T 0473/98 (Magnetic field screen) 05-09-2000

Reasons for the decision

1. The proprietor's appeal is admissible.

2. Admissibility of the opponent's appeal

2.1 The formula of the decision under appeal is expressed on EPO Form 2331 as: "European patent No. 0216590 is revoked" and the heading provided on this form to indicate a possible "additional decision" is crossed out.

2.2 Hence the decision revoked the patent in its entirety, ie did not revoke it partially by maintaining it in amended form by interlocutory decision appealable separately pursuant to Article 106(3) EPC. Independently of the reasons for the decision, the patent was therefore deemed not to have had the effects specified in Article 64 EPC (cf Article 68 EPC). In this sense the decision was fully consistent with the request of the opponent in the opposition procedure that the patent be revoked in its entirety. He was therefore not adversely affected by the decision within the meaning of Article 107 EPC, first sentence, as interpreted, eg by decision J 12/85, Inadmissible appeal/Kureha (OJ EPO 1986, 155), and is accordingly not a party who may appeal under that provision.

2.3 The fact that the patent was opposed in the notice of opposition "in vollem Umfang" (in its entirety), meaning that all claims were opposed, does not, according to the established jurisprudence and practice of the EPO, mean that the opponent's request is for a decision that no claim of the patent meets the requirements of the EPC. It means rather that the request is that the patent should not be maintained even in amended form by deletion of some claims - a request which was fully complied with by the decision under appeal.

2.4 The board agrees with the opponent's contention that the opposition division should not have purported to decide - in the strict sense - that certain priorities were correctly claimed and that the subject-matter of claim 14 was new and inventive when these matters were not necessary for the conclusion that the subject-matter of claim 3 lacked novelty, which was the ratio decidendi founding the formula of the decision under appeal. The board, however, regards this as an error of expression rather than a substantial procedural violation. It was entirely appropriate and desirable in the interests of overall procedural efficiency and effectiveness that an opposition division should include in its decision, by way of obiter dicta, reasoned findings which could obviate a remittal in the event of a revocation flowing from a certain ratio being reversed on appeal. The mere fact that in the present case such findings were somewhat misleadingly referred to in the pronouncement as "further decisions" "included" in the decision proper did not, in the judgment of the board, constitute a substantial procedural violation. As indicated above (2.1) the decision formula makes it abundantly clear in the present case that no "additional decisions" were in fact made, and equally clear what findings and reasons therefor constituted the ratio; those findings which the opponent rightly objects to being described as decisions could not be ratio since they manifestly do not support the formula.

In particular the decision formula makes it indisputably clear that the decision under appeal was not an interlocutory decision maintaining the patent in amended form pursuant to Article 102(3) EPC.

2.5 In this context the board observes that the finding of the opposition division in relation to the novelty of the amended claim 1 was by no means supererogatory as implied in the opponent's submission. In the present case the reference in claim 3 to claim 1 causes the amendments to claim 1 to have a knock-on effect on claim 3 and the novelty of the subject-matter of claim 1 is at least arguably inheritable by claim 3 via this link in such a way that findings in relation to these matters were indeed necessary for the conclusion and hence are ratio.

2.6 The board also observes that a corollary of the opponent not being adversely affected by the revocation is that, contrary to the opponent's submission, the proprietor is not protected against a reformatio in peius. Decision G 9/92, Non-appealing party/BMW (OJ EPO 1994, 875), applies only to interlocutory decisions maintaining a patent in amended form, which may adversely affect both proprietor and opponent. Accordingly the opponent in his capacity as a party to the appeal proceedings as of right pursuant to Article 107 EPC, second sentence is not restricted in his requests or arguments in any way by his non-appellant status.

2.7 Since, for the reasons given above, the opponent was not adversely affected by the decision under appeal the opponent's appeal does not meet the requirement of Article 107 EPC, first sentence, for an admissible appeal.

2.8 Accordingly the opponent's submissions will be treated hereinafter as those of respondent in the admissible appeal of the proprietor.

3. Amendments - Article 123(2) and (3) EPC

In the judgment of the board the amendments are permissible under Article 123(2) and (3) EPC for the reasons given in the decision under appeal. The opponent's submissions on this point in the statement of grounds of appeal essentially repeat what was argued in the opposition procedure and the board has nothing to add to the opposition division's considerations and conclusions on this point.

4. Article 100(b) EPC

4.1 In effect the opponent's contention is that the disclosure and the scope of claim 1 are not commensurate. The board is not persuaded by either prong of this argument. The teaching of claim 1 involves an approach to the design of a screening coil which is radically different from prior art approaches and is therefore claimed in a way which appropriately reflects this difference. On the other hand the manner in which this design approach can be implemented is set out and developed in a systematic pedagogic fashion in the description, starting with the example of screening an infinite straight current-carrying wire and progressing to the screening of saddle coils producing a gradient field.

4.2 Neither does the board accept the opponent's characterisation of claim 1 as claiming all ways of achieving a result. The result is a substantially zero external field but the claim is explicitly directed to a specific method of achieving that result.

5. Claim 1

5.1 Novelty

5.1.1 The opponent's argument that the amendment by insertion of the phrase "for NMR imaging apparatus" does not restrict the claim was, in the judgment of the board, refuted in the oral proceedings before the opposition division (points 7 and 8 of the minutes) where it was pointed out that suitability for the NMR imaging application requires access to an imaging volume. The essentially two-dimensional ("endless Z' axis") screening approach taught for particle accelerator quadrupole magnet screening in E1 would therefore not be suitable for NMR imaging and could not destroy novelty. Making the assumption in favour of the opponent that the person skilled in the art would know how to deal with end-effect problems would still not mean that there was even an implicit actual disclosure of a coil design method suitable for NMR imaging.

5.1.2 Neither is the board convinced by the opponent's further argument that the current distribution on the surfaces of the coaxial right circular cylinders in the example at column 4, lines 39 ff, of E1 must be the same as that specified by the method of claim 1 since they both achieve the same zero external field. Apart from the fact that this argument ignores the fact that this example is a two-dimensional geometry not suitable for NMR imaging, the board observes that the claim does not claim the result achieved but the method of achieving it, ie the method of arriving at the current distribution, so that even if the assumption is made in favour of the opponent - although he has not discharged the onus of proving this to be the case even for a particular geometry - that at least in the ideal or mathematical limit the current distributions were the same, the method of claim 1 would still be new, since the physical design steps, ie the positioning of wires and the dimensioning of currents, by which the approach to the ideal theoretical current distribution proceeds, are different, being based on mathematically distinct calculation methods. This is not a case of granting a patent for a new and ingenious way of describing a known process, it is rather a case of denying the proposition that identity of stated goal implies identity of path theretoward.

5.1.3 For the avoidance of a possible misunderstanding of the board's position, it should be emphasised that although the hypothetical superconductive surface is by definition not a tangible feature of the method it is a legitimate way of defining the design algorithm which leads to physical design steps of selection of wire position and current magnitudes and magnetic field, just as, eg a notional mirror plane may be used to describe the location of an array of tangible objects.

5.1.4 Accordingly the board concludes that the subject-matter of claim 1 is novel over E1. The opponent has not adduced any arguments alleging lack of novelty of the subject-matter of claim 1 over any other document.

5.2 Inventive step

5.2.1 The decision under appeal does not include a finding as to whether the subject-matter of claim 1 is to be considered as involving an inventive step within the meaning of Article 56 EPC. Neither has the opponent addressed the issue in his submissions in the appeal procedure and, since he was not represented at the oral proceedings before the board, it was not possible to invite him to make good this omission on that occasion. Having regard to the technical facts in the present case (see 5.2.2 below), the board does not see this as a reason to remit the case to the department of first instance - a view which is reinforced by the consideration that the opposed patent has been pending at the EPO since 1986. Nor has the opponent requested such remittal. Accordingly the board will decide this issue, exercising the power vested in it by Article 111(1) EPC, second sentence.

5.2.2 In the present case, the finding by the opposition division at point 3 of the decision under appeal, when dealing with novelty, that:

"None of the cited pertinent documents to be considered ...under Article 54(2) EPC, namely documents E1 to E11 and K2 discloses, in the context of a method of designing a screening coil for NMR imaging apparatus, the step of calculating the induced current distribution in a hypothetical continuous superconductive metal surface positioned in the place of wires of the screening coil, as contained in present claim 1."

is, in the judgment of the board, tantamount to a finding that, having regard to the prior art on file, the method of designing a resistive screening coil specified in claim 1 including the step referred to was not obvious for the person skilled in the art. The reason why the board feels able, exceptionally, to extrapolate from novelty to non-obviousness in this case is that the design approach based on a hypothetical superconductive surface is so radically different from the known approaches that it would be impossible for the prior art to suggest it without mentioning it. Even the use of a real superconductive surface amounts to teaching away from the use of a hypothetical superconductive surface which lies at the heart of the insight underlying the invention claimed in claim 1. Hence, irrespective of which of the prior art documents is taken as closest prior art in a problem and solution approach, the conclusion is that the solution of claim 1 is not derivable from that alone or in combination with any other document on file or common general knowledge in the art.

5.2.3 For completeness it should also be mentioned that although the decision under appeal refers at point 5 to the possibility that "E11 could play a role in the discussion of the existence or otherwise of an inventive step in present claim 1" as a reason for introducing E11 into the procedure, no argument based on E11 was adduced in the appeal procedure and the board does not see itself as called upon to devise such an argument on behalf of the opponent.

6. Claim 3

6.1 The board is not persuaded by the reasoning at point 6 of the decision under appeal. References are made at 6(a) to very substantial portions of the description and claims of E2 which are alleged to disclose "all the apparatus features referred to in present claim 3", but the specific features of the claim have not been read onto the disclosure of E2 in a perspicuous and convincing way. Thus claim 9 of E2 is referred to, although this claim specifies "cylinders of a superconducting material", whereas claim 3 of the opposed patent is specifically restricted to "a resistive screening coil" via its reference to claim 1.

6.2 This last point is one of the reasons why the board does not agree with the assertion at 6(b) of the decision under appeal that the method features included in claim 3 via the reference to claim 1 cannot add a restriction to the screen as such. Another way in which claim 3 inherits a restriction from claim 1 is, contrary to the finding of the opposition division, in the quality of the approximation to a substantially zero field on the side of the screen away from the electrical coil. Following the calculation step of claim 1 will result, for a given specific geometry, in specific magnitudes of currents and specific positions of conductors in the screen and, in the judgment of the board, it has not been plausibly demonstrated that the same magnitudes and positions would result from following the teaching of E2. In particular it cannot be assumed that because E2 aspires to produce a screen which "at least partly compensates for an external magnetic stray field of the first magnet" (E2, page 2, lines 9 to 10), using a completely different mathematical design rule involving the field strengths and cross-sections of the first and second coils (ibid, lines 22 to 37), that the currents and wire positions and magnetic fields in the screen thus produced would be substantially identical with those existing in a screen as specified in claim 3 of the opposed patent. On the contrary, the evidence filed by the proprietor on appeal - which has not been challenged by the opponent - shows a significantly different external field for the two screens. In the view of the board, the external magnetic field produced by the screen in use is an apparatus feature which is capable of distinguishing the claimed screen from a prior art screen and the evidence on file suggests plausibly that it does so in fact.

7. Claim 14

7.1 Novelty over D1 (Article 54(3) EPC)

Although the opponent in his submissions on appeal challenged the procedural regularity of the opposition division finding that claim 14 of the opposed patent was entitled to a priority date of 19 June 1986, he has not challenged the factual correctness of this finding and indeed relies implicitly on this finding in continuing to contend, on appeal, that D1, published on 12 August 1987 and claiming priority of 6 February 1986, destroys the novelty of the subject-matter of claim 14 by virtue of Article 54(3) EPC. This contention was refuted at point 4(a) of the decision under appeal and the board has nothing to add to this refutation.

7.2 Novelty - Article 54(2) EPC

The reason given in the decision under appeal at point 4(a)(ii) for regarding the subject-matter of claim 14 as new over all pre-published documents on file has not been challenged on appeal. Neither does the board see any reason to disagree with this finding.

7.3 Inventive step

The opponent's argument on appeal that, having regard to a combination of E2 and D2, the subject-matter of claim 14 does not involve an inventive step has also largely been refuted in the decision under appeal at point 4(b). The notion that it was an obvious desideratum to construct a two-coil screening system in such a way that the reduction of the field within the inner screen is avoided does not persuade the board in view of the fact that, as pointed out in the decision under appeal, ibid, in D2 this reduction was accepted as a given fact (D2, paragraph bridging pages 7 and 8). Further, the opponent's reference to "more than one screening coil" in the abstract of D2 is somewhat misleading. In the terminology of D2 the "first set of coils" is the set of coils producing the desired field in the working volume while the "second set of coils" is the single set of screening coils in a three-coil Maxwell configuration (D2, page 7, last paragraph). In the judgment of the board, the screening function of these three axially mutually spaced coils vis-à-vis the Maxwell triple of main field coils does not provide any suggestion in the direction of a configuration of one screening coil located inside another as specified in claim 14.

8. In the view of the board the patent, as amended in accordance with the single request, and the invention to which it relates meet the requirements of the EPC.