Dyson Technology Ltd v Samsung Gwangju Electronics Co Ltd

For novelty, prior art must disclose subject matter which would necessarily infringe the claim and must disclose it sufficiently to enable the skilled person to perform it. An express disclosure remains relevant even if described as optional.

Obviousness is assessed by identifying the skilled person, the common general knowledge, the inventive concept, the differences from the prior art and whether those differences require invention. Commercial disadvantages do not establish a technical prejudice. A patent need not prove experimentally that an invention works, but its disclosure must make that sufficiently plausible where an established technical prejudice is relied upon.

Added matter is assessed by a strict comparison of the original application and the proposed amendment through the eyes of the skilled person. Subject matter may not be extracted from a specific embodiment and generalised without clear and unambiguous disclosure.

Dyson sought revocation of two Samsung patents concerning multi-cyclone dust separators for vacuum cleaners. Dyson relied on lack of novelty and inventive step over Conrad, Gamou, LG, Sanyo, and the DC07 and DC08 vacuum cleaners. Samsung applied unconditionally to amend both patents, while maintaining that the granted patents were valid.

The principal issues concerned construction of “vacuum cleaner”, “separating dust”, and sequential separation according to particle size; novelty and obviousness; and whether the proposed amendments added matter under section 76(3)(a) of the Patents Act 1977.

1. Construction. “Vacuum cleaner” was construed broadly. It was not confined to domestic or light-industrial machines. “Separating dust” could include concentrating dust in a scavenge airflow and thereby separating it from the cleaned airflow. “For separating” meant suitable for separating. Sequential separation according to size did not require successive stages to be designed with increasing efficiencies.

2. Novelty. Applying Synthon BV v SmithKline Beecham plc and General Tire and Rubber Co v Firestone Tyre & Rubber Co Ltd, Conrad disclosed an optional third cyclonic stage and therefore anticipated claim 1 of ‘603. It did not disclose the particular ducting required by claims 4 and 5. Gamou disclosed the relevant first, second and third cyclone sizes, but its second embodiment sent the cleaned airflow to the atmosphere and passed only the dust-laden scavenge airflow through the third cyclones. Claim 9 of ‘606 was therefore novel over Gamou.

3. Obviousness. The structured approach in Pozzoli v BDMO SA was applied. There was no established technical prejudice against adding a third cyclone stage. The skilled person would appreciate the potential improvement in separation efficiency and would have substantial pressure-drop latitude. Claims 4, 5 and 19 of ‘603 and claims 9 and 14 of ‘606 were obvious over Conrad. Claims 9, 19 and 20 of ‘606 were not obvious over Gamou; claims 1 of ‘603 and 9 and 14 of ‘606 were not obvious over LG; and none of the A-list claims was obvious over Sanyo. All A-list claims were obvious over the DC08.

4. Amendment. Applying Bonzel v Intervention Ltd (No 3) and Vector Corp v Glatt Air Techniques Ltd, the amendments to claim 1 and new claim 4 of ‘603 were not allowable, although new claim 13 was otherwise permissible. For ‘606, amendment of claim 9 and introduction of new claim 21 were allowable, while new claims 14, 19 and 20 added matter and were impermissible.