T 0711/90 15-09-1993

I. European patent No. 0 018 110 based on application No. 80 30 953.9 was granted on the basis of 12 claims.

II. The Respondent (Opponent) filed a notice of opposition requesting revocation of the patent on the ground of lack of inventive step.

III. In response to the notice of opposition, the Appellant (Patentee) filed an amended set of claims with the letter dated 7 November 1986. In a first communication of 15 April 1988, the Opposition Division indicated the reasons for which the amended Claim 1 did not meet the requirements of Articles 123(2) and 84 EPC (clarity). In reply thereto, the Appellant submitted a second set of claims with the letter of 25 July 1988. The parties were informed by a second communication dated 16 August 1989, that Claims 1 and 6 of this set of claims did not comply with the requirements of Article 123. The Appellant was given the opportunity to comment on the reasons given in this communication but did not present any observations.

IV. The Opposition Division revoked the patent. According to the decision of revocation, the two sets of claims filed with the Patentee's letters of 17 November 1986 and 25 July 1988 respectively did not comply with Article 123(2) and in, one instance, with Article 123(3) for the reasons given in the communications referred to above. Moreover, the subject-matter of Claims 1 and 6 of the patent as granted was considered not to involve an inventive step.

V. The Appellant lodged an appeal against this decision and submitted a third amended set of Claims on 13 November 1990 together with the Statement of Grounds of Appeal. In a communication pursuant to Article 110(2) EPC, the parties were informed that the wording of Claim 1 filed on 13 November 1990 was ambiguous and that Claim 10 appeared not to be in conformity with the requirements of Article 123(2). It was further pointed out that a soda amount of 15 to 25% did not seem to be compatible with the amounts of B2O3, BaO and SiO2 recited in Claim 10. Both parties were invited to comment on the ground of insufficiency of disclosure raised by the Respondent. In response to this communication, the Appellant filed a fourth amended set of Claims on 25 March 1993.

VI. Oral proceedings were held on 15 September 1993 in the absence of the Respondent. In a telefax dated 6 September 1993 the Respondent informed the Board that it would not attend the oral proceedings.

At the beginning of the oral proceedings the Appellant was told the reasons for which it was doubtful that the fourth set of claims meets the requirements of Article 123(2) and 84. After consideration of these reasons the Appellant submitted an amended Claim 1 as main and single request. This claim reads as follows:

"A high numerical aperture optical fibre core glass having a composition chosen so that it is not subject to devitrification or phase separation and having a refractive index greater than 1.54, said glass containing 0.01 to 1% by weight of arsenic trioxide as a redox buffering agent to maintain a fictive partial oxygen pressure of substantial 1 Pascal in the glass, wherein the glass consists of:

(i) 15-25 mole % of soda

(ii) 5-20 mole % of boric oxide or 5-20 mole% of a mixture of boric oxide and barium oxide such that up to 12 mole % of the glass is barium oxide, and

(iii) 25-65 mole % of silica or 25-65 mole % of a mixture of germania and silica such that up to 42 mole % of the glass is germania,

the glass including at least 5 mole % of boric oxide plus either at least 8 mole % of barium oxide or at least 8 mole % of germania"

VII. During the oral proceedings The Appellant's attention was drawn to the fact that this claim was unclear. Although the use of the terms "the glass consists of" excluded the presence of components other than those denoted (i), (ii) and (iii), the proportions of these components could not add up to 100 mole % in particular when the content of component (iii) was its lower limit of 25 mole % since the maximum proportions of the remaining components (i) and (ii) were 25 mole % and 20 mole % respectively. Even if arsenic trioxide were taken into consideration, a total of 100 mole % could not be reached. The Appellant was told that the terms "the glass consists of" were not in agreement with the feature stated in the fifth line of the claim that the glass additionally contains 0.01 to 1% by weight of arsenic oxide. The question of the conformity of this claim with the requirements of Article 123 was also discussed in particular in connection with the lower limit of 5 mole % for the mixture of boric oxide and barium oxide and with the limitation to a glass including at least 5 mole % of B2O3 plus at least 8 mole % of either BaO or GeO2.

As regards clarity, the Appellant argued that the first deficiency (i.e. total amount of the components lower than 100 mole %) resulted from two mistakes in the limits given for the proportions of components (ii) and (iii). The correct lower limits should be 10 mole % for the amount of component (ii) and 55 mole % for the content of component (iii), instead of 5 and 25 mole %. The Appellant handed over a ternary diagram similar to that submitted during the examining procedure (cf. letter dated 4 January 1982) in order to show that the amended limit were derivable from the ranges indicated in the original application, assuming the glass to contain only components (i), (ii) and (iii).

Concerning the allowability of the amendments under Article 123, the Appellant contended that the alternative lower limits of 8 mole % for BaO and GeO2, together with the 5 mole % lower limit for B2O3 were all clearly based on the examples of table IV (cf. table IV of the patent in suit, 6th, 9th and 11th examples and table IV of the original application). It was further argued that the glass compositions of table IV contained only the components denoted (i), (ii) and (iii) in the claim. Therefore the terms "consist of" were directly derivable from the original application.

VIII. The Appellant requested that the decision under appeal be set aside and that the patent be maintained on the basis of the Claim 1 submitted during the oral proceedings. The Respondent had requested in writing that the appeal be dismissed.