Case No: HC 03 C 01671
Neutral Citation Number: [2004] EWHC 474 (Ch)
IN THE HIGH COURT OF JUSTICE
CHANCERY DIVISION

Royal Courts of Justice
Strand, London, WC2A 2LL

Date: 17 March 2004
B e f o r e :

THE HONOURABLE MR JUSTICE LADDIE
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	RUSSELL FINEX LIMITED
	Claimant	
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	TELSONIC AG 
(a company existing under the laws of Switzerland)	Defendant	

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Mr Martin Howe QC and Mr James Abrahams (instructed by DLA for the Claimant)
Mr Christopher Floyd QC and Mr Adrian Speck (instructed by Taylor Wessing for the Defendant)

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Hearing dates: 3-4 March, 2003

Judgment
Mr Justice Laddie: 
Introduction 
1.	This is an action for declarations of non-infringement of a patent. It is brought by Russell Finex Limited. The defendant, Telsonic AG, is proprietor of patent EP (UK) 0652810 entitled “Process and device for sifting, sorting, screening, filtering and sizing substances”.
The description of the invention
2.	The patent is particularly concerned with devices for sifting and filtering which incorporate a perforated screen attached to a source of ultrasonic vibration, that is to say vibrations at such a high frequency that they cannot be heard. As the defendant’s expert, Mr. Hill, explained in his first expert report, the way in which the ultrasonic vibrations assist the screen to filter the material put on it is not unlike the action of tapping a culinary sieve in order to sift flour more effectively. The patent in suit is not the first example of the use of ultrasonic vibration to assist in sifting and filtering. It refers in its opening passages to certain prior art, including prior art made and distributed by the claimant. 
3.	The general nature of the devices used in the invention can be understood by reference to the example illustrated in Figures 1 and 2 of the patent which, shorn of irrelevant markings, are as follows:

4.	These illustrate a generator of ultrasonic waves, called an ultrasonic transducer (10), which is connected to a diaphragm resonator (14) which, in turn, is connected to a number of what are called bending wave rod resonators (16). Over the latter is mounted a screen (18) on which the material to be sifted will be placed. The screen (18) is clamped in an annular frame (20). The ends of the rod resonators (16) are spaced a little bit away from the inner face of the annular frame (20). The purpose of this is to “decouple” the ultrasonic vibration device from the frame (20). This means that all of the energy which goes into generating the vibrations and which will be used to help in sifting is imparted to the screen (18) and virtually none of it reaches and is “lost” into the frame (20). On Figure 2, the line (22) illustrates the longitudinal vibration of the ultrasonic transducer (10) and its attached diaphragm resonator (14). In other words, these items vibrate in a direction up and down the page. This imparts vibration to the rod resonators (16). These vibrations are depicted in Figure 2 by the lines (24) and (26). These vibrations are also in the up and down direction with the result that they are at right angles to the length of the rod resonators (16). The latter are bent by the effect of the vibrations which are, therefore, called bending vibrations. It is for this reason that parts (16) are called bending wave rod resonators.
5.	To work well, the whole device and, in particular, the rod resonators (16) have to be tuned to each other so that maximum energy from the vibrations is transferred to the screen (18). As the patent explains:
“Thus a plurality of coupled vibratory systems are provided, tuned to one another, which vibrate with one another at the same frequency. The diameter d of the membrane resonator 14 and the length a of the rod resonators 16 are of considerable importance, and must be tuned to the operating frequency.” (para. 34)
6.	This type of device is designed so that the screen (18) is set into undamped vibratory motion over its entire area. This is explained further in the patent:
“As the resonator rods are energised at their natural resonance, the amplitude at each node of movement is always identical, independently on (sic) length and load. By means of this method of using a plurality of resonator rods, it is possible to alter the sound density and the sound homogeneity on the screen structure at will.” (para. 13)
7.	The patentee explains that his invention is secured by the use of a plurality of resonator rods:
“The use of a plurality of resonator rods which are energised in the bending mode by a single sound transducer, makes it possible that no sound dead spots occur on the screen structure. Thus the object which the inventor sets himself is achieved in an elegant way. The resonator rods can have various shapes. They may be curved, circular or simply straight. Their cross-section is selected on the basis of physical laws which enable energisation of the desired bending vibrations in a preferred direction. They can consist of solid material or of a hollow profile. For reasons of weight, a hollow profile is preferred.” (para. 16)
8.	Further examples of devices employing a plurality of resonator rods are described and illustrated in the patent. There are a considerable number of them. For present purposes its is sufficient to refer to some only. The first is illustrated in Figures 4 and 5:

9.	This device is essentially the same as that depicted in Figures 1 and 2. However here the rod resonators are identified as (44).
10.	Another example is illustrated in Figure 6 of the patent. This has a rectangular screen (18). The transducer (10) is connected to a radial rod (46). From this project a number of transverse rods (48). The radial rod (46) and the transverse rods (48) are the rod resonators.

11.	The only other example of a multiple rod resonator device which needs to be considered at this stage is that illustrated in Figure 21:

12.	This is described in paragraph 44 of the patent. The screen (18) is not illustrated. The rod resonators are identified as (16k) and are described as being “roughly segmental in shape”. It will be seen that each is curved and in the shape of part of a circle. The items identified as (50a) are decoupling sheets, designed to connect the rod resonators (16k) to the frame (20) but without conducting significant amounts of the ultrasonic vibration to the latter. 
13.	All of the rest of the designs illustrated and described in the patent show alternative versions of multiple rod resonator designs save for one. That is illustrated in Figure 22:

14.	The description of this is brief:
“The resonator head 67 of Figure 22 carries a circular rod 68 eccentrically within the frame 20 at (sic) the decoupling sheets 50a.” (para. 45)
15.	The only other passage in the specification which can relate to this design immediately follows the text set out in paragraph 7 above:
“Thus, according to one aspect of the invention at least one concentric annular rod resonator can extend in the circular frame, and is connected to said frame by radial coupling sheets. In this case the ultrasonic inducer is attached eccentrically.” (para. 17)
The claims
16.	Although there are a number of claims, only claim 1 needs to be considered for the purpose of deciding the issue of non-infringement. It is in the following terms:
“Device for screening, grading, sifting, filtering or sorting dry solid substances or solid substances in liquids, comprising a screening surface provided in a screen frame and an ultrasonic transducer associated therewith by means of which vibrations can be transmitted to the screening surface, characterised in that at least one resonator (14) adjacent to the screening surface (18) is associated with the ultrasonic transducer (10), is tuned to the resonance of the ultrasonic transducer and can be vibrated by the latter, in particular with bending vibrations, and that the resonator has rod-type resonators (16; 16k; 44; 48:46) or at least one circular rod (68).”(emphasis added)
17.	The dispute before me is concerned with the meaning and effect of the italicised words in the claim. Mr Martin Howe QC, who appears for the claimant, says, and Mr Christopher Floyd QC for the defendant does not dispute, that, as a matter of language these words mean that where the resonator is circular, only one is necessary (although more can be used). On the other hand, when rod-type resonators are used, there must always be more than one. 
The Claimant’s designs which are said not to infringe
18.	The claimant is entitled to operate outside the ambit of the patent. To that end it sought confirmation from the defendant that a number of proposed designs did not infringe. Five such designs were put forward. For present purposes the first three are to be considered as indistinguishable. Thus confirmation was sought, in effect, in relation to the following three designs:

19.	For ease of reference, the first of these will be referred to as the Single Straight Rod design, the second as the Single Bent Rod design and the third as the Spiral design.
20.	Before the action commenced, the defendant accepted that the Single Straight Rod design did not infringe. This is not surprising since it consists of a single resonator which is clearly not circular. On the other hand, no such confirmation was given in respect of the other two designs. The defendant’s position is that the Spiral design is a literal infringement of claim 1. Even if this is not correct, it argues that both the Single Bent Rod and the Spiral are within the claim when purposively construed. Before considering the arguments relating to these two designs, there are two preliminary matters which can be disposed of. 
The effect of numerals in the claim
21.	It will be seen that Claim 1 cross-refers by the use of numerals to the specific embodiments described and illustrated in the patent. Mr Floyd argues that it is not legitimate to use claim reference numerals so as to confine the scope of a claim to a specific embodiment. He says that they are only an indication of what is covered by a claim. In effect, he argues that it is impermissible to take into account the reference numerals if doing so has the effect of limiting the scope of protection or of supporting a limited construction. Their function is not to limit an integer to the specific thing identified by the reference numeral so as to exclude everything else from its scope. In support of this, he refers to Rule 29(7) of the Implementing Regulations of the EPC which provides:
“If the European Patent application contains drawings, the technical features mentioned in the claims shall preferably, if the intelligibility of the claim can thereby be increased, be followed by reference signs relating to these features and placed between parentheses. These reference signs shall not be construed as limiting the claim.”
22.	He accepts that the UK Act and rules contain no express equivalent of these provisions, but he says that the same approach to construction must be adopted here. He points out that s 125(1), which requires the extent of protection to be determined by the claims, is one of the sections which, by s 130(7), is intended to have, so far as practicable, the same effect as the corresponding provisions of the EPC. Since the corresponding provision of the EPC, namely Article 69, has to be read subject to Rule 29(7), so must s 125. He also relies on Philips Electronics’ Patent [1987] RPC 244. 
23.	Mr Howe does not dispute the generality of this argument. He accepts that since claims in European patents are drafted in accordance with a convention which includes rule 29(7), they ought to be construed in accordance with the same convention when they come to be enforced in national courts. However he takes issue with Mr Floyd insofar as he tries to push the provisions of rule 29(7) to the extent of prohibiting the use of the reference numerals in a claim to reinforce a narrower view of the scope of protection than that argued for by the patentee. 
24.	Rule 29(7) can be considered to be in two parts. The first part encourages the use of reference numerals in cases where to do so will increase the intelligibility of the claim. Their purpose is therefore to add information to the claim which will make it easier to understand what the patentee is claiming as his monopoly. Even without this rule, it is well established that the claims must be read in the context of the specifications. The rule reinforces this. 
25.	However, just as it is not permissible to take stray phrases from the specification to expand or contract the scope of the claims, so too the reference numerals should not be used for that purpose. That is the effect of the second part of the rule. Mr Howe gave a good illustration of this in the course of argument. A claim may refer to two parts of a device being joined at a particular location and use a numeral to indicate where in the figures such a join is illustrated. The figure shows the use of a nut and bolt. It would not be legitimate to construe the claim as limited to the use of this particular method of joinder. 
26.	Reference numerals therefore are designed to be, and can be, useful tools to elucidate the inventor’s intention. As such they may, depending on the circumstances, help to illustrate that the inventor intended a wide or narrow scope for his claim. On the other hand they cannot be used to import into the claim restrictions which are not foreshadowed by the language of the claim itself.
The prosecution history of the patent
27.	The second preliminary point relates to the use of the prosecution history of the patent as an aid to construction. Part of Mr Howe’s argument consists of an analysis of the course of events in the European Patent Office which led to the inclusion of the relevant words at the end of claim 1 by amendment. The circumstances in which those amendments arose showed, so he argues, that it was impermissible for the defendant to advance the construction of claim 1 which it does now. This approach is sometimes referred to as file wrapper estoppel. Mr Floyd argues that file wrapper estoppel is not part of our law. It is illegitimate to refer to the prosecution history as an aid to construction.
28.	Mr Howe and Mr Floyd agree that there is no binding authority on this issue in English jurisprudence. In Bristol Myers Squibb v Baker Norton [1999] RPC 253 at 274-275, Jacob J pointed out the problems which would arise were file wrapper estoppel part of our law. Mr Howe argues that in Rohm & Haas v Collag [2002] FSR 445 at 456-8 the Court of Appeal appears to have expressed support for file wrapper estoppel. He accepts that, even if it did, its views were obiter. Mr Floyd points out that in Rohm & Haas, the court was not concerned with the question of amended claims but rather with only with the narrow point of whether a letter explicitly referred to on the cover of the specification but not forming part of it could be referred to, if necessary, to resolve an issue as to construction. He says that I should have no regard to the prosecution history in this case.
29.	File wrapper estoppel is a highly contentious issue at the moment. There are current discussions as to whether it should be allowed in this country and whether there should be legislation expressly to that effect. If it is, there is a real prospect that we will experience all the difficulties which the USA has experienced in trying to implement it. In many cases it is likely that allowing such a doctrine here will add considerably to the cost and complexity of litigation while producing little in the way of benefit to the parties. In some cases file wrapper estoppel would add obscurity to the meaning of the patent. 
30.	In the absence of binding authority or legislation, I would be reluctant to accept that this doctrine has any part to play in construing a patent and its claims. Patents and their claims are meant to be statement made by the patentee to the relevant public. Their meaning and effect should be discernible from the face of the document. However, for reasons set out below, I do not think it necessary to resolve this issue in this case. The meaning of the claim appears to me to be clear enough without resort to this material. In the result I have not looked at any of the prosecution history of the patent. I will treat the claims as if they had always been in their current form. I have paid no attention to what Mr Howe says is the reason for the amendments made. I have not read any of the documents relating to this issue.
Construction of the claims
(i) The Spiral Design and literal construction of the claim.
31.	It is convenient first to consider what might be called Mr Floyd’s direct argument of infringement directed to the defendant’s Spiral design. He says it is not necessary to consider purposive construction and the guidance given in cases such as Catnic v Hill & Smith [1982] RPC 242 and Improver Corp v Remington Consumer Products Ltd [1990] FSR 181.  The Spiral design clearly falls within the scope of claim 1. He says there is literal infringement.
32.	Although expert evidence was served by both sides, neither counsel nor experts suggest that there are any words in the claims which need technical explanation. In particular all the words used in the crucial last few words of claim 1 are used in the ordinary way. There is no dispute between the parties that the Spiral design incorporates a single resonator. Because of this it does not fall within the words “rod-type resonators” in Claim 1. If there is infringement (without regard to questions of purposive construction) it must be because the Spiral design contains “at least one circular rod”.
33.	Circular is defined in the Shorter Oxford English Dictionary as “of the form of a circle; round in superficies”. Chambers Twentieth Century Dictionary defines the word as meaning “of or pertaining to a circle: in the form of a circle: round: ending in itself: recurring in a cycle; addressed to a circle of persons”. A circle is a closed shape having no beginning or end. It is an endless loop. A spiral is not a circle nor is it circular. 
34.	However Mr Floyd argues that the use of the word “circular” does not restrict the claim to resonators which are whole perfect circles. He says that a slightly squashed circle would fall within the literal meaning of the claim. From this he argues that spirals have enough in their make up and curvature – in particular having a radius of curvature – properly to be considered circular. 
35.	Whether or not a slightly squashed circle would fall within the claim is likely to depend upon how slight is the deformation. It is not necessary to consider that in this case. However I do not accept Mr Floyd’s submission insofar as it relates to spirals. If something has a radius of curvature it is curved. But not all things that are curved are circular. Although a spiral incorporates curves, it is not a circle or circular. It is not an endless loop. Furthermore, Mr Floyd’s construction is not consistent with the way in which the words circular and curved are used in the specification. 
36.	As explained above, the majority of the specification is concerned with the use of devices containing a plurality of rod-type resonators. They are illustrated as being rod-like, in the sense of having much greater length than width and having at least one free end. As the specification explains they can be “curved, circular or simply straight” – a use of language which is consistent with curved and circular meaning two different things. It is particularly noticeable that the description of the device depicted in Figure 21 (see paragraph 11 above) includes the following:
“… three rod resonators 16k projecting from the centre Z, and being roughly segmental in shape, which, with a curvature in the same direction, are applied close to their free ends to thin and if necessary radially extending decoupling sheets 50a”
37.	As illustrated, each of these resonators is in the shape of part of a circle yet they are not referred to as circular. They are said to possess curvature. These are also cross referred to in the claim as examples of the rod-type resonators, not as examples of the circular type. Furthermore, the fact that the word “circular” in the patent is used in its normal sense is reinforced not only by the fact that its use in the claim is cross-referenced to item (68), that is to say the resonator depicted in Figure 22, but this is also consistent with the other relevant passage in the specification, namely paragraph 17 (set out at paragraph 15 above) which refers to an “annular” rod resonator.
38.	For the sake of completeness, I should mention two other groups of devices illustrated in the patent. First, Figures 18 and 19 illustrate two devices incorporating perforated plates (58):
        
39.	Figure 18 is said to show the perforated head above a resonator head (64) with radial rod resonators (16). On the other hand Figure 19 illustrates an alternative design described as being “without resonators”. How that falls within the claims of the patent is not clear. It may be an embodiment which has been stranded by amendments to the claim. Whatever its origin, it throws no light on the matter of how the word “circular” is used in the patent. 
40.	The other devices are depicted in Figures 16 and 17
              
41.	Both of these are said to depict perforated plates (58).  These are said to employ radial fins (59) and “annular or curved fins 60 connecting the former”. Presumably Figure 16 depicts annular fins and both Figures depict curved fins. Whether those fins have any material affect on the transmission of ultrasonic vibrations is not stated in the patent, so it is not clear whether, from a vibration point of view, they are invisible. In any case, none of this detracts from the view that the word “circular” is used in its dictionary sense in the specification. The argument of literal infringement fails.
42.	This takes me to the defendant’s alternative case. Even if the Spiral and Single Bent Rod designs do not fall within the literal wording of the claim, they fall within it when construed purposively. 
(ii) The Spiral Design and purposive construction of the claim.
43.	In relation to this part of the argument, the parties have referred to all the familiar recent cases on construction and, in particular, Improver. It is easy to slip into thinking that one always has to follow the Improver formula in order to determine whether there is infringement. However Improver is no more than an aid to construction. It is not a straightjacket. As the Court of Appeal said in Pharmacia v Merck [2002] RPC 775, it is a normally useful tool. In some cases the Improver questions are difficult to apply. If so, the court should not struggle to shoehorn the questions into use. After all, all of our continental colleagues have to carry out the same exercise of construing patents as we do in accordance with the same law and the same Protocol on Construction. They seem to be able to do it without the structured Improver  approach. These issues were considered by me in Merck & Co Inc v Generics (UK) Ltd [2003] EWHC 2842 (Pat). I only repeat two paragraphs in that judgment:
“48.	It seems to me that what the Protocol requires is that the monopoly should cover all embodiments, whether explicitly mentioned in the claims or not, which the notional skilled reader would conclude, with reasonable confidence, the inventor wanted to cover. Where it is clear that the patentee did not intend to obtain protection for particular variants, it is not open to the court to extend the monopoly to cover them. Similarly, if a notional skilled addressee cannot conclude with reasonable confidence that the inventor wanted to obtain protection for a particular embodiment, it must follow that the patent conveys the message that the patentee might well have intended to exclude that embodiment. To give protection in such circumstances would run the risk of going against the intention of the patentee, thereby being unfair to him, and would not be giving third parties a reasonable degree of certainty as required by the Protocol.
49.	Determining whether a skilled reader would conclude with reasonable confidence that a particular embodiment was one the patentee wanted to cover involves assessing all the facts of the case. The wording of the claims is the most important one, but is not necessarily determinative. Matters such as the way the inventor describes his inventive contribution and his explanation, if any, of how the invention achieves its claimed results are matters to be taken into account. The factors, and how they interrelate to each other, will vary from case to case.”
44.	Although Mr Howe argues that it is neither necessary nor appropriate to use the Improver structured approach, I think it is convenient to start with it.
45.	 The first question is whether the use of the Spiral resonator has a material effect on the way the invention works. As was pointed out by Hoffmann J in Improver, the answer to this question depends upon the level of generality at which one describes the way the invention works. Mr Howe argues that the invention in this question must mean the invention as claimed. Mr Floyd suggest that this approach is circular. If one is restricted to an invention which uses all the stated parameters of the claim, it is almost inevitable that there will be differences between it and the variant which is being considered. One must break away from the strict wording of the claim and look to the underlying inventive concept.
46.	In my view the level of generality is that indicated by the inventor. Here he has described what he hopes to achieve by use of his invention:
“9.	Resonators are to be so designed that the screen is set into undamped vibratory motion over its entire area. 
10.	The teaching of the independent patent claims, lead to the solution of this object. The sub-claims indicate more extensive developments.”
47.	At this level of generality, it is clear that the Spiral design works in essentially the same way as both the rod-type resonators (because it is one) and the circular resonator. This is because, as Mr Hill explained, it does not matter whether there is one resonator or multiple resonators nor what their shape is. All of them can be made to work. Indeed, as he confirmed under cross-examination, the Single Straight Rod resonator, which the defendant concedes is not an infringement, also works in the substantially the same way to produce the same result. The answer to the first Improver question is in the negative. 
48.	The second question is whether it would have been obvious to a man skilled in the art that the Spiral design would work in the same way? At the same level of generality as is used for the first question, the answer is in the affirmative. Anyone in this art would know that any shape and any number of resonators could be made to perform the necessary function. 
49.	Having got this far, as is to be expected, the defendant employs the familiar pleas that if the claimant is allowed to use the Spiral design it will be taking all the benefits of the invention. That the design may work slightly better than others covered expressly by the claims (as is alleged here by the claimant) is nothing to the point. That is merely adding ingenuity to robbery.
50.	The third Improver question is; would the skilled reader nevertheless have understood that the patentee intended to confine his claim to the primary meaning of the claim? As I explained in Merck v Generics, this question is expressed the wrong way round:
“57.	… if one is adopting the structured approach, it is only Improver question (3) which needs to be answered. However, it appears to me that there is one respect in which that question needs to be approached with caution. In formulating the questions, Hoffmann J said he was applying the guidance in Catnic. There is no doubt that the binding authority on construction in this jurisdiction is the latter case. That was confirmed by the Court of Appeal in Kastner v Rizla [1995] RPC 585. Yet there appears to be a potential difference between the way the issue of construction was put in Catnic to the way it is explained in Improver. Imagine the case where the notional skilled reader does not understand why the patentee put a limitation in the claim. According to Catnic, in such a case the limitation is effective because it is not “apparent” that the limitations “cannot have been intended by the patentee”. The variants will be excluded from the monopoly. By contrast the same facts would be answered differently if Improver question (3) is applied rigidly. Where the reason for introducing the limitation is unclear, the skilled reader could not say that he understood “that the patentee intended to confine his claim”. Thus Improver question (3) would be answered in the negative and the claim will be construed to include the variants. I think that this difference is more imagined than real. At p. 197 of Improver it appears to have been accepted that if the notional skilled addressee would speculate that the patentee had good reason for including the limitation in the claims, the limitation is effective. In other words the Catnic approach was adopted.”
51.	So, the question is, would it have been apparent to the skilled addressee that, when the claim refers to “at least one circular rod”, a limitation to rods which are circular could not have been intended by the patentee? When asked that way, there can only be one answer. As indicated above, every shape and any number of resonators could be made to work. That would be known to everyone. The patentee has given no explanation in the patent as to why he required there to be at least 2 rod-type resonators when, presumably, he knew there was no technical reason for this limitation. Similarly he has given no explanation why he would only allow the use of a singular circular resonator, even though, presumably, he knew that there was no technical reason why not only would single rod-type resonators work, but so too would, say, square, rectangular, triangular or hexagonal ones. From a technical point of view, the limitations in the claim appear to be arbitrary and tied to the examples illustrated in the specification. 
52.	The way in which Mr Floyd puts his client’s argument in his skeleton argument is illuminating:
“The purpose of the inventor was to achieve good distribution across the mesh. That is achieved by extending conductors of bending vibrations in both dimensions. We ask forensically would the skilled person think that a distorted circle would be excluded? Or one with a small segment missing? Or one where a length of rod is formed into a circle with overlapping ends? Or a coil? As in Catnic the Patent is addressed to a person skilled in the art, not to a geometry student.  The spirals are no different.  To exclude these simple variants would allow others to take all the benefit of the invention without infringing, and could not be right.”
53.	Exactly the same questions could be asked, and the same jury plea could be made, in respect of all excluded designs. Mr Floyd’s argument, if accepted, would be to remove all effect from the critical words at the end of claim 1. This is not purposive construction. It is redrafting.
54.	As Mr Howe reminds me, in STEP v Emson [1993] RPC 513, Hoffman LJ said:
“The well known principle that patent claims are given a purposive construction does not mean that an integer can be treated as struck out if it does not appear to make any difference to the inventive concept. It may have some other purpose buried in the prior art and even if this is not discernible, the patentee may have had some reason of his own for introducing it.” ( p 522).
55.	That applies here. The skilled reader would not know why the inventor limited his claim as he did. Therefore he would be unable to decide that the limitation could not have been intended by the patentee. In my view, the Spiral design does not infringe claim 1.
(iii) The Single Bent Rod design and purposive construction of the claim
56.	The defendant accepts that Single Bent Rod design does not fall within claim 1 on a strict literal or acontextual interpretation. This is because this design is not in any sense circular (although it does have a curve at the bend) and it does not fall within the expression “rod-type resonators”. The latter involves the use of at least two resonators. The defendant accepts that the Single Bent Rod design acts as a single resonator. On the other hand it says that because of the way vibrations are reflected at sharp bends, were the resonator to have been made with a sharp “V”, this would function as two resonators and would have fallen within the claim. 
57.	The first two Improver questions are answered as set out above. The question of infringement therefore turns on the third question. Mr Floyd argues that the skilled addressee would appreciate that the Single Bent Rod resonator spreads the ultrasonic vibration across the surface of the sifting screen. This is the purpose of the invention. He asks, why should any sensible patentee wish to exclude this simple design when all the designs illustrated in the patent together with the sharp “V” design would be included? The invention is not concerned with the precise waveform in each limb. It is concerned with transmitting the vibration to the screen.  
58.	The trouble with this argument, as with the argument relating to the Spiral design, is that it has no boundary. If all that matters is whether the design will work, the exclusions at the end of the claim are not simply meaningless, they are positively misleading. Indeed the approach adopted by Mr Floyd would mean a single straight rod resonator would fall within the claim. He accepted as much in the course of his submissions. A single rod, such as the defendant’s Single Straight Rod design, would work just as well as any other – as the defendant’s expert agreed – and Mr Floyd concedes that it could be regarded as indistinguishable from two rods connected together at 180o to each other. One is driven to ask, why the inventor put any limitations at the end of the claim. To that there is no stated or obvious answer. One can only speculate. Perhaps it was prior art. Perhaps it was a mistake.  In the circumstances, to adopt the approach in Catnic, it would not be apparent to the skilled addressee that the limitations “cannot have been intended by the patentee”. Both from the claims and the specification it is apparent that limitations were intended. Alternatively, to use the approach suggested in Merck v Generics, the addressee could not conclude with reasonable confidence that the Single Bent Rod design was one the patentee wanted to cover. 
59.	As with the Spiral design, the claimant is entitled to a declaration of non-infringement.