Dyson Technologies Limited v Samsung Gwangju Electronics Co Limited (2009)

In this recent decision, Arnold J has helpfully restated the tests for novelty, obviousness and patent amendments.

The subject of the dispute between Dyson and Samsung were two of Samsung’s UK registered patents. The patents described and claimed similar inventions in which the key feature was the use of a series of three cyclones to separate dust from air in a vacuum cleaner. Cyclones are used to separate solids and liquids from gases. In a cyclone, air is caused to spin in a vortex and the particles of dust experience a force directed away from the axis of rotation (centrifugal force) which thus cleans the central layers of air. Although cyclones are already widely used in domestic vacuum cleaners, manufacturers are always attempting to increase their efficiency. It is common for multiple cyclones to be arranged in parallel with each other and for two cyclones to be arranged in series with each other

Dyson had issued revocation proceedings in the High Court against Samsung’s patents which had a priority date of 29 March 2005 on the basis of lack of novelty or lack of inventive step. In support of this argument, Dyson relied on two of its own machines and a Japanese utility model. Samsung applied to amend its patents and Dyson opposed the applications on the basis that the amendments would result in additional matter being disclosed. Dyson also argued that even if Samsung amended the patents, the claims would still be invalid.

The person skilled in the art

In this case, the person skilled in the art was held to be a person involved in the design and development of cyclonic vacuum cleaners, to have a degree (or equivalent) in mechanical engineering, physics or another relevant discipline, a number of years of relevant practical experience and access to computational fluid dynamics software for the purposes of simulating airflow within any particular design.

There was some dispute between the parties as to what constituted the common general knowledge in this case and it was held to include an understanding of cyclone technology in general, the principle designs of cyclone used in domestic vacuum cleaners on the market in March 2005 (and the preceding period) and the types of filters used in domestic cleaners. The task of the Court was to determine what the person skilled in the art would have understood the patentee to have been using the language of the claim to mean. Arnold J held that the term “vacuum cleaner” had a broad meaning and covered apparatus that sucked up dust and dirt from a surface. This interpretation meant that one of the pieces of prior art (which related to an industrial device) was included for consideration.


For a piece of prior art to anticipate a patent that prior art must, 1- disclose subject matter which, if performed, would necessarily infringe that claim: and 2- disclose that subject matter sufficiently to enable the skilled addressee to perform it.

The parties disputed that the first requirement was met. The Court held that one of the claims was anticipated by a piece of prior art which disclosed the option of a plurality of individual cyclones in separate sequence and therefore of three cyclonic separators in series. It did not matter that this was not a preferred option in the prior art. The prior art also disclosed that the three cyclonic dust separation units are “for sequentially separating dust particles…according to their size” and that the third cyclonic dust separation unit “comprises a plurality of cyclone chambers”.


A patent will be invalid for lack of inventive step if the invention claimed in it would have been obvious to a person skilled in the art having regard to the state of the art at the priority date.

Arnold J distilled the claims of the patents down to several inventive concepts to be considered in relation to obviousness. Samsung argued that a skilled person who had the idea of putting three cyclones in series in March 2005 would have considered that the idea was not worth pursuing because of a technical prejudice against increasing the pressure drop over that encountered with two cyclones in series. It was held that the patent literature did not support the existence of such a prejudice. The Court held that three stage cyclones had been done before in industry and in vacuum cleaners and would have been (along with some of the other claims of the Patents) obvious on the basis of one of the Dyson machines and a US patent, referred to as ‘Conrad’.


Samsung had applied to amend the Patents. Dyson argued (relying on section 76(3)(a) of the Patents Act 1977) that no amendments of the Patents should be allowed because they would result in the specifications disclosing additional matter. The Court must ascertain through the eyes of the skilled addressee what is disclosed, both explicitly and implicitly in the application, do the same in respect of the patent (as proposed to be amended) and compare the two disclosures and decide whether any subject matter relevant to the invention has been added whether by deletion or addition. Subject matter will be added unless it is clearly and unambiguously disclosed in the application as filed (both expressly and implicitly). The Court ultimately held that the majority of Samsung’s amendments were not permitted.

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