T 0846/16 16-10-2017

1. Admissibility of the appeal (Rule 101(1) EPC)

1.1 The appeal is admissible under Rule 101(1) EPC and complies with Article 12(2) RPBA.

Rule 101(1) EPC refers to Rule 99(2) EPC which requires that the statement setting out the grounds of appeal shall indicate the reasons for setting aside the impugned decision. Similar requirements can be found in Article 12(2) RPBA according to which the statement setting out the grounds of appeal shall set out clearly and concisely the reasons why it is requested that the decision under appeal be reversed.

1.2 The respondent argued that these requirements are not complied with since there were allegedly no reasons for setting aside the decision and further the statement setting out the grounds of appeal concerned a new case.

The board does not share this view. Indeed, the statement setting out the grounds of appeal comprises a new line of argumentation of the opponent. However, this new line of argumentation is the reaction of the opponent to the changes in argumentation of the patent proprietor and a corresponding change in opinion of the opposition division which occurred only very late in the proceedings, i.e. during the oral proceedings before the opposition division.

Further, the statement setting out the grounds of appeal clearly states that the claims underlying the decision of the opposition division go beyond the application as filed, see for example page 3, second paragraph of the statement. From this content it can be deduced that the opponent wished the impugned decision to be set aside based on his new argumentation.

1.3 According to the impugned decision, the amended feature H) reading "the communication interface (27) is isolated from the first power source (40)", which formed part of the independent claims as granted, does not contravene Article 123(2) EPC. However, the opposition division had in the annex to the summons to oral proceedings indicated that the subject-matter of claim 1 of the patent, that already contained the disputed feature H), contravened Article 123(2) EPC. Thus, there was an unexpected change in the opinion of the opposition division during the oral proceedings.

1.4 The patent proprietor had also changed their argumentation only during the oral proceedings before the opposition division.

In their reply to the opposition dated 12 August 2014, the patent proprietor argued that the amended feature H) was allowable since the description of the A1 publication stated in paragraph [0008], that the isolation of the inverter system from the first power source is optional. Further, the text of the patent had, before grant, been corrected under Rule 139 EPC to state in paragraph [0031] that "the GND of the motor control circuit Ca has the same electrical potential (high voltage system GND) as the GND of a high voltage circuit Cb to which a high voltage is supplied from the high voltage power source". On the basis of this correction under Rule 139 EPC the patent proprietor argued that the motor control Ca was not isolated from the first power source since both shared the same ground (GND).

In response to the summons to oral proceedings dated 18 September 2015 the patent proprietor had argued that the amendments underlying the objection of the opponent under Article 123(2) EPC were the consequence of an error in the translation and that the opponent's arguments were therefore not relevant.

Thus, up until the oral proceedings before the opposition division, the patent proprietor had consistently stated that the amendment of both the description and claims of the patent as granted was the consequence of a translation error.

During the oral proceedings before the opposition division, however, the patent proprietor argued that there had been a mistake in originally filed claim 1 by claiming that the inverter system is isolated. The correct statement was "that the inverter uses an isolated inverter", which was evident from the description. The amendment was "thus not due to an error of translation". The fact that this statement was made with respect to an objection under Article 83 EPC has no bearing on its content, which is that during the oral proceedings before the opposition division the patent proprietor no longer stated that the amendments to the claimed subject-matter served to correct a translation error.

The patent proprietor's new arguments obviously caused the opposition division to reverse its opinion on this objection.

1.5 The board thus concludes that the opponent was confronted with a new situation regarding the opposition ground under Article 100(c) EPC during the oral proceedings before the opposition division.

Under such circumstances, the board considers it as an appropriate procedural reaction of the opponent to change their corresponding argumentation under Article 123(2) EPC during the appeal proceedings.

Consequently, the board concludes that the appeal complies with Rule 99(2) EPC and Rule 101(1) EPC.

The appeal is therefore admissible.

2. Admissibility of the appellant's new arguments (Article 12(4) RPBA)

Regarding the admissibility of the appellant's arguments under Article 123(2) EPC as such, the same reasoning as with respect to the admissibility of the appeal applies.

As discussed above, the argumentation of the patent proprietor regarding Article 100(c) EPC had changed only during the oral proceedings before the opposition division. Therefore, the board considers it as appropriate that the opponent brought forward new arguments in reaction to the change in argumentation of the patent proprietor and the change in the opinion of the opposition division in the opponent's statement of grounds of appeal.

The appellant's arguments regarding Article 123(2) EPC are therefore also admissible.

3. Substance of the amendment (Article 123(2) EPC and Rule 139 EPC)

Main request

3.1 The respondent argued that Rule 139 EPC was not pertinent for the determination of the allowability of amendments.

The board does not share this view. Rule 139 EPC constitutes lex specialis to Article 123(2) EPC. Thus, the requirements of Rule 139 EPC are to be taken into account in the assessment of an amendment under Article 123(2) EPC if the amendment involves the correction of an obvious mistake according to Rule 139 EPC.

Since the feature which had been objected to stems from the correction of an alleged obvious mistake under Rule 139 EPC, i.e. from the amendment of "the inverter system (20) is isolated from the first power source (40)" to "the communication interface (27) is isolated from the first power source (40)" in the independent claims 1, 3 and 4 of the main request, it has to be established, whether the correction fulfils the requirements of Rule 139 EPC.

The requirements of Rule 139 EPC for an amendment that concerns the description, claims or drawings, are that the mistake must be obvious in the sense that it is immediately evident that nothing else would have been intended than what is offered as the correction.

3.2 No mistake is obvious with respect to the unamended feature H) "the inverter system (20) is isolated from the first power source (40)".

The English translation of the originally filed PCT application PCT/JP2007/069096 corresponds to the published European patent application EP 2 120 331 A1.

The description of the A1 publication indicated consistently that the inverter system is isolated from the first power source, see e.g. paragraphs [0007], [0008] and [0009]. The corrected pages of the English translation which were filed on 16 March 2012 and on 14 September 2012 did not amend this disclosure.

This is also consistent with the claims of the A1 publication, in particular independent claim 1. Only with the communication of intention to grant according to Rule 71(3) EPC did the examining division amend paragraph [0007] of the description, but left paragraphs [0008] and [0009] unamended. The patent proprietor consented to this amendment. Thus, even the patent as granted still contains the alleged mistake in paragraphs [0008] and [0009].

Figure 1 showing the embodiment of the claimed inverter system depicts three boxes indicated by dashed lines labelled Ca, Cb and Cc. It is evident from this figure that the switching element 21 is arranged between box Cb, relating to the first (high voltage) power source, and box Ca, relating to the third (low voltage) power source. Typically, semiconductor switching elements of the type used in such systems are capable of carrying very high voltages and currents on their power path, i.e. on the side belonging to box Cb, while requiring only very small control voltages for their gate control, i.e. on the side belonging to box Ca. This is further consistent with paragraph [0031] of the A1 publication according to which "A motor control circuit Ca ... is isolated by switching element 21 from a high voltage circuit Cb to which a high voltage is supplied from the high voltage power source 40". The board can thus not identify any contradiction regarding the unamended feature H) "the inverter system (20) is isolated" from the first (high voltage) power source.

There is further no reason why different potentials could not share the same ground connection. In the majority of electrical supply systems the potential of the ground connection is anyway zero volts (i.e. "earth").

Consequently, the board concludes that there is no obvious mistake in the originally filed claims that could justify a correction under Rule 139 EPC.

3.3 Furthermore, even if it were assumed that the alleged mistake was obvious, it is not immediately evident what the correction should be.

If the expression that "the inverter system (20) is isolated from the first power source (40)" is to be replaced by a correction under Rule 139 EPC, it must be immediately evident what that correction should be.

Figure 1 in combination with the description according to the A1 publication indicates three voltage levels, first (high) voltage, second (low) voltage and third (lowest) voltage as well as many functional units which might be isolated from the first voltage level.

The respondent argued that the communication interface 27 was isolated from the first power source. They further argued that because the photocoupler 27b isolated the communication interface 27 from the motor controller Ca, it was evident that the replacement of "inverter system" by "communication interface" was the appropriate correction under Rule 139 EPC.

However, figure 1 as well as the description paragraph [0008] of the A1 publication define that the isolation of the inverter system from the first power source uses an isolated DC-DC converter. The isolated DC-DC converter might therefore also be interpreted as being the immediately evident correction. This applies even more so since the description explicitly defines it as the means for isolating the inverter system, as described in paragraphs [0007] and [0008] of the published European patent application.

Since there are at least two plausible corrections for the alleged mistake, however with different technical consequences, it follows that neither of these two possible corrections can constitute the immediately evident correction in the sense of Rule 139 EPC.

3.4 Consequently, with respect to amended feature H), there is neither an obvious mistake nor is it immediately evident what its correction should be. Therefore, the amendment does not comply with Rule 139 EPC.

3.5 Moreover, the A1 publication does not disclose the disputed amended feature H) in the same context as the unamended feature H) it replaced. To the contrary, the unamended feature H) "the inverter system (20) is isolated from the first power source (40)" is described as the difference over the prior art in the A1 publication. This is also evident from a comparison of figures 1 and 2 of the A1 publication. Both figures show a communication interface that is isolated from the motor control via a photocoupler. However, only figure 1, which illustrates the claimed invention, shows an "isolated DC-DC converter" for isolating the inverter system from the first power source, while in figure 2, illustrating the prior art, the DC-DC converter is depicted as "non-isolated".

Thus, there is no basis for amended feature H) in the A1 publication.

3.6 Since the amendment of feature H) is neither a correction of an obvious mistake under Rule 139 EPC nor has a basis in the A1 publication, the amendment contravenes Article 123(2) EPC.

Consequently, the main request is not allowable.

3.7 First auxiliary request

Independent claim 1 of the first auxiliary request differs from claim 1 of the main request only in that amended feature H) reads "the communication driver (27a) is isolated...".

As discussed above with respect to the main request, there is no obvious mistake under Rule 139 EPC in unamended feature H). There is further no basis in the specification justifying the amendment of feature H) under Article 123(2) EPC. Thus, since the amendment in the main request replacing "inverter system (20)" by "communication interface (27)" is not allowable, a replacement of the former by only a sub-feature of the communication interface 27 is also not allowable.

Therefore, the board concludes that the amendment in the first auxiliary request contravenes Article 123(2) EPC.

Even if it were assumed that the first auxiliary request did not contravene Article 123(2) EPC, it in any case contravenes Article 123(3) EPC because instead of the whole communication interface being defined as isolated from the first power source, in claim 1 of the first auxiliary request only a part of the communication interface, i.e. the communication driver, is defined as isolated from the first power source, thus the protection conferred is extended, because it covers embodiments in which other parts of the communication interface are not isolated from the first power source.

3.8 Second to fourth auxiliary requests

Independent claims 1, 3 and 4 of the second to fourth auxiliary requests comprise a similar replacement for the feature "the inverter system is isolated from the first power source", and the further amendments in these claims have no bearing on this feature. Thus the arguments concerning the amendment in the main request apply mutatis mutandis to the second to fourth auxiliary requests.

Consequently, independent claims 1, 3 and 4 of the second to fourth auxiliary requests also contravene Article 123(2) EPC.

4. Conclusion

Since there is no allowable request on file, the patent has to be revoked.