T 0747/22 (Aspirated Smoke Detectors/LIFE SAFETY DISTRIBUTION AG) 07-10-2024

1. Admissibility of the appeal

The appeal meets the requirements of Articles 106 to 108 EPC and Rule 99 EPC. It is therefore admissible.

2. Main request - Inventive step

2.1 The ground for opposition under Article 100(a) EPC prejudices the maintenance of the opposed patent because the subject-matter of claim 1 according to the main request does not involve an inventive step within the meaning of Article 56 EPC.

2.2 Closest prior art

The board is satisfied that the embodiment of figure 2a of D2 as modified in accordance with paragraph [0035] and figure 6a of D2 is a suitable starting point for the assessment of inventive step.

2.3 Distinguishing features

The appellant argued that features A1.3 and A1.9 are the only distinguishing features. The respondent argued that also features A1.4 to A1.6 and A1.8 to A1.11 are not disclosed in document D2, without clearly specifying which of its embodiments is considered in this analysis.

The board is convinced that the embodiment of figure 2a modified in accordance with paragraph [0035] and figure 6a discloses feature A1.6, viz. an ambient condition detector (20-3) including a multi-channel aspirating smoke sensor having primary and redundant smoke sensing chambers coupled to the first ambient air input network and the second ambient air input network respectively. The reasoning in the reply to the statement setting out the grounds of appeal on page 11 only deals with the embodiments in figures 1 and 5 of D2. Moreover, the respondent's reasoning hinges on the expression "redundant". The board is not convinced that this expression in the context of the claims and also of the application as a whole would be understood by a skilled person in any other way than meaning a second smoke sensing chamber. The board acknowledges that the smoke sensing chamber is redundant in the sense that it is also able to detect the presence of smoke. It is not redundant in the strict sense of the word because it is also required in order to localise the origin of the smoke. The second detector in the "hybrid" embodiment of figure 2a modified in accordance with paragraph [0035] is redundant in exactly the same sense.

Furthermore, the board is convinced that D2 discloses feature A1.11 in paragraph [0034], in particular its last sentence, in the context of the embodiment in figures 2a/6a and paragraph [0035].

The distinguishing features are therefore the following

A1.3|a second ambient air input network (14) coupled to a second fan (20-2) different than the first fan, wherein the second ambient air input network includes a second plurality of spaced apart intake points (18)(D2 discloses only one fan)|

A1.4|wherein the first ambient air input network and the second ambient air input network aresubstantially identical(there is no direct and unambiguous disclosure of the pipe networks being essentially identical)|

A1.5|and wherein the first fan and the second fan both operate at a common speed;(D2 discloses only one fan)|

A1.8|and control circuits (22) that are configured to calculate a pre-recorded series of transport times correlated to the second plurality of spaced apart intake points based on a power value of the second fan and a pipe geometry of the second ambient air input network and store the pre-recorded series of transport times as a table in a memory device (22d)(D2 does not explicitly mention a power value of a fan)|

A1.9|wherein the control circuits are configured to activate the second fan to draw in ambient airwhen smoke aspirated from the first ambient air input network triggers an alarm associated with the ambient condition detector,(D2 discloses only one fan)|

A1.10|wherein the control circuits, simultaneously with activation of the second fan, are configured to start the timer to count a transport time between the activation of the second fan and when the smoke aspirated from the second ambient air input network reaches the ambient condition detector(D2 discloses only one fan)|

2.4 Technical effect and objective technical problem

The technical effects associated with these distinguishing features are the following.

No particular technical effect is derivable from the opposed patent associated with having two fans instead of just one combined with a pipe switching device (feature A1.3). Two fans functionally operated as claimed in features A1.3 and A1.9 are equivalent to the pipe switching device of D2 and achieve the same technical effect of being able to measure the transport time of smoke in the case of fire by providing a defined start time.

The respondent argued in the letter dated 10 September 2024 and at the oral proceedings that the second fan remained off most of the time. Therefore the fan remained in pristine condition. Small deviations in fan power had a large impact on the accuracy of smoke localisation. The localisation was effected via fluid dynamic calculations. Those calculations were only as reliable as the parameters entering them. The localisation was therefore more reliable over a long period of time by using a second fan which according to feature A1.3 remained in pristine condition.

It is not necessary to discuss in detail whether this effect is achieved or not, as will be apparent in the following. The board concluded that even if this effect is achieved, it is a bonus effect (see section2.5 below).

Providing substantially identical air intake networks (feature A1.4) and running the fans at a common speed (feature A1.5) also does not achieve any particular technical effect derivable from the opposed patent. It is apparent to a skilled person that these two features provide for simplicity of the system because more similar components can be used.

Concerning feature A1.8, this feature merely lists an input value (fan power value) that is required to determine the transport time in a pipe intake system based on calculations. No particular technical effect is associated with mentioning this input value.

Concerning features A1.9 and A1.10, they are distinguishing features merely as a consequence of D2 not disclosing a second fan. The claimed second fan and the way it is operated is at least functionally equivalent to the pipe switching device (10) of D2, figure 2a and the way it is operated (even if it may additionally make localisation of smoke more reliable over a long time). The technical effect associated with these two features is therefore the same as that already realised by the pipe switching device of D2, namely providing a defined starting time from which the transport time can be measured to localise the aperture through which smoke enters.

It is apparent that there is no synergy between the individual distinguishing features except for features A1.3 (the partial feature that the second air intake network is coupled to the second fan), A1.9 and A1.10.

2.5 The partial objective technical problems are therefore:

- to provide a simple implementation (related to features A1.4 and A1.5)

- to provide a detail of determining the transport time (A1.8), and

- to provide an alternative to the pipe switching device (features A1.3, A1.9 and A1.10)

Concerning the last partial problem associated with the technical effects realised by a second fan, the board notes that a single feature may cause several distinct technical effects, and hence also solve different objective technical problems. If a skilled person arrived at the invention as claimed in an obvious manner because of one of those technical problems, the other technical effects would merely be bonus effects that could not, by virtue of their mere existence, render the subject-matter non-obvious; see also Case Law of the Boards of Appeal, 10th edition, July 2022 ("CLBA"), I.D.10.8. The board concludes that the present case falls in this category. In view of the assessment of the solution by the board, it is not necessary to formulate a further partial problem relating to the technical effect of improved long term reliability of the determination of the transport time as adduced by the appellant.

2.6 The respondent further argued that the technical problem as formulated in the decision under appeal of improved smoke detection was in fact correct. The smoke detected in the second smoke sensing chamber had a higher concentration and allowed therefore a more precise determination of the transport time, and hence a more precise localisation of the smoke.

The board is not persuaded. The argument of the respondent concerning the technical effect of improved smoke detection is described with a continuous aspiration in a single pipe and reversal of the fan direction in mind (such as the embodiment in figures 1 or 5 of D2). This is, however, not the working principle of the closest prior art, namely the embodiment of figure 2a of D2. Rather, at the point in time when the pipe switching device is activated in figure 2a of D2, the smoke concentration has increased just as in the respondent's example given in the reply to the appeal, and the slope of the detection curve will be steeper, similar to that indicated in the reply. The board also has serious doubts that the small time gained by a steeper detection curve in the second detector can compensate for the additional transport time required, but this does not need to be discussed further since it concerns other embodiments of D2 than that chosen as closest prior art.

2.7 Assessment of the solution

The claimed solution to the first partial problem is obvious. It would have been obvious to a skilled person to choose the two air intake pipe networks to be essentially identical for simplicity and because then no further different components are necessary. This amounts merely to spelling out something that is not explicitly mentioned in document D2. Modifying the system of D2 according to features A1.4 and partial feature A1.5 was therefore obvious.

The solution to the second partial problem is also obvious. D2 already discloses that the expected transport times from an intake hole to the smoke detector can be calculated; see paragraph [0016]. According to D2 this requires knowledge of the fluid speed in the pipe segments. It would be immediately apparent to the skilled person that this speed would depend on the power value of the fan. The opposed patent only provides a basic sketch of the required calculation in paragraph [0031], limiting itself to merely enumerating the required input parameters. This confirms the board's assessment that the underlying fluid dynamic calculations are part of the normal capabilities of the skilled person. Enumerating a required input value for a calculation which a skilled person can perform due to their routine capabilities amounts to merely filling a gap in the teaching of the prior art document D2 in an obvious manner.

Moreover, the solution to the third partial problem is obvious. It would have been obvious to a skilled person that a second fan connected to the second ambient air input network as claimed in partial feature A1.3, and operated according to feature A1.9, as well as a timer and transport time analysis logic according to feature A1.10 are functionally equivalent to the pipe switching device. This arrangement provides for the same functionality when it comes to providing a defined starting time in the determination of the transport time of the smoke. This arrangement has the advantage of not requiring the pipe switching device, but at the same time the disadvantage of requiring a second fan. The board considers such a choice to be part of the routine practice of a skilled person involving only the balancing of immediately apparent advantages and disadvantages and the consideration of obvious alternatives. Since a skilled person would have arrived at the solution to the third partial problem as formulated above in an obvious manner, it is not necessary to examine if a solution to the problem of improved long term reliability of transport time determination would have been obvious or not. This is merely a bonus effect that a skilled person would achieve anyway by providing the claimed alternative, whether they are aware of the potential advantage or not.

Once the skilled person has opted for the alternative of a second fan, running both fans at a common speed was merely an implementation of an obvious design choice. Feature A1.5 is therefore obvious.

The board wishes to emphasise again that a consideration of the features separately in the preceding manner is justified because none of them interact technically in such a way as to require a consideration of any of their combinations.

2.8 The counter-arguments of the respondent did not persuade the board.

In the reply to the appeal on page 15, the respondent relied mainly on the objective technical problem of smoke localisation in a timely manner (because no fan reversal to empty the pipe was required). This is, however, not the correct formulation of the objective technical problem, because it is already solved by the closest prior art embodiment of figure 2 modified in accordance with paragraph [0035] and figure 6 of D2.

Moreover, the respondent relied on the further problem identified in the decision under appeal, namely that continuous smoke detection was possible. However, this technical effect is also achieved by the modified embodiment of figure 2 in D2, and hence cannot establish the presence of an inventive step.

The respondent also argued on page 16, second paragraph, that D2 disclosed 10 embodiments but none of them showed all claim features in combination. This argument equates inventive step with novelty, which is unpersuasive.

The reasoning on pages 17 and 18 of the reply concerning a higher smoke concentration in the second pipe/fan/detector branch relies on a technical effect that is also achieved by the modified embodiment of figure 2 in D2 and hence cannot establish the presence of an inventive step.

2.9 It follows that the ground for opposition under Article 100(a) EPC in conjunction with Article 56 EPC prejudices the maintenance of the patent as granted.

3. Fourth auxiliary request - Inventive step

3.1 The subject-matter of claim 1 according to the fourth auxiliary request involves an inventive step within the meaning of Article 56 EPC.

3.2 Claim 1 of the fourth auxiliary request has the features of claim 1 of the main request and in addition the feature

"wherein the second fan is automatically and periodically activated".

3.3 Closest prior art

The embodiment of figure 2 as modified in accordance with paragraph [0035] of D2 is the closest prior art also for claim 1 of the fourth auxiliary request.

3.4 Distinguishing feature

In addition to the distinguishing features identified in the discussion of the main request, the additional feature is a further distinguishing feature.

This was not contested by the appellant.

3.5 Technical effect and objective technical problem

According to paragraph [0034] of the opposed patent "[t]o avoid dust/contamination or blockage in the RPN, it could be useful to automatically and periodically activate the RCH fan 20-2. In this way, airflow will be checked with the standard equipment of ASD. Eventual malfunction of the RPN or RCH fans can be detected and proper maintenance can be ordered."

A further technical effect beyond those mentioned in the discussion of the main request is therefore to avoid dust, contamination or blockage or to monitor malfunction of the fans. The board can accept that the pipe network used for transport time determination is not continuously in use. Therefore the pipes can gather dust and contamination. Furthermore, a blockage would go unnoticed if the second fan were not operated.

A further partial technical problem is therefore to provide for a more reliable transport time detection in the second pipe network.

3.6 Assessment of the solution

3.6.1 D2 does not mention or address the further objective technical problem or suggest the claimed solution to it.

The appellant argued on page 7 of the letter dated 15 February 2023 that a skilled person would consider an intermittent periodic operation of the second fan in order to ensure that both pipe networks did not age differently.

In the board's view this is no more than an unproven assertion and therefore not persuasive.

3.6.2 The appellant submitted further for the first time at the oral proceedings before the board that the European standard EN 54-20 required an aspirated smoke detection system to possess an airflow monitoring function which recognises interruptions of air flow and reports them within 300 seconds. Such a standard was part of the common general knowledge at the filing date of D2. Without airflow monitoring, an aspirating smoke detector would not receive approval. This applied to both pipe networks as claimed.

The respondent argued that this was an amendment to the appeal case presented after notification of the communication according to article 15(1) RPBA for which there were no exceptional circumstances justified by cogent reasons.

The board agrees with the respondent. The appellant has not shown such exceptional circumstances as required by Article 13(2) RPBA. For this reason alone, the industry standard offered as evidence is not taken into account and the alleged facts remain unproven.

4. Fourth auxiliary request - amendments

4.1 Claim 1 of the fourth auxiliary request does not contravene Article 123(2) EPC.

4.2 The appellant objected that claim 1 contained added subject-matter going beyond the content of the application as filed. The appellant argued that the purpose of the detector of claim 1 was to localise the smoke. Due to the consequent use of the wording first and second ambient air input networks, first and second pluralities of spaced apart intake points, and first and second fans, a skilled person would interpret claim 1 in such a manner that these elements were necessary for localising smoke. In contrast to this, a skilled person would interpret the deviating use of the wording "primary and redundant smoke sensing chambers" in feature A1.6 as meaning that the "redundant" smoke sensing chamber was not necessary for localising smoke. However, the redundant smoke sensing chamber was not simply a backup, but was itself required to localise the smoke, since it was coupled to the second air intake network. A skilled person would interpret claim 1 such that the primary as well as the redundant smoke sensing chambers were both connected to the first and to the second ambient air input network, and the redundant smoke sensing chamber was not necessary for localising smoke.

This argument does not persuade the board. Firstly, the board is persuaded by the respondent's argument that the appellant's interpretation of claim 1 is not correct (see reply, page 5, second paragraph). Feature A1.6 reads

"an ambient condition detector (20-3) including a multi-channel aspirated smoke sensor having primary and redundant smoke sensing chambers coupled to the first ambient air input network and the second ambient air input network respectively".

The word "respectively" at the end of this feature clearly indicates that the primary smoke sensing chamber is coupled to the first ambient air input network and that the redundant smoke sensing chamber is coupled to the second ambient air input network. The plural of "chambers" is required because the feature refers to two chambers in total.

Secondly, a skilled person would clearly understand from the wording of claim 1 alone, in particular features A1.9 to A1.11, that the "redundant" smoke sensing chamber is used to localise smoke, irrespective of the term "redundant".

This information is directly and unambiguously derivable from paragraph [0014] of the description as originally filed, which discloses that the aspirated smoke detector has primary and redundant smoke sensing chambers. It is apparent from this paragraph that the word redundant is used in order to distinguish the claimed subject-matter from the prior art in which, when smoke is detected, the fan is reversed to clear a single air input pipe of smoke, then a timer is started, and then smoke is aspirated again. The term "redundant" in this paragraph, as well as in claim 1 of the fourth auxiliary request as explained above, is not to be understood as meaning simply a back-up smoke sensing chamber assuring functionality if the primary smoke sensing chamber fails. Rather, the primary smoke sensing chamber is the one that first detects the presence of smoke, and the redundant smoke sensing chamber is used to redundantly detect smoke but additionally to localise it.

The appellant's argument amounts to arguing that the term "redundant" has to be understood differently in the context of claim 1 and of the description. The board considers this approach to be unpersuasive per se and also not to be correct in the circumstances of the case.

4.3 Moreover, the appellant argued that it was not originally disclosed that an ambient condition detector included a multi-channel aspirating smoke sensor having primary and redundant smoke sensing chambers. The expression "ambient condition detector" appeared only in original claim 1, but not in the originally filed description.

This argument does not persuade the board because it looks at the description in isolation as a potential original disclosure. Rather, the respondent correctly referred to original claim 1 and its dependent claim 9. It is apparent that the respondent's reference on page 4 of the reply to original claim 5 was in fact intended to be to claim 9.

Original claim 1 discloses an aspirated detector system comprising an ambient condition detector. Original claim 9 disclosed that the ambient condition detector comprised one of a smoke detector, or a gas sensor. Moreover, the respondent referred to original paragraph [0008] of the A2 publication (paragraph [0014] of the original description), which discloses that "[i]n view of the redundancy of the pipe networks, the aspirated smoke detector (ASD) has primary and redundant smoke sensing chambers". The passages adduced by the respondent therefore contain an original disclosure of an aspirated smoke detector system comprising an ambient condition detector including primary and redundant smoke sensing chambers. The respondent argued that it followed from the fact that the aspirated smoke detector had primary and secondary sensing chambers that it was a multi-channel sensor. In this respect, since the respondent referred to claim 9, it is justified to look at the original dependent claim 10 directly following it, which discloses that the "detector comprises a multi-channel aspirated smoke sensor".

4.4 The appellant also objected to the feature "calculate a pre-recorded series of transport times" in feature A1.8, and "pre-recorded series of transport times stored in the memory device" in feature A1.11 as containing subject-matter going beyond the disclosure as originally filed. The appellant argued that it was not originally disclosed

(a) that a previously recorded series of transport times is recalculated,

(b) that it is the control circuits that are configured to calculate the pre-recorded transport times

(c) that the calculation is based on a power value of the second fan and a pipe geometry of the second ambient air input network.

This argument does not persuade the board. The respondent correctly referred to paragraph [0027] and figure 6 of the A2 publication (which has the same content as the originally filed documents). Paragraph [0027] discloses that the transport times can be obtained by calculating them and storing them in the memory of the device.

The appellant's interpretation of the expression "calculate a pre-recorded series of transport times" (see point (a) above) is based on a technically implausible understanding. Claim 1 of the main request specifies that both pipe networks and fans are substantially identical and that the fans operate at the same speed. It would therefore not make any technical sense to recalculate transport times, experimentally determined for the first input network, again for the second input network. Rather, a skilled person would simply understand the word "pre-recorded" as a label for the initially stored calculated transport times. This label is correct at any point in time after the initial storage.

Concerning point (b) above, the appellant again does not take the entire disclosure into account, notably claim 13, but merely the description. The argument is therefore unsuitable to demonstrate that there is no direct and unambiguous disclosure.

Lastly, concerning point (c) above, it has to be stressed again that a skilled person strives for a technically meaningful interpretation of the subject-matter of the claim. It is clear from the claim wording itself that the second ambient air input network is used for locating the origin of the smoke via the determination of the intake point. A skilled person therefore immediately understands the disclosure in such a manner that any calculation of transport times has to be based on the values of the second ambient air input network.

5. Fourth auxiliary request - clarity

5.1 The clarity of claim 1 of the fourth auxiliary request is not open to examination, see decision G 0003/14.

5.2 The appellant objected that claim 1 did not meet the requirements of Article 84 EPC because the pipe networks were defined as being at the same time "independent" and also "interconnected".

5.3 The objected feature

"wherein each of the first ambient air input network and the second ambient air input network includes a respective interconnected set of conduits perforated to respectively form the first plurality of spaced apart intake points and the second plurality of spaced apart intake points"

is taken from granted dependent claim 8.

According to decision G 0003/14 (headword), in considering whether, for the purposes of Article 101(3) EPC, a patent as amended meets the requirements of the EPC, the claims of the patent may be examined for compliance with the requirements of Article 84 EPC only when, and then only to the extent that the amendment introduces non-compliance with Article 84 EPC.

Since the objected feature results from the combination of granted claims, it does not "introduce" a non-compliance within the meaning of decision G 0003/14.

Irrespective of that, the objection is based again (see point 4.2 for comparison) on an erroneous understanding of the word "respective". The meaning of this feature is merely that each of the ambient air input networks is built from an interconnected set of conduits, not that the two air input networks have a connection between them.