T 0698/18 (Resonating and matching circuit / MURATA MANUFACTURING) 05-03-2019

Reasons for the Decision

Sufficiency of disclosure (Article 83 EPC)

1. Claim 1 according to the main request and to auxiliary requests 1 to 8 relates to a wireless IC device comprising:

- a wireless IC chip,

- a radiation plate, and a

- power supply circuit board connected to the wireless IC chip and comprising a power supply circuit including a resonant circuit having a predetermined resonant frequency.

2. Claim 1 further specifies that the transmission or reception signal has a frequency substantially corresponding to the resonant frequency of the resonant circuit, wherein the resonant circuit has a function as a matching circuit for matching the impedance of the wireless IC chip with the impedance of the radiation plate.

3. Insofar as the reception signal is concerned, and in view of the fact that a reception signal may cover a large spectrum of frequencies, the Board interprets the claim's wording as implying that the claimed device is specifically adapted to process signals, or the portion of signals, corresponding to the resonating frequency of the resonant circuit.

4. It is further implicit, from the claim's wording, that the matching functionality similarly refers to the signals corresponding to the resonating frequency.

5. The application does not contain any embodiment corresponding to the claim's definition, but this alone cannot justify the refusal of the application, since

the purpose of the 'examples' evoked in Rule 27(1)(e) EPC [1973] appears primarily to be to complete an otherwise incomplete teaching" and that "the application cannot be refused under this provision if the description is considered to describe, despite the [...] lack of examples actually embodying the invention, one way of carrying out the invention (T 990/07, Headnote and point 3).

The issue to be decided is whether the application is actually sufficiently complete, despite the absence of concrete embodiments, to allow the skilled person to carry out the claimed invention.

6. The elaboration of a circuit that should not only resonate at a predetermined frequency, but also function as an impedance matching circuit is not straightforward. Paragraph [0057] of the original disclosure, which constitutes the only basis for the recited functionalities of the claimed invention, acknowledges this difficulty. It reads (emphasis in bold added by the Board):

[0057] According lo the present invention, the resonance circuit may function as a matching circuit for matching the impedance of the wireless IC chip with the impedance of the radiating plate. Alternatively, the power feeding circuit board may further include a matching circuit that includes an inductance element and a capacitance element and that is provided separately from the resonance circuit. In general, when the resonance circuit includes the function of a matching circuit, the design of the resonance circuit is complicated. However, if a matching circuit is provided separately from the resonance circuit, the resonance circuit and the matching circuit can be designed independently.

7. The elaboration of a matching circuit for matching the impedance of the wireless IC chip with the impedance of the radiation plate requires precise knowledge of both parameters. The appellant was able to provide evidence that the impedance of the IC wireless chip is well defined for the intended frequencies of use. It typically belongs to the set of technical data made available by manufacturers. It may further be assumed that the impedance of the radiating plate is known with sufficient precision. Such data may be obtained from the radiating plate specification or from measurements.

However, the precise knowledge of these two parameters does not appear to be sufficient.

8. In the absence of any information in the application as to how the invention is to be carried out, the reader can only rely on common general knowledge in the field of matching networks.

9. The appellant's view that the elaboration of a separate matching network combining capacitance and inductance elements (the second branch of the alternative referred to in paragraph [0057]) would simply result from the application of this common knowledge is not questioned by the Board. How such knowledge can effectively be used in the context of a circuit which is required to resonate at a predetermined frequency is, however, far from straightforward, contrary to what the appellant suggests.

10. As a matter of fact, the condition that the circuit must match, for a given frequency, the impedance of the wireless IC chip with the impedance of the radiation plate, appears to conflict with the additional requirement that said circuit should resonate at said frequency. The principle underlying the elaboration of matching circuits implies, in effect, that the impedance "seen" by a power source be the complex conjugate of its own impedance. Applied to the present situation, this requires that the impedance of the resonating circuit and radiation plate, in combination, and measured at the output of the wireless IC chip, be the complex conjugate of the impedance of the IC chip.

11. When applied to the elaboration of separate matching networks, as relied upon by the appellant, the application of said principle implies that the values of the capacitance and inductance to be incorporated in such a circuit are determined by equating the real and imaginary parts of the conjugate impedance of the source with the corresponding terms of the circuit it supplies.

12. While this approach is straightforward when designing a separate matching circuit for which no other constraints apply, it is not so when applied to a circuit which must resonate at a predetermined frequency. In effect, it is even doubtful whether the equations that express the condition of resonance, on the one hand, and of matching the IC chip with the resonating plate, on the other hand, always have a solution in the case of a circuit of the kind illustrated in Figure 3.

13. In the present context, the Board has no doubts that the skilled person, despite the absence of concrete values for the capacitance and inductance elements in the various circuits disclosed in the application, would be able to determine values that make the circuit resonate at a predetermined frequency. This undoubtedly applies to the circuit of Figure 3 of the published application, referred to by the appellant.

Any change that the matching requirements require would, however, directly affect the behaviour of the power driving circuit and, in particular, its resonating frequency.

14. The appellant's view that the skilled person would simply have to take advantage of the capacitance and inductance elements of the resonating circuit to realise the matching functionality is thus rejected. In effect, there is no guarantee that a matching may even be obtained within the bandwidth of the resonating circuit. For these reasons, the Board rejects the view that the difficulty in fulfilling both conditions as to matching and resonance could be solved by some trade-off between both requirements.

15. In the absence of any evidence regarding the existence and the functionalities of simulation programs, well known to the skilled person, that would indeed permit the elaboration of a circuit resonating at a certain frequency and including the function of a matching circuit at said resonance, the appellant's view that such programs would compensate for the lack of details in the description is rejected. The test of various configurations by trial and error by taking advantage of the possibilities made available by such simulation programs does not solve the fundamental dilemma evoked above regarding the compatibility of both requirements.

16. The argument that a matching circuit is also inherently a resonating circuit is not convincing. It is certainly correct that matching networks well known to the skilled person, of the kind referred to by the appellant associating a capacitance and an inductance, will also resonate at a certain frequency. In general, however, said resonating frequency will be different from that for which the matching circuit has been conceived. The claimed subject-matter requires, however, that the matching functionality be achieved at its resonating frequency.

17. To avoid any misunderstanding, it should be stressed that the Board's objection does not rely on any inherent impossibility of realising a circuit that both resonates at a certain frequency and further includes the function of a matching circuit at said frequency, but on the fact that the appellant has not provided evidence that common general knowledge regarding the elaboration of matching circuits could compensate for the absence, in the patent application, of embodiments of the claimed invention. The absence of the required information amounts to undue burden on the shoulders of the skilled person attempting to carry out the claimed invention.

18. Consequently, the skilled person is not in a position to carry out the claimed invention on the basis of the application documents and common general knowledge. The application does thus not meet the requirements of Article 83 EPC.

Auxiliary request 9 - Admissibility

19. Auxiliary request 9 was filed during the oral proceedings before the Board, that is, at a particularly late stage of the appeal proceedings.

20. Article 13(1) RPBA relates to amendments filed by a party in the course of the appeal proceedings. It reads:

Any amendment to a party's case after it has filed its grounds of appeal or reply may be admitted and considered at the Board's discretion. The discretion shall be exercised in view of inter alia the complexity of the new subject matter submitted, the current state of the proceedings and the need for procedural economy.

21. The amendment made in claim 1 of auxiliary request 9 consists of deleting the feature regarding the ability of the resonating circuit to match the impedance of the wireless IC circuit with the impedance of the radiating plate. The amendment was intended to remedy to the objection regarding the insufficient disclosure of the invention under Article 83 EPC.

22. In support of the admissibility of the new request, the appellant emphasised that the objection raised under Article 83 EPC had been raised for the first time in the provisional opinion issued by the Board.

23. The appellant had, however, been informed of the misgivings of the Board with regard to the question of sufficiency of disclosure under Article 83 EPC before the oral proceedings. In its reply to the Board's communication, the appellant opted for defending the view that the invention had been disclosed in a manner sufficiently clear and complete to allow its reproduction.

24. The filing of auxiliary request 9 during the oral proceedings amounts to adopting a totally different strategy. It leads to the need to reconsider the relevance of the available prior art when deciding on the issues of novelty and inventive step, considering that the scope of claim 1 has become much broader as a result of the deleted features.

25. The need to address these issues at a particularly late stage of the proceedings, whether by the Board or by the examining Division, would directly conflict with the need for procedural economy referred to in Rule 13(1) RPBA. This appears all the more true considering that the claim of auxiliary request 9 reflects claim 1 of the original request which was withdrawn following the communication of the Extended European Search Report.

26. The Board, exercising its discretion under Rule 13(1) RPBA, therefore decides not to admit auxiliary request 9 into the proceedings.