Monday 16 April 2012

T 117/09 – Ashtray Revisited


The Guidelines, C-III 4.10, contain the famous “ashtray” example illustrating claim features consisting in results obtained by the claimed subject-matter:
“The area defined by the claims must be as precise as the invention allows. As a general rule, claims which attempt to define the invention by a result to be achieved should not be allowed, in particular if they only amount to claiming the underlying technical problem. However, they may be allowed if the invention either can only be defined in such terms or cannot otherwise be defined more precisely without unduly restricting the scope of the claims and if the result is one which can be directly and positively verified by tests or procedures adequately specified in the description or known to the person skilled in the art and which do not require undue experimentation (see T 68/85). For example, the invention may relate to an ashtray in which a smouldering cigarette end will be automatically extinguished due to the shape and relative dimensions of the ashtray. The latter may vary considerably in a manner difficult to define whilst still providing the desired effect. So long as the claim specifies the construction and shape of the ashtray as clearly as possible, it may define the relative dimensions by reference to the result to be achieved, provided that the specification includes adequate directions to enable the reader to determine the required dimensions by routine test procedures …”
The present decision on an appeal against the refusal of an application is interesting because it dwells on these notions.

Claim 1 of the main request on file read:
An antenna (100) comprising
  • a substrate (110) having a pair of oppositely directed surfaces,
  • a source plane conductor (120) on one of said surfaces having a signal line connected thereto,
  • a ground plane conductor (130) on another of said surfaces,
wherein said source plane conductor (120) is electrically isolated from said ground plane conductor (130),
characterized in that each of said conductors (120, 130) has a slot (122, 132) extending therethrough for controlling directional variation in intensity of radiation emanating from said antenna (100), said slots (122, 132) being different and being sized and positioned relative to one another to reduce said intensity of radiation in a rear direction extending from said source plane (120) toward said ground plane (130).
The Board found this claim to lack clarity:

[3.1] Claim 1 concerns an antenna comprising, as structural features, a substrate, a source plane conductor on one surface of the substrate having a signal line connected thereto, a ground plane conductor on another surface of the substrate, the source plane conductor being electrically isolated from the ground plane conductor, each of the plane conductors having “a slot” extending therethrough, the slots being “different”.

The claimed antenna is further defined by functional features. In particular, the slots are provided for controlling directional variation in intensity of radiation emanating from the antenna and are sized and positioned relative to one another to reduce the intensity of radiation in a rear direction extending from the source plane conductor toward the ground plane conductor.

[3.2] From a semantic point of view, the expression “a slot” implies that each of the plane conductors has at least one slot. Such an understanding is supported, from a technical point of view, by the embodiment of Figures 3B and 4B of the published application, according to which the source plane conductor has two slots (122b, 122c), whereas the ground plane conductor has a single L-shaped slot.


The Board notes that the appellant agreed with this understanding in writing […] and during the oral proceedings.

[3.3] The arguments produced by the appellant are not convincing.

[3.3.1] A 84 EPC 1973 requires that the claims define the matter for which protection is sought in a clear and concise manner and that the claims be supported by the description. R 29(1) EPC 1973 specifies that the matter for which protection is sought be defined in terms of the technical features of the invention.

These requirements serve the purpose of ensuring that the public is not left in any doubt as to which subject-matter is covered by a claim.

Moreover, these requirements imply that a claim must be non-ambiguous and comprehensible for a skilled person, and that a claim must identify all the essential technical features of the invention, these being the features which are necessary in order to obtain a desired effect. The claimed features may be expressed in structural or functional terms, the latter case applying if, from an objective point of view, the features cannot otherwise be defined more precisely without unduly restricting the scope of the claim, and if the functional features provide instructions which are sufficiently clear for the skilled person to reduce them to practice without undue burden (T 68/85 [headnote]). However, an applicant cannot simply define a technical feature as it wishes. Rather, the objectively more precise form must be chosen (T 68/85 [8.4.2]).

[3.3.2] In the present case, claim 1 of the main request results from a generalisation of the three disclosed embodiments (Figures 2; 3A, 4A; 3B, 4B; 3C, 4C).


The Board agrees with the appellant that the extent of protection should not be unduly limited. The Board also agrees that the claim may include structural and functional features. Nevertheless, the claim must clearly define the subject-matter for which protection is sought. In the Board’s view, this is not the case, as may be seen from the following paragraphs.

[3.3.3] As stated above, the expression “a slot” in claim 1 implies that each of the plane conductors has at least one slot. With this understanding, the feature that the slots are “different” causes a lack of clarity because the claim does not specify which particular slots on the source plane conductor and the ground plane conductor are indeed different. For example, the claim covers the case of plane conductors, each having an identical arrangement of different slots, wherein a given slot on the source plane conductor would differ or not from a slot on the ground plane conductor depending on which particular slots are considered.

In the appellant’s view, the slot patterns in the plane conductors were “different” in that the slots were non-identical and appropriately “sized and positioned relative to one another”.

This may be. The appellant’s argument, however, does not remove the ambiguity mentioned above concerning which combination of slots is being considered.

[3.3.4] In claim 1, the size and position of the slots are not defined structurally. They are defined instead by the effect of reducing the radiation intensity in the rear direction. The Board acknowledges the fact that a structural definition of the size and position of each slot of the patterns on the source plane conductor and the ground plane conductor would amount to an unduly limited extent of protection of the claim. However, the use of the expression “a slot” means that the claim covers innumerable arrangements of slots having any size and position, most of which are not at all envisaged by the description. Moreover, no evidence is provided in the application to conclude that all such arrangements would effectively permit the desired effect to be achieved. In other words, doubts exist as to whether this effect can readily be obtained for all of the possible arrangements of slots claimed. Although at least some arrangements of slots will undoubtedly give rise to the effect, in the absence of any indication of which slots have to be different and appropriately sized and positioned, the claim lacks clarity, notwithstanding its breadth.

[3.3.5] Even the claimed effect of reducing the intensity of radiation in a rear direction extending from the source plane conductor to the ground plane conductor lacks clarity, because it is not stated with regard to what the intensity of radiation is reduced.

[3.3.6] The example cited in the Guidelines, April 2010 (C-III 4.10) concerns an ashtray in which a smouldering cigarette end will be automatically extinguished due to the shape and relative dimensions of the ashtray. The latter may vary considerably in a manner difficult to define whilst still providing the desired effect. So long as a claim specifies the construction and shape of the ashtray as clearly as possible, it may define the relative dimensions by reference to the result to be achieved, provided that the specification includes adequate directions to enable the reader to determine the required dimensions by routine test procedures.

In this example, it is clear which structural features have to be appropriately designed in order to achieve the desired effect. The relative dimensions of the ashtray may vary, but will always be such as to automatically extinguish a cigarette.

In the present case, the specific structural features which have to be appropriately designed are not clear from the wording of the claim. With regard to a multi-slot antenna, no indication is given as to which of the many slots shall be designed so as to reduce rearward radiation intensity.

[3.3.7] With regard to the jurisprudence cited by the appellant, the Board agrees that essential features may be of a very general character (T 630/93), and that the breadth of a claim covering several possibilities (T 523/91; T 688/91) or of a term contained in a claim (T 238/88) do not necessarily impair clarity.

However, this jurisprudence does not invalidate the Board’s assessment mentioned above. In the present case, it is indeed possible to define the claimed subject-matter in clear terms on the basis of a generalisation of the embodiments of Figures 3A, 4A and 3C, 4C, which is supported by the description, entails a fair extent of protection and does not extend beyond the content of the application as filed (see claim 1 of the tenth auxiliary request).

[3.4] In conclusion, claim 1 of the main request does not meet the provisions of A 84 EPC 1973.

Therefore, the main request is not allowable.

Should you wish to download the whole decision, just click here.

The file wrapper can be found here.

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