Pages 128-136

INFORMATION FROM THE CONTRACTING / EXTENSION STATES

GB United Kingdom

Judgement of the Patents Court^*of 3 October 2000 - Dyson Appliances Ltd. v. Hoover Ltd.

Headword: "Vacuum cleaner"

Patents Act 1977, sections 2(1), 3, 72(1)(c), 125

European Patent Convention, Protocol on the Interpretation of Article 69 EPC

Keyword: European patent - Addressee - Nature and degree of qualification to depend on scope and degree of sophistication of subject-matter - Common general knowledge - Negative aspects of knowledge amounting to prejudice - Construction of claim - Meaning and effect of "cleaning" in claim for appliance - Cyclone unit - Tapered "frusto-conical" part - Infringement - Novelty - Whether experiments to repeat prior art proposal adhered to document interpreted as at its date of publication - Inventive step - Whether obvious to take step from prior art if no problem perceived - Sufficiency - Whether patent included other methods of connection within its scope without teaching what those were

Summary

The patent in suit in an infringement action (EP (UK) 0042723) related to a vacuum cleaner in which dirt-laden air from the surface being cleaned passed through a cylindrical cyclone in which coarse debris was deposited and then through a tapered cyclone in which fine dust was deposited. Claim 1 read as follows:

"A vacuum cleaning appliance including cyclone units of successively higher efficiency in the capability of depositing fine dust, in series connection, the highest efficiency cyclone have a frusto-conical part tapered away from its entry and means for generating an airflow from a dirty air inlet sequentially through the cyclone units characterised in that a lower efficiency cyclone unit upstream of the highest efficiency unit has a body without the taper away from the air entry, being either cylindrical or having a reverse taper."

At the priority date, commercially available vacuum cleaners for domestic or industrial use all passed the dirt-laden air through bags which became full of dirt. None of them used cyclonic separation to deposit dirt, although this had been the subject of a paper proposal (referred to as van Berkel) published more than 40 years previously.

The defendant argued that the patent was invalid on the ground of lack of novelty in view of prior art publications which described the use of a sequence of cyclones to remove particles from a stream of air, referred to as Campbell and Johnston/Donaldson respectively, and that it was obvious in view of those citations and van Berkel. In Campbell, where the collected solid was the desired product, it was questionable whether any deposition would have occurred in the non-tapered part of the appliance; the parties carried out experiments purporting to elucidate this. The machine described in Johnston/Donaldson was a mobile mining drill including a sequence of cylindrical and tapered cyclones to remove air-borne particles generated by the drilling. The pressure drops were titanic by domestic and industrial vacuum cleaning standards.

The alleged infringement was a vacuum cleaner comprising three units referred to as SU1, SU2 and SU3 connected in sequence. SU1 was a cylindrical cyclone, in which coarse debris was deposited. All the air from SU1 passed into SU2 where centrifugal action separated and concentrated the flow into two streams without depositing any dirt. One stream, of relatively clean air, exited from SU2 without further treatment. The other stream of relatively dirty air, about one fifth of the volume flow, passed into SU3. This was a tapered cyclone in which a high proportion of the remaining dirt was deposited. The cleaned air from SU3 was exhausted back into SU2. Recirculation from SU2 and SU3 was possible but the extent to which this occurred was questionable.

The defendant argued that SU1 and SU3 were not connected in series as required by the patent because SU2 intervened. It also argued that recirculation between SU2 and SU3 vitiated the requirement for an air flow sequentially through the cyclone units. Finally, it argued that the part of SU3 which separated the finest dust from the air stream was not frusto-conical but "trumpet-shaped" and was therefore out with the claims.

The defendant argued that if the patent included within its scope methods of connection between the cyclones other than "one following the other" directly, then the specification contained no teaching as to what those were and the patent was invalid for insufficiency.

Held, finding the patent valid and infringed:

The inventive concept of the patent in suit

(1) For examining questions of "variants", obviousness and insufficiency, the inventive concept of the patent in suit was a vacuum cleaning appliance in which the dirty air was freed of dirt in cyclones connected in series, the cyclones being of increasing efficiency in their capability of depositing fine dust, the lower efficiency cyclone being upstream of the high efficiency cyclone and having untapered sides, and the high efficiency cyclone have tapered sides.

The addressee and the common general knowledge

(2) A patent was addressed to persons who were likely to have a practical interest in its subject matter or to have to act on the directions given in it for its implementation. The nature of the addressee must therefore depend upon the proper scope of the subject matter of the patent in question. Furthermore, the degree of qualification of the addressee within that subject matter would depend upon the degree of technical sophistication which the subject matter demanded.

(3) It was necessary to establish the common general knowledge of the art which would have a bearing on construction, infringement and the proper assessment of cited prior art. The appropriate level of common general knowledge was the same when each of these topics was adjudicated.

(4) Common general knowledge had both positive and negative aspects. It was customary to consider positive aspects of the knowledge with which the skilled addressee was to be imbued but in certain cases negative aspects of knowledge amounting to prejudice must in reality play their part. Evidence as to what the industry was not doing might be taken into account in the assessment of the common general knowledge.

(5) The addressee of the patent in suit was to be regarded as a qualified engineer with a few years' practical experience of design and development in the domestic and/or industrial vacuum cleaner industry. The common general knowledge of such a person would have included a detailed knowledge of the working, construction and manufacture of vacuum cleaning appliances at the priority date. The mindset within the industry at that time was such that he would have been truly addicted to bag technology and would never have considered any other means of purifying dirt-laden air from a vacuum cleaning operation.

(6) Although cyclone technology would have formed no part of the addressee's active repertoire of skill and knowledge, he would have had latent general knowledge of commercial cyclones, acquired, for example, as a result of graduate training in general mechanical and electrical engineering. He would have understood in general terms how the reverse flow cyclone worked and the function of the frusto-conical shape in the particle separation process. However, he would not have had specialist cyclone expertise, or experience in commercial cyclone theory, design and technology, and he would not have been aware of other types of cyclone such as the uniflow (or straight through) cyclone or cylindrical cyclone.

Construing the patent

(7) The purpose of interpretation of a patent was to ascertain what the patentee's words were intended to convey to the skilled addressee at the application date.

Catnic Components Ltd v. Hill & Smith Ltd [1982] R.P.C. 183 (HL), Improver Corp. v. Remington Consumer Products Ltd [1990] F.S.R. 181 at 189 (Hoffmann J.], Société Technique de Pulvérisation STEP v. Emson Europe Ltd [1993] R.P.C. 513 at 522 (CA), Brugger v. Medic-Aid Ltd [1996] R.P.C. 635 at 649 (Laddie J.), Nobel's Explosives Co. v. Anderson (1894) 11 R.P.C. 519 at 523 (CA per Lord Esher M.R.), Conoco Speciality Products Inc. v. Merpro Montassa Ltd [1994] F.S.R. 99 at 120 (OH, Lord Sutherland], Molins v. Industrial Machinery Co. Ltd (1938) 55 R.P.C. 31 at 39 (CA), Glaverbel S.A. v. British Coal Corp [1995] R.P.C. 255 at 278 (CA), and Biogen Inc. v. Medeva PLC [1997] R.P.C. 1 at 53-54 (HL), referred to.

(8) The word "cleaning" in the phrase "vacuum cleaning appliance" was determinative. The teaching of the patent must be understood in the context of "cleaning" as an ordinary English word. The claimed appliance was intended to clean a surface which had become dirty or covered with unwanted particles. It was not intended to function as an air purifier or dust extractor, although having performed its primary surface cleaning function it must retain the dirt until the user wished to discard it. The appliance was not intended for use only in a domestic environment, however, but also where a more robust and capacious construction might be required.

(9) The "cyclone unit" encompassed more than just the separator vessel (or a part thereof) where dirt was physically separated from dirt-laden air. It might contain more than one separator and/or ancillary apparatus co-operating with a cyclone or cyclones. A unit which did not deposit dust was not a "cyclone unit" within the claims.

(10) The words "in series connection" did not require the output from the low efficiency unit to flow directly into the higher efficiency unit.

(11) The "frusto-conical part" must be tapered sufficiently to separate the dirt but did not have to be geometrically precise. A strictly literal construction would not afford a fair protection for the patentee as required by the Protocol.

Infringement

(12) In the alleged infringement SU2 did not deposit or collect dust or debris and was therefore not a cyclone unit within the claim of the patent in suit. All dirt-laden air entering SU3 had first been pre-cleaned by SU1; SU3 alone was the relevant highest efficiency unit. SU2 did not count so far as infringement was concerned. It did not affect the way the invention worked.

(13) Re-circulation from SU3, if it occurred (and on the evidence it was de minimis), was not relevant to the issue of infringement. SU1 and SU3 were still in series connection. The fact that cleaned air after leaving SU3 might be subjected to further cyclonic cleaning did not avoid infringement. If re-circulation was a variant, it obviously did not affect the way the invention worked and it was not excluded by the claim.

(14) Alternatively, and on the evidence, it would be sound to regard SU2 and SU3 as a single "cyclone unit" within the meaning of the claims. All of the output of SU1 went into such unit; it was undoubtedly in series connection with SU1; and from it dust was deposited and clean air was exhausted to the environment.

(15) The skilled reader would have regarded the "trumpet" shape of the separating zone in SU3 as "frusto-conical" although its notional top and bottom angles differed slightly from a geometrically correct frusto-conical profile.

(16) On the evidence, even if the "trumpet" shape was a variant, it did not affect the way the invention worked. That this was so would have been obvious to the skilled addressee with his basic knowledge of cyclonic separation at the priority date, and there was no particular comprehensible reason why he would have understood strict compliance with the geometric meaning of "frusto-conical" to be required.

Catnic Components Ltd v. Hill & Smith Ltd [1982] R.P.C. 183 at 242 (HL per Lord Diplock), and Improver Corp. v. Remington Consumer Products Ltd [1990] F.S.R 181 at 189 (Hoffmann J.), applied.

Novelty

(17) If a particular word was used in the specification and claims for the subject of the patent in issue, and lack of novelty depended on whether a prior device came within the proper meaning of that word, the question was to be answered realistically in the context of how the word was used in the specification.

Hickman v. Andrews [1983] R.P.C. 147 at 168 (Graham J. upheld by CA), referred to.

(18) In repeating any prior art proposal by experiment with a view to proving lack of novelty, the party seeking to do so must adhere faithfully to the source document interpreted as at the date of its publication. The interpretation was deemed to be the job of the skilled worker, whose knowledge must not be supplemented by knowledge which he might have obtained between that date and the priority date of the patent in issue.

Minnesota Mining & Manufacturing Co. v. Bondina Ltd [1973] R.P.C. 491 at 521 (Sir Lionel Heald Q.C.), followed.

(19) The skilled reader would understand Campbell to be proposing the collection of all the particulate material as the wanted industrial product. There was no mention of dirt and no suggestion of using the device to clean dirty surfaces. The reader would have appreciated that efficient separation and/or agglomeration took place within the conical cyclone alone, itself within the separation chamber. The possibility of cyclonic separation adjacent the walls of the separation chamber was neither described nor illustrated nor even contemplated in Campbell read as a whole.

(20) The experiments failed to prove lack of novelty by realisation of the Campbell disclosure.

(21) Although the apparatus described in the Johnston/Donaldson publications contained cyclone units of successively higher efficiency, it was certainly not a vacuum cleaning appliance. It was a mobile drill which had a dust extractor incorporated into it. The word "cleaning" was nowhere mentioned.

(22) Neither Campbell nor Johnston/Donaldson anticipated the patent in suit.

Inventive step

(23) The skilled man must be assumed to approach a prior art citation with interest, however inimical its proposal might be to his likely way of thinking at the time, but due weight must be given to the likelihood that negative thinking amounting to prejudice would cause him to regard modification to any such proposal with considerable reserve, if not overt scepticism.

(24) If at the relevant time the skilled man perceived no problem which required to be solved, it became difficult to establish the obviousness of taking a particular step which would bring an item of prior art within the scope of the claim under attack.

Hoechst Celanese Corp. v. BP Chemicals Ltd [1997] R.P.C. 547 at 572 (Laddie J.), followed.

(25) There was no evidence of any technical problem at the priority date with using bags in vacuum cleaners to collect dirt separated from dirt-laden air. The viability of other means of doing so would not have been considered. The problem which led to the invention of the patent in suit was the failure of a tapered cyclone in a vacuum cleaner to cope with common domestic debris such as dog hairs and the like. There was no hint of this problem in any of the evidence or cited textbooks or prior art, and there had been no reason or motive to take a step away from the prior art in the direction of the claims.

(26) There must be a limit to the amount of non-inventive change to a proposal which the addressee might legitimately be supposed to perform for the objection of obviousness to succeed. In the present case, reality required a somewhat abbreviated period of tinkering with a particular citation before its adoption or rejection: prejudice was likely to gain the better of patience rather more swiftly than in some other obviousness cases.

(27) Scaling up, scaling down and simple amendment of devices in the vacuum cleaner field were within the competence of the skilled man as part of his common general knowledge. However, on the evidence it was impossible to predict with accuracy the likely technical and practical performance of a separation cyclone merely on the basis of the outcome of a scaling exercise.

(28) The claimed invention was not obvious in the light of any of the cited prior art.

(29) To be valid under section 72(1)(c) of the Act a patent had to be sufficient across its whole width.

Biogen Inc. v. Medeva PLC [1997] R.P.C. 1 at 49 lines 6-9, 53 lines 20-27 (HL per Lord Hoffmann), applied.

(30) Claim 1 of the patent in suit defined with sufficient precision a class of vacuum cleaning appliance sharing the inventive concept as a common principle of operation.

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