WO2022101057A1

WO2022101057A1 - Render of disinfectant light with ir and uv components

Info

Publication number: WO2022101057A1
Application number: PCT/EP2021/080365
Authority: WO
Inventors: Matthias Wendt; Peter Deixler
Original assignee: Signify Holding B.V.
Priority date: 2020-11-10
Filing date: 2021-11-02
Publication date: 2022-05-19
Also published as: EP4244541A1

Abstract

A system for controlling a set of one or more light sources of a lighting device (1) to provide disinfectant lighting is configured to determine a need for disinfectant lighting in an area and control at least one of the set of light sources to render a light effect (83) to provide the disinfectant lighting based on the need. The light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than said first time period.

Description

Render of disinfectant light with ir and uv components

FIELD OF THE INVENTION

The invention relates to a system for controlling a set of one or more light sources of a lighting device to provide disinfectant lighting.

The invention further relates to a method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting.

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

BACKGROUND OF THE INVENTION

As increased antibiotics-resistance of germs is predicted over the next 20 years, infection prevention is of high interest on the market. The benefits of episodic cleaning alone are short-lived as germs almost immediately re-populate the space. Hence, continuous preventive disinfection with LED based light disinfection is pursued by several US start-ups as well as established lighting companies such as Acuity, Current by GE and Hubbell. Some spectral components of light are known to reduce the speed at which pathogens grow or even to kill these.

In general, three different transmission ways of pathogens can be distinguished:

1. The “fomite” path, through touching a surface that contains the virus, such as a light switch, a door handle, or someone else’s hand. That can transfer the virus onto a person’s hand, and then the person can infect himself by touching his mouth, nostrils, or eyes.

2. The “large droplet” or “ballistic droplet” path. Droplets are particles of saliva or respiratory fluid (larger than about 100 pm) that are expelled from infected individuals when coughing, sneezing, and to a lesser extent, talking. They fly ballistically (like a projectile) through the air. They infect by landing on/in the mouth, nostrils, or eyes. If they do not hit someone, they fall to the ground in 1-2 meters (3-6 feet).

3. The “aerosol” path. Aerosols are also particles of saliva or respiratory fluid, but they are smaller than about 100 pm. For this reason, they can linger more in the air, from tens of seconds to hours, and can travel longer distances. They infect by being inhaled through the nose or mouth, or (less likely) by deposition on the eyes. Depending on their size, they stay longer / travel further in the air, and they also reach different parts of the human respiratory tract.

UV-C has been a proven technology for disinfecting air, water and instruments for over a century. Niels Finsen was awarded the Nobel Prize for Medicine in 1903 for being the first to use “light therapy” to treat disease with direct disinfection of skin. UV disinfection has been a domain of gas discharge lamps, but new LED components have been developed in recent years. For example, US 2019/0192710 Al discloses a disinfectant lighting device that renders UV-C light in an area where no human or animal presence is detected.

But not only developments in UV-C LEDs drive aspirations in the solid-state lighting industry for this attractive application. The drawback of UV-C light is that it is not friendly to humans or certain surfaces; as soon as the UV-C light is off when a person is present, the bacteria can grow again. Hence, recently companies have been looking for disinfection lighting alternatives which create an unfriendly space to bacteria while being friendly to humans.

For example, Hubbell Lighting and Kenall both apply UV-A technology licensed from the University of Strathclyde, which is eye-safe for continuous disinfection in the presence of human for up to 8 hours a day, unlike UV-C. Indigo-Clean from Kenall is an environmental disinfection device entirely in the visible spectrum that is integrated into lighting. Indigo-Clean is not UV light. Rather, it uses 405 nm visible purple light which is claimed to be safe for both patients and caregivers and to kill any bacteria that survives routine cleaning.

A drawback of these known disinfection lighting devices is that they do not work well in humid spaces, while humidity causes germs, e.g. mildew, to grow in many spaces.

SUMMARY OF THE INVENTION

It is a first object of the invention to provide a system, which can be used to disinfect humid spaces.

It is a second object of the invention to provide a method, which can be used to disinfect humid spaces.

In a first aspect of the invention, a system for controlling a set of one or more light sources of a lighting device to provide disinfectant lighting comprises at least one input interface, at least one control interface, and at least one processor configured to determine, via said at least one input interface, a need for disinfectant lighting in an area, and control, via said at least one control interface, at least one of said set of light sources to render a light effect provide said disinfectant lighting based on said need said light effect comprising IR light during a first time period and UV light during a second time period, said second time period ending later than said first time period. Said system may be a standalone controller, e.g. a bridge, or may be a component of the lighting device whose light sources it controls, for example. Said light spectrum may comprise UV-C (265-285nm) wavelengths, for example.

An advantage of light-based disinfection is that light-based disinfection works in the air, on both hard surfaces and on soft surfaces, while most of the conventional cleaning products only work on a portion of the surfaces on which bacteria can be found.

An advantage of using IR light to heat a surface before disinfecting it with UV light is that the UV light becomes more effective. This is especially beneficial in humid spaces in a building e.g. bathrooms, wellness areas, and pool areas. Bathrooms are generally considered to be the nastiest rooms in people’s homes. Similar, shared public spaces in swimming pools and gyms frequently cause infections. Even with diligent cleaning, bacteria, mold and mildew continue to live on people’s toilets, sinks and showers. Since germs eventually die on dry surfaces, disinfection of wet surfaces is a primary health concern. It is well known that wet surfaces (e.g. dressing room bench in a gym), moist environments, and biofilms (e.g., cooling towers, faucets and kitchen sinks, and equipment such as ventilators) are filled with germs.

Areas of attention within these humid spaces are bathtub, shower, toilet, lavatory, washbasin, faucet, gym changing room (typically adjacent to showers), and surfaces regularly touched by users. Dependent on the humidity in certain areas, additional disinfectant spectral components may be mixed into the disinfectant light. Sensors may be used to support the disinfection processes by giving information about surface wetness, air humidity temperature, and/or occupancy of the space.

Thus, the IR light helps evaporate the water film and therefore enables the UV light to more efficiently disinfect the surface once it is dried up. The absorption coefficient of the water plays a very important role in the effectiveness of the UV disinfection. The absorption coefficient describes how much light is lost as it travels through a medium and is reported in inverse centimeters; as the absorption coefficient increases, transmissivity decreases exponentially. While the absorption coefficient of pure distilled water is close to zero, natural organic matter, iron, nitrate and manganese absorb UV-C light and will increase the absorption coefficient of a water sample. Hence, a water covered surface will absorb some of the administered UV light (especially when the water is soapy/soiled) before reaching the to-be-disinfected surface underneath the water film. Research also shows that the absorption coefficient further increases when using 222nm Far UV compared to longer wavelength 254nm mercury bulbs and UV-A disinfection light.

The sequence of applying IR and UV light (and their associated doses) may be adaptively controlled based on the degree to which a water film is/remains present (measured, calculated based on duration/type of usage of the environment, assumed). The dosage of disinfection lighting (UV-only or combined with IR) may be controlled in view of earlier IR-only exposure.

The disinfectant light (effect) may be rendered as a (varying) sequence of light intensities. The sequence of light intensities may be varied in order to render pulsed disinfectant light. For a given dose of disinfectant lighting, a different pulse shape may be chosen. The disinfectant lighting may comprise visible light in addition to the UV and IR light. The visible light sometimes has a deactivation effect on certain pathogens (especially bacteria).

In this case, the pulsed disinfectant light, e.g. pulsed Xenon disinfection light (e.g. used by Xenex.com hospital disinfection robots), may also include visible light. This visible light may have different transitions in light intensities than the UV light. For example, the visible light may be generated by LEDs while the UV light may be generated by a conventional light source. Hence, different tradeoffs of light source efficiency versus pulse shape apply and the use of different slopes of the pulse for the UV light and the visible light may be beneficial. The pulsing of the visible light will normally only be done when no one is present in the room.

The IR light may also have a disinfectant effect. An advantage of using IR light as disinfection light is that it works better than UV light on certain surfaces and for certain pathogens. For example, it is well known that NIR disinfection (750-950 nm) achieves an 80% to 99.9% or 2-3 log reduction of the iron-dependent and some other types of bacteria and fungi. Furthermore, the absorption spectrum of each pathogen shows some distinct absorption peaks. Consequently, very specific IR wavelengths (frequencies) can be selected so as to ‘excite’ specific bond types in the specific molecules in the targeted pathogen. Moreover, in practical disinfection lighting conditions, the target surface may be partially blocked. While a certain material may be transparent at IR frequencies (e.g. thin plastic), it may not be transparent for 405nm or UV disinfection light. It is known that infrared light can pass through many materials which visible or UV light cannot pass through. However, the reverse is also true. There are some materials such as glass which can pass visible 405nm light but not infrared.

For instance, Far Infrared rays can penetrate into the human body tissue up to 1.5 to 2.8 inches while UV light is absorbed in the outer dead skin layer and hence cannot be felt. Similar, if a sheet of paper lies on the desk surface, IR will be scattered by the paper, but some of the IR light nevertheless will still pass through the paper and reaching the surface underneath the paper. Similarly, a space to be disinfected may be smoky such as a restaurant kitchen. Infrared light is known to travel well through thick smoke (e.g. infrared cameras are used by firefighters in smoke filled buildings).

In general, unlike UV light (e.g. 222nm Far-UV disinfection lighting), IR radiation can penetrate through materials and provide disinfection to surfaces occluded by the clutter material. On the other hand, due to lack of penetration of UV light through materials, UV-C kills microbes mostly on the surface of the products, in air or in light transparent water. While UV-C light kills biological molecules by attacking its genetic material, IR disinfection light has the ability to denature proteins and, in doing so, destroy the activity of the virus.

In addition, additional human-centric synergetic effects between IR and UV disinfection light sources, or other dual-functions of either the IR or UV, may be realized. For instance, the IR light source may further be used to provide warmth, according to a different setting, for heating up the floor of the changing room in a shared space such as a gym or in a residential bathroom. The IR light also may be used to provide wellness feeling by heating bodies in a room directly without heating up the air. Absorbing the heat into the skin, which feels like warm sun rays on a spring day is particularly relaxing incredibly comforting.

As an additional advantage, the IR light may be used to prevent mold or mildew. In many spaces in wet rooms, silicone sealing gets attacked by mildew and will ask for special treatment. The IR light may be used to heat up and dry the walls (instead of the air like conventional heaters) and hence provide a mold prevention function in times of high humidity (e.g. right after shower).

Said at least one processor may be configured to control, via said at least one control interface, at least one of said set of light sources to render said light effect in at least a light spectrum to provide said disinfectant lighting with a single light intensity or with a sequence of light intensities according to an optical output pattern based on said need, and control, via said at least one control interface, at least one of said set of light sources to render a further light effect in at least a further light spectrum to provide functional light at a further light intensity according to a further optical output pattern.

By letting a general lighting device render disinfectant light in addition to the normal functional light, more companies and consumers are expected to purchase a device that can render disinfectant light. Furthermore, combining these two lighting functions makes it possible to use components of the lighting device, e.g. the driver, not only to render the functional light, but also the render the disinfectant light, which is very efficient. By not only using a different light spectrum for the disinfectant light, but also a different light intensity and a different optical output pattern, the disinfectant lighting may be applied very efficiently.

The functional lighting typically comprises white light. A part of the white light spectrum is germicidally active and therefore the functional lighting may also have a minor disinfectant effect but separate from the disinfectant lighting.

Preferably, said optical output pattern is narrower than said further optical output pattern and/or said light intensity is higher than said further light intensity and/or said optical output pattern has a higher spatial uniformity than said further optical output pattern. For disinfection lighting, it is beneficial to have a higher spatial uniformity of the UV/IR dose compared to functional (white) light. This is to ensure that everywhere the targeted log-kill of bacteria is achieved. The required time for a surface disinfection cycle is typically determined by the most difficult surface in the room to disinfect. For instance, it may take 30 minutes to achieve a log 3 kill on the most difficult surface within the room compared to 5 minutes for the easiest surface in the room.

A surface can also become a difficult to disinfect surface when it is covered by a water film. Hence, using combined IR+UV light will result in faster disinfection cycles. For instance, the locker room in the gym with wet benches/floor may only need to be closed for 10 minutes to humans instead of for a 30-minute disinfection cycle with a conventional 254nm UV disinfection system without IR. If 222nm UV is used, the disinfection cycle can be run in the presence of people. In this case, it may be beneficial to run a disinfection cycle on each location in the locker room once approximately every hour. The disinfection system may time when to precisely administer the disinfection cycle based on human presence. As the IR light is perceived as pleasant for humans, the system may actuate the IR portion of the cycle when a person is present.

Said at least one processor may be configured to determine a humidity in said area, a humidity of an object in said area, or a thickness of a water film on a surface in said area and determine a duration of said first time period based on said humidity or said thickness of said water film. This makes it possible to determine how long IR light needs to be rendered to evaporate the water, but also makes it possible to determine how long the IR light can be rendered without damaging an object to be disinfected. Once the water surface is dried up, the IR light may need to be stopped before it overly heats up the surface and damages the materials or generates surface temperatures potentially hazardous to occupants of the space.

Research by Dr. Mengyu Yan from the University of Washington has shown that the combination of UV and IR light sources creates a synergistic effect for killing pathogens and the researcher proposes the IR+UV use in a disinfection flashlight. However, IR disinfection also has drawbacks: if a high IR dose is administered to an object, it may heat to a high temperature and therefore can damage the object. It is hence advantageous that the to-be-disinfected surface is covered by water film when applying the IR disinfection.

Said at least one processor may be configured to determine a rate at which said water film is disappearing and determine said duration of said first time period based on said rate.

Said at least one processor may be configured to determine whether said water film has a thickness of less than a threshold amount and to start rendering said UV light and/or stop rendering said IR light in dependence on said water film having a thickness of less than said threshold amount. The rendering of UV light has benefit as soon as the water film has disappeared sufficiently. The water film does not need to have disappeared completely; while the UV light has difficulty to penetrate through a thick layer of (soapy) water, it can penetrate a thin layer and disinfect the pathogens within the water as well as the pathogens on the underlying surface. The rendering of the IR light may stop at the same time the UV light starts or may stop when the water film has disappeared completely if rendering of the UV starts before the water film has disappeared completely, for example.

Said at least one processor may be configured to detect water in said area, determine whether said detected water is part of a body of water or part of a thin water layer, and control said at least one light source to render said IR light in dependence on whether said detected water is part of said body of water or part of said thin water layer. IR is normally not an effective disinfection means for a body of water.

Said at least one processor may be configured to control a system for heating, ventilating and/or air-conditioning said area to provide conditioned air during said first time period, e.g. warmer air and/or air with less humidity which hence will lead to more evaporation. For example, where if there is too much humidity to evaporate (quickly) with just IR light, an HVAC system may be controlled to provide conditioned air during the first time period to ensure the surface conditions required for successful surface disinfection.

Said at least one processor may be configured to detect a location of a water film and/or a current or anticipated location of a person in said area and determine an optical output pattern for rendering said IR light based on said location of said water film and/or said location of said person. The location of the water film may be determined by using RF -based sensing or by using structured light sensors to look at changes in surface reflectivity indicative of a water film, for example. IR light is experienced as pleasant by humans and it is therefore beneficial to render it in the direction of a person if possible. The current location of the person may be determined by using RF -based sensing or by using person recognition in camera images. The anticipated/future location of a person may be inferred based on context awareness. For instance, if a person in the gym is showering, he will come back afterwards to his locker. In this case, the bench there may be warmed up proactively for maximum comfort before he actually arrives at the bench.

Said at least one processor may be configured to detect human presence in said area and determine an optical output pattern, a single light intensity, a sequence of light intensities, a light spectrum, and/or a duration of said light effect in dependence on said detected human presence. This makes it possible to use the IR light to provide warmth if a person is present, e.g. for heating up the floor of the changing room in a shared space such as a gym or in a residential bathroom, and locally administer the warmth effect only on the spot where a person is present (e.g. a person sitting on the bench in the gym' s dressing room). For this, the dose and direction of the IR radiation may be chosen to illuminate the person' s exposed skin with a sufficiently comforting effect. The IR light also may be used to provide a wellness feeling by heating bodies in a room directly without heating up the air. Absorbing the heat into the skin, which feels like warm sun rays on a spring day, is particularly relaxing and comforting.

Said at least one processor may be configured to control a first one of said set of light sources to render said light effect in at least a first light spectrum at a first light intensity according to a first optical output pattern and control a second one of said set of light sources to render said light effect in at least a second light spectrum at a second light intensity according to a second optical output pattern, wherein said second light spectrum is different from said first light spectrum, said second light intensity is different from said first light intensity, and/or said second optical output pattern is different from said first optical output pattern.

For example, if a person has been detected and localized, a luminaire farther away from the person than another luminaire may be assigned the IR illumination task, because this luminaire can irradiate the person’s face, while the other luminaire can only irradiate the person’s back. When the person is gone, the IR task may be assigned to the other luminaire, because it is closest to the to-be-disinfected/to-be-dried surface and hence can generated the highest heat on it.

If a multitude of dual-mode luminaires capable of transmitting IR and UV lights are distributed across the room, assignment criteria on which disinfection mode to activate on each of the luminaires may take into account the distance to the target surface and/or a current context and/or user preferences. For instance, the luminaire assignment criteria may take into account the activities of a detected person. If a person has just taken a shower and his skin is wet, he will appreciate the comforting IR effect, while a fully dressed person may not care. Similarly, different people may have different preferences and the disinfection strategy may be personalized. For example, a first person may not want to be exposed by UV light while a second person does not like a strong IR effect on his skin but does not mind exposure to UV light.

In addition, the tradeoff between providing maximum comfort and maximum disinfection efficiency may be assessed based on the current risk of infection in the space due to past usage, e.g. recent events like someone close by having sneezed, thereby causing ballistic droplets deposited on the surface and hence requiring maximum disinfection.

Said at least one processor may be configured to determine one or more activities performed in said area and determine said need for disinfectant lighting in said area in dependence on a match between said one or more activities and one or more of a plurality of germ spreading activities. One or more of said plurality of germ spreading activities may relate to a microbial risk, for example. For instance, on a spot in the kitchen where raw meat is handled, there is typically an increased microbial risk. Germ spreading activities may include coughing and sneezing, for example. Coughing or sneezing may be detected by analyzing audio captured by a microphone, for example. Said at least one processor may be configured to detect presence of persons and/or animals in said area and determine said need for disinfectant lighting in said area in dependence on said presence or based on a duration of said presence and/or a count of how many different persons have been detected in said area.

Said at least one processor may be configured to determine a moment when a surface in said area was last cleaned and determine said need, a light intensity for said light effect, and/or a duration of said light effect based on said moment. For example, a need for disinfectant lighting may be determined to be present when a shower surface or other surface was not cleaned in the last six hours or the dose of the disinfectant lighting may be determined based on the moment of last cleaning and a bacteria growth rate.

Said at least one processor may be configured to determine one or more characteristics of a surface in said area and determine said need, a light intensity for said light effect, a light spectrum for said light effect, and/or a duration of said light effect based on said one or more characteristics. Said one or more characteristics of said surface may comprise surface material, surface texture, surface reflectivity, thickness of water film on said surface, volume of water on said surface, distribution of water on said surface, amount of soil in water on said surface, thermal conductivity of said surface, amount of dust on said surface, and/or amount of clutter on said surface, for example. For example, bacteria grow better on certain surfaces than on other surfaces and might not grow at all on certain surfaces. It may be beneficial to determine a distribution of water on the surface, because a surface topography may lead to puddles, e.g. there may be deeper water between tiles. It may be beneficial to determine an amount of soil in the water on the surface, because UV light has more difficulties to penetrate dirty water. It may be beneficial to determine the thermal conductivity of the surface, as it will be harder to heat it up a water film with IR and evaporate it on a highly thermally conductive surface than on a less thermally conductive surface.

Said at least one processor may be configured to obtain sensor information indicative of a measured concentration of a pathogen in said area and determine said need for disinfectant lighting in said area based on said concentration. The use of sensors to determine concentration of viruses or bacteria is typically the best way of determining germ risk. A light intensity for said light effect, a light spectrum for said light effect, and/or a duration of said light effect may depend on a type of said pathogen.

Said at least one processor may be configured to determine a location in said area at which a germ spreading activity may take place and determine an optical output pattern for said light effect based on said location. This allows the disinfectant lighting to be directed in the desired direction with a focused beam of relatively high intensity. The dose of the disinfectant lighting may be determined based on the determined location, e.g. a higher intensity may be used if the determined location is farther away from the lighting device.

Besides germ spreading activities, also certain environmental conditions promote rapid increase in germs, e.g. in salmonella.

In a second aspect of the invention, a method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting comprises determining a need for disinfectant lighting in an area and controlling at least one of said set of light sources to render a light effect to provide said disinfectant lighting based on said need, said light effect comprising IR light during a first time period and UV light during a second time period, said second time period ending later than said first time period. 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 set of one or more light sources of a lighting device to provide disinfectant lighting.

The executable operations comprise determining a need for disinfectant lighting in an area and controlling at least one of said set of light sources to render a light effect to provide said disinfectant lighting based on said need, said light effect comprising IR light during a first time period and UV light during a second time period, said second time period ending later than said first time period.

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 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. l is a block diagram of a first embodiment of the system;

Fig. 2 is a block diagram of a second embodiment of the system;

Fig. 3 depicts an example of a gym changing area comprising the system of Fig. 1 in which the first and second light effects are rendered;

Fig. 4 depicts an example of a home comprising the system of Fig. 2 in which the first and second light effects are rendered;

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 is a flow diagram of a third embodiment of the method;

Fig. 8 is a flow diagram of a fourth embodiment of the method;

Fig. 9 is a flow diagram of a fifth embodiment of the method;

Fig. 10 is a flow diagram of a sixth embodiment of the method; and

Fig. 11 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 set of one or more light sources to provide disinfectant lighting: a lighting 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 receiver 3, the transmitter 4, and the processor 5 are part of a control component 2. The LED module 9 comprises a plurality of LEDs: a visible-light LED 11 and an UV LED 12. Thus, the lighting device 1 comprises the light sources controlled by the control component 2.

The processor 5 is configured to control, via the control interface 6, the visible-light LED 11 to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern, determine, via the receiver 3, a need for disinfectant lighting in an area, and control, via the control interface 6, the UV LED 12 to render a second light effect in at least a second light spectrum to provide the disinfectant lighting at a second light intensity according to a second optical output pattern based on the need.

The second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. The IR light helps dry a surface or object in the area, thereby making the UV light more effective for disinfecting the surface or object. The IR light typically also has a disinfecting effect. The first and second periods may have some overlap, or the IR light and UV light may be rendered consecutively.

Application of far-infrared radiation may be issued for water films on surfaces. Intense, short-duration pulses increase the effectiveness of IR disinfection, whereby the germicidal effect appears to be due to both photochemical and photothermal effects. Several high intensity flashes of broad-spectrum light pulsed per second can inactivate microbes rapidly and effectively. Specifically, far-infrared rays are absorbed by water immediately after being radiated and may be used as energy for killing the bacteria because of the excellent temperature-rise and temperature-lowering characteristics associated with pulsed IR disinfection. For a pulsed IR disinfection, there is no significant rise in temperature of the hand skin surface and no skin burning occurred even after a 30-second pulsed IR irradiation period. Pulsed IR disinfection lighting is preferable if no heating effect of the skin is desired, while constant IR disinfection is preferable if the IR light is used to provide both disinfection and a warm wellness feeling.

In general, the term infrared refers to wavelengths above 750 nm, of which near infrared (NIR) describes wavelengths 750-1400 nm. IR Light sources are currently mostly used in IR saunas or life science application or for spectroscopic analysis purposes. Available IR solid state sources (LED or monolithic metal radiators) are available on the market with up to 1 W emissive power. • IR LEDs in the mid-range wavelength are commercially available, with center wavelengths from 1.9 gm (5263 cm-1) to 7 microns (1428 cm-1). Typical power levels are 10’s to 1000’s of microwatts.

• High power black body monolithic metal-based emitters are available from 2 pm (5000 cm-1) to 16 pm (625 cm-1) range.

In addition, administering the IR radiation in the presence of people will be felt by the person as, unlike UV light, very little infrared radiation is absorbed by the epidermis or dermis of the skin layers and thus IR light can penetrate deep into the body tissue and provide a wellness feeling. A beneficial side effect is that the IR radiation is also useful beyond disinfection to make objects (e.g. a toilet seat) not feel cold (this requires context aware control of the administered IR light).

In the embodiment of Fig. 1, the processor 5 is configured to obtain sensor information indicative of a measured concentration of a pathogen in the area from a sensor device 27 and determine the need for disinfectant lighting in the area based on the concentration. The second light spectrum, and/or a duration of the second light effect may depend on a type of the pathogen. In other words, the lighting device 1 is a combined luminaire for disinfectant spectrum as well as illumination spectrum which uses input from a sensor in order to assess the germ risk in an area and the need for the disinfection light.

The dose of the disinfectant light, i.e. the combination of the duration of the second light effect and the second light intensity, may be determined for a certain type of pathogen based on scientific publications. For example, the paper "How to use Ultraviolet light (UVC) to fight COVID-19 effectively in dental clinics" by Ajay Bajaj, Dental Tribune South Asia, May 12, 2020 (Online: https://in.dental-tribune.com/news/how-to-use- ultraviolet-light-uvc-to-fight-covid-19-effectively-in-dental-clinics-dr-aiay-baiai/) describes the D90 dose (exposure) required for several types of coronavirus.

Other examples of publications that describe UV dosage for deactivating pathogens are the UV Irradiation Dosage Table of American Air & Water (https://www.americanairandwater.com/uv-facts/uv-dosage.htm), and specifically for coronaviruses: “Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses” (https://www.nature.com/articles/s41598-020-67211-2) and “Ultraviolet irradiation doses for coronavirus inactivation - review and analysis of coronavirus photoinactivation studies” (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7273323/).

A biosensor for detecting the COVID-19 virus in the air has been described in the paper “A new biosensor for the COVID-19 virus” from the Swiss Federal Laboratories for Materials Science and Technology (EMPA). This optical biosensor for RNA uses two different effects to detect the virus safely and reliably: an optical and a thermal one, see https://www.sciencedaily.com/releases/2020/04/20042111252Q.htm.

A dose may be increased by increasing the light intensity, by increasing the duration of the disinfectant lighting, or by doing both. For example, instead of emitting UV-C light for one hour at 3.5W, UV-C light could be emitted for half an hour at 7W. The dosage needed for good results may be learned based on user feedback. For example, for every surface of interest, manual diagnosis measures may be used to find out the actual contamination once in a while and this may be fed into the system to adjust the estimation algorithms. This may lead, for each surface of interest, to an efficiency figure which may include distance as well as surface property.

In the embodiment of Fig. 1, the processor 5 is further configured to determine a location in the area at which a germ spreading activity may take place based on video data received from a camera device 29 and determine the second optical output pattern based on the location. The dose of the disinfectant light may be determined based on the determined location. The processor 5 may further be configured to determine a moment when a surface in the area was last cleaned based on the video data received from the camera device 29 and determine the need, the second light intensity, and/or a duration of the second light effect based on the moment.

In the example of Fig. 1, the sensor device 27 and the camera device 29 are connected to a wireless LAN access point 23, e.g. via Wi-Fi, and lighting devices 1 and 10 are also connected to the wireless LAN access point 23, e.g. via Wi-Fi. Lighting device 10 has the same components and is configured in the same way as lighting device 1. Lighting devices 1 and 10 are able to receive data from the sensor device 27 and the camera device 29 via the wireless LAN access point 23.

The LEDs 11-12 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 an alternative embodiment, the LED module 9 comprises no visible-light LEDs and the processor 5 is not configured to control a light source to render functional light. In the embodiment of Fig. 1, the LED module 9 comprises only one UV LED 12. In an alternative embodiment, the LED module 9 comprises multiple UV LEDs. In the embodiment of Fig. 1, the LED module 9 does not comprise an IR LED. In an alternative embodiment, the LED module 9 further comprises one or more IR LEDs.

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. Wi-Fi, for communicating with the wireless LAN access point 23. 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 controller. In the embodiment 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.

Fig. 3 depicts an example of a gym comprising the lighting devices 1 and 10 of Fig. 1 in which the first and second light effects are rendered. Fig. 3 shows the office at moments 71 and 72. The gym changing area comprises showers 73-76 in addition to the lighting devices 1 and 10, the sensor device 27 and the camera device 29. The gym changing area also comprises lockers 85 and 86 and benches 88 and 89.

At moment 71, lighting device 1 renders first light effect 81. The rendering of this functional lighting may start when a user switches on the light and stop when a user switches off the light. Alternatively or additionally, the rendering of this functional lighting may start as soon as the presence of a person is detected and stop when the presence of a person has not been detected for a certain amount of time. The functional lighting illuminates the entire office.

At moment 72, lighting device 1 renders second light effect 83. The rendering of this disinfectant lighting starts if a need for disinfectant lighting in an area has been determined and has not been (fully) addressed yet and may be started, for example, as soon as no person is present in the area. The presence of a person in the area may be detected using the camera device 29 or no person may be assumed to be present at certain times or when the office is dark (e.g. when no lights are on at night). For privacy reasons, the camera device 29 is not connected to any network or network device outside the gym changing area.

The lighting device 1 may determine, based on the video data from the camera device 29, that no one is present in the area covered by the lighting device 1 if no one is determined to be in shower 73 or 74. Alternatively, lighting device 1 may determine, based on the video data from the camera device 29, that no one is present in the area covered by the lighting device 1 if no presence is detected in the gym changing area.

Similarly, the lighting device 10 may determine, based on the video data from the camera device 29, that no one is present in the area covered by the lighting device 10 if no one is determined to be in shower 75 or 76. Alternatively, lighting device 10 may determine, based on the video data from the camera device 29, that no one is present in the area covered by the lighting device 10 if no presence is detected in the gym changing area.

IR light is rendered as first portion of the disinfectant lighting (during the first time period). As soon as any thin films of water are expected to have evaporated as a result of the IR light, UV light or a combination of UV light and IR light is rendered as second portion of the disinfectant light (during the second time period). The time at which the UV light is started, i.e. the start of the second time period, may be fixed, e.g. user-configurable, with respect to the start of the first time period or may depend on how long the showers 73-77 have been turned on, for example.

The rendering of the disinfectant light stops after a predetermined time expected to be enough to achieve the desired disinfectant effect and may also stop when presence is detected in the area covered by the lighting device. Signaling means or automated signage may be used to show occupants that the dose was (not yet) sufficient for disinfecting the area.

In the embodiment of Figs. 1 and 3, the lighting devices 1 and 10 determine the need for disinfectant lighting in the area based on the concentration of a pathogen in the area, as measured by sensor device 27. Furthermore, the lighting devices 1 and 10 determine a location in the area at which a germ spreading activity may take place based on video data received from a camera device 29 and determine the second optical output pattern of the disinfectant lighting based on this location. In an alternative embodiment, the second optical output pattern is configured by the installer who commissions the lighting devices 1 and 10. In the embodiment of Figs. 1 and 3, the lighting device 1 may determine the moment when the showers 73 and 74 were last cleaned based on the video data received from the camera device 29 and determine the second light intensity and/or a duration of the second light effect rendered by the lighting device 1 based on this moment. Similarly, the lighting device 10 may determine the determine a moment when the showers 75 and 76 were last cleaned based on the video data received from the camera device 29 and determine the second light intensity and/or a duration of the second light effect rendered by the lighting device 10 based on this moment. In an alternative embodiment, the moment when the showers 73-76 were last cleaned may be determined based on user input.

As shown in Fig. 3, the second optical output pattern of the disinfectant light (at moment 72) is narrower than the first optical output pattern of the functional light (at moment 71) and the second light intensity of the disinfectant light is also higher than the first light intensity of the functional light.

Fig. 2 shows a second embodiment of the system for controlling a set of one or more light sources to provide disinfectant lighting: a controller 41, e.g. a bridge or a gateway. In the example of Fig. 2, the controller 41 controls five lighting devices 51-55. In the example of Fig. 2, lighting devices 51-54 comprises a visible-light LED 11 and lighting device 55 comprise a visible-light LED 11, an UV LED 12, and an IR LED 13.

The controller 41 comprises a receiver 43, a transmitter 44, a processor 45, and memory 47. The processor 45 is configured to control, via the transmitter 44, at least one of the visible-light LEDs 11 of at least one of the lighting devices 51-55 to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern, determine, via the receiver 43, a need for disinfectant lighting in an area, and control, via the transmitter 44, the UV LED 12 and IR LED 13 of lighting device 55 to render a second light effect in at least a second light spectrum to provide the disinfectant lighting at a second light intensity according to a second optical output pattern based on the need.

The second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. In the embodiment of Fig. 2, the processor 45 is configured to determine a humidity in the area, a humidity of an object in the area, or a thickness of a water film on a surface in the area and determine a duration of the first time period based on the humidity or the thickness of the water film. The controller 41 first analyzes whether a surface of the to-be-disinfected object is presently wet before controlling a light source to render disinfectant light. In general, a system may directly monitor the surface of such an object for wetness with sensing means like e.g. a (remote) sensor. Alternatively, the system may analyze if there is humid/saturated air present in the room to such extent that a (thin) liquid film is covering the to-be-disinfected object. Thus, air humidity may be used as indication of condensation on surfaces or to infer that surfaces in the building space (e.g. changing room in a gym) must be wet right now. Optionally, the system may also determine whether the liquid film is soiled (i.e. soapy and hence further hampering the UV disinfection). If this is the case, then system may actuate the far-infrared disinfection. The time span of humid periods may be recorded in order to determine the duration of the second period, i.e. the duration of the UV disinfectant lighting.

The need for disinfectant light may be determined based on the presence of persons in the kitchen 85 and/or based on the volume of water detected in the kitchen 85, for example. Alternatively, the need for disinfectant light may be determined based on a measured concentration of a pathogen in the area. For example, for many different types of biosensors are available, as discussed in the article “ Electrochemical Biosensors for Rapid Detection of Foodbome Salmonella: A Critical Overview” by Cinti et al (published online on https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579882/).

The dose of the UV infectant lighting may be determined based on the moment the surface 99 was last cleaned. For example, based on the last manual cleaning and a well-known typical growth curve (see e.g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC169461/ for salmonella), the number of bacteria may be inferred.

IR light may not just be used for drying a surface, but also for disinfection, instead or in addition to the UV light. An example of this is described in the paper “Evaluation of Near-Infrared Pasteurization in Controlling Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Ready-To-Eat Sliced Ham” by Jae-Won Ha (published online on https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3426720/).

The humidity in the area, the humidity of the object in the area, or the thickness of the water film on the surface in the area may be determined by using RF -based sensing. The volume of water in the kitchen may also be determined by using RF-based sensing. Each of the lighting devices 51-55 may be able to transmit and/or receive RF signals and the differences between (e.g. the signal strength or the quality of) sets of signals received at different moments may be used to detect environmental changes between those moments, e.g. a person or animal entering a room or an increase or decrease in the humidity of a room.

The RF-based sensing may use the existing communication infrastructure like WiFi, ZigBee, or Bluetooth. It is known that RSSI and Relative Humidity (RH) show fully positively correlated time-based patterns. For instance, it has been shown that the relative Humidity has a very high positive correlation (0.95) with RSSI at 2.4GHz ZigBee, while interestingly, Absolute Humidity (AH) and RSSI are uncorrelated.

Therefore, the relative humidity in a room, e.g. the gym changing area of Fig. 3, may be determined by analyzing changes in RSSI. If the RSSI changes drastically in a bathroom, this may be assumed to indicate a shower. The system may then assume that a wet towel is present and therefore increase the disinfection light. The system may also predict the typical drying time of the towel, taking into account the estimated relative humidity in the room as well as the temperature.

A towel may be determined to be dry when the air humidity reaches a certain value, e.g. measured when sucking out the air. Drying by IR heating increases humidity in air. When the air humidity comes to a stable low value (ideally the same as air humidity of the intake air) then all surface and residual water has been dried away. Furthermore, testing has shown that a wet floor that resulted from mopping the floor may can be picked up with ZigBee RF-based sensing.

RF-based sensing may also be used to determine whether any fabrics (e.g. a towel) are still wet. A wet towel will modify the wireless multi-path propagation in the bathroom. Hence, a room with a wet towel will normally have a different WiFi CSI than the same room with a dry towel. 60GHz WiFi may be employed for the RF-based sensing. 60GHz mm-wave will be strongly absorbed by the moisture in the towel. WiFi beam steering may be employed to purposefully direct the WiFi wireless signal in the direction of the towel.

The humidity in the area, the humidity of the object in the area, or the thickness of the water film on the surface in the area may be determined by using structured light sensors to look at changes in surface reflectivity indicative of a water film instead of or in addition to the use of RF-based sensing.

In the example of Fig. 2, the lighting devices 51-55 are connected to the controller 41, e.g. using Zigbee. The controller 41 may be a Philips Hue bridge, for example. 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 example of Fig. 2, the lighting devices 51-55 comprise only one visible-light LED 11. In an alternative example, one or more of the lighting devices 51-55 comprise multiple visible-light LEDs, e.g. a red LED, a green LED, a blue LED and optionally a white LED.

In the example of Fig. 2, the lighting device 55 comprises only one UV LED 12 and only one IR LED 12. In an alternative example, the lighting device 55 comprises multiple UV LEDs and/or multiple IR LEDs. In the example of Fig. 2, the lighting device 55 comprises a visible-light LED 11. In an alternative example, the lighting device 55 does not comprise a visible-light LED.

In the embodiment of the controller 41 shown in Fig. 2, the controller 41 comprises one processor 45. In an alternative embodiment, the controller 41 comprises multiple processors. The processor 45 of the controller 41 may be a general -purpose processor, e.g. ARM-based, or an application-specific processor. The processor 45 of the controller 41 may run a Unix-based operating system for example. The memory 47 may comprise one or more memory units. The memory 47 may comprise one or more hard disks and/or solid-state memory, for example.

The receiver 43 and the transmitter 44 may use one or more wired or wireless communication technologies such as Zigbee to communicate with the lighting devices 51-55, 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. 2, a separate receiver and a separate transmitter are used. In an alternative embodiment, the receiver 43 and the transmitter 44 are combined into a transceiver. The controller 41 may comprise other components typical for a controller such as a power connector. The invention may be implemented using a computer program running on one or more processors.

Fig. 4 depicts an example of a home comprising the controller 41 and the lighting devices 51-55 of Fig. 2 in which the first and second light effects are rendered. Fig. 4 shows the home at moments 91 and 92. The home comprises a hallway 93, a kitchen 94, and a living room 95. Lighting devices 51-53 have been installed in the living room 95 and lighting devices 54-55 have been installed in the kitchen 94.

At moment 91, the lighting device 55 is controlled to render first light effect 85. The rendering of this functional lighting may start when a user switches on the light and stop when a user switches off the light. Alternatively or additionally, the rendering of this functional lighting may start as soon as the presence of a person is detected, e.g. using RF- based sensing, and stop when the presence of a person has not been detected for a certain amount of time. The functional lighting rendered by lighting devices 54 and 55 illuminates the entire kitchen 94.

At moment 92, the second light effect is rendered. For example, lighting device 55 is controlled to render light effect 87. The rendering of this disinfectant lighting starts if a need for disinfectant lighting in an area has been determined and has not been (fully) addressed yet and may be started, for example, as soon as no person is present in the area. The presence of a person in the area may be detected using RF -based sensing.

As previously described, the second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. The IR light helps dry a surface or object in the area, thereby making the UV light more effective for disinfecting the surface or object. The IR light typically also has a disinfecting effect. The first and second periods may have some overlap, or the IR light and UV light may be rendered consecutively.

In the embodiment of Figs. 2 and 4, the controller 41 determines a humidity in the area, a humidity of an object in the area, or an amount of water on a surface in the area and determines a duration of the first time period based on the humidity or the amount of water. For example, the humidity of the area may be determined by using RF -based sensing and this humidity may be assumed to represent the amount of water on a kitchen work surface 99 in the kitchen 94. In this example, the lighting device 52 may transmit RF signals that are received by lighting devices 54 and 55 and the signal strengths just received by lighting devices 54 and 55 may be compared with signal strengths received by lighting devices 54 and 55 from lighting device 52 at a reference time when the kitchen work surface 99 was completely dry and the level of humidity in the kitchen 94 was therefore low.

The IR light is then be used to dry the wet surface 99 and the dry surface 99 is then (further) disinfected using the UV light. The intensity of the IR light and the intensity of the UV light may be the same but could also be different. Typically, the intensity of the IR light and the intensity of the UV light are higher than the intensity of the visible-light light. As shown in Fig. 4, the second optical output pattern of the disinfectant lighting rendered by lighting device 85 (at moment 92) is narrower than the first optical output pattern of the functional lighting rendered by lighting device 85 (at moment 91) and the second light intensity of the disinfectant lighting is also higher than the first light intensity of the functional lighting.

In the example of Fig. 4, a dual -mode luminaire capable of transmitting IR and UV light has been installed in a kitchen. Such a dual-mode luminaire may also be installed in a bathroom to dry wet surfaces. In this case, the IR light may be also be applied during usage of the shower for an enhanced human centric shower experience.

The dual-mode luminaire or a separate device may also monitor the temperature of the treated surface (e.g. with a thermopile sensor). If the temperature is higher than a predefined threshold, the IR light may be switched off (temporarily) automatically. Optionally, a water nebulizer is included in the luminaire, which in combination with the IR light source may be used to generate moist heat in the room, which is particular efficient in viral disinfection and more volumetric.

In the example of Fig. 4, only one dual -mode luminaire is used. It is also possible to distribute a multitude of dual-mode luminaires (capable of transmitting IR and UV light) across a room. In this case, assignment criteria on which disinfection mode to activate on each of the luminaires given the distance to the target surface and/or the current context of the building space may be used. UV disinfection and IR disinfection light normally have different ranges. For instance, it is well known that water vapor significantly modulates the IR radiation, while UV radiation is affected less (mostly absorbed by ozone). Hence, if the radiation must be delivered from the luminaire over longer distance to the target surface in a room with currently high humidity, then it is advantageous to activate UV-based disinfection.

The assignment criteria may take into account the difference in reflectivity from metallic surfaces present in the specific room(s). For instance, aluminum has a relatively high and constant reflectance in the visible and IR range. Aluminum (sputtered on glass) has the highest reflectivity, but also aluminum paint can be very reflective. Other materials have a significantly higher reflectivity in the IR range than the UV range. In many situations, IR disinfection will be better able to reach a surface outside of the direct field of view of the disinfection light.

A first embodiment of the method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting is shown in Fig. 5. A step 101 comprises determining whether visible light is required, e.g. because a user has turned on the light. If it is determined in step 101 that visible light is required, a step 103 is performed. Step 103 comprises controlling at least one of the set of light sources to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern. After step 103, step 101 is repeated and the method proceeds as shown in Fig. 5. If it is determined in step 101 that visible light is not required, a step 105 is performed. Step 105 comprises determining a need for disinfectant lighting in an area. A step 107 is performed after step 105. Step 107 comprises checking whether a need for disinfectant lighting was determined in step 105 and no person is present in the area to be disinfected. If both are true, a step 109 is performed. Otherwise, step 101 is repeated and the method proceeds as shown in Fig. 5.

Step 109 comprises controlling at least one of the set of light sources to render a second light effect in at least a second light spectrum to provide the disinfectant lighting at a second light intensity according to a second optical output pattern. The second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. Preferably, the second optical output pattern is narrower than the first optical output pattern, the second light intensity is higher than the first light intensity, and/or the second optical output pattern has a higher spatial uniformity than the first optical output pattern. After step 109, step 101 is repeated and the method proceeds as shown in Fig. 5.

In the embodiment of Fig. 5, and also in the embodiments of Figs. 6-10, the disinfection light is temporarily de-activated when people are present. In an alternative embodiment, IR light is rendered while a person is present in the area to be disinfected and this may even provide comfort to this person. In this alternative embodiment or in another embodiment, UV light is rendered while a person is present, but the UV light intensity is reduced to a non-risky level if the presence of a person or animal is detected, e.g. using a sensor. In a bathroom, this UV-light may even ensure a white appearance of the towel(s). If UV light is rendered while a person is present, the visible part of the spectrum may be reduced when the area is not occupied by people, thereby increasing the disinfecting spectral components as no conversion is required.

A second embodiment of the method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting is shown in Fig. 6. Step 101 comprises determining whether visible light is required. If it is determined in step 101 that visible light is required, step 103 is performed. Step 103 comprises controlling at least one of the set of light sources to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern. After step 103, step 101 is repeated and the method proceeds as shown in Fig. 6.

If it is determined in step 101 that visible light is not required, step 105 is performed. Step 105 comprises determining a need for disinfectant lighting in an area. In the embodiment of Fig. 6, step 105 is implemented by steps 121 and 123. Step 121 comprises determining one or more activities performed in the area. Step 123 comprises determining the need for disinfectant lighting in the area in dependence on a match between the one or more activities determined in step 121 and one or more of a plurality of germ spreading activities. Step 123 further comprises determining the locations at which the one or more germ spreading activities determined in step 121 have taken place.

In the embodiment of Fig. 6, step 123 does not comprise detecting whether germs have actually been spread, but only whether germ spreading activities have taken place at which germs may have been spread. Step 107 is performed after step 105. Step 107 comprises checking whether a need for disinfectant lighting was determined in step 105 and no person is present in the area to be disinfected. If both are true, a step 125 is performed. Otherwise, step 101 is repeated and the method proceeds as shown in Fig. 6.

Step 125 comprises determining the second optical output pattern based on the one or more locations determined in step 123. Next, step 109 comprises controlling at least one of the set of light sources to render a second light effect in at least a second light spectrum to provide the disinfectant lighting at a second light intensity according to a second optical output pattern. The second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. After step 109, step 101 is repeated and the method proceeds as shown in Fig. 6.

A third embodiment of the method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting is shown in Fig. 7. A step 141 comprises detecting presence of persons and/or animals in an area. Next, a step 143 comprises logging the detected presence in a memory. Step 101 is performed after step 143.

Step 101 comprises determining whether visible light is required. If it is determined in step 101 that visible light is required, step 103 is performed. Step 103 comprises controlling at least one of the set of light sources to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern. After step 103, step 101 is repeated and the method proceeds as shown in Fig. 7.

If it is determined in step 101 that visible light is not required, step 105 is performed. Step 105 comprises determining a need for disinfectant lighting in an area. In the embodiment of Fig. 7, step 105 is implemented by steps 145 and 147. Step 145 comprises determining, based on the event data logged in step 143, a duration of the presence in the area and/or a count of how many different persons have been detected in the area. Step 147 comprises determining the need for disinfectant lighting in the area based on the duration and/or the count determined in step 145.

Step 107 is performed after step 105. Step 107 comprises checking whether a need for disinfectant lighting was determined in step 105 and no person is present in the area to be disinfected. If both are true, a step 149 is performed. Otherwise, step 101 is repeated and the method proceeds as shown in Fig. 7.

Step 149 comprises determining a moment when a surface in the area was last cleaned. This moment may be detected with a camera or determined based on user input, for example. Next, a step 151 comprises determine a second light intensity and/or a duration of a second light effect based on the moment determined in step 149. Step 109 is performed after step 151.

Step 109 comprises controlling at least one of the set of light sources to render the second light effect in at least a second light spectrum to provide the disinfectant lighting according to a second optical output pattern. The second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. The second light effect is rendered at the second light intensity determined in step 151 and/or with the duration determined in step 151. After step 109, step 101 is repeated and the method proceeds as shown in Fig. 7.

In the embodiment of Fig. 7, the need for disinfectant lighting is determined based on a duration of the presence in the area and/or a count of how many different persons have been detected in the area. In an alternative embodiment, the mere detection of presence in the area is sufficient to determine that there is a need for disinfectant lighting.

A fourth embodiment of the method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting is shown in Fig. 8. Step 101 comprises determining whether visible light is required. If it is determined in step 101 that visible light is required, step 103 is performed. Step 103 comprises controlling at least one of the set of light sources to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern. After step 103, step 101 is repeated and the method proceeds as shown in Fig. 8.

If it is determined in step 101 that visible light is not required, step 105 is performed. Step 105 comprises determining a need for disinfectant lighting in an area. In the embodiment of Fig. 8, step 105 is implemented by steps 149 and 171. Step 149 comprises determining a moment when a surface in the area was last cleaned. Step 171 comprises determining the need for disinfectant lighting in the area based on the moment determined in step 149.

Step 107 is performed after step 105. Step 107 comprises checking whether a need for disinfectant lighting was determined in step 105 and no person is present in the area to be disinfected. If both are true, step 109 is performed. Otherwise, step 101 is repeated and the method proceeds as shown in Fig. 8.

Step 109 comprises controlling at least one of the set of light sources to render a second light effect in at least a second light spectrum to provide the disinfectant lighting at a second light intensity according to a second optical output pattern. The second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. After step 109, step 101 is repeated and the method proceeds as shown in Fig. 8.

A fifth embodiment of the method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting is shown in Fig. 9. Step 101 comprises determining whether visible light is required. If it is determined in step 101 that visible light is required, step 103 is performed. Step 103 comprises controlling at least one of the set of light sources to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern. After step 103, step 101 is repeated and the method proceeds as shown in Fig. 9.

If it is determined in step 101 that visible light is not required, step 105 is performed. Step 105 comprises determining a need for disinfectant lighting in an area. In the embodiment of Fig. 9, step 105 is implemented by steps 201 and 203. Step 201 comprises determining one or more characteristics of a surface in the area. These one or more characteristics may be determined based on user input and/or detected using one or more sensors, for example.

The one or more characteristics of the surface may comprise surface material, surface texture, surface reflectivity, thickness of water film on the surface, volume of water on the surface, distribution of water on the surface, amount of soil in water on said surface, thermal conductivity of said surface, amount of dust on the surface, and/or amount of clutter on the surface, for example. For instance, if the surface is covered with TiO2 antimicrobial coating, there is very little risk. On the other hand, if the surface is often wet, it can be inferred that bacteria can grow well. The surface texture and/or dust and/or clutter may cause (micro) shadowing so that only reflected UV light can reach certain spots (i.e. no direct UV light in the shadowed areas). Optionally, step 201 also comprises determining a humidity in the area and/or a humidity of an object in the area. For example, sensors integrated with connected lighting devices may serve to provide information about air humidity and temperature. Step 203 comprises determining the need for disinfectant lighting in the area based on at least one of the one or more characteristics determined in step 201, e.g. based on the surface material.

Step 107 is performed after step 105. Step 107 comprises checking whether a need for disinfectant lighting was determined in step 105 and no person is present in the area to be disinfected. If both are true, a step 205 is performed. Otherwise, step 101 is repeated and the method proceeds as shown in Fig. 9. Step 205 comprises determining a second light intensity for a second light effect, a second light spectrum for the second light effect, and/or a duration of the second light effect based on at least one of the one or more characteristics determined in step 201. For example, a disinfection light may be rendered for a longer time and/or at a higher intensity if the amount of dust or clutter on the surface is relatively high.

A material has a specific surface topography; the surface topography creates micro shading effects i.e. a virus hiding in a surface cavity is hard to reach by the UV light making it hence difficult to deactivate with UV light. For instance, textile is much harder to disinfect with UV light than a smooth metal surface. Furthermore, a surface material dependent light recipe may be used. This reduces the aging effect of materials subjected to the disinfectant radiation as continuous radiation of UV deteriorates the object, which IR light does not deteriorate the object unless the object is heated to extreme temperatures by the IR radiation.

If an amount of water on the surface or a humidity exceeding a certain threshold has been detected in step 201, the second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. The IR light helps dry a surface or object in the area, thereby making the UV light more effective for disinfecting the surface or object. Optionally, step 205 comprises determining a duration of the first time period based on the humidity or the thickness of the water film determined in step 201, if applicable. Optionally, step 201 comprises determining a rate at which the water film is disappearing and step 205 comprises determining the duration of the first time period based on the rate.

The detection of a water film may be performed by means of local sensors attached at typically wet surfaces like e.g. shower cabin or seating in wellness areas. Small attachable (e.g. by means of adhesive, magnetic, vacuum suction techniques) sensor elements with integrated energy storage or energy scavenging means may be employed. The sensor elements are accessible through remote communication means, e.g. using Bluetooth, ZigBee Wi-Fi or passive Wi-Fi technology. Such sensors may be commissioned with the IR and UV light sources in the vicinity.

Dedicated sensors may be integrated in the hanging means for towels indicating the humidity of the garment. The walls near to crucial areas like the towel hanging space may reflect the active spectrum to enhance the reach the backside of the towel via reflection from the tiles.

It may be possible to use the sensors to track whether a thin layer of water has disappeared and then switch to (primarily) UV. In some embodiments the speed of how quickly a fluid layer dissipates may indicate how much humidity is now in the air. The sensors may be able to discriminate between a thin water layer (where the IR would be effective) and thick layers or even a body of water e.g. a puddle on the floor where IR radiation may not be sufficient to dry it or heat it sufficiently. The IR light may be controlled in dependence on whether the detected water is part of the body of water or part of the thin water layer.

In an alternative embodiment, airflow and air conditioning may be used to fight humidity. If there is too much humidity to evaporate with IR light, a Heating Ventilation and Air Conditioning (HVAC) system may be controlled in conjunction with the timing of the UV/IR such that the disinfectant light is most efficient. For example, if heating a water film by IR is scheduled, the cooling of a space may be delayed. Or when substantial amounts of water, e.g. a water puddle on the floor, are detected, airflow of conditioned air can be increased to increase the drying rate.

After step 205, step 109 comprises controlling at least one of the set of light sources to render the second light effect in at least a second light spectrum to provide the disinfectant lighting at a second light intensity according to a second optical output pattern. At least one of the second light spectrum, the second lighting intensity and the second optical out pattern was determined in step 205. Optionally, step 109 comprises determining whether the water film has disappeared and starting the rendering of the UV light and/or stopping the rendering of the IR light when the water film has disappeared. After step 109, step 101 is repeated and the method proceeds as shown in Fig. 9.

A sixth embodiment of the method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting is shown in Fig. 10. Step 101 comprises determining whether visible light is required. If it is determined in step 101 that visible light is required, step 103 is performed. Step 103 comprises controlling at least one of the set of light sources to render a first light effect in at least a first light spectrum to provide functional light at a first light intensity according to a first optical output pattern. After step 103, step 101 is repeated and the method proceeds as shown in Fig. 10.

If it is determined in step 101 that visible light is not required, step 105 is performed. Step 105 comprises determining a need for disinfectant lighting in an area. In the embodiment of Fig. 10, step 105 is implemented by steps 221 and 223. Step 221 comprises obtaining sensor information indicative of a measured concentration of a pathogen in the area. Step 223 comprises determining the need for disinfectant lighting in the area based on the concentration determined in step 221, e.g. in dependence on the concentration exceeding a threshold.

Step 107 is performed after step 105. Step 107 comprises checking whether a need for disinfectant lighting was determined in step 105 and no person is present in the area to be disinfected. If both are true, a step 225 is performed. Otherwise, step 101 is repeated and the method proceeds as shown in Fig. 10. Step 225 comprises determining a second light intensity for a second light effect, a second light spectrum for the second light effect, and/or a duration of the second light effect based on a type of the pathogen whose concentration was measured in step 221.

If the concentration of only one pathogen is measured in step 221, the second light intensity, the second light spectrum and the duration of the second light effect may be preconfigured, for example. If the concentrations of multiple pathogens are measured in step 221, the second light intensity, the second light spectrum and the duration of the second light effect may be obtained from a lookup table, for example. A dose corresponding to the type of a pathogen whose concentration exceeded the threshold may be looked up in this lookup table.

Next, step 109 comprises controlling at least one of the set of light sources to render the second light effect in at least a second light spectrum to provide the disinfectant lighting at a second light intensity according to a second optical output pattern. At least one of the second light spectrum, the second lighting intensity, and the duration of the second light effect was determined in step 225. The second light effect comprises IR light during a first time period and UV light during a second time period. The second time period ends later than the first time period. After step 109, step 101 is repeated and the method proceeds as shown in Fig. 10. In the embodiments of Figs. 5 to 10, the method comprises controlling at least one light source to provide functional lighting in step 103. In an alternative embodiment, steps 101 and 103 are omitted.

The embodiments of Figs. 5 to 10 differ from each other in multiple aspects, i.e. multiple steps have been added or replaced. In variations on these embodiments, only a subset of these steps is added or replaced and/or one or more steps is omitted. For example, steps 149 and 151 may be omitted from the embodiment of Fig. 7 and/or added to the embodiment of Fig. 6.

Fig. 11 depicts a block diagram illustrating an exemplary data processing system that may perform the method as described with reference to Figs. 5 to 10.

As shown in Fig. 11, 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. 11 with a dashed line surrounding the input device 312 and the output device 314). 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.

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. 11, 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. 11) 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. 11 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

36 CLAIMS:

1. A system (2,41) for controlling a set of one or more light sources (11-13) of a lighting device (1,10, 51-55) to provide disinfectant lighting for humid spaces in a building, said system (2,41) comprising: at least one input interface (3,43), at least one control interface (6,44); and at least one processor (5,45) configured to:

- determine, via said at least one input interface (3,43), a need for disinfectant lighting in an area,

- determine, based on user input and/or detected using one or more sensors, a humidity in said area, a humidity of an object in said area, or a thickness of a water film on a surface in said area,

- determine a duration of a first time period, during which at least one of said set of light sources is controlled to render a light effect comprising IR light, based on said humidity or said thickness of said water film; and

- control, via said at least one control interface (6,44), at least one (12,13) of said set of light sources (11-13) to render said light effect to provide said disinfectant lighting based on said need, said light effect comprising IR light during said first time period and UV light during a second time period, said second time period ending later than said first time period.

2. A system as claimed in claim 1, wherein said at least one processor (5,45) is configured to:

- control, via said at least one control interface (6,44), at least one (12,13) of said set of light sources (11-13) to render said light effect in at least a light spectrum to provide said disinfectant lighting with a single light intensity or with a sequence of light intensities according to an optical output pattern based on said need, and

- control, via said at least one control interface (6,44), at least one (11) of said set of light sources (11-13) to render a further light effect in at least a further light spectrum 37 to provide functional light at a further light intensity according to a further optical output pattern.

3. A system (2,41) as claimed in claim 2, wherein said optical output pattern is narrower than said further optical output pattern and/or said single light intensity is higher than said further light intensity and/or said optical output pattern has a higher spatial uniformity than said further optical output pattern.

4. A system (2,41) as claimed in claim 1, wherein said at least one processor

(5,45) is configured to determine, based on said user input and/or detected using said one or more sensors, a rate at which said water film is disappearing and determine said duration of said first time period based on said rate.

5. A system (2,41) as claimed in claim 1, wherein said at least one processor

(5,45) is configured to determine, based on said user input and/or detected using said one or more sensors, whether said water film has a thickness of less than a threshold amount and to start rendering said UV light and/or stop rendering said IR light in dependence on said water film having a thickness of less than said threshold amount.

6. A system (2,41) as claimed in claim 1 or 2, wherein said at least one processor

(5,45) is configured to detect, based on said user input and/or detected using said one or more sensors, water in said area, determine whether said detected water is part of a body of water or part of a thin water layer, and control said at least one light source to render said IR light in dependence on whether said detected water is part of said body of water or part of said thin water layer.

7. A system (2,41) as claimed in claim 6, wherein said at least one processor

(5,45) is configured to control a system for heating, ventilating and/or air-conditioning said area to provide conditioned air during said first time period.

8. A system (2,41) as claimed in claim 1 or 2, wherein said at least one processor

(5,45) is configured to detect, based on said user input and/or detected using said one or more sensors, a location of a water film and/or a current or anticipated location of a person in said area and determine an optical output pattern for rendering said IR light based on said location of said water film and/or said current or anticipated location of said person.

9. A system (2,41) as claimed in claim 1 or 2, wherein said at least one processor

(5,45) is configured to detect, based on said user input and/or detected using said one or more sensors, human presence in said area and determine an optical output pattern, a single light intensity, a sequence of light intensities, a light spectrum, and/or a duration of said light effect in dependence on said detected human presence.

10. A system (2,41) as claimed in claim 1 or 2, wherein said at least one processor

(5,45) is configured to control a first one of said set of light sources (11-13) to render said light effect in at least a first light spectrum at a first light intensity according to a first optical output pattern and control a second one of said set of light sources (11-13) to render said light effect in at least a second light spectrum at a second light intensity according to a second optical output pattern, wherein said second light spectrum is different from said first light spectrum, said second light intensity is different from said first light intensity, and/or said second optical output pattern is different from said first optical output pattern.

11. A system (2,41) as claimed in claim 1 or 2, wherein said at least one processor

(5,45) is configured to determine, based on said user input and/or detected using said one or more sensors, one or more characteristics of a surface (99) in said area and determine said need, a light intensity for said light effect, a light spectrum for said light effect, and/or a duration of said second light effect based on said one or more characteristics.

12. A system (2,41) as claimed in claim 11, wherein said one or more characteristics of said surface (99) comprise surface material, surface texture, surface reflectivity, water absorbance of the surface material, thickness of water film on said surface, volume of water on said surface, distribution of water on said surface, amount of soil in water on said surface, thermal conductivity of said surface, amount of dust on said surface, and/or amount of clutter on said surface.

13. A method of controlling a set of one or more light sources of a lighting device to provide disinfectant lighting for humid spaces in a building, said method comprising:

- determining (105) a need for disinfectant lighting in an area; - determining, based on user input and/or detected using one or more sensors, a humidity in said area, a humidity of an object in said area, or a thickness of a water film on a surface in said area;

- determining a duration of a first time period, during which at least one of said set of light sources is controlled to render a light effect comprising IR light, based on said humidity or said thickness of said water film; and

- controlling (109) said at least one of said set of light sources to render said light effect to provide said disinfectant lighting based on said need, said light effect comprising IR light during said first time period and UV light during a second time period, said second time period ending later than said first time period.

14. A computer program product for a computing device, the computer program product comprising computer program code to perform the method of claim 13 when the computer program product is run on a processing unit of the computing device.