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Ruling out the prior art

28 January 2015

The EPO Board of Appeal decision T 1488/10 examines whether or not a feature in a figure of a prior art document can be measured to assert that a claim is not novel, if the figure appears to be to scale.  

Previous case law on this matter generally indicates that schematic drawings, unlike construction drawings, are not considered to be exact representations and would not be used by a person skilled in the art to determine dimensions. According to the case law, a schematic drawing can be used to infer relative sizes of components, for example, to show that one component is larger than another, but cannot be used for anything that would require accurate measurement, such as calculating a ratio between two components.

The case was interesting in that although the cited prior art document included a schematic drawing, unusually the schematic drawing specified the dimensions of certain parts, but not the part that was critical to the case.  The Board had to consider what the skilled person would infer about the critical part within the context of a partially dimensioned schematic drawing.

Disagreeing with the Examining Division, the Board concluded that the inclusion of the dimensions of some parts does not mean that the entire drawing is to scale. Therefore, for this case, the critical part of the prior art document could not be measured to prove a lack of novelty.

In more detail, the application related to an ultrasonic horn assembly with a connector, wherein the relative length of a section of the connector was an important feature. The Examining Division cited prior art document D3, which they asserted directly and unambiguously discloses this feature (see component 85 of Figure 4 of D3, shown below).

Figure 4 is a schematic drawing, but dimensions L1, L2 and t are shown.  However, no indication is given of the dimensions of component 85.  As some of the dimensions are shown, the established distinction between schematic drawings and construction drawings does not apply as clearly and the question then became, does the inclusion of the dimensions of a feature of the figure indicate that the entire figure should be considered to be to scale, and can be used as a prior art disclosure of a dimension ratio?

The ratio of L2/L1 as measured from Figure 4 corresponds with the described ratios of L2/L1 in the description of D3.  In view of this, the Examining Division concluded that the relative dimensions shown in Figure 4 conformed to the relative dimensions of the real device, i.e., the drawing is to scale, and is therefore a novelty destroying disclosure.

The Board of Appeal agreed that L1 and L2 were represented in such a way in Figure 4 that the ratio of their lengths was in accordance with the description of D3.  However, they made the point that the dimensions L1, L2 and t are only shown in Figure 4 to indicate the size of the “front mass” 82 and “slits” 82a, which are important to the invention in D3.  As the other parts, including component 85, are not given dimensions, and not described as having dimensions with any specific significance for the invention, the Board of Appeal concluded that the dimensions of the other parts might not be reliable, and should be distinguished from L1, L2 and t.

The Board of Appeal came to the conclusion that the dimensions of these other parts could have been intentionally distorted by the draughtsman when creating the figure, for example to increase the clarity and visibility of the important components in the figure. This would mean the represented dimensions of the component in question, in this case component 85, may not correspond to its actual dimensions. Accordingly, the Board of Appeal concluded that dimensions obtained by measuring the schematic drawing shown in Figure 4 do not form part of the disclosure of D3, and therefore D3 cannot be considered to be novelty-destroying prior art.

Ultimately this case serves as a reminder to follow best drafting practice.  If the dimensions of a component are important, ensure they are included in the description, along with preferred ranges. If a drawing is intended to be to scale and could be used as a construction drawing, this should be clearly stated in the description.  This allows the applicant the best chance of relying on a drawing as prior art against later applications.


Jack Whitfield
Advanced Engineering group

If you require further information on anything covered in this briefing, please contact Jack Whitfield (; +44 114 273 3400) or your usual contact at the firm.

This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Withers & Rogers LLP, June 2015