Tuesday, 5 April 2011

T 2292/08 – When Theory Meets Reality

The patent under consideration was revoked by the Opposition Division because the latter found the requests on file to lack sufficient disclosure. The Board does not agree:

[4.1] The invention defined in claim 1 of the main request relates to an article having loosely woven fabric layers that have a defined fabric tightness factor. The ground of opposition under A 100(b) raises the question as whether the patent discloses the invention in a manner sufficiently clear and complete for it to be carried out by the skilled person.

[4.2] A method for determining the fabric tightness factor is given in paragraphs [0026] and [0027] of the disputed patent. The equations given in paragraph [0026] include the parameters dw (width of warp yarn in the fabric) and df (width of fill yarn in the fabric).

The [opponent] made a fabric in accordance with Example 3 and measured the widths of the yarns in the fabric using an electron microscope. Calculating the fabric tightness factor on the basis of these measurements gave values above 1.3, which is in excess of the 0.6 indicated in example 3 and the range (0.3 to 0.6) defined in claim 1.

[4.3] It is thus apparent that either the examples given in the patent are not examples of the claimed invention, or there is something wrong with the method set out in paragraphs [0026] and [0027]. The examples are, however, quite clear in showing that, with the given material parameters, the alleged effect can be achieved; this tends to indicate that there is a deficiency regarding the disclosed method. The question is therefore whether the skilled person would readily notice the deficiency and how it would be corrected.

[4.4] The fabric tightness factor calculated by the [opponent] was above 1.3. A fabric tightness factor of 1.0 means that the measured cover factor was greater than the theoretical maximum, indicating that the fabric is jammed with yarns being compressed together. This result is clearly not in agreement with the basic teaching of the patent, whose purpose is to produce layers of loosely woven fabric (see paragraph [0009] of the patent specification), and also does not correspond to the appearance of the fabric actually produced by the [opponent].

Faced with such a curious result, the skilled person would immediately recognise that there was a problem concerning the way the fabric had been made.

[4.5] The [patent proprietor] has submitted extracts from textbooks (D8, D9 and D10) and declarations (D22 to D24), which show that it is well known in the art to use the theoretical diameter of the yarn when designing fabrics. This is because yarn woven into a fabric is distorted to such an extent that meaningful results based on actual measurements are difficult to obtain. Being well aware of the use of a theoretical diameter for the yarn, it would occur to the skilled person that by using this approach, rather than by measuring values, a more appropriate result in line with the teaching of the patent might be obtained.

[4.6] There is more than one way to calculate the diameter of the yarn. Although the results provided by the [opponent] in Table 3 of declaration D26 differ greatly, it was accepted by the [opponent] that these had been based on an incorrect calculation (see letter of 23 September 2010). The results calculated for example 3 (see Tables 1 and 2 of D26), although different, still fall within the claimed range. Unlike the results based on measured values for the diameter of the yarn, they are in line with the claimed invention.

[4.7] It would not amount to an undue burden for the skilled person to calculate the diameter of the yarn according any one of the equations put forward by the parties, as this means simply evaluating the data by a different equation, and does not involve the repetition of experiments to obtain more data, as was argued by the [patent proprietor].

[4.8] It is also clear that the degree of porosity of the yarn has a bearing on the estimation of the yarn diameter, and is determined largely by the factors referred to by the [opponent] (number of filaments in the yarn, cross-sectional shape of the filaments and construction of the yarn). The porosities of the fibers of the examples in the patent are not given, but a nominal value of 0.60 or 0.65 is commonly taken in practice for the purpose of calculating the yarn diameter. Since example 3 defines the linear density of the yarn (dtex), the only other variable that could have a significant influence on the diameter of the yarn is porosity. Should use of the typical values for porosity not lead to a fabric tightness factor within the claimed range, it would be a simple matter for the skilled person to calculate on the basis of yarns having a different porosity. So, on obtaining the unusual experimental values a skilled person would realise that the extremely high cover factor (and therefore the unrealistic tightness factor) could be corrected by choosing a yarn having an appropriate porosity value.

[4.9] The [opponent] has suggested that the different results of the various calculations lead to ambiguity at the limits of the claimed range, meaning that it is not possible to determine with certainty whether a particular woven fabric falls within the scope of the claim. Regarding this point, the [patent proprietor] referred to T 608/07, which considered that ambiguity at the edges of a claim is a matter for A 84, an article that specifically concerns the scope of the claims. A 83 and A 100(b) concern sufficiency of disclosure and, in the words of T 608/07, whether an ambiguity deprives the skilled person of the promise of invention. Given that it is possible for the skilled person to obtain the claimed ballistic resistant article, the alleged ambiguity does not give rise to a objection under A 100(b).


[4.10] In summary, faced with an unrealistic result, the skilled person would be alerted to an error in the method by which the fabric tightness factor is calculated using measured values for the yarn diameter, and would be aware that this can be corrected by using theoretical values instead, as is commonly done in the art.

The Board therefore considers that the patent specification contains sufficient information for the skilled person to carry out the invention.

To read the whole decision, click here.

The file wrapper can be found here.