T 0295/10 01-03-2012

Reasons for the Decision

1. The appeal is admissible.

2. Sufficiency of Disclosure

2.1 The ground of lack of sufficient disclosure under Article 100(b) EPC was raised during the opposition proceedings by the appellant (then opponent) after the nine month opposition period set out in Article 99(1) EPC. The respondent submits that this ground should not be considered, since it was not invoked within the opposition period.

2.2 The opposition division has a discretion to admit late-filed grounds if it considers them to be prima facie relevant (see the Headnote of G 10/91). The opposition division reasoned that, in light of the arguments brought forward by the opponent, it was necessary to investigate the ground further (see point 3.1.3 of the contested decision). As far as the Board is concerned, there is nothing improper in the manner by which the opposition division exercised its discretion and decided to admit this late-filed ground into the proceedings. On closer examination, the opposition division did not consider the ground to prejudice the maintenance of the patent. However, given that the ground was dealt with in the contested decision, the appellant now has the right to challenge the view of the opposition division in the appeal proceedings.

2.3 The alleged lack of sufficient disclosure arises out of the definition in claims 1 and 2 that "the pressure to an inlet of the impact device is controlled inversely proportionally to the pressure to the inlet of the rotation motor", and in particular the meaning of the expression "inversely proportional".

In mathematics, the graph of two parameters varying inversely is a hyperbola. However, this is not the relationship shown in the embodiment presented in Figure 2 of the disputed patent, where it is shown to be linear. The appellant therefore argues that the meaning of "inversely proportional" is unknown, so that the skilled person does not know how to vary the rotation and impact pressures in order to achieve the effect of the invention.

2.4 The Board agrees with the view of the opposition division set out in point 4.2 on page 7 of the disputed decision that the meaning of the expression is that "when the pressure at the inlet of the rotation motor increases the pressure at the inlet of the impact decreases accordingly, ie not in an instantaneous manner as in the prior art acknowledged in the patent specification… in other words the more the rotation increases, the more the impact pressure is reduced".

2.5 The arguments put forward by the appellant go to show that the expression "inversely proportionally" and consequently the scope of protection provided by claims 1 and 2 are not clear. However, Article 84 EPC is no ground for opposition. In considering Article 100(b) EPC, the question is whether the invention has been sufficiently disclosed in the patent for a skilled person to be able to carry it out.

The embodiment in Figure 2 shows that when the rotation pressure increases beyond a given value (42), the pressure to the impact device decreases linearly to the collaring pressure (43). A skilled person is able to arrange the control system of a drilling device so that the effects shown in Figure 2 are achieved, and hence is able carry out the claimed invention. The Board concurs with the reasoning given in T 608/07 (at 2.5.2) that, in the context of Articles 83 and 100(b) EPC, it is not enough merely to show that an ambiguity in the claimed subject-matter exists, it is necessary to show that it deprives the skilled person of the promise of the invention. Given that the embodiment in Figure 2 allows the skilled person to put the invention into effect, the invention is not insufficiently disclosed within the meaning of Article 100(b) EPC.

3. Prior Art

3.1 The respondent agreed that the disclosure of prior art given in paragraph [0002] of the disputed patent is prior art according to Article 54(2) EPC and can thus be taken into consideration for assessing novelty and inventive step.

3.2 Japanese patent document D3 was filed with the notice of appeal, but is not part of the state of the art, as it was published after the priority date of the disputed patent. Japanese patent application D3a was published before the priority date, but was filed late in the opposition proceedings, together with English translation D3b. The opposition division concluded that application D3a corresponds to patent D3 and was state of the art under Article 54(2), hence admitted it into the proceedings (see paragraphs 1 to 3 on page 4 of the contested decision). The Board has no reason to question the discretion exercised by the opposition division and hence D3a and D3b will be considered in the appeal proceedings.

4. Novelty (Article 54 EPC)

4.1 The issue of novelty in respect of D3a was raised late in the opposition proceedings. The opposition division was of the view that D3a prima facie did not prejudice novelty, hence decided not to admit the ground. However, D3a was taken into consideration for the assessment of inventive step. This inevitably requires that differences, if any, between the claimed subject-matter and D3a have to be identified. Hence an assessment of novelty in the context of determining inventive step is unavoidable.

4.2 D3a discloses a method of controlling a rock drilling machine having rotary, feed and impact devices. According to this method, when the rotary pressure exceeds a given pressure P2, the impact pressure is lowered whilst the rotation pressure continues to increase (see Figure 3 of D3a and paragraph [0025] of D3b). This corresponds to controlling the pressure to the impact device "inversely proportionally" to that of the rotation motor, as is defined in the claims of the disputed patent (see points 2.3 and 2.4 above).

4.3 Paragraph [0025] of D3b also states that the thrust of the feed mechanism is lowered "at this instance". The appellant argues that this phrase does not refer to a specific moment, but to the time interval during which the impact pressure is reduced and the rotary pressure is increased.

Given that "instance" means case or example, it is clear that the expression "at this instance" is a mistake in translation, with the correct expression being "at this instant", which means at a particular moment or point in time. The Board therefore agrees with the view of the opposition division (see first paragraph on page 10 of the contested decision) that "at this instance" refers to the specific moment when the controller actuates valve 8 in order to lower the impact pressure. Consequently, D3a discloses the lowering of both the impact pressure and the feed pressure at the same time, ie when the rotation pressure reaches P2.

4.4 The appellant also argues that the wording of claim 1 encompasses the situation where the first and second values of the rotation pressure are the same.

4.5 As argued by the respondent and opposition division, by explicitly defining in the claim first and second predetermined values, it is clear that the values are to be distinguished from each other. Although the first and second predetermined values of claim 1 are different from each other, the wording does not, however, define which of the two is greater. The arrangement of D3a, whereby the impact and feed pressures are reduced at the same rotation pressure, does not fall within the definition given in claim 1, and hence the method defined in this claim is novel.

4.6 The appellant further submits that the device of claim 2 lacks novelty, since the control system of D3a is suitable for operating in the manner defined in the claims. In particular, the arrangement of Figure 4 shows two pressure switches (24) connected to the hydraulic line supplying the rotation device. Since these switches can be set to operate at different pressures, the impact and feed pressures can be reduced in accordance with different rotation pressures.

Figure 4 shows that the two pressure switches for the rotation control (24), along with the control of valves supplying the impact and feed devices (indicated as (27 and (28) respectively), are linked to a control panel (29). However, there is no disclosure in D3a that the control panel is programmed or set up so that the feed and impact pressures are reduced at different rotation pressures. Such an arrangement is a feature of the apparatus itself and not just of how it is used. It may or may not be the case that the control system of D3a can be modified easily to adjust the pressures as defined in the claims of the disputed patent, but the test for novelty is strict, and since the features of claim 2 are not directly derivable from D3a, the claimed device is novel.

5. Inventive Step (Article 56 EPC)

5.1 The starting point for the disputed invention is described in paragraph [0002] of the patent specification. According to the known method, pressure to the rotation device is kept constant up to a first predetermined value, after which the pressure to the feed motor is reduced. If the rotation pressure nevertheless continues to increase to a second predetermined value the pressure to the impact device is changed instantaneously to the collaring pressure.

5.2 The method of claim 1 differs from the known method by reducing the pressure to the impact device inversely proportionally to the rotation pressure instead of changing it instantaneously.

5.3 Starting from the known method, the problem to be solved as stated in the patent is how to reduce the risk of the rock drill jamming (see column 1, lines 27 to 29 and 33 to 36 of the patent).

5.4 The proposed solution is control the impact pressure inversely proportionally to the rotation pressure and thereby avoid an abrupt drop in pressure that can lead to jamming.

D3a discloses a method for controlling the impact pressure of a drilling device in response to rotational forces (see paragraph [0001] of D3b), hence is of interest to the skilled person. The aim of D3a is to control the impact pressure in view of reducing the shock waves that result from the hammering action of the drill (paragraph [0007] of D3b), and to prevent adverse effects when the rotational pressure increases in response to deteriorating drilling conditions (paragraph [0014] of D3b).

The solution taught in D3a is that, when a drilling defect is encountered, the impact pressure is lowered inversely proportionally to the rotation pressure (see paragraph [0025] of D3b and Figure 3 of D3a). In doing so, the effect described by the respondent, in which an abrupt reduction in impact pressure leaves a significant pressure in the hydraulic system that may cause jamming, is also avoided. Applying the teaching of D3a to the known method with a view to solving the objective problem results in the claimed method and device, hence there is a lack of inventive step.

5.5 The respondent argued that the skilled person would not consult D3a, as the teaching is to reduce both the impact and feed pressures on reaching the same rotational pressure.

The Board does not agree with the respondent's submission as, according to the known method that forms the starting point for the disputed invention, the feed and impact pressures are reduced at different rotational pressures in order to keep the rotational pressure substantially constant. The emphasis in D3a is on reducing the impact pressure in a certain way (paragraph [0001] of D3b), and the skilled person would not see the necessity of reducing the impact pressure at the same time as the feed pressure, which would forgo the advantage of the known method.