Monday, 17 November 2008
On Friday 14 November, Mr Justice Arnold delivered his judgment in Armour Group Plc v Leisuretech Electronics Pty Ltd  EWHC 2797 (now available from BAILII here). The case related to Leisuretech's European patent EP1004222 (not EP1004221 as stated in the judgment) for a distributed stereo system. Leisuretech claimed that Armour were infringing their patent, and Armour in turn sought revocation of the patent on the ground that the claimed invention was obvious.
The claimed invention covered a distributed stereo audio system in which a particular type of signal cable known as 'Cat5' (no feline connotations) was used for both audio and power connections. In the distributed audio system (as shown in the figure, right), a cable (11) was used to connect both a signal source (5) and power supply (10) to an amplifier (4), different pairs of the cable being used for left and right audio signals and for a DC power supply from the power supply to the amplifier.
Much detail regarding the state of the art at the 1997 priority date of the patent was gone into, helped by expert witnesses from both sides. Through this, it was established that Cat5 cables were fairly commonplace in the field at the time. They were generally used for transmission of audio and control signals, but not usually for supplying DC power, largely due to the resistive losses inherent in such cables.
It was, however, well known that Cat5 cables could carry small amounts of power, and there were certain integrated circuit (IC) amplifiers widely available at the time that would at least work with these power levels. Even though these would not be regarded as 'hi-fi' amplifiers, Arnold J considered that relevant segments of the market did not necessarily require more than "basic hi-fi quality" (an oxymoron?).
Arnold J found that it was obvious to arrive at the invention from any one of three starting points: i) starting with the known amplifiers, Cat5 cables would be an obvious choice to use for supplying power; ii) starting with the cable, IC amplifiers would be an obvious choice given the low power capability; or iii) starting with the known system architecture, an IC amplifier and Cat5 cables would be obvious choices to make. The patent was therefore found to be invalid and ordered to be revoked.
(below: cat 5 is special)
The IPKat notes that this case proved to be quite a test for the Windsurfing/Pozzoli approach on inventive step, which has to be applied quite carefully for alleged inventions having a combination of features that might or might not be arrived at through a combination of apparently obvious steps. He wonders if it might have been more straightforward to use the EPO problem-solution approach instead, which might have made easier work of assessing the different non-inventive steps taken to arrive at the claimed invention by simply seeing each of them as small problems with clearly obvious solutions. Could this have been done, or would it have been sacreligious?