Black body locus dimming depending on sensed ambient light conditions

Abstract

A lighting system comprising a light source, a user interface, a sensor, and a controller. The lighting system is configured to emit light output having a luminous flux and a correlated color temperature (CCT). The user interface is configured to provide a user signal, representing a lighting parameter for a desired luminous flux and / or a desired CCT of the light output, having an input signal range from a lower to an upper limit. The sensor is configured to sense intensity and / or sense CCT of ambient light and further configured to provide a sensor signal representing the sensed intensity and / or the sensed CCT of the ambient light. The controller is configured to receive the sensor signal and the user signal and to control, based on these signals, the luminous flux and / or the CCT of the light output in a respective range from a lower to an upper limit.

Description

[0001] Black body locus dimming depending on sensed ambient light conditions

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to lighting systems. More specifically, the present invention is related to a lighting system in which luminous flux and / or correlated color temperature of light is controlled.

[0004] BACKGROUND OF THE INVENTION

[0005] The original bulb lamps powered by electricity were of the type having metal wire filaments enclosed within more or evacuated glass bulbs. This type of bulb lamps was the ubiquitous choice of light source for more than a century until the introduction of light sources utilizing light emitting diodes (LEDs). Light sources based on LEDs have now replaced the light bulb as a source of light in homes and in many other locations. Initially, mainly due to the inherent structural characteristics of LEDs, the early LED light sources (i.e. LED lamps) did not resemble the earlier light bulbs and in many cases were considered as aesthetically inferior to a light bulb of the earlier type. Thus, for aesthetic reasons, a desire for light sources having the look of the traditional bulb shaped filament lamp came back when it was found that this was technically feasible to make light sources using LED filaments.

[0006] However, there still remain various aspects of such light sources using LEDs that need attention. For example, there is still a need to improve the appearance and user viewing experience of light sources using LEDs. Black body locus (BBL) dimming, i.e. a decrease in light source correlated color temperature (CCT) correlates with a decrease in light source intensity, is used in many lighting devices, especially in LED based lamps and luminaires. Nevertheless, there remains a need for improving the appearance of light sources such that the user experience of a light source is independent of the ambient light conditions.

[0007] SUMMARY OF THE INVENTION

[0008] It is of interest to provide a light source device that is capable of overcoming the drawbacks of prior art devices. This and other objects are achieved in a first aspect by providing a light source device having the features of the appended independent claim. Preferred embodiments are defined in the appended dependent claims.

[0009] Hence, according to the present invention there is provided a lighting system comprising a light source, a user interface, a sensor, and a controller.

[0010] The light source is configured to emit a light output, the light output having a luminous flux and a correlated color temperature (CCT). Preferably, the light source comprises an LED light source. More preferably, the light source comprises a plurality of LED light sources of distinct colors.

[0011] The user interface is configured to provide a user signal. The user signal is a physical entity and may for example comprise a voltage, a current, an impedance value, or the like.

[0012] The user signal represents a lighting parameter. The lighting parameter is a desired luminous flux of the light output and / or a desired CCT of the light output.

[0013] The user signal has a user signal range from a user signal lower limit to a user signal upper limit. The user signal lower and upper limits are physical entities and may for example comprise a voltage, a current, an impedance value, or the like.

[0014] The user interface may comprise at least one of a slider, a knob, a push button, a touch button, any form of touch display, digital interface or the like.

[0015] The sensor is configured to sense intensity and / or sense CCT of ambient light. The sensor is further configured to provide a sensor signal. The sensor signal may for example comprise a voltage, a current, an impedance value, or the like.

[0016] The sensor signal represents the sensed intensity of the ambient light and / or the sensed CCT of the ambient light.

[0017] The sensor may for example comprise an optical sensor, such as a photoelectric sensor. The sensor may be configured to measure the intensity (for example the number of photons) and / or the spectral distribution of ambient light.

[0018] The controller is configured to receive, from the sensor, the sensor signal. The controller is further configured to receive, from the user interface, the user signal.

[0019] The controller is configured to control, based on the user signal and the sensor signal, the luminous flux of the light output. The luminous flux being in a luminous flux range from a lower luminous flux limit to an upper luminous flux limit. Additionally or alternatively, the controller is configured to control, based on the user signal and the sensor signal, the CCT of the light output. The CCT being in a CCT range from a lower CCT limit to an upper CCT limit.

[0020] The controller is further configured to adjust the luminous flux range dependent on the sensor signal, and / or to adjust the CCT range dependent on the sensor signal.

[0021] The user interface, the sensor, the light source, and the controller may communicate with each other via any form of wired or wireless communications means.

[0022] The size of the luminous flux range, wherein the size of the luminous flux range is defined as the difference between the upper luminous flux limit and the lower luminous flux limit, may be at least 300 Im. The lower luminous flux limit may be at least 300 Im. The upper luminous flux limit may be at least 600 Im.

[0023] The size of the CCT range, wherein the size of the CCT range is defined as the difference between the upper CCT limit and the lower CCT limit, may be at least 500 K or at least 1000 K or at least 1500 K. The lower CCT limit may be at least 1500 K. The upper CCT limit may be at least 3000 K.

[0024] In other words, the range of dimming for such a lighting system is dependent on the ambient lighting conditions, as sensed by the sensor and communicated to the controller via the sensor signal. The ambient light conditions will, for example, naturally vary depending on the time of day, as well as on the current weather conditions, and other factors. The input signal range may typically be fixed, while the luminous flux range and / or CCT range may according to the invention be changed depending on ambient light conditions. From a user / viewer perspective, what is experienced as for example a dark / bright or warm / cold light source will depend on the ambient light conditions. Thus by changing the luminous flux range and / or CCT range depending on ambient light conditions, the user experience can be made independent of ambient light conditions. Additionally, since the luminous flux range and / or the CCT range is mapped onto the input signal range, the resolution of the user interface can effectively be altered. For example in darker ambient light conditions, a smaller change in the input signal may result in a greater change in luminous flux than the corresponding change of input signal would at brighter ambient light conditions.

[0025] In some embodiments, the controller is configured to set the size of the luminous flux range to be constant, wherein the size of the luminous flux range is defined as the difference between the upper luminous flux limit and the lower luminous flux limit. For the sensor signal that indicates a relatively high intensity of the ambient light, the controller sets the upper luminous flux limit and the lower luminous flux limit to a relatively high luminous flux respectively. For the sensor signal that indicates a relatively low intensity (210) of the ambient light, the sensor sets the upper luminous flux limit and the lower luminous flux limit to a relatively low luminous flux respectively.

[0026] The expression set should throughout the application be understood as that the value being referred to as set is capable of being changed, in contrast to being a constant value. In other words, expressions such as “set the luminous flux” could also be written, for example, as “change / vary / increase / decrease the luminous flux”. The same is true for other expressions of similar type referring to other parameters than luminous flux.

[0027] The expressions relatively high and relatively low, respectively, should here and throughout the application be understood as high and low compared to each other, and not as high and low in any absolute sense. For example, the luminous flux is said to go from a relatively low to a relatively high luminous flux as the luminous flux increases. The luminous flux is said to go from a relatively high to a relatively low luminous flux as the luminous flux decreases. In other words, relatively high may mean an increase, and relatively low may mean a decrease. The same applies with regard to a relatively high / low CCT, respectively, and any other similar instances. A relatively low CCT may be e.g. in a range from 1500 to 2500K. A relatively high CCT may be e.g. in a range from 3500 to 6500K. A relatively low luminous flux may be e.g. in a range from 30 to 300 Im. A relatively high luminous flux may be e.g. in a range from 700 to 2000 Im.

[0028] In some embodiments, the controller is configured to set the size of the CCT range to be constant, wherein the size of the CCT range is defined as the difference between the upper luminous flux limit and the lower luminous flux limit. For the sensor signal indicating a relatively high CCT of the ambient light, the controller sets the upper CCT limit and the lower CCT limit to a relatively high CCT respectively. For the sensor signal indicating a relatively low CCT of the ambient light, the controller sets the upper CCT limit and the lower CCT limit to a relatively low CCT respectively.

[0029] In other words, either one of, or both of, the size of the luminous flux range and the size of the CCT range may remain constant, while the respective lower and upper limits may be shifted depending on the sensor signal describing the ambient light conditions. For example, under dimmer ambient light conditions the limits may be decreased, while under brighter conditions the limits may be increased. Such control over the light output is desired in order to improve the appearance and user viewing experience.

[0030] In some embodiments, the controller is configured to set the size of the luminous flux range by setting the lower luminous flux limit and maintaining the upper luminous flux limit constant. Also or alternatively, set the size of the CCT range by setting the lower CCT limit and maintaining the upper CCT limit constant. The size of the luminous flux range and / or the size of the CCT range is thus controlled by changing the respective lower limits. In another embodiment, the controller is configured to set the size of the luminous flux range by setting the upper luminous flux limit and maintaining the lower luminous flux limit constant. Also or alternatively, the controller is configured to set the size of the CCT range by setting the upper CCT limit and maintaining the lower CCT limit constant. The size of the luminous flux range and / or the size of the CCT range is thus controlled by changing the respective upper limits. An advantage of such embodiments is that the size of the luminous flux range and the size of the CCT range is controlled to be different depending on the ambient light conditions.

[0031] In some embodiments, the controller is configured to set the size of the luminous flux range by setting the upper luminous flux limit and the lower luminous flux limit, also or alternatively, the controller is configured to set the size of the CCT range by setting the upper CCT limit and the lower CCT limit. The size of the luminous flux range and / or the size of the CCT range is thus controlled by changing both the respective upper limits and the respective lower limits. In this way, the change may be more advanced e.g. better suited to certain conditions and various applications, such that the appearance and user viewing experience of the light output is improved.

[0032] In some embodiments, the controller is configured to, for the sensor signal indicating a relatively high intensity of the ambient light, set the size of the luminous flux range to a relatively large size of the luminous flux range. In some embodiments, the controller is configured to, for the sensor signal indicating a relatively low intensity (210) of the ambient light, set the size of the luminous flux range to a relatively small size of the luminous flux range. In some embodiments, the controller is configured to, for the sensor signal indicating a relatively high CCT of the ambient light, set the size of the CCT range to a relatively large size of the CCT range. In some embodiments, the controller is configured to, for the sensor signal indicating a relatively low CCT of the ambient light, set the size of the CCT range to a relatively small size of the CCT range. In other words, the size of the luminous flux range and the size of the CCT range may increase / decrease with respectively increasing / decreasing luminous flux and CCT of the ambient light. Such correlation is desired to improve the appearance and user viewing experience.

[0033] In some embodiments, the controller is configured to set the size of the luminous flux range and the size of the CCT range wherein a ratio between the size of the luminous flux range and the size of the CCT range is varied based on the sensor signal. For the sensor signal indicating a relatively high intensity and / or a relatively high CCT of the ambient light, the size of the luminous flux range and / or the size of the CCT range may be set such that the ratio between the size of the luminous flux range and the size of the CCT range is a relatively high value. For the sensor signal indicating a relatively low intensity and / or a relatively low CCT of the ambient light, the size of the luminous flux range and / or the size of the CCT range may be set such that the ratio between the size of the luminous flux range and the size of the CCT range is a relatively low value.

[0034] In other words, the variation of the ratios describes black body locus / line, BBL, dimming. Accordingly, it is preferable that the CCT and the luminous flux of the light source can be controlled at the same time, and the ratio between both ranges may change depending on the ambient light conditions. Such BBL dimming is desired to improve the appearance and user viewing experience.

[0035] In some embodiments the controller is configured to determine that the sensor signal indicates an increase in intensity of the ambient light from a first intensity level to a second intensity level, over a specified time period, which is at least 50% higher than the first intensity level. As a consequence of said determination, the controller may increase the size of the luminous flux range from a first size of the luminous flux range to a second size of the luminous flux range. The second size of the luminous flux range may be at least 50% larger than the first size of the luminous flux range. The controller may be configured to determine that the sensor signal indicates a decrease in intensity from the first intensity level to the second intensity level, over a specified time period, which is at least 50% lower, or at least 70% lower, than the first intensity level. As a consequence of said determination, the controller may decrease the size of the luminous flux range from a first size of the luminous flux range to a second size of the luminous flux range. The second size of the luminous flux range may be at least 50% lower, or at least 70% lower, than the first size of the luminous flux range. In some embodiments said increase of the size of the luminous flux range may be less than the determined increase in intensity indicated by the sensor signal. In other embodiments said increase of the size of the luminous flux range may be more than the determined increase in intensity indicated by the sensor signal. Also or alternatively, said decrease of the size of the luminous flux range may be less than the determined decrease in intensity indicated by the sensor signal. In other embodiments said decrease of the size of the luminous flux range may be more than the determined decrease in intensity indicated by the sensor signal.

[0036] In some embodiments said increase of the size of the CCT range may be less than the determined increase in CCT indicated by the sensor signal. In other embodiments said increase of the size of the CCT range may be more than the determined increase in CCT indicated by the sensor signal. Also or alternatively, said decrease of the size of CCT range may be less than the determined decrease in CCT indicated by the sensor signal. In other embodiments said decrease of the size of the CCT range may be more than the determined decrease in CCT indicated by the sensor signal.

[0037] The controller may be configured to determine that the sensor signal indicates an increase in CCT from a first CCT value to a second CCT value, over a specified time period, which is at least 500K higher or at least lOOOK higher than the first CCT value. The specified time period may for example be 1 minute, 10 minutes, or 1 hour. As a consequence of said determination, the controller may increase the size of the CCT range from a first size of the CCT range to a second size of the CCT range. The second size of the CCT range may be at least 500K higher or at least lOOOK higher than the first size of the CCT range. The controller may be configured to determine that the sensor signal indicates a decrease in CCT from a first CCT value to a second CCT value, over a specified time period, which is at least 500K lower than the first CCT value. As a consequence of said determination, the controller may decrease the size of the CCT range from a first size of the CCT range to a second size of the CCT range. The second size of the CCT may be at least 500K lower than the first size of the CCT range. In some embodiments said increase / decrease of the size of the CCT range may be less than the determined increase / decrease in CCT indicated by the sensor signal. In other embodiments said increase / decrease of the size of the CCT range may be more than the determined increase / decrease in CCT indicated by the sensor signal.

[0038] Typically there is a large variation in CCT of the ambient light during the day, while the desired variation of the CCT of the artificial light is more limited. For example, the change in CCT of the ambient light during day may be e.g. from <2000K to >6000K i.e. a difference of 4000K or more, while in a room one would like to change the CCT a smaller amount, e.g. from 2000K to 3500K i.e. a difference of 1500K.

[0039] In some embodiments, the light source comprises a plurality of LEDs. The plurality of LEDs may comprise a cool white LED and a warm white LED. The plurality of LEDs may comprise a red LED, a blue LED and a green LED. The plurality of LEDs may comprise a white LED, a red LED, a blue LED and a green LED. The plurality of LEDs may comprise a cool white LED, a warm white LED a blue LED and a green LED.

[0040] In a further aspect, the lighting system may comprise at least one luminaire. The at least one luminaire may house the light source. The luminaire may further comprise a connector mechanically and electrically connected to a socket of the luminaire. Such a luminaire provides the effects and advantages as summarized above.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention where:

[0043] Fig. la schematically illustrates a lighting system ,

[0044] Fig. lb schematically illustrates a user interface for the lighting system,

[0045] Fig. 2a graphically illustrates a relationship of the light output,

[0046] Fig. 2b graphically illustrates a relationship of the light output, Fig. 2c graphically illustrates a relationship of the light output, Fig. 2d graphically illustrates a relationship of the light output, Fig. 3 schematically illustrates a luminaire.

[0047] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] As illustrated in figure la, an embodiment of a lighting system 100 comprises a light source 101, a user interface 104, a sensor 102, and a controller 103. The light source 101 is configured to emit light output 150, the light output 150 having a luminous flux and a correlated color temperature (CCT). Preferably the light source 101 comprises an LED light source. More preferably the light source comprises a plurality of LED light sources of distinct colors. The sensor 102 is configured to sense intensity and / or sense CCT of ambient light 140. The sensor is further configured to provide a sensor signal. The sensor signal is a physical entity and may for example comprise a voltage, a current, an impedance value, or the like. The sensor signal represents the sensed intensity of the ambient light 140 and / or the sensed CCT of the ambient light 140. The sensor may for example comprise a photoelectric sensor.

[0049] The user interface 104 is configured to provide a user signal. The user signal is a physical entity and may for example comprise a voltage, a current, an impedance value, or the like. The user signal represents a lighting parameter. The lighting parameter is a desired luminous flux of the light output 150 and / or a desired CCT of the light output 150.

[0050] As illustrated in figure lb, the user interface 104 comprises a means of controlling 105 the user signal. In the embodiment of figure lb, the means of controlling 105 the user signal comprises a rotatable knob. By interacting with the means of controlling 105 the user signal, a user can choose the user signal within an input signal range 124. The input signal range 124 comprises a plurality of user signal values 130 ranging from a user signal lower limit 120 to a user signal upper limit 122. The plurality of user signal values 130 may comprise either a discrete set of values or a continuous range of values. The user signal lower 120, the user signal upper limit 122, the user signal, and the plurality of signal values 130 are physical entities and may for example comprise a voltage, a current, an impedance value, or the like. The user interface may for example comprise a slider, a knob, a push button, a touch button, a touch display, a digital interface, or the like.

[0051] The controller 103 is configured to receive, from the sensor 102, the sensor signal. The controller 103 is configured to receive, from the user interface 104, the user signal. The controller 103 is configured to control, based on the user signal and the sensor signal, the luminous flux of the light output 150. The luminous flux being in a luminous flux range from a lower luminous flux limit 211, 221 to an upper luminous flux limit 212, 222. The controller 103 is also or alternatively configured to control the CCT of the light output 150. The CCT being in a CCT range from a lower CCT limit 211’, 221’ to an upper CCT limit 212’, 222’.

[0052] In some embodiments, the controller sets, based on the sensor signal, the lower luminous flux limit 211, 221 and / or the upper luminous flux limit 212, 222. Also or alternatively, the controller sets, based on the sensor signal, the lower CCT limit 211’, 221’ and / or the upper CCT limit 212’, 222’. The controller may further, based on the user signal, set the luminous flux of the light output 150 within the luminous flux range. Also or alternatively, the controller may, based on the user signal, set the CCT of the light output 150 within the CCT range.

[0053] In other words, the input signal range 124 is mapped onto the luminous flux range such that the user signal lower limit 120 represents the lower luminous flux limit 211, 221 and the user signal upper limit 122 represents the upper luminous flux limit 212, 222. Also or alternatively, the input signal range 124 is mapped onto the CCT range such that the user signal lower limit 120 represents the lower CCT limit 211’, 221’ and the user signal upper limit 122 represents the upper CCT limit 212’, 222’. In this way, the input signal range 124 represents either or both of the luminous flux range and the CCT range.

[0054] Further, the controller 103 is configured to adjust the luminous flux range dependent on the sensor signal. Also or alternatively, the controller 103 is configured to adjust the CCT range dependent on the sensor signal.

[0055] The size of the luminous flux range, wherein the size of the luminous flux range 213, 223 is defined as the difference between the upper luminous flux limit 212, 222 and the lower luminous flux limit 211, 221, may be 300 Im. The lower luminous flux limit 211, 221 may be at least 300 Im. The upper luminous flux limit 212, 222 may be at least 300 Im. The size of the CCT range, wherein the size of the CCT range 213’, 223 ’is defined as the difference between the upper CCT limit 212’, 222’ and the lower CCT limit 211’, 221’, may be 500 K. The lower CCT limit 211’, 221’ may be at least 500 K. The upper CCT limit 212’, 222’ may be at least 500 K.

[0056] As illustrated in figure 2a, in some embodiments the controller 103 is configured to set the size of the luminous flux range 213, 223 to be constant. In other words, the size of the luminous flux range 223 at relatively high intensity 220 of ambient light 140 is the same as the size of the luminous flux range 213 at relatively low intensity 210 of ambient light 140. For the sensor signal that indicates a relatively high intensity 220 of the ambient light 140, the controller sets the upper luminous flux limit 222 and the lower luminous flux limit 221 to a relatively high luminous flux respectively. For the sensor signal that indicates a relatively low intensity 210 of the ambient light 140, the sensor sets the upper luminous flux limit 212 and the lower luminous flux limit 211 to a relatively low luminous flux respectively.

[0057] Similarly, in some embodiments the controller 103 is configured to set the size of the CCT range 213’, 223’ to be constant. In other words, the size of the CCT range 223’ at relatively high CCT 220’ of ambient light 140 is the same as the size of the CCT range 213’ at relatively low CCT 210’ of ambient light 140. For the sensor signal that indicates a relatively high CCT 220’ of the ambient light 140, the controller sets the upper CCT limit 222’ and the lower CCT limit 221’ to a relatively high CCT 220’ respectively. For the sensor signal that indicates a relatively low CCT 210’ of the ambient light 140, the sensor sets the upper CCT limit 212’ and the lower CCT limit 211’ to a relatively low CCT 210’ respectively.

[0058] As illustrated in figure 2b, in some embodiments the controller 103 is configured to set the size of the luminous flux range 213, 223 by setting the lower luminous flux limit 211, 221 and maintaining the upper luminous flux limit 212, 222 constant. In other words, the upper luminous flux limit 222 for a relatively high intensity 220 of ambient light 140 will be the same as the upper luminous flux limit 212 for a relatively low intensity 210 of the ambient light 140. The lower luminous flux limit 221 for a relatively high intensity 220 of the ambient light 140 may differ from the lower luminous flux limit 211 for a relatively low intensity 210 of the ambient light 140.

[0059] Similarly, in some embodiments the controller 103 is configured to set the size of the CCT range 213’, 223’ by setting the lower CCT limit 211’, 221’ and maintaining the upper CCT limit 212’, 222’ constant. In other words, the upper CCT limit 222’ for a relatively high CCT 220’ of the ambient light 140 will be the same as the upper CCT limit 212’ for a relatively low CCT 210’ of the ambient light 140. The lower CCT limit 221’ for a relatively high CCT 220’ of the ambient light 140 may differ from the lower CCT limit 222’ for a relatively low CCT 210’ of the ambient light 140.

[0060] As illustrated in figure 2c, in some embodiments the controller 103 is configured to set the size of the luminous flux range 213, 223 by setting the upper luminous flux limit 212, 222 and maintaining the lower luminous flux limit 211, 221 constant. In other words, the lower luminous flux limit 221 for a relatively high intensity 220 of the ambient light 140 will be the same as the lower luminous flux limit 211 for a relatively low intensity 210 of the ambient light 140. The upper luminous flux limit 222 for a relatively high intensity 220 of the ambient light 140 may differ from the upper luminous flux limit 212 for a relatively low intensity 210 of the ambient light 140.

[0061] Similarly, in some embodiments the controller 103 is configured to set the size of the CCT range 213’, 223’ by setting the upper CCT limit 212’, 222’ and maintaining the lower CCT limit 211’, 221’ constant. In other words, the lower CCT limit 221’ for a relatively high CCT 220’ of the ambient light 140 will be the same as the lower CCT limit 211’ for a relatively low CCT 210’ of the ambient light 140. The upper CCT limit 222’ for a relatively high CCT 220’ of the ambient light 140 may differ from the upper CCT limit 212’ for a relatively low CCT 210’ of the ambient light 140.

[0062] In some embodiments, the controller 103 is configured to set the size of the luminous flux range 213, 223 by setting both the upper luminous flux limit 212, 222 and the lower luminous flux limit 211,221. Also or alternatively, the controller 103 is configured to set the size of the CCT range 213’, 223’ by setting both the upper CCT limit 212’, 222’ and the lower CCT limit 211’, 221’.

[0063] As illustrated in figure 2d, in some embodiments the controller 103 is configured to, at relatively high intensity 220 of the ambient light 140, set the size of the luminous flux range 223 to a relatively large size of the luminous flux range 223. The controller 103 may further be configured to, at relatively low intensity 210 of the ambient light 140, set the size of the luminous flux range 213 to a relatively small size of the luminous flux range 213.

[0064] Similarly, in some embodiments the controller 103 is configured to, at relatively high CCT 220’ of the ambient light 140, set the size of the CCT range 223’ to a relatively large size of the CCT range 223’. The controller 103 may further be configured to, at relatively low CCT 210’ of the ambient light 140, set the size of the CCT range 213’ to a relatively small size of the CCT range 213’.

[0065] In some embodiments, the controller 103 is configured to set the size of the luminous flux range 213, 223 and the size of the CCT range 213’, 223’ such that a ratio between the size of the luminous flux range 213, 223 and the size of the CCT range 213’, 223’ may be varied. The ratio may be varied based on the sensor signal. In some embodiments, the ratio is proportional to the size of the luminous flux range 213, 223 divided by the size of the CCT range 213’, 223’. In other embodiments, the ratio is proportional to the size of the CCT range 213’, 223’ divided by the size of the luminous flux range 213, 223.

[0066] In further embodiments, the controller 103 is configured to, at relatively high intensity 220 of the ambient light 140 and / or relatively high CCT 220’ of the ambient light 140, set the size of the luminous flux range 213, 223 and / or the size of the CCT range 213’, 223’ such that the ratio is a relatively high value. At relatively low intensity 210 of the ambient light 140 and / or relatively low CCT 210’ of the ambient light 140, the controller 103 is configured to set the size of the luminous flux range 213, 223 and / or the size of the CCT range 213’, 223’ such that the ratio is a relatively low value. In some embodiments, the controller 103 is configured to determine that the sensor signal indicates an increase in intensity of the ambient light 140 from a first intensity level to a second intensity level, over a specified time period, which is at least 50% higher than the first intensity level. The specified time period may for example be 1 minute, 10 minutes, or 1 hour. As a consequence of said determination, the controller 103 may increase the size of the luminous flux range 213, 223 from a first size of the luminous flux range to a second size of the luminous flux range. The second size of the luminous flux range may be at least 50% larger than the first size of the luminous flux range. The controller 103 may be configured to determine that the sensor signal indicates a decrease in intensity from the first intensity level to the second intensity level, over a specified time period, which is at least 50% lower than the first intensity level. As a consequence of said determination, the controller 103 may decrease the size of the luminous flux range 213, 223 from a first size of the luminous flux range to a second size of the luminous flux range. The second size of the luminous flux range may be at least 50% lower than the first size of the luminous flux range. In some embodiments said increase / decrease of the size of the luminous flux range 213, 223may be less than the determined increase / decrease in intensity indicated by the sensor signal. In other embodiments said increase / decrease of the size of the luminous flux range 213, 223may be more than the determined increase / decrease in intensity indicated by the sensor signal.

[0067] The controller 103 may be configured to determine that the sensor signal indicates an increase in CCT from a first CCT value to a second CCT value, over a specified time period, which is at least 500K higher than the first CCT value. As a consequence of said determination, the controller 103 may increase the size of the CCT range 213’, 223’ from a first size of the CCT range to a second size of the CCT range. The second size of the CCT range may be at least 500K larger than the first size of the CCT range. The controller 103 may be configured to determine that the sensor signal indicates a decrease in CCT from a first CCT value to a second CCT value, over a specified time period, which is at least 500K lower than the first CCT value. As a consequence of said determination, the controller 103 may decrease the size of the CCT range 213’, 223’ from a first size of the CCT range to a second size of the CCT range. The second size of the CCT may be at least 500K lower than the first size of the CCT range. In some embodiments said increase / decrease of the size of the CCT range 213’, 223’ may be less than the determined increase / decrease in CCT indicated by the sensor signal. In other embodiments said increase / decrease of the size of the CCT range 213’, 223’ may be more than the determined increase / decrease in CCT indicated by the sensor signal.

[0068] In some embodiments, the light source 101 comprises a plurality of LEDs. The plurality of LEDs may comprise a cool white LED and a warm white LED. The plurality of LEDs may comprise a red LED, a blue LED and a green LED. The plurality of LEDs may comprise a white LED, a red LED, a blue LED and a green LED. The plurality of LEDs may comprise a cool white LED, a warm white LED a blue LED and a green LED.

[0069] Figure 3 illustrates a further embodiment of a luminaire 300 comprising a lighting system 100 as summarized above. The luminaire 300 may further comprise a connector 301 mechanically and electrically connected to a socket of the luminaire. Such a luminaire provides the effects and advantages as summarized above.

Claims

CLAIMS:

1. A lighting system (100) comprising: a light source (101) for emitting a light output (150) having a luminous flux and a correlated color temperature, a user interface (104) for providing a user signal representing a lighting parameter, the lighting parameter being a desired luminous flux of the light output (150) and / or a desired correlated color temperature of the light output (150), a sensor (102) for providing a sensor signal representing an ambient parameter, the ambient parameter being an intensity and / or a correlated color temperature of ambient light (140), a controller (103) for receiving the sensor signal from the sensor (102) and for receiving the user signal from the user interface (104), wherein the controller (103) is configured to control, based on the user signal and the sensor signal, at least one of:(i) the luminous flux of the light output (150) to be in a luminous flux range from a lower luminous flux limit (211, 221) to an upper luminous flux limit (212, 222), the difference between the upper luminous flux limit (212, 222) and the lower luminous flux limit (211, 221) being a size of the luminous flux range (213, 223), and(ii) the correlated color temperature of the light output (150) to be in a correlated color temperature range from a lower correlated color temperature limit (211’, 221’) to an upper correlated color temperature limit (212’, 222’), the difference between the upper correlated color temperature limit (212’, 222’) and the lower correlated color temperature limit (211’, 221’) being a size of the correlated color temperature range (213, 223), and wherein the controller (103) is configured to adjust, dependent on the sensor signal, at least one of the luminous flux range and the correlated color temperature range.

2. The lighting system (100) according to claim 1, wherein the controller (103) is configured to: set the size of the luminous flux range (213, 223) to be constant,for a sensor signal that indicates a relatively high intensity (220) of the ambient light (140), set the upper luminous flux limit (222) and the lower luminous flux limit (221) to a relatively high luminous flux, respectively, and for a sensor signal that indicates a relatively low intensity (220) of the ambient light (140), set the upper luminous flux limit (212) and the lower luminous flux limit (211) to a relatively low luminous flux, respectively.

3. The lighting system (100) according to any one of the preceding claims, wherein the controller (103) is configured to: set the size of the correlated color temperature range (213’, 223’) to be constant, and for a sensor signal indicating a relatively high correlated color temperature (220’) of the ambient light (140), set the upper correlated color temperature limit (222’) and the lower correlated color temperature limit (221’) to a relatively high correlated color temperature (220’), respectively, and for a sensor signal indicating a relatively low correlated color temperature (210’) of the ambient light (140), set the upper correlated color temperature limit (212’) and the lower correlated color temperature limit (211’) to a relatively low correlated color temperature (210’), respectively.

4. The lighting system (100) according to any one of claims 1 to 3, wherein the controller (103) is configured to: set the size of the luminous flux range (213, 223) by setting the lower luminous flux limit (211, 221) and maintaining the upper luminous flux limit (212, 222) constant, and / or set the size of the correlated color temperature range (213’, 223’) by setting the lower correlated color temperature limit (211’, 221’) and maintaining the upper correlated color temperature limit (212’, 222’) constant.

5. The lighting system (100) according to any one of claims 1 to 3, wherein the controller (103) is configured to:set the size of the luminous flux range (213, 223) by setting the upper luminous flux limit (212, 222) and maintaining the lower luminous flux limit (211, 221) constant, and / or set the size of the correlated color temperature range (213’, 223’) by setting the upper correlated color temperature limit (212’, 222’) and maintaining the lower correlated color temperature limit (211’, 221’) constant.

6. The lighting system (100) according to any one of claims 1 to 3, wherein the controller (103) is configured to: set the size of the luminous flux range (213, 223) by setting the upper luminous flux limit (212, 222) and the lower luminous flux limit (211, 221), and / or set the size of the correlated color temperature range (213’, 223’) by setting the upper correlated color temperature limit (212’, 222’) and the lower correlated color temperature limit (211’, 221’).

7. The lighting system (100) according to any one of claims 1 and 4 to 6, wherein the controller (103) is configured to: for a sensor signal indicating a relatively high intensity (220) of the ambient light (140), set the size of the luminous flux range (223) to a relatively large size of the luminous flux range, and for a sensor signal indicating a relatively low intensity of the ambient light (140), set the size of the luminous flux range (213) to a relatively small size of the luminous flux range, and / or for a sensor signal indicating a relatively high correlated color temperature (220’) of the ambient light (140), set the size of the correlated color temperature range (223’) to a relatively large size of the correlated color temperature range, and for a sensor signal indicating a relatively low correlated color temperature (210’) of the ambient light (140), set the size of the correlated color temperature range (213’) to a relatively small size of the correlated color temperature range.

8. The lighting system (100) according to any one of the preceding claims, wherein the controller (103) is configured to set the size of the luminous flux range (213, 223) and the size of the correlated color temperature range (213’, 223’), wherein a ratio betweenthe size of the luminous flux range (213, 223) and the size of the correlated color temperature range (213’, 223’) is varied based on the sensor signal.

9. The lighting system (100) according to claim 8, wherein the controller (103) is configured to: for a sensor signal indicating a relatively high intensity and / or a relatively high correlated color temperature (220’) of the ambient light (140), set the size of the luminous flux range (213, 223) and / or the size of the correlated color temperature range (213’, 223’) such that a ratio between the size of the luminous flux range (213, 223) and the size of the correlated color temperature range (213’, 223’) is a relatively high value, and for a sensor signal indicating a relatively low intensity (210) and / or a relatively low correlated color temperature (210’) of the ambient light (140), set the size of the luminous flux range (213, 223) and / or the size of the correlated color temperature range (213’, 223’) such that a ratio between the size of the luminous flux range (213, 223) and the size of the correlated color temperature range (213’, 223’) is a relatively low value.

10. The lighting system (100) according to any one of the preceding claims, wherein the controller (103) is configured to determine that, over a specified time period: the sensor signal indicates an increase in intensity of the ambient light (140) from a first intensity level to a second intensity level that is at least 50 % higher than the first intensity level, and as a consequence of said determination increase the size of the luminous flux range (213, 223) from a first size of the luminous flux range to a second size of the luminous flux range that is at least 50 % larger than the first size of the luminous flux range, and / or the sensor signal indicates a decrease in intensity of the ambient light (140) from a first intensity level to a second intensity level that is at least 50 % lower than the first intensity level, and as a consequence of said determination decrease the size of the luminous flux range (213, 223) from a first size of the luminous flux range to a second size of the luminous flux range that is at least 50 % lower than the first size of the luminous flux range, and / or the sensor signal indicates an increase in correlated color temperature of the ambient light (140) from a first correlated color temperature value to a second correlated color temperature value that is at least 500 K higher than the first correlated color temperaturevalue, and as a consequence of said determination increase the size of the correlated color temperature range (213’, 223’) from a first size of the correlated color temperature range to a second size of the correlated color temperature range that is at least 500 K larger than the first size of the correlated color temperature range, and / or the sensor signal indicates a decrease in correlated color temperature of the ambient light (140) from a first correlated color temperature value to a second correlated color temperature value that is at least 500 K lower than the first correlated color temperature value, and as a consequence of said determination decrease the size of the correlated color temperature range (213’, 223’) from a first size of the correlated color temperature range to a second size of the correlated color temperature range that is at least 500 K lower than the first size of the correlated color temperature range.

11. The lighting system (100) according to claim 10, wherein: the increase of the size of the luminous flux range (213, 223) is less than the determined increase in intensity indicated by the sensor signal, and / or the increase of the size of the correlated color temperature range is less than the determined increase in correlated color temperature indicated by the sensor signal, and / or the decrease of the size of the luminous flux range (213, 223) is less than the determined decrease in intensity indicated by the sensor signal, and / or the decrease of the size of the correlated color temperature range is less than the determined decrease in correlated color temperature indicated by the sensor signal.

12. The lighting system (100) according to claim 10, wherein: the increase of the size of the luminous flux range is more than the determined increase in intensity indicated by the sensor signal, and / or the increase of the size of the correlated color temperature range is more than the determined increase in correlated color temperature indicated by the sensor signal, and / or the decrease of the size of the luminous flux range is more than the determined decrease in intensity indicated by the sensor signal, and / or the decrease of the size of the correlated color temperature range is more than the determined decrease in correlated color temperature indicated by the sensor signal.

13. The lighting system (100) according to any one of the preceding claims, wherein the size of the luminous flux range (213, 223) is at least 300 Im, and / or the size of the correlated color temperature range (213’ 223’) is at least 500 K.

14. The lighting system (100) according to any one of the preceding claims, wherein the light source comprises a plurality of LEDs, wherein the plurality of LEDs comprises one of the following combinations: a cool white LED and a warm white LED, - a red LED, a blue LED, and a green LED, a white LED, a red LED, a blue LED, and a green LED, a cool white LED, a warm white LED, a blue LED, and a green LED.

15. The lighting system (100) according to any one of the preceding claims, wherein the user interface comprises one or more sliders, one or more knobs, one or more push buttons, and / or one or more touch buttons.

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