Pay Attention to Detail in Drafting Patent Applications

Zipher and Markem have been in a longrunning dispute over tape drive systems used in industrial thermal transfer printers for printing ‘best before’ dates or batch codes. Certain employees of Markem left to set up Zipher and then filed a number of patent applications. As a result of an earlier court case, it was held that Markem was entitled to some of the broader claims of the resultant patents, but certain narrower claims belonged to Zipher. Zipher subsequently sued Markem for infringement of those narrower claims. The main interest from the latest round in Zipher v. Markem ([2009] FSR 1) is Markem’s defense of insufficiency of disclosure, and in particular:

(a) whether several independent minor defects in a disclosure might in combination present the skilled reader with an undue burden; (b) whether a brief mention of an alternative embodiment might detract from the sufficiency of a disclosure.

The case also addresses an important point of procedure (see box), viz. whether the Court has discretion to refuse to enter an amendment to a patent.

The patents concerned the regulation of tension in the thermal transfer ribbon used in the printers. The tension was regulated by measuring the currents that were supplied to two motors driving two spools on which the ribbon was mounted, and then controlling the motors to keep the tension within limits. If the motors were DC motors, it might have been a simple matter to measure the torque by measuring the current. But they were stepper motors driven by pulse width modulation drivers, so the question arose as to whether there was adequate description of how to separate the workrelated element of the current from the total current to the motors.

The description taught little more than that the current to the motor should be sampled, filtered and averaged to measure the current and hence the torque.

There was a description of the sampling. Zipher’s expert, a Senior Lecturer of Electrical Engineering from Cambridge University, gave evidence that the description of sampling was quite adequate, but in his evidence he used a sampling rate far in excess of that described in the patents. Markem’s expert, an electrical engineer with no experience in thermal transfer printers, concluded that the description would typically give just seven samples, and that this would not be enough. Zipher’s expert said it was the DC element of the current that was of interest, obtained by the step of averaging. Markem’s expert said it must be some undescribed AC component that is of interest, obtained by the step of filtering.

On balance, the judge (Mr. Justice Floyd) preferred the evidence of Markem and held that the patents did not give an adequate description of how to measure the components of the currents which were related to the tension in the ribbon. This defect alone was held to invalidate the patents, but the question was also considered as to whether various other grounds of insufficiency should be considered in turn or whether a combination of defects in the description might together have prevented a skilled team from performing the invention.

Among the problems considered in turn were:

1. an error in the tension measuring formula that failed to take account of the changing spool diameter as the ribbon unwinds;
2. an admission that temperature variations would play a part, but little or no description of how to account for them; and
3. a suggestion to measure current direct to the motors rather than current to the motor drivers, but no additional details. The judge held that the first and second problems would introduce errors that, taken alone would not impose an undue burden on the skilled reader to arrive at a workable prototype, but that the patent “presents the reader with such a combination of defects that it does not serve as a clear or complete description of how to perform the invention”.

Markem’s expert witness explained why in his opinion the combination of defects would lead to difficulty in practice:

My son came to me and just said, ‘I have just changed the spark plug in the lawnmower.’ The next time I go and try and start the lawnmower and it does not start, I would . . . look at the spark plug and the connection to it. If instead my son came to me and said, ‘Actually, dad, I have just taken the entire lawnmower into pieces . . . and put it back together again’ and I then start it and it does not start, I don’t have a clue what he has done wrong, and that is with a machine that you actually knew worked yesterday.

Floyd J accepted that Markem’s proposition applied with particular force in this case. It would take something approaching invention, or at least a research project, to fill the gaps left by the patents’ teaching.

Comment

This ruling emphasizes the importance of careful and thorough patent drafting. Infringers will be looking for defects in the teaching of patent specifications, however minor, with a view to running the argument that in combination they render the specification insufficient.

Take the example of temperature compensation – a factor engineers frequently have to consider, and often one for the lower-level technician to address, for example by running tests and making appropriate compensations. In this case, the patent itself admitted that there would be a temperature-related function, but indicated that this could largely be ignored provided the motors were at approximately the same temperature. Would it have been better for the patent specification to have remained silent on the subject? Surely a teaching that it will work in limited circumstances (when the temperatures are equal) is sufficient?

Or were Floyd J.’s comments merely obiter? After all, one of the insufficiencies alone was fatal, so of course the cumulative effect of them all was fatal.

One can envisage insufficiency defenses becoming prolonged, detailed and expensive if defendants nit-pick every possible defect to run a combination-of-defects defense.

Worse is the notion that throw-away comments that alternative arrangements can also work might give grounds for “classical” insufficiency. These embellishments are often added by inventors and patent attorneys at the last minute, in part to support broad claims that might be susceptible to attack on grounds of Biogen insufficiency1. But Floyd J’s ruling was not that the claims were too broad (he did indeed separately consider no less than seven individual allegations of Biogen insufficiency). Now we have the spectre that such an embellishment can be fatal to the entire case if it is shown not to be workable and the skilled person would not readily see that the suggestion was not one to be pursued.

Heretofore, classical sufficiency has merely required that there is something that is adequately described that falls within the scope of the claims, and Biogen insufficiency has required that the claims are not so broad as to encompass something that owes nothing to the teaching of the patent. Conceivably we now have a third attack, viz. that there is also something that falls within the scope of the claims that is inadequately described. This is what is set out in headnote 39 to [2009] FSR 1. But this is surely too literal a reading of Floyd J.’s judgement? Had the description not had one significant defect in itself fatal, and several other defects which in combination were fatal, it would surely not have mattered that there was a pointer down a blind alley? Zipher have not appealed these aspects of the judgement, so we will be stuck with these questions for some time.

In the meantime, we do not recommend slimming down a description to avoid mention of known but unresolved problems or to avoid throw-away alternative embodiments. Better to anticipate implementation problems and suggest possible solutions or explain why they are not considered significant.

Better still, of course, to flesh out the possible solutions to the problems and to flesh out the alternative embodiments.

1See the Summer 2008 edition of this newsletter for a discussion of Biogen insufficiency. That article is also available at http://www.jenkins.eu/pi-summer-2008/hurrah-for-productclaims. asp.

Court has Limited Scope to Refuse Amendment of Patent

When the EPC 2000 came into force, it introduced the possibility of central amendment of a European patent, without the need to request the EPO to exercise its discretion to allow the amendment. The only procedural restriction is that opposition proceedings are concluded. Accordingly, it would be inconsistent for the UK court to refuse discretion to allow an amendment in circumstances where the amendment can be made centrally.

In Zipher v. Markem , Floyd J. ruled that the UK Court no longer has wide discretion to refuse to enter amendments (whereas formerly discretion could be refused on grounds such as delay or lack of full disclosure or other inequitable conduct). The only applicable factors now are (i) appropriateness of the amendments to the proceedings, (ii) their necessity and (iii) procedural fairness.

It remains the case that where there are pending opposition proceedings before the EPO, there is no unfettered right to have the patent limited. Refusal of an amendment during a pending opposition is justified if it would have no effect on the opposition and could be made later if the patent survives. Nor would it be procedurally unfair to refuse to enter an amendment with the consequence that the patent is revoked in opposition before it is amended in Court. If it were not so, a patentee could derail the Court proceedings by claiming the right to amend at the last moment.