AmberBlog

Marvell Semiconductor had a less than perfect Xmas last year, having had a $1.17 billion judgement against them for infringement of two patents held by Carnegie Mellon University, after a jury trial in Pittsburg.

The award was in relation to two patents that referred to complex algorithms used to convert signals into data, for example when reading the data on hard disc drives. When reading such data, the computer sees a stream of data - but which of this signal is the underlying information and which is noise?

To answer this question, the Italian born American engineer Andrew Viterbi developed the Viterbi algorithm, which is a means of determining the most likely explanation, i.e. the underlying information, that underpins the signal. And then went on to receive a national medal of science for developing this algorithm and co-found Qualcomm, among other companies.

The Viterbi algorithm works in part by forming a structure with branches. Initially it was assumed that the noise in the different branches was independent, but in some circumstances this noise is correlated and this can introduce errors in the final outputs. The two Carnegie Mellon patents claim a means of compensating for this correlated noise.

Claim 4 of US patent 6201839, (Filing year 1998, priority date May 1997, and which we will 'CM1' because it is the earlier patent ) covering: 

A method of determining branch metric values for branches of a trellis for a Viterbi-like detector, comprising:

selecting a branch metric function for each of the branches at a certain time index from a set of signal-dependent branch metric functions; and

applying each of said selected functions to a plurality of signal samples to determine the metric value corresponding to the branch for which the applied branch metric function was selected, wherein each sample corresponds to a different sampling time instant.

Claim 2 of US patent 6438180 (Filing year 1999, same priority date as CM1, hereafter 'CM2'), covers (when combined with its dependent claim 1)

A method of determining branch metric values in a detector, comprising:

 receiving a plurality of time variant signal samples, the signal samples having one of signal-dependent noise, correlated noise, and both signal dependent and correlated noise associated therewith;

selecting a branch metric function at a certain time index; and

applying the selected function to the signal samples to determine the metric values.

wherein the branch metric function is selected from a set of signal-dependent branch metric functions.

In response, Marvel claimed that these patents were anticipated by US patent 6282251 to Seagate, which also discloses the use of a Viterbi algorithm to read the data on a spinning hard disc drive, and where the noise on the different branches in the multi path is correlated, and not random. However Seagate, a competitor to Marvell, was apparently happy to support Carnegie Mellon in this dispute, providing an email from the inventor of it patent noting that the CMU invention went well beyond the current state of the art.

Whether the Seagate patent is valid prior art for two Canargie Mellon patents is a matter for the appeal for this case - and there is some commentary on the web which expresses strong opinions on this. However, we were intrigued to see what AmberScope patent searching could add to this case, starting with the links between Carnegie Mellon patents and Marvell. 

Citation links to Marvell Semiconductor

Carnegie would not had to look far for suggestions that Marvell may need to take a license to their two patents. As a simple example of this, the website Patentbuddy offers the ability to identify and rank companies that have forward citation links to their patents. For the CM1 patent, the leading owner of forward citations was Marvell with 13 forward citations, while CM2 had 24 forward citations from Marvell. Forward citation by themselves are not proof of infringement, but does suggest that the citing company is interested in and has invested in developing similar technology.

It is also worthwhile considering how the Marvel patents are connected to the Carnegie patents. The figure below shows an AmberScope network of the patents connected to the CM2 patent. Patents belonging to Marvell have been marked with green circles using the word 'filter'. 

As you can see, the patents connected by (mostly forward citations lines, which are green as opposed to the blue backward citation connections) to the CM2 patent fall into three main clusters. A cluster means that the patents have interconnections between them, as well as to the CM2 focus patent.

You can also see the Marvel patents are distributed mainly in the bottom right cluster, although some patents are found in the cluster on the left. This cluster of Marvel patents would suggest a number of patents filed for similar inventions by Marvel, which in turn suggests a technology investment by Marvel in this technology area. So an investigator in this area would be well advised to review this patents to see if they described a technology, which if being commercialised by the patent owner, may infringe other patents in this area.

Prior art search - the easy way?

Given the natural interest in this billion dollar duo of patents, we were intrigued to see what the citation data could tell us if there were other patents out there that: 

• Discussed the treatment of correlated noise in a Viterbi algorithm using a time delay
• Had filing dates prior to 1998
• Had not been previously identified as prior art for either of the Carnegie Mellon patents by the USPTO.

We have done this search in three ways:

1) Using line thicknesses  within AmberScope to suggest similar inventions - and 'exploring' onwards from there

The complexity of inventions such as this one puts a big onus on searchers, who may not be fully familiar with the underling technology. Which raises an interesting question - what if AmberScope could analyse the citation information to lead searchers to a potentially relevant, purely in a objective way? Which may never replace the hard and necessary work of drawing final subjective conclusions from reviewing a patent, but could suggest which patents most deserve further analysis.  

In fact this is possible by using line thicknesses in Amberscope networks. Consider the figure below, which shows the network associated with CM1. This network shows forward citations, backward citations, and ghost patents, which are indirectly connected patents that may be similar to the focus patent. 

If we zoom into the area around the focus patent CM1 (which is easy to do using a mouse wheel), it can be seen that the lines joining the patents are of different colours and thicknesses. The colours refer to the citation direction with respect to the patent being reviewed, in this case CM1. Green lines point to forward citations, and blue lines to backward citations. 

The line thickness refers to the predicted similarity of the two patents, which is calculated from other citation relationships in the wider network. In this, the thickest line is to the other Carnegie Mellon patent, CM2. This should not be surprising, as CM2 is a continuation in part patent of CM1.

But how can this be used to find prior art patents? CM1 has a filing date of 1998, and so we will filter out all all patents later than 1998 using the filing year circled below. Only a few patents are left, and all are backward citations. One line is slightly thicker than others, see below.

This patent is US5689532 (filed 1996), filed by Quantum Corporation and now owned by Seagate. This patent does not specifically mention correlation of white noise and does not appear to be a direct  disclosure of CM1 - this is not surprising, as being a known backward citation for CM1, CM1 may not have been granted if the Quantum patent was a direct disclosure.

However the value of the Quantum patent is it too has connections, in this case to some ghost patents to the CM1 patent. The strongest connection (by line thickness) is to US5949831 (filed 1997) filed by IBM and now owned by HGST Netherlands, a subsidiary of Western Digital. 

This discloses a similar technology, namely that "Colored (non-random) noise at the input of a PRML Viterbi sequence detector results in sub-optimal performance." using a matching delay circuit to provide a delayed PR4 Viterbi output signal.

2) Searching using ghost patents

There are various means of using AmberScope effectively. One of the more useful and innovative features of AmberScope is it ability to find ghost patent, which are defined by our system as 'second order' patents (patents connected to patents connected to a focus patent, or 'friends of friends') that have a series of good connections to first order (directly connected) patents. We think they are useful because they are 'new' information, and so possibly can be used an opposing party to request re-examination of a patent. Ghost patents can be easily identified in an AmberScope network as they are faded out and so 'ghost like' in their appearance, as shown in the figure below, and highlighted by a red circle.

Although there are two Carnegie Mellon patents, we can start our analysis with CM1. So what the ghost patents for this patent?

In the example below, all of these ghost patents have have given a relevancy score of 0 (purely to colour them green) and been added into the table below, which has been downloaded and formatted below. For comparison, we have also added the Seagate patent referred to above in this table.

One of these patents is the US5949831 patent identified earlier. As this technology is quite complex, technical specialists in this area may be required to confirm the ultimate relevance of this potential prior art to the two Carnegie Mellon patents.

As you can tell from Table 1, some of these ghost patent appear to disclose some of the key elements of Carnegie Mellon patents, yet have not been cited by the patent examiner. It is of up to the courts to decide whether these other citations are relevant to Carnegie Mellon patents, but this shows how quickly AmberScope can identify potentially relevant prior art.

A further observation from this table is that the two Carnegie Mellon patents do not have particularly high AmberScore values. CM2 has an "AmberScore" (a measure of network connectiveness) of 4.4, which is 4.4 times the average AmberScore for US patents granted in the last 20 years. 4.4 is obviously better than average, but would not ordinarily predict a billion dollar infringement.

Marvell have made a similar point on their website, noting that the 50 cent per chip royalty failed to consider the:

'value attributable to that (patented by Carnegie Mellon) functionality, as opposed to other improvements.....more than 80 additional features were added at the same time that the (patented) feature was added.'

Obviously any such statements released by a litigant in the middle of litigation are likely to reflect the view and interests of the litigant. However this simple analysis would suggest that the Carnegie Mellon patents are not the most important in this 'neighbourhood', either in absolute (4.4 is not that high an AmberScore value) or relative terms (there were more dominant patents in the immediate neighbourhood).

$1.1 billion seems to me to be a very high royalty payable on a duo of patents that are far from dominant in their space.  It will be interesting to see how the appeal plays out.

 3) Using the already identified Seagate patent as the basis of an AmberScope search

Another option for the prior art search could be to start an AmberScope search from the already identifed Seagate patent US6282251. A preliminary search on this patent admittedly failed to identify anything directly relevant, but we did not fully explore this area. This still remains an option for searchers closer to this case to pursue.

 Conclusions

This blog has reviewed a pair of Carnegie Mellon patents that have been litigated against Marvell Semiconductor. AmberScope was used to identify some potential prior art, and provide some perspective on the relative value of these patents. Overall, notwithstanding the complexity of the technology and value of hard disc drives, this analysis has suggested that the billion dollar infringement cannot be supported by the relative dominance of these patents. We await the appeal with interest

What does a half billion dollar (and counting) quartet of patents look like?

VirnetX have just had their $336 million patent judgement against Apple for the use of their Facetime product upheld. This comes on the back of recent wins against Microsoft ($200m) and Siemens - and VirnetX are going back for another bite from Apple, as well as launching a $258 million lawsuit against Cisco.

In this blog, we:

• review the four patents being asserted by VirnetX and why they were granted,
• look for potentially relevant prior art missed to date by the USPTO, and show the connection between these patents and patents owned by Apple, Microsoft, Cisco and others,
• Compare the relative dominance of the leading VirnetX patent to the closest found prior art.

About VirnetX and its patents

VirnetX is a publicly listed technology company whose shares have surged recently on the back of patent assertion wins against both Microsoft, Apple and Siemens. No doubt due to these victories, the share price of VirnetX has risen tenfold since January 2010.

VirnetX claim to have 46 patents and over 100 pending applications. However for the purpose of this blog, we will concentrate on the four patents and their claims successfully asserted against Apple, as recently affirmed by the Eastern District of Texas.

1) US6502135 ('135) was filed in 2000, and claims priority back to 1998. Claims 1, 3, 7, 8 were held to be asserted by the judgement in the Apple case. This patent has 33 backward citations according to Espacenet, 165 forward citations, and an AmberScore (our normalised measure of patent dominance) value of 12.

1. A method of transparently creating a virtual private network (VPN) between a client computer and a target computer, comprising the steps of:

(1) generating from the client computer a Domain Name Service (DNS) request that requests an IP address corresponding to a domain name associated with the target computer;

(2) determining whether the DNS request transmitted in step (1) is requesting access to a secure web site; and

(3) in response to determining that the DNS request in step (2) is requesting access to a secure target web site, automatically initiating the VPN between the client computer and the target computer.

In other words, a client computer (for example your smartphone) requests from a domain name server an IP address associated with a second computer, for example your friend's smartphone. If this IP address is for a secure website, a 'virtual private network' is established.

As a matter of interest, a virtual private network, according to Wikipedia, means:

A virtual private network (VPN) extends a private network and the resources contained in the network across public networks like the internet. It enables a host computer to send and receive data across shared or public networks as if it were a private network with all the functionality, security and management policies of the private network. This is done by establishing a virtual point-to-point connection through the use of dedicated connections, encryption, or a combination of the two.

And why was the patent granted? The applicant argued in a submission to the USPTO dated 13 June 2002 that this patent was inventive over the prior art raised by examiner, 'Boden' (US6330562) in view of 'Risley' (US6332158):

does not disclose establishing a VPN (virtual private network) based on a DNS request for a IP address.

And this argument appeared to have been persuasive.

2) US7418504 was filed in 2003. Claims 1, 2, 5, 16, 21 and 27 were held to be asserted. This patent has 102 backward citations, 26 forward citations and an AmberScore value of 5.2. Claim 1 appears to be similar to claim one of the '135 patent:

A system for providing a domain name service for establishing a secure communication link, the system comprising: a domain name service system configured to be connected to a communication network, to store a plurality of domain names and corresponding network addresses, to receive a query for a network address, and to comprise an indication that the domain name service system supports establishing a secure communication link.

Again this appears to be similar to the '135 patent.

3) US7490151 was filed in 2002. Claims 1 and 13 held to be asserted. Has 116 backward citations and 9 forward citations, and an AmberScore value of 5.0. Claim 1 reads:

1. A data processing device, comprising memory storing a domain name server (DNS) proxy module that intercepts DNS requests sent by a client and, for each intercepted DNS request, performs the steps of:

(i) determining whether the intercepted DNS request corresponds to a secure server;

(ii) when the intercepted DNS request does not correspond to a secure server, forwarding the DNS request to a DNS function that returns an IP address of a nonsecure computer, and

(iii) when the intercepted DNS request corresponds to a secure server, automatically initiating an encrypted channel between the client and the secure server.

4) US7921211 was filed in 2007. Claims 36, 37, 47, 51 held to be asserted. This patent has 71 backward citations and 4 forward citations, and an AmberScore value of 1.1. Claim 36 reads

36: A non-transitory machine-readable medium comprising instructions executable in a domain name service system, the instructions comprising code for:

• connecting the domain name service system to a communication network;
• storing a plurality of domain names and corresponding network addresses;
• receiving a query for a network address;
• and indicating in response to the query whether the domain name service system supports establishing a secure communication link.

These patents were acquired by VirnetX by Science Applications International Corporation (SAIC) in an arrangement that allows for the additional payment of revenue back to SAIC.

About the affirmed Apple judgement

The judgement describes why the court thought that Apple infringed these four patents, and interested readers can read these reasons in the judgement. However, as network patent analysts, we were more interested in the reasons why the judge found the patent to be valid.

In their arguments against validity, Apple referred to a 1996 Publication by Takahiro Kiuchi, which they claimed to anticipate every claim of the asserted patents. The judge came to the view that this reference was not enabling, i.e. not allowing 'one of ordinary skill in the art to make the invention without undue experimentation'.

This Kiruchi reference appears to be C-HTTP-the development of a secure, closed HTTP-based network on the Internet, which refers to a system for communicating between closed groups of institutions of the internet. Of note, this reference refers to closed network rather the internet network discussed by the VirnetX patents.

What potential prior art can AmberScope identify?

This analysis has shown the arguments against the validity of this patent to date have been based on:

• Boden, (US6330562) in view of Risley (US6332158). Boden discloses a Virtual Private Network, but not linking this to a DNS address for an IP address. Risley discloses a domain name lookup system, but does not refer to this to set up a VPN.
• Kiruchi's article on ;">C-HTTP-the development of a secure, closed HTTP-based network on the Internet, which refers to a system for communicating between closed groups of institutions of the internet.

One can presume that the lawyers for Apple et al would have done a thorough job of looking for prior art going into litigation, and the absence of knock-out prior art during litigation suggested that none may exist, or if it does exist, is very hard to find. Regardless, we were curious to see what additional light AmberScope could add to this analysis.

The easiest means of looking for prior art when using AmberScope is to start with the patent(s) being litigated. In this case, unlike many other case studies we have published, searching for prior art from the litigated patent was not successful - but remember that this patent has defeated the best of Apple's and Microsoft's lawyers.

So we tried some other options. We started AmberScope searches based on the patents discussed by the examiner for the '135 patent, namely Boden (US6330562) and Risley (US6332158). We also found an Apple patent that referred to video telephony, and performed a search from there. Again, no strong prior art was found.

The next option was one recommended in a previous blog, namely to use AmberScope to explore the connections to patents identified in a more traditional keyword search using the PatentLens patent search engine, using the following search query:

(("domain name server" or DNS) in fulltext) AND (("virtual private network" or VPN) in fulltext)

The results were then ordered by their date of publication. #6 on the list was WO19980230808 Communication systems architecture to MCI Communications (now owned by Verizon) and which has a priority date of 1996. This patent also has the family members US5867494, US5867495 and and US6690654 (and the earliest publication date for the family being June 1998, for the Australian family member AU199856867)

And in fact, this patent discloses many elements of the VirnetX patents:

• Establishment of virtual private networks (column 101 of US5867495)
• Identification of IP addresses from a domain name service (column 195)
• Encrypted communications (column 82).

So this patent by itself is helpful. But the patent becomes even more helpful if used as the basis for an AmberScope search, as one of the 'ghost patents' (highly ranked but not directly connected patents) found is US5999525 (1996) for a "Method for video telephony over a hybrid network".

US5999525 ('525) also has disclosures of possible relevance to the VirnetX patents, including

The user......connects the computer to an Internet Protocol (IP) network..starts an IP telephony software protocol system....The message contains IP address identifying the connection...computer or virtual private network (column 105) and "The domain name server will distribute calls amongst several locations via a lookup table (column 258)

So between these two MCI patents, we have may have discovered some prior art, providing of course that the filing and publication dates meet the applicable US laws on what constitutes a prior art document. The MCI patents could also potentially lead to other prior art filed or published by the same company or inventors.

Citation connections to Microsoft, Citrix and Cisco patents

Despite the apparent similarity between the VirnetX and MCI patents, and the alleged similarity to Apple's Facetime product, there are few citation connections between these patents.

For example:

• The leading VirnetX patent, US6502135, has no citation connections to either MCI or Apple patents (or even Siemens patents).
• The possibly most relevant MCI patent, US5999525, has no citation linkages to either a Virnetx or a SAIC patent. There was one citation connection however to an Apple patent, being US5561670 for a Method and apparatus for operating a multicast system on an unreliable network - which is more focused on compensating for the effects of signal quality than creating a virtual private network.

Connections to Microsoft, Citrix and Cisco patents.

While there were no citation connections to Apple patents from the VirnetX '135 patent, there were however connections to patent filed by Microsoft, IBM, Citrix and Cisco

In this diagram:

• Red patents are filed or owned by VirnetX
• Green patents are filed by Microsoft - and appear to form into a cluster, unlike the majority of patents filed by the following three companies.
• Blue patents by IBM
• Purple patents by Cisco
• Orange patents by Citrix

Of note, the leading patent in the Microsoft cluster is US7054774 (filed 2003, AmberScore value 6.8), for Midstream determination of varying bandwidth availability, which as suggested by the title is concerned with bandwidth management.

The other applicants were not nearly as clustered. Of note, their leading patents were

• IBM - US5805801 (1997, Amberscore 9.7) is for System and method for detecting and preventing security, and specifically is concerned with blocking known suspect addresses from campus networks
• Cisco - US6243749 (1998, AmberScore 7.0) Dynamic network address updating, and is concerned with updating domain name services
• Citrix - US7706266 (2007, AmberScore 1.3) Systems and methods of providing proxy-based quality of service,and which is also concerned with bandwidth management.

None of these patents appear to be directly related to virtual private networks.

Conclusions of citation analysis

Citation connections are sometimes used to identify or predict patent infringement, and with some success. In this particular case, there were no identified citation connections between VirnetX patents and relevant patents belonging to any of the companies they have successfully sued. Instead there appeared to be two completely separate networks of patents, being the two separate AmberScope networks shown above.

This could be for one of four most likely reasons:

• The allegedly infringing companies were infringing on the VirnetX patent, but had not filed any patents covering the technology they were infringing with
• None of the patent examiners for later patents filed to cover this technology by Apple in this area had noticed any similarities between the later patents and the VirnetX patents. This is possible, but unlikely if such Apple filings exist.
• Despite being a generally accepted tool, citation analysis simply failed in this case. Patent lawyers are often quick to point out that at the end of the day it is the patent claims that ultimately matters, and of course they are right. The role of citation analysis instead is to identify patents that appear to be dominant in their space - and therefore may contain claims that read onto valuable technologies in their space,
• The alleged infringers may have been correct in their post trial assertions that the VirnetX patents were either invalid or not infringed. It should be noted that the infringements were litigated in the Eastern District of Texas, which has a reputation for being friendly towards patent owners.

At this point in time, it is not clear which of these explanation are the most likely.

Relative dominance of the patents in the centre of the two networks

Another way of characterising the two networks discussed above to look at the relative dominance of the patents of the two patents we are comparing, namely the '135 VirnetX patent and the '525 MCI patent. Each sits in the centre of the network - it is worthwhile considering how these two patents compare to those patents directly. In particular we can ask for each patent

• What is its AmberScore value?
• How does this AmberScore value compared to the patents it is directly connected to, both forward and backward connections?

The results of this analysis are shown in the two tables below. The first table lists the patents directly connected to the '135 Virnetx patent, and with higher AmberScore values. The VirnetX patent has an AmberScore value of 12.3, which was enough to put it into 9th position in this list (and which is about 8 times greater than the median AmberScore of 1.6 for all patents directly connected to this patent).

The same table for the MCI patent is shown below. The MCI patent has an AmberScore value of 21.8, which was enough to put it into 3rd position in this list (and which is about 14 times greater than the median AmberScore of 1.5 for all patents directly connected to this patent).

Another means of comparing these patents is to consider the forward citation age profiles, as shown below.

These two tables and this figure help to put the leading VirnetX patent into perspective. It has some relative dominance, but are far from the most dominant patent in its local network.

Conclusions

This review has considered a half billion dollar (and counting) quartet of patent owned by VirnetX, and successfully asserted against Siemens, Apple and Microsoft for their video telephony applications. It shows:

• The asserted claims for the four patents all claim a similar invention
• The listed prior art for this patent does not appear to take into account a series of patents filed by MCI Communications for video telephony, where these patents disclose similar features to that disclosed by the VirnetX patents
• There are no citation linkages between the VirnetX patents and any patents filed by Apple, or MCI
• There is however a series of citation linkages between the VirnetX patents and patents filed by Microsoft, IBM, Cisco and Citrix.
• The leading VirnetX patent, US6502135, sits in 9th position in its network and has an AmberScore value 8 times the median value for all of its connected patents. This contrasts with the closest prior art patent found, US59999525, which sits in 3 place in a list of connected patents, and has an AmberScore of about 14 times the median for this network.

One of the challenges in searching patents and patent landscapes is working with crowded patent landscapes, or patents with lots of citation connections. 

For example, consider patent US4799156 (1986), filed by Strategic Processing, and covering an Interactive market management system:

A system for interactive on-line electronic communications and processing of business transactions between a plurality of different types of independent users including at least a plurality of sellers, and a plurality of buyers, as well as financial institutions, and freight service providers. Each user can communicate with the system from remote terminals adapted to access communication links and the system may include remote terminals adapted for storage of a remote data base. The system includes a data base which contains user information. The data base is accessed via a validation procedure to permit business transactions in an interactive on-line mode between users during interactive business transaction sessions wherein one party to the transaction is specifically selected by the other party. The system permits concurrent interactive business transaction sessions between different users.

This appears to be an early patent for e-commerce, for example describing how Ebay appears to work. Espacenet lists 1417 forward citations  and 10 backward citations, while the USPTO lists 1390 forward citations:

Our AmberScore value, which measures the overall connectiveness of the patent, is 137, or 137 times as connected as the average granted US patent. This was enough to earn it a place in our recent top 10 patents of the 1980s blog. This patent appears to be one of the key early patents for e-commerce, and so a review of its forward citations should provide a good understanding of developments in e-commerce.

However, from a practical viewpoint, this does raise a couple of important questions:

• How can you practically review a list of 1400 odd forward citations?
• In particular, which of these 1400 connected patents are most likely to be most worth looking at?

Readers of this blog should be familiar with AmberScope, which is a way of visualising the citation network around a patent via an intuitive interactive graphical display. However up into very recently, AmberScope too would have struggled with such a highly connected patent network, and would have ended up showing more information that could be usefully ascertained. This would also have slowed down the display of the network, and some computers might have struggled to display such a complex network.

But not any more. A very recent improvement to AmberScope has changed that the way that 'complex' (more than 100 connected and ghost patents) patent maps are shown.

By 'top patents', we refer to the highest ranked patents according to AmberScore, which is the algorithm we have developed to measure the network influence of a patent. We believe that patents with higher value of AmberScore are more likely to disclose important inventions. This is why the our filtering mechanism focuses on the top ranked patents. Similarly, other highly ranked patents are likely to be connected to these highly ranked patents. 

You will note that there are 100 patents shown (see the red circle) - and AmberScope has done this by automatically selecting a value for the % filter that leads to 100 patents - see the red arrow pointing to the % filter.

AmberScope automatically selects this % range to show the top 100 patents. And if you may want to look at more than the top ranked patents, you can simply adjust this % filter to any other values, as in the figure below where by moving the % filter so that the top 200 or so patents are displayed.

Alternatively you can choose to filter by filing year range - the figure below shows the top 53 patents in the 10 years after this patent was filed.

Returning to the top 100 odd connected patent, all years, there is an easy of reviewing these, namely using the 'Next' button found in the bottle left hand corner of AmberScope

This automatically selects the highest ranked patent in the displayed network that has not yet been read. This happens to be US4674044 to Merrill Lynch (AmberScore value of 113) for an Automated Securities Trading System.

When you look at this summary box, you will note a sub-box reading '484 more':

What this label refers to is that there are 484 further patents connected to this Merrill Lynch patent that are not in the network connected to US4799156  - providing a link to further patents in this area.

And we could keep going. The next highest ranked patent is US4903201 to World Energy Exchange Corporation, for an Automated futures trading exchange. This has an AmberScore value of 110, and is a 'ghost patent', i.e was not directly cited by the examiner for the '156 patent, but is still likely be to relevant (note that the yellow patent highlighted below is slightly transparent in nature, showing it is a ghost patent). Ghost patents are of particular value to people aiming to invalidate a patent, but given that the '156 patent is now expired, this may not be an issue.

Of course this is all a little backward looking. What if we wanted to look at more recent patents, say filing in the most recent decade? In the image below, we have set the filing date filter to be between 2000 and 2010, and adjusted the % filter to show the top 50 patents in this age range. Ebay is an obvious contender is this area, and so we have entered ebay in the word highlighter box (which highlights all patents with this term in the title, owner or user comment box). Among the Ebay patents meeting this criteria (with green circles around them) is US7593866. 

Makes searching a crowded patent landscape very easy, doesn't it? And has avoided all of the potential risks of otherwise filtering these patents using filters based on keywords and patent codes.

Test out the new 'auto-filter' to search crowded patent landscapes at AmberScope.com, and make the most of the free beta trial while it still lasts.

Do you need to search every patent in a patent network?

While in same cases you should, you do not need to in all cases. Instead my experience is that simply reviewing the highest ranked patents using the Next button may find you what you are looking for.

As an analogy, consider a Google search, for say hybrid cars. You might run this search in Google:

But you do need to search through all 113 million results? No, of course not. Instead you will likely search the first page or two of results, and find probably find a page that gives you what you wanted when you started the search.

Using the Next button to search results when using AmberScope is similar to this, i.e. you may not need to search for every patent. 

Unless of course you are doing a freedom to operate search - but Ambercite products are not recommended for freedom to operate searches in any case, unless being to complement more traditional patent searching processes.

 * Currently AmberScope is not listing very recent forward citations as our data is about 14 months out of date. We are working on making our data completely up to date, and so this anomaly is only temporary. 

Patent searching is one of the most common activities of many of us in the patent profession, whether we are patent managers, examiners, attorneys, analysts, owners or searchers. Ye patent searching as it stands can be is imperfect, with data suggesting that the majority of granted patent are invalid - even after patent validity searches performed by presumably competent examiners and applicants using high quality databases. This in turn has led to the growth of the non-examiner patent searching community, as represented by the likes of Article One and Patexia.

One possible reason why patent searching can be imperfect is that there there are big limitations when using keywords and patent codes when searching for patents.

Limitations with searching with keywords

Whether intentional or not, different patent applicants (and their patent attorneys) can use different keywords for the same technical concepts. As but one example, a cardboard box can be also be described as a container, carrier, carton, receptacle, package, packaging, and there are probably terms that I have missed. This can be repeated for almost every technical concept, and means that even the most diligent of searchers can miss relevant patents that use different keywords, even allowing for the dictionaries of synonyms now available in some search engines.

Limitations with patent codes

The same applies to patent classification codes such as IPC or USPTO classifications. Because there is always a degree of subjectivity in the allocation of these codes by patent examiners, different patent examiners (for examples in different patent offices) can allocate different IPC codes to very similar inventions. Further errors can result when patent codes are automatically converted from say the USPTO patent classification system to the IPC system.

A further weakness with both keywords and patent codes is that they may not be specific. If we return to patents for cardboard boxes, imagine doing a novelty search for the box similar to that shown here (which is disclosed in US patent 7000824):

Besides the previously referred to problems with the differing keywords, imagine the issues trying to use the possible keywords and narrow down the search, for example as a novelty search. As just one example of a possible search, consider the query shown below, which produces 2040 hits when using the Espacenet search engine.

Maybe we could use a patent code search instead? The European Patent Office has recently partnered with the USPTO to introduce their Cooperate Patent Code  (CPC) scheme, which has a very comprehensive classification scheme. Among these codes is B65D2571/00561, which is listed as a relevant patent code when US7000824 was looked up within Espacenet.

This code sounds reasonably relevant, so if we use this code as part of an Espacenet patent search, we end up with 339 hits, as shown below.

But of course, there is no guarantee that all relevant patents fall within this patent code.

And in fact there is a second limitation. A given invention, even as apparently simple as the box shown above, can cover several different concepts. For example, this box is a:

• rectangular carton
• cardboard carton
• easy open carton
• shelf ready carton (suitable for being displayed on retail shelves).

All at the same time. None of these descriptions is 'wrong' - and each are different concepts. Ideally, each description should have its own patent code, and indeed many patents have a variety of patent codes to cover these different concepts. But what a given examiner identifies the carton by one concept and patent code - and a second examiner for a very similar invention instead focuses on a second concept and hence patent code? The patent codes would differ - even if both patent codes are right.

But what if we instead do a novelty search based on citation connections to this patent using our new patent search engine AmberScope? AmberScope has been described here, case studies are found here, and a video introduction is found here. In short, a patent number is entered into a search box, and connected patents are shown as below:

The image shows all of patent connected to US7000824  via citation connections. These patents in turn connect to other patents. And patents can easily reviewed by hovering your mouse over a patent, or using the "Next" button (lower left corner) to systematically review each in order. For example, one of the first patents that comes up with when using the Next button is US4417661, which appears to be similar in some ways.

This all starts to become a lot easier doesn't it? 

This search is also shown in the YouTube video found here.

More to the point, some of the results you will end up finding could have very different keywords and IPC codes. For the example, the US4417761 patent found above has the following patent codes

Which is different to the CPC patent codes we looked at above. And even the technical keywords differ, as shown in its abstract:

A carton, formed of a unitary blank of paper board, having an openable pull flap which can be reclosed by the interlocking of a pull tab and a slot receiving an enlarged end of the tab. The flap is located on only one panel forming the carton or on two such panels. The tab is located either inside or outside the flap, and the slot is correspondingly located either outside or inside the flap.

And this is far from unusual. For example, consider:

• A previously published case study showing non-overlapping patent codes and keywords for patents connected to a 'Google glasses' patent.

• A previously published case study showing the range of non-overlapping patent codes and keywords for patents connected to an Apple touchscreen patent.

• In another published case study, a potential prior art patent being asserted against Microsoft for the 'tiles' they use in their Windows 8 operating system did not use the word 'tiles' but instead used the term software 'containers' to describe this concept (and I thought a container was another word for a cardboard box!)

• Or in an unpublished (because it was a commercial client) case study, a highly relevant but missed by the USPTO prior art for a patent (where carbon dioxide was a critical part of the claims) did not use the words 'carbon dioxide' at all in the patent - but instead using the term 'carbonic acid gas' - which is another word for carbon dioxide.

Can your business or firm afford to miss relevant patents that may use the 'wrong' keywords or patent codes?

If not, we suggest that you start including AmberScope as part of your patent searching process today:

1. Use your existing patent search engines to identify similar prior art (or you may already know some starting patents, such as patents you are trying to invalidate)
2. Use the patents as focus patents in AmberScope searches - explore connected patents to identify patents that may be missed by keyword or patent code searching 

Postscript - why can't patent codes be used to search within AmberScope?

A few users of AmberScope have asked why we can't apply keyword or patent code filters within AmberScope?

To understand this question better, it can help to take one step back from the process and ask 'why do use keywords and patent codes at all?'

The answer, rather self evidently, is that we do this because there are about 90 million published patents, and searching through each of these patents for a specific patent or group of patents would be impossible. So we apply keywords and patent codes as filters, to reduce the number of patents you need to manually review to a manageable number. When are you applying these filters, you are asking the question 'show me the patents that have these keywords and/or patent codes'.

When are you using AmberScope to do citation searching, you are applying a third type of filter to ask a different question: 'show me the patents directly and indirectly connected to my focus (starting) patent'.

We have found from deep experience that these patents, i.e. the patents connected to our focus patents, can be highly relevant to your original query and yet still have very different keywords and IPC codes, as discussed above. And this is why we don't think that applying a keyword or patent code filter would be helpful to our users, because there is a large risk that you might filter out relevant and not previously known results.

More to the point, you would possibly end with a similar set of results to what you would have ended up with if you were just using keyword and patent code filtering by itself - and what is the value of that? You might as well just use a conventional patent searching in that case (and then miss out of the additional information available from AmberScope).

Last week's blog on the most influential patents in the 1980s was very well received by readers, and we thank you for the positive feedback.

But what were the dominant(most influential) patents of the 1990s? Which you will recall was the decade that saw the invention of the worldwide web, pentium processor, first HIV treatment and Java computer script.

Like last weeks list, this list of the dominant patents of the 1990s has been compiled using our AmberScore patent scoring system, which assesses patents based on their position within the patent network. AmberScore values can be quickly and assessed for individual patents in our AmberScope patent search system. Bulk AmberScore data for the likes of portfolio analysis can be obtained by contacting Ambercite. 

1) Leading this list was US5143854 Large scale photolithographic solid phase synthesis of polypeptides and receptor binding screening thereof, filed by Affymax of Palo Alto in 1990. According to Espacenet, US5143854 has 55 backward citations and 1384 forward citations, and we calculated that AmberScore value of 151 (or 151 times the influence of the average granted US patent less than 20 years old). 

This fascinating technology is for screening biological agents such as antibodies and cells so that biochemists can identify them.

The process begins with attaching one end of specific molecules to a substrate. At the other end of these molecules are 'photo-removable' groups. Light is selectively focused onto these 'photo-removable groups', which removes them. A monomer can be washed over the substrate which then joints to the molecule, creating an engineered polymer. This molecule can also include a photo-removable group, allowing the process to be repeated with a second monomer, and so on. Different locations of the substrate can be built up with different polymers in a matrix type arrangement.

Once the substrate can be manufactured with the engineered polymers (and a range of engineered polymers can be added at a matrix of different locations), the substrate can be use to screen different biological agents such as anti-bodies cells etc, which adhere to the different locations of the substrates depending on their exact chemical compositions. In this way, the agents can be analysed and screened. 

Affymax appear to be using this technology as part of a discovery platform based on advanced recombinant peptide and peptide chemistry techniques that has been used to generate novel peptide alternatives to protein drugs

2) In second place is US5643826 (1994) Method for manufacturing a semiconductor device, filed by Semiconductor Energy Laboratory (SEL) of Japan. US5643826 has 15 backward citations, 1100 forward citations and an AmberScore value of 142.

This patent covers A process for fabricating a highly stable and reliable semiconductor, comprising: coating the surface of an amorphous silicon film with a solution containing a catalyst element capable of accelerating the crystallization of the amorphous silicon film, and heat treating the amorphous silicon film thereafter to crystallize the film.

In practice, this is done by adding very small amounts (less than 200 ppm) of a metal such as nickel into the solution to promote the crystallization.

As a matter of interest , SEL is majority owned by Shunpei Yamazaki.

Mr Yamazaki has been previously mentioned in the pages of this blog, being the second leading global inventor in terms of patents filed with over 11,000 patents listed in Espacenet (only beaten by an Australian), even if he is not listed as an inventor on this patent. SEL is also of note being a company founded back in 1980 purely to develop and licence IP (as opposed to manufacturing), and so being a lot earlier into this field than many companies who have adopted a similar corporate strategy such as Intellectual Ventures. 

3) In third place is a very different invention, being US5111638 Method for wrapping an object with a material having pressure sensitive adhesive thereon, filed by Highland Supply Corporation in 1991. US5111638 has 42 backward citations, a 'mere' 452 forward citations, and an AmberScore value of 136.  

In simple terms, this patent covers wrapping the likes of a flowers in a pot with a sheet covered or partially covered with pressure sensitive adhesive, and where the sheet adheres to either the pot, or the material that it overlaps.

On first impression, this seems an unlikely candidate for a top 10 patents of the 1990s list, even if the claims are quite broad. But there are good reasons for this inclusion.

This patent was invented by Donald Weder, who also made the list of leading patent filers blog, in 7th place (and in fact the USPTO have placed Weber as the US's leading inventor by combining his design and standard patents, ahead of Thomas Edison, whilst our top filers blog only referred to standard patents). Weber's family company Highland Supply Corporation of Illinois claims to supply over 12,000 products to the floricultural industry, and to be the world's leading supplier of floral packaging solutions.

An analysis of the forward cites to this patent, as well as an AmberScope analysis, has confirmed that this patent sits near a centre of a large and tight cluster of related patents, the vast majority also invented by Weder. Being at the centre of a large and tight cluster will boost the AmberScore value of a patent compared to patents with the same number of forward citations, but where these citations are not connected to each other. This explains the high AmberScore value for a comparatively low number of forward citations.

4) Continuing the no doubt very surprising floral theme is the 4th ranked patent US5523520 Mutant dwarfism gene of petunia, filed by Goldsmith Seeds Inc. in 1994, and now owned by Sygenta. US5523520 has just 3 backward citations, 1787 forward citations and an AmberScore value of 131. 

Why would dwarf petunias have attracted so much attention? Sygenta claims to be one of the largest wholesale breeders of hybrid flowers in the world. But the real reason may be that it was one of the first genetically engineered commercial plants, hence just the 3 backward patent citations compared to its 1787 forward citations. A review of the forward citations showed that the company with the most forward citations is Monsanto, with over 800 forward citations from patents covering genetically engineered variants of a broad variety of plants, ranging from soya beans to cotton.

5) Electrical engineers will no doubt be pleased that the reminder of the patents in this list are all concerned with ICT. In 5th position is US5172338 Multi-state EEprom read and write circuits and techniques to Sundisk Corporation of California (1990). This patent has 9 backward citations, 1049 forward citations and an AmberScore value of 120.

Electrical engineers would also recognise that an 'EEPROM refers to a predecessor of the solid state memory that stores data in modern smartphones and tablets, as well as USB memory sticks. The improvement claimed in this patent is the ability to store information in each memory cell in more than one 'state' of information (voltage level), so improving the amount of data that could be stored.

6) In 6th position is US5177567  Thin-film structure for chalcogenide electrical switching devices and process therefor, filed by Energy Conversion Devices in July 1991, and now owned by Ovonyx of Michigan. US5177567 has 6 backward citations, 513 forward citations and an AmberScore value of 115. 

This patent claims an improved structure of an alternative type of solid state memory based upon the alternating physical state of chalcogenides (a type of chemical compound). These types of flash memory are known as phase change memory, in which the chalcogenides can be either set to be in an amorphous (non-crystalline) state with high electrical resistance, or in a crystalline state with low electrical resistance. Hence data can be stored via its state of electrical resistance. The claims of this patent are focused on the structure of the cell, in particular the layout of the insulation material shown in positions 2 and 6 in the figure below, which surround the central body ofchalcogenide shown in position 3.

Ovonyx was founded in 1999 to commercialise phase change flash memory as originally invented by Stanley Ovshinsky of Energy Conversion Devices, who are thought to be the world's largest manufacturers of flexible solar cells. Phase Change memory is attractive to the ICT industry because it promise the potential of very fast programming time, although its temperature sensitivity is a known drawback.

7) Another EEPROM patent is in 7th place, namely US6011725  Two bit non-volatile electrically erasable and programmable semiconductor memory cell utilizing asymmetrical charge trapping,  filed by Saifun Semiconductors (now Spansion) in 1999. US6011725 has 45 backward citations, 956 forward citations, an AmberScore value of 111, and claims an innovative structure for an EEPROM that speeds up the rate that it can be read and erased. 

8) In lucky number 8th position is US5848932  Method of playing game and gaming games with an additional payout indicator, filed by Anchor Gaming in 1997 and now owed by IGT. US5848932 has 18 backward citations, 724 forward citations, and an AmberScore value of 110. This invention covers a slot machine with an additional payout indicator controlled by mechanical means, such as the dial shown at the top of the slot machine below. Bonus payouts are now a very common feature of such slot machines, providing an additional incentive for punters to keep playing.

9) In 9th position is US5661506 Pen and paper information recording system using an imaging pen , filed by SIA Technology in 1994. US5661506 has 34 backward citations, 1231 forward citations, and an AmberScore value of 109.

This invention covers a system for writing on a piece of paper covered with a pre-recorded pattern of pixels, invisible from the naked eye. A small camera on a pen records the position of the pen via these 'invisible' markings and passes this position back to a computer which is able to record the markings being made on the paper.

This is a predecessor  of the so-called smart pen which is commonly used by graphic designers and other users of computers. One example of this is the LiveScribe pen, which in turn is based on Anoto intellectual property, which appears to be very similar to the SIA invention. The most cited patent in the Anoto patent portfolio is US5852434, which has an AmberScore of 95, enough for it to appear in 18th position on this same list (and a second Anoto patent appears in 21st position).

10) And completing the list of top 10 patents is another patents from Energy Conversion Devices (now owned by Ovonyx), namely US5166758 Electrically erasable phase change memory which was filed in January 1991. US5166758 has 6 backward citations, 536 forward citations and an AmberScore value of 108. This claims a different aspect of the concept discussed in the later filed #6 ranked patent, namely the broad concept of using change in cell electrical resistance to store data in solid state memory, as opposed to changes in cell voltage as discussed by the #5 ranked patent in our list.

And positions 11 to 20?  These include patents for surgical implants, e-commerce, wireless data transfer, semiconductors, smartphone and more patents for solid state memory. 

Discussion - the value of AmberScore.

This review of the most domianant of the 1990s has perhaps produced a few surprises. Some of the inventions should not surprise, such as inventions in the areas of improved medical diagnostics, solid state memory (essential for the battery life achievable in modern smartphones and tablet computers), genetically engineered plants, and gaming machines which have become ubiquitous in many countries. Other patents in this list might surprise, such an invention for floral wrap.

So what does this tell you about the value of AmberScore? AmberScore is a guide to highly connected patents. Highly connected patents indicate areas of high patent density, which in turn should suggest areas of high commercial potential, as applicants will typically only file patents in areas that they think could make them money. As with other 'predictions' of the future, the potential may not work out, or take longer than expected to bear fruit. An analogy can be drawn with the crowd favourite at horse races or indeed any other expression of the wisdom of crowds - while not a guarantee of success, such favourites are well worth looking at.

In some cases, the potential may have been realised by other companies. For example the dwarf petunia patent by itself may not have created a lot of value, but was the forerunner of Monsanto's significant business with genetically engineered plants such as roundup ready soybean. Similarly while we have no direct evidence that the SIA patent has been commercialised, the very similar patent filed by Anoto has been commercialised by LiveScribe and possibly other companies.

In other cases, the IP may have been licensed out to other companies, such as the Semiconductor Energy Laboratory patent for an improved semi-conductor, or may yet to be successfully commercialised despite clear potential, such as the inventions for a phase change memory.

Another observation is that these patents all have a small number of backward citations compared to a very large number of forward citations, suggesting that they were ground-breaking patents in their field.

And this shows the value of AmberScore. It is not designed to replace the normal commercial and legal evaluation of the value of a technology or a patent. But it does suggest where to start looking for such value, which can be very helpful when faced with a large portfolio of patents to consider, and without the time and resources to look individually at all of these patents.