BAILII [Home] [Databases] [World Law] [Multidatabase Search] [Help] [Feedback]

England and Wales High Court (Patents Court) Decisions

You are here: BAILII >> Databases >> England and Wales High Court (Patents Court) Decisions >> Wagner International AG & Ors v Earlex Ltd [2012] EWHC 984 (Pat) (18 April 2012)
Cite as: [2012] EWHC 984 (Pat)

[New search] [Context] [View without highlighting] [Printable RTF version] [Help]

Neutral Citation Number: [2012] EWHC 984 (Pat)
Case No: HC 10 C 01989


Royal Courts of Justice
Strand, London, WC2A 2LL

B e f o r e :


(3) J. WAGNER GmbH

- and -



Richard Davis and Ben Longstaff (instructed by Field Fisher Waterhouse LLP) for the Claimants
Thomas Mitcheson (instructed by Redd Solicitors LLP) for the Defendant
Hearing dates: 13th to 16th March 2012



Crown Copyright ©

    Mr Justice Floyd:

  1. The claimants (together "Wagner" except where it is necessary to distinguish between them) bring this action for patent infringement against the defendant ("Earlex"). The patent in suit is European Patent (UK) No 0596939. The patent relates to paint spray guns. Earlex deny infringement and counterclaim for revocation of the patent on the grounds of added matter, lack of novelty and obviousness.
  2. Paint spray guns and spray painting

  3. Spray painting is a well established art. A typical spray painting system includes an air supply source, paint supply, a hand held spray gun and nozzles or air caps in the gun to obtain different spray patterns. The function of the air supply is to draw the paint out of the paint nozzle, atomise the paint into a fine mist or spray and carry the paint to the surface being painted. The paint supply may be in a separate container connected by a hose to a spray gun. Alternatively the container may be part of the hand held device.
  4. "Conventional" systems ("conventional" is a term of art) are high pressure systems, driven by a compressor. This action is not primarily concerned with conventional systems but with another known type of system called HVLP, HVLP stands for high volume, low pressure. HVLP systems are driven at a much lower pressure than conventional systems, typically provided by a turbine. The lower pressure of HVLP has advantages such as less splash back or overspray. However, the turbines used in HVLP cannot easily cope with changes in back pressure, for example caused by blocking the passages. For this reason, in many turbine-powered HVLP systems the air supply is continuously on, and the spray gun trigger only opens and closes the paint flow valve. This is known as a "continuous bleeder" type of system.
  5. The focus of this action is the air cap. Air caps were often designed so as to enable the user to alter the shape of the spray emerging from the gun, and hence the shape of the area of impact of the paint on the substrate being painted. I will refer to this latter shape as the "footprint". One such arrangement, well known in the prior art, was of an air cap which could be adjusted to produce a circular footprint, or squashed elliptical footprints either in the vertical or horizontal sense. This was achieved by channelling air from the air supply into (usually) two "horns" on the front of the air cap, so that the air is directed inwardly through holes in the horns at the emerging paint cone. The shape of such a squashed paint spray is referred to as fan-shaped. By rotating the air cap, the device can be set to a configuration in which air is not permitted to emerge from the horns, yielding a cone shaped spray and a circular footprint. Alternatively it can be rotated to two other positions in which air is permitted to emerge from the horns, giving horizontal and vertical fan-shaped sprays and elliptical footprints.
  6. In addition to air holes in the horns, used for shaping purposes, air holes may be included in the air cap for cleaning purposes so as to prevent paint accumulating on the air cap and then being blown off as blobs so as to spoil the finish on the substrate being painted.
  7. The patent in suit

  8. The patent in suit addresses a problem which arises from the change in back pressure when an air cap is changed from the elliptical configuration to the circular configuration. In the circular configuration the cross-sectional area through which air can escape is more restricted than in the elliptical configuration, because in the circular configuration the air holes in the horns are blocked. Changing from the elliptical to the circular footprint is therefore accompanied by an increase in back pressure. The patent points out at column 1 line 28-31 that this back pressure "reduces the efficiency of the fan motor and increases wear on the motor".
  9. The solution proposed by the patent is to provide venting passages in the air cap which are open when the air cap is set for the circular footprint (when the shaping passages are closed) but closed when the air cap is set for the elliptical footprint (when the shaping passages are open). The venting passages are said to relieve back pressure to the air source.
  10. The claims in issue

  11. Only claims 1 and 13 matter. I set them out below without reference numerals, but with added lettering which I will use only for identification purposes later in this judgment.
  12. Claim 1

  13. Claim 1 is to an air cap system for a paint spray gun comprising:
  14. 1A (a) an air cap including:
    1B (1) a central passage coaxially aligned with a central longitudinal axis of the air cap,
    1C (2) at least one paint spray shaping passage in the air cap configured and arranged for directing a flow of pressurized air against a stream of atomized paint discharged from the central passage so as to alter the shape of the paint spray, and
    1D (3) at least one venting passage configured and arranged so as to be ineffective for directing a flow of pressurized air against a stream of atomized paint discharged from the central passage so as to alter the shape of the paint spray, and
    1E (b) a blocking means effective for blocking air flow through the paint shaping passage while permitting air flow through the venting passage when in a first position and permitting air flow through the paint shaping passage while blocking air flow through the venting passage when in a second position;
    1F characterized in that (c) at least one venting passage is located in the air cap;
    1G (d) the blocking means is operable for directing air flow between the paint shaping passage and the venting passage independently of the flow of a fluid through the central passage.

  15. Claim 13 is to:
  16. 13A A method for altering the spray pattern of atomized paint sprayed from a paint spray gun while maintaining a substantially constant level of back pressure within the air flow path of the spray gun comprising the step of
    13B (a) positioning an air cap, located proximate the distal end of a paint spray nozzle, relative to a blocking means located upstream from the air cap, as between a first position and a second position wherein,
    13C (i) the air cap is in sealed fluid communication with an air flow path within the paint spray gun in both the first and second positions,
    13D (ii) the first position permits air flow through paint shaping passages in the air cap so as to shape atomized paint sprayed through a central passage in the air cap while blocking air flow through venting passages in the air cap, and
    13E (iii) the second position permits air flow through the venting passages in the air cap so as to vent pressurized air from the paint spray gun without shaping atomized paint sprayed through the central passage in the air cap while blocking air flow through the paint shaping passages in the air cap.

    The skilled addressee and the common general knowledge

  17. The patent is addressed to a designer or team of designers working in the field of spray painting equipment. Such a person would be familiar with the basic principles of physics as they apply to spray painting. This would include knowledge of compressor and turbine operated paint spray systems.
  18. Such a person would know how the variable pattern air cap which I have described works. He or she would know how the rotation of the cap opens and closes the air passages in the horns. This, as he would know, is accomplished by use of a blocking plate, usually in cruciform shape, behind the air cap and cooperating with it. He would also know that holes in the air cap can be used for cleaning.
  19. The witnesses

  20. Wagner served witness statements from a number of witnesses to deal with the allegations of prior disclosure and use. The evidence of Andrea Slusser, Philip Bilney, Thomas Craig and Sandra Swanson was not challenged. Wagner elected not to call Mr Svendsen, who is the sole inventor, and so I have disregarded his evidence, except where it was confirmed by Mr Cooper. In the end, of these witnesses, only Mr Cooper was called to give oral evidence. Mr Cooper was Vice President of Marketing at Wagner US, the second claimant, at the time of the alleged prior disclosures and use. Mr Cooper was an obviously honest and careful witness, but who had little recollection of what happened in connection with the alleged prior use except insofar as he could explain what might be expected to have happened based on the contemporary documents.
  21. Earlex served a witness statement of Lon McCloskey, a former employee of Wagner US which they relied on by way of a Civil Evidence Notice. I have therefore had no opportunity to form a view as to the reliability with which he recollected the events in question.
  22. Both sides called an expert engineer. Wagner called Mr Anthony Bate, a consulting engineer who worked in the paint spray industry for many years. Mr Bate is the named inventor on a number of patents belonging to his former employers, De Vilbiss and later Illinois Tool Works. He struck me as an intensely practical man with enormous experience of paint spray technology. He was very frank in his answers. On practical matters I found his evidence to be brimming with common sense. I formed the impression that some of his theoretical explanations were out of his comfort zone, and in practice he would be far more likely to have performed tests rather than rely on theoretical arguments.
  23. Earlex called Mr Timothy Hopper. Mr Hopper is the Technical and Development director of Earlex. Together with his ex-wife he owns half of the shares in Earlex. Mr Davis said that he had failed to disclose in his expert report the full extent of his interest in Earlex. Whilst this is true, in that Mr Hopper did not give figures for his shareholding, or explain the extent of his financial involvement with the company, I am satisfied that there was no intent to hide anything. Indeed Mr Hopper recognised that the attack was coming, and explained how he had made a particular effort to comply with his duty to the Court as an independent expert, even if this involved giving answers which could adversely affect Earlex. There is no doubt in my mind that he complied with that duty.
  24. Construction

  25. Such issues as there were relating to construction of the claims can be dealt with in the context in which they arise. There was no dispute about the principles to be applied to the construction of a patent, which are those stated by the House of Lords in Kirin Amgen v TKT [2005] RPC 9. Helpful guidelines on the application of those principles are contained in the judgment of the Court of Appeal in Virgin Atlantic v Premium Aircraft [2010] FSR 10 at paragraph 5. I have had regard to those guidelines here.
  26. Infringement

  27. The alleged infringement is the Earlex HVLP spray gun. Two versions of the air cap in the Earlex HVLP spray gun are described in the defendant's amended product description, the Original Design and the Modified Design.
  28. The Original Design of air cap consists of a single piece of moulded plastic with a circular base. It has a hole through the centre for the paint spray, and two horns protruding from opposite sides of the base. Each horn has two holes (one large and one small) in its face, which connect to an air passage from the underside of the base. There are four holes in the face of the base, positioned on either side of each horn. The holes are on axes separate from, though parallel with the axis of the air cap, i.e. they are not angled in or out from the axis of the device. These are venting holes which are opened when the shaping holes are closed.
  29. The Modified Design is similar to the Original Design but without the holes in the face. There are four castellations located on the front flange of the base, and four channels on the underside of the base running from the edge of the base towards (but not connecting to) the central hole.
  30. Integer 1D/13E

  31. Earlex contends that in the Original Design there are no venting passages in the sense meant by the claim, and that the holes in the Earlex device are not "ineffective for directing a flow of pressurized air against a stream of atomized paint discharged from the central passage so as to alter the shape of the paint spray".
  32. The first point is based on the suggestion that Earlex's holes are not angled away from the axis. The point raises a question of construction, namely whether "venting passages" are required expressly or by necessary implication to be angled away from the axis. Mr Mitcheson relied on the following passage in the specification at column 3, lines 47-57 (emphasis added):
  33. "The venting passages are preferably angled outwardly at an angle of 15 from an axis of the air cap to prevent air venting passages from interfering with the spray pattern formed by paint exiting nozzle and air exiting central aperture. It is to be understood that other angles may be used and still be within the scope of the present invention provided that the air escaping from the venting passages does not interfere with the paint spray pattern."
  34. Mr Mitcheson's point is that the specification does not contemplate that the angle could be zero. I reject this argument. It seems to me that the term "venting" passage is a functional term which is further qualified by a functional requirement (not altering the shape of the paint spray). The skilled person would, in my judgment, understand that what was required was holes which achieve venting, and achieve it without altering the shape of the paint spray pattern.
  35. The real question is therefore whether the air emerging from the Earlex holes in use alters the shape of the paint spray. This raises a further question of construction, namely what is meant by "the shape of paint spray". It matters because the Product Description indicates that when airflow to the horns is cut off and air instead flows through the venting holes "an approximately circular paint spray pattern is generated". Read literally, therefore, there is no substantial change in the "shape" of the paint spray: it remains circular, although the size of the circle may have changed, and the distribution of paint within the circle may have changed as well. Mr Mitcheson accepts that if the test for infringement is whether the footprint is approximately circular whether or not the venting passages are present, then there is infringement. However he contended that the effect of the air emerging from the face holes in the Earlex device would be bound to have some impact on the stream of paint emerging from the central aperture, and in consequence on the paint spray pattern. It would be necessary to carry out tests to see whether this was so to any material extent, and Wagner had not adduced any admissible evidence of such a test.
  36. In my judgment the skilled person would understand the term "shape of the paint spray" in the patent in the same sense as the passages in the specification which refer to the paint spray pattern. I agree with Mr Davis that the skilled person would not suspect that the terms are being used in a different sense: they are being used interchangeably. However I disagree that the patent is only concerned with shape in the broad sense which he contended for. Any interference with the air and paint stream emerging from the central aperture is treated by the patent as an interference with the paint spray pattern. The matter is not therefore concluded by the concession as to approximate circularity in the Product description.
  37. Mr Bate was cross-examined about the impact of the air from the venting passages on the paint spray. He recognised that the air streams would collide, but expressed the opinion that there would be only minimal effect on the shape of the spray, given the distance at which confluence would occur. I found this evidence of theoretical opinion unconvincing in the light of the large numbers of factors which could affect the result. Indeed it was Mr Bate's own evidence that this was an art in which one needed to test. Mr Hopper's evidence was that he would expect there to be some differences, and to find out one would have to do tests.
  38. It follows, in my judgment, that Wagner has failed to prove infringement in relation to this feature in relation to the Original Design.
  39. On the Modified Design the air is emitted through an annulus, interrupted only by the four castellations on the base of the air cap. Mr Hopper very fairly accepted that the size of the spot would be essentially the same with or without the venting passages. Accordingly, the Modified Design has this feature.
  40. Integer 1G/13A

  41. I approach these features on the basis that what is required is that the venting passages and shaping passages have the same cross sectional area. On that basis, it is accepted by Earlex that the evidence established that the Original Design had this integer. For the Modified Design there is no evidence that the cross sectional areas are the same. Indeed the evidence showed that one could not say whether the volume of air flowing through the venting passages in the Modified Design was greater than or smaller than that which passed in the Original Design. Wagner's expert simply assumed that the air flows were arranged to be the same, without any evidence. Wagner have therefore failed to establish that the Modified design has this feature.
  42. Conclusion on infringement

  43. Although for different reasons, neither Earlex design infringes claim 1 or claim 13.
  44. Validity

  45. Validity is attacked on the grounds of added matter and of lack of novelty or obviousness over various alleged prior uses by Wagner and one documentary citation.
  46. Added Matter

  47. A patent will be invalid for the objection known as "added matter" if "the matter disclosed in the specification of the patent extends beyond that disclosed in the application for the patent as filed" (Patents Act 1977, section 72(1)(d)). The relevant law has been compendiously summarised by Arnold J in Abbott Laboratories Ltd v Medinol Limited [2010] EWHC 2865 (Pat) at [251] [253]. The Enlarged Board of Appeal has recently, in Decision G2/10, described the summary of the law of added matter in its two earlier decisions G3/89 and G11/91 as the "gold standard". Those decisions make clear that a patent may only be amended:
  48. "within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge and seen objectively and relative to the date of filing, from the whole of these documents as filed."
  49. In the present case there is no change to the text of the specification between the application as filed and the granted patent. There has, however, been some significant re-writing of the claims. The defendants say that the following phrases in the amended claims add matter:
  50. i) in integer 1D and 13E: "so as to alter the shape of the paint spray" and "without shaping atomized paint";

    ii) in integer 1E and 13B: "blocking means";

    iii) in integer 1G: "the blocking means is operable independently of the flow of fluid through the central passage";

    iv) in integer 13A: "maintaining a substantially constant level of back pressure";

    v) in integer 13C: "sealed fluid communication" .

    Integer 1D/13E

    Disclosure of the application as filed

  51. In the application as filed, it is the "spray pattern formed by paint exiting from nozzle 22 and air exiting central aperture 36" which is said to be unaffected by the air from the venting passages: see page 5 lines 28 to 33; see also page 5 line 33 to page 6 line 2. Claim 17 describes the venting passages as directing air away from the "spray pattern".
  52. By contrast the shaping passages are said (page 7 lines 5-6) to alter the shape of the paint spray pattern.
  53. Disclosure of the patent

  54. The phrase objected to in the claim requires that the air from the venting passages be ineffective to alter the "shape of the paint spray".
  55. Discussion

  56. The defendants contend that the change in language from "spray pattern" to "shape of the paint spray" results in added matter. They contend that "spray pattern" can include other changes to the paint spray output that do not alter its shape, such as changes in the size of the footprint or the intensity or evenness of the resulting finish. They contend that what is disclosed in the application as filed is that the air flow from the venting passages does not interfere at all with the air stream emerging from the central aperture. By the change of language, it is suggested that something less will do, namely changes to the pattern may occur provided that they do not interfere with the shape.
  57. I am not persuaded by this point. I have come to the conclusion that the phrase in the claim would not be understood to mean anything different from the paint spray pattern. The skilled reader would understand from the application that the air from the venting passages did not affect the paint and air "exiting the nozzle". I do not think that the words objected to in the claim amount to a disclosure of anything more. Accordingly there is no added matter.
  58. Integer 1E/13B

    Disclosure of the application as filed

  59. In the application as filed, a blocking plate is described having the common cruciform configuration: see figures 4-6 and accompanying description. Although claim 1, the product claim, claims the invention by reference to a blocking plate, claim 17, which is to a method of selectively relieving back pressure, calls for a "selectively blockable shaping passage" without reference to any particular form of blocking means.
  60. Disclosure of the patent

  61. The patent calls for a "blocking means effective for blocking air through the paint shaping passage."
  62. Discussion

  63. The defendants argue that the introduction of the term "blocking means" impermissibly generalises the concept of a blocking plate. I do not agree. In my judgment the general notion of blocking the shaping passages was present in claim 17. The notion of a blocking means, not necessarily a plate, is disclosed by claim 17. Nothing more is disclosed by the patent.
  64. Integer 1G and 13A

    Disclosure of the application

  65. A number of passages in the application as filed are of importance here. At page 1 lines 7-10, the venting passages are said to:
  66. "allow air to escape to reduce back pressure to the air supply when air is blocked through a set of spray pattern shaping passages"
  67. The application goes on to say that, in the past, spray guns with shaping passages had allowed the pressure to build up when the shaping passages were blocked. Then, at page 6 lines 31 to page 7 line 6, it states:
  68. "Air flow through the venting passages 54 is blocked by plate 18 when the air cap 10 is disposed in either the second or third position. Thus it may be seen that air flow is maintained in each of the first, second and third positions. In the first position, air flow is directed through the venting passages 54 which relieves the back pressure to the air source while the primary shaping passages 46 are blocked. In the second and third positions, venting passages 54 are blocked while the primary shaping passages 46 conduct air . relieving back pressure to the air source."

    Disclosure of the patent

  69. I take these two integers together, although they are expressed in somewhat different words. I can do so because Mr Davis submits, and I accept, that the two integers objected to mean the same thing. The feature in claim 1 requires that, irrespective of the position of the air cap, the flow of air through the central aperture remains unchanged. To achieve this one would have to ensure that the air flow through the venting passages (when in use) was the same as the air flow through the shaping passages (when in use). In such an arrangement the back pressure would be unchanged, which is the way this aspect of the invention is claimed in claim 13.
  70. Discussion

  71. There is no explicit disclosure in the application as filed of the features claimed, because it is nowhere expressly stated that the air flow through the venting passages when the shaping passages are closed is the same as the air flow through the shaping passages when the venting passages are closed. Accordingly, Mr Davis is constrained to submit that the feature is implicit in the disclosure of the application as filed. Mr Davis accepts that it is not a necessary incident of constructing the apparatus described that the two airflows would be the same. However he says that one can derive that teaching directly and unambiguously from the disclosure of the application. He drew particular attention to the use of the word "maintained" at page 6 line 35, and to the fact that one could switch from relieving back pressure with the venting passages to relieving it with the shaping passages. He submitted that this was the same pressure, namely that caused by the circular pattern, and that accordingly the case where the two were the same was implicitly described.
  72. Despite Mr Davis' able submissions, I am unable to find in the application as filed any implicit disclosure of the fact that the venting and shaping air flows are the same or substantially the same. Whilst it would no doubt be an obvious application of the teaching of the application as filed to design the apparatus so that the cross sectional areas of the venting and shaping holes were the same, this is not expressly taught. The word maintained does not imply that the air flow is maintained at the same level. To make express that which is not implicit represents an additional teaching, nowhere to be found in the application. There is accordingly added matter in this respect.
  73. Integer 13C

    Disclosure of the application

  74. The application discloses by reference to the figures that the air cap is connected to other parts of the gun. It is clear that the airflow passes through it. It is also fair to point out that blocking the passages in the air cap causes back pressure to build up. There is no express disclosure that the air cap is in "sealed fluid communication" with an air flow path within the paint spray gun.
  75. Disclosure of the patent

  76. The patent clearly discloses, in claim 1, that the air cap is in sealed fluid communication with the air flow path
  77. Discussion

  78. Mr Davis again submitted that this was implicit, because it simply meant that the relevant communication path did not leak. Even if I accept Mr Davis' submission as to what the phrase means, I do not accept that it is directly and unambiguously derivable form the application as filed that the path does not leak. The application does not address the question of sealed communication: it is simply silent on the point. Again, whilst it may be obvious to avoid leaks, the application, unlike the granted patent, does not tell the reader this is so. Matter has been added in this respect as well.
  79. Claim 7

  80. Mr Mitcheson also drew attention to a feature of claim 7, that the blocking plate and air cap are rotatable "relative to one another". He submitted that the application disclosed only that the air cap is rotatable relative to the blocking plate, and not vice versa. In view of my conclusions on the other claims I will say only that I was not persuaded by this point.
  81. Lack of novelty and obviousness: law

  82. Section 2(1) of the Patents Act 1977 provides so far as material:
  83. "2(1) An invention shall be taken to be new if it does not form part of the state of the art.
    (2) The state of the art in the case of an invention shall be taken to comprise all matter (whether a product, a process, information about either, or anything else) which has at any time before the priority date of that invention been made available to the public (whether in the United Kingdom or elsewhere) by written or oral description, by use or in any other way."
  84. Section 3 provides:
  85. "An invention shall be taken to involve an inventive step if it is not obvious to a person skilled in the art, having regard to any matter which forms part of the state of the art by virtue only of section 2(2) above."
  86. This part of the law of patents was reviewed by the House of Lords in Synthon v SKB [2006] RPC 10. There are two requirements for a claim to be anticipated by a prior document: disclosure and enablement. As to disclosure, Lord Hoffmann, who gave the leading judgment, began by citing passages from what he described as two judgments of "unquestionable authority": the speech of Lord Westbury LC in Hills v Evans (1862) 31 LJ Ch (NS) 457 at 463 and the judgment of the Court of Appeal in General Tire and Rubber Co v Firestone Tyre and Rubber Co Ltd [1972] RPC 457 at 485-486. At paragraph 22 Lord Hoffmann says this:
  87. "If I may summarise the effect of these two well-known statements, the matter relied upon as prior art must disclose subject-matter which, if performed, would necessarily result in an infringement of the patent. That may be because the prior art discloses the same invention. In that case there will be no question that performance of the earlier invention would infringe and usually it will be apparent to someone who is aware of both the prior art and the patent that it will do so. But patent infringement does not require that one should be aware that one is infringing: "whether or not a person is working [an] ... invention is an objective fact independent of what he knows or thinks about what he is doing": Merrell Dow Pharmaceuticals Inc v H N Norton & Co Ltd [1996] RPC 76, 90. It follows that, whether or not it would be apparent to anyone at the time, whenever subject-matter described in the prior disclosure is capable of being performed and is such that, if performed, it must result in the patent being infringed, the disclosure condition is satisfied. The flag has been planted, even though the author or maker of the prior art was not aware that he was doing so."
  88. In relation to enablement where the prior subject matter consists of a product, Lord Hoffmann said this, citing Decision G1/92:
  89. 29 Indeed, when the prior art is a product, the product itself, though dumb, may be enabling if it is "available to the public" and a person skilled in the art can discover its composition or internal structure and reproduce it without undue burden: see the decision of the Enlarged Board of Appeal in Availability to the Public [1993] EPOR 241, para 1.4.
  90. However, the disclosure to be derived from the public availability of an article depends on the extent to which the public have unrestricted access to it. That which the public do not have access to is not "made available to the public". In Lux Traffic Signals v Pike [1993] RPC 107, Aldous J said this at page 134, having reviewed the EPO authorities:
  91. "There is a difference between circumstances where the public have an article in their possession to handle, measure and test and where they can only look at it. What is made available to the public will often differ in those circumstances. In the latter case it could be nothing material; whereas in the former the public would have had the opportunity of a complete examination.
    In the case of a written description, what is made available to the public is the description and it is irrelevant whether it is read. In the case of a machine, it is that machine which is made available and it is irrelevant whether that machine is operated in public. A machine like a book can be examined and the information gleaned can be written down. Thus what is made available to the public by a machine, such as a light control system, is that which the skilled man would, if asked to describe its construction and operation, write down having carried out an appropriate test or examination. To invalidate the patent, the description that such a man would write down must be a clear and unambiguous description of the invention claimed."
  92. As to lack of inventive step, the well known structured approach is that set out by Jacob LJ in Pozzoli SpA v BDMO SA [2007] FSR 37:
  93. "(1) (a) Identify the notional "person skilled in the art";
    (b) Identify the relevant common general knowledge of that person;
    (2) Identify the inventive concept of the claim in question or if that cannot readily be done, construe it;
    (3) Identify what, if any, differences exist between the matter cited as forming part of the "state of the art" and the inventive concept of the claim or the claim as construed;
    (4) Viewed without any knowledge of the alleged invention as claimed, do those differences constitute steps which would have been obvious to the person skilled in the art or do they require any degree of invention?"

    The alleged prior use/disclosure

    Wagner's FineCoat sprayer

  94. Wagner entered the market for HVLP paint sprayers when it purchased the assets of an insolvent company called Capspray. In November 1989 Wagner decided to commence a project for the manufacture and marketing of an HVLP sprayer for the consumer market. The name FineCoat was chosen and steps were taken to register the name as a trade mark. The aim was to have a prototype ready for the National Hardware Show in August 1990, with shipment starting in April 1991. A working prototype product was introduced to the trade and customers at the National Hardware Show in August 1990, but it is now common ground that it did not at that stage include the features of the invention. The product was included in Wagner US' 1991 Marketing Program, a document which mapped out the marketing plan for that year, but which was produced in 1990.
  95. From the outset of the project it was intended to obtain UL approval. UL stands for Underwriters Laboratories Inc. UL undertook consumer testing for safety, and approval could be indicated by applying stickers to the product.
  96. In September 1990 it was reported that the current fan tests showed that the turbine motor was running hot, in excess of the UL recommended temperature. In October 1990 a Wagner US document records a number of action items, e.g. "Can we save any money or reduce temperature rise with a lower performance turbine with 200 hour life?"; "Complete testing air cap hole sizes for performance and heat rise" and "Prototype air caps to test patterns and heat rise". By October 1990 it is clear that the design of air cap including the venting holes had been arrived at, although testing was still continuing in November. A drawing dated 22nd October 1990 is really conclusive on this.
  97. By January 1991 the plan was to have a pilot run in April 1991 with production commencing in June and shipment to trade in July. On 4th April the pilot run was recorded as being "within weeks". On 10th May pilot production was predicted to begin on May 20th, conditionally on everything going well with pilot moulds. The May Project Review records that the pre-production would occur in that month. In May or early June Wagner US were able to ship 10 European units to Germany.
  98. The July Project Review records that pre-production took place in May 1991. This is used by Earlex to suggest that there were two pilot runs, one in May and one in July. I accept that is so. It is clear from a July 16th memo that a further 50 piece pilot run began on Thursday July 17.
  99. The July 16th memo also records that UL official approval was expected on July 18th, and the first 3500 boxes were to be stickered. On 30th July UL issued a letter granting formal approval. Mr Cooper accepted that this would have been preceded by informal notice by telephone.
  100. Wagner US' records show that several hundred units were shipped in the fiscal month July 1991. However, the fiscal month does not end until the end of the week, namely Saturday August 3rd. Those records, therefore, do not demonstrate conclusively that the units were shipped before 30th July 1991, the priority date of the patent.
  101. In the end, I was not persuaded that the units were shipped before 30th July. I realise that Mr Cooper's evidence was that there would have been no difficulty shipping the 751 units by August 3rd even if approval had only been notified on the 2nd. The shipping department was therefore capable of reacting quickly to an order to release the product. But there is simply no reliable evidence of when in the period 29th July to August 3rd the units were in fact shipped. They could have been shipped before 30th July, but I am not persuaded on the balance of probabilities that they were.
  102. The March 1991 Home Center Show

  103. In the meantime, however, the 1991 Home Center Show took place between 24th and 27th March 1991 in Chicago. At least one prototype example of the FineCoat sprayer, with the venting passages in the air cap according to the invention, was present on the exhibition stand and was demonstrated to members of the public visiting the show. Moreover members of the public could and did use the sprayer themselves. The face holes in the air cap would be visible to anyone who looked at the gun with interest.
  104. Whilst there was some evidence that there were representatives of Wagner present who would have been prepared to explain what the face holes in the air cap were for if they had been asked, there is no evidence that anyone was in fact told what the holes were for. What is more there is no contemporaneous evidence that any particular prominence was being given to the existence of the air holes, as opposed to the overall performance of the device.
  105. However, I have no hesitation in concluding that a spray gun device which in fact fell within the scope of the claims of the patent was demonstrated publicly at the Show.
  106. The field trials

  107. The evidence about field trials of the units is limited. In March 1991 a manuscript note appears recording "Set up 4 field tests in early May". It is clear that the field tests took place in April or May 1991. In July a memo records that marketing was to issue a detailed test report separately and the general consensus was positive.
  108. I consider that the field trials provide too insecure a foundation for attacking the validity of the patent. It is not established on the balance of probabilities that the field trials were conducted in public, or that those who conducted them were free in law and equity to make use of the information derived from them. I therefore propose to say no more about them.
  109. Lack of novelty over the disclosure at the Home Center Show

  110. Although the skilled person who examined the FineCoat device at the Home Center Show in March 1991 would have seen the holes in the front of the air cap, I am not persuaded that he would as a result have the invention disclosed to him. For example the skilled person would need to be able to deduce clearly and unambiguously from the disclosure at the Show:
  111. i) how the venting holes were connected up to the air supply;

    ii) whether the air from the venting holes did not interfere with the paint spray.

  112. It follows that I do not consider that the disclosure at the Show amounted to a disclosure of the invention of claims 1 and 13.
  113. Obviousness over the disclosure at the Home Center Show

  114. Although Mr Mitcheson put his case of obviousness over the disclosure at the show in a number of ways, the most compelling, to my mind, was the following. He said, as Mr Bate accepted, that it would be possible from the examination of the device at the Show to estimate the diameters of the holes and their relative positioning on the air cap. The skilled person would think it likely that the device included a standard cruciform blocking plate. This would enable the skilled person to recreate the device by drilling four holes in the correct places on the air cap and place it on the front of a standard spray gun. Accordingly the skilled person who sought to recreate what he saw at the Show would be working the invention. Mr Bate's cross-examination, went like this, at first:
  115. Q. What I have asked you, Mr. Bate, is if you saw this on the stand at the show and you see that it has four additional holes in the air cap, and you go home and you drill those four holes in a conventional air cap of your own ----
    A. Yes.
    Q. -- and you stick it on the front of a conventional gun with a cruciform blocking plate, and in doing that you would be working the invention of the patent, would you not?
    A. Yes, I would be.
    Q. Even if you had not noticed that the holes were angled away from the centre, if you drilled them straight, you would be doing exactly what you say the Earlex product does with its holes which are straight along the axis?
    A. That is correct.
    Q. So your conclusions in relation to the model you produced after seeing the show would be the same as your conclusions are with respect to the Earlex product?
    A. That is correct.
    Q. You would assume, if you had made this model, that the air would flow out of the holes in the air cap when the horns were in the diagonal position, just as it flows through the holes in the horns when they are in the horizontal or vertical position?
    A. You would find that out if you had modified the cap at home, yes.
  116. Those questions and answers were intended to show that either the patent was not infringed by the Earlex device, or was obvious in the light of the disclosure at the Show. I have held independently that the Earlex device, with holes drilled parallel to the axis, is not an infringement. If I am wrong about that, then this evidence of Mr Bate shows, in my judgment, that the invention was indeed obvious. However Mr Bate did not support the inventiveness of arranging the holes so as not to interfere with the paint spray. His evidence was as follows:
  117. Q. In fact, if you had been on the stand at the Home Center Show and had seen this gun operating in the way I have described, it would have been immediately apparent to you having seen that what the holes in the air cap were for?
    A. Not if I had seen the gun being operated. If had operated it myself, I would have been aware what they were doing but not if I had just seen it.
    Q. And if you had operated it yourself and had been aware of what they were doing, you could have gone home easily that evening and recreated the gun in your shed using a conventional gun?
    A. Yes, that is correct. Something I also said in my report that having read the patent I could have done exactly the same thing.
    Q. You knew of the potential problem of back pressure in turbine bleed in the HVLPs?
    A. Yes.
    Q. And with the realisation that you have explained you would know that the holes in the air cap would relieve back pressure?
    A. If I was a person skilled in the art, then, yes, I would do.
    Q. In fact, when you were using it on the stand you might even be conscious that there was no whining of the motor when the horns were put in the diagonal position as they might be with conventional devices.
    A. That is true, my Lord, yes.
    Q. I think consistent with your evidence as to your reaction when you first saw the Wagner patent, if you first saw this product being used but without knowledge of the Wagner patent, you would be impressed because of what you perceive to be a simple and elegant solution?
    A. Yes.
    Q. If it was necessary you could make any routine adjustments that might be required in accordance with any of the claims of the patent, once you had arrived at the basic design, the adjustments could be made to fall within any of the claims of the patent in a routine way?
    A. Yes, that is possible, my Lord.
  118. Having installed the venting holes, I am in no doubt that the skilled person would have been able to make, and would have made adjustments by a simple process of trial and error so as to avoid interference of the venting air with the paint spray.
  119. Mr Davis submitted that all this involved too many steps, and that it was akin to a research programme. I do not think that is a fair criticism in the light of Mr Bate's very frank evidence. The skilled person would be interested in the function of the holes, which represented a departure from the standard air cap, and would be able to establish their function without any exercise of inventiveness.
  120. Accordingly, I am of the view that the invention of both claims 1 and 13 is obvious in the light of the disclosure at the Show.
  121. Documentary prior art

  122. In the light of my findings in relation to infringement, added matter and obviousness over the disclosure at the Show, it is not necessary to consider the attacks based on documentary prior art.
  123. Conclusions

  124. The patent is not infringed by the Earlex device in Original or Modified form. It is also invalid for added matter and for obviousness over the prior disclosure at the Home Center Show in Chicago in March 1991.

BAILII: Copyright Policy | Disclaimers | Privacy Policy | Feedback | Donate to BAILII