
`11
`
`13
`
`5
`
`20
`
`NPA patent
`ranking –– (Ford
`ranking)
`
`Patent
`number
`
`Publication
`year
`
`# of forward
`citations7
`
`# of reverse
`citations
`
`8 (F1)
`
`36 (F2)
`
`58 (F3)
`
`76 (F4)
`
`89 (F5)
`
`93 (F6)
`
`120 (F7)
`
`124 (F8)
`
`127 (F9)
`
`132 (F10)
`
`
`
`US
`5,264,764
`
`US
`5,713,425
`
`US
`5,820,172
`
`US
`5,291,960
`US
`5,255,733
`US
`5,345,761
`US
`6,581,705
`US
`6,427,794
`US
`6,553,287
`US
`6,196,344
`
`1993
`
`1998
`
`1998
`
`1994
`
`1993
`
`1994
`
`2003
`
`2002
`
`2003
`
`2001
`
`Controls the engine used to recharge
`the battery for parallel hybrid vehicles
`Hybrid powertrain that combines
`conventional engine and electric
`motors
`Method of operating hybrid car to
`combine electric and engine drive to
`minimise fuel cost
`Using surplus energy from
`regenerative braking to provide heat to
`car or occupants
`Cooling system for hybrid vehicle that
`can preheat engine prior to startup
`Use of electrical energy from braking
`or engine to heat catalytic convertor
`Method for starting a parallel hybrid
`powertrain
`Detects when a generator or electric
`motor has been demagnetized
`Controller for a hybrid powertrain to
`deliver maximum acceleration
`
`Controller for a hybrid powertrain
`
`70
`
`119
`
`81
`
`131
`
`67
`
`73
`
`14
`
`7
`
`14
`
`14
`
`18
`
`17
`
`24
`
`14
`
`19
`
`13
`
`22
`
`15
`
`16
`
`8
`
`Section Summary –– Paice Corporation filed the highest ranked patents within the hybrid car
`technology area, with Toyota, Ford and Honda also filing top 10 patents. The top ten patents filed by
`Paice, Ford and Toyota were reviewed and found to cover similar areas.
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`What can NPA tell us about litigation in the hybrid car technology area?
`
`In 2007 the United States Court of Appeals for the Federal Circuit affirmed that Toyota had
`infringed the Paice US patent 5,343,970 patent, which as previously discussed was the #2
`ranked patent in our dominant patent list.
`
`A question that has been asked of us is why Toyota was found to infringe the #2 ranked Paice
`patent (according to NPA) and not the #1 patent. The first and original answer to this question
`is that any patent ranking system, whether objective or subjective, can only ever be an
`estimate and the ranking needs to be considered as a starting point for further analysis. In this
`light, the #2 position for the Paice patent still provides solid support for the performance of
`NPA.
`
`The second and more recent answer to this question is that NPA does, in fact, predict that the
`#2 Paice patent is the more likely Paice patent to be infringed by Toyota.
`
`This can be explained by considering Figure 7 below. In this diagram, patent colors refer to
`different patent owners, but only for Paice, Toyota and Ford. The label on each patent refers
`to its rank within the portfolio of an owner and the publication date. For example P1 (2001)
`refers to the number 1 ranked hybrid car patent within the Paice portfolio, which was
`published in 2001.
`
`Figure 7. Leading patents at centre of hybrid car data set, but with arrows shown to indicate the
`direction of technology ‘‘flow’’.
`
`
`
`Note that arrows have replaced lines between patents linked by citations. The lines point from
`an earlier patent to the later patent that cites it, i.e. toward the forward citations for this earlier
`patent. While it can be difficult to prove outside of litigation, it is possible that a later patent
`applicant benefited from the knowledge disclosed by the earlier patent applicant, either
`indirectly (e.g. via publication of the inventions as new products or in the media), or more
`
`
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`directly by reading the patent application. This can be regarded as an apparent ‘‘technology
`flow’’. Technology flows can also be seen between earlier and later patents filed by the same
`applicant, and are likely to be actual technology flows as the patent owner applies knowledge
`from the earlier invention to the later invention.
`
`Technology flow can also be used as a simple predictor for patent infringement; a later patent
`applicant may possibly be using the invention disclosed by the earlier patent applicant to
`apply the invention claimed by the later patent, and so may, subject to the normal subjective
`analysis, need to take a license to use the earlier patent. The idea of using forward citations
`as the basis for infringement analysis is already known in the field of patent analysis.
`However, NPA empowers this concept by identifying the strong relationships (thicker lines)
`between higher ranked patents filed by the companies being investigated. Higher ranked
`patents are more likely to be more important inventions, and hence are more likely to be
`commercialised by the patent owner. This allows the infringement analysis to focus in on the
`most likely infringements. In practice a patent owner can be provided with a list of patents
`owned by an licensing target in an approximate order of potential likely importance of
`infringement (i.e. which potential infringements to investigate first).
`
`This principle is seen very clearly in Figure 8. The P2(1994) [US 5,343,970] patent filed by
`Paice Corporation has arrows pointing towards the T4 and T5 patents filed by Toyota, both
`published in 1998, suggesting an apparent ‘‘technology flow’’. These arrows are highlighted in
`Figure 8, which shows an extract from Figure 7.
`
`Figure 8. Suspected technology flows between the P2 Paice patent, and the T4 and T5 Toyota patents.
`
`
`
`From Tables 3 and 4, we know that these patents cover very similar technologies, Table 6.
`
`
`
`Table 6. Comparison of the subject matter of leading Paice and Toyota patents
`Applicant
`NPA patent
`raking
`
`Patent
`applicant
`
`NPA patent
`ranking
`
`Patent
`number
`
`Publication
`year
`
`Summary of patented invention
`
`Paice
`
`Toyota
`
`Toyota
`
`
`
`2
`
`4
`
`5
`
`2
`
`18
`
`33
`
`US 5,343,970
`
`1994
`
`US 5,841,201
`
`US 5,839,533
`
`1998
`
`1998
`
`Improved hybrid electric vehicle where both
`engine and electric motor power the car, and
`energy is capture via regenerative braking
`Control system for selecting both engine and
`electric motor drive
`Controller for regenerative brake that applies
`normal brakes during heavy braking
`
`It is also worth noting the Paice P1 and P3 patents are receiving an apparent technology flow
`from a number of the Toyota patents (T4 to T8), suggesting a) a potential infringement risk for
`Paice Corporation, and b) that these Toyota patents may be relevant prior art to P1 and P3.
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`Both suggestions would require a subjective patent attorney review to confirm these findings.
`It is also worth noting that Paice Corporation is not selling hybrid drive-trains, making this
`potential infringement much less likely in practice.
`
`Paice has also asserted its P2 patent against Ford in May 20108, but the parties settled on
`confidential terms in July 20109. Of note, P2 has solid green lines pointing to Ford patents F2
`and F3. Conversely, Ford patents F2 and F3 have arrows pointing to Paice patents P1 and
`P3, but once again Paice may avoid infringement issues by not selling hybrid drive trains.
`
`In 200510 Ford signed a license agreement for about 20 hybrid car patents held by Toyota, in
`return for Toyota licensing technologies for ‘‘nitrogen oxide emissions control, variable valve
`timing, and direct injection spark ignition from Ford’’. The fact that Ford chose to take a license
`from Toyota for their hybrid car technology is supported by Figure 8, which shows arrows
`pointing from Toyota patents T1, T6, and T8 to Ford patent F3. There is also an arrow
`pointing between Toyota patent T7 and Ford patent F2.
`
`On the other hand, there also appears to be a citation relationship between Ford patent F1
`(engine control for hybrid cars), and Toyota patents T1 (control system for electric motor for
`hybrid cars), T6 (controller for determining when to charge the batteries) and T8 (controller for
`balancing engine speed and generator load). There is also a weak arrow flowing from Ford
`patent F2 to Toyota patent P11 (US patent 5,873,426, which discloses the principles of
`altering gear ratios when running in hybrid or non-hybrid modes).
`
`Section Summary –– NPA was able to show that relationships between leading patents filed by Paice
`Corporation, Ford and Toyota were consistent with patent litigation and publicly available licensing
`agreements between these companies. For example, NPA showed how Paice’’s successfully asserted
`US patent US 5,343,970 had strong citation relationships with leading hybrid car patents filed by
`Toyota and Ford.
`
`Can NPA be used to show apparent technology flows between patent
`applicants?
`
`NPA can also be used to show the similarity between patents filed by different companies.
`This can in turn can be used to suggest ‘‘apparent’’ technology flows in and out of companies.
`This concept is best shown by way of example. In this analysis, NPA was used to perform the
`following analysis:
`
`a) The ten highest ranked patents for Ford, Toyota and Paice were determined;
`b) All direct citations (forward and