Lighting device and method of operating the same

Abstract

The present disclosure relates to a lighting device and a method of operating the same, for providing white light in an environment depending on information indicative of a sleep state of a person in the environment. The lighting device comprises at least two LED light sources, wherein the at least two LED light sources comprise a first LED light source configured to provide, in operation, at least first blue light having a first spectral light distribution in a blue wavelength range, wherein the first blue light has a first emission peak wavelength, λ1, in a wavelength range 400 – 435 nm, and a second LED light source configured to provide, in operation, at least second blue light having a second spectral light distribution different from the first spectral light distribution, wherein the second blue light has a second emission peak wavelength, λ2, in a wavelength range 465 – 495 nm. A controller is configured to receive information indicative of a sleep state of a person in the environment and individually control a first intensity I1 of the first blue light and a second intensity I2 of the second blue light such that (i) when the received information indicates that the person in the environment is asleep, the device light provided by the lighting device is first white light W1 having a first intensity ratio I1 / I21 and a first correlated color temperature CCT1, and (ii) when the received information indicates that the person in the environment is awake, the device light provided by the lighting device is second white light W2 with a second intensity ratio I1 / I22 and a second correlated color temperature CCT2, wherein the first intensity ratio I1 / I21 is larger than the second intensity ratio I1 / I22 and the first correlated color temperature CCT1 is similar to the second correlated temperature CCT2.

Description

[0001] Lighting device and method of operating the same

[0002] FIELD OF THE INVENTION

[0003] The present disclosure relates to a lighting device and an operating method thereof. Examples of such devices include wake-up lighting devices, but the present disclosure is not limited thereto.

[0004] BACKGROUND OF THE INVENTION

[0005] The prior art comprises wake-up light devices which start emitting light before the auditory alarm clock signal occurs. The prior art wake-up lights typically increase the intensity of the emitted light over time, while some combine the wake-up related effects with the ambience creation of natural sunrise by mimicking the associated color changes in direct sunlight. During this wake-up period, a user can be expected to still be asleep and have the eyes closed, which means that light coming from the wake-up light device first must pass the eyelid before it becomes functional. In this time period preceding the user opening his eyes, conscious visual perception is not guaranteed, so the (sunrise) ambiance creation might go undetected until the eyes are opened.

[0006] In a scientific article from Katsuhisa Ando, Daniel F. Kripke (1996): Light attenuation by the human eyelid, Biological Psychiatry, Volume 39, Issue 1, the authors have evaluated eyelid transmission with a visual threshold response and found that estimated light transmission through the eyelids was 0.3% for blue, 0.3% for green, and 5.6% for red light. The eyelid therefore was an effective attenuator and acted as a red-pass filter.

[0007] It is known that when the eyes are closed and a person is looking at the back of the eyelids under white light exposure, red light can be seen, owing to a small amount of light penetrating the eyelids and taking on the color of the blood it has passed through.

[0008] WO 2016 / 096367 Al discloses a lighting device comprising a light source being configured to generate source light of a white light emission spectrum having a color correlated temperature (CCT) in a range of 2500-20000K and comprising a control unit being configured to control a lighting element for tuning of the source light with respect to a ratio between a first emission peak in a wavelength range of 460-490nm and a second emission peak in a wavelength range of 430-460nm. Thus a lighting device with a tunable / adjustable spectrum is provided that can switch between a first operation state of energy efficiency lighting with a blue peak in the second wavelength range of 430-460nm, but with blue hazard risk, and a second operation state of less efficient but safe, healthy lighting with a biological stimulant having a blue peak in the first wavelength range of 460-490nm.

[0009] EP 3 024 546 Bl discloses systems and methods to provide light therapy to a subject using one or more light sources configured to emit electromagnetic radiation in multiple stages using multiple wavelengths. By virtue of the emitted electromagnetic radiation impinging on the subject, the phase of the circadian rhythm of the subject is modified.

[0010] SUMMARY OF THE INVENTION

[0011] There are use cases or situations wherein a person wishes to have some white light available in the environment where the person is sleeping and while the person is sleeping, falling asleep of waking up. Such use cases may include: (a) a situation wherein a person wishes to have some background white light in the environment to improve safety, e.g., deterring burglars (b) a situation wherein a person wishes some form of dimmed night light, preferably dimmed white or whitish night light, for comfort, (c) a situation wherein some light needs to be available in case or when another person enters the environment where the person is asleep, or (d) in preparation for and / or during waking up of the person while the person has the eyelids still closed. In most of these use cases, it is desirable that the white light provided in the environment is not too disturbing for the person being asleep in the environment.

[0012] To address one or more of the use cases described above, an improved lighting device for providing white light in an environment is proposed wherein the lighting device comprises:

[0013] - at least two LED light sources, wherein the at least two LED light sources comprise:

[0014] * a first LED light source configured to provide, in operation, at least first blue light having a first spectral light distribution in a blue wavelength range, wherein the first blue light has a first emission peak wavelength, I, in a wavelength range 400 - 435 nm; and

[0015] * a second LED light source configured to provide, in operation, at least second blue light having a second spectral light distribution different from the first spectral light distribution, wherein the second blue light has a second emission peak wavelength, X2, in a wavelength range 465 - 495 nm, and

[0016] - a controller, configured to: * receive information indicative of a sleep state of a person in the environment; and

[0017] * individually control a first intensity II of the first blue light provided by the first LED light source and a second intensity 12 of the second blue light provided by the second LED light source,

[0018] - wherein the controller is further configured to:

[0019] * when the received information indicative of the sleep state of the person indicates that the person in the environment is asleep, control the first intensity II and the second intensity 12 such that, in operation, the device light provided by the lighting device is first white light W1 having a first intensity ratio 11 / I2i and a first correlated color temperature CCT1, and

[0020] * when the received information indicative of the sleep state of the person indicated that the person in the environment is awake, control the first intensity II and the second intensity 12 such that the device light provided by the lighting device is second white light W2 with a second intensity ratio 11 / 122 and a second correlated color temperature CCT2,

[0021] - wherein the first intensity ratio I1 / I21 is larger than the second intensity ratio 11 / 122 and the first correlated color temperature CCT1 is similar to the second correlated temperature CCT2.

[0022] Preferably, the first spectral light distribution of the first blue light from the first LED light source has a higher absorbance by the eyelid than the second spectral light distribution of the second blue light from the second LED light source and thus increasing the intensity ratio 11 / 12, i.e., replacing part of the second blue light with first blue light, in the white light results in a higher absorbance by the eyelid of the white light and thus a less disturbing white light for the person being asleep. Even more preferred wavelength ranges for the first spectral light distribution in the blue wavelength range and the second spectral light distribution in the blue wavelength range that make up the difference in absorbance by the eyelid are described further below.

[0023] Preferably, the second spectral light distribution of the second blue light from the second LED light source has a spectral light distribution closer to that of a blue light content in daylight, allowing the second white light to better mimic or approach the spectrum of natural light when the person is awake.

[0024] As a consequence, a more versatile lighting device is provided, that can be used while a person is asleep as well as while a person is awake, in both cases providing white light with a similar correlated color temperature. Additionally, the lighting device may exhibit the feature that the first CCT1 is similar to the second CCT2, when an absolute difference between the first CCT and the second CCT is equal to or less than 300K.

[0025] It is noted here that the first white light W1 and the second white light W2 may exhibit a correlated color temperature in a range from 1700K to 6500K, and preferably a color rendering index (CRI) of at least 80 or at least 85.

[0026] Additionally or alternatively, the lighting device may exhibit the feature that the first light source and second light source exhibit respective dominant peaks.

[0027] Additionally or alternatively, the lighting device may exhibit the feature that the first blue light from the first LED light source has a wavelength in a range preferably 410 - 425 nm, preferably in a range 415 - 420 nm. More in detail, this feature may relate to the first (dominant) emission peak wavelength of the used first LED light source.

[0028] Additionally or alternatively, the lighting device may exhibit the feature that the second blue light from the second LED light source has a wavelength in a range 475 - 490 nm, preferably in a range 480 - 485 nm. More in detail, this feature may relate to the second (dominant) emission peak wavelength of the used second LED light source.

[0029] Additionally or alternatively, the lighting device may exhibit the feature that it comprises at least one further LED light source configured to provide at least one other color light than blue light, wherein the controller is configured to control the first intensity II of the first LED light source, the second intensity 12 of the second LED light source and a third intensity 13 of the further LED light sources to generate the first white light and / or the second white light.

[0030] Additionally or alternatively, the lighting device may exhibit the feature that the first LED light source comprises at least one first blue LED chip and a first wavelength converter comprising a first luminescent material configured to partly convert first blue LED chip light emitted by said first blue LED chip into first converted light, the first white light comprises part of the first blue LED chip light and the first converted light; and the second LED light source comprises at least one second blue LED chip and a second wavelength converter comprising a second luminescent material configured to partly convert second blue LED chip light emitted by said second blue LED chip into second converted light, the second white light comprises part of the second blue LED chip light and the second converted light. Then, (i) the first converted light, (ii) the second converted light and / or (iii) the at least one other color light than blue light may comprise green-yellow or red light.

[0031] Additionally or alternatively, the lighting device may exhibit the feature that the controller is configured to, when the received information indicative of the sleep state of the person indicated that the person in the environment has recently woken-up or that the person is about to wake-up, the controller is configured to decrease intensity II of the first blue light, relative to when the person was asleep. Then, then the controller may be configured to increase the intensity 12 of the second blue light. The second blue light may exhibit improved melatonin suppression properties compared to the first blue light and therefore further improves the waking up process of the person. Especially the second spectral light distribution of the second blue light may exhibit an increased melanopsin sensitivity, melanopsin being the photo pigment in the human eye that is linked to the suppression of melatonin (also known as the sleep hormone) produced by the pineal gland and linked to improved alertness, compared to first spectral light distribution of the first blue light the wavelength range Additionally, or alternatively, the second spectral light distribution of the second blue light may better map with or resemble the blue light spectrum in natural daylight or natural morning light, than the first spectral light distribution of the first blue light, therewith presenting a more natural white light to the person when waking up or awake.

[0032] Additionally or alternatively, the lighting device may exhibit the feature that the controller is configured to receive information indicative of a sleep state of a second person in the environment near the at least one light source, wherein the controller is further configured to, when the information indicative of the sleep state of the second person indicates that the second person is awake, while the person is asleep, control the intensity II of the first LED light source, the intensity 12 of the second LED light source and the intensity 13 of the at least one further LED light source, when present, to emit the second white light. Although the second white light may exhibit a somewhat increased transmittance of the blue light through the closed eyelid (compared to the first white light), the person being asleep may not consciously notice the transition from the first white light to the second white light but the second person, being awake and having the eyelids open, will more consciously experience the better light quality, in terms of mimicking natural daylight, of the second white light.

[0033] Alternatively, the controller may be configured to receive information indicative of a sleep state of a second person in the environment near the at least one light source, wherein the controller is further configured to, when the information indicative of the sleep state of the second person indicates that the second person is awake, while the person is asleep, control the intensity II of the first LED light source, the intensity 12 of the second LED light source and the intensity 13 of the at least one further LED light source, when present, vary the white light between the first white light and the second white light. Then, the controller may be configured to vary between the first white light and the second white light at a frequency between 0,1 and 10 Hz. In this alternative, although the cyclic variations between the first white light and the second white light may have the disadvantage of being somewhat noticeable for the second person being awake, the cyclic variations may have the advantage of being unconsciously also noticeable to the person being asleep, especially if the frequency of variation between the first white light and the second white light results in perceivable luminous and / or chromatic flicker after the eyelid, i.e., for the person being asleep. Such flicker may be more perceivable with the eyelids closed (person being asleep) than with the eyelids open (person being awake) because of the absorption difference of the first blue light versus the second blue light by the eyelid. That is, after being filtered by the eyelid, the difference (intensity difference and / or spectral difference) between the first white light and the second white light may be larger than when viewed with the eyes open.

[0034] Additionally or alternatively, the lighting device may exhibit the feature that the first LED light source is configured to provide the first blue light having a property of exhibiting more than 10% tissue and / or blood absorbance, and the second LED light source is configure to provide the second blue light having a property of exhibiting less than 2,5 % tissue and / or blood absorbance.

[0035] Additionally or alternatively, the lighting device may exhibit the feature that the controller is configured to control the LED light sources of the lighting device to generate respective light that combines into white light having a color point of at least 7 SCDM above BBL. Because the transmission of blue and green light through the eyelid is substantially smaller than the transmission of red light through the eyelid, the white light having a color point of at least 7 SCDM above the BBL line may be perceived, after transmission through the eyelid, as white light having a color point closer the BBL and hence closer to natural white light.

[0036] Further, the present disclosure relates to a lighting system, comprising the above lighting device and a sensor configured to generate the information indicative of the sleep state of the person in the environment, wherein the sensor comprises one or more of a camera, a motion sensor, a physiological sensor, such as a breathing sensor or a heart rate sensor or an EEG sensor, Electrooculogram (EOG) sensor, or a Electromyogram (EMG) sensor, a skin conductance sensor, and a body temperature sensor. For information indicative of the sleep state the second person, a second sensor may be deployed, which may or may not be the same as the sensor deployed for the person.

[0037] Finally, the present disclosure relates to a method of operating an lighting device, comprising at least two LED lights sources, amongst which a first LED light source configured to provide at least first blue light having a first spectral light distribution in a blue wavelength range and a second LED light source configured to the provide at least second blue light having a second spectral light distribution in a blue wavelength range different from the first spectral light distribution, the method comprising:

[0038] - receiving information indicative of a sleep state of a person in an environment of the lighting device; and

[0039] - when the received information indicative of the sleep state of the person indicates that the person in the environment is asleep, control a first intensity II of the first blue light provided by the first LED light source and a second intensity 12 of the second blue light provided by the second LED light source such that the lighting device provides first white light W1 having a first intensity ratio 11 / 121 and a first correlated color temperature CCT1, and

[0040] - when the received information indicative of the sleep state of the person indicates that the person in the environment is awake, control the intensity II of the first blue light provided by the first LED light source and the intensity 12 of the second blue light provided by the second LED light source such that the lighting device provides second white light W2 with a second intensity ratio 11 / 122 and a second correlated color temperature CCT2,

[0041] - the first intensity ratio I1 / I21 is larger than the second intensity ratio 11 / 122 and the first correlated color temperature CCT1 is similar to the second correlated temperature CCT2.

[0042] In this respect it is noted here that the first white light W1 and the second white light W2 may exhibit a correlated color temperature in a range from 1700K to 6500K, and preferably a color rendering index (CRI) of at least 80 or at least 85.

[0043] Thus, a device and system referred to above and described in more detail hereinafter may be controlled using this method. The method may be executed, for example, by the controller described above and hereinafter. The controller may be a data processing system as described hereinafter. Moreover, a computer program for carrying out the methods described herein, as well as a non-transitory computer readable storage-medium storing the computer program are provided. A computer program may, for example, be downloaded by or uploaded to an existing device and executed by the controller of that device or be stored upon manufacturing of these devices and systems.

[0044] The lighting device, lighting system and / or method described herein operate based on information indicative of the sleep state of the person and indicating whether a person is ‘asleep’ or ‘awake’. Alternatively or additionally, the information indicative of the sleep state of the person may indicate that the person has the ‘eyelids closed’ or ‘eyelids opened’, which information may for example be captured by a camera, an EEG sensor, Electrooculogram (EOG) sensor, a Electromyogram (EMG) sensor or another sensor modality. The described lighting device, lighting system and / or method may indeed also be controlled based on this information, especially in periods in between a person being asleep and being awake, e.g., the period of waking up or falling asleep. However, information on the opened / closed status of the person’s eyelids may also be assumed from the asleep / awake status of the person. For example, the ‘eyelid closed’ status of a person’s eyelids may be exclusively linked with the ‘asleep’ status of the person, while any other sleep status, such as waking up, being awake or falling asleep, may assume the eyelid to be, at least partially or temporarily, opened. Other control options and / or decision criteria are of course possible and within scope of the disclosed lighting device, lighting system and method.

[0045] A non-transitory computer-readable storage medium stores at least one software code portion, the software code portion, when executed or processed by a computer, being configured to perform executable operations comprising: obtaining a target light level, determining a first set of light settings for a set of one or more lights and / or a first set of daylight blocker settings for a set of one or more daylight blockers based on said target light level, controlling said set of lights based on said first set of light settings and / or said set of daylight blockers based on said first set of daylight blocker settings, receiving from a user device information indicating a quality of a data signal received by said user device from one or more lights of said set of lights, said data signal being transmitted by modulating a light signal and said signal quality being determined by said user device, determining a second set of light settings for said set of lights based on said first set of light settings and said determined signal quality and / or a second set of daylight blocker settings for said set of daylight blockers based on said first set of daylight blocker settings and said determined signal quality, and controlling said set of lights based on said second set of light settings and / or said set of daylight blockers based on said second set of daylight blocker settings. As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a device, a method or a computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit", "module" or "system." Functions described in this disclosure may be implemented as an algorithm executed by a controller / processor / microprocessor of a computer. Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied, e.g., stored, thereon.

[0046] Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer readable storage medium may include, but are not limited to, the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of the present invention, a computer readable storage medium may be any tangible medium that can contain, or store, a program for use by or in connection with an instruction execution system, apparatus, or device.

[0047] A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0048] Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fibre, cable, RF, etc., or any suitable combination of the foregoing. Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java(TM), Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0049] Aspects of the present invention are described below with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a controller or processor, in particular a microprocessor or a central processing unit (CPU), of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the controller or processor of the computer, other programmable data processing apparatus, or other devices create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0050] These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0051] The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of devices, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0052] BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Aspects of the invention will be explained in greater detail by reference to exemplary embodiments shown in the drawings, in which:

[0054] Fig. 1 schematically illustrates an embodiment of a lighting system with a lighting device according to the present disclosure;

[0055] Fig. 2 schematically illustrates the absorption spectrum of haemoglobin in blood;

[0056] Fig. 3 schematically illustrates a colour space; and

[0057] Fig. 4 schematically illustrates a flow chart with steps of a method according to the present disclosure.

[0058] DETAILED DESCRIPTION OF THE DRAWINGS

[0059] Fig. 1 depicts a block diagram illustrating an exemplary lighting device 122 comprising a data processing system 100 that may be at the heart of the lighting device 122 and / or perform the method as described herein.

[0060] As shown in Fig. 1, the data processing system 100 may include at least one processor 102 for example coupled to memory elements 104 through a system bus 106. As such, the data processing system 100 may store program code within memory elements 104. Further, the processor 102 may execute the program code accessed from the memory elements 104 via a system bus 106. In one aspect, the data processing system may be implemented as a computer that is suitable for storing and / or executing program code. It should be appreciated, however, that the data processing system 100 may be implemented in the form of any system including a controller of the lighting device 122 that is capable of performing the functions described within this specification.

[0061] The memory elements 104 may include one or more physical memory devices such as, for example, local memory 108 and one or more bulk storage devices 110. The local memory may refer to random access memory or other non-persistent memory device(s) generally used during actual execution of the program code. A bulk storage device may be implemented as a hard drive or other persistent data storage device. The data processing system 100 may also include one or more cache memories (not shown) that provide temporary storage of at least some program code in order to reduce the quantity of times program code must be retrieved from the bulk storage device 110 during execution. The data processing system 100 may also be able to use memory elements of another processing system, e.g. if the data processing system 100 is part of a cloud-computing platform.

[0062] Input / output (I / O) devices depicted as an input device 112 and an output device 114 optionally can be coupled to the data processing system. Examples of input devices may include, but are not limited to, a keyboard, a pointing device such as a mouse, a microphone (e.g. for voice and / or speech recognition), or the like. Examples of output devices may include, but are not limited to, a monitor or a display, speakers, or the like. Input and / or output devices may be coupled to the data processing system either directly or through intervening I / O controllers.

[0063] In an embodiment, the input and the output devices may be implemented as a combined input / output device (illustrated in Fig. 1 with a dashed line surrounding the input device 112 and the output device 114). An example of such a combined device is a touch sensitive display, also sometimes referred to as a “touch screen display” or simply “touch screen”. In such an embodiment, input to the device may be provided by a movement of a physical object, such as e.g. a stylus or a finger of a user, on or near the touch screen display.

[0064] An adapter 116 may also be part of the data processing system to enable it to become coupled to other systems or devices such as the light sources and / or sensors, computer systems, remote network devices, and / or remote storage devices through intervening private or public networks. The adapter may comprise a data receiver for receiving data that is transmitted by said systems, devices and / or networks to the data processing system 100, and a data transmitter for transmitting data from the data processing system 100 to said systems, devices and / or networks. Modems, cable modems, and Ethernet cards are examples of different types of adapter that may be used with the data processing system 100.

[0065] As depicted in Fig. 1, the memory elements 104 may store an application 118. In various embodiments, the application 118 may be stored in the local memory 108, the one or more bulk storage devices 110, or separate from the local memory and the bulk storage devices. It should be appreciated that the data processing system 100 may further execute an operating system (not shown in Fig. 1) that can facilitate execution of the application 118. The application 118, being implemented in the form of executable program code, can be executed by the data processing system 100, e.g., by the processor 102. Responsive to executing the application, the data processing system 100 may be configured to perform one or more operations or method steps described herein.

[0066] In the shown embodiment of the lighting device 122, several LED lights sources 124, 126, 128 and 130 are connected to the data processing system 100 via the adapter 116. However, the LED light sources 124, 126, 128 and 130 may be connected to the data processing system 100 in any arbitrary manner, and may even be remote from the data processing system 100, for instance under the control of the data processing system 100 via a wireless connection.

[0067] Each of the LED light sources 124, 126, 128 and 130 emits, when so controlled, a single colour light in an intensity determined by the data processing system 100. The data processing system 100 is configured to drive the light sources 124, 126, 128 and 130 to emit in assembly a white light. The first LED light source 124 may emit a first blue light having wavelengths in a range 400 - 435 nm, more preferably 410 - 425 nm, and most preferably in a range 415 - 420 nm. More in detail, this feature may relate to the first (dominant) emission peak wavelength of the used first LED light source. The second LED light source 126 may emit a second blue light having wavelengths in a range 465 - 495 nm, more preferably 475 - 490 nm, and most preferably in a range 480 - 485 nm. More in detail, this feature may relate to the second (dominant) emission peak wavelength of the used second LED light source.

[0068] The remaining LED light sources 128 and 130 may emit yellow, red and / or green or any other light in an intensity and at a wavelength, under control of the data processing system 100, to combine with either or both of the first blue light and the second blue light from respectively the first blue LED light source 124 and the second blue LED light source 126 and blend into resulting first or second white light. To this end, data processing system 100 not only controls the first blue LED light source 124 and the second blue LED light source 126, but also actively drives the remaining LED light sources 128, 130 to combine into the first white light or the second white light.

[0069] Although a plurality of different LED light sources 124, 126, 128 and 130 are incorporated into the shown embodiment of lighting device 122, it is conceivable that a single LED light source may be controlled by data processing system 100 to generate and emit white light. Any one of the LED light sources 124, 126, 128 and 130 may comprise its own driver or other associated circuitry, or the data processing system 100 may be configured to form such drivers or other associated circuitry. The data processing system 100 may drive the LED light sources 124, 126, 128 and 130 to emit other visual or light effects, than white light.

[0070] The processor 102 may be configured to make the lighting device 122 function as a wake-up light. The lighting device 122 may be arranged in a room or any type of environment.

[0071] The data processing system 100 may receive a signal from a sensor 132, to provide the processor 102 with received information on a sleep state of a person in the environment. The sensor may be any type of sensor capable of providing such information to the data processing system 100, such as (but not limiting to) a camera, a motion sensor, a physiological sensor, such as a breathing sensor or a heart rate sensor or an EEG sensor, Electrooculogram (EOG) sensor, or a Electromyogram (EMG) sensor, a skin conductance sensor, and a body temperature sensor or even a smart watch worn by the person. The sensor 132 could even be a smart home appliance monitoring the person, for example utilizing a 60GHz mm-wave radar for sleep stage monitoring.

[0072] The sensor 132 may be incorporated into the lighting device 122. However, as is apparent from some of the above identified exemplary sensors that could be deployed to cooperate with the lighting device, the sensor may be connected to the lighting device by wire or wirelessly, and doesn’t need to be incorporated into the lighting device 122, but the lighting device 122 and the sensor 132 may cooperate as parts of a system, that is also subject of the present disclosure.

[0073] As noted above, the LED Light sources 124, 126, 128 and 130 are controlled by the data processing system 100. More in detail, the LED light sources are individually controlled by the data processing system 100. In particular, the first LED light source 124 may be controlled by the to emit the first blue light in an intensity II of the first LED light source 124. The second blue LED light source 126 may be controlled by the to emit the second blue light in an intensity 12 of the second LED light source. Further, the first blue LED light source 124 and the second blue LED light source 126 may be phosphor converted white light LEDs with different blue content. Alternatively, the first LED light source 124 may comprise at least one first blue LED chip and a first wavelength converter comprising a first luminescent material configured to partly convert first blue LED chip light emitted by said first blue LED chip into first converted light, the first white light comprises part of the first blue LED chip light and the first converted light. Then, the second LED light source 126 may comprise at least one second blue LED chip and a second wavelength converter comprising a second luminescent material configured to partly convert second blue LED chip light emitted by said second blue LED chip into second converted light, the second white light comprises part of the second blue LED chip light and the second converted light. Additionally or alternatively, (i) the first converted light, (ii) the second converted light and / or (iii) the at least one other color light than blue light comprises green, yellow and / or red light.

[0074] According to the present disclosure, the processor 102 may be configured to control the intensity II and the intensity 12 such that, in operation, the lighting device provides first white light with a first ratio 11 / 121 and a first correlated colour temperature (CCT), when it is determined that the person in the environment is asleep. This may be determined by the processor 102 based on the received information on the sleep state of the person. This information may originate from the sensor 132 or from elsewhere. Alternatively, when it is determined, based on the received information on the sleep state of the person, that the person in the environment is awake, the processor 102 may be configured to control the intensity II and the intensity 12 such that, in operation, the lighting device provides second white light with a second ratio 11 / 122 and a second CCT. The controller is further configured to ensure that the first ratio is larger than the second ratio and the first CCT is similar to the second CCT.

[0075] Thus, a higher degree of versatility is provided, because, while blue light in the wavelength range 400 - 435 nm, more preferably 410 - 425 nm, and most preferably in a range 415 - 420 nm is often referred to in prior art literature as causing a blue hazard risk, it can be safely used when the person is asleep with the eyes closed. It is noted that the prior art teaches away from using the first blue light in the wavelength range 400 - 435 nm, more preferably 410 - 425 nm, and most preferably in a range 415 - 420 nm, precisely because of the blue hazard risk. In contrast, the second blue light having a wavelength in a range 465 - 495 nm, more preferably 475 - 490 nm, and most preferably in a range 480 - 485 nm poses less of a blue hazard risk. Fig. 2 shows the absorption spectrum of haemoglobin in blood, which is closely linked to the absorption spectrum of the eyelid tissue as it is known that the eyelid has a rich vascular supply. From Fig. 2 it can be seen that wavelengths in the range of about 390- 430 nm are absorbed more than 10% by eyelid tissue and / or blood, whereas wavelengths in the range of about 450 - 540 nm are absorbed less than 2.5% by eyelid tissue and / or blood. Therefore, the first blue light in the aforementioned wavelength range of 400 - 435 nm is normally absorbed by eye lids of a person, in a degree of more than 10%. In contrast, the second blue light in the aforementioned wavelength in a range of 465 - 495 nm is less absorbed, more in particular to a degree of less than 2.5%.

[0076] When the data processing system 100 drives the first blue LED light source 124 to emit a higher intensity of first blue LED light II than the intensity 12 of the second blue light from the second LED blue light source, a resulting white light with a high concentration of the first blue light will be emitted, which doesn’t look as very natural or resemble normal daylight because it is lacking the long wavelength blue light intensity 12 that is present in daylight whereas the short wavelength blue light intensity II is disproportionate present in the white light.

[0077] FIG. 3 shows a graph of colour space, well known to a person skilled in the art.

[0078] Therein, a colour point (also chromaticity) of any light source may be characterised usually in the CIE standard colour system 1931. Each self-illuminating light source can be unambiguously specified by the x- and y coordinates thereof. The wavelengths visible to the human eye are plotted on the curved outer contour, or spectral locus. The lower limit is the purple line, which is the limit of visible light to invisible UV and IR radiation. The line in the centre of the diagram is marked by the black body locus (BBL). All of the colour points on the BBL are the colours of a black body radiator at different temperatures (Kelvin). These colours can be approximated using a mixture of a variety of visible wavelengths. The colour points on the BBL are differentiated by the mixing ratio of the wavelengths. If predominantly red wavelengths are present, this is referred to as warm white light. Cold white light, on the other hand, has a predominance of blue wavelengths.

[0079] On the BBL, the colour points of the colour temperatures are positioned from approximately 1000 K (Kelvin) to approximately 40,000 K. Light sources are referred to as warm white at < 3500 K, neutral white at 3500 K to 5000 K, and cold white light at > 5000 K. If the colour point of a white light source, i.e., not a black body radiator, is not on the BBL but close to the BBL, that colour point may be given a ‘correlated’ colour temperature CCT. The BBL is cut by the CCT (Correlated Colour Temperature) lines. These lines are formed from colour points of the same ‘correlated’ colour temperature, regardless of whether they are pure white, or tinted with another colour.

[0080] The term "white light" herein, is known to the person skilled in the art. It especially relates to light having a correlated colour temperature (CCT) between about 1800 K and 20000 K, especially 2700 - 20000 K, for general lighting especially in the range of about 2700 K and 6500 K, and especially within about 15 SDCM (standard deviation of colour matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL. Reference is made to the ANSI C78.377-2024 standard ‘Electric Lamps - Specification for the Chromaticity of Solid-State Lighting Products’ from 2024 for more detail.

[0081] According to the present disclosure, in a preferred embodiment, an absolute difference between the first CCT and the second CCT is equal to or less than 300K, in order for the first CCT and the second CCT to be similar, but another criterion may also be used. The second white light may be colder (to the left along the BBL) or warmer (to the right along the BBL) than the first white light. The first white light W1 and / or the second white light W2 may be on, above or below the BBL, as long as they qualify as white light according to the definition provided herein. One could draw a circle or ellipse around the colour temperature of the first white light at a distance corresponding with an absolute difference of 300 K or another appropriate difference value, to visualize or demarcate an area for the controller to aim at when driving the first, second and remaining LED light sources to emit - in assembly - the second white light. As an example in the graph of FIG. 3, and ellipse area 136 is drawn for the controller to aim at for assembling the second white light, when the first white light has a colour temperature at 2500K.

[0082] In this respect it is noted here that the first white light W1 and the second white light W2 may exhibit a correlated colour temperature in a range from 1700 K to 6500 K, and preferably a colour rendering index (CRI) of at least 80 or at least 85.

[0083] Further preferably, herein the first LED light source and second LED light source exhibit respective dominant peaks. These may he in the aforementioned wavelength ranges, more in detail, for the first blue light from the first LED light source a wavelength range 400 - 435 nm, more preferably 410 - 425 nm, and most preferably in a range 415 - 420 nm, and for the second blue light from the second LED light source a wavelength range 465 - 495 nm, more preferably 475 - 490 nm, and most preferably in a range 480 - 485 nm. As noted above, the devices 122 would not be capable of emitting white light, if only the two blue light emitting LED light sources 124 and 126 are provided. Therefore, the remaining LED light sources for emitting red and / or green (and / or other colour(s)) are required and actively controlled by the data processing system 100. The processor 102 may be configured to control an intensity of the first, second and further LED light sources to generate either the first white light or the second white light.

[0084] When it is determined, based on received information on the sleep state of the person, that the person in the environment has recently woken-up or that the person is about to wake-up, the processor 102 may be configured to decrease intensity II of the first blue light, relative to when the person was asleep. Thus, the blue hazard risk is reduced. The first blue light is only emitted in the first white light, as long as the person in the environment is asleep and the eyes of that person are closed. In order to control the resulting colour temperature of the second white light, the processor 102 may be configured to increase the intensity 12 of the second blue light, which may contribute in reducing the absolute difference between the colour temperatures of the first white light and the second white light, for example to below a difference of 300 K.

[0085] The data processing system 100 is preferably configured to control the LED light sources to generate the first white light having a colour point of at least 7 Standard Deviation of Colour Matching (SCDM) above BBL. In this manner, resulting white light, after having passed through and filtered by a sleeping person’s eyelid, resembles a colour temperature that is on the BBL and approximates sunlight observed with open eyes.

[0086] In use, a situation many occur in which a second person enters the environment, who is awake and may be near the at least one light source or approach the at least one light source. This may be detected and communicated to the controller by any means, for example using an exemplary embodiment of sensor 132, or other proximity detection device. For detection whether the second person is present, awake or asleep, an additional sensor may provide the information indicative of presence and sleep state of the second person, for example this second person’s smart phone, smart watch, or the like. Assuming that the (first) person is still asleep, the processor 102 may be configured to control the first LED light source, the second LED light source and - if any - further, additional or remaining LED light sources to - in assembly - emit the second white light. Thus, exposure of the second person to the first blue light in the environment may be avoided. Alternatively, when the second awake person is in the environment the processor 102 may be configured to, based on information that a second person is awake and near the at least one light source while the person is asleep, vary the light output between the first white light and the second white light. This may be done by intermittently emitting the first white light and the second white light. Then, the processor 102 may be configured to vary between the first white light and the second white light at a frequency between 0,1 and 10 Hz.

[0087] As noted above, the first blue light may exhibit more than 10% tissue and / or blood absorbance, which is a property of blue light in the wavelength range of about 400 - 430 nm, and the second blue light may exhibit less than 2,5 % tissue and / or blood absorbance which is a property of blue light in the wavelength range of about 450 - 500 nm. It is acknowledged that these absorption values may vary on an individual basis. However, as a general rule the characteristic of FIG. 2 will for any person exhibit a high absorption peak at shorter wavelengths in the blue light range and lower absorption vales in the longer wavelengths within the blue light range. Regardless of the intended aim of the present disclosure, at the heart thereof is a diversity of functionalities and possibilities that are unlocked by the possibility of assembling white light in different ways, using different wavelengths of blue light is that are differently absorbed by the eye lid and even using wavelengths of blue light in the blue hazard risk range.

[0088] In FIG. 4, a flow chart is exhibited to exemplify a method according to the present disclosure.

[0089] In FIG. 4 steps are shown of a method of operating a lighting device, for example the lighting device 122 in the system shown in FG. 1. The lighting device 122 comprises more than two LED lights sources, amongst which a first LED light source configured to provide at least first blue light, and a second LED light source configured to emit at least second blue light. Then, the method comprises a first step 401 of acquiring information on a sleep state of a person in an environment of the lighting device. In step 402, the method comprises determining, based on received information on the sleep state of the person in the environment or vicinity of the device 122, that the person in the environment is asleep. To arrive at such a determination, a signal may be used from the sensor 132 in FIG. 1. On the basis of the outcome of this determination, the method proceeds with individually controlling an intensity 11 of the first LED light source and an intensity 12 of the second LED light source.

[0090] When it is determined, based on received information on the sleep state of the person, that the person in the environment is asleep, in step 402 (‘Y’), the method proceeds in step 404 controlling the intensity II and the intensity 12 such that, in operation, the lighting device provides first white light with a first ratio H / I2i and a first CCT. However, when it is determined, based on received information on the sleep state of the person, that the person in the environment is awake, in step 402 (‘N’), the method proceeds in step 403 by controlling the intensity II and the intensity 12 such that, in operation, the lighting device provides second white light with a second ratio 11 / 122 and a second CCT.

[0091] Then, according to the present disclosure, the first ratio is larger than the second ratio and the first CCT is similar to the second CCT.

[0092] Optionally, when the method has determined that the person is asleep, information may be acquired about whether or not a second awake person may have entered the environment, and come in the vicinity of the device 122, in step 405. If the answer to this determination is in the affirmative - so at ‘Y’ after step 405 - the method may then proceed by controlling the intensity II and the intensity 12 such that, in operation, the lighting device provides second white light with the second ratio 11 / 122 and the second CCT by performing step 403, or may alternate between emitting the first white light by performing step 404 and the second white light by performing step 404. Additional determinations may be a check whether a first person in the environment has fallen asleep, or a check whether this first person has woken up, a check whether the second person who entered the environment has fallen asleep, and the like, and based on these determinations control the lighting device to either emit the first white light or the second white light depending on the sleep state of one of the persons present in the environment or close to the lighting device.

[0093] Various embodiments of the invention may be implemented as a program product for use with a computer system, where the program(s) of the program product define functions of the embodiments (including the methods described herein). In one embodiment, the program(s) can be contained on a variety of non-transitory computer-readable storage media, where, as used herein, the expression “non-transitory computer readable storage media” comprises all computer-readable media, with the sole exception being a transitory, propagating signal. In another embodiment, the program(s) can be contained on a variety of transitory computer-readable storage media. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., flash memory, floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. The computer program may be run on the processor 102 described herein.

[0094] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

Claims

CLAIMS1. A lighting device configured to provide device light in an environment, the lighting device comprising:- at least two LED light sources, wherein the at least two LED light sources comprise:* a first LED light source configured to provide, in operation, at least first blue light having a first spectral light distribution in a blue wavelength range, wherein the first blue light has a first emission peak wavelength, I, in a wavelength range 400 - 435 nm; and* a second LED light source configured to provide, in operation, at least second blue light having a second spectral light distribution different from the first spectral light distribution, wherein the second blue light has a second emission peak wavelength, X2, in a wavelength range 465 - 495 nm, and- a controller, configured to:* receive information indicative of a sleep state of a person in the environment; and* individually control a first intensity, II, of the first blue light provided by the first LED light source and a second intensity, 12, of the second blue light provided by the second LED light source,- wherein the controller is further configured to:* when the received information indicative of the sleep state of the person indicates that the person in the environment is asleep, control the first intensity, II, and the second intensity, 12, such that, in operation, the device light provided by the lighting device is first white light, Wl, having a first intensity ratio, I1 / I21, and a first correlated color temperature, CCT1, and* when the received information indicative of the sleep state of the person indicates that the person in the environment is awake, control the first intensity, II, and the second intensity, 12, such that the device light provided by the lighting device is second white light, W2, with a second intensity ratio, 11 / 122, and a second correlated color temperature, CCT2,- wherein the first intensity ratio, I1 / I21, is larger than the second intensity ratio, 11 / 122, and the first correlated color temperature, CCT1, is similar to the second correlated temperature, CCT2.

2. The lighting device of any preceding claim, wherein the first blue light has the first emission peak wavelength, I, in a wavelength range 410 - 425 nm, preferably in a range 415 - 420 nm.

3. The lighting device of any preceding claim, wherein the second blue light has the second emission peak wavelength, X2, in a wavelength range 475 - 490 nm, preferably in a range 480 - 485nm.

4. The lighting device of any preceding claim, further comprising at least one further LED light source configured to provide at least one other color light than blue light, wherein the controller is configured to control the first intensity, II, of the first LED light source, the second intensity, 12, of the second LED light source and a third intensity, 13, of the further LED light sources to generate the first white light and / or the second white light.

5. The lighting device of any preceding claim, wherein: the first LED light source comprises at least one first blue LED chip and a first wavelength converter comprising a first luminescent material configured to partly convert first blue LED chip light emitted by said first blue LED chip into first converted light, the first white light comprises part of the first blue LED chip light and the first converted light; and the second LED light source comprises at least one second blue LED chip and a second wavelength converter comprising a second luminescent material configured to partly convert second blue LED chip light emitted by said second blue LED chip into second converted light, the second white light comprises part of the second blue LED chip light and the second converted light.

6. The lighting device according to claim 4 or 5, wherein the first converted light, the second converted light and / or the at least one other color light than blue light comprises green-yellow and red light.

7. The lighting device of any preceding claim, wherein the controller is configured to, when the received information indicative of the sleep state of the person indicated that the person in the environment has recently woken-up or that the person is about to wake-up, the controller is configured to decrease intensity, II, of the first blue light, relative to when the person was asleep.

8. The lighting device of claim 7, wherein the controller is configured to increase the intensity, 12, of the second blue light.

9. The lighting device of any preceding claim, wherein the controller is configured to receive information indicative of a sleep state of a second person in the environment near the at least one light source, wherein the controller is further configured to, when the information indicative of the sleep state of the second person indicates that the second person is awake, while the person is asleep, control the intensity, II, of the first LED light source, the intensity, 12, of the second LED light source and the intensity, 13, of the at least one further LED light source, when dependent on claim 6, to emit the second white light.

10. The lighting device of any of claims 1 - 8, wherein the controller is configured to receive information indicative of a sleep state of a second person in the environment near the at least one light source, wherein the controller is further configured to, when the information indicative of the sleep state of the second person indicates that the second person is awake, while the person is asleep, control the intensity, II, of the first LED light source, the intensity, 12, of the second LED light source and the intensity, 13, of the further LED light source, when dependent on claim 6, vary the white light between the first white light and the second white light.

11. The lighting device of claim 10, wherein the controller is configured to vary the white light between the first white light and the second white light at a frequency between 0,1 and 10 Hz.

12. The lighting device of any of the preceding claims, wherein the first LED light source is configured to provide the first blue light having a property of exhibiting more than 10% tissue and / or blood absorbance, which is a property of blue light in the wavelengthrange of about 400 - 435 nm, and the second LED light source is configured to provide the second blue light having a property of exhibiting less than 2,5 % tissue and / or blood absorbance, which is a property of blue light in the wavelength range of about 465 - 495 nm.

13. The lighting device of any preceding claim, wherein the controller is configured to control the at least one light source to generate the first light, the second light and the third light to combine into white light having a color point of at least 7 SCDM above BBL.

14. A lighting system, comprising the lighting device of any preceding claim and a sensor configured to generate the information indicative of the sleep state of the person in the environment, wherein the sensor comprises one or more of a camera, a motion sensor, a physiological sensor, such as a breathing sensor or a heart rate sensor or an EEG sensor, Electrooculogram, EOG, sensor, or a Electromyogram, EMG, sensor, a skin conductance sensor, and a body temperature sensor.

15. A method of operating a lighting device, comprising at least two LED lights sources, amongst which a first LED light source configured to provide at least first blue light having a first spectral light distribution in a blue wavelength range, wherein the first blue light has a first emission peak wavelength, I, in a wavelength range 400 - 435 nm, and a second LED light source configured to the provide at least second blue light having a second spectral light distribution different from the first spectral light distribution, wherein the second blue light has a second emission peak wavelength, X2, in a wavelength range 465 - 495 nm, the method comprising:- receiving information indicative of a sleep state of a person in an environment of the lighting device; and- when the received information indicative of the sleep state of the person indicates that the person in the environment is asleep, control a first intensity, II, of the first blue light provided by the first LED light source and a second intensity, 12, of the second blue light provided by the second LED light source such that the lighting device provides first white light, Wl, having a first intensity ratio, I1 / I21, and a first correlated color temperature, CCT1, and- when the received information indicative of the sleep state of the person indicates that the person in the environment is awake, control the intensity, II, of the firstblue light provided by the first LED light source and the intensity, 12, of the second blue light provided by the second LED light source such that the lighting device provides second white light, W2, with a second intensity ratio, 11 / 122, and a second correlated color temperature, CCT2, - the first intensity ratio, I1 / I21, is larger than the second intensity ratio, 11 / 122, and the first correlated color temperature, CCT1 is similar to the second correlated temperature, CCT2.

Images