Patent Publication Number: US-2019182926-A1

Title: Lighting device

Description:
TECHNICAL FIELD 
     The present invention is directed to a lighting device comprising a plurality of light emitting devices arranged in a two-dimensional array behind a translucent surface that prevents them from being directly visible and on which they render light effects by projection. 
     BACKGROUND 
     Luminous panels are a form of lighting device (luminaire) comprising a plurality of light emitting devices such as LEDs arranged in a two-dimensional array, placed behind (from an observer&#39;s perspective) an optically translucent surface which acts to “diffuse”, i.e. optically scatter, the light emitted from each individual LED. These panels allow for rendering of complex lighting effects (for example, rendering low resolution dynamic content) within a space and provide added value in the creation of light atmospheres and the perception of public environments whilst simultaneously illuminating the space. 
     The scattering is such that the light emitting devices are hidden, i.e. not directly visible through the surface. That is, their individual structure cannot be discerned by an observer looking at the surface. This provides an immersive experience, as the user sees only the light effects on the surface not the devices behind the surface that are rendering them. 
       FIG. 4A  shows a photograph of one such luminous panel, in which the optical effect of the translucent surface  208  is readily visible. Light effects  402  are projected onto the surface  208  from behind, by a two dimensional array of LEDs behind the surface that are not directly visible through it. 
     An example of a luminous panel is described at http://www.gloweindhoven.nL/en/glow-projects/glow-next/natural-elements which shows an installation in which natural elements like fire and water are generated by the luminous panel in an interactive manner. 
     The light emitting devices (such as LEDs) in the luminous panel are arranged to collectively emit not just any light but specifically illumination, i.e. light of a scale and intensity suitable for contributing to the illuminating of an environment occupied by one or more humans (so that the human occupants can see within the physical space as a consequence). In this context, the luminous panel is referred to as a “luminaire”, being suitable for providing illumination. 
     U.S. Pat. No. 8,042,961 B2 discloses a device that is a lamp on the one hand, and also a speaker on the other, comprising a light-emitting element, a surface that acts as a sound-emitting element, and a base socket that can fit to an ordinary household lamp socket. The surface can be translucent and act as a lamp cover at the same time. There is also an electronic assembly in the lamp that controls both the light-emitting and sound-emitting elements, as well as communicates with an external host or other devices. 
     SUMMARY 
     The present invention relates to a novel luminous panel, in which audio emitting devices, such as loudspeakers, are integrated along with the light emitting devices, such that the loudspeakers are also hidden behind the surface. The audio emitting devices are arranged such that audio effects (i.e. different and individually distinct sounds) can be emitted such that they are perceived to originate from desired locations on the surface. 
     Hence according to a first aspect disclosed herein, there is provided a lighting device comprising: a plurality of light emitting devices arranged in a two-dimensional array; a plurality of audio emitting devices co-located with the light emitting devices; and an optically translucent surface located forward of both the light emitting devices and the audio emitting devices such that the devices are not directly visible through the surface, wherein the surface is acoustically transparent such that sounds emitted from the audio emitting devices are audible through the surface; wherein the light emitting devices are controllable to render light effects at different locations on the surface, and the audio emitting devices are controllable to emit sounds perceived to originate from matching locations. 
     The light emitting devices and the audio emitting devices are located at predefined locations relative to the surface. Since there is a relation between the locations of the light emitting devices and the audio emitting devices, they can be controlled such that the sounds are perceived to originate from locations matching the light effects. 
     “Matching locations” means the same location or sufficiently nearby (e.g. behind the surface and the light effect) such that a user perceives the light effects themselves to be creating the sound. 
     Not only the light emitting devices but also the audio emitting devices are hidden by the translucent surface, therefore the user only sees the light effects, and the sounds are perceived to originate from the light effects themselves. This provides an enhanced immersive experience, but is not impacted by the presence of any visible loudspeakers. 
     A pair of stereo audio emitting devices behind the surface is sufficient for emitting sounds perceived from different locations, but only within a relatively narrow range of observation angles. 
     Particularly as luminous panels can be realized in large sizes, whereby the local light effects only cover part of the large surface individually, it can be desirable to co-locate rendered sound with the local light effects, for example. Note: a sound/audio effect being “collocated” with a light effect means the sound/audio effect is emitted such that it is perceived to originate from a location of the lighting effect. 
     In embodiments, the plurality of audio emitting devices is at least three audio devices. 
     In embodiments, the at least three audio emitting devices are arranged in a one-dimensional array. 
     In embodiments, the plurality of audio emitting devices is at least four audio emitting devices arranged in a two-dimensional array. 
     Preferably, the audio devices are arranged for emitting sounds from those locations using Wave Field Synthesis. As explained below, this allows the perceived matching of the audio and light effects to be perceived over a greater range of observation angles relative to the surface. 
     In embodiments, the plurality of light emitting devices is a plurality of light emitting diodes. 
     In embodiments, the optically translucent surface is a curved optically translucent surface. 
     According to a second aspect disclosed herein, there is provided a controller for controlling the lighting device according to the first aspect or any embodiments disclosed herein, the controller comprising: a location determining module configured to determine at least one location on the surface of the lighting device; a light controller configured to control the light emitting devices to render a light effect at the determined location on the surface; and an audio controller configured to control the audio emitting devices to emit a sound perceived to originate from the determined location whilst the light effect is being rendered, such that the sound is perceived to originate from the light effect. 
     In embodiments, the controller further comprises a sensor input configured to connect to at least one sensor, wherein the location on the surface is determined based on a location of at least one user detected by the at least one sensor. 
     In embodiments, the location determining module is configured to change the location on the surface such that the sound is perceived to originate from a moving light effect. 
     In embodiments, at least one characteristic of the light effect and/or the sound is varied based on a detected speed of the at least one user. 
     In embodiments, an intensity of the light effect increases as the speed of the at least one user increases. 
     In embodiments, a volume of the sound increases as the speed of the at least one user increases. 
     In embodiments, the audio controller is configured to control the audio emitting devices to emit the sound using Wave Field Synthesis. 
     According to another aspect disclosed herein, there is provided a system comprising the lighting device according to embodiments disclosed herein, and the controller according to embodiments disclosed herein. 
     According to another aspect disclosed herein, there is provided a lighting device according to embodiments disclosed herein, the lighting device comprising the controller embodiments disclosed herein. 
     According to another aspect disclosed herein, there is provided a method of controlling the lighting device of the first, the method comprising: determining at least one location on the surface of the lighting device; controlling the light emitting devices to render a light effect at the determined location on the surface; and controlling the audio emitting devices to emit a sound perceived to originate from a matching location whilst the light effect is being rendered, such that the sound is perceived to originate from the light effect. 
     According to another aspect disclosed herein, there is provided a computer program product for controlling the lighting device of the first aspect, the computer program product comprising code embodied on a computer-readable storage medium and configured so as when run on one or more processing units to perform operation of: determining at least one location on the surface of the lighting device; controlling the light emitting devices to render a light effect at the determined location on the surface; and controlling the audio emitting devices to emit a sound perceived to originate from a matching location whilst the light effect is being rendered, such that the sound is perceived to originate from the light effect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To assist understanding of the present disclosure and to show how embodiments may be put into effect, reference is made by way of example to the accompanying drawings in which: 
         FIG. 1  shows the structure of a lighting device in accordance with embodiments of the present invention. 
         FIG. 2  is an example of wave field synthesis in a room; 
         FIGS. 3A and 3B  show an example luminaire panel comprising light emitting devices co-located with a two-dimensional audio array in accordance with an embodiment of the present invention; 
         FIGS. 3C and 3D  show another example luminaire panel comprising light emitting devices co-located with a one-dimensional audio array in accordance with an embodiment of the present invention. 
         FIG. 4A  is a photograph of a luminous panel rendering light effects. 
         FIG. 4B  shows additional examples of lighting effects rendered by a luminous panel; 
         FIG. 5  is a schematic block diagram of a system according to embodiments of the present invention; 
         FIG. 6  shows an audio-visual effect comprising a lighting effect and a co-located audio effect; 
         FIG. 7  illustrates a scenario in which multiple observers are present; 
         FIGS. 8A and 8B  give an example of an audio-visual effect which dynamically responds to the location of a user. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A luminous panel comprises a large luminous surface and a light emitting device array (e.g. an LED array) covered by a surface which is an optically translucent and acoustically transparent surface, such as a textile diffusing layer. The invention comprises a luminous panel with an integrated loudspeaker array able to localize the rendered sounds based on the position of the local lighting patterns (and optionally the user position). That is, an array or matrix of audio speakers is integrated into the device. Light effects are enriched with audio, having the same spatial relation. The audio generation preferably makes use of the Wave Field Synthesis principle, so virtual audio sources can be defined and located with the light effects over a large range of observation angles. Preferably, to reduce sound pollution, the presence of people is detected and audio is directed towards the detected persons. 
       FIG. 1  shows the overall structure of a lighting device  200  according to an embodiment of the present invention, which is a luminous panel. The luminous panel  200  comprises an array of audio emitting devices  202 , an array of light emitting devices  206  and an optically translucent surface  208 . The array of audio emitting devices  202  and the array of light emitting devices  206  collocated with each other are placed on the same side of the optically translucent surface  208 , preferably with the array of light emitting devices  206  being placed between the optically translucent surface  208  and the array of audio emitting devices  202 . Therefore neither the audio or light emitting devices  202 ,  206  are visible from through the surface  208 . 
     The light emitting devices  206  and the audio emitting devices  202  are located at predefined locations relative to the surface  208 . Since there is a relation between the locations of the light emitting devices  206  and the audio emitting devices  202 , they can be controlled such that the sounds are perceived to originate from locations matching the light effects. For example, when a light effect is created by one or more light emitting devices  206 , the location of the light effect on the surface is known because of the predefined location of the one or more light emitting devices  206  relative to the surface. The audio emitting devices  202  also have a predefined location relative to the surface, so they can be controlled such that the sounds are perceived to originate from locations matching the light effects. The surface  208  has a large area, e.g. at least 1 m 2 . For example, it may be at least 1 m×1 m along its width and height. 
     The surface  208  can for example be formed of a textile layer, or any other translucent (but non-transparent) surface. 
     The surface  208  may be a flat surface or may be curved. For example, the surface  208  may be a concave curve shape or a convex curve shape across its width or height, from the point of view of an observer. 
     Each audio emitting device in the array  202  may be a loudspeaker. The luminous surface  208  is acoustically transparent such that sound generated by the audio array  202  behind the surface  208  can be heard by the user  110  without any significant audible distortion. The light emitting devices  206  also do not substantially interfere with sounds generated by the audio array  202 . 
     The light sources  206  are arranged in a two-dimensional array, and are capable of collectively illuminating a space (such as room  102  in  FIG. 2 , described later). Each comprises at least one illumination source, which can be any suitable illumination source, for example an LED, fluorescent bulb, or incandescent bulb. The plurality of light emitting devices  206  may comprise more than one type of illumination source. Each illumination source may be capable of rendering different lighting effects. In the simplest case, each illumination source is able to be in either an “on” or an “off” state. In more complex embodiments, each illumination source may be dimmable, and/or may be able to render different colours, hues, brightnesses and/or saturations. In any case, it is appreciated that the plurality of light emitting devices  206  arranged in an array such as those shown in  FIGS. 3A and 3B  is able to render lighting effects on the surface  208 , by projecting light onto the rear of the surface that is visible through the front after scattering from the surface  208 . 
       FIGS. 3A and 3B  show front and side cross-sectional views, respectively, the lighting device  200  configured according to a first embodiment of the present invention. Line A shown in the figures indicates the line of cross-section and represents the same line in each figure. That is,  FIG. 3B  shows the arrangement of  FIG. 3A  rotated ninety degrees about line A, and vice-versa, where the cross-section is taken along line A. 
     In the first example, there are at least four audio devices (possibly more) arranged in a two-dimensional array. 
     The speakers  202  are shown by dotted lines in  FIG. 3A  to indicate that they are behind the light sources  206 . The speaker array  202  uses audio wave field synthesis (WFS) to direct the audio from virtual audio sources to one or more observers as described in further detail below. The virtual audio sources are aligned with the rendered light effects. 
     The array of audio devices spans substantially all of the width and height of the array of light emitting devices, such that the audio devices at the four corners of the audio device array are collocate with the light emitting devices at the far corners of the light emitting device array. 
       FIGS. 3C and 3D  show front and side views, respectively, of a lighting device  200  configured according to another embodiment of the present invention. Unlike the arrangement shown in  FIGS. 3A and 3B , in this embodiment the plurality of speakers  202  are arranged in a one-dimensional array, or line. The array of audio devices spans substantially all the width of the array of light emitting devices, and runs horizontally across it. There are at least three audio emitting devices  202  in the array. 
       FIG. 4A  shows a photograph of a real-world luminous panel. The figure shows two users  404 ,  406  stood in front of a luminous panel. The luminous panel is rendering light effects  402  on the surface  208 . As can be seen, the light from individual light sources is scattered by the translucent surface  208  placed between them and the users. A loudspeaker array can be located behind the surface  208  in accordance with embodiments of the present invention. Neither array is visible in  FIG. 4A  because they are behind the surface  208 . 
       FIG. 4B  shows an example of more complex light effects rendered by the luminous panel on the surface  208 . The effects include a firework effect  300 , a fire effect  302 , three small star effects  304   a ,  304   b ,  304   c , and one large start effect  306 . In the present invention, a virtual audio source is generated for each light effect by the speaker array. The distance of the virtual audio source can be very large, so the audio effect will be rather small. 
       FIG. 5  shows a schematic overview of a system  500  according to embodiments of the present invention. The system  500  comprises a controller  502 , an audio array  202 , a luminous panel  204 , and optionally a sensor  506 . The audio array  202  and the luminous panel are arranged with the audio array  202  behind the luminous panel as seen by a user  110 . That is, the audio array  202  and luminous panel are placed within an environment such as room  102  such that the luminous panel is arranged to create lighting effects within the room  102  which are viewable by user  110 . 
     The controller  502  is operatively coupled to and arranged to control both the audio array  202  and the luminous panel  204 . The controller  502  is shown in  FIG. 5  as a separate schematic block but it is appreciated that the controller  502  may be implemented within another entity of the system such as within audio array  202  or luminous panel. Similarly, controller  502  is shown as a single entity but it is appreciated that controller  502  may be implemented in a distributed fashion as distributed code executed on one or more processors or microcontrollers. The processors or microcontrollers may be implemented in different system entities. The controller  502  comprises separate audio control module  502   a  and lighting control module  502   b  providing audio control and lighting control functionality, respectively. In this case it may be preferable to implement the audio control module in the audio array  202  and the lighting control module in the luminous panel. 
     As explained in detail below, the controller  400  determines a location on the surface, controls the light emitting devices  206  to render a light effect at that location (by audio controller  502   a ), and controls the audio emitting devices  202  to emit a sound perceived to originate from substantially that location, i.e. the same or a nearby location (e.g. slightly behind the surface). 
     The controller  502  can be integrated in the panel  200  itself, or it may be external to it (or part may be integrated and part may be external). 
     The controller  502  is connected to the audio array  202  and the luminous panel either directly by a wired or wireless connection, or indirectly via a network such as the internet. In operation, the controller  502  is arranged to control both the audio array  202  and the luminous panel via the connection. Hence it is appreciated that the controller  502  is able to control the individual audio devices and illumination sources to render lighting effects in the room  102 . To do so, the controller receives or fetches data  504  relating to a lighting effect to be rendered. The data  504  may be retrieved from a memory such as a memory local to the controller  502  where the data are stored, or a memory external from the controller  502  such as a server accessible over the internet as is known in the art. Alternatively, the data  504  may be provided to the controller  502  by a user such as user  110 . In this case the user  110  may use a user device (not shown) such as a smart phone to send the data  504  to the controller via a network, as is known in the art. 
     The system  500  optionally further comprises a sensor  506  operatively coupled to the controller  502  and arranged to detect the location of the user  110  within the environment  102 . Any suitable sensor type may be used provided it is capable of determining an indication of the location of the user  110  within the environment  102 . Hence, it is appreciated that while the sensor  506  is shown in  FIG. 5  as a single entity, the sensor  506  may comprise multiple sensing units. For example, the sensor  506  may consist of a plurality of signalling beacons preferably placed throughout the environment  102  which communicate with a user device of the user  110  and using, for example, received signal strength indication (RSSI), trilateration, multilateration, time of flight (ToF) etc. to determine the location of the user device e.g. using network-centric, device-centric, or hybrid approaches known in the art. The determined location of the user device can then be used as an approximation of the location of the user  110 . Other sensor types may not require the user  110  to have a user device. For example, passive infrared (PIR) sensors or ultrasonic sensors, or a plurality thereof. Another possibility is for the sensor  506  to be one or more cameras (which may or may not be visible wavelength cameras) to track the location of the user  110  within the environment  102 . An approximate location of the user may be sufficient. Whatever sensor type used, the sensor  506  is arranged to provide an indication of the user&#39;s location to the controller  502 . This location indication is used by the controller  502  in rendering audio-visual effects, as explained in more detail below. 
       FIG. 6  shows a luminous panel and audio array  202  according to embodiments of the present invention. In  FIG. 6 , the luminous panel is rendering a lighting effect at lighting effect location  604 , for example a fire effect such as fire effect  402  shown in  FIG. 4 . Simultaneously, the audio array  202  is rendering an audio effect at a virtual source location  602 . Note that the virtual audio source is not confined to being located at a physical location on the luminous panel (i.e. the virtual audio source does not have to be in the same physical location as the actual rendering of the light effect). Rather, the virtual audio source can be placed behind, or indeed even in front, of the speaker array and hence also behind or in front of the luminous panel. The audio effect is preferably semantically related to the lighting effect, for example the audio effect might be a fire sound to accompany fire effect  402 . The audio effect and lighting effect together may be collectively referred to as an audio-visual effect. 
     Audio devices such as speakers are available for rendering audio effects in a space. Known techniques such as stereo sound allow for spatialization of audio effects. That is, rendering the audio effect in a direction-dependant way. Surround sound and/or stereo speaker pair systems such as used in home entertainment systems can create an audio effect for a user in the space which is perceived to originate from a particular location. However, this effect is only properly rendered within a relatively small location, or “sweet spot”. In preferred embodiments of the present invention, the audio effects are created using Wave Field Synthesis (WFS) which allows for lighting effects rendered on a luminous panel to be accompanied by audio effects in a manner which does not confine an observer to a sweet spot in order to experience the combined audio-visual effect. 
     The audio controller  502  controls the array of audio sources  202  based on WFS to direct the audio from virtual audio sources to one or more users. The virtual audio sources are aligned with visual light effects rendered on the panel such that audio effects are perceived to originate from the rendered lighting effects. Preferably, the system also comprises a sensor for detecting the location of the user(s) in order to render the audio and visual lighting effects in an interactive manner. 
     WFS is a spatial audio rendering technique in which an “artificial” wave front is produced by a plurality of audio devices such as a one- or two-dimensional array of speakers. WFS is a known technique in producing audio signals, so only a brief explanation is given here. The basic approach can be understood by considering recording real-world audio sources (e.g. in a sound or concert) with an array of microphones. In the reproduction of the sound, an array of speakers is used to generate the same sound pattern as expected at the location of the microphone array, reproducing the location of the recorded sound sources from the perspective of a listener. However, a recording is not required, as similar effects can be synthesized. 
     The Huygens-Fresnel principle states that any wave front can be decomposed into a superposition of elementary spherical waves. In WFS, the plurality of audio devices each output the particular spherical wave required to generate the desired artificial wave front. The generated wave front is artificial in the sense that it appears to emanate from a virtual source location which is not (necessarily) co-located with any of the plurality of audio devices. An observer listening to the artificial wave front would hear the sound as though coming from the virtual source location. In this way, the observer is substantially unable to differentiate between the artificial wave front and an “authentic” wave front from the location as the virtual source based on sound alone. 
     Contrary to traditional techniques such as stereo or surround sound, the localization of virtual sources in WFS does not depend on or change with the listener&#39;s position. With a stereo speaker set, the illusion of sound coming from multiple directions can be created, but this effect can only be perceived in a rather small area between the speakers. Elsewhere, one of the speakers will dominate, especially when there is a big difference in distances between the speakers and the observer. 
       FIG. 2  illustrates the principles of WFS. The array of audio emitting devices  206  is disposed in a room  102 . The audio devices  206  are not shown individually in  FIG. 2  but the array is shown as a single element  100 . Each speaker in the array  100  outputs a respective spherical wave front (see for example wave front  104 ) which combine to produce a synthesized wave front  106 . The plurality of spherical wave fronts is such that the combined wave front  106  appears to originate from a virtual source  108  in that it approximates the “real” wave front which would have arisen had a real-world audio source been physically placed at the location of the virtual source  108 . 
     The spherical wave fronts can be determined by capturing a (real-world) sound with an array of microphones, or by purely computational methods known in the art. In any case, an observer  110  experiences the sound as though originating from the location of the virtual source  108 . 
     Note that the example in  FIG. 2  is shown only in two dimensions, but the principles of WFS extend to three dimensions when applied to the two-dimensional array of  FIG. 3A . That is, WFS can be applied both to the one-dimensional audio array of  FIG. 2A  and the two-dimensional audio array of  FIG. 2C . 
     Using WFS, it is generally possible to locate the virtual audio source  108  at a desired location not only in the plane of the surface  208  (x,y) plane, but also at different depths relative to the surface  208  (z-direction). Although light effects are rendered on the screen  208 , their virtual location might be behind the screen (e.g. fireworks). In these cases it is desirable to locate the virtual audio source as having some distance behind the screen. However, in practice it may be sufficient to just locate the virtual audio source  108  on the surface  208  (z=0). 
     As can be seen in  FIG. 6 , the audio effect and the lighting effect are spatially correlated insofar as they both appear to be originating from the same point on the surface  208 . Note that this correlation is observed by users from any location within the room. For example, a user at location  610  observes the audio effect and lighting effect as coming from the same direction, as does a user at location  612 . 
     In the situation shown in  FIG. 7 , two observers are in front of the panel. The light part generates a fire effect at ground level, in between the observers. The position of the observers is tracked and the location of this fire can depend on the location of the observers. A virtual audio source is created at the location of the fire effect. 
     The audio effect coming from a few speakers is too distributed, so also the sound might cause an audio pollution in the environment. To reduce pollution, the presence of people is tracked and virtual audio absorbers are placed between the virtual audio source and the empty areas in front of the panel. The virtual acoustic sources are used in the WFS. A virtual acoustic absorber is derived from this and indicates where sound effects should be actively cancelled. The controller  502  implements the WFS by calculating the wave field at the location of each speaker in the audio array  202  and deriving the signal for individual speakers to generate such a field. 
     The concept of virtual audio absorbers is derived from virtual audio sources and wave field synthesis. When implementing WFS by recording a (real) sound source using an array of microphones, real absorbers are placed in between the microphones and sources. The recorded audio is thus damped for some microphones behind the absorbers. When going to sound synthesis (WFS output by the audio array), the speakers that correspond to microphones which were behind the virtual absorbers at the recording stage, should also actively damp/mute the sound (like in noise cancellation). Hence, with virtual audio absorbers some speakers are actively reducing the sound to locations where no people are present. 
     It is also the intention to have some depth in the virtual sources. Although the light effect rendering is on the screen, the virtual source might be behind, as e.g. with fireworks. The use of virtual audio absorbers is in this case particularly useful when rendering sounds. This is because a virtual audio source which is aligned with a virtual light effect source (i.e. where the light effect is perceived to originate from) may be behind the translucent surface and hence not entirely aligned with the rendering location of the light effect itself. This may mean that two observers within the environment perceive a mismatch between the perceived location of the audio and light effect. It is clear that the observers will see some light effect in between them and on the screen while the audio seems further away 
     To compensate for this, when an effect is rendered for two observers, the confusion is minimized by directing the audio to a narrower location using virtual audio absorbers, having larger light effects, and having distant effects like fireworks (even with a delay between light and sound), or a combination thereof. 
       FIGS. 8A and 8B  show an embodiment in which an audio-visual effect dynamically responds to the location of the user  110 . The audio-visual effect comprises a lighting effect component  702  and a co-located audio effect component  704 . In  FIG. 8A , the controller  502  is controlling the luminous panel and audio array  202  to render the audio-visual effect directly in front of the user  110 , i.e. at the closest point to the user  110  on the surface but it is appreciated that the audio-visual effect may be rendered at any other point on the surface relative to the user  110 . The user&#39;s position is measured by the sensor  506  and provided to the controller  502  in determining the respective locations for the lighting effect  702  and the virtual source location of the audio effect  704 . 
     Readings from the sensor  506 , as provided to the controller  502 , can also be used by the controller  502  in a dynamic way. That is, the controller  502  is able to update the location of the audio-visual effect in response to a changing user location. For example, if the user  110  moves as shown by the arrow in  FIG. 8A  to the location shown in  FIG. 8B , the controller  502  is able to track the user&#39;s location using data from the sensor  506  in order to dynamically render the audio-visual effect to follow the user  110  as he moves within the environment. As can be seen from  FIGS. 8A and 8B , the audio-visual effect is able to maintain a constant heading relative to the user  110  as he moves. It is further appreciated that location data from the sensor  506  may also be used by the controller  502  to create other dynamic effects such as moving the audio-visual effect in the opposite direction to the user&#39;s motion. 
     However, as shown in  FIGS. 8A and 8B , when the user  110  is moving in front of the screen, the lighting effect and associated virtual audio source are moving together with the detected user  110 . This effect is advantageous, for example, in a public setting where it may be used to inform people that they have been observed (detected by the system) and trigger them either implicitly or explicitly via a visual or audio indication through the luminous panel or audio array to go into interaction with the audio-visual effect. 
     Location data of the user  110  may be used by the controller  502  to create move complex interactions. For example, the controller  502  may be able to determine the speed of the user&#39;s motion from time stamps of the sensor readings, as known in the art. In this case the controller  502  may create audio-visual effects in which one or both of the visual or audio components depend on the speed of the user. For example, a fast movement of the user  110  may result in a fire audio effect which is louder, or a fire visual effect which is brighter or larger on the panel. 
     It will be appreciated that the above embodiments have been described only by way of example. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. 
     For instance, simply co-locating the local audio effect with a local light effect without any advanced direction audio rendering or user position detection. 
     As another example, in an alternate and somewhat simpler embodiment as an alternative to WFS, the luminous panel may have a large number of light sources  206  similar to embodiments described above, but only a limited number of loudspeakers in a number of segments. The speaker array  202  could be segmented based on the number and position of the loudspeakers, (e.g.  4  or  9  loudspeakers arranged in a square). The luminous panel has means to keep track of the approximate position (segment) of each local light effect being rendered, including the sound effects associated with it. It then renders those sounds on the loudspeakers which correspond with the segment(s) where the local light effect is present. That is, the controller  502  determines which segment the lighting effect is currently being rendered in and controls the speakers in that segment to render the audio effect. Optionally, the audio rendering is done on multiple loudspeakers whereby the volume depends on the contribution of the local light effect in the corresponding loudspeaker segment. 
     In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.