Dyson Technology Ltd v Samsung Gwangju Electronics
| Jurisdiction | England & Wales |
| Judge | THE HON MR JUSTICE ARNOLD,MR JUSTICE ARNOLD |
| Judgment Date | 22 January 2009 |
| Neutral Citation | [2009] EWHC 55 (Pat),[2007] EWHC 3228 (Pat) |
| Docket Number | Case No: HC07C02383 |
| Court | Chancery Division (Patents Court) |
| Date | 22 January 2009 |
[2009] EWHC 55 (Pat)
Before: The Hon Mr Justice Arnold
Case No: HC07C02383
IN THE HIGH COURT OF JUSTICE
CHANCERY DIVISION
PATENTS COURT
Piers Acland (instructed by Wragge & Co LLP) for the Claimant
Richard Davis and Christopher de Mauny (instructed by Withers & Rogers LLP) for the Defendant
Hearing dates: 10–12, 15–19 December 2008
Approved Judgment
I direct that pursuant to CPR PD 39A para 6.1 no official shorthand note shall be taken of this Judgment and that copies of this version as handed down may be treated as authentic.
MR JUSTICE ARNOLD:
Introduction
In this claim the claimant Dyson Technology Ltd (“Dyson”) seeks revocation of United Kingdom Patent Nos. 2 424 603 (“'603”) and 2 424 606 (“'606”), which I shall refer to collectively as “the Patents”. Both Patents have a priority date of 29 March 2005. The Patents describe and claim similar inventions in which the key feature is the use of a series of three cyclones, or sets of cyclones, to separate dust from air in a vacuum cleaner.
Dyson alleges that the Patents are invalid on the grounds of lack of novelty or lack of inventive step over the following items of prior art:
i) United States Patent No. 6,238,451 (“Conrad”);
ii) United States Patent No. 5,129,124 (“Gamou”);
iii) Korean Patent Application No. KR 10–2001–0018947A (“LG”);
iv) Japanese Utility Model No. 52–014775 (“Sanyo”); and
v) Dyson's DC07 and DC08 vacuum cleaners.
The defendant Samsung Gwangju Electronics Co. Ltd (“Samsung”) has applied to amend both Patents. The applications are unconditional in the sense that they are not conditional upon the Court concluding that the Patents as granted are invalid. Despite the applications to amend, Samsung maintains that the granted Patents are valid. Dyson opposes both applications on the grounds that the amendments will result in additional matter being disclosed. Dyson also contends that the claims as proposed to be amended are still invalid.
Samsung asserted that many of the subsidiary claims in both Patents as proposed to be amended were independently valid over one or more items of prior art. In the run up to trial, Samsung identified two lists of claims, an “A” list consisting of eight claims which it considered to be of particular importance and a “B” list consisting of the remaining 20 claims asserted to be independently valid. In addition, Samsung relied upon five granted claims. At trial attention was focussed on the A list of proposed amended claims. It was agreed that I should first determine the issues arising in relation to those, and that if any separate issues in relation to the B list and granted claims remained after that I should hear further argument in relation to those.
Technical background
Cyclones have been used to separate solids and liquids from gases for a very long time. Indeed, the first patent on cyclone separators was granted to O.M. Morse as long ago as 1886. By the mid 20 th century cyclonic separation was a well-established technology which was widely used in many sectors of industry. Nevertheless, in recent years there has been an increased interest in cyclones as a result of their widespread use in domestic vacuum cleaners. This use was pioneered by Sir James Dyson (see Dyson Appliances Ltd v Hoover Ltd [2001] RPC 26 at [12]-[17] and [44]), although it turns out that one of the items of prior art in the present case (Sanyo, which was not cited in that case) pre-dates his work. Despite the smaller size of cyclones used in domestic vacuum cleaners, the technical principles involved are essentially the same as in industrial cyclones.
In a cyclone, a gas such as air is caused to spin in a vortex. Particles such as dust entrained in the air accelerate towards the axis of rotation. This centripetal acceleration is equal to V 2/r (where V = tangential velocity and r = radius of rotation). As a result, the particles experience an apparent force directed away from the axis of rotation which is generally referred to as “centrifugal force”. The centrifugal force causes the particles to migrate outwards with respect to the air. Thus particles concentrate in the outer layers of the spinning air and the air in the centre layers is effectively cleaned.
The efficiency with which a cyclone separates dust particles depends, amongst other factors, on both the diameter of the cyclone (which determines the centrifugal force applied to the dust) and the inertia (relating to the size and density) of the particle (which determines the dust's response to that centrifugal force). In general, smaller particles are separated less well than larger particles. Thus the aerosol emitted from a cyclone will have a smaller average size than the aerosol entering it. Small diameter cyclones separate smaller particles more effectively than large diameter cyclones. This is because, as a result of the smaller radius of rotation, they apply a higher centrifugal force.
In operation, the gas passing through a cyclone is subject to a pressure drop that varies as the square of the flow rate. At constant flow rate the pressure drop increases rapidly as the diameter of the cyclone is reduced. A high pressure drop will affect the suction power of a vacuum cleaner, and thereby reduce the ability of the vacuum cleaner to pick up dust and dirt from the surface to be cleaned.
There are two main types of cyclone design. The first is known as a reverse flow cyclone. This normally involves the air spinning down through the cyclone body, then reversing and travelling up through the middle of the exterior vortex and out through an outlet known as a vortex finder. These cyclones are generally either cylindrical or frusto-conical. A frusto-conical cyclone is simply one in which the cyclone is conical, but the tip of the cone is not present. Most high efficiency designs of cyclones are frusto-conical reverse flow cyclones, for example as shown below:
The behaviour of the gas and particles in a frusto-conical reverse flow cyclone may be summarised as follows:
i) The gas enters the cyclone chamber, usually via a tangential inlet, and flows in a spiral downwards. This moves down the outer region of the chamber, creating an outer vortex.
ii) The centrifugal force exerted on the dust causes it to migrate with respect to the gas and so to be concentrated in the slower moving region of flow close to the wall, the boundary layer. The major portion of the particles is concentrated in this region as the gas spirals downwards.
iii) Still spinning, the gas then reverses its direction of axial flow in order to leave the unit via the vortex finder.
iv) This inner vortex has the same tangential direction of rotation, but the reverse axial direction of flow, compared with the outer vortex.
v) The pressure distribution within the cyclone causes the dust in the boundary layer to flow along the internal surface of the cyclone to the cone exit. After exiting the cone, dust is normally collected in a hopper or some other receptacle.
The second type of cyclone is an axial or uniflow cyclone. In such a cyclone, air enters one end of the cyclone via either a swirl vane or a tangential inlet, spins through the cyclone (which is normally cylindrical) and leaves the cyclone at the other end. Particles in the airflow are concentrated close to the wall, and the cleaned air is removed from the centre of the unit. A vaned axial flow cyclone looks like this:
It is common for multiple cyclones to be arranged in parallel with each other. Arranging cyclones in parallel provides advantages in terms of separation efficiency for a given pressure drop. Dividing the total gas flow into several smaller streams allows the deployment of smaller diameter and hence more efficient cyclones without significantly increasing the overall pressure drop. It is important to ensure that the airflow divides reasonably evenly between the parallel cyclones, since an imbalance in the flow rate can substantially degrade the separation efficiency of the system as a whole.
It is also common for two cyclones to be arranged in series with each other (or for sets of parallel cyclones to be arranged in series). When cyclones are operated in series, the first stage cyclone has the opportunity to collect the large, easy to collect particles. Accordingly, it will often be a low efficiency design with a low pressure drop. Nevertheless, it is common for the first stage cyclone to collect the major part ( say 80–90%) of the total dust presented to the vacuum cleaner. The second stage cyclone is left with the more difficult fine particles that have escaped the first stage, and so is often designed to be of a higher efficiency i.e. capable of capturing smaller particles. It is not essential, however, for a second stage to be of higher efficiency for it to collect sufficient material to improve the overall collection efficiency of the vacuum cleaner. If two identical cyclones are connected in series, 50% of a particle size collected with 50% efficiency will pass through the first stage to the second stage. Of the material passing through the first stage, 50% will be collected by the second stage, so that the overall collection is 75%.
'603
The specification of '603 begins at page 1 lines 3–5 as follows:
“This invention relates to a multi-cyclone dust separator and to a vacuum cleaner using the same, and in particular to a multi-cyclone dust separator comprising a plurality of cyclones to separate dust particles sequentially according to size, and to a vacuum cleaner using the same.”
The specification goes on at page 1 lines 9–10 to say that an “example of a vacuum cleaner incorporating such a cyclone dust...
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