The Guidelines (C-III 4.14) explain that “where a claim in respect of a physical entity (product, apparatus) seeks to define the invention by reference to features relating to the entity's use, a lack of clarity can result. This is particularly the case where the claim not only defines the entity itself but also specifies its relationship to a second entity which is not part of the claimed entity (for example, a cylinder head for an engine, where the former is defined by features of its location in the latter) […]”. Does this reasoning apply when a claim refers to a feature (such as a given frequency or wavelength) that is not inherent to the object itself? That is the question which T 564/07 and T 614/04 try to answer.
In T 564/07, Claim 1 of the application read:
A surface acoustic wave (SAW) identification tag, comprising: a piezoelectric substrate having a SAW transducer located thereon for generating a signal having a known frequency that travels down the substrate as a SAW; a number of reflectors […] arranged to reflect a portion of the SAW back to the transducer […], wherein for the known frequency each reflector is positioned at one of predetermined allowable positions, each allowable position being associated with a predetermined time shift and phase, wherein the phase has a phase step relative to a phase associated with an adjacent allowable position, to enable discrimination of overlapping reflected portions of the SAW.
[…] By specifying that each reflector is positioned at one of predetermined allowable positions and by defining said allowable positions by reference to a “known frequency” generated by the transducer, the relationship existing between adjacent allowable positions has been clarified in both independent claims 1 and 8.
Although these allowable positions do not constitute, as such, structural elements of the claimed tag, the relationship which is to exist between said positions leads by reference to concrete limitations as to the distribution of the reflectors on the substrate. It follows from the description that the distribution of the reflectors indeed constitutes the key element in order to permit discrimination between reflected portions of the SAW in case such reflected signals would overlap; such overlap would namely result from the proximity of reflectors in view of the pulse width of the signal generated by the transducer.
Although the “known frequency” or “given frequency” referred to, respectively, in claims 1 and 8 does not constitute an inherent feature of the transducer since the bandwidth of the signal generated depends, inter alia, on the interrogation signal generated by an external reader, the Board is satisfied that the requirements of A 84 EPC 1973 as to clarity are met.
As ruled in decision T 614/04 [2.4], concerning the examination of clarity, “the aspect whether a device having the concrete features of claim 1 and used with a wavelength not fulfilling the mentioned conditions falls within the scope of claim 1, is irrelevant during the examination of a patent application. [...] The Board considers that in an optical device comprising features dependent upon wavelength it is appropriate to introduce this dependence in a generalised way, e.g. by definition of a grating period as a function of wavelength...”.
Applied to the present case, this teaching implies that the fact that a tag having the concrete features of claim 1 could possibly be used with an external reader generating a signal with a frequency for which the relationship between the reflectors on the substrate and consequently the associated discriminating effect would not be provided, is not a valid criteria to justify a lack of clarity of the claimed subject-matter.
As stressed in decision T 614/04, it is essential that “if a predetermined wavelength is selected, the remaining features can be adapted to provide the required function...”, which is the case for the SAW identification tag of claim 1: the knowledge of the frequency permits to determine, for a selected phase step, the allowable positions and accordingly the position of the encoding reflectors. [3.1]
As the reasoning of the Board is essentially based on the findings of T 614/04, I had a look at this decision. It dealt with a rejection for lack of clarity concerning a reference to a predetermined wavelength:
[…] Claim 1 defines an optical device comprising inter alia a pair of low and high refractive index layers disposed on a multilayer mirror and a diffraction grating in the high refractive index layer. From mathematical relations indicated in the claim it can be derived that for a predetermined wavelength λ and suitable materials having at this wavelength a low and high refractive index, respectively, the period of the diffraction grating Λ is determined in dependence on the wavelength λ and the effective refractive index ne of the high refractive index layer for the polarisation mode for which the reflectivity of the multilayer is lowered. This is due to a phase shift of π occurring when this polarisation mode is coupled by the grating in the high refractive index layer […]. Therefore this definition is sufficiently clear for the skilled person to understand for which invention protection is sought. [2.1]
The ED agues in its decision that conditions in claim 1 to be fulfilled critically depend on the wavelength which is not part of the claimed subject-matter, and only apply to normal incidence. In this context reference was made to the Guidelines C-III, 4.[14]. Moreover, a claim for a device seeks protection for the device per se irrespective of the use to which it may be put. In the present case a device having the concrete features of claim 1 would fulfil the conditions in claim 1, when used with one wavelength, but not when used at other wavelengths. [2.2]
The Board however finds this argument unconvincing. The wavelength in the mentioned conditions serves to define the claimed device in terms of functional features. If a certain wavelength is selected, the remaining features can be adapted to provide the required function, i.e. the materials of the layers and the grating period can be chosen, accordingly. Expressed the other way round, for a completed device the appropriate wavelength can be determined. Normal incidence is implicit, since equation (2) in claim 1 does not contain a factor depending on the angle.
Point C-III 4.[14] of the Guidelines mentioned above is related to the “definition by reference to use or another entity”. It is stated there that a lack of clarity can result where a claim seeks to define an invention by reference to features relating to the entity’s use. This would particularly be the case where a claim not only defines the entity itself but also specifies its relationship to a second entity which is not part of the claimed entity. In contrast to that, the present claim specifies an optical device working at a predetermined wavelength, which is evidently not a use of the kind discussed in the Guidelines cited. [2.3]
In the Board’s view the aspect of whether a device having the concrete features of claim 1 and used with a wavelength not fulfilling the mentioned conditions falls within the scope of claim 1, is irrelevant during the examination of a patent application. A 84 requires that the matter shall be defined, for which protection is sought.
The Board considers that in an optical device comprising features dependent upon wavelength it is appropriate to introduce this dependence in a generalised way, e.g. by definition of a grating period as a function of wavelength as in the present case. Such a definition is evidently clear. It is in the present case also supported by the description, as is further required by A 84. Any other definition, e.g. based on absolute dimensions, would lead to undue restriction. [2.4]
To read the whole decision, click here.
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