EP 3 639 792 B1 relates to a sealing member for prosthetic heart valve comprising a plush fabric having a variable thickness. Such valves include an improved outer skirt of plush fabric for reducing perivalvular leakage.
Brief outline of the case
Claim 1 as granted lacked N over a document not mentioned in the ESR of a divisional application. The patent was maintained according to AR1.
The proprietor appealed. The board confirmed the maintenance according to AR1.
The whole discussion was about the meaning of a “variable thickness“.
Two variants are possible:
- Variant 1: the plush fabric has different thickness values at different positions
- Variant 2: the thickness of the plush fabric at a given position is variable as it can be compressed
The proprietor’s point of view
For the proprietor, the skilled person would only consider Variant 1.
The proprietor argued that from paragraph [0076] of the patent the skilled person would understand that the term “variable” in relation to the thickness of the plush fabric was to be understood as the opposite of “constant“.
Paragraph [0078] did not allow the conclusion that a plush fabric that “compresses under load … and returns to its original size and shape when the load is relieved” would be considered a plush fabric “having a variable thickness” within the meaning the patent in suit.
Variant 2 was unduly broad and did not find support in the patent in suit.
Furthermore, paragraph [0057] contained an explicit definition of the term “variable thickness”, according to which the plush fabric had different thickness values at different positions. In contrast to paragraph [0078], paragraphs [0043] and [0125] did not relate to the compressibility of the plush material but to the sealing member’s behaviour when stretched along its length.
This distinction had to be taken into account when interpreting the term “variable thickness“. It would be clear to the skilled person that variations in thickness due to stretching, Variant 2b, were potentially included, while variations in thickness due to compression of the compliant material, Variant 2a, had to be ruled out.
With regard to the interpretation according to Variant 2, the term “variable” would not limit the scope of the claim in any way since all plush fabrics will change thickness when compressed. The skilled person would therefore interpret the patent claim as clearly meaning that the plush fabric had “different thicknesses in different locations when in the free, undeformed state“.
The board’s decision
For the board, the meaning of the language of the claims is to be derived by the technical context provided by the description and the drawings, due account being taken of the claims themselves being the starting point and the basis of the assessment, cf. T 0847/24, Reasons 3.1 and 3.2.
Interpreting the claim’s features must, however, be distinguished from reading into the claim a feature which is only disclosed in the description, since this would be at odds with the first principle listed in G 1/24, see also T 0981/23, Reasons 2.2.3 (ambiguous feature), and T 1473/19, Reasons 3.16.1 (decision on interpretation by the deciding body, pre G 1/24).
Contrary to the proprietor’s view, on the basis of the disclosure in the description, in particular paragraphs [0043], [0078] and [0125]) the board was of the opinion that an interpretation pursuant to Variant 2 cannot be ruled out.
Paragraph [0078] discloses that the pile layer forming the plush fabric can be compliant such that it compresses under a load. Paragraph [0043] mentions a decrease in the thickness of the sealing member when the axially extending filaments move from the deformed or twisted state to the less deformed or twisted state. Paragraph [0125] discloses that the thickness of the sealing member can vary as the fabric stretches and relaxes.
The skilled person would understand from all these paragraphs that the thickness of the plush material is dynamically variable due to compression or stretching.
The fact that in some other embodiments the thickness may be different in different locations of the fabric, as described in paragraph [0057] of the patent, does not exclude an interpretation according to or encompassing Variant 2 since it is possible to have a thickness that varies both spatially and as a result of change of state of the fabric.
The board noted that it is not required that claim language be interpreted such that the claimed subject-matter is limited over the prior art. Moreover, the fact that the fabric is a plush fabric defines additional properties of a fabric having a thickness that is variable by means of compression or stretching.
As for paragraph [0057] of the patent, this passage relates to an exemplary embodiment illustrating what could be meant by the term “variable thickness” in relation to the skirt. The same is true of the term “constant thickness” in paragraph [0076].
By contrast, the wording of claim 1 refers to the “variable thickness” of the fabric, thus indicating that this is a property of the material, linked to a change of state.
The board took the view that making a distinction between Variants 2a or 2b would go beyond claim interpretation. The claim is completely silent as to what might cause the variability of the thickness. Hence, including the limitation of Variant 2a or 2b would amount to reading into the claim a feature only disclosed in the description, which would be impermissible.
For the board, “a plush fabric having a variable thickness“, meaning that the thickness of the plush fabric at any given position is variable, for instance under a load due to compression or as the fabric stretches, is encompassed by claim 1.
On this basis, the board confirmed the lack of N of claim 1 as granted.
Comments
G 1/24 does not allow a selective “consultation” of the description
It can be agreed with the board that G 1/24 does not allow to read in a claim a limiting feature found in one place of the description and disregard another place in the description which gives a different interpretation of the same feature.
For the skilled person, all possible technically reasonable interpretations of a claimed feature have to be taken into account. This is even more the case when two possible interpretations are contained in one and the same description.
If only one of the limitations would have been originally disclosed, then the broader claim would not be compliant with Art 123(2).
It does however not mean that, according to G 1/24, a limiting feature within the description is always read into the claim. This is only possible if the limiting feature is applicable to all disclosed embodiments. A broadening feature, even limited to one embodiment, will not be read into the claim, but will allow the limited claim to be confronted with a broader piece of prior art.
Effect of G 1/25
G 1/25, Reasons 10, when applying T 439/22-2, would actually lead to both interpretations being “read” into the claim, paragraph [0057] for Variant 1 and paragraph [0078] for Variant 2. One of those variants lacking N, the whole claim lacks N.
With G 1/25 and the interpretation of T 439/22-2 given therein, cf. Reasons 10, the board’s position in Reasons 2.3 of the present decision, according to which interpreting the claim’s features must be distinguished from reading into the claim a feature which is only disclosed in the description, is not any longer tenable.
T 0847/24 has been commented in the present blog.
T 0981/23 has also been commented in the present blog.
T 1473/19 has as well been commented in the present blog.
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