T 2356/22 11-02-2025

Summary of Facts and Submissions

I. The patent proprietor and the opponent appealed against the Opposition Division's decision that, account being taken of the amendments made by the patent proprietor during the opposition proceedings in accordance with auxiliary request 3 then on file, the patent and the invention to which it related met the requirements of the EPC.

II. Oral proceedings took place on 11 February 2025.

The appellant/patent proprietor ("the proprietor") requested that the decision under appeal be set aside and that the patent be maintained on the basis of the main request, filed on 8 December 2021, or one of auxiliary requests 1 to 13, of which auxiliary requests 5, 8 and 11 were filed on 8 December 2021, auxiliary requests 1, 2 and 4 were filed on 8 February 2022 and auxiliary requests 3, 6, 7, 9, 10, 12 and 13 were filed on 24 February 2023.

III. The appellant/opponent ("the opponent") requested that the decision under appeal be set aside and the patent be revoked.

IV. The following documents are mentioned in this decision:

D1: WO 03/047468 A1

D2: WO 2007/103229 A2

D3: WO 2008/011261 A2

D4: WO 2008/070244 A2

D5: WO 2008/079962 A1

D6: WO 2008/106531 A1

D7: WO 2009/052188 A1

D9: US 2003/0167089 A1

D13: US 2006/0265056 A1

V. Independent claim 1 and dependent claims 2 to 8, 13 and 15 of the main request read as follows:

"1. An assembly for implanting a prosthetic aortic valve (10) in a native aortic valve of a patient's body, the assembly comprising:

a delivery catheter (100) comprising an inflatable balloon (110); and

a prosthetic aortic valve (10) configured to be radially collapsible to a collapsed state for introduction into the body on the delivery catheter (100) and radially expandable using the balloon (110) of the delivery catheter (100) to an expanded state for implanting the prosthetic aortic valve (10) at the native aortic valve in the body, the prosthetic aortic valve (10) comprising:

a radially collapsible and expandable annular frame (12), the frame having three angularly spaced commissure attachment posts and a plurality of angularly spaced, axial struts that are interconnected by at least three rows of circumferential struts including a first row of circumferential struts defining an inflow end of the frame (12), a second row of circumferential struts defining an outflow end of the frame (12), and a third row of circumferential struts positioned axially between the first and second rows of angled struts along the length of the frame (12) and adjacent the second row of circumferential struts, each row of circumferential struts including struts arranged in a zig-zag pattern extending around the circumference of the frame (12);

an annular skirt member (16) positioned inside of and secured to the frame (12); and

a leaflet structure comprising three leaflets, the leaflet structure having a scalloped lower edge portion secured to an inner surface of the skirt member (16) and three commissures formed at adjacent sides of the leaflets, each commissure being attached to one of the commissure attachment posts, the skirt member (16) disposed between the frame (12) and the leaflet structure (14),

characterized in that the the [sic] prosthetic aortic valve (10) further comprises a reinforcing strip (68), separate from the skirt member (16), secured to an inner surface of the scalloped lower edge portion of the leaflet structure (14),

wherein an upper edge of the skirt member (16) has a zig-zag shape that generally follows the zig-zag pattern of and is attached with sutures (56) to the third row of struts (22)."

"2. The assembly of claim 1, wherein the rows of circumferential struts include pairs of circumferential struts extending between two axial struts (30), the struts of each pair having adjacent ends interconnected by a generally U-shaped crown portion (26) defining a gap (28) between the adjacent ends."

"3. The assembly of claim 2, wherein the U-shaped crown portions (26) each include a horizontal portion extending between and connecting the adjacent ends of the pair of struts so as to define the gap (28) between the adjacent ends, the U-shaped crown portion (23) connecting the adjacent ends at a location offset from a natural point of intersection of the pair of adjacent struts."

"4. The assembly of claim 2, wherein each strut of a pair of struts connected at a common U-shaped crown portion (26) has one end connected to a respective axial strut (30) at a node (32) and another end interconnected to an adjacent end of the other strut of the same pair by the U-shaped crown portion (26)."

"5. The assembly of claim 2, wherein each pair of struts (22) of the third row that is connected at a common U-shaped crown portion (26) forms a cell with a pair of struts (24) in the second row that is connected at a common U-shaped crown portion (26)."

"6. The assembly of claim 5, wherein each cell is connected to an adjacent cell at a node (32), each node (32) interconnected with the third row of struts (22) by a respective axial strut (30) that is connected to and extends between the node (32) and a location on the third row of struts (20) where two struts are connected at their ends opposite U-shaped crown portions (26)."

"7. The assembly of claim 1, wherein the U-shaped crown portions (23) formed by the struts (46) of the third row are facing in an opposite direction of the U-shaped crown portions (23) formed by the struts (48) of the second row."

"8. The assembly of claim 1, wherein a lower edge of the skirt member (16) is attached with sutures to the first row of struts (20)."

"13. The assembly of claim 1, wherein the struts (20) of the first row are thicker than the struts (24) of the second row."

"15. The assembly of claim 1, wherein the frame (12) has exactly four rows of circumferential struts."

Claims 9 to 12, 14 and 16 are further dependent claims.

VI. The opponent's arguments, where relevant to this decision, can be summarised as follows.

Extension of subject-matter

Claim 1 of the main request required the rows of circumferential struts to include a third row of circumferential struts positioned axially between the first and second rows of angled struts. At no point did the original application mention any angled struts. The Opposition Division had taken the position that the expression "angled struts" was a linguistic error and that it was immediately apparent to a skilled reader that "circumferential struts" were meant. However, each of the features "angled struts" and "circumferential struts" had a clear, credible technical meaning. According to case law, the word "angled" had to be given its clear, credible technical meaning, and the description could not be used to give it a different one. Moreover, there was no indication in the patent that "angled" was intended to mean "circumferential". Figure 1 of the patent showed struts extending along a circumference of a prosthetic aortic valve at an angle with respect to the circumferential direction. The claim feature encompassed a configuration with angled struts extending radially outwards from the frame of the prosthetic aortic valve, in addition to struts extending in the circumferential direction. In conclusion, the technical meaning of the term "angled struts" could not simply be ignored. The proprietor's argument that the term "angled struts" further qualified the first and second rows of circumferential struts was a change of case and should not be admitted into the appeal proceedings. The Opposition Division had identified an error in that "the first and second rows of angled struts" lacked an antecedent basis in the claim. However, if there had indeed been an error, there would have been different possible ways of correcting it. One possibility other than interpreting the angled struts as the circumferential struts would have been to replace the definite article "the" with the indefinite "a". Claim 1 of the main request required the presence of a first, a second and a third row of circumferential struts together with first and second rows of angled struts. There was no disclosure in the original application of an embodiment with these rows of struts.

Moreover, claim 1 of the main request specified a frame having axial struts interconnected by at least three rows of circumferential struts. Claim 5 and paragraph [009] of the original application disclosed a plurality of rows of circumferential struts. Introducing the expression "at least three" into claim 1 constituted a selection that was not originally disclosed. Claim 1 excluded the possibility that the axial struts were interconnected by two rows of circumferential struts, but the original disclosure did not provide any basis for such an exclusion.

As correctly concluded by the Opposition Division, the original application did not at any point disclose that an upper edge of the skirt member was always attached to the penultimate row of struts. This was not necessarily the case with embodiments with four or more rows of struts, as encompassed by claim 1 of the main request.

The original application did not disclose an upper edge of the skirt member having a zig-zag shape as defined in claim 1 of the main request. Paragraph [062] of the application disclosed that "the upper edge of skirt 16 desirably has an undulated shape that generally follows the shape of the second row of struts 22 of the frame". Such an undulated shape was shown in Figures 16 and 17 of the original application and was not the same as a zig-zag shape. The original application itself distinguished between these shapes. The Opposition Division's statement, with which the proprietor agreed, that suturing the skirt to the frame would result in an edge having a zig-zag shape was not substantiated by any facts and was even contradicted by the disclosure. Such a zig-zag shape of the upper edge of the skirt member in an assembled state was not disclosed in the description or derivable from the figures of the original application. Figures 1 and 2 in particular could not provide a basis for the claimed feature as they were schematic and the edge of the skirt was not visible at all in these figures. What was visible was a suture line along the struts. The original application was also silent about an upper edge of the skirt member generally following the zig-zag pattern of the third row of struts. Paragraph [062] disclosed a skirt having an undulated shape that generally followed the shape of the second row of struts. An upper edge following a zig-zag pattern of a row of circumferential struts was not disclosed.

Claim 1 of the main request specified a first row of circumferential struts defining an inflow end of the frame and a second row of circumferential struts defining an outflow end of the frame. However, the original application did not disclose anywhere that a row of circumferential struts defined any end.

A number of features had been impermissibly omitted from claim 1 of the main request. One example was the annular skirt comprising slits intended to be aligned with crown structures at the circumferential struts of the frame. Moreover, claim 1 of the original application required a plurality of leaflets and two side flaps extending between respective ends of the upper edge and the lower edge. It also included the feature of a reinforcing bar being positioned against each side flap for reinforcing the attachments between the commissures and the commissure attachment posts. There was no indication in the original application that these features could be omitted, as had been done in claim 1 of the main request.

The first row of circumferential struts adjacent to the inflow end of the frame and the second row of struts adjacent to the outflow end of the frame as defined in claim 1 of the main request had been introduced on the basis of original claim 14. However, this claim comprised other features inextricably linked to those claimed, namely that the struts of the first row were thicker than the struts of the second row. Omitting the feature regarding the relative thickness of the first and second rows of struts from claim 1 and claiming this feature alone in claim 13 constituted inadmissible extensions of subject-matter. Moreover, the features of original claim 5, i.e. the circumferential struts extending between and not just interconnecting the axial struts, should have been introduced into claim 1 of the main request since claim 14 depended on claim 5, and claim 5 on claim 1, in the original application.

As the feature combination in claim 1 of the main request was not disclosed in the original application, the combination of the features of the dependent claims with the features of claim 1 was not disclosed in the original application either.

U-shaped crown portions having the features defined in dependent claims 2 to 7 of the main request were only disclosed in connection with embodiments having exactly three or four rows of circumferential struts. However, the claims were not restricted to such embodiments. Moreover, paragraph [049] disclosed the features of the crown structures in combination. Separating these features in dependent claims 2 to 7 constituted an extension of subject-matter. The original application did not disclose that the lower edge of the skirt member was attached with sutures to the first row of struts. The figures showed a lower edge of the skirt extending downwardly beyond the first row of struts. As a consequence, claim 8 of the main request contained added subject-matter. Claim 15 of the main request restricted the number of rows of circumferential struts to exactly four. However, in the original application, frames with four rows of circumferential struts were disclosed in combination with valves that were more than 29 mm in diameter and with four columns of struts for each 120° frame segment. Omitting these features in claim 15 constituted an extension of subject-matter.

Sufficiency of disclosure

According to claim 1 of the main request, a third row of circumferential struts was positioned between two rows of angled struts and, at the same time, was adjacent to a second row of circumferential struts.

The opposed patent did not disclose how a third row of struts might be arranged next to a second row at an end but also positioned between two other rows of struts.

The opposed patent did not provide sufficient information as to how a zig-zag-shaped upper edge of a skirt might be sutured to a row of circumferential struts having a zig-zag pattern. Top portions of the upper edge could not be wrapped around the circumferential struts due to the presence of axial struts extending from the zig-zag of the circumferential struts.

Novelty

The subject-matter of claim 1 of the main request was not novel in view of D7.

D7 disclosed an assembly for implanting a prosthetic aortic valve, including a balloon catheter and a collapsible and expandable prosthetic aortic valve. The prosthetic aortic valve (Figure 2) comprised an annular frame with three rows of circumferential struts arranged in a zig-zag pattern and a leaflet structure in the form of a three-leaflet membrane. According to paragraph [0044] of D7, a membrane support with a skirt could be affixed to the frame. Figure 2 showed lines of the leaflet structure covered by a skirt member in the area below a third row of circumferential struts. This meant that the skirt member terminated at the third row of circumferential struts, where it was attached to the frame with sutures (paragraph [0044]). The pattern on the circumferential struts was different from the pattern on the barbed axial struts in Figure 2 and indicated sutures. It followed that the upper edge of the skirt member had a zig-zag shape that followed the zig-zag pattern of the third row of struts. Moreover, the leaflet structure inherently had a scalloped lower edge portion, as aortic valves had this shape in nature. This was due to the presence of the leaflets and commissures and was supported by paragraph [0052], last sentence.

Inventive step

The subject-matter of claim 1 of the main request was not inventive when starting from D1.

This document disclosed an assembly for implanting a prosthetic aortic valve in a native aortic valve of a patient's body, comprising a delivery catheter, a prosthetic aortic valve (Figures 1, 23d and 23e) having a radially collapsible and expandable annular frame, an annular skirt member and a leaflet structure as defined in the preamble of claim 1 of the main request.

D1 did not disclose an upper edge of the skirt member having a zig-zag shape that generally followed the zig-zag pattern of and was attached with sutures to the third row of struts of the annular frame. According to Figure 23e of D2 the skirt member was punctually joined with sutures at different circumferential rows of struts, following the line at which the skirt member was joined to the leaflet structure.

The technical effect of the distinguishing feature of claim 1 of the main request was that the skirt member was more tightly secured to the annular frame. This solved the technical problem of providing more stable coupling. Alternatively, the technical effect could be considered to be that less material would be required for the skirt member. This solved the technical problem of reducing the amount of fabric required to provide the skirt member.

Since the leaflet structure and the skirt member were different elements, there was no need for the sutures for joining the skirt member to the annular frame to follow the contour of the leaflet structure. D1 provided a pointer towards the claimed solution in that it disclosed that the shape of the skirt member could be varied in some cases (page 33, third paragraph, tenth sentence) and that the skirt was joined along a zig-zag pattern to a first row of circumferential struts at the inflow end of the frame. The person skilled in the art would have provided a similar attachment to the third row of circumferential struts to obtain more stable coupling which more effectively avoided potential leakage and backflow between the annular frame and the leaflet structure (as taught in D1, page 33, third paragraph, sixth sentence). There was no technical difficulty in providing such an attachment following a zig-zag pattern, which would have to be spaced apart from the third row of circumferential struts only in the vicinity of the commissure attachment posts.

Moreover, D2 (Figure 5A), D3 (Figure 1B), D4 (Figure 6) and D5 (Figure 7) disclosed zig-zag shapes, which the person skilled in the art would have considered in order to reduce the amount of fabric required to provide the skirt member.

If the Board were to conclude that D7 is not novelty-destroying, the subject-matter of claim 1 of the main request would not involve an inventive step when starting from D7. D1 to D6 disclosed frames and skirt structures for supporting a tri-leaflet valve as defined in claim 1 of the main request.

The subject-matter of claim 1 of the main request was not inventive when starting from any of D3, D4 and D5.

D3 disclosed an assembly for implanting a prosthetic aortic valve in a native aortic valve of a patient's body, comprising a delivery catheter and a prosthetic aortic valve, the aortic valve having a leaflet structure having a scalloped lower edge portion secured to an inner surface of a skirt member (paragraph [0026] and Figures 1A and 1B). D3 also disclosed an upper suture line (Figure 1B) with a zig-zag shape connecting a skirt member to a third row of circumferential struts (paragraph [0025]).

Moreover, D4 disclosed an assembly for implanting a prosthetic aortic valve in a native aortic valve of a patient's body, comprising a delivery catheter and a prosthetic aortic valve (Figures 6 and 7), the aortic valve having a leaflet structure having a scalloped lower edge portion secured to an inner surface of a skirt member. Paragraph [0033] disclosed a bioprosthetic leaflet. Any bioprosthetic or biological leaflet had a shape matching the native leaflets, i.e. a scalloped lower edge portion. D4 also disclosed an upper suture line (Figure 6) with a zig-zag shape connecting a skirt member to a third row of circumferential struts.

In addition, D5 disclosed an assembly for implanting a prosthetic aortic valve in a native aortic valve of a patient's body, comprising a delivery catheter and a prosthetic aortic valve (Figures 1 and 2 and paragraphs [040] and [041]), the aortic valve having a leaflet structure having a scalloped lower edge portion secured to an inner surface of a skirt member (paragraph [041] disclosed a harvested natural valve as the leaflet structure, which inherently had a scalloped lower edge portion). D5 also disclosed an upper suture line (Figure 2) with a zig-zag shape connecting a skirt member to a row of circumferential struts.

If the Board were to conclude that any of D3 to D5 do not disclose leaflets having a scalloped lower edge portion, this feature would be disclosed in D9 (Figure 2) and D13 (Figure 1a). Under no circumstances could this feature provide an inventive step.

VII. The proprietor's arguments, where relevant to this decision, can be summarised as follows.

Extension of subject-matter

In claim 1 of the main request, the wording "a third row of circumferential struts positioned axially between the first and second rows of angled struts along the length of the frame (12) and adjacent the second row of circumferential struts" contained an obvious error. The word "the" showed that reference was being made to a feature that had already been introduced, but the claim had not previously made any mention of rows of angled struts. Instead, the claim had previously referred to "a first row of circumferential struts" and "a second row of circumferential struts". The person skilled in the art, reading the claim alone with a mind willing to understand, would interpret the wording "rows of angled struts" to mean "rows of circumferential struts". The correction had to be read into the claim, and for this reason a formal correction was not needed. If the wording "angled struts" was to be given a technical meaning, the circumferential struts as described and shown in the figures were in fact "angled struts". This wording explained that the circumferential struts were angled struts. A basis for the angle formed by the struts was provided in paragraph [048] and the figures of the original application. This argument had been made on page 9 of the reply to the opponent's statement of grounds. Consequently, it did not amount to a change of the proprietor's appeal case. The opponent's argument that there was no disclosure in the original application of three rows of circumferential struts in addition to two rows of angled struts failed to take into account that the first and second rows of angled struts were the first and second rows of circumferential struts.

Paragraph [009] and claim 5 of the original application provided a basis for frames with a plurality of rows of struts. Paragraph [048] and Figure 7 disclosed an embodiment with three rows of struts. This provided a basis for a frame having at least three rows of circumferential struts.

The original application disclosed specific embodiments of prosthetic valves with frames having three rows of circumferential struts (Figures 1-4, 7, 9, 19 and 23) and frames having four rows of circumferential struts (Figures 8, 10 and 24). Paragraph [053] stated that Figures 8 and 10 showed an alternative frame that was similar to the frame of Figures 7 and 9 except that it had four rows of struts. The person skilled in the art would understand that the features of the three-row frame were directly transferable to the four-row frame, unless explicitly stated otherwise. In the embodiment with three rows of circumferential struts, there were sutures on two of the rows, with the upper edge of the skirt being attached via sutures to the row adjacent to the uppermost row (Figures 1, 4, 19 and 23). In the embodiment with four rows of circumferential struts, there were sutures on three of the rows, with the upper edge of the skirt being attached via sutures to the row adjacent to the uppermost row (Figure 24). Moreover, Figures 3, 4, 7 and 9 showed vertically extending posts 18 having a group of upper holes in line with the upper two rows of circumferential struts, and a separate lower hole in line with the lower row of circumferential struts. Figures 8 and 10 showed vertically extending posts 18 each having a group of upper holes in line with the upper two rows of circumferential struts, and two additional separate holes, each in line with a respective one of the other rows of circumferential struts. Figure 13 showed a scalloped lower edge portion of a leaflet extending up to bars 62 having a group of holes that corresponded to the group of holes on the vertically extending posts. Paragraph [058] of the original application stated that "the point of attachment of the leaflets to the posts 18 can be reinforced with bars 62". As the scalloped lower edge portion of the leaflet structure was secured to an inner surface of the skirt member, the skirt member had to extend up to the region of the group of holes in the post 18, i.e. extend to and be attached to the row adjacent to the uppermost row. The original application therefore taught the person skilled in the art that the upper edge of the skirt was attached to the row of struts adjacent to the outflow row irrespective of whether the frame had three, four or more rows of circumferential struts.

Paragraph [062] of the original application disclosed that the upper edge of the skirt member had an undulated shape that generally followed the shape of the second row of struts of the frame depicted in Figures 1 and 2. It also disclosed that the upper edge was wrapped around the upper surfaces of the struts and secured in place with sutures. Paragraph [009] and Figures 1 and 2 of the original application disclosed that the struts were arranged in a zig-zag pattern. It followed that the upper edge of the skirt, when attached to the struts of the frame, had to have a zig-zag shape that generally followed the zig-zag pattern of the third row of struts within the meaning of claim 1 of the main request. The claim defined the shape of the upper edge of the skirt when assembled.

Paragraph [046] and claim 14 of the original application provided a basis for the first row of circumferential struts defining an inflow end of the frame and a second row of circumferential struts defining an outflow end of the frame.

The features recited in the summary section of the original application were listed as part of various representative embodiments. Independent claim 15 of the original application did not include many of these features. The features not present in claim 1 of the main request were merely optional features.

According to paragraph [050] of the original application, the feature that the struts of the first row were thicker than the struts of the second row was optional. Paragraphs [009] and [048] described axial struts interconnected by at least three rows of circumferential struts without stating that the circumferential struts extended between the axial struts.

Dependent claims 2 to 7 were based on paragraphs [010], [049] and [054] and claim 6 of the original application. Dependent claim 8 was based on paragraphs [056] and [062] and Figures 1, 2, 4, 5 and 29 of the original application. Claim 15 was based on paragraphs [052] and [053] and Figures 8, 10 and 25 to 29 of the original application.

Sufficiency of disclosure

In claim 1 of the main request, the wording "a third row of circumferential struts positioned axially between the first and second rows of angled struts along the length of the frame (12) and adjacent the second row of circumferential struts" contained an obvious error, and the person skilled in the art would interpret the rows of angled struts to mean the rows of circumferential struts. The person skilled in the art would have no difficulty providing a frame with a third row of circumferential struts positioned axially between first and second rows of circumferential struts. Such an arrangement was shown in Figures 1 to 4, 7 and 9 and described in paragraphs [019], [020] and [022] of the patent as granted.

A zig-zag-shaped upper edge of a skirt sutured to a row of circumferential struts having a zig-zag pattern was shown in Figures 1, 2 and 4 and described in paragraphs [027], [033], [010] and [019] of the patent as granted. The person skilled in the art would have no difficulty implementing this teaching.

Novelty

D7 did not disclose an upper edge of a skirt member having a zig-zag shape that generally followed the zig-zag pattern of and was attached with sutures to a third row of struts of an annular frame of a prosthetic aortic valve. Figure 2, which was schematic, showed some lines of a leaflet structure which did not extend below a third row of circumferential struts and other lines which did. It could not be inferred from this figure that the skirt member terminated at the third row of circumferential struts. The pattern on the circumferential struts was not described in D7, and it could not be inferred what the pattern indicated. Moreover, D7 did not disclose a leaflet structure having a scalloped lower edge portion secured to an inner surface of a skirt member. Rather, a circumferential line in Figure 2 of D7 pointed to the fact that the lower edge of the skirt member in that figure was flat. The opponent's statement that the leaflet structure had to have a scalloped lower edge portion, as aortic valves had this shape in nature, was not supported by any evidence.

Inventive step

D1 did not disclose an upper edge of a skirt member with a zig-zag shape that generally followed the zig-zag pattern of and was attached with sutures to a third row of struts of an annular frame of a prosthetic aortic valve.

This distinguishing feature created a more durable prosthetic aortic valve because the zig-zag shape of the upper edge of the skirt attached with sutures to the struts allowed for tight attachment. Hence, the distinguishing feature solved the problem of how to increase the reliability of the prosthetic heart valve of D1.

The person skilled in the art would not have modified the attachment of the skirt member of D1 in the claimed way. The skirt member in Figures 23d and 23e of D1 extended to and was attached to posts which ended at an uppermost row of circumferential struts. This attachment had to be kept in order to ensure that the valve according to D1 worked correctly. Moreover, D1 would not have prompted the person skilled in the art to apply a zig-zag cut, as D1 taught attaching the skirt member to three upper rows of struts of the annular frame, which provided a working device.

None of D2, D3, D4 and D5 disclosed the distinguishing feature. They disclosed sutures arranged along a row of struts that did not correspond to the third row of struts according to claim 1 of the main request.

The distinguishing features of claim 1 of the main request over each of D3, D4, D5 and D7 were the leaflet structure having a scalloped lower edge portion secured to an inner surface of the skirt member and an upper edge of the skirt member having a zig-zag shape that generally followed the zig-zag pattern of and was attached with sutures to the third row of struts. Figures 1A and 1B and paragraph [0026] of D3 disclosed an arcuate line of a leaflet structure at the outflow end but did not teach any scalloped lower edge portion of the skirt member as defined in claim 1 of the main request. With respect to D4 and D5, the opponent had not provided any evidence that a bioprosthetic leaflet or a harvested natural valve necessarily had a scalloped lower edge portion.

The distinguishing features solved the problem of how to increase the reliability of the prosthetic heart valve of each of D3, D4, D5 and D7.

None of these documents or the common general knowledge suggested the distinguishing features for solving this problem. D1, D2 and D6, mentioned by the opponent, did not provide any such suggestion either. It followed that the subject-matter of claim 1 of the main request was inventive when starting from any of D3, D4, D5 and D7.