T 0476/94 06-10-1998

1. The appeal complies with the formal requirements of Articles 106 to 108 and Rules 1(1) and 64 EPC. It is therefore admissible.

2. Priority

According to Article 87(1) EPC it is a basic requirement for a valid claim to priority that the priority document and the European application (or later granted patent) be in respect of the same invention, in other words that the essential features of the invention claimed in the application or patent be disclosed as a matter of substance in the priority document, see for example T 81/87 (OJ EPO 1990, 250) and T 212/88 (OJ EPO 1992, 28).

The present patent is concerned with a heat transfer sheet for colour image formation. In the use of such a transfer sheet it is placed on an image receiving sheet and heat energy is applied to transfer the dyes from heat transfer sheet to the image receiving sheet. To form a colour image dyes of the three primary colours cyan, magenta and yellow are combined to give intermediates in a manner well-known in principle. The patent is particularly directed to providing a heat transfer sheet of this type which gives excellent colour reproducibility comparable with that obtained by conventional printing techniques.

In its broadest terms, as set out in claim 1 of the main request, the technical problem indicated above is solved by using cyan, magenta and yellow dyes which when transferred to an image receiving sheet satisfy particular conditions as to "hue error" and "turbidity". These two parameters are known measures for defining the colour characteristics of a dye or pigment and may be obtained following the evaluation method of the Graphic Arts Technical Foundation (GATF) explained on page 4 of the patent specification and in document D5. The appellants have consistently maintained that the definition of the permissible ranges for hue error and turbidity of the three dyes constitutes the core of their invention. But each of the earlier Japanese applications from which priority is claimed is wholly silent in this respect. Instead, each of them relates to a particular respective combination of cyan, magenta and yellow dyes for the dye carrier layers of a heat transfer sheet. Now, it is not in dispute that those combinations of dyes do in fact fall within the ranges specified in present claim with respect to hue error and turbidity, indeed the respective specific examples of the priority documents are substantially identical with Examples C1 to C3 of the patent specification, but that is not the point. What is decisive is that the priority documents contain no disclosure which is even remotely comparable with the way the invention is defined in the claim.

As a consequence the subject-matter of claim 1 is not entitled to the claimed priority date of 30 April 1986 and each of the documents D1 to D5 accordingly belongs to the state of the art according to Article 54(2) EPC. In these circumstances there is no need for the Board to go on to consider in detail the question of whether the priority documents were the first applications for the relevant subject-matter, the objection on the basis of which the Opposition Division denied the right to priority. For completeness the Board will however merely add that it in essence agrees with what the Opposition Division had to say on this point.

3. Novelty (main request)

Example E-1 of document D2 relates to a heat transfer sheet with respective cyan, magenta and yellow dye carrying layers in which the cyan dye is "Kayaset Blue 714", the magenta dye is a mixture of "MS Red G" and "Macrolex Red Violet" and the yellow dye is "Foron Brilliant Yellow S-6GL". Since these dyes, as well as the component proportions of the magenta dye, correspond to those used in Example C-1 of the patent specification, it is abundantly clear that the colour characteristics (hue error and turbidity) of the dye carrying layers fall within the respective ranges stated in claim 1. The appellants have never sought to contest this. Similar considerations apply between the Examples E2 and E3 of document D2 and Example C2 and C3 of the patent specification. (In comparing the cyan dyes of Example E2 and Example C2 it is to be noted that the relative proportions of "Kayaset Blue 714" and "Forum Brilliant Blue S-R" are reversed but since both of these components per se meet the hue error and turbidity requirements so must any mixture thereof, irrespective of the relative proportions. With respect to the comparison between Example E3 and Example C3 it is to be noted that the magenta dye "Sudan Red 7B" of Example E3 differs only in name from the magnetic dye "Ceres Red 7B" of Example C3.)

It is a basic principle of patent law that a specific disclosure will take away the novelty of a broad claim embracing that disclosure, see for example T 188/83 (OJ EPO 1984, 555) and T 508/91 (mentioned in the publication "Case Law of the Boards of Appeal of the EPO", page 53, point 2.5). The Board can find no support in the case law for the contention of the appellants that for a claim which defines a parameter in terms of a range of permissible values to be anticipated it is necessary that both the parameter as such as well as the range of values which it can take be explicitly addressed in the state of the art. The appellants, by means of their present claim 1, seek protection for a heat transfer sheet comprising dye carrying layers with specific colour characteristics. The dye carrying layers of the heat transfer sheets of Examples E1 to E3 of document D2 incontrovertibly exhibit those characteristics. The subject-matter of claim 1 therefore lacks novelty (Article 54(2) EPC).

In the circumstances of the present case the Board, in contrast to the appellants, can see no logical contradiction whatsoever between the finding, with respect to what is essentially the same technical disclosure, that there is no entitlement to priority on the one hand, and novelty-destroying anticipation on the other. It is true that in the "Guidelines for Examination in the EPO" the test for entitlement to priority is compared, via the test for addition of subject-matter contrary to Article 123(2) EPC, to the test for novelty (Section C-V, 2.4 in combination with C-VI, 5.4). What is meant by this, as indeed stated specifically in Section C-V, 2.4, is that for the priority date to be allowed the subject-matter of a claim under consideration must be derivable directly and unambiguously from the disclosure of the invention in the priority document. It is a long way from this to what the appellants seem to be contending, namely that there is an entitlement to priority if the disclosure in the priority document would constitute a novelty-destroying anticipation of the subject-matter of the claim. That may indeed be a reasonable premise in straight-forward cases but is clearly inapplicable in situations where, as in the present case, the claim contains generalisations going beyond what is disclosed in the priority document. The difficulty of applying a "novelty test" to corresponding types of amendment of an application has long been recognised, see T 194/84 (OJ EPO 1990, 59) where a modified form of the test for such situations is proposed. Subsequent decisions, see in particular T 288/92 (mentioned in "Case Law of the Boards of Appeal of the EPO" at page 166) have in any case called the fundamental appropriateness of the "novelty test" to the issue of added subject-matter into question. Be that as it may, the present Board is convinced that if the "novelty test" were applied to the present set of circumstances then the result, namely that the subject-matter of claim 1 is not entitled to the claimed priority date, would be the same.

It must also be noted that document D2, since it has an earlier European filing date than the priority date claimed by the present patent, would in any case belong to the state of the art according to Article 54(3) EPC even if that priority date were recognised and accordingly would have to be taken into account for assessing novelty. The debate on the logical contradiction which the appellants seek to identify is therefore to all intents and purposes a diversion. Certainly, it is very difficult in the circumstances of the present case to see how the appellants should arrive in a better position vis-à-vis document D2 by not being entitled to the claimed priority.

Document D1 discloses in Examples 1, 6 and 7 single colour heat transfer sheets provided with a cyan, a yellow and a magenta dye carrying layer respectively. The cyan dye is "Kayaset Blue 714", the magenta dye "MS Red G" and the yellow dye "PTY-52". Each of these dyes is referred to in the present patent specification as being a preferred embodiment of a dye having colour characteristics as required by claim 1 (see for instance the Examples C1 to C3 of the patent specification discussed above). Now, although claim 1 is directed to "a" heat transfer sheet, it is when read in the light of the totality of the disclosure clearly not intended to be restricted to an arrangement where respective cyan, magenta and yellow dye carrying layers are provided on a single substrate. This is shown for example by the statement at lines 45 to 46 of page 3 that the "respective dye carrying layers may be formed separately on a plural number of sheets"; by the fact that Example B-1 relates to such separate single colour sheets; and the introduction first into dependent claims of the requirement that "the substrate sheet comprises one sheet". Taking into account the broad ambit which claim 1 is evidently intended to have its subject matter therefore also lacks novelty with respect to the disclosure of document D1.

Document D3 is specifically concerned with the same technical problem as that addressed by the contested patent, namely the provision of a heat transfer sheet giving excelling colour reproducibility and more particularly, the choice of cyan, magenta and yellow dyes for the respective dye carrying layers in order to achieve this end. According to the teachings of document D3 each of the dyes should have a reflection density of 1.3 after transfer onto an image receiving sheet and a wavelength dependent spectral reflectance lying within upper and lower limits determined by a pair of complex formulae for each colour. Figures 1 to 3. show the permitted reflectance/wavelength ranges plotted graphically for yellow, magenta and cyan respectively. On page 8 there is given a list of examples of dyes which may be used, followed by their chemical formulae. Two specific examples of heat transfer sheet are then discussed. In Example 2 the heat transfer sheet comprises a single substrate sheet with respective dye carrying layers containing "GY-9" as the yellow dye, "NK-1584" as the magenta dye and "Kayaset B-776" as the cyan dye. The chemical formulae for "Kayaset B-776" corresponds to formula No. 24 of one of the particularly preferred dyes referred to in the patent specification. According to the notice of opposition the respondents prepared the dyes "GY-9" and "NK-15845" according to their chemical formulae and determined for the yellow dye "GY-9" a hue error of 2% on the red side and turbidity of 6%, and for the magenta dye "NK-1584" a hue error of 13% on the red side and a turbidity of 8%. These findings have not been challenged by the appellants and it is not in dispute that Example 2 of document D3 is a heat transfer sheet meeting all the requirements of present claim 1.

Recognising this, the appellants have sought to establish the novelty of the subject-matter of claim 1 by including a disclaimer to Example 2 of document D3. In their view, that example was a mere incidental disclosure which has nothing to do with the basic core of their invention and a disclaimer was a recognised and appropriate tool for avoiding such "accidental anticipation". The Board cannot agree. The colour characteristics of hue error and turbidity used in the definition of the subject-matter of claim 1 are closely related to the reflectance/wavelength relationships according to which the dyes of document D3 are to be selected. As a consequence there can be no doubt that a large proportion, if not the substantial majority, of dyes meeting the requirements of document D3, and not just those of Example 2, will also meet the requirements of present claim. Thus the disclaiming of that single example cannot eliminate the broad overlap with the teaching of this state of the art and does not render the subject-matter of the claim novel, see T 183/88 (supra) and T 290/86 (OJ EPO 1992, 414).

From the above it can be seen that the respondents succeed with their attack of lack of novelty with respect to each of the documents D1, D2 and D3. They also alleged lack of novelty with respect to document D4, relying on the translation of the claims into English they have filed and for the rest on the chemical formulae for dyes to be found in the untranslated description of the document. From these chemical formulae it is apparent that some of the dyes proposed in document D4 correspond to preferred examples of dyes set out in the present patent. On the basis of the information available it cannot however be satisfactorily determined whether document D4 unambiguously teaches a heat transfer sheet as presently claimed comprising respective cyan, magenta and yellow dye carrying layers, each of which has the respective colour characteristics set out in present claim 1. A finding of lack of novelty with respect to document D4 is not therefore possible.

4. Auxiliary request

In comparison with claim 1 of the main request it has been specified in claim 1 according to the auxiliary request that the heat transfer sheet consists of the respective dye carrying layers and one substrate sheet. The purpose of these restrictions is to make it clear that the heat transfer sheet is provided with each of the respective dye carrying layers, i.e. is not a single colour sheet, and that the heat transfer sheet consists solely of the dye carrying layers and the substrate sheet, i.e. no other layers are involved. With respect to the latter requirement the respondents pointed to the fact that the preferred embodiments of the heat transfer sheet described in the patent specification comprise one or both of an addition heat resistant layer and a tack retentive layer. It is however clear from page 22, lines 29 to 3 and lines 40 and 41 of the patent specification that these additional layers can be dispensed with, so that a basis for the amended claim is present.

It can be left undecided whether the amendments made to claim 1 are sufficient to avoid anticipation by the state of the art according to documents D1 and D2 since with regard to document D3 this is certainly not the case. There, respective cyan, magenta and yellow dye carrying layers are coated onto a single polyethylene terephthalate sheet to form a heat transfer sheet, with no other layers being present, see Examples 1 and 2.

The subject-matter of claim 1 according to the auxiliary request therefore lacks novelty.