Dimensions from patent drawings

EPO decision T 1488/10 considers a new twist on a hoary old question: can one rely on measurements taken from a prior art drawing to invalidate a patent? The twist in this case was that the drawing in question had some measurements indicated for the device shown, just not the particular ones that were needed to invalidate the claim under attack.

If an inventor claims in a patent application that the length of the secondary doohickey is at least three times the sprocket pitch diameter, it can be hard to prove lack of novelty because there may be considerable difficulty in finding a piece of prior art that expressly discloses the same dimensional constraints.
Which line is longer? Sometimes you really
do need to take a ruler to the drawing.

Frequently therefore, an examiner or opponent who is unable to find the necessary lengths or their ratio described expressis verbis in a prior art reference, has taken a ruler to a prior art diagram and shown that a sufficiently lengthy secondary doohickey was visible alongside an appropriately miniscule sprocket. Should such measurements be regarded as part of the prior art disclosure?

The basic rule at the EPO is that stated in T 204/83 (OJ EPO 1985, 310):
Features shown solely in a drawing form part of the state of the art when a person skilled in that art is able, in the absence of any other description, to derive a technical teaching from them. Dimensions obtained merely by measuring a diagrammatic representation in a document do not form part of the disclosure.

In T 1664/06 the Board followed the same path, refusing to take accurate measurements from a drawing, and distinguished over T 748/91 in which a schematic drawing was relied on simply to infer that one dimension was evidently larger than another.

In decision T 451/88 a distinction was drawn between scaled construction drawings and the schematic drawings conventionally included in patent documents, the latter not being intended to allow manufacture of the product, and it being held (once again) that schematic drawings could not be used to derive a ratio between two dimensions.

So we have a rule that pure schematic drawings cannot be accurately measured, while scaled construction drawings can. But what about a drawing where some of the illustrated components carry information about their dimensions? Does this indicate that the drawing is to scale?

T 1488/10
In this latest decision, the prior art drawing below was at issue. The IPKat has reproduced the drawing and has added some cheery colours, at no extra cost above and beyond your usual monthly IPKat subscription.

There is a connector, shown in yellow, which is threaded top and bottom to the green and blue components. So the yellow connector can be notionally divided into three segments along its length: the upper and lower "clamped" portions, and the middle segment which is "free of connections" (in the words of the patent application under attack).

The prior art drawing: if L1 and L2 are known, what does
this tell us about the yellow connector's dimensions?
The novelty of the claim turned on the feature that "the segment of the connection which is free of connection constitutes between 50% and 75% of an overall length of the connector." A ruler measurement of the prior art drawing showed that the relevant segment constituted about 66% of the overall length, slap bang in the middle of the claimed range. The Examining Division refused for lack of novelty on this basis, despite being fully aware of the general rule that one should not take measurements from schematic drawings.

The reasoning of the Examining Division was that the general rule in T204/83 did not apply, as that decision was only concerned with features "shown solely in a drawing". If you look again at the drawing above you will see two lengths, L1 and L2 in red. Although not directly related to the length of our yellow connector, they are dimensions along the same axial direction, and the description of the document required that they be in a ratio of between 1:2 and 1:3 (in the drawing they are 1:2). The Division reasoned therefore:
Since Fig. 4 shows that L2 = 1/2 * L1 and because it is indicated in [0026] that L1 = 23mm and L2 = 12mm, it can be concluded that, at least in the longitudinal direction, the relative dimensions as shown in Fig. 4 can be considered as conforming to the relative dimensions of the real device.
In other words, the inclusion of actual dimensional constraints on a schematic drawing, especially along the same directional axis, were considered to transport that drawing from the schematic realm into the real world, and the drawing could be regarded then as dimensionally accurate.

The Board disagreed on appeal. After discussing the meaning of L1 and L2 (and also of the other indicated dimension, t) and the fact that these parameters were important to the performance of the apparatus being described, the Board turned to the components whose length was neither indicated in the drawings nor discussed in the description of the prior art document [Reasons for the Decision, 3.5]:
However, the dimensions of the other parts of the ultrasonic transducer shown in Figure 4 have to be distinguished from L1, L2, and t. First of all, they are not referred to by any reference signs in the Figure. Furthermore, they are not described as having any specific significance for the claimed invention. For example, no advantages are mentioned in the description concerning particular choices of the dimensions of these other parts.
Regarding the representation of the dimensions of these other parts of the device, factors like the clear visibility in the Figure of these parts may well have induced the draughtsman to represent their dimensions in a manner that does not correspond to their actual dimensions. Therefore, in relation to these other parts of the ultrasonic transducer, the board is of the opinion that dimensions obtained merely by measuring the schematic drawing in Figure 4 does not form part of the disclosure of document D3 (see T 204/83, point 7 of the Reasons).
Accordingly, the relative dimensions of the length of the stud 85 and the length of the connection-free part thereof, as obtained by carrying out measurements on Figure 4 does not constitute part of the disclosure of document D3. Hence, feature (ii) of claim 1 of the main request has not been disclosed in document D3.
While the IPKat thinks the decision is legally correct (and isn't that what matters?), and that any other decision would have been a poor precedent, he wonders what the inventors behind document D3 might have thought about the contention that they did not disclose a connector free from connections along 66% of its length. Anyone who has drafted a decent number of mechanical cases will get a feel for drawings that are dimensionally more-or-less accurate as opposed to purely schematic illustrations, and the figure illustrated above has the feel of being the former.

It also seems unlikely, given the uncrowded arrangement of components, that requirements of clear visibility would have necessitated the draftsman lengthening or shortening the connector to any major extent. But here we are entering the realm of speculation. The bottom line is that to invalidate a patent for lack of novelty you need a clear and unmistakeable disclosure of all claimed features, and so the Board got it right in terms of the standard of disclosure required.

In the end, the victory for the applicant on this point was Pyrrhic: although D3 did not anticipate, all of the claim sets were held to be obvious over another document entirely.
Dimensions from patent drawings Dimensions from patent drawings Reviewed by David Brophy on Wednesday, November 12, 2014 Rating: 5


  1. In T0115/12 the Board of Appeal recently upheld the first instance decisión in which the Opposition División allowed an amendment consisting of the addition to claim 1 of a feature relating to the length of a slot. The description was silent on the length of the slot. The amendment was based on the drawings as interpreted by the person skilled in the art. (The written decision has not yet been sent out.)

  2. Feelings are subjective, I think we are in trouble if we resort to how one "feels" when interpreting prior art. In this instance, I believe the decision is correct. In any event, who's to say part '87' isn't intended to be 100cm long? Why should my interpretation be deemed ridiculous if I 'feel' it's correct?

    If things are really that close, I think you will struggle under inventive step...and if you can't make a good case that the claims aren't inventive, do something else, find better prior art, redesign around or take the risk and leave it up to the courts to decide if you infringe or not.

  3. Think about the basic purpose of patents.

    As a person skilled in the art what can I reproduce from the teaching of D3?

    If I had made an actual object to the exact dimensions as measured from these drawings it would have invalidated the patent. I would argue that is the FIRST thing you would consider doing to test the invention.

    So we have an ineffective technical teaching in a drawing in a document to remove validity but a perfectly clear and effective teaching in the same drawing as how to make a physical object that would invalidate.

    Now that's clear.

  4. The FIRST thing I would do is understand the actual law in the patent world, which recognizes that drawings are NOT to be scaled as you would FIRST do.

    The SECOND thing I would do is make sure any engineers I hire are smart enough to understand the rules of the game and NOT make such a foolish mistake.

    1. It's not what I would do. Like you I live in the Patent World. The Engineer would do that and what has patent law got to do with technical disclosure. What would you do about the Engineers you do not hire? Come out of Patent World and live in the Real World. You clearly have never worked with an Engineer.

  5. I agree with Anon of 12:06 GMT. Even if it is not apparent whether the drawings of D3 are scale drawings (though it looks like they probably are), if the skilled person were to follow the teaching of D3 religiously, including making something as shown the drawings, then they would have ended up with something that anticipates the later claim. It isn't a good feeling that such a disclosure doesn't anticipate the later claim.

    Even if one could wriggle out of a novelty attack, surely D3 would anyway have a good chance of taking away the inventive step of the later claim? Starting from D3, which includes the drawings, the difference between the later invention and the prior art is that the ratio between the unclamped and clamped length of the yellow piece is "unknown" in the prior art. Other that that, they're apparently the same. The technical advantage? For the sake of argument, as per the patentee's submission. The technical problem? The inverse of the advantage. Would it have been obvious, starting from D3, how to solve that technical problem? Well, the drawings provide a blooming great clue as to some dimensions that might be used as a starting point... they look a bit like engineering drawings, so the skilled person might very well say "let's start with that and see how it goes". And lo and behold, they make something vaguely to the dimensions of D3, and problem solved!

    If not novelty, then the patent has to be bad on inventive step. It looks like it was considered bad on inventive step, but over document other than D3.

  6. People complain about the strictness of the EPO position on Art 123(2), added matter. But it is simply the other side of the coin from novelty.

    So, anybody who, here, thinks that novelty is not destroyed has no business asserting that the EPO is too strict when it comes to Art 123(2).

    Keep in mind that this was an EPO TBA operating in ex parte proceedings, with no Binding Precedent effect to worry them, and knowing that they are going to find the claim obvious anyway.

    In inter partes proceedings, post issue, there would have been an Opponent to make the case made above by Anon at 12:06 hr. I think it might have been enough to win the point.

  7. Would the prior art document be enabled if the engineer couldn't replicate the invention by imitating the dimensions of the patent figures(assuming as here that the specification is otherwise silent as to the ratio). Should we not presume unless evidence or common sense indicates otherwise that a prior art application is enabled?

  8. The current case law should prompt mechanical patent practitioners to include dimensions/ratios (absolute and ranges) etc. in the specification not only for fallback claiming positions, noting the likelihood of this imparting at least novelty to the claims if added, but also to prevent others getting a later-filed patent based on those dimensions/ratios. Moreover, for the same reasoning, if scale drawings are being used in the patent application (not untypical in my experience), it would be worthwhile to explicitly state this, maybe with a statement to the effect that an embodiment of the invention is to the scale as shown.

  9. Is there an EP equivalent to the US 37 CFR 1.84 (k) Scale.

    "The scale to which a drawing is made must be large enough to show the mechanism without crowding when the drawing is reduced in size to two-thirds in reproduction. Indications such as “actual size” or “scale 1/2” on the drawings are not permitted since these lose their meaning with reproduction in a different format."

  10. In addition to the CFR level, the US also has the MPEP level.

    See http://www.uspto.gov/web/offices/pac/mpep/s2125.html

    Clearly, if any figure is not marked "to scale" no one (either engineer or attorney) should - and a I daresay would - ASSume that one could scale the figure.

    (and yes, I did work with engineers, and was an engineer for nearly fifteen years before switching careers into patent law)

  11. I don't like the reasoning of the Divsion. But I wonder whether the measurements of the drawing really are unsuitable for the purpose of novelty.

    D3 objectively does disclose the drawing. It seems to me that the drawing, including its dimensions, make technical sense. It therefore would seem to represent one very specific embodiment of the invention of D3. If that very specific embodiment falls within the scope of the claim, that would seem to give a lack of novelty. So I also agree with the anonymous of 12:06.

    The situation is different if one would try to use certain dimensions of the drawing as a basis for a claim amendment (obviously assuming the drawing is part of the application documents and not part of a prior art document). That would almost always lead to an unallowable intermediate generalisation, as the drawing only discloses that very specific embodiment and does not tell the skilled person that certain dimensions can be extracted and/or generalised. And the drawing is also not sufficiently precise to extract something like "2:3" or "66%" or "about 66%".

    An attempt at an analogy. Suppose the "description" consists of a particular physical embodiment of the invention. It would be really hard to base a claim on that without infringing Art. 123(2). But such a physical embodiment would clearly be excellent prior art for a novelty attack.

  12. I don't suppose it was relevant in the case under consideration, but it can be worthwhile checking the accuracy of the formal drawings, especially in cases that you have taken over from a third party (of course I always used to diligently check those of my own cases: really!). I have sometimes overcome seemingly unanswerable objections by referring back to the formal drawings where errors had lead to prima facie anticipation based on the formal drawings.

    I think that the issue of whether it is legitimate to take dimensions from drawings is affected by the technology. My experience has been that the patent drawings of a mechanical device were normally derived from an actual physical item or engineering drawings (but not invariably, one application being based on a rough sketch made by the inventor on a paper napkin), whereas cross-sections of semiconductor structures were generally highly schematic, showing only the topography of the various layers rather than their physical proportions.

  13. So, ladies and gentlemen, from Board 3.4.03 in this Decision, a subtle distinction between novelty and obviousness, when it comes to the prior art effect of Doc D1 on Parameter X in the claim in view.

    I think this distinction is of much wider applicability than just to dimensions in drawings.

    We know already that, if, in following the instructions given in D1, it is inevitable that you include X, it's a matter of novelty.

    Conversely, we now know (Reasons, 6.3) that if it is "natural to choose" X then, although novelty is not prejudiced, D1 renders the claimed subject matter obvious.

    Is the distinction real, and is it useful?

  14. "...it can be hard to prove lack of novelty because there may be considerable difficulty in finding a piece of prior art that expressly discloses the same dimensional constraints"

    In which case, such a claim is novel, is it not?

    Prior art doesn't have to disclose such wording/constraint, but an example falling within such definition would be sufficient.

  15. I think Max Drei's first comment hit the nail on the head:

    "Keep in mind that this was an EPO TBA operating in ex parte proceedings, with no Binding Precedent effect to worry them, and knowing that they are going to find the claim obvious anyway."

    Reading between the lines of the decision, it's clear that the Board were able to take a hard line on novelty over D3, safe in the knowledge that they were refusing anyway over other prior art.

    It would have been very interesting had there been no other prior art. Then they would have been forced to follow through on their D3 analysis, and to take a position on whether it was obvious to follow the dimensions of the D3 drawing as a reasonable starting point (arguably the only logical starting point) for implementing D3. It's difficult to see how the claim could not be found obvious since the only guidance as to the length of the connector is the drawing itself.

  16. Thank you David Brophy. The "No Binding Precedent" point is for me important. It gives EPO Boards the freedom to pick and choose how to get to the end result they feel in their Waters is the "right" one. Equally (of course) they enjoy the freedom the freedom to ignore any other points that don't "fit" with the way they are heading, or which are just too delicate, unripe, contentious, problematic, or tedious, to address in their writen Decision.

    For example, Prior use. How many times has that been the "killer" validity attack, yet not fully addressed in a written Decision which revokes on other more dubious grounds?

    A possible parallel here with what's going on currently in the USA, with business method claims challenged on validity? Because it is so hard to get them revoked for obviousness, they are getting revoked for want of eligibility.


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