T 0201/83 - Features taken from the examples / "Lead alloys" - #30

Citation rank: 30
No. of citations: 125

In T 201/83 the applicant requested an amendment, which limited an originally disclosed concentration range by replacing its lower boundary by a concentration value taken from an example. The Board had to decide whether this was allowable under Art. 123(2) EPC.

The amended claim read as follows: "Lead alloy comprising a small amount of magnesium and calcium, characterised in that the calcium content of the alloy is 690 to 900 ppm and the magnesium content 1 to 80 ppm".

The range of  l to 80 ppm for magnesium and the upper limit of 900 ppm calcium of the claimed alloy were originally disclosed as end-points of preferred ranges, the lower limit of 690 ppm calcium, however, was only disclosed in an example for a specific alloy (melt No. 8).

The Board observed that the basis for the suggested new lower limit was Melt No. 8. which contained 690 ppm calcium, but also 20 ppm magnesium and 0.39% tin. The question arose whether the calcium concentration could be taken from the example without also including the specific magnesium and tin concentrations in the amendment.

The Board analysed the effects of each of the alloy components and their interactions. The claimed lead alloys were useful as battery leads. In battery leads, small amounts of calcium are generally required, and small amounts of magnesium ameliorate certain problems (oxidation, corrosion of the lead) stemming from the added calcium. However, the two compounds serve different purposes; therefore an exact proportion between the two substances is not needed. Hence, the Board concluded that the connection between particular calcium and magnesium contents with regard to their effects were rather loose. The Board regarded them as design features that could be separately considered.

Specifically, they stated:

"This is rather like the choice of appropriate "resilient supports" for a device, wherein the applicant may, according to the Guidelines, restrict the claims to "helical springs" irrespective of the reasons for preference on the basis of drawings, where the same features were disclosed together with other features." (point 9 of the reasons)

The Board added, however, that this case was to be distinguished from other types of combination products where a particular choice of a limit for a parameter restricted the choice for another one:

"The invention is therefore different from other types of combination products where a particular choice of a limit for a parameter restricts the choice for another one, if substantially the same result is to be achieved. Had the choice of the concentration of one of these ingredients necessitated a particular kind of choice for the other, indicating a substantial degree of interdependence of quantitative values, the isolation of one value from the rest of the conditions could not have been readily envisaged." (point 6 of the reasons)

Given that there was only a loose connection between the concentrations of magnesium, calcium and tin in a lead alloys, and that the magnesium concentration could thus be independently chosen (within certain limits), isolation of the specific calcium content of melt No. 8 from the magnesium and tin content of that example was therefore held not to infringe Art. 123(2) EPC.

The Board thus remitted the case back to first instance with the order to examine the application on the basis of the amended claims

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Headnote:

An amendment of a concentration range in a claim for a mixture, such as an alloy, is allowable on the basis of a particular value described in a specific example, provided the skilled man could have readily recognised this value as not so closely associated with the other features of the example as to determine the effect of that embodiment of the invention as a whole in a unique manner and to a significant degree.

The full text of the decision can be accessed here.

Quotes from decisions citing T 201/83 can be found here.