T 1049/07 – Licence To Delete

When a claim as granted contains a misleading feature, can you eliminate it without infringing A 123(3)? In the present case, such an amendment was found to comply with A 123.

Claim 1 as granted read:

1. A substantially boron-free glass composition comprising the following by mole percent:

62-68% SiO2 / 2-6% Al2O3 / 10-16% Na2O / 0-6% K2O / 3-10% CaO / 0-8% MgO / 0-3% BaO / 2-6% ZnO / 0-2% TiO2 / 0-2% F2

wherein the total amount of Na2O and K 2O is less than 18 mol% and wherein the composition further contains Li2O in an amount no greater than 8 mol% and in an amount sufficient to render the HTV of the glass composition between about 1010°C (1850°F) and about 1204°C (2200°F), the liquidus temperature of the glass composition being at least 139°C (250°F) below said HTV, said HTV being defined as the temperature at which glass viscosity is 100 Pa•s (1000 poises).

Claim 1 of the request as maintained by the Opposition Division (OD) read:

1. A substantially boron-free glass composition comprising the following by mole percent:

62-68% SiO2 / 2-6% Al2O3 / 10-16% Na2O / 0-6% K2O / 3-10% CaO / 0-8% MgO / 0-3% BaO / 2-6% ZnO / 0-2% TiO2 / 0-2% F2 

wherein the total amount of Na2O and K2O is less than 18 mol% and wherein the composition further contains Li2O in an amount no greater than 8 mol%, the glass composition having an HTV of between about 1010°C (1850°F) and about 1204°C (2200°F), the liquidus temperature of the glass composition being at least 139°C (250°F) below said HTV, said HTV being defined as the temperature at which glass viscosity is 100 Pa.s (1000 poises).

The opponent filed an appeal and pointed out that this claim violated A 123(3). The Board does not agree:

[1.2] The [opponent] held claim 1 as maintained in the contested decision to contravene A 123(3).

In this respect, it argued that the feature:

“the composition further contains Li2O in an amount no greater than 8 mol% and in an amount sufficient to render the HTV of the glass composition between about 1010°C (1850°F) and about 1204°C (2200°F)”

in granted claim 1 had been replaced in claim 1 as maintained in amended form by the following allegedly non-equivalent feature reading: 

“the composition further contains Li2O in an amount no greater than 8 mol%, the glass having an HTV of between about 1010°C (1850°F) and about 1204°C (2200°F)”.

Consequently, claim 1 as maintained encompassed compositions which were not covered by claim 1 as granted, in particular compositions containing almost no Li2O and wherein the HTV parameter was regulated by other oxides such as Na2O.

It argued in particular that in claim 1 as maintained the amount of Li2O could be chosen freely between 0% and 8 mol%, whereas in accordance with claim 1 as granted, the amount of Li2O was functionally linked to the achievement of an HTV in the claimed range. Hence, it had necessarily to exceed the lower limit of 0%. Consequently, claim 1 as granted excluded glass compositions having 0% Li2O, whereas the claim maintained by the opposition division allowed such compositions. The scope of protection conferred by the claims had thus been extended.

[1.3] The board does not share the [opponent’s] view for the following reasons.

[1.3.1] According to A 123(3),

“the European patent may not be amended in such a way as to extend the protection it confers”.

Therefore, in assessing whether claim 1 at issue meets the requirements of A 123(3), the extent of protection conferred by claim 1 as granted has to be compared with that of claim 1 as maintained.

[1.3.2] In the present case, it is observed that both claims under dispute (i.e. claim 1 as granted and as maintained) contain the feature “the composition further contains Li2O in an amount no greater than 8 mol%”. Although a lower limit is not explicitly stated in the claim(s), this feature clearly indicates that Li2O is a mandatory constituent. As a logical consequence, in both glass compositions claimed the lowest possible amount of Li2O cannot be zero, as alleged by the [opponent].

As regards the lowest possible amount of Li2O in claim 1 as maintained, the board - in the absence of any convincing counter-argument - accepts the respondent’s argument that this amount has to be set as being “above the analytical detection limit for Li2O”.

In claim 1 as granted, the amount of Li2O is not only defined as being “no greater than 8 mol%” - as in claim 1 as maintained - but also as being “sufficient to render the HTV of the glass composition between about 1010°C (1850°F) and about 1204°C (2200°F)”.

The board recognises that on reading this claim version, the skilled person might be misled to assume the presence of an exclusive functional link between the amount of Li2O in the glass composition and the HTV being between about 1010°C and about 1204°C. However, the study of the description - which in the present case is necessary for the detailed assessment of the extent of protection of this claim - reveals that no such link (or at least not an exclusive one) in fact exists, for the following reasons.

Although paragraph [0027] of the patent in suit indicates that Li2O acts as a glass viscosity reducer, it can be seen from paragraphs [0023], [0024] and [0025] that Li2O is not unique. Other components, such as fluorine, TiO2, CaO and MgO, are also disclosed as having this property of reducing glass viscosity. Since Li2O is thus not the sole viscosity-reducer in the glass composition claimed, it is impossible to estimate its contribution to the viscosity and what the contribution of the other components is. For the same reason, it is impossible to assess whether Li2O contributes to the high temperature viscosity (HTV) and what that contribution is.

In fact, the contested patent itself confirms that Li2O does not automatically lead to an HTV of between about 1010°C and about 1204°C, since Example 1 of the contested patent discloses a glass composition not containing Li2O but having a HTV within that range.

[1.3.3] For the above reasons, the board is convinced that the patent has not been amended in such a way as to extend the protection it conferred in its version as granted.

Therefore claim 1 as maintained, and independent claims 6 and 12 - amended in the same way as claim 1 - fulfil the requirements of A 123(3).

Strange, isn’t it?

Anyway, it is interesting to see that the feature “in an amount no greater than 8 mol%” is understood to exclude an amount of 0 mol%. That the minimum amount is set to be equal to “the analytical detection limit” is somewhat problematic as it will necessarily change as a function of the progress of analytical methods.

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