T 0440/18 (Light source control /HELVAR) 05-10-2022

1. The patent concerns the control of a lighting device comprising two light sources such as LEDs. The patent aims to provide a simple and versatile control of the lighting device so as to adjust both brightness and colour temperature in response to a single input control signal (description, [0004] and [0007]).

Main request, insufficiency of disclosure

2. Claim 1 defines that the controlled change of characteristics of light comprises an adjustment of the ratio between the light intensities of two light sources, and an adjustment of the combined light intensity of the two light sources. In simpler terms, this control is an adjustment of colour temperature and brightness.

3. The proprietor argued that claim 1 simply required the apparatus to be able to change both the brightness and the colour temperature within a single control cycle. The patent specification disclosed various examples of such an apparatus. It was, therefore, disclosed in a manner sufficiently clear and complete to be implemented by the skilled person in accordance with the requirements of Article 100(b) EPC.

4. Contrary to the proprietor's arguments, though, an adjustment of brightness and colour temperature is not synonymous with simply a change of these variables. While it is clear that an adjustment of these variables includes that they are changed, an adjustment defines more than that. It defines that the change is directed towards achieving a certain objective. This even follows from the explanation of the term "adjust" in the dictionary extracts submitted by the proprietor as "to alter sth by a small amount so that it will fit properly or be right for use" (see Oxford Advanced Learner's Dictionary of Contemporary English, Fifth edition) or "to change something slightly, especially to make it more correct, effective or suitable" (Cambridge Advanced Learner's Dictionary, edition unknown). According to these definitions, an adjustment is not to be equated with merely changing a variable.

5. Claim 1 therefore does not merely define an apparatus in which brightness and colour temperature can be arbitrarily changed within a single control cycle. Rather, the claim defines an apparatus that allows any kind of adjustment of both brightness and colour temperature, including an apparatus where both brightness and colour temperature can be adjusted within a single control cycle to settings provided by the user.

6. However, an apparatus capable of doing so is not disclosed in the patent. The patent only discloses examples in which a combination of brightness and colour temperature can be adjusted within a single control cycle to a restricted extent, namely such that adjusting one of brightness or colour temperature to a setting desired by the user limits the extent of adjustment of the other (see Figures 4a and 4b which shows the relationship between the input control signal and the change in the combined light intensity and the colour temperature; the colour temperature is changed only after the combined light intensity has reached a minimum or maximum level).

7. The patent therefore does not provide the skilled person with sufficient information for carrying out the invention in claim 1 over the whole scope of the claim.

8. Therefore, the ground for opposition pursuant to Article 100(b) EPC prejudices the maintenance of the patent on the basis of the main request.

Auxiliary request, admission and consideration

9. The auxiliary request was submitted after the summons to oral proceedings by the Board. Its admission is subject to the Board's discretion.

10. The Board considers the auxiliary request to be a reaction to the Board's communication, which raised slightly different arguments on the issue of lack of sufficiency of disclosure than what had previously been discussed.

11. Although the auxiliary request could have been submitted earlier than two months before the oral proceedings, the Board considers that the timing is not a critical issue for admission in this case. No new issues were introduced by the auxiliary request, so that there was enough time for the Board and the opponent to prepare the case for oral proceedings.

12. Moreover, claim 1 of this request is based on claim 6 of the granted patent, against which the opponent had an opportunity to present their case in the notice of opposition.

13. The amendments can furthermore be seen to prima facie address, and overcome, the issues identified in the main request by further specifying the adjustments defined in the claim.

14. All things considered, there are exceptional circumstances and cogent reasons which justify the submission of an amended set of claims after the summons to oral proceedings. Pursuant to Article 13(2) RPBA 2020, the auxiliary request is therefore to be taken into consideration.

Auxiliary request, sufficiency of disclosure

15. The added features further define the adjustments that the device is configured to carry out, more precisely: the time sequence of the adjustments to the brightness and to the colour temperature are specified, as is the transition point from a change of the brightness to a change of the colour temperature.

16. Due to these features, the apparatus is defined as being able to adjust brightness and colour temperature only to a limited extent. The user can adjust, within a control cycle, either the brightness by terminating the control signal before the transition point is reached, or the colour temperature by terminating the control signal after the transition point is exceeded.

17. An apparatus capable of performing such an adaptation is disclosed, for example, in Figure 4a of the patent specification.

18. The opponent argued that the apparatus in claim 1 of the first auxiliary request was still defined as able to adjust both brightness and colour temperature to a user-desired setting within one control cycle. Therefore, the apparatus was insufficiently disclosed for the same reasons as for the main request. The added features did not further define the term "adjustment", but rather introduced the possibility that only the combined light intensity was adjusted (the first alternative before the "or" in claim 1). This was even incompatible with the prior definition that both were adjusted.

19. The Board does not agree. For a device to be operable to either adjust the brightness to a user defined level, or the brightness to a system defined level and then the colour temperature to a user defined level, depending on the length of the command, it needs to be configured to carry out both adjustments. Therefore, rather than being incompatible with the features added to the claim, the definition of the device as configured to adjust both quantities is seen as necessary for the system to be operated as defined.

Thus, claim 1 of the first auxiliary request defines an adjustment of both brightness and colour temperature such as disclosed in Figure 4a of the patent.

20. In conclusion, the apparatus defined in claim 1 of the auxiliary request is disclosed in the patent in a manner sufficiently clear and complete for it to be carried out by the skilled person.

Auxiliary request, inventive step

21. D2 discloses a controllable device for operating LED light sources. The device (fig. 1) includes a push button (Taster, Tst.) as an input portion for entering a control input signal. The device is configured to receive the signal from the push button at a port K and to evaluate the duration of pressing the push button.

22. Accordingly, a short operation of the push button is recognised as a command for switching the light on or off. The skilled person would have understood that "short" in this context means that the duration is less than some predetermined time. The device is further configured to detect the time when the push button is operated "longer" and to evaluate the time as a setting for brightness, colour or colour temperature (D2, page 11, lines 11 to 20). The skilled person would have understood "longer" as meaning that the duration is longer than the predetermined time.

23. D2 does not explicitly describe that the device is for operating a first light source of a first colour and a second light source of a second colour. However, the skilled person would have implicitly inferred from the indication that the device is for controlling LED light sources to adjust the luminance or colour temperature that at least two light sources of different colour temperatures are present. The skilled person would have understood further that the light sources may be controlled such that the colour temperature of the emitted light can be adjusted by the duration of actuation of the push button.

24. The skilled reader would further have inferred that the disclosed adjustment of the total light intensity implied controlling the partial intensities of the light sources such that they stay in a constant relation to each other, and that the disclosed adjustment of the colour temperature implied changing the ratio of the intensities of different colours.

25. Thus, the apparatus of claim 1 differs from the device disclosed in D2 in that, in response to a single input control signal, both the ratio between the light intensities of the light sources and the combined light intensity of the light sources are adjusted, wherein the adjustment of the combined light intensity occurs first and the control portion is configured to continue the adjustment of combined light intensity until termination of the input control signal or until reaching a maximum or a minimum combined light intensity, and the adjustment of the ratio between the light intensities thereafter.

26. Even though D2 discloses that, in addition to brightness, "also" colour temperature can be adjusted, D2 fails to describe a concrete implementation of adjusting both brightness or colour temperature. Thus, the effect of the distinguishing features resides in providing an implementation of a control for adjusting both brightness and colour temperature.

27. The problem to be solved is to provide an implementation for controlling both brightness and colour temperature of the lighting device.

28. The opponent argued that D2 disclosed all the elements of adjusting brightness or colour temperature of a light source. Therefore, no technical problem was apparently solved by the claimed apparatus.

29. The Board does not agree. Providing a concrete implementation when starting from a general teaching in the prior art is a technical problem.

30. Starting from D2, it would not have been obvious to consider a solution employing a single control signal sequentially adjusting brightness and colour temperature, by first adjusting the brightness and, if the user would not have terminated the control cycle at a desired level of the brightness, continue with adjusting the colour temperature.

31. There is also no other prior art that would render the particular implementation in claim 1 of the first auxiliary request obvious.

32. For these reasons, the apparatus of claim 1 of the first auxiliary request involves an inventive step having regard to D2.