T 1400/16 27-10-2017

1. The appeal is admissible.

2. Main request

2.1 Clarity (Article 84 EPC)

2.1.1 The invention concerns a dental panoramic x-ray imaging system having an x-ray source and an imaging device which move around the patient's head according to a predetermined geometric path and speed profile (paragraph [0010] of the patent; Figure 3). The movement is such that an image of a predetermined layer of interest is formed. The invention allows the x-ray scan to be performed by moving the x-ray source and imaging device in a continuous movement around the patient's head (paragraph [0030]).

The movement is defined in claim 1 (feature (c)) by specifying a "rotational axis around which the x-ray source and imaging device move along a predetermined geometric path, the axis being located between the x-ray source focal point and the x-ray imaging device and the predetermined geometric path being a spline, which is a non-circular trajectory".

2.1.2 The appellant objected that the definition of the motion along a path being "a spline, which is a non-circular trajectory" lacked clarity. However, since claim 1 of the granted patent already defined the motion along a path being "a spline", the notion of a "spline" by itself cannot be objected to as lacking clarity. Only the qualification of a spline as one "which is a non-circular trajectory", which was added during opposition proceedings, may be challenged as lacking clarity. Hence, the appellant's contention that the claim lacked clarity because it did not specify whether the entire trajectory, or merely a portion of it, should be a spline is not to be examined as it refers exclusively to the feature of a spline trajectory, not to the added qualification that it should be a non-circular one.

2.1.3 It is common general knowledge that a "spline" is a continuous curve having continuous derivatives. This concept corresponds, for example, to the definition in the Shorter Oxford English Dictionary (E1) and the Wikipedia article "Spline (mathematics)" filed with the statement of grounds of appeal. In essence, "spline" designates a smooth curve, without sharp turns or kinks (as in a "V"-shaped curve).

Hence, a "spline" has an established recognised mathematical meaning in the field. The appellant has nevertheless argued that the claimed expression "a spline, which is a non-circular trajectory" could be interpreted as providing a "legal definition" of the term spline such that a spline is a trajectory which is non-circular.

The Board views this interpretation, however, as a contrived interpretation of the term "spline", at odds with its established recognised mathematical meaning in the field. The skilled person would consequently not read the claimed expression in such a way. As explained in the patent as granted (page 8, lines 26 to 28), the movement along a spline can be either a circular or a non-circular trajectory, and in the presently pursued claim 1 the movement of the x-ray source and imaging device is limited to a non-circular trajectory. Hence, the claimed expression of "a spline, which is a non-circular trajectory" can be given no meaningful reading other than that of a non-circular spline trajectory.

2.1.4 The Board therefore concludes that the qualification of a spline as one "which is a non-circular trajectory", added during opposition proceedings, does not infringe the clarity requirements of Article 84 EPC.

2.2 Priority right

2.2.1 It is undisputed by the parties that application US 11/277,530, from which the patent claims its priority, is represented by document D4. It is likewise undisputed that if the claim to priority fails, D4 is comprised in the state of the art within the meaning of Article 54(2) EPC (as it was published on 14 September 2006, before the 10 November 2006 filing date of the parent of the divisional application leading to the patent in suit) and that, in that case, D4 is novelty-destroying.

2.2.2 What was disputed, however, is whether priority could be validly claimed from D4 since the same applicant had already disclosed the same invention in the earlier previous application US 60/677,020 (USPRE). USPRE had been filed on 2 May 2005, i.e. before the 27 March 2006 filing date of D4 and about 18 months before the 10 November 2006 filing date of the parent of the divisional application leading to the patent in suit.

2.2.3 According to Article 87(1) EPC, only the first application filed in a state party to the Paris Convention or a member of the WTO can form the basis for a priority right. Therefore, if apart from the application whose priority is being claimed in the patent (in this case D4), an earlier previous application had also been filed (in this case USPRE), in order to check the validity of the priority claim it must be established whether the invention claimed in the patent was already disclosed in the earlier previous application (USPRE).

To establish whether the invention claimed in the patent was already disclosed in the earlier previous application, USPRE, the same principles have to be applied as when establishing identity of invention between the application forming the basis for priority and the application claiming priority. The question is whether the person skilled in the art could derive the subject-matter of the claim of the patent directly and unambiguously, using common general knowledge, from the earlier previous application USPRE (G 2/98, OJ 2001, 413). As confirmed in G 1/03, point 4 of the Reasons, the disclosure as the basis for the right to priority under Article 87(1) EPC and as the basis for amendments to an application under Article 123(2) EPC has to be interpreted in the same way.

2.2.4 The respondent disputed that USPRE directly and unambiguously disclosed that the trajectory of the x-ray source and imaging device was a non-circular spline trajectory.

2.2.5 In the Board's view such a trajectory is disclosed in USPRE for the following reasons:

USPRE discloses in claim 1 that the x-ray source and imaging device rotate on a circular or non-circular trajectory. USPRE does not explicitly mention that the trajectory is a spline, i.e. essentially a smooth curve without sharp turns or kinks, as explained under point 2.1.3 above.

However, the Board considers that from what is disclosed on page 16, paragraphs 4 and 5 in connection with Figure 7, such a trajectory inevitably occurs in USPRE as well. This passage explains that a transversal layer is obtained, the layer being transversal to the panoramic images which follow the contour of the jaw and parallel to the direction of radiation. Thus, the direction of radiation will be perpendicular to the panoramic images or layers which are illustrated in Figure 7. This is what Figure 3 illustrates too, albeit with reference to prior-art orthopantomographs (OPG), in which the perpendicularity of the center of the x-ray beam to the panoramic layer is expressly indicated by a graphical symbol denoting perpendicularity. Moreover, in the description of Figure 3, on page 3, paragraphs 4 and 5, it is mentioned that the movement of the x-ray source and imaging device is synchronised so that the imaging device surface normal is perpendicular to the layer of interest, i.e. the panoramic layer.

The respondent held the view that USPRE disclosed on page 16, paragraph 5, that the transversal layer did not have to be strictly parallel to the direction of radiation, but could be just "close to parallel". In the Board's view, this possibility (mentioned in parentheses after the feature "parallel") addresses the fact that for a fan-type x-ray beam, as depicted in Figure 3, only the center ray will be strictly perpendicular to the panoramic layer, while the rays of the periphery of the beam will be only substantially perpendicular to it.

The jaw of a patient has a roughly horseshoe-shaped contour, which is clearly non-circular, particularly in its lateral portions. Hence, if a circular trajectory of the x-ray source and imaging device were used, as suggested by the respondent, the direction of the x-rays would not be perpendicular to the panoramic layers which follow the contour of the jaw. Moreover, the panoramic layers shown in Figure 7 of USPRE, as well as in Figure 3, are undoubtedly smooth curves without sharp turns or kinks, thus having continuous derivatives. Hence, since the x-rays are emitted perpendicularly to these curves, the x-ray source and imaging device will likewise move along a smooth trajectory.

2.2.6 The Board therefore finds that from the explicit direct and unambiguous disclosure of the movement of the x-ray source and imaging device in USPRE, the skilled person would conclude that the movement inevitably occurs along a non-circular spline. This is consequently no new information over what is explicitly disclosed. The respondent has identified no other feature in claim 1 of the main request which goes beyond the subject-matter disclosed in USPRE.

2.2.7 As the person skilled in the art derives the subject-matter of claim 1 of the main request directly and unambiguously, using common general knowledge, from the earlier previous application USPRE, D4 is not the first application within the meaning of Article 87(1) EPC and thus does not form the basis for a priority right.

Consequently, D4 is comprised in the state of the art within the meaning of Article 54(2) EPC.

2.3 Novelty

As it is undisputed that D4 discloses the subject-matter of claim 1 of the main request, the novelty requirement of Article 54(1) EPC is not fulfilled.

3. Auxiliary request 4

3.1 Article 123(2), (3) EPC

3.1.1 Claim 1 of auxiliary request 4 in its characterising portion defines the algorithm as calculating the layer of best focus disclosed on page 20, lines 20 to 28 of the application as filed with each of the steps shown in the flow diagram in Figure 8d. Consequently, the objection of an unallowable intermediate generalisation of the disclosure of original page 20, lines 20 to 28, as raised with regard to the subject-matter of claim 1 of the main request is hereby overcome.

3.1.2 Claim 1 of auxiliary request 4 explicitly includes the step of reconstructing the image of either a different panoramic layer or a part thereof. According to page 20, lines 23 to 27, selecting a part (98) of an image involves the selection of a region of interest by the dentist. Hence, contrary to the appellant's assertion, the step of selecting a region of interest, as included in the flow diagram of Figure 8d, is likewise contained in the step of reconstructing a part of the different panoramic image recited in claim 1.

3.1.3 Hence, the requirements of Article 123(2) EPC are complied with.

3.1.4 In claim 1 of the patent as granted (feature (e)), the shift-and-add algorithm is defined as composing a predetermined panoramic layer and a different panoramic layer. In claim 1 of auxiliary request 4, instead, the shift-and-add algorithm is defined as composing an image of these panoramic layers.

However, in the Board's view, the skilled person would naturally understand the "panoramic layers" defined in the patent as granted as the panoramic images of these layers. The Board therefore considers that specifying an image of these layers does not extend the scope of protection of the patent as granted.

Hence, the requirements of Article 123(3) EPC are complied with.

3.2 The appellant explicitly stated during the oral proceedings that there were no objections concerning the novelty and inventive step of the subject-matter claimed in auxiliary request 4. In particular, for this request the appellant did not contest the priority claim to document D4, admitting that D4 did not constitute prior art. The Board sees no objections either.