In the case of Agilent Technologies Deutschland GmbH v Waters Ltd (2005), the claimant, the proprietor of a European patent for a pump and control system, brought proceedings against the defendant for patent infringement. The patent is for a pump for delivering solvent under pressure to high-pressure liquid chromatography columns. In particular, the patent relates to the control of the flow rate of the pump by altering the stroke volume and the frequency of reciprocation of the pistons.

In earlier proceedings, the court had found that an earlier version of the defendant's device (the 'automatic device') infringed the claimant's patent and held the patent valid. The defendant modified its device to create a new device (the 'manual device') which was the subject matter of the patent infringement claim. The pump and control system of the manual device operated in what was referred to as 'manual mode', in which flow rate and stroke length were independently selected by the operator. The result was that the manual device no longer maintained any predetermined relationship between stroke length and flow rate other than that imposed by maximum and minimum possible frequencies and stroke lengths.

The judge held that the defendant's manual device did not infringe the claimant's patent because it was not within the scope of the patent.

The claimant appealed against the decision and contended that the patent covered the defendant's manual device as a matter of plain language as 'Control Means (i) coupled to the drive means; (ii) for adjusting the stroke length of the pistons; (iii) in response to the desired flow rate of the liquid delivered (iv with the stroke volume being decreased when the flow rate is decreased and vice versa; (v) such that pulsations in the flow of liquid delivered to the output of the pumping apparatus are reduced'. The appeal was dismissed and the Court of Appeal held that:

Patent claims were to be construed as if read by the notional skilled man in context; In the instant case, it was the 'control means' which was to adjust the stroke length 'in response to the desired flow rate' not the operator; The operator was not part of the 'control means' of the claim, and the response called for by claim (iii) was not present in the defendant's device; and The judge had been entitled to find that the defendant's device did not infringe, being outside the scope of the patent. If you require further information contact us.

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