T 0667/01 (Optical recording medium/SANYO) 15-02-2006

Reasons for the Decision

Main request

1. Admissibility of amendments (Art. 123(2) and (3) EPC) and support (Art. 84 EPC)

Claims 1 to 4 were filed during the oral proceedings. The question of their admissibility accordingly arises since they were filed at a late stage of the procedure and in the absence of the respondent.

1.1 With regard to the time of filing, the board notes that the amendments were made in an attempt to overcome the objections raised in the communications of 2 March and 18 November 2005 and discussed during the oral proceedings. They take form of an additional disclaimer. In the board's view these amendments are straightforward and merely serve to remedy the objections previously raised without raising new issues which would delay the procedure. The board was in consequence in a position to maintain the patent in amended form as discussed below.

1.2 According to Article 113(1) EPC, the decisions of the European Patent Office may only be based on grounds or evidence on which the parties concerned have had an opportunity to present their comments. In the present case, the question arises as to whether the opponent would have been entitled to claim that he was taken by surprise as a result of the board admitting the amendments filed in his absence during the oral proceedings. The board considers that this is not the case and that admitting the claims as amended during oral proceedings in the absence of the opponent does not conflict with the requirements of Article 113(1) EPC or indeed with opinion G 4/92 (OJ EPC 1994, 149) of the Enlarged Board of Appeal. According to this opinion, a party who fails to appear at oral proceedings must have the opportunity, in accordance with Article 113(1) EPC, to comment on new (and therefore surprising) facts and evidence submitted in these proceedings. In the present case, the objections to the claims were not new, having been raised in the communications of 2 March and 18 November 2005. In such a situation, the opponent could not have been taken by surprise by amended claims, because he could reasonably expect the appellant to try to overcome these objections.

Therefore, the board admitted the claims filed during oral proceedings into the procedure.

1.3 In the course of the opposition proceedings, three equations were introduced into claims 1 and 3; these correspond to equations 14, 7 and 8 of the originally filed application. The feature "where m is set to the smallest possible value", also introduced during the opposition proceedings, is found on page 18, lines 5 to 7 of the originally filed application. The original disclosure of the equations and of this feature was not put into question by the respondent.

1.4 The respondent did however raise objection under Article 123(2) EPC to the introduction into claims 1 and 3 of the feature "delta1, delta2, (m+1)pi are in radian". This feature was not explicitly disclosed in the original application. In the board's view it is, however, simply a clarification. In the equation

FORMULA/TABLE/GRAPHIC

the angles delta1, delta2, (m+1)pi must be understood as being in radians since any angle based on pi is by definition in radians.

1.5 Finally, the disclaimer in claims 1 and 3 was introduced in order to restore novelty by delimiting these claims against state of the art under Article 54(3) and (4) EPC. In the light of the decision G 1/03 (OJ EPO 2004, 413) of the Enlarged Board of Appeal, the introduction of disclaimers is allowable under such circumstances (see Order 2.1). The board is also satisfied that the disclaimer corresponds to the requirements of conciseness and clarity explicitly addressed in the decision of the Enlarged Board (point 3, 3rd paragraph) as it disclaims 3 pairs of parameters in addition to properties common to these parameters in a way immediately comprehensible to the skilled person.

1.6 As the above amendments derive from the application as originally filed and do not extend the protection conferred by the European patent, they comply with the requirements of Art. 123(2) and (3) EPC.

1.7 The respondent's argument in his letter of 23 November 2001 that the smallest possible value of m was virtually always m = 0 and that none of the disclosed media satisfied this requirement is understood as an objection under Art. 84 EPC.

The board agrees that an apparent lack of clarity arises from the use of the term "smallest possible value". This term is, however, to be interpreted in the context of lines 21-49 on page 6 of the patent from which it appears that there is a trade-off between the value of m, and hence the recording layer thickness, and the required laser power. It would be clear to the skilled person that the lower limit to the value of m is given by the thinnest technically feasible recording layer. Thus, the formulation "smallest possible value" is to be understood in this context.

2. Public availability of the content of D9, Art. 54(2) EPC

2.1 D9 is apparently based on a lecture given at a meeting sponsored by the International Society for Optical Engineering (SPIE) and which took place on 17 January 1989, i.e. before the claimed priority date of the patent in suit. It is common ground that the meeting was open to the public. D9 does not have a specific publication date.

In the absence of any evidence to the contrary, the board considers that the declaration by the SPIE director of publications given in E1 together with the accompanying printout E2 relating to the publication date of D9 sufficiently prove that D9 was actually published on 19 May 1989 and thus after the claimed priority date of the patent in suit. D9 is therefore not part of the state of the art under Art. 54(2) EPC. The respondent has not contested this finding.

2.2 It is, therefore, necessary to investigate the extent to which the oral presentation before the claimed priority date was based on the content of D9.

2.3 It follows from the established case law of the Boards of Appeal that a written publication allegedly based on a paper previously read at a public meeting held some time earlier cannot be assumed to be identical to what was orally disclosed. Reference is made to decision T 1212/97, unpublished, points 1-13 of the reasons, which states that the content of a prior publication which is material for the maintenance or revocation of a patent must be proved beyond any reasonable doubt. With respect to oral presentations during a conference, a declaration of the presenter as to the content of his presentation is not usually regarded as sufficient since the presenter may have deviated during his presentation from what he intended to present and from what he later remembers as having presented, or he may have presented relevant issues in such a way that the audience was unable to take note of it. If the extent to which the audience understood the presented issues remains uncertain, the established standard of proof typically requires a further, independent statement by a person having attended the presentation. In the present case, the statement E4 by one of the presenters, Dr. Hamada, relating to the content of the presentation was made 12 years after the presentation. There must remain considerable doubt as to whether the presenter can, after such a long period, still remember what exactly was presented. The statement E4 was accompanied by a number of copies of slides E5 titled "That's CD-R" by the same authors as D9. No statement of a member of the audience and no independent proof was given as to whether any or all of the slides were presented during the conference.

2.4 In the absence of independent proof as to whether the content of D9 was actually made available to the public before the claimed priority date, the board considers there is insufficient evidence that this was the case, according to the usual standard of proof. The disclosure of D9 is therefore not considered to be prior published and therefore not relevant to novelty and inventive step.

The board has arrived at this conclusion without taking into account document E3, submitted by the appellant in order to prove that the oral presentation given on 17 January 1989 was different from the content of D9.

3. Novelty with respect to the disclosure of D6, Art. 54(3) EPC, main request

3.1 Claim 1 of the main request relates to an optical recording medium having a three layer structure with a transparent substrate 1, a light-transmitting recording layer 2 and a reflecting layer 3 arranged in that order, the recording layer being adapted to be of variable thickness locally in response to a light beam in order to record data. It appears to be common ground that such three layer structures were known at the claimed priority date.

The reflectance of the recording layer is determined according to physical laws by various parameters including its thickness. Again according to physical laws, the reflectance shows maxima and minima as a function of the thickness of the recording layer and determined by various parameters as given by the equations in claim 1.

As the physical laws given by the equations in claim 1 merely describe the reflectance properties of the above three layer system, the invention is understood to reside in the following features:

(i) the thickness of the recording layer in the unrecorded state is set to a predetermined value where the reflectance is maximum,

(ii) the wavelength lambda of a laser beam is set to 0.78 µm,

(iii) the integer m, which is a free parameter determining possible maxima, is set to the smallest possible value,

(iv) the extinction coefficient k2 of the reflecting layer at wavelength lambda is set higher than the corresponding value k1 of the recording layer,

(v) the refractive index n2 of the reflecting layer at wavelength lambda is set smaller than the corresponding value n1 of the recording layer.

Three specific sets of parameters corresponding to three specific disclosed in D6, are excluded.

3.2 In comparison with D6, the following is found:

Features (iv) and (v) result from the fact that the reflecting layer is a metal. All prior art is assumed to meet this condition; with respect to D6 reference is made to page 13, lines 44 and 45 and table 1.

Feature (ii) appears to be standard in the art and is disclosed in D6, see p. 14, l. 4.

Features (i) and (iii) do not follow explicitly from D6. They can, however, be determined by the parameters given in table 1, sample 2 on page 14 of D6 with the help of the equations of claim 1. The calculation was presented by the respondent during the oral proceedings before the opposition division and corresponds to annex page 2/7 of the minutes of those oral proceedings. It results in a value d2 of 140.9 nm for a minimum value m of 1. The actual value of d2 according to table 2, example 2 on page 15 of D6 is 140 nm.

A similar calculation (see respondent's letter of 23 November 2001) can be performed for the parameters given in table 1, sample 1 on page 14 of D6 resulting in a value d2 of about 135 nm for a minimum value m of 1. The actual value of d2 according to table 2, example 1 on page 15 of D6 is 140 nm.

Since D6 is prior art under Art. 54(3) EPC it is only relevant to the novelty of the subject-matter of claim 1. However, it follows from page 1/7 of the above annex to the minutes that the thickness of the recording layer in the example given in the patent in suit on page 6 (the reference to page 5 in said annex is apparently a mistake), lines 12-17 deviates in a similar manner from the thickness value as calculated from claim 1. Furthermore, claim 1 as granted comprises the wording "is a maximum or close to maxima". From this, the board concludes that claim 1 of the main request has to be interpreted such that it actually comprises thickness values close to the values given in the claim. From the above comparison between the example on page 6 of the patent and the value derived from claim 1, it follows that "close to" must embrace a deviation of about 10%.

Therefore, upon a proper interpretation D6 discloses all of the above features i - v.

3.3 The subject-matter of claim 1 is, however, rendered novel with respect to the teaching of D6 by the introduction of a disclaimer directed to the specific features of examples 1, 2 and 3 of D6.

3.4 The respondent argued in his letter of 23 November 2001 that the disclaimer in claim 1 only excluded examples of D6 and did not take away the novelty-destroying teaching of D6 as a whole. The mathematical description in claim 1 had already been disclosed in D6.

The board notes that the respondent's arguments have already been considered under point 3.2 above. The respondent was not able to show that D6 disclosed an optical recording medium "not including the condition of the substrate made by polycarbonate, reflecting layer made by gold and the recording layer" having optical characteristics other than those given by the examples.

3.5 As a result, D6 is not relevant for considering the patentability of the subject-matter of the claims according to the main request.

3.6 Similar arguments apply, mutatis mutandis, to independent claim 3.

4. Thus none of the objections raised by the respondent against the subject-matter of the claims of the main request are convincing. Therefore, the appellant's main request is found allowable and, consequently, it has not proved necessary to consider the auxiliary requests.