T 0422/00 03-07-2003

Reasons for the Decision

1. The appeals are admissible.

The interventions are also admissible because the notices of intervention were given within three months of the date on which the respective infringement proceedings were instituted (Article 104(1) EPC first sentence).

2. Since, in the patent application as originally filed the hydraulic diameters were expressed in "inches", this unit is used in the present decision without added conversion to SI units.

According to Article 85 EPC, the abstract shall merely serve as technical information and should not be taken into account for any other purpose. Therefore, the fact that the upper limit of 0,07 inches was mentioned in the abstract of the patent application is irrelevant for the present case.

3. It is not disputed that, in the course of proceedings, a feature which can be clearly and unambiguously derived from a drawing can be used to define the subject-matter for which protection is sought. In the course of the examination proceedings, this can result in a broadening of a numerical range expressis verbis given in the original disclosure without necessarily contradicting said disclosure and without offending against Article 123(2) EPC; it depends on the circumstances of each case.

4. In the decision under appeal, the first instance held that, since the curves B in Figure 3 are "higher" than the prior art curves at least up to a value of 0.07 inches, the skilled person would conclude that the invention, as far as heat exchanger cores corresponding to the curves B are concerned, should extend up to 0.07 inches.

5. In the application as originally filed of the patent in suit, after an introduction setting out the problems which occur in condensers employed in air conditioning or refrigeration systems, a summary of the invention is presented on page 2, which provides the information that each of the fluid flow paths defined in the condenser tube has a hydraulic diameter in the range of about 0.015 to 0.040 inches. The same information is given in the detailed description of the preferred embodiment of the invention, page 7, first lines, immediately followed by the indication that "a hydraulic diameter of 0.035 inches optimizes ultimate heat transfer efficiency and ease of construction". Then, on page 9, the last sentence relating to Figure 3 has the following wording:

"As can be appreciated from Fig.3 , heat transfer is advantageously and substantially increased in the range of hydraulic diameters of about 0.015 inches to about 0.040. inches through the use of the invention with some variance depending upon air flow". As seen, here, the range is given in connection with the disclosure of Figure 3.

Finally, this range is also given in each of the three independent claims 1, 4 and 9, as originally filed. Thus, in six passages of the patent application as originally filed, the range of 0,015 to 0,040 inches is given expressis verbis, and there is no suggestion that other limits could be considered or envisaged, in particular the claimed upper limit of 0.07 inches when in Table 1 of the description an hydraulic diameter of 0.07871. inches for the prior art is given.

6. As support for the claimed upper limit of 0.07 inches, the respondent essentially relies on the disclosure of Figure 3 and, in particular, on the curves B of this figure. Figure 3 is one of four figures, namely Figures 3 to 6, which are all in Cartesian coordinates, these figures - according to the description - aiming at showing a number of advantages of the invention. In Figure 3, the heat transfer rate (Y-axis) is plotted against the hydraulic diameter (X-axis) at air flows varying from 450 to 3200 standard cubic feet per minute ("SCFM" in abbreviated form). The abscissa axis is divided by pairs from 0.00 to 0.18 inches. The left part of Figure 3, which is headed "INVENTION", shows two sets of graphs, namely.

- a first set of four graphs A in plain lines, one above the other, for four different air flows, said graphs extending from the area between 0 and 0.02 inches to the area between 0.06. and 0.08 inches and presenting rather pronounced apices at about 0.02 inches; and

- a second set of four graphs B in broken lines for the same air flows, however with their left ends in the area around 0.04. inches and their right ends between 0.06 and 0.08 inches, as are the right ends of the curves A; these graphs B are a bit domed or flat with their higher points near 0.04 inches and they each lie respectively above the right parts of the graphs A.

The right side of Figure 3, which is separated from the left side by a blank part, concerns the "PRIOR ART", namely condenser cores previously produced by the applicant, and it shows four rather horizontal curves in dashed lines for the same different air flows. According to the description, the curves A and B were generated by computer, based on a heat transfer model for two condenser cores having the same face area and being made according to the present invention, several common constructional specifications of these cores being given in the description. The core according to the curves B differs from that of the curves A only by the fact that the length of the flow path in each tube was doubled, i.e. the number of tubes was halved and the tube length doubled. In the description, it is also mentioned that various points on the curves A and B have been confirmed by actual tests, however without further details.

7. An examination of the curves shows the following:

The value 0.07 inches neither appears on the abscissa axis of Figure 3, nor is suggested by a particular point or mark on any graphical representation of this figure. The right ends of the curves A and B, which according to the appellant, disclose this value, do not end on a clear single vertical line; they all peter out more or less in the median area between the two values 0,06 and 0,08 inches of the x-axis. Moreover, at least three curves A have their right ends at a level which is lower than that of the corresponding prior art curves, so that at least in the range from 0.06 to 0.08 inches the condenser core according to these curves A is not shown to be advantageous.

8. According to the description, the object of Figure 3 is to show the relationship between the heat transfer rate and the hydraulic diameters of the refrigerant flow paths. In the documents as originally filed there is no indication or suggestion that this figure is supposed to disclose any ranges or limits of the invention. The fact that the left part of Figure 3 is headed "Invention" does not necessarily imply that the full curves in this left part are to be considered as belonging to the invention or even completely disclose the invention, all the more as the right ends of certain curves A are well under the corresponding curves of the prior art as seen above, so that apparently they do not belong to the invention. The heading "invention" is here only used to distinguish the graphs concerning the invention from those of the prior art. Where the invention begins and finishes is not disclosed in Figure 3. How much the heat transfer rate has to be improved so that the present invention could be considered as showing advantageous effects over the prior art is also not specified. Moreover, in the absence of any information on the curves' ends, the person skilled in the art has no reason to think that these ends are of importance and he may think that in fact the curves are open-ended or were arbitrarily ended by the drawer. This seems to be confirmed by the fact that, considering only the right ends of the curves B, these ends - as said above - are not on a single vertical line, although they are still above the prior art curves. This is not the indication of a limit. Some right ends of the curves B are even substantially above the corresponding prior art curves and could have been prolongated on the right, while still showing advantages over the prior art. Since the object of Figure 3 was merely to show advantages of the invention, it has to be expected that the object of the graphs was to show the most interesting parts and not necessarily the whole invention; the description by stipulating the range of about 0.015. inches to about 0.040 inches in connection with Figure 3, see also the hydraulic diameter of 0.030 inches given in Table 1, contributes to support this assessment. When graphs, which are merely intended to show advantages of an invention, show that said invention could be performed beyond the ends of the drawn graphs, the person skilled in the art cannot assume on the sole basis of these graphs that said ends represent limits of the invention. Thus, it cannot be recognised that the curves A and B represent ranges of hydraulic diameters according to the invention and that the right ends of these curves must unmistakably represent the upper limits of the present invention.

Already for this reason, the impugned decision, to which Prof. Dr Dr Joseph Strauß in his legal opinion essentially referred, is to be set aside.

9. Supposing that, nevertheless, taking into account the fact that the curves B extend from about 0.04 inches to the median region between 0.06 and 0.08 inches and thus disclose that the invention can be performed above the upper limit of 0.04 inches expressely given in the original documents, the skilled person looks for the determination of an exact broader range, he receives from Figure 3 no clear indication as to how he can fix an upper limit value. According to the respondent, "all hydraulic diameters are disclosed as part of the invention, for which at least one of the eight curves shows an advantage in heat transfer over the prior art" and " the patentee may choose any value for the lower and upper limits of the claimed hydraulic diameter range for which at least one of the graphs shows advantageous heat transfer over the prior art"(submission dated 2 June 2003, page 18, first lines and lines 12 to 15). Regarding the opinions or statements filed by the respondent, it can be seen that the technical (Prof.Dr H. Müller-Steinhagen) and legal (Dr P. Dihm) experts differ on the determination of the upper limit of the curves A, which they respectively found to be 0.05 or 0.04 inches. Extrapolating the curves B, values about 0.08 inches could form part of the invention, so that it is not understood for which reason the invention, as far as condenser cores according to the curves B are concerned, shall only extend up to 0.07 inches. Moreover, considering the curves as disclosed, the respondent by claiming different values, namely 0.07, 0.068. and 0.065 inches, for said upper limit in the main and auxiliary requests, shows that arbitrary values can be chosen, so that there is in fact, in the patent application as filed, no clear and unambiguous disclosure of an upper limit for the hydraulic diameters.

10. It follows from the foregoing that the criterion "heat exchanger better than the prior art" used by the respondent for supporting the disclosure of an upper limit in Figure 3, is in fact not relevant. In the absence of any other disclosed criterion, it can only be deduced that, since the teaching of the present invention essentially concerns the use of small hydraulic diameters, an essential object of claim 1 is to define a range of said small diameters which is different from those already used prior to the filing date of the present application, that is to say said range should be under the lower limit of about 0.09 inches shown by the prior art curves of Figure 3. It is therefore a mere question of the choice of the upper limit of said range, as long as the present invention with said hydraulical diameter limit can show an advantage over the prior art. Being a mere question of choice, then a contradiction is to be seen between the now claimed value 0.07 inches and the originally disclosed upper limit of 0.04 inches, so that the upper limit not only is not clearly and unambiguously derivable from Figure 3, but it also does not comply with the conditions set out in T 169/83 (OJ 1985,193), to which the board adheres. Moreover, the new limit clearly makes a technical contribution to the subject- matter of claim 1, so that the criterion set out in the decision G 1/93 (OJ 1994, 541) also applies.

For all these reasons claim 1 according to the main request infringes Article 123(2) EPC.

11. Contrary to the opinion expressed by Prof. Dr Dr Joseph Strauß, the board in its previous decision T 669/93, which mainly dealt with the valid priority of a claim containing the originally disclosed range of 0.015 to 0.04 inch, did not take position on the claims of another request filed at this time and containing the range of 0.015 to 0.07 inch, since its decision was to send the case back to the first instance in order to examine the allowability of said claims. The mere fact that the board also drew the attention of the first instance to the possible need of a supplementary search is not to be considered as an implicit acceptance of these claims. The board had no reason at that time to examine in detail the claims or the actual disclosure of the patent in suit.

12. According to Article 112(1) EPC only questions concerning important points of law or concerning a uniform application of the law are to be referred to the Enlarged Board. The first set of questions to the Enlarged Board of Appeal does not concern such issues, since they all relate to the interpretation of a figure which comprises graphs. The interpretation of such a figure is of technical aspect, and not of legal aspect. Already for this reason, the corresponding request of the appellant is to be rejected.

Moreover, contrary to the respondent's view, the situations are not the same between the present case and the cases with which the decisions T 256/89 and T 145/87 had to deal. In case T 256/89 the newly introduced features were derivable from the preferred embodiment of the invention and from real experimental values which were identified by points on the curves. The end points of the curves in particular, which were used to define percentages, were clearly disclosed as being real experimental values. In T 145/87, the graph, which represented a mathematical equation, also comprised identified points, which were used to determine two constants of the formula. Thus, the circumstances are not comparable and it cannot be concluded that a discrepancy exists between the present decision and the two above cited decisions.

13. A reference to the U.S. application Serial No. 887,223 indeed appears in the description as originally filed of the patent in suit, however only as a disclosure for the method of making the tubes according to the present invention, and not as a disclosure of said invention; it is clearly specified in the patent application as filed that only the details of the means for forming the tubes are incorporated by reference, and nothing more. Thus, contrary to the respondent's allegation, this document cannot be used as support for the claimed upper limit value.

Moreover, said U.S. application, which was published on 25. August 1987, was not available at least at the date of publication of the parent patent application (No. 86307161.9/ EP-A-0 219 974, published on 29 April 1987), so that, being not made available to the public as required by Article 54(2) EPC, it cannot be taken into account. This is in line with the Guidelines, C-II, 4.18 and the case law of the boards of appeals, see T 737/90 (not published), as also acknowledged by Prof. Dr. Dr. Strauss in GRUR Inter. 1995, pages 103 to 112.

14. Under these circumstances, the second set of questions to the Enlarged Board is irrelevant for the present case and, further, already at least partly answered (questions a) to c)).

15. The reasons set out above for the main request would obviously apply to the claims 1 according to the auxiliary requests, so that these requests filed at a late stage of the proceedings are clearly not admissible (Article 114(2) EPC).