T 0774/15 25-11-2019

1. Admission of requests

1.1 Main request a, main request b, auxiliary request I a, and auxiliary request I b were filed during oral pro­ceedings before the board. These requests constitute therefore an amendment to the appellant's case after it has filed its grounds of appeal and may be admitted into the proceedings and considered at the board's discretion (Article 13(1) RPBA).

Auxiliary request I was filed with the statement set­ting out the grounds of appeal and may be held inad­mis­sible by the board in accordance with Article 12(4) RPBA.

1.2 In accordance with established case law, late-filed auxiliary requests are inadmissible if - prima facie - they do not overcome the outstanding objections under the EPC or give rise to new objections (see Case Law of the Boards of Appeal of the EPO, 9th edition 2019, sections V.A.4.4.2 a) and 4.5.1).

1.2.1 Claim 1 of main request a differs from claim 1 of the main request in that features 1.5' and 1.8' are re­placed by features 1.5'' and 1.8'', respectively. Claim 1 of auxiliary request I a also comprises features 1.5'' and 1.8''.

The appellant was of the opinion that the amendments in the features 1.5'' and 1.8'' in relation to the "UV radiation output" and the "nominal input power" were based on the application as filed (page 2, line 19; page 3, line 13; page 7, last line; page 8, third from last line).

1.2.2 The board notes that the sentence on page 2, lines 18 and 19 of the description of the application re­lates to the ratio of the radiation output and the lamp input power (i. e. the "lamp efficiency") rather than the ratio of the radiation output and the maximal radi­a­tion output as claimed in feature 1.5''. Further­more, the sentence does not refer to the UV spectral band as claimed but to the UV-C spectral band.

Moreover, "nominal input power" is not explicitly men­tioned anywhere in the application as filed, as ad­mitted by the appellant. There is also no indication in the application that the various occurrences of the expression "maximal input power" cited by the appellant are intended to refer to the nominal input power, since the expression may well be understood in different ways (see point 2.4.2 below).

Hence, there are doubts whether the subject-matter of features 1.5'' and 1.8'' is directly and unambiguously derivable from the application as filed.

Consequently, prima facie, main request a and auxiliary request I a give rise to a new objection under Article 123(2) EPC concerning added subject-matter. These re­quests are therefore not admitted into the proceedings (Article 13(1) RPBA).

1.3 Main request b constitutes a reversion to the patent as granted. Even though the request is submitted at a late stage of the proceedings the board accepts that it poses no additional work and that the respondent and the board are in a position to deal with the request at the oral proceedings.

Auxiliary request b ­is therefore admitted into the proceedings (Article 13(1) RPBA).

1.4 Claim 1 of auxiliary request I differs from claim 1 of the main request essentially in comprising the addi­tion­al features 1.10 and 1.11. Claim 1 of auxiliary request I b also contains these features.

The appellant argued that it had filed auxiliary re­quest I only at the appeal stage as it had relied on the technical understanding that the claimed subject-matter was new over document D1. This had been con­firmed by the preliminary opinion of the opposition division.

1.4.1 However, the board is of the opinion that a party can­not rely on the fact that its technical under­standing of matters in dispute will prevail during opposition proceedings. Moreover, a patent proprietor should for­mulate fallback positions at the earliest possible stage in order to allow the procedure to proceed in an efficient manner.

In the present case, document D1 had been filed with the notice of opposition. The fallback position of aux­iliary request I could therefore have been filed al­ready with the patent proprietor's reply to the notice of opposition. At the latest such a request should have been submitted during the oral proceedings before the opposition division, especially since the patent pro­pri­etor was explicitly asked during these proceedings whether it wished to do so (see point 4 of the minutes of the oral proceedings).

Admitting auxiliary request I into the appeal pro­ceedings might well compel the board either to give a first ruling on critical issues such as whether the subject-matter of the additional features is new and involves an inventive step, which runs counter to the purpose of appeal proceedings to review first instance decisions, or to remit the case to the opposition divi­sion, which is contrary to procedural economy. In order to forestall these unsatisfactory options, Arti­cle 12(4) RPBA provides the board with the discre­tionary power to hold inadmissible requests which could have been presented in the first-instance proceedings.

Auxiliary re­quest I is therefore not admitted into the proceedings (Article 12(4) RPBA).

1.4.2 Auxiliary request I b with independent claim 1 which also comprises features 1.10 and 1.11 constitutes an alternative fallback position that is similar to the fallback position of auxiliary request I. Since auxil­iary request I b was only filed at the oral proceedings before the board, the considerations mentioned under point 1.4.1 above in relation to auxiliary request I apply all the more to auxiliary request I b.

Consequently, auxiliary re­quest I b is not admitted into the proceedings, either (Article 13(1) RPBA).

2. Main request - clarity

2.1 The respondent argued that the amendments in features 1.5' and 1.8' of claim 1 of the main request were not clear, contrary to the requirements of Article 84 EPC 1973.

2.2 The board notes first that the respondent's objections under Article 84 EPC 1973 exclusively concern the amend­­­­ments effec­ted in relation to granted claim 1, namely those contained in features 1.5' and 1.8', and may therefore be examined in the present opposition appeal proceedings in accordance with the principles set out in the decision G 3/14 of the Enlarged Board of Appeal. This was not contested by the appellant.

2.3 Article 84 EPC 1973 stipulates that the claims define the matter for which protection is sought and that they must, inter alia, be clear.

This requirement serves the purpose of ensuring that the public is not left in any doubt as to which sub­ject-matter is covered by a particular claim and which is not. A claim which does not unambiguously allow this distinction to be made cannot be considered clear with­in the meaning of this Article (see decisions T 728/98, point 3.1 of the Reasons; T 1399/11, point 1.6 of the Reasons). An ambiguity of the claimed subject-matter may in particular arise when a claim contains terms or expressions which can be under­stood in various differ­ent ways.

2.4 In the present case the contentious expressions in this respect are "radiation output" (feature 1.5') and "max­i­mal input power" (feature 1.8') of claim 1 of the main request.

2.4.1 The appellant was of the opinion that the expression "radiation output" specified in feature 1.5' defined the emitted radiant flux and that it was not necessary to specify in the claim the wavelength of the radiation output.

The board notes that this expression is not further de­fined in claim 1 of the main request and that, in par­tic­ular, there is no indication con­cerning the spectral charac­teristics of the radiation.

The claim does not specify that the lamp system is adapt­ed for a particular application, either. Con­cern­ing the possible use of the claimed low-pressure mer­cury vapour discharge lamp as a fluorescent lamp the patent specification contains the following statement (see paragraph [0002]):

"In low-pressure mercury vapor discharge lamps, mer­cury constitutes the primary component for the generation of ultraviolet (UV) radiation. A lumi­nescent layer comprising a luminescent material, for example a fluorescent powder, may be present on an inner wall of the discharge vessel to convert UV radiation to radiation of other wavelengths, for example, to UV-B and UV-A radiation for tanning purposes or to visible radiation for general illumination purposes. Such discharge lamps are therefore also referred to as fluorescent lamps."

Mercury is described as constituting merely the "pri­mary compo­nent" for the generation of UV radiation in view of the fact that other components generating UV radiation may be present in the lamp. In fact, accord­ing to claim 1 of the main request the filling of the discharge vessel does not only contain mercury but also a rare gas, which may also contribute to the radiation emission of the discharge lamp.

On the other hand, according to claim 13 of the main request the lamp system of claim 1 of the main request is used for disinfection of water, waste water or air. In relation to this use as a germicidal lamp the patent specification contains the following remarks (see para­graph [0003]):

"Low-pressure mercury vapor discharge germicidal lamps predominantly generate UV-C radiation, and these types of lamps are used for disinfection of water and air, disinfection of foods, curing of inks and coatings, and destroying of pollutants in water and air. The principal radiation that is generated in such lamps has a wavelength of 254 nm, which prevents the growth of, for example, moulds and bacteria."

The reference to the "principal radiation" generated in such lamps having a wavelength of 254 nm implies that other spectral lines are also present. Indeed, low pres­­sure mercury vapor discharge lamps are known to have a further emission line in the UV-C spectral band at a wavelength of 185 nm.

In view of the above, the skilled person is left in doubt as to what is meant by the claimed "radiation output", in particular whether it refers to the emis­sion at a particular wavelength, namely at a wavelength of 254 nm and/or 185 nm, in a particular band of wave­lengths, namely the UV-C or UV band, or indeed in the entire radiation spectrum.

Feature 1.5' of claim 1 of the main request is there­fore not clear.

2.4.2 Concerning feature 1.8' the appellant argued that the expression "maximal input power" denoted the nomi­nal input power of the lamp and this feature defined the amalgam to be positioned in a relatively cool re­gion of the lamp.

It is first to be noted that there is no indication in claim 1 of the main request that the "maximal input power" defined in feature 1.8' of that claim denotes indeed the nomi­nal input power.

The board agrees with the appellant insofar as the expression "maximal input power" may well refer to the nominal input power. However, the expression may also be understood as denoting the maximum power at which the discharge lamp can be operated without being de­stroyed. Furthermore, the expression may be under­stood in the context of feature 1.8' as referring to the maximal input power at which the discharge lamp can be operated without the amalgam exceeding the maximum value of its optimal temperature range. The skilled person is thus left in doubt as to the meaning of this expression.

Feature 1.8' of claim 1 of the main request is there­fore also not clear.

2.5 In view of the above claim 1 of the main request does not fulfill the requirements of Article 84 EPC 1973.

3. Main request b - novelty

3.1 The opposition division held in the contested decision that claim 1 of main request b (i. e. granted claim 1) lacked novelty over document D1 (see point 1.2 of the Reasons).

3.2 Document D1 discloses (see D1, Figure 1; page 3 of the translation D1d of document D1) a lighting apparatus comprising a lighting power supply 8 and a fluorescent discharge lamp 1 with a first elec­trode 2 and a second electrode 4. An amalgam 3 is provided adjacent to the first electrode 2 and is heated when the electrode 2 is preheated. Winding N2 of a transformer 5 is connected to the first electrode 2 and functions as a preheating winding for preheating this electrode 2. A primary wind­­ing N1 of the transformer 5 is connected to a triac 6 and forms a circuit that energizes the preheating wind­ing N2 when the triac 6 is turned on. A lamp vol­tage detection circuit 7 is connected to the discharge lamp 1 in parallel, a Zener diode ZD of the circuit 7 being connected to a connection point a between resis­tors R1 and R2, and a gate G of the triac 6 being con­nected to the Zener diode ZD. When the lamp voltage is detected by the lamp voltage detection circuit 7 to have a high lamp voltage in dimming (e. g. 60% dimming relative to the fully-on state) this is detected by the resistors R1 and R2 of the lamp voltage detection cir­cuit 7 and the gate G of the triac 6 is triggered. Con­sequently, the triac 6 is turned on, the primary wind­ing N1 of the preheating transformer 5 energizes the preheating winding N2 and the first electrode 2 is pre­heated.

3.3 The contested features of claim 1 of main request b are features 1.5, 1.6, and 1.8. It is common ground between the parties that the other features of the claim are disclosed in document D1.

Indeed, using the wording of claim 1 of main request b document D1 discloses a lamp system (lighting apparatus) comprising a low-pressure mercury vapor discharge lamp (fluorescent discharge lamp 1), the lamp comprising:

- at least one discharge vessel enclosing, in a gas-tight manner, a discharge space provided with a filling of mercury and a rare gas, the discharge vessel having a first end section and a second end section,

- a first electrode (2) arranged at the first end section and a second electrode (4) arranged at the second end section for maintaining a discharge along a discharge path between the first electrode and the second electrode,

- an electronic circuit (power supply 8, transformer 5) arranged to generate an electrical discharge current for maintaining the discharge, and an electrical heating current for heating the heating element (first electrode 2), independently of the electrical discharge current,

- wherein the lamp system further comprises

a control circuit (vol­tage detection circuit 7, triac 6) for generating at least one control signal to activate the electronic circuit to generate the electrical heating current in dependence on at least the dimming level of the lamp.

3.4 In relation to features 1.5 and 1.6 the appellant was of the opinion that document D1 merely disclosed that the mercury vapour pressure was kept at an appropriate value to prevent the lamp from going out in dimming, but not that the amalgam was kept within its optimal temperature range.

3.4.1 The board notes first that in claim 1 of main request b there is no indication about what is meant by the claimed "optimal tempera­ture range".

The patent specification contains the following state­ment in this regard (see paragraph [0004]):

"In the description and claims of the current in­ven­tion, the designation 'optimal temperature range' for an amalgam is used to refer to the tem­perature range where the mercury vapor pressure is such that the radiation output of the lamp is at least 90 % of the maximal radiation output, i.e. under operating conditions where the mercury vapor pressure is optimal."

Even though there is uncertainty concerning the spec­tral characteristics of the "radiation output" as indi­cated under point 2.4.1 above, it is evident from this state­ment that a temperature in the "optimal tempera­ture range" will lead to a mercury vapour pressure in the discharge vessel that is "close to the optimal va­pour pressure" leading to the maximal radiation output.

Indeed, the skilled person understands that it is the mercury vapour pressure that is the relevant quantity in this respect, its optimal value representing a bal­ance between the number of excitable mercury atoms and the absorption of the resonance radiation by these atoms. Since there is no further indication in claim 1 of main request b concerning the "optimal temperature range", e. g. by providing numerical values of related quantities as in the above citation, it does not follow from the claim how close the mercury vapour pressure has to be to the optimal value implying that the ex­pression "optimal temperature range" has to be under­stood in rather broad terms. This is especially the case since the mercury vapour pressure in the discharge vessel does not only depend on the temperature of the amalgam, but - when the discharge vessel contains ex­cess mercury - crucially on the temperature of the cold­est spot on the wall of the vessel which determines the mercury vapour pressure to be equal to the satura­tion pressure for that temperature (see page 71 of document D12, which represents the skilled person's common general knowledge).

3.4.2 Document D1 contains the following statement (see the translation D1d, page 3, last line - page 4, line 3):

"Since this preheating of the amalgam-side elec­trode 2 causes the amalgam 3 provided adjacent to the electrode 2 to also be heated, a temperature of the amalgam is increased to an appropriate tempera­ture without insufficiently heating, and a mer­cury vapor pressure is maintained at an optimal value."

This passage is translated in essentially the same way in the other submitted translations D1a (see page 2, paragraph 2), D1g (see page 5, lines 27-32), and D1e (see page 3, last line - page 4, line 3) of document D1. The passage, in particular the reference to the optimal value of the mercury vapour pressure but also the reference to the appropriate temperature of the amalgam, is considered a direct and unambiguous dis­closure of features 1.5 and 1.6 of main request b when they are understood as indicated under point 3.4.1 above.

3.5 Concerning feature 1.8 the appellant argued that it was merely disclosed in document D1 that the amalgam 3 was provided in the vicinity of the electrode 2. However, there was no disclosure in D1 where the amalgam 3 was precisely located. In particular, this could not be deduced from the schematic Figure 1, either.

The board agrees with the opposition division that in view of technical considerations it is implicitly dis­closed in document D1 that the amalgam 3 is located outside the discharge path (see last paragraph of point 1.2.3 of the Reasons). As pointed out by the opposition division, the amalgam 3 would otherwise be heated up in an uncontrolled manner. However, this would be contrary to the teaching of D1 according to which the amalgam 3 is heated in a controlled fashion by means of the lamp voltage detection cir­cuit 7, triac 6, transformer 5, and first electrode 2 in order to keep the amalgam at an appropriate temperature as discussed above. Further­more, if the amalgam were located in the discharge path the electric discharge between the electrodes through the ionized gas and hence the light emission would be disturbed or disrupted.

This understanding is confirmed by the schematic repre­sentation in Figure 1 of document D1, which shows the second electrode 4 at a distance above the first elec­trode 2, whereas the amal­gam 3 is shown to be located below the first electrode 2, i. e. outside the direct path connecting the two electrodes 2 and 4.

Feature 1.8 is therefore considered to be disclosed in document D1.

3.6 Consequently, the subject-matter of claim 1 of main request b (i. e. granted claim 1) is not new over document D1 (Article 100(a) EPC 1973 in combina­tion with Article 52(1) EPC and Article 54(1) and (2) EPC 1973).

4. Conclusion

Since the main request does not meet the requirements of the EPC (lack of clarity), a ground of opposition (lack of novelty) prejudices the maintenance of the pa­tent with claims as granted according to main request b and main request a, auxiliary re­quest I, aux­iliary request I a, and auxiliary re­quest I b are not ad­mitted into the proceedings, the opposition divi­sion's decision revoking the patent is to be confirmed. Con­sequently the appeal has to be dis­missed (Article 101(2) and (3)(b) EPC and Article 111(1) EPC 1973).