Monday, 17 May 2010

T 143/07 – The Draughtsman’s Freedom

Is it possible to base amendments of claims on features that are found in drawings only? No, say the French courts. Yes, says the EPO (e.g. T 169/83). But even the EPO does not accept any amendment just because the feature may appear in a drawing. The Guidelines C-VI 5.3.2 state that “care should be taken when amendments are based on details which may only be derived from the schematic drawings of the original application. The manner in which a particular feature is depicted in the drawings may be accidental”. The present decision comes to a similar conclusion, although via a detour: by invoking a mysterious person very seldom encoutered in the caselaw: the draughtsman.

The patent as granted claimed a probing member (90) for use in an apparatus for determining surface topology of a teeth portion, […] in the form of an elongated transparent body having a front face, and end mirror (95), and top, bottom and side walls extending therebetween […], said front face being inclined relative to said top wall so as to ensure that light beams incident on the front face perpendicularly thereto impinge said top wall at an angle providing their total internal reflection therefrom and further bouncing, by means of total internal reflection, between the top wall and […] the bottom wall towards said end mirror (95) to be redirected thereby […].

The Opposition Division (OD) revoked the patent. It found that the structure and the function of the feature “light beams incident on the front face perpendicularly thereto” as such was not clearly, unmistakably and fully derivable from the schematic figures 2A and 2B as filed because: no incident light beams were represented in the figures 2A and 2B; no symbolic indication was given for a perpendicularity of the beams (99) in the figures 2A and 2B; the measurement of the schematic figure 2B did not precisely lead to an angle of 90°; and only light rays which bounce off the walls of the probing member at an angle in which the walls are totally reflective and finally bounce onto mirror (94) and reflect from there out through the sensing face (97) for a particular but unknown incidence angle were disclosed. Finally, no explicit indication was given in the rest of the application as filed to support the view that the given angle should be 90°.

The patent proprietor filed an appeal. It pointed out that the figures were “constructional-like” rather than schematic and that the skilled person would have derived the claimed feature from the drawings.

Here is what the Board had to say:

[2.1] The parties did not disagree with the OD that there was no explicit disclosure in the description and claims as filed of the feature “so as to ensure that light beams incident on the front face perpendicular thereto impinge said top wall at an angle providing their total internal reflection”. The board will refer to this feature as the “perpendicularity feature” in the following.

[2.2] Turning to the disclosure of the drawings, in particular Figures 2A and 2B of these Figures, particularly Figure 2B, light rays inside the probing member [90] and exiting therefrom are, to use the wording of the description, “represented schematically”, but “light beams” incident on the front face are not represented at all, which is consistent with the description of Figure 2B […] reciting “depicting also some exemplary rays passing therethrough”. In other words, the drawings too provide no explicit disclosure of the “perpendicularity feature”. Of course, there must be some incident rays, the board concluded that the OD was correct in considering there is a disclosure thus of incidence of the rays but not of angle of incidence.

[2.3] In the board’s view, a significant disclosure is contained in the original documents […], namely “Three light rays are 99 are represented schematically. As can be seen, they bounce at the walls of the probing member at an angle in which the walls are totally reflective and finally bounce on mirror 94 and reflected from there out through the sensing face 97.”

[2.4] As the incident rays onto the probe are not mentioned, this explicit disclosure is just what the draughtsman represented in Figure 2B […] and is also consistent with the description of the drawings “light rays passing therethrough”. An element of draughtsman’s artistic freedom or licence is, in the view of the board, involved in portraying the ray paths shown in Figure 2B. The draughtsman had only to illustrate the bouncing on the walls then mirror and exit from the probe, choosing to show the latter as a straight line. The incident ray path was left open. The board therefore considers the refracted ray path actually shown in the probe as not to be a reliable indication of the angle of incidence.

In a way, the [patent proprietor] confirms this assessment of draughtsman’s artistic freedom or licence of the draughtsman by referring to the Goldmeier effect that small angles cannot be differentiated by the human eye, i.e. implying the path shown is unreliable, and to “assuming perpendicular incidence”, i.e. the draughtsman left it out.

[2.5] Significantly, there is no teaching at all in the description, of how the paths shown give an indication that the relationship between the wedge angle and perpendicular incidence is pertinent to meeting the bouncing and exiting constellation as set out in point [2.3] above. The situation concerning this relationship is not therefore unlike that set out, for instance, in decision T 666/07 [3.4] – “... relationship introduced ... has been singled out from amongst equally feasible other features, which selection is an arbitrary one as there is no basis for it in the originally filed application ...”.

[2.6] The board cannot therefore agree with the [patent proprietor] that the skilled person would draw any conclusion about the relationship between wedge angle and perpendicular incidence as applied to the path through and exiting the probe. In fact, the approach of the [opponent] appears persuasive in arguing that the skilled person would simply ensure the angle of the ray impinging on the top wall is smaller or the same as the critical angle and the inclination range of incident angle on the front face takes account of refraction. Thus, even if the board accepts the interpretation of decisions T 261/90 and T 748/99 (sic) advanced by the [patent proprietor], i.e. the drawings are constructional like drawings in relation to wedge angle which can be seen to be more than 45°; this does not imply any disclosure beyond that argued by the [opponent].

[2.7] Supposing, arguendo, that the Figures are taken to give a specific teaching of ray path, then since Figure 2B does show a slightly off-perpendicular refracted ray path in the probe, this is what the skilled person is taught. While, as the [patent proprietor] argued, there are many possible angles of incidence, there is no reason in the documents as filed with the wedge angle drawn then to consider any refracted ray path other than that disclosed as necessary to provide the path through and exiting in a straight line from the probe exactly as shown. In particular, the wedge angle does not define perpendicular incidence in the drawings. Where is then the direct and unambiguous disclosure that the angle of incidence is modifiable with the knock-on effect of changing the path through the probe and exit angle?

Thus, while the board would not dispute that the skilled person could, as a kick-off criterion, choose perpendicular incidence and dimension the probe accordingly, this choice is simply not disclosed in the documents as filed.

Similarly, even if the skilled person can deduce that the wedge angle shown is greater than 45°; this still offers no reason to modify the ray path. Whether the probe would be larger for off perpendicular incidence may play a role for instance in respect of fitting and space criteria, but it does not compel the skilled person to assume perpendicular incidence nor to add the missing disclosure to the documents as filed. […]

[3.2] The board can only concur with the remark of the [opponent] at the oral proceedings that the disclosure simply does not go far enough to provide the reference to perpendicular.

As a consequence, the Board rejected the request on the ground of non compliance with A 123(2).

To read the whole decision, please click here.