T 971/10 – Substantially Circular

This appeal deals with the refusal of the application under consideration by the Examining Division (ED).

Claim 1 of the application as filed (which was also claim 1 of the main request before the Board) read:

1. A gas-liquid contacting tray suitable for horizontal mounting in a normally vertical column, which tray comprises

• a tray plate with substantially circular circumference and having top and bottom surfaces, which tray plate is provided with passages for gas between the bottom and the top surface, and on which tray plate two semi-circular tray sections are defined by a virtual diametrical line of the tray plate; and
• a total of three downcomers for guiding liquid from the top surface of the tray plate to below the tray, each downcomer extending from an inlet opening arranged in the tray plate to a downcomer outlet opening below the tray,

wherein two of the downcomers are arranged in the corners of one of the semi-circular tray sections, and wherein the third downcomer is arranged on the other tray section substantially along a radius of the tray that is perpendicular to the diametrical line.

The ED held that the claim features “substantially circular” and “substantially along a radius” did not fulfil the requirement of clarity of A 84.

The applicant also filed an auxiliary request wherein these features were deleted.

Main request

[1.1] According to A 84 the patent claims must define the subject-matter for which protection is sought and be clear. The importance of the clarity requirement is due to the necessity of legal certainty, as the purpose of the claims is to enable the protection conferred by a patent to be determined (see Case Law of the Boards of Appeal of the EPO, 6th edition, 2010, chapter II.B). Insofar, the Board agrees with the appellant.

In the present case, the question at issue is whether the expressions “substantially circular circumference”, “substantially along a radius of the tray”, “normally vertical column” and “substantially conforming to the circumference of the tray” mentioned in the claims to define a gas liquid contacting tray fulfil the above requirements.

[1.2] The appellant admitted that the terms in question introduce a certain level of unclarity but was of the opinion that this level did not exceed the one generally inherent in patent claims. Their deletion would unjustly limit the patent protection since it was clear from the description of the application that the trays need not be exactly circular.

By referring to decisions T 198/01 and T 386/07, the appellant argued that the term “substantially” was found clear in decisions of the Board of Appeal. There was no reason to apply to the present claims the requirement of clarity more strictly than usual. Decision T 728/98 cited by the ED did not apply in the present case since the feature “circular” was not essential for delimiting the present invention from the prior art.

[1.3] The Board agrees with the appellant insofar as decision T 728/98 does not seem to be relevant for the present case. In this decision, it was found that the term “substantially pure” used to define a chemical compound was unclear. On a first sight, it might appear that the term “substantially pure” would display the same “level of clarity” as the terms “substantially circular” and “substantially along a radius”. However, upon deleting the expression “substantially” it is apparent that the term “pure” in relation with a chemical compound is still vague as it does not define any particular level of purity. In contrast, the terms “circular” and “along a radius of the tray” define a particular geometry of a physical device.

The Board further agrees that it would be unfair to restrict the claimed subject-matter to “perfectly” circular trays.

However, as is established in R 35(12) EPC (1973), last sentence, patent applications should contain only technical terms which are generally accepted in the field in question. Accordingly, for the purpose of A 84, a particular technical term has to be given the meaning it usually has in the particular technical field concerned.

This means that in the field of gas-liquid contacting apparatuses the term “circular” used for defining the shape of a tray never means ‘exactly’ or ‘perfectly’ circular but only circular within those tolerances which are usual in the manufacture of such apparatuses. The same applies to the term “along a radius of the tray” used to define the location of the third downcomer.

As a consequence, the use of the term “substantially” in combination with “circular” and “along a radius” suggests that deviations are included which are larger than those accepted tolerances. Since there is no explanation of what the deviations might be, the terms become vague and undefined with the result that it is no longer possible to determine the extend (sic) of protection conferred by the application (see also decision of the Enlarged Board of Appeal G 2/88 [2.5]).

On the contrary it might appear to be intended that the application shall include future embodiments, not thought about at the application date, since the application in suit does not disclose any other than a circular shape of the trays or any other arrangement of the third downcomer than along a radius of the tray.

The same arguments apply to the term “normally vertical column” when compared with the definition given on page 84 of “The Petroleum Handbook” filed by the appellant during the examining proceedings and to the term “substantially conforming to the circumference of the tray” used in dependent Claims 5 to 7 of the main request.

Concerning decisions T 198/01 and T 386/07, the Board observes that the assessment of clarity is dealt with in a different manner. In particular, those decisions do not consider the fact that the meaning of technical terms in claims is neither absolute nor theoretical but governed by what is generally accepted in the technical field in question.

Further, the compositions of the Boards of Appeal vary from case to case, depending on the specific technical field. Hence, the assessment of the merits of a case may also vary to a certain degree due to different approaches with respect to the assessment of technical features. There cannot be an ultimate right for an equal assessment in all cases since such assessments are generally subject to mental development.

[1.4] Having regard to the above, the Board concludes that the claims of the main request do not comply with the requirements of A 84 since the terms “substantially” and “normally” render the claimed subject-matter vague.

The Board then found the auxiliary request to be clear and remitted the case to the ED for further prosecution.

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