WO2021148580A1

WO2021148580A1 - Determining light intensities for a plurality of leds which includes visible-light, uv-b and ir leds

Info

Publication number: WO2021148580A1
Application number: PCT/EP2021/051408
Authority: WO
Inventors: Rémy Cyrille BROERSMA; Bianca Maria Irma Van Der Zande; Marcus Theodorus Maria LAMBOOIJ; Tobias BORRA
Original assignee: Signify Holding B.V.
Priority date: 2020-01-23
Filing date: 2021-01-22
Publication date: 2021-07-29

Abstract

A method of controlling a plurality of LEDs comprises determining (161) a first intensity for one or more visible-light LEDs, determining (167) a second intensity for one or more UV-B LEDs, and determining (163,165) a third intensity for one or more IR LEDs. The method further comprises controlling (107) the one or more visible-light LEDs to generate a white spectrum at the first intensity, controlling (109) the one or more UV-B LEDs at the second intensity, and controlling (111) the one or more IR LEDs at the third intensity.

Description

Determining light intensities for a plurality of LEDs which includes visible-light, UV-B and IR LEDs

FIELD OF THE INVENTION

The invention relates to a system for controlling a plurality of LEDs, said plurality of LEDs comprising one or more visible-light LEDs for generating a white spectrum.

The invention further relates to a method of controlling a plurality of LEDs, said plurality of LEDs comprising one or more visible-light LEDs for generating a white spectrum.

The invention also relates to a computer program product enabling a computer system to perform such a method.

BACKGROUND OF THE INVENTION

The vitamin D3 hormone is a very important molecule that is produced in the skin with the help of UV-B light. It is a very versatile bio active molecule that impacts a very large number of genes in the human genome, and hence a large number of tissues and cells. Vitamin D3 insufficiency is increasingly linked to reduced health and wellbeing. There is a global epidemic (up to 90%) in vitamin D3 insufficiency, linked to a western lifestyle.

Hormonal supplements and food fortification are possible routes to improve vitamin D3 levels, but it has been shown that both have its limitations, in effectiveness and safety, compared to the natural process through outdoor cutaneous UV-B exposure. Natural sun exposure also has its large limitations, mainly due to large seasonal variations away from the equator, indoor lifestyle and the risk of sunburn and skin cancer. A supplementation using artificial UV-B light has benefits over alternative solutions. It is convenient to have the UV-B light rendered by a general illuminating device rendering white light, such as the one disclosed in WO2016/202736 Al.

Although the amount of UV-B needed to increase vitamin D levels in living animals and humans is very little and not considered dangerous, individuals can respond differently to the exposure of skin to UV. The risk of skin cancer (melanoma) for instance is linked to excessive cumulative sun exposure. Although excessive UV exposure can lead to DNA damage and possibly skin cancer, vitamin D itself is linked to a reduction of the probability of skin cancer (melanoma).

For indoor lighting applications, the amount of allowed UV-B light is bound to exposure limits defined in the photobiological standards (PBS). So, the amount of Vitamin D production is limited to the amount of UV-B light that is allowed in lighting systems.

SUMMARY OF THE INVENTION

It is a first object of the invention to provide a system, which helps increase a person’s vitamin D production without increasing the amount of rendered UV-B light.

It is a second object of the invention to provide a method, which helps increase a person’s vitamin D production without increasing the amount of rendered UV-B light.

In a first aspect of the invention, a system increasing vitamin D production in humans, said system for being configured to control a plurality of LEDs, said plurality of LEDs comprising one or more visible-light LEDs for generating a white spectrum, comprises at least one control interface and at least one processor configured to determine a first intensity for said one or more visible-light LEDs, determine a second intensity for one or more UV-B LEDs, determine a third intensity for one or more IR LEDs, control, via said at least one control interface, said one or more visible-light LEDs to generate said white spectrum at said first intensity, control, via said at least one control interface, said one or more UV-B LEDs at said second intensity, and control, via said at least one control interface, said one or more IR LEDs to generate wavelengths in the range 760-1400 nm and/or in the range 1401-3000 nm at said third intensity, said at least one processor being configured to control said plurality of LEDs to render, during at least one period, to simultaneously generate a UV-B spectrum and an IR spectrum.

Controlling (increasing) the skin temperature of a subject is an effective method to accelerate and increase vitamin D production without increasing the UV dose, as conversion of photosynthesized previtamin D3 to vitamin D3 is a temperature-dependent isomerization process. The rate of the isomerization reaction correlates directly with skin temperature. There are different components in the skin that through absorption can increase superficial skin temperatures: e.g. melanin, water, hemoglobin, fat. Using infrared (IR), preferably IR-A and/or IR-B, the skin temperature can be increased and hence vitamin D production in the skin can be accelerated using IR wavelengths. This helps increase a person’s vitamin D levels without increasing the amount of rendered UV-B light. Said at least one processor may be configured to control said one or more IR LEDs to generate wavelengths in the range 760-1400 nm and/or in the range 1401-3000 nm. The range 760-1400 nm (or 760-1399 nm) is also referred to as IR-A and Near-InfraRed (NIR). The range 1401-3000 nm (or 1400-3000 nm) is also referred to as IR-B and Short- Wavelength InfraRed (SWIR). Said at least one processor may be configured to control said UV-B LEDs to generate wavelengths in the range 280-320 nm.

Looking at IR wavelengths, a large area within the IR spectrum can be used to increase skin temperatures. Different wavelengths have different penetration depths and ideally only the top layer of the skin needs to be increased in temperature (skin surface and epidermis). It is beneficial to use IR wavelength ranges that are primarily available in natural sunlight, i.e. IR-A and IR-B. Wavelengths below 1100 nm are preferentially absorbed by melanin in the superficial layers of the skin. Wavelengths between 1400 and 1500 nm and those above 1850 nm are absorbed heavily by water in the superficial layers of the skin, which results in heating.

Said at least at least one processor may be configured to control said plurality of LEDs to render, during at least one period, light which looks white and simultaneously comprises a UV-B component and an IR component, said plurality of LEDs comprising said one or more UV-B LEDs and said one or more IR LEDs. This increases the subject’s skin temperature while at the same time increasing the subject’s vitamin D production.

Said at least one processor may be configured to control said one or more UV- B LEDs to generate said UV-B spectrum with a minimum standard erythemal dose of 0.01 per day. Said at least one processor may be configured to control said one or more UV-B LEDs to generate a UV-B spectrum with a maximum standard erythemal dose of 0.7 per day. This prevents or reduces the adverse effects of UV-B radiation.

Said system may further comprise a sensor interface and said at least one processor may be configured to obtain, via said sensor interface, a sensor measurement from a temperature measurement device, determine whether a person’s skin temperature exceeds a threshold based on said sensor measurement, determine said third intensity for said one or more IR LEDs such that said third intensity equals or exceeds a minimum upon determining that said skin temperature does not exceed said threshold, and determine said third intensity for said one or more IR LEDs such that said third intensity does not exceed said minimum upon determining that said skin temperature exceeds said threshold.

Since a skin temperature that is too high may be uncomfortable for the subject and may harm the subject’s health, it is beneficial to determine the intensity for the one or more IR LEDs based on a measured skin temperature. For example, the one or more IR LEDs may be switched off (an intensity of zero) as soon as the measured skin temperature exceeds the threshold. Said temperature measurement device may comprise an infrared camera, for example.

Said threshold may have a value between 29 and 37 degrees Celsius, e.g. a value between 31 and 35 degrees Celsius. A study using the (removed) skin of the lizard Iguana iguana, whose rate constant for the isomerization of previtamin D3 to vitamin D3 is similar to that of human skin, showed that isomerization occurs 9-fold more quickly at 25°C than at 5°C (50% of previtamin D3 converted to vitamin D3 (Tl/2) in 8 and 72 hours, respectively). At 37°C, the Tl/2 for the conversion of previtamin D to vitamin D in human skin decreases to 2.5 h. Under most normal conditions, human skin temperature is lower than core body temperature and varies between approximately 29°C and 35°C. The rate of cutaneous vitamin D synthesis will, in turn, vary as skin temperature fluctuates.

The afore-mentioned study has been described in “Evolutionary importance for the membrane enhancement of the production of vitamin D3 in the skin of poikilothermic animals” by Holick MF, Tian XQ, and Allen M, published in Proc Natl Acad Sci U S A 1995 Apr 11;92(8):3124-6, and in “Kinetic and thermodynamic studies of the conversion of previtamin D3 to vitamin D3 in human skin” by Tian XQ, Chen TC, Matsuoka LY, Wortsman J, and Holick MF, published in J Biol Chem. 1993 Jul 15;268(20): 14888-92.

Said at least one processor may be configured to determine said second intensity for said one or more UV-B LEDs based on said skin temperature. Higher skin temperatures allow for lower UV dose, which might be preferred in some cases.

Said at least one processor may be configured to control said one or more IR LEDs and said one or more UV-B LEDs to generate an IR spectrum in a pulsating manner while generating an UV-spectrum. Alternatively, said at least one processor may be configured to control said one or more IR LEDs and said one or more UV-B LEDs to generate an IR spectrum continuously while generating an UV-spectrum.

In a second aspect of the invention, a method increasing vitamin D production in humans, said system being configured to control a plurality of LEDs, said plurality of LEDs comprising one or more visible-light LEDs for generating a white spectrum, comprises determining a first intensity for said one or more visible-light LEDs, determining a second intensity for one or more UV-B LEDs, determining a third intensity for one or more IR LEDs, controlling said one or more visible-light LEDs to generate said white spectrum at said first intensity, controlling said one or more UV0B LEDs at said second intensity; and controlling said one or more IR LEDs to generate an IR-spectrum comprising wavelengths in the range 760-1400 nm and/or in the range 1401-3000 nm at said third intensity and during at least one period simultaneously with the generation of a UV-B spectrum. Said method may be performed by software running on a programmable device. This software may be provided as a computer program product.

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 or be stored upon manufacturing of these systems.

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 for controlling a plurality of LEDs, said plurality of LEDs comprising one or more visible-light LEDs for generating a white spectrum.

The executable operations comprise determining a first intensity for said one or more visible-light LEDs, determining a second intensity for one or more UV-B LEDs, determining a third intensity for one or more IR LEDs, controlling said one or more visible- light LEDs to generate said white spectrum at said first intensity, controlling said one or more UV-B LEDs at said second intensity, and controlling said one or more IR LEDs at said third intensity.

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, micro code, 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 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.

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.

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.

Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber, 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).

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 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 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.

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.

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. BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention are apparent from and will be further elucidated, by way of example, with reference to the drawings, in which:

Fig. 1 is a block diagram of a first embodiment of the system;

Fig. 2 shows a first example of light being rendered by the LEDs of Fig. 1 over time;

Fig. 3 shows a second example of light being rendered by the LEDs of Fig. 1 over time;

Fig. 4 is a block diagram of a second embodiment of the system;

Fig. 5 is a flow diagram of a first embodiment of the method;

Fig. 6 is a flow diagram of a second embodiment of the method;

Fig. 7 shows a third example of light being rendered by the LEDs of Fig. 1 over time; and

Fig. 8 is a block diagram of an exemplary data processing system for performing the method of the invention.

Corresponding elements in the drawings are denoted by the same reference numeral.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 shows a first embodiment of the system for controlling a plurality of LEDs: alighting device 1. The lighting device 1 comprises a receiver 3, a transmitter 4, a processor 5, a LED module 9 and a control interface 6 between the processor 5 and the LED module 9. The LED module 9 comprises a plurality of LEDs: a visible-light LED 11, an UV-B LED 12 and an IR LED 13.

The processor 5 is configured to determine a first intensity for the visible-light LED 11, determine a second intensity for the UV-B LED 12, determine a third intensity for the IR LED 13, control, via the control interface 6, the visible-light LED 11 to generate a white spectrum at the first intensity, control, via the control interface 6, the UV-B LED 12 at the second intensity, and control, via the control interface 6, the IR LED 13 at the third intensity. The terms white spectrum and white light relate to light having a correlated color temperature (CCT) between about 2000 K and 20000 K and within about 10 to 15 SDCM (standard deviation of color matching) from the BBL (black body locus).

A mobile device 25 is able to control the lighting device 1 via a wireless LAN access point 23 and a bridge 21, e.g. with the help of a light control app running on the mobile device 25. In the embodiment of Fig. 1, the mobile device 25 and the lighting device 1 communicate via the bridge 21. In an alternative embodiment, the mobile device 25 and the lighting device 1 can communicate directly, e.g. using Bluetooth technology.

In the embodiment of Fig. 1, the processor 5 is configured to obtain, via the receiver 3, a sensor measurement from a temperature measurement device 27. The processor 5 is further configured to determine whether a person’s skin temperature exceeds a threshold based on the sensor measurement, determine the third intensity for the IR LED 13 such that the third intensity equals or exceeds a minimum (e.g. 30 mW/m2 at skin level) upon determining that the skin temperature does not exceed the threshold, and determine the third intensity for the IR LED 13 such that the third intensity does not exceed the minimum upon determining that the skin temperature exceeds the threshold.

The temperature measurement device 27 may comprise an infrared camera, for example. Preferably, the threshold has a value between 29 and 37 degrees Celsius, e.g. between 31 and 35 degrees Celsius. In the embodiment of Fig. 1, the processor 5 is configured determine the second intensity for the UV-B LED 12 based on the skin temperature determined from the sensor measurement.

Thus, a feedback loop is present that determines the skin temperature and controls the intensity of the IR LED 13 in order not to exceed normal ranges of skin temperatures, e.g. 29-35°C and preferably maximum 37°C (depending on type of body parts, skin color type, activity, for example). In this embodiment, the feedback loop is also used to control the amount of UV-B based on the skin temperature to get to the same vitamin D synthesis. Higher skin temperatures allow for lower UV dose, which might be preferred in some cases. In an alternative embodiment, the amount of UV-B is additionally or alternatively based on the room temperature to get to the same vitamin D synthesis.

In the embodiment of Fig. 1, the temperature measurement device 27 and the lighting device 1 communicate via the bridge 21. In an alternative embodiment, the temperature measurement device 27 and the lighting device 1 can communicate directly, e.g. using Bluetooth technology.

Presence detection may be used to avoid unnecessary energy consumption by switching off one or more of the LEDs 11-13 when no one is present in the room or when a specific person is not at his desk.

The LEDs 11-13 may be direct emitting or phosphor converted LEDs. The visible-light LED 11 may be a white LED, for example. In the embodiment of Fig. 1, the LED module 9 comprises only one visible-light LED 11. In an alternative embodiment, the LED module 9 comprises multiple visible-light LEDs, e.g. a red LED, a green LED, a blue LED and optionally a white LED. In the embodiment of Fig. 1, the LED module 9 comprises only one UV-B LED 12. In an alternative embodiment, the LED module 9 comprises multiple UV-B LEDs.

The IR LED 13 may be an IR-A LED or an IR-B LED, for example. In the embodiment of Fig. 1, the LED module 9 comprises only one IR LED 13. In an alternative embodiment, the LED module 9 comprises multiple IR LEDs. These multiple IR LEDs may comprise one or more IR-A LEDs and/or one or more IR-B LEDs. The IR LED 13 may be switched on in a continuous mode or may be pulsed for high intensity IR sources (these wavelengths are not visible, so pulsing would not be noticeable). The amount of mW from the IR LED 13 is preferably at least 30 mW/m2 (at skin level) for period during a 24 hours cycle.

In the embodiment of the lighting device 1 shown in Fig. 1, the lighting device 1 comprises one processor 5. In an alternative embodiment, the lighting device 1 comprises multiple processors. The processor 5 of the lighting device 1 may be a general-purpose processor or an application-specific processor. The receiver 3 and the transmitter 4 may use one or more wireless communication technologies e.g. Zigbee, for communicating with the bridge 21. In an alternative embodiment, multiple receivers and/or multiple transmitters are used instead of a single receiver and a single transmitter.

In the embodiment shown in Fig. 1, a separate receiver and a separate transmitter are used. In an alternative embodiment, the receiver 3 and the transmitter 4 are combined into a transceiver. The lighting device 1 may comprise other components typical for a connected lighting device such as a power connector and a memory. In an alternative embodiment, the lighting device 1 is not a connected lighting device. The invention may be implemented using a computer program running on one or more processors.

In the embodiment of Fig. 1, the system of the invention is a lighting device.

In an alternative embodiment, the system of the invention is a different device, e.g. a mobile device. In the embodiments of Fig. 1, the system of the invention comprises a single device. In an alternative embodiment, the system of the invention comprises a plurality of devices.

Figs. 2 and 3 shows examples example of light being rendered by the LEDs of Fig. 1 over time. In both examples, the visible-light LED 11 renders white light 41 during a large portion of the day and the UV-B LED 12 and the IR LED 13 simultaneously render UV-B light 42 and IR light, respectively, during a short portion of the day. In the example of Fig. 2, the IR LED 13 renders IR light 43 continuously. In the example of Fig. 3, the IR LED 13 renders IR light 53 in a pulsating manner, e.g. every minute, at lHz or at 0. lHz. Thus, together, the LEDs 11-13 render light which looks white and simultaneously comprises a UV-B component and an IR component during a short portion of the day.

The IR light 43 and 53 comprises wavelengths in the range 760-1400 nm and/or in the range 1401-3000 nm. The UV-B light 42 comprises wavelengths in the range 280-320 nm. Preferably, the UV-B spectrum is generated with a minimum standard erythemal dose (SED) of 0.01 per day and with a maximum standard erythemal dose (SED) of 0.7 per day.

Fig. 4 shows a second embodiment of the system for controlling one or more light sources to render UV light: a mobile device 71. A lighting device 81 is capable of rendering white light and comprises visible-light LED 11 of Fig. 1. A lighting device 82 is capable of rendering UV-B light and comprises UV-B LED 12 of Fig. 1. A lighting device 83 is capable of rendering IR light and comprises IR LED 13 of Fig. 1. The lighting devices 81- 83 are co-located.

The mobile device 71 comprises a receiver 73, a transmitter 74, a processor 75, memory 77, and a display 79. The processor 75 is configured to determine a first intensity for the visible-light LED 11 of the lighting device 81, determine a second intensity for the UV-B LED 12 of the lighting device 82, determine a third intensity for the IR LED 13 of the lighting device 83, control, via the transmitter 74, the lighting device 81 to generate the white spectrum at the first intensity, control, via the transmitter 74, the lighting device 82 to generate the UV-B spectrum at the second intensity, and control, via the transmitter 74, the lighting device 83 to generate the IR spectrum at the third intensity.

The mobile device 71 is able to control the lighting devices 81-83 via the wireless LAN access point 23 and the bridge 21. In the embodiment of Fig. 4, the mobile device 71 and the lighting devices 81-83 communicate via the bridge 21. In an alternative embodiment, multiple of the mobile device 71 and the lighting devices 81-83 can alternatively or additionally communicate directly, e.g. using Bluetooth technology.

In the embodiment of Fig. 4, the lighting devices 81-83 each comprise only one LED. In an alternative embodiment, one or more of the lighting devices 81-83 comprise multiple LEDs, typically of the same kind (visible-light, UV-B or IR), as also described in relation to the LED module 9 of Fig. 1.

In the embodiment of the mobile device 71 shown in Fig. 4, the mobile device 71 comprises one processor 75. In an alternative embodiment, the mobile device 1 comprises multiple processors. The processor 75 of the mobile device 71 may be a general-purpose processor, e.g. from ARM or Qualcomm or an application-specific processor. The processor 75 of the mobile device 71 may run an Android or iOS operating system for example. The display 79 may comprise an LCD or OLED display panel, for example. The display 79 may be a touch screen display, for example. The memory 77 may comprise one or more memory units. The memory 77 may comprise solid state memory, for example.

The receiver 73 and the transmitter 74 may use one or more wireless communication technologies, e.g. Wi-Fi (IEEE 802.11) for communicating with the wireless LAN access point 23, for example. In an alternative embodiment, multiple receivers and/or multiple transmitters are used instead of a single receiver and a single transmitter. In the embodiment shown in Fig. 4, a separate receiver and a separate transmitter are used. In an alternative embodiment, the receiver 73 and the transmitter 74 are combined into a transceiver. The mobile device 71 may comprise other components typical for a mobile device such as a battery and a power connector. The invention may be implemented using a computer program running on one or more processors.

A first embodiment of the method of controlling a plurality of LEDs is shown in Fig. 5. The plurality of LEDs comprises one or more visible-light LEDs for generating a white spectrum, one or more UV-B LEDs, and one or more IR LEDs. A step 121 comprises determining intensities for the plurality of LEDs and comprises sub steps 101, 103 and 105. Step 101 comprises determining a first intensity for the one or more visible-light LEDs. Step 103 comprises determining a second intensity for the one or more UV-B LEDs. Step 105 comprises determining a third intensity for the one or more IR LEDs.

A step 123 comprises controlling the plurality of LEDs at the intensities determined in step 121. Step 123 comprises sub steps 107, 109 and 111. Step 107 comprises controlling the one or more visible-light LEDs to generate the white spectrum at the first intensity. Step 109 comprises controlling the one or more UV-B LEDs at the second intensity. Step 111 comprises controlling the one or more IR LEDs at the third intensity. Step 121 is repeated after step 123 and the method proceeds as shown in Fig. 5.

A second embodiment of the method of controlling a plurality of LEDs is shown in Fig. 6. A step 151 comprises receiving a signal representing user control input. The user control input may comprise a power-on, power-off, dim-up or dim-down command, for example. A step 161 comprises determining a first intensity for the one or more visible-light LEDs based on the signal received in step 151. Step 107 is performed after step 161 has been performed. Step 107 comprises controlling the one or more visible-light LEDs to generate white spectrum at the first intensity determined in step 161. A step 153 comprises obtaining a sensor measurement from a temperature measurement device and determining a person’s skin temperature STemp based on the sensor measurement. A step 167 comprises determining a second intensity for the one or more UV- B LEDs based on the skin temperature STemp determined in step 153. Step 109 is performed after step 167 has been performed. Step 109 comprises controlling the one or more UV-B LEDs at the second intensity determined in step 167.

A step 155 comprises determining whether the person’s skin temperature STemp exceeds a threshold T. Preferably, the threshold T has a value between 29 and 37 degrees Celsius, e.g. between 31 and 35 degrees Celsius. Step 163 is performed if it is determined in step 155 that the skin temperature STemp does not exceed the threshold T.

Step 163 comprises determining a third intensity for the one or more IR LEDs such that the third intensity equals or exceeds a minimum.

Step 165 is performed if it is determined in step 155 that the skin temperature STemp exceeds the threshold T. Step 165 comprises determining the third intensity for the one or more IR LEDs such that the third intensity does not exceed the minimum, e.g. by determining a third intensity of zero. Step 111 is performed after step 163 or step 165 has been performed. Step 111 comprises controlling the one or more IR LEDs at the third intensity determined in step 163 or 165.

Multiple changes have been made to the embodiment of Fig. 5 to obtain the embodiment of Fig. 6. In variations on these embodiments, only a subset of these changes is made. For example, in an alternative embodiment, the only change that is made to the embodiment of Fig. 5 is replacing step 103 of Fig. 5 with steps 153, 155, 163 and 165 of Fig. 6

Fig. 7 shows a third example of light being rendered by the LEDs of Fig. 1 over time. In the example of Fig. 7, the visible-light LED 11 renders white light 91 in the morning and white light 92 in the later afternoon and evening, the UV-B LED 12 renders UV-B light 93 and 94 around noon, and the IR LED 13 renders IR light 95 while the UV-B LED 12 is rendering UV-B light 93.

The visible-light LED 11 starts rendering white light 91 and 92 upon receiving a switch-on (SW1) user command and stops rendering white light 91 and 92 upon receiving a switch-off (SW0) user command. When the UV-B LED 12 starts rendering UV-B light, the measured skin temperature is 26 degrees Celsius. In the example of Fig. 7, a threshold of 31 degrees Celsius is used and as a result, the UV-B light is rendered at a higher intensity (UV-B light 93) and IR LED 13 is controlled to start rendering IR light 95. The next measured skin temperature is 29 degrees Celsius. Since this is still below the threshold of 31 degrees Celsius, no change is made to the rendering of the UV-B light 93 and the IR light 95.

The next measured skin temperature is 32 degrees Celsius. Since this is above the threshold of 31 degrees Celsius, the UV-B light is rendered at a lower intensity (UV-B light 94) and IR LED 13 is controlled to stop rendering IR light 95. The next measured skin temperature is 33 degrees Celsius. Since this is still above the threshold of 31 degrees Celsius, no change is made to the rendering of the UV-B light 94 and no IR light is rendered. The rendering of the UV-B light is stopped before the next skin temperature measurement is due. In the example of Fig. 7, the rendering of the UV-B light is stopped when the maximum daily dose has been rendered.

Fig. 8 depicts a block diagram illustrating an exemplary data processing system that may perform the method as described with reference to Figs. 5 and 6.

As shown in Fig. 8, the data processing system 300 may include at least one processor 302 coupled to memory elements 304 through a system bus 306. As such, the data processing system may store program code within memory elements 304. Further, the processor 302 may execute the program code accessed from the memory elements 304 via a system bus 306. 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 300 may be implemented in the form of any system including a processor and a memory that is capable of performing the functions described within this specification.

The memory elements 304 may include one or more physical memory devices such as, for example, local memory 308 and one or more bulk storage devices 310. 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 processing system 300 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 310 during execution. The processing system 300 may also be able to use memory elements of another processing system, e.g. if the processing system 300 is part of a cloud-computing platform.

Input/output (I/O) devices depicted as an input device 312 and an output device 314 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.

In an embodiment, the input and the output devices may be implemented as a combined input/output device (illustrated in Fig. 8 with a dashed line surrounding the input device 312 and the output device 314). An example of such a combined device is atouch 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.

A network adapter 316 may also be coupled to the data processing system to enable it to become coupled to other systems, computer systems, remote network devices, and/or remote storage devices through intervening private or public networks. The network adapter may comprise a data receiver for receiving data that is transmitted by said systems, devices and/or networks to the data processing system 300, and a data transmitter for transmitting data from the data processing system 300 to said systems, devices and/or networks. Modems, cable modems, and Ethernet cards are examples of different types of network adapter that may be used with the data processing system 300.

As pictured in Fig. 8, the memory elements 304 may store an application 318. In various embodiments, the application 318 may be stored in the local memory 308, the one or more bulk storage devices 310, or separate from the local memory and the bulk storage devices. It should be appreciated that the data processing system 300 may further execute an operating system (not shown in Fig. 8) that can facilitate execution of the application 318.

The application 318, being implemented in the form of executable program code, can be executed by the data processing system 300, e.g., by the processor 302. Responsive to executing the application, the data processing system 300 may be configured to perform one or more operations or method steps described herein.

Fig. 8 shows the input device 312 and the output device 314 as being separate from the network adapter 316. However, additionally or alternatively, input may be received via the network adapter 316 and output be transmitted via the network adapter 316. For example, the data processing system 300 may be a cloud server. In this case, the input may be received from and the output may be transmitted to a user device that acts as a terminal.

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 302 described herein.

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.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of embodiments of the present invention has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present invention. The embodiments were chosen and described in order to best explain the principles and some practical applications of the present invention, and to enable others of ordinary skill in the art to understand the present invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

CLAIMS:

1. A system (1,71) increasing vitamin D production in humans, said system being configured to control a plurality of LEDs (11-13), said plurality of LEDs (11-13) comprising one or more visible-light LEDs (11) for generating a white spectrum, said system (1,71) comprising: at least one control interface (6,74); and at least one processor (5,75) configured to:

- determine a first intensity for said one or more visible-light LEDs (11),

- determine a second intensity for one or more UV-B LEDs (12),

- determine a third intensity for one or more IR LEDs (13),

- control, via said at least one control interface (6,74), said one or more visible-light LEDs (11) to generate said white spectrum at said first intensity,

- control, via said at least one control interface (6,74), said one or more UV-B LEDs (12) at said second intensity, and

- control, via said at least one control interface (6,74), said one or more IR LEDs (13) to generate wavelengths in the range 760-1400 nm and/or in the range 1401-3000 nm at said third intensity, said at least one processor being configured to control said plurality of LEDs to render, during at least one period, to simultaneously generate a UV-B spectrum and an IR spectrum.

2. A system (1,71) as claimed in claim 1, wherein said at least at least one processor (5,75) is configured to control said plurality of LEDs (11-13) to render, during at least one period, light which looks white and simultaneously comprises said UV-B component and said IR component, said plurality of LEDs (11-13) comprising said one or more UV-B LEDs (12) and said one or more IR LEDs (13).

3. A system (1,71) as claimed in any one of the preceding claims, wherein said at least one processor (5,75) is configured to control said one or more IR LEDs (13) to generate wavelengths in the range 1400-1500 nm and/or in the range 1850-3000 nm.

4. A system (1,71) as claimed in any one of the preceding claims, wherein said at least one processor (5,75) is configured to control said one or more UV-B LEDs (12) to generate a UV-B spectrum with a maximum standard erythemal dose of 0.7 per day.

5. A system (1,71) as claimed in any one of the preceding claims, wherein said at least one processor (5,75) is configured to control said one or more UV-B LEDs (12) to generate said UV-B spectrum with a minimum standard erythemal dose of 0.01 per day.

6. A system (1) as claimed in any one of the preceding claims, wherein said system further comprises a sensor interface (3) and said at least one processor (5) is configured to:

- obtain, via said sensor interface (3), a sensor measurement from a temperature measurement device (27),

- determine whether a person’s skin temperature exceeds a threshold based on said sensor measurement,

- determine said third intensity for said one or more IR LEDs (13) such that said third intensity equals or exceeds a minimum upon determining that said skin temperature does not exceed said threshold, and

- determine said third intensity for said one or more IR LEDs (13) such that said third intensity does not exceed said minimum upon determining that said skin temperature exceeds said threshold.

7. A system (1) as claimed in claim 6, wherein said at least one processor (5) is configured to determine said second intensity for said one or more UV-B LEDs (12) based on said skin temperature.

8. A system (1) as claimed in claim 6 or 7, wherein said temperature measurement device (27) comprises an infrared camera.

9. A system (1) as claimed in any one of claims 6 to 8, wherein said threshold has a value between 29 and 37 degrees Celsius.

10. A system (1,71) as claimed in claim 9, wherein said threshold has a value between 31 and 35 degrees Celsius.

11. A system (1,71) as claimed in any one of the preceding claims, wherein said at least one processor (5,75) is configured to control said UV-B LEDs (12) to generate wavelengths in the range 280-320 nm.

12. A system (1,71) as claimed in any one of the preceding claims, wherein said at least one processor (5,75) is configured to control said one or more IR LEDs (13) and said one or more UV-B LEDs (12) to generate an IR spectrum in a pulsating manner while generating an UV-spectrum.

13. A system (1,71) as claimed in any one claims 1 to 11, wherein said at least one processor (5,75) is configured to control said one or more IR LEDs (13) and said one or more UV-B LEDs (12) to generate an IR spectrum continuously while generating an UV-spectrum.

14. A method increasing vitamin D production in humans, said system being configured to control a plurality of LEDs, said plurality of LEDs comprising one or more visible-light LEDs for generating a white spectrum, said method comprising:

- determining (101) a first intensity for said one or more visible-light LEDs;

- determining (103) a second intensity for one or more UV-B LEDs;

- determining (105) a third intensity for one or more IR LEDs;

- controlling (107) said one or more visible-light LEDs to generate said white spectrum at said first intensity;

- controlling (109) said one or more UV-B LEDs at said second intensity; and

- controlling (111) said one or more IR LEDs to generate an IR-spectrum comprising wavelengths in the range 760-1400 nm and/or in the range 1401-3000 nm at said third intensity and during at least one period simultaneously with the generation of a UV-B spectrum.

15. A computer program or suite of computer programs comprising at least one software code portion or a computer program product storing at least one software code portion, the software code portion, when run on a computer system, being configured for performing the method of claim 14.