T 0847/04 13-07-2006

Reasons for the Decision

1. The appeal is admissible.

2. Amendments

After due consideration of the amendments made to the application documents, the Board is satisfied that the amendments to the application documents according to the appellant's request comply with the formal requirements of the EPC, and in particular with those set forth in Article 123(2) EPC. In particular, claim 1 is based on claim 1 as published together with the embodiments disclosed in the description as published with reference to Figures 1 and 3; independent claim 7 is based on claim 7 as published together with the passages on page 5, line 28 et seq. and page 6, lines 9 to 12 of the description as published and the disclosure of the embodiments of Figures 5 to 7; and dependent claims 2 to 6 and 8 to 20 are based on the features and the alternatives defined in claims 2 to 16 as published.

Furthermore, the description has been appropriately amended and brought into conformity with the invention as defined in the claims (Article 84 EPC, second sentence and Rule 27(1)(c) EPC).

3. Independent claim 7 - Rule 86(4) EPC

Independent claim 7 upon which the decision under appeal was based specified that the "glass-ceramic material [...] fully or partly surrounds the [...] sensor electrode". This feature has been amended in present claim 7 so as to specify that the "glass-ceramic material [...] fully surrounds the [...] sensor electrode or at least a face thereof". In the decision under appeal the examining division held that the claims as published did not mention a sensor electrode that is not completely surrounded by the glass-ceramic material and concluded that claim 7 then on file related to unsearched subject-matter within the meaning of Rule 86(4) EPC.

However, the corresponding independent claim 7 of the application as published and on which the search was based specified that "the glass-ceramic material which [...] surrounds the sensor electrode(s) [...] is homogeneous" without however excluding that the sensor electrode is only partly surrounded by the glass-ceramic material. In addition, the possibility that the sensor electrode is not completely surrounded by the glass-ceramic material was not only not excluded by the formulation of the published version of the claim, but also implicitly implied by claim 12 as published and dependent on claim 7 and according to which a side of the electrode sensor was "coated with a layer of glass-ceramic material which covers the entire cross-section of the hole or slot, the material being preferably [...] uniform with the rest of the homogeneous, glass-ceramic material" [emphasis added by the Board], thus clearly pointing at alternative embodiments encompassed by the subject-matter of claim 7 and in which the sensor electrode is only partly surrounded by the homogeneous glass-ceramic material. In addition, these alternative embodiments of the published claim 7 were explicitly disclosed in - and therefore supported by - the description as published (see Figures 5 to 7 and the corresponding description).

Having regard to the above, the formulation of claim 7 as published implicitly encompassed that the sensor electrode was only partly surrounded by the glass-ceramic material and consequently it has to be assumed that the search also covered a pressure housing with a sensor electrode only partly surrounded by the glass-ceramic material.

The Board concludes that the feature of independent claim 7 referred to by the examining division is deemed to have been covered by the search and that the corresponding amendment does not render the claimed subject-matter "unsearched" within the meaning of Rule 86(4) EPC (see in this respect decisions T 915/03, points 3 and 4 of the reasons, T 377/01, point 3.1, and T 613/99, point 2). Consequently, the Board cannot follow the examining division's view that the amended claim is inadmissible under Rule 86(4) EPC by virtue of the amendments mentioned above.

4. Independent claims 1 and 7 - Inventive step

4.1 During the first-instance proceedings the examining division did not object to the patentability of the subject-matter of claim 1 and dependent claims 2 to 6, and the Board is satisfied that these claims define novel and inventive subject-matter over the available prior art (Articles 52(1), 54 and 56 EPC). In particular, none of the documents on file discloses or suggests a capacitive sensor electrode anchored within the wall of a pressure housing or flow guide by means of a glass-ceramic material encapsulating the electrode and the corresponding electrical connection as claimed.

4.2 In the decision under appeal the examining division held that the subject-matter of independent claim 7 was rendered obvious by the disclosure of document D1 and the teaching of document D2. The Board, however, cannot follow the examining division´s finding in this respect for the following reasons.

4.2.1 Document D1 discloses a capacitive pressure transducer comprising a capacitive electrode bonded to a nonconductive substrate and a diaphragm capacitive electrode disposed on the substrate, the diaphragm electrode having a recess portion such that the two electrodes are electrically isolated from each other (Figure 1 together with column 4, lines 4 to 33 and column 6, lines 21 to 30).

Document D2 is directed to a pressure chamber such as a hydraulic pressure line, a vessel, a pipeline, etc., comprising a pressure sensor for measuring the pressure of a fluid medium within the chamber (abstract, column 1, lines 8 to 16 and lines 58 to 64, and column 3, lines 2 to 4). The pressure sensor is of the resistive type (column 2, line 57 to column 3, line 6) and comprises a resistance element and two connecting electrical conductors positioned in a transverse passage of a wall of the chamber and anchored to the wall by means of a sealing insulating homogeneous material extending from the pressure sensor through the passage towards the side of the wall opposite the medium (abstract and Figures 1, 3, 5, 7 and 8 together with the corresponding description).

4.2.2 The subject-matter of claim 1 differs from the disclosure of document D1 in essence in

- the provision of the capacitive transducer in a passage of the wall of a pressure housing or pressure-resistant flow guide as claimed,

- the galvanic contact arrangement between the diaphragm electrode and the material of the wall, and

- the use of a glass-ceramic material as substrate material.

The subject-matter of claim 7 differs from the disclosure of document D2 in that

- the pressure sensor is of the capacitive type instead of the resistive type and requires a reference electrode in addition to the sensor electrode,

- in all the features relating to the reference electrode, and

- in the use of a glass-ceramic material as sealing insulating homogeneous material.

The capacitive and resistive electrode sensors respectively disclosed in documents D1 and D2 require by their nature different arrangements and in this respect the Board concurs with the appellant´s contention that the skilled person would not have considered combining isolated features of the electrode arrangements disclosed in documents D1 and D2. In addition, even if the skilled person would have considered incorporating features of the teaching of document D2 into the arrangement disclosed in document D1 as held by the examining division, he would not have arrived at the claimed capacitive electrode arrangement. In particular, document D1 specifies glass (column 4, lines 5 to 8) and document D2 specifies glass, ceramic and plastics (column 5, lines 61 to 63) as alternative anchoring insulating materials for the sensor electrode; thus, none of the documents discloses specifically the use of a material of the glass-ceramic type as required by the claimed subject-matter and the sealing and electrical effects achieved by the use of this material (page 1, lines 17 to 37 and page 5, lines 6 to 11 of the application as published). In addition, the use of the sensor of document D1 in a passage of a pressure wall as disclosed in document D2 would lead to the diaphragm reference electrode of document D1 being arranged in contact with the non-conductive substrate in which the capacitive electrode is inserted (figures of document D1 and the corresponding description), and not arranged in galvanic contact with the material of the wall of the pressure chamber in which the encapsulating material of the capacitive electrode is inserted as required by the claimed subject-matter; thus, the combination of documents D1 and D2 would result in an arrangement having capacitive characteristics different from those of the claimed arrangement.

Accordingly, neither the structural nor the functional features of the sensor arrangement defined in claim 7 are rendered obvious by the disclosure of documents D1 and D2 within the meaning of Article 56 EPC.

The Board is also satisfied that none of the remaining documents on file suggests the claimed subject-matter.

4.2.3 Having regard to the above, claim 7 and dependent claims 8 to 20 define patentable subject-matter within the meaning of Articles 52(1), 54 and 56 EPC over the available prior art.

5. Claims 1 and 7 - Unity of invention (Article 82 EPC)

The objection of lack of unity raised under Article 82 EPC by the examining division in the decision under appeal was based in essence in the examining division's finding that the subject-matter of claim 7 did not involve an inventive step and that consequently no common inventive concept linking the subject-matter of claims 1 and 7 could be identified.

However, as set out in point 4.2.2 above, the subject-matter of claim 7 involves an inventive step over the available prior art by virtue of the capacitive arrangement including a capacitive sensor electrode anchored within the wall of a pressure housing or flow guide by means of a glass-ceramic material encapsulating the electrode and the corresponding electrical connection as claimed. In addition, although claim 1 does not specify a reference electrode, claim 1 also includes the aforementioned capacitive sensor electrode arrangement (see point 4.1 above). Thus, claims 1 and 7 have in common technical features which define a contribution over the prior art within the meaning of Rule 30(1) EPC. In these circumstances, the Board cannot follow the examining division's finding that there is no common inventive concept linking the subject-matter of claims 1 and 7 (Article 82 EPC).

6. In view of the above, the decision under appeal is to be set aside. In addition, being satisfied that the patent application as amended according to the present request of the appellant and the invention to which it relates meet the requirements of the EPC (Article 97(2) EPC), the Board, in accordance with Article 111(1) EPC, considers it appropriate to exercise favourably the power within the competence of the examining division to order grant of a patent.