T 0994/08 19-02-2010

Reasons for the Decision

1. Occupant restraint systems in automobiles commonly require activation, such as inflation of an airbag or pre-tensioning of a safety belt. In order for the restraint to be effective the timing of the activation following an impact is critical. Apparatus for controlling the activation commonly comprises a sensor (designated "first" in the present file) mounted close to the centre of the vehicle for measuring deceleration during an impact and a control unit which receives a signal from the sensor. The control unit typically processes the signal and compares it with a pre-determined threshold. Based on the result of the comparison it decides whether to supply a signal to activate the restraint system. In the course of a full-frontal impact the central sensor measures high decelerations which quickly lead to a signal exceeding the threshold, ensuring sufficiently early activation. However, this may not be so in the case of other types of frontal impact, such as oblique. Whilst a lower threshold may permit sufficiently early activation in response to an oblique impact it increases the risk of undesired activation in response to non-impact conditions such as travelling over rough surfaces. In order to distinguish between impact and non-impact conditions additional sensors (designated "second" in this file) are positioned closer to the front of the vehicle in order to determine when an impact occurs and their signals are used by the control unit to then adjust the threshold. The patent relates to the manner in which the threshold is adjusted.

Main request

2. During the written phase of the appeal procedure appellant II pursued its objection raised in opposition proceedings that the subject-matter of claim 1 as granted had been amended in such a way as to extend beyond the content of the application as filed (Article 100(c) EPC 1973). However, that objection was withdrawn during the oral proceedings on 19 February 2010 so that it remains to consider only inventive step of the subject-matter of this request.

3. The board and all parties are in agreement that the closest state of the art is disclosed by E1. There is further agreement that E1 discloses at least all features of present claim 1 except:

- wherein said threshold changing means comprises threshold change amount increasing means for increasing a change amount of said predetermined threshold with increase in a value based on the detection value of said second sensor means.

This feature has the effect of better tailoring the response of the system to the severity of the impact. The corresponding problem as defined by appellant I may be seen as optimising the timing of activation of the occupant safety system. E1 discloses that the threshold be changed in dependence on a signal received from the second sensor. The party as of right argues that since in accordance with E1 the signal from the second sensor may be a continuous one it is implicit that the degree of change of the threshold is similarly variable. However, that is not directly and unambiguously derivable from E1 since the variable signal from the second sensor may be associated with a series of equally sized changes in the value of the threshold.

4. D4 relates to an activation device for a side-impact protection system. It begins by explaining that whilst airbags were well known for use in frontal impacts the minimal crumple zone available in side impacts places high demands on the sensor and control unit to achieve satisfactory protection within the time available. It acknowledges earlier prior art for use in frontal impacts in which a first, central sensor is employed together with a second, more forwardly located sensor whose signal is used to lower the activation threshold. It states that the system could be used for side impact protection but that adaption to the more critical timing would result in a level of the threshold which is too low to avoid undesired activation. In accordance with D4 the signal from the side sensor is used to trigger integration of the signal from the central sensor, which integrated signal is then compared with a threshold value to trigger activation of the airbag. In one embodiment the threshold is reduced by an amount in dependence on the speed of deformation derived from the side sensor, see particularly column 5, lines 5 to 8 and claim 4.

4.1 As argued by appellant II the skilled person would be aware that the fundamental considerations pertaining to frontal and side impacts are essentially identical. Indeed, this is derivable from the acknowledgement in D4 of earlier state of the art relating to frontal impact. As regards timing of activation the conditions are more critical in the side impact because of a reduced crumple zone. The skilled person therefore would consider the teaching of D4 when seeking to improve the timing of activation of the system according to E1. He would particularly be drawn to the statement in D4 column 5, lines 5 to 8 that a higher speed of deformation leads to a greater reduction in the threshold. In applying that teaching to the system according to E1 he would arrive at the subject-matter of present claim 1 without inventive activity.

4.2 Appellant I argues that the problem of ensuring that an airbag is activated sufficiently early in the case of an oblique impact does not arise in D4. However, that problem has already been solved in E1 by the use of the signal from the second sensor as a basis for adjusting the threshold to reliably avoid undesired activation whilst nevertheless ensuring that sufficiently early activation during an impact. That same problem, albeit in the context of side impacts, has already been solved also in D4. However, the teaching of D4 is more complete as regards the manner in which the threshold is changed and it is that information which the skilled person would learn from D4 and apply to the system disclosed in E1. Whilst E1 and D4 do provide different types of second sensor, in both cases the signals generated by them are employed to create a speed signal.

5. On the basis of the foregoing the board finds that the subject-matter of present claim 1 does not involve an inventive step (Article 100(a) EPC 1973).

First auxiliary request

6. The subject-matter of claim 1 according to this request differs only in that the threshold is "lowered". E1 mentions that the threshold is changed but is silent as to the direction of change. However, it is implicit for the skilled person that the change would be to lower the threshold. As set out under point 1 above, the idea behind employing sensors at the front of the vehicle is to increase the sensitivity of the system in response to the certainty that an impact has occurred. Such an increase in sensitivity is achievable by changing the threshold only downwards. Moreover, not only is this feature known from D4, see column 4, lines 44 to 51, but also in the earlier state of the art relating to frontal impacts acknowledged in D4, see column 1, lines 41 to 44. The board therefore concludes that the amendment to claim 1 according to this request fails to establish an inventive step.

Second auxiliary request

7. Claim 1 according to this request contains in comparison with claim 1 as granted the additional feature that the value derived from the signal of the second sensor means and on which the change of the threshold is based is an integration of the signal over a predetermined time. In accordance with E1 the change in the threshold is dependent on a signal from the front sensor but the manner in which the acceleration signal provided by the sensor is processed is not disclosed. D4, on the other hand, teaches that the value derived from the second sensor and upon which the change in the threshold is based is the speed of deformation, see e.g. column 3, line 62 to column 4, line 4. The skilled person would know from his general knowledge that a corresponding speed value representative of the severity of the impact would be obtainable from an acceleration signal by integrating it over a predetermined time. Application to E1 of the teaching of D4 in the light of that general knowledge would result in integration of the signal provided by the second sensor means. It follows that the subject-matter of claim 1 also according to this request does not involve an inventive step.

Third auxiliary request

8. Before considering this request in detail the board considers it useful to briefly recap that it has found in respect of the first and second auxiliary requests that it is obvious to arrange the threshold changing means to integrate the acceleration signal obtained from the second sensor means to form a value as a basis for lowering the threshold. In comparison with those higher order requests the additional wording in claim 1 according to the present request essentially further specifies that the lowering of the threshold is achieved by "subtraction" of the integrated value from the threshold. Appellant I offered no argumentation in support of inventive step of this feature and in the board's view this method of lowering the threshold would readily occur to the skilled person. Indeed, in D2, which also relates to a system for activating an occupant restraint system, the lowering of the threshold is by a simple act of subtraction, see column 5, lines 20 to 25. The board therefore finds that also the subject-matter of claim 1 according to this request does not involve an inventive step.

Fourth auxiliary request

9. Claim 1 according to this request contains the additional feature of "threshold change amount decreasing means for decreasing the change amount of said predetermined threshold corresponding to an initial increase state of the operation value based on the detection value of said first sensor". It is unclear what is meant by the wording "initial increase state". In particular, whilst the term "increase" implies a comparison it is unclear what the basis for the comparison might be when the term "initial" implies that no earlier state can serve as a basis for the comparison. It is common in the event of difficulties in understanding the wording of a claim during opposition appeal proceedings to interpret the claim in the light of the description. Corresponding wording is found in paragraphs [0018], [0019] and [0064] in the latter two of which there is reference to avoiding over-sensitivity to accelerations sensed whilst travelling over rough roads. It would therefore appear that the aim is to avoid over-sensitising the system under certain conditions, indeed appellant I confirmed as much. However, the definition of the subject-matter of the claim, namely an apparatus to achieve that aim, remains obscure. Appellant I argues that the wording added to claim 1 according to this request is clear because it was in claim 9 as granted. The Enlarged Board of Appeal set out in decision G 9/91 (OJ EPO 1993, 408), see point 19, that "in the case of amendments of the claims or other parts of a patent during the course of opposition or appeal proceedings, such amendments are to be fully examined as to their compatibility with the requirements of the EPC". In the present case claim 1 has been rendered unclear as a result of the amendment. Moreover, without being able to understand what is the subject-matter of the claim the board finds itself unable to judge the presence of any inventive step. Under these circumstances the board has no option but to find the present request unallowable due to lack of clarity of claim 1.

10. Further objection arises from the presentation of an additional independent claim. In the claims as granted a single independent claim 1 was followed by inter alia dependent claims 9 and 10. In accordance with the present request, on the other hand, two independent claims 1 and 3 contain the features of granted claims 1, 9 and 1, 10 respectively. Since claim 10 as granted was dependent on inter alia claim 9 its subject-matter could have remained in a claim dependent on presently amended claim 1. The filing of independent claim 3 therefore is not necessitated by a ground for opposition and appellant I failed to provide any reasoning to the contrary. In accordance with established case law of the Boards the filing of an additional independent claim which is not necessitated by a ground for opposition is not admissible, see e.g. T 313/98, point 1.1 of the Reasons (not published in OJ EPO).

Fifth auxiliary request

11. Claim 1 has been amended according to this request essentially to specify that the predetermined threshold is stored "in a determination map". In the application as originally filed the determination map was first described in paragraph [0033], to which the appellant refers as the basis in the original disclosure. It was illustrated for various disclosed embodiments in the respective figures 4, 6A, 8A and 12 as a plot of the threshold in respect of V2 and V1 where V2 and V1 signify integration of the deceleration measured by the central sensor over periods of 10ms and 150ms respectively. The skilled person presented with the application as originally filed was therefore taught that the determination map is a storage of values of the threshold for a range of values of the acceleration measured over two particular and very different time periods. The determination map as in present claim 1, on the other hand, is wholly unspecified in respect of the time periods over which the integration is performed. As a result, the patent as amended according to this request teaches a more general case than the original, for which there was no basis in the application as originally filed and thereby extends the subject-matter (Article 123(2) EPC).

Sixth auxiliary request

12. Claim 1 in this request includes the same wording as was added to claim 1 according to the fourth auxiliary request and accordingly also is unclear in defining the subject-matter to be protected. Moreover, also as in accordance with the fourth auxiliary request, an independent claim 3 has been added. This request therefore results in the same objections as does the fourth auxiliary request.

On the basis of the forgoing the board finds that none of the requests can be accepted.