Saturday, 24 September 2011

T 1479/08 – Wrong Lane

Some time ago, I have dedicated a post to decision T 176/84, which had made some important remarks on which technical fields were to be taken into account when assessing whether an invention involved an inventive step.

The present decision gives an example of how this teaching is applied.

The Opposition Division had rejected the oppositions and one of the opponents had filed an appeal.

Claim 1 as granted concerned a lane-following system for facilitating steering of a vehicle by tracking a lane of a roadway. Some of the prior art cited by the opponent (documents E3 and E6) were not in the technical field of lane control. The opponent cited T 176/84 to support its view that the skilled person would nevertheless consult these documents. Will the Board follow this reasoning?

The Board first determined E1 to be the closest prior art. It then pursued:

[3.1] Starting out from E1 as the most relevant prior art, the system according to claim 1 specifies the operation of the controller as being to evaluate the “manner” […] in which detection of the presence of lane marking has failed and to hold control of steering inoperable for a predetermined time period in response to the evaluation result.

The characterizing features solve the technical problem of steering control being intermittently switched on and off due to intermittent detection of the lane marking […].

E1 in combination with E2

[3.2] For the sake of argument the board assumes that the skilled person, starting out from document E1, would find it obvious to apply the teaching of E2. E2 relates to a lane following system for assisting a driver steering a vehicle. The system detects a line marking by means of three light detectors detecting light reflected from the lane marking. A line marking is judged as being present only after it has been continuously detected for a predetermined period, which for a given vehicle speed corresponds to a set driving distance. When lane marking is detected over more than this set distance, steering control is resumed […]. The predetermined period is applied in response to each change of detection of the lane marking from being absent to being present.

Thus, starting out from E1 as the closest prior art, the person skilled in the art would be led by E2 to resume steering control with a delay each time the detection of the line marking changes from being absent to being present. The skilled person would however not be led by E2 to evaluate, by considering the history of lane marking detection, the manner of failure of detection of the presence of the lane marking as a criterion for deciding on whether or not steering control should be resumed with a delay.

Thus, the system according to claim 1 is not rendered obvious to the skilled person having regard to the combination of E1 and E2.

E3 and E6: Closely related technical fields?

[3.3.1] With reference to T 176/84 the [opponent] argued that the skilled person would also consider prior art in the adjacent technical fields of E3 and E6.

At point [5.3.1] of the reasons of T 176/84 it is stated:
“While it is indeed perfectly reasonable to expect a person skilled in the art if need be, i.e. in the absence of useful suggestions in the relevant field as to how a given problem might be solved, to look for suitable parallels in neighbouring fields, the question of what is a neighbouring field is one of fact and the solution depends, in the opinion of the Board, on whether the fields are so closely related that the person skilled in the art seeking a solution to a given problem would take into account developments in the neighbouring field.”
Thus, the board has to decide whether the skilled person would take into account E3 and E6 when seeking a solution for the problem as stated at point [3.1] above.


[3.3.2] E6 is an extract from a technical book relating to target tracking by means of radar. Chapter 1.3.4 relates to the initiation and confirmation of a tentative track in airborne radar systems. It is suggested that a tentative new track is only confirmed when the associated object has been observed M times within N observation scans. Thus, E6 relates to the specific problem of track confirmation in the field of radar systems, which is somewhat remote to the field of steering control. 

Moreover, the issue addressed in E6 is deciding when a tentatively observed track can be confirmed as a real track. In the contested patent confirmation of the presence or absence of a lane marking is not an issue since the lane marking has already been confirmed as being either present or absent. 

The board is therefore of the view that E6 would not be considered by the skilled person since it relates to a different technical field and moreover to a different issue.


[3.3.3] E3 relates to a system for automatically switching the lights of a vehicle on and off depending on the ambient light level. When the ambient light level rapidly changes the system controls the lights so as to remain switched on for an additional delay CFE each time the level changes from dark to light. Thus, E3 is in the technical field of lighting control for a vehicle, which is different from steering control.

Although the methodology in E3 for judging when the light should be kept on or off dependent on the ambient light level appears to be similar to that for switching on and off the steering control in the patent (compare figure 2 of E3 with figure 4 of the patent specification) …

Fig. 2 of E3

Fig. 4 of the opposed patent

… the board is not convinced that the skilled person would, without the benefit of hindsight, have been led by E3 to the system as claimed in claim 1 of the patent. In the board’s view the skilled person would first have to recognize that the methodology in E3 could be generalized for the purpose of avoiding control hunting in a field other than lighting control. Subsequently, the skilled person would be required to identify the presence of the lane marking in the lane control system as the appropriate input parameter the evaluation of which could reasonably serve to decide whether or not the controller should be held inoperable for a delay time in response to the evaluation result. The board is of the view that the skilled person would not have carried out these steps without the benefit of hindsight. Thus, the skilled person would not be led by E3, either alone or in combination with E1, to the system as claimed in claim 1 of the patent.

Should you wish to download the whole decision, just click here.

The file wrapper can be found here.