T 0265/05 (Operating a synchronous memory/RAMBUS) 18-01-2008

1. Added subject-matter

1.1 The oppositions were filed in particular on the ground that the patent as granted contained subject-matter which extended beyond the content of the parent application as filed (Articles 100(c) and 76(1) EPC 1973). In order to overcome these objections the appellant has amended the independent claim. The Board must therefore first consider the question whether a patent granted on a divisional application may be amended for this purpose.

1.2 The Enlarged Board of Appeal decided in the case G 1/05 - Divisional/ASTROPOWER (to be published in OJ EPO) that a divisional application which at its actual date of filing contains subject-matter extending beyond the content of the parent application as filed can be amended later in order that its subject-matter no longer so extends (cf the order). In arriving at this finding, the Enlarged Board of Appeal in particular relied on a direct correspondence between Article 76(1) and Article 123(2) EPC 1973, both Articles enshrining the same principles (points 5.1 to 5.4).

Pursuant to Article 123(2) EPC a European patent application or a European patent may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed. The present Board observes that, since Article 123(2) EPC applies to both patent applications and patents, there seems to be no reason why the finding in G 1/05 should not apply also to opposed patents. This view is in line with the decision in case T 687/05 (not published in OJ EPO), where the deciding board, noting that anything disclosed in a patent granted on the basis of a divisional application must be derivable from the parent (and any grandparent) application as filed (point 3.1), allowed amendments of a patent in order to overcome this kind of objection (point 1).

In fact, at the oral proceedings before the Board the respondents did no longer deny that it was admissible to amend the patent-in-suit with a view to eliminating subject-matter added with respect to the parent application. They were however of the opinion that the amendments proposed by the appellant were insufficient, as set out in the following paragraphs.

1.3 First, the respondents have argued that the present claim did not exclude the possibility that all or some write request packets were treated differently from the read request packets. According to the description not only the read request packets but also the write request packets included a block-size value that defined the amount of data to be transferred and to which the semiconductor memory responded. If this were not the case the aim of avoiding collisions on the bus could not be achieved. The claim was however silent on how information was written into the semiconductor memory device.

The appellant's view was instead that the claim's restriction to reading operations was a mere limitation compared with the described embodiment. It was possible to claim only the reading operations since these were separate from the writing operations.

The Board agrees with the respondents that if the possibility that write request packets are differently processed than read request packets were now claimed, subject-matter would indeed have been added. In the Board's view, however, the claim does not fairly allow such a reading. It mentions "bus transactions which transfer information between said semiconductor devices (11,13) on said bus (18)". "Transactions", as this word is consistently used in the patent, includes both reading and writing operations. By the same token, "request packet" covers both write request packets and read request packets. It is therefore clear from the claim that the system on which the method is performed must use write request packets containing a block-size value. Furthermore, reading operations are independent of writing operations in the sense that all requests on the bus are separated in time, as the appellant has pointed out. The claimed subject-matter is thus derivable from the parent application.

Moreover, even if it is true that the claim does not expressly exclude the possibility that all or some writing operations are performed in a different way than the reading operations, nor does it expressly exclude the existence of some reading operations that are performed differently. In fact, any claim can always be thought of as encompassing an infinite number of undisclosed embodiments. Determining what features must be included in a claim in order to restrict its ambit to what has actually been invented is thus a question of degree, and in the present case the Board judges that the claim contains sufficient limitations with regard to the block-size value.

1.4 Secondly, the respondents have argued that the feature concerning the "external clock signal having a fixed frequency", present in claim 1 as granted, cannot appear in the amended claim in this short form. Original dependent claim 38 (including original claims 25, 26 and 28), which forms the basis for the present claim, contains no clock feature at all whereas the description refers to a very particular clocking circuit (see fig.8 and associated text of the parent application). The present claim would therefore constitute an inadmissible intermediate generalisation.

The Board cannot agree with this argumentation either. It is true that the parent application described a specific clocking method as a suitable possibility for high-frequency operation of the bus (see eg p.46, l.20 to 23 of the parent application). A bus subsystem comprising such a clock generator was claimed in original independent claim 73. Original claim 38, however, did not mention any clock signal, thus allowing the use of conventional clocking schemes. This is supported by the fact that in accordance with the original disclosure the described clock circuit is provided to permit high speed clock signals to be sent along the bus with minimal clock skew between devices (see p.6, l.13 to 15 of the parent application), ie relates to improving the operation of the bus subsystem in a particular situation. The claim however is not limited to any particular speed. The specific features of the described clock generator hence need not be included in the claim.

1.5 It follows that the amendments made to claim 1 do not contravene Article 76(1) EPC 1973. Nor do they contravene Article 123(2) EPC since the divisional application as filed contained all the subject-matter of the parent application.

2. Clarity

2.1 The respondents raised a number of clarity objections against the present claim. In particular, it was regarded as obscure that the block-size value at one instance in the claim "encodes and specifies" the size of a block and at another instance "defines" an amount of data. This seems however to be a mere stylistic variation that cannot conceivably lead to misunderstandings. Furthermore, it was objected that the feature "means for said master device to request said semiconductor memory device (13) to prepare for a bus transaction by sending a request packet" should also be included in the form of a method step. The Board is however of the opinion that in a claim for a method of operation of a memory device (and not of a master device) it is sufficient to state that means having the indicated function are present.

2.2 Thus, the Board holds that the claim is sufficiently clear in the sense of Article 84 EPC 1973.

3. Remittal, novelty and inventive step

3.1 At the oral proceedings before the Board all respondents withdrew their objections under Article 100(a) EPC 1973 and urged the Board to decide the case without remittal to the first instance for further prosecution.

3.2 When exercising its discretion under Article 111(1) EPC 1973 either to decide or to remit the case, the Board should take account of its particular circumstances and the parties' wishes. The parent application was filed already in 1991, the patent for the present divisional was then granted in 2001. The opposition proceedings were terminated after four years by a two days' hearing before the opposition division. The present state in appeal proceedings was reached after a three days' hearing before the Board, in both proceedings the focus was on added subject-matter only. Hence, the case until now required a great deal of effort from the parties, so that their common wish for an immediate final decision is understandable.

Moreover, as mentioned above the respondents did not raise any objections with respect to novelty or inventive step against the newly amended claim so that they apparently accepted, or no longer felt affected by, the claimed subject-matter in substantive respect. Thus, either the Board, or - after a possible remittal - the opposition division would have to carry out any further examination of its own motion without participation of the respondents. Under these circumstances, the only compelling reason the Board can see for not allowing the request immediately itself would be a situation of prima facie lack of patentability based on available information, or a situation of fundamental uncertainty because of lack of information, in particular if further preparatory work by the first instance appeared necessary to safeguard the interests of the public.

3.3 This is however not the case. The subject-matter of claim 1 has been limited considerably. The claimed feature combination was not present in any of the granted claims but has been taken from an original claim and the description. It now defines in some detail the system on which the claimed method is performed, including several bus features, a modifiable address register, request packets and control information including information about an access time. Although at least some of these features were known as such at the date of priority, as acknowledged in the description, novelty is not an issue and it cannot be concluded that the combination of features was straight forward having regard to the prior art considered by the opposition division in its "Comments". It is therefore not to be expected that a remittal would lead to any amendment to the patent in its present form, let alone to its revocation. For this reason, and taking particular account of the fact that all parties wish the proceedings to be concluded without further delay, the Board chooses to exercise its discretion under Article 111(1) EPC 1973 to decide the case itself.

3.4 Since there are no further objections against the patent, the Board decides to maintain it as amended in the oral proceedings.