IPC分类号：
F21V11/14 | F21V3/00 | F21V11/16 | F21Y115/10 | F21Y107/60 | F21Y113/13 | F21Y107/90
国民经济行业分类号：
C4350 | C3874 | C4090 | C3879
当前申请(专利权)人：
SIGNIFY HOLDING B.V.
原始申请(专利权)人：
PHILIPS LIGHTING HOLDING B.V.
当前申请(专利权)人地址：
HIGH TECH CAMPUS 48, 5656 AE, EINDHOVEN, NETHERLANDS
发明人：
DIJKEN, DURANDUS KORNELIUS | TALGORN, ELISE CLAUDE VALENTINE | BOOIJ, SILVIA MARIA | THIJSSEN, JOHANNES MARIA
代理人：
PIOTROWSKI, DANIEL J.
摘要：
The invention provides a lighting device (12) configured to provide both functional lighting for illuminating a space, and simultaneously to present a spatially dynamic sparkling light display. The device comprises a chamber (14) containing one or more light sources (28). The light sources are arranged to direct light in the direction of a translucent surface portion (20), and in the direction of a plurality of light exit areas (32) delimited by the translucent surface portion. The light exit areas each have a higher transmittance than the surrounding surface portion.
技术问题语段：
The technical problem addressed in this patent text is the need for a compact and affordable lighting device that can create a true spatially dynamic sparkling light effect, while also providing a functional light source for lighting a space. The current solutions either require the light sources to be installed at a distance from the sparkling panel, or use expensive and heavy lead glass panels. The invention aims to overcome these limitations by using special features and mechanisms to achieve a true dynamic sparkling effect.
技术功效语段：
The patent describes a lighting device that creates the impression of multiple light sources that change in intensity and color across the device's position. This effect is achieved by using optical elements that block or absorb some of the light emitted by the primary sources. These elements direct the light of different colors and angles, resulting in a unique and interesting illumination.
权利要求：
1. A lighting device for simultaneously providing functional lighting for illuminating a space and for providing to an observer of the lighting device a spatially dynamic sparkling or glittering effect of the lighting device,
wherein the lighting device comprises an exposed outer surface and a plurality of primary light sources disposed within a chamber,
wherein the chamber has an internal surface arrangement including at least a first surface portion and an opposing second surface portion, the first surface portion being a mounting surface portion, each of the plurality of primary light sources comprising an LED that is mounted to the mounting surface portion, the second surface portion being translucent and delimiting a plurality of light exit areas having a higher transmittance than the second surface portion,
wherein the plurality of light exit areas comprises a first pattern of light exit areas, the plurality of primary light sources comprises a second pattern of primary light sources, the second pattern of primary light sources being different to the first pattern of light exit areas,
wherein the plurality of primary light sources is arranged to illuminate the plurality of light exit areas delimited by the translucent second surface portion in order to create a plurality of secondary light sources located on the exposed outer surface of the lighting device, each of the plurality of secondary light sources producing an anisotropic luminance effect on the exposed outer surface of the lighting device when the lighting device is viewed by the observer; and
wherein one or more internal surfaces of the chamber are at least partially reflective and optionally wherein said internal surfaces are bounding internal surfaces.
2. A lighting device as claimed in claim 1, wherein each of the LEDs and each of the light exit areas has a size that is smaller than a separation distance between any two neighboring LEDs, and wherein at least one of the first pattern of light exit areas and the second pattern of primary light sources is an irregular or semi-random pattern.
3. A lighting device as claimed in claim 1, further comprising one or more optical elements each arranged in optical communication with one or more of the plurality of light exit areas, wherein each optical element is adapted to absorb, deflect or refract a portion of the light incident at them.
4. A lighting device as claimed in claim 3, wherein each optical element is directly coupled to or is comprised by one or more of the plurality of light exit areas.
5. A lighting device for simultaneously providing functional lighting for illuminating a space and for providing to an observer of the lighting device a spatially dynamic sparkling or glittering effect of the lighting device,
wherein the lighting device comprises an exposed outer surface and a plurality of primary light sources disposed within a chamber,
wherein the chamber has an internal surface arrangement including at least a first surface portion and an opposing second surface portion, the first surface portion being a mounting surface portion, each of the plurality of primary light sources comprising an LED that is mounted to the mounting surface portion, the second surface portion being translucent and delimiting a plurality of light exit areas having a higher transmittance than the second surface portion,
wherein the plurality of light exit areas comprises a first pattern of light exit areas, the plurality of primary light sources comprises a second pattern of primary light sources, the second pattern of primary light sources being different to the first pattern of light exit areas,
wherein the plurality of primary light sources is arranged to illuminate the plurality of light exit areas delimited by the translucent second surface portion in order to create a plurality of secondary light sources located on the exposed outer surface of the lighting device, each of the plurality of secondary light sources producing an anisotropic luminance effect on the exposed outer surface of the lighting device when the lighting device is viewed by the observer;
wherein the plurality of primary light sources comprises at least a first subset of primary light sources and a second subset of primary light sources, the first subset of primary light sources being configured to emit light that is directly incident at one or more of the plurality of light exit areas, and the second subset of primary light sources being configured to emit light that is not directly incident at any of the plurality of light exit areas; and
wherein the output intensity of each of the first and second subsets of primary light sources is independently adjustable.
6. A lighting device as claimed in claim 5, wherein the lighting device further comprises a controller configured to adjust the output intensity of the first subset of primary light sources in dependence upon the output intensity of the second subset of primary light sources.
7. A lighting device as claimed in claim 1, wherein the lighting device further comprises a translucent front panel positioned directly opposing an exterior side of said translucent second surface portion, and a space in between the translucent front panel and the translucent second surface portion.
8. A lighting device as claimed in claim 7, wherein the space in between the translucent front panel and the translucent second surface portion is configured to receive and/or at least partially retain a light transmissive fluid.
9. A lighting device for simultaneously providing functional lighting for illuminating a space and for providing to an observer of the lighting device a spatially dynamic sparkling or glittering effect of the lighting device,
wherein the lighting device comprises an exposed outer surface and a plurality of primary light sources disposed within a chamber,
wherein the chamber has an internal surface arrangement including at least a first surface portion and an opposing second surface portion, the first surface portion being a mounting surface portion, each of the plurality of primary light sources comprising an LED that is mounted to the mounting surface portion, the second surface portion being translucent and delimiting a plurality of light exit areas having a higher transmittance than the second surface portion,
wherein the plurality of light exit areas comprises a first pattern of light exit areas, the plurality of primary light sources comprises a second pattern of primary light sources, the second pattern of primary light sources being different to the first pattern of light exit areas,
wherein the plurality of primary light sources is arranged to illuminate the plurality of light exit areas delimited by the translucent second surface portion in order to create a plurality of secondary light sources located on the exposed outer surface of the lighting device, each of the plurality of secondary light sources producing an anisotropic luminance effect on the exposed outer surface of the lighting device when the lighting device is viewed by the observer; and
wherein the plurality of primary light sources comprises a first set of primary light sources adapted to emit light of a first spectral composition, and a second set of primary light sources adapted to emit light of a second spectral composition, wherein the chamber is arranged to at least partially mix the light of the first spectral composition with that of the second spectral composition.
10. A lighting device as claimed in claim 9, further comprising one or more further optical elements together adapted to direct light emitted by the first set of primary light sources through the light exit areas at a first range of propagation angles, and to direct light emitted by the second set of primary light sources through the light exit areas at a second range of propagation angles, and wherein optionally the further optical elements comprise light blocking elements adapted to deflect or absorb at least a portion of the light emitted by the first and/or second sets of primary light sources.
11. A lighting device for simultaneously providing functional lighting for illuminating a space and for providing to an observer of the lighting device a spatially dynamic sparkling or glittering effect of the lighting device,
wherein the lighting device comprises an exposed outer surface and a plurality of primary light sources disposed within a chamber,
wherein the chamber has an internal surface arrangement including at least a first surface portion and an opposing second surface portion, the first surface portion being a mounting surface portion, each of the plurality of primary light sources comprising an LED that is mounted to the mounting surface portion, the second surface portion being translucent and delimiting a plurality of light exit areas having a higher transmittance than the second surface portion,
wherein the plurality of light exit areas comprises a first pattern of light exit areas, the plurality of primary light sources comprises a second pattern of primary light sources, the second pattern of primary light sources being different to the first pattern of light exit areas,
wherein the plurality of primary light sources is arranged to illuminate the plurality of light exit areas delimited by the translucent second surface portion in order to create a plurality of secondary light sources located on the exposed outer surface of the lighting device, each of the plurality of secondary light sources producing an anisotropic luminance effect on the exposed outer surface of the lighting device when the lighting device is viewed by the observer;
wherein the translucent second surface portion comprises one or more shaped opaque regions for patterning the light output from the lighting device and/or wherein the lighting device comprises a front panel element comprising one or more shaped opaque regions for patterning light output from the lighting device.
12. A lighting device as claimed in claim 1 wherein in use, the plurality of secondary light sources provides the exposed outer surface with a dynamic sparkling effect.
13. A lighting device as claimed in claim 1,
wherein each of the primary light sources has an optical axis;
wherein the light exit areas are provided by holes in the second surface portion; and,
wherein said holes are formed at angles that are non-parallel with the optical axes of the primary light sources.
技术领域：
[0002]The invention relates to a lighting device for providing functional lighting to illuminate a space. The lighting device is simultaneously configured to provide a visually appealing lighting effect, in particular, a dynamic sparkling or glittering effect. The lighting device can for example be used in a lighting display or installation.
BACKGROUND OF THE INVENTION
[0003]The natural world provides many examples of so called dynamic lighting effects, and these phenomena can, for the observer, be highly captivating and entrancing aesthetic experiences. Consider, for example, sunlight refracted by water droplets or reflected on the moving sea surface, erratic star light, or sunlight blocked sporadically by the moving leaves of a tree. One particularly striking and notable effect is that of sunlight reflecting from snow.
[0004]Lighting designers often seek to recreate this striking effect of dynamic lighting in time and space. Dynamic lighting in time is easily realized through individually addressing LEDs within an LED ensemble. Dynamic lighting in space—a variation in light intensity depending on the viewer position—is often achieved through the use of glittering particles, lead glass crystals, or, in more complex solutions, through mechanisms that spatially displace the LED or optics. The effect created by dynamic lighting in space is commonly called glittering, or sparkling.
[0005]Glittering as a decorative effect is frequently used in architecture and in interior design, to provide a high end finish to walls or ceilings. It is visually appealing, and can provide a sense of luxury or glamour. Most standardly, glittering is achieved by reflecting light onto specularly reflective particles or by transmitting light through lead glass crystals.
[0006]This is usually achieved through applying glittering particles or lead glass crystals onto a surface, and using the reflection of light which is emitted by light sources installed at a distance from the surface. In this case, however, the light source must be installed as a separate component, which is aesthetically invasive and more burdensome and complex to install.
[0007]An alternative solution is to install the lead glass crystals into a panel, and to mount the light source(s) directly onto the back of them. Here, the light source remains hidden and the whole apparatus can be provided in a single, unitary panel.
[0008]However, use of lead glass crystals to achieve sparkling is not ideal. The crystals are generally expensive and heavy, and mounting them into a panel in order to realize the solution described is far from trivial.
[0009]In GB2243223A is described an illumination device designed to simulate the night sky. The device comprises a lighting panel having a front plate comprising holes, and which contains a plurality of conventional light sources, arranged to direct light toward said front plate. Between each of the light sources is positioned a wing reflector element, these elements are provided in order to project a maximum amount of light possible through the apertures of the front plate. To an observer looking at the panel from outside, an effect is created similar to that of a starry night sky.
[0010]However, in this solution, the light sources remain visible through the apertures in the front plate over all angles. As a result, a true (spatially dynamic) sparkling effect, in which point sources across the display give the impression of disappearing and appearing briskly as one changes position, is not created.
[0011]Furthermore, it may be desirable to provide a sparkling effect in combination with conventional functional illumination for lighting the space within which the lighting device is placed. This allows the appealing aesthetic effect of spatially dynamic sparkling to be created in environments and scenarios where, for reasons of space or of aesthetics, it is not practical or desirable to provide both a lighting device for functional lighting in addition to a dedicated decorative unit for providing the sparkling effect. Such sparkling might also provide an appealing or desirable bonus feature to an otherwise predominantly functionally-targeted lighting product.
[0012]There is a need in the art therefore for a lighting device capable of creating a true spatially dynamic sparkling light effect, but which is more compact than solutions requiring light sources to be installed at a distance from a sparkling panel, and which is cheaper, lighter and simpler than alternative lead glass panel solutions, and which is further capable of providing a functional light source for lighting a space.
发明内容：
[0013]The invention is defined by the claims.
[0014]According to an aspect of the invention, there is provided a lighting device for simultaneously providing functional lighting for illuminating a space and a dynamic sparkling or glittering effect. The lighting device comprises an exposed outer surface and at least one primary light source disposed within a chamber. The chamber has an internal surface arrangement including at least a first surface portion and an opposing second surface portion, the at least one primary light source being located on the first surface portion. The second surface portion being translucent and delimiting a plurality of light exit areas having a higher transmittance than the second surface portion. The at least one primary light source is arranged to illuminate the plurality of light exit areas delimited by the translucent second surface portion in order to create a plurality of secondary light sources located on the exposed outer surface of the lighting device, each of the plurality of secondary light sources having a light-emitting surface with an anisotropic luminance.
[0015]In the context of the present invention, an exposed outer surface is a surface that is at the outside of the lighting device and that is directly observable by an observer. This means that when an observer is looking in a direction towards the exposed outer surface he can observe the exposed outer surface without the interference of any other component of the lighting device. Because the plurality of secondary light sources is located on the exposed outer surface of the lighting device, these secondary light sources are also directly observable by an observer. An observer looking in a direction towards the exposed outer surface can observe the light-emitting surface of each secondary light source without the interference of any other component of the lighting device.
[0016]Each of the plurality of secondary light sources has a light-emitting surface with an anisotropic luminance. The term “luminance” denotes the luminous intensity per unit area of light travelling in a given direction. The luminance indicates how much luminous power will be detected by an observer looking at the light-emitting surface from a particular angle of view. Luminance is thus an indicator of how bright the light-emitting surface will appear (the term “brightness” being typically used to refer to the subjective impression of luminance). When the luminance of a light-emitting surface is anisotropic, the apparent brightness of the light-emitting surface depends on the observer's angle of view.
[0017]In the context of the present invention, a light source can be a “real” light source or a “virtual” light source. The aforementioned secondary light sources that are created upon illumination of the light exit areas delimited by the translucent second surface portion are virtual light sources. The one or more primary light sources can be real or virtual light sources.
[0018]In operation, the aforementioned lighting device creates for an observer an effect of light sources that significantly diminish or alter in intensity or spectral composition across a range of different positions relative to the lighting device.
[0019]Each of the real or virtual primary light sources that is located on the first surface portion creates a plurality of virtual secondary light sources on the exposed outer surface of the lighting device. When looking at the exposed outer surface of the lighting device, and dependent on the position relative to the exposed outer surface, an observer will either have a direct line of sight with the primary light source that creates the plurality of secondary light sources, or no direct line of sight with the respective primary light source.
[0020]By providing a translucent surface portion in optical communication with at least one primary light source, said translucent surface portion delimiting or defining holes or other light exit areas, the device is capable of generating both a sparkling effect (by means of light exiting through the light exit areas within the surface portion) and a source of functional lighting (by means of light passing through the much broader and more expansive translucent surface portion).
[0021]For the sparkling effect, the plurality of secondary light sources created by a primary light source ideally emits light in alternately spaced angular ranges, being a plurality of angular ranges or angular distributions that are non-overlapping and also non-adjacent, or non-proximate. When an observer is within one of these alternately spaced angular ranges, he has a direct line of sight with the primary light source that creates the plurality of secondary light sources when he is looking in the direction of the lighting device. When the observer is not within one of these alternately spaced angular ranges, he has no direct line of sight with the respective primary light source.
[0022]In embodiments, there may be provided both a plurality of primary light sources, and a plurality of light exit areas, to thereby provide a more expansive and noticeable sparkling effect. The translucent second surface portion may extend across a broad region, for instance all or most of, a visible front surface of the lighting device for example.
[0023]Under such an arrangement, when a primary light source, light exit area and observer's eye are all in alignment, light emitted by the primary light source falls incident at the observer's eye, and he perceives, emanating from the position of the light exit area, a bright point or spark of light. If the observer moves his position slightly, such that said alignment is broken, at least a significant portion of the light from the respective primary light source ceases to fall incident at the observer's eye and the bright light spot gives the appearance of vanishing from view, or at least significantly diminishing in intensity. When replicated across the whole front surface of the device, an effect is created for an observer of almost instantaneously appearing and disappearing bright light sources, occurring across a wide range of different positions across the device, and set against a background illumination of an intensity more diminished than that exiting through the light exit areas. In this way, a true spatially dynamic sparkling light effect is created.
[0024]The sparkling effect thus described is visible against the background light provided through the translucent second surface portion by consequence of the fact that the transmissivity or transmittance of the light exit areas is in all cases higher than that of the translucent second surface portion delimiting them. Hence the ‘background’ light visible through the translucent second surface portion appears dimmer or less intense than light exiting through the light exit areas. This latter light hence stands out against the constant (functional) background illumination provided by the translucent surface, and the sparkling effect is apparent.
[0025]According to one or more embodiments, one or more internal surfaces of the chamber may be at least partially reflective and optionally said internal surfaces may be bounding internal surfaces. These surfaces may for example be white surfaces, and adapted therefore to reflect the entirety of the spectral composition of any light emitted by at the least one primary light source which falls incident at them. They may further be adapted to reflect all or only a portion of this light (i.e. to be fully or partially reflective).
[0026]In other examples, said internal surfaces may be adapted to reflect only a portion of the spectral composition of any light falling incident at them. They may for example be adapted to absorb or to only reflect spectral frequencies corresponding to particular visible colors of light. According to these examples, light exiting the chamber directly from the primary light source may have a different visible color to light exiting indirectly via reflection from said internal surfaces. These surfaces too may be either fully or partially reflective.
[0027]Further to this, in some examples, the translucent second surface portion may be adapted or configured, either independently or in combination with one or more additional optical elements to transmit only light of a particular range or selection of spectral frequencies, for example only light corresponding to a particular visible color. The translucent second surface portion may be colored or diffusive for instance, or a color filter or diffuser may be coupled or mounted to the interior or exterior of the second surface portion relative to the chamber.
[0028]In these or further examples, said internal surfaces may comprise specularly reflective surfaces such as mirrored surfaces.
[0029]According to one or more embodiments, the first surface portion of the chamber may be a mounting surface portion, wherein the at least one primary light source, for example a plurality of primary light sources, is mounted to said mounting surface portion.
[0030]In accordance with this example, the at least one primary light source may for example be a solid state light source, and the mounting portion may house or carry for instance a PCB for electrically mounting the solid state light source.
[0031]In one example for instance, the lighting device may comprise a panel or boxed-shaped lighting device, wherein the translucent second surface portion comprises or is comprised by a front panel element, and wherein the mounting surface portion comprises or is comprised by a rear panel element.
[0032]However, in accordance with other examples, the at least one primary light source may comprise for instance a conventional or LED retrofit light bulb, being electrically and mechanically coupled to a conventional light fitting. In this case, a dedicated mounting portion may not be required. However, in all cases, the at least one primary light source is arranged to illuminate the translucent second surface portion.
[0033]According to this or other examples, the translucent second surface portion may for instance at least partially define a spherical or elliptical shaped chamber which extends around or encloses the at least one primary light source. More generally, the translucent second surface portion may at least partially define a body which envelopes the chamber. This body may have a regular shape such as a spherical or elliptical shape or may have a free-form shape.
[0034]It is noted that in embodiments, the at least one primary light source may be arranged to illuminate said translucent second surface portion indirectly, for example in optical collaboration with one or more further elements, for instance one or more mirrors or other reflective elements or arrangements. The at least one primary light source is in all cases arranged and configured to be in optical communication with the translucent second surface portion, so that, whether directly or indirectly, it is arranged to illuminate the translucent second surface portion.
[0035]In order to provide suitably bright functional light, it may be necessary to configure or adjust the one or more primary light sources to emit light at an intensity or brightness which, were it permitted to pass unimpeded through the light exit areas, would be of a dangerous or at least uncomfortable brightness for an observer looking at the lighting device.
[0036]Accordingly, in accordance with one or more embodiments, the lighting device may further comprise one or more optical elements each arranged in optical communication with one or more of the plurality of light exit areas, wherein each optical element is adapted to absorb or deflect a portion of the light incident at them. The optical elements may be arranged for instance along one or more optical axes extending between one or more of the primary light sources and one or more of the light exit areas. In this way, light from the one or more primary light sources falls incident at said optical elements on its path toward the light exit areas. The effect of the optical elements may be to reduce the intensity or apparent brightness of the light exiting through the light exit areas, i.e. to reduce the total optical flux passing through one or more of the light exit areas.
[0037]In particular examples, the optical elements may comprise light filters, configured to absorb a portion of the light passing through them. In other examples, the elements may comprise semi-reflective elements, such as partial mirrors, adapted to reflect a portion of the light incident at them.
[0038]Each of said optical elements may in examples be directly coupled to or be comprised by one or more of the plurality of light exit areas.
[0039]In accordance with one or more embodiments, the one or more primary light sources is a plurality of primary light sources, said plurality of primary light sources comprising at least a first set of primary light sources and a second set of primary light sources, the first set of primary light sources being configured to emit light that is directly incident at one or more of the plurality of light exit areas, and the second set of primary light sources being configured to emit light that is not directly incident at any of the plurality of light exit areas. In examples, this may allow light delivered directly through the light exit areas to have differing optical properties to other light delivered directly to the translucent second surface panel or delivered only indirectly to the light exit areas. This may for instance enable a sufficiently high intensity or brightness of light to be emitted from the device as functional light, while avoiding the situation that any light directly emitted from a primary light source through a light exit area has an intensity which is uncomfortably or dangerously high. The first set of primary light sources may be configured to emit light which is dimmer, or appears dimmer, than the second set of primary light sources for instance.
[0040]In particular examples, the output intensity of each of the first and second sets of primary light sources may be independently adjustable. In this way the intensity of the functional light output might be increased for instance, without correspondingly increasing the intensity of light directly emitted through the light exit areas. Their respective output intensities may be adjustable while the device is in operation for instance. One or more of the output intensities may be adjustable by means of a user control element or user input element.
[0041]In some examples, the lighting device may further comprise a controller configured to adjust the output intensity of the first set of primary light sources in dependence upon the output intensity of the second set of primary light sources. The controller might for instance be configured to reduce the output intensity of the first set of primary light sources in response to increases in the output intensity of the second set of primary light sources.
[0042]According to these examples, the output intensity of the second set of primary light sources might be configured to be user defined or controlled for instance, so that the lighting device provides fully adjustable functional light output, while automatically adjusting the intensity of the sparkling effect, for instance to avoid dangerous or uncomfortable levels of radiant flux exiting any given light exit area.
[0043]In accordance with one or more embodiments, the lighting device may further comprise a translucent front panel positioned directly opposing an exterior side of said translucent second surface portion, and a space in between the translucent front panel and the translucent second surface portion.
[0044]In particular examples, said space may be configured to receive and/or at least partially retain a light transmissive fluid. Such an embodiment provides a particularly interesting and striking aesthetic effect, as light is emitted from the lighting device via the thus provided layer of fluid. In examples, said fluid may comprise smoke or another at least partially light transmissive gas or gas mixture.
[0045]According to one or more further examples, said same aesthetic effect may similarly be provided without the structural requirement of an additional front panel to contain the fluid. For example, the fluid may instead simply be continuously passed or transported across the exterior side of the translucent second surface portion, or directed at said exterior side, or wherein some other mechanical or structural feature enables a constant presence of fluid to be maintained across the front of the panel.
[0046]In accordance with such an example there may hence be provided a lighting device arrangement comprising a lighting device in accordance with any example embodiment described; and a fluid delivery means for projecting, propelling or transporting a light transmissive fluid in front of an exterior side of the translucent second surface portion.
[0047]The fluid delivery (or supply) means may in examples generate a fluid for propelling or transporting in front of the translucent second surface portion, or may be adapted to propel or deliver fluid already provided for example.
[0048]In one or more embodiments, the one or more primary light sources may each have a respective optical axis, and the light exit areas may be formed or arranged such that none lie on any of said respective optical axes. For example, the one or more primary light sources may be arranged at positions laterally displaced from the positions of the light exit areas, where laterally displaced means displaced in a direction parallel with the translucent second surface portion.
[0049]In this way the primary light sources may be arranged such that an observer looking directly through a light exit area is unable to see the arrangement or pattern of primary light sources disposed within the chamber. This adds to the overall aesthetic effect of the lighting device, which is to provide to an observer, on moving past the device, a sparkling effect which is surprising and mysterious, where the source of the glittering lights remains obscure.
[0050]In examples, the plurality of light exit areas may comprise a first pattern of light exit areas and the at least one primary light source is a plurality of primary light sources that comprises a second pattern of primary light sources, the second pattern of primary light sources being different to the first pattern of light exit areas, wherein at least one of the first pattern of light exit areas and the second pattern of primary light sources optionally is an irregular or semi-random pattern. In this way, the light exit areas and the primary light sources may be respectively arranged so as to not align or coincide with one another, thereby helping to keep the arrangement of primary light sources hidden from an observer.
[0051]By utilising an irregular or semi-random pattern, greater freedom is afforded in the arrangement or configuration of the light exit areas, since these may (theoretically) be configured according to any desired pattern, while substantially avoiding alignment with the primary light sources.
[0052]In accordance with one or more embodiments, the at least one primary light source may comprise a first set of primary light sources adapted to emit light of a first spectral composition, and a second set of primary light sources adapted to emit light of a second spectral composition, wherein the chamber is arranged to at least partially mix the light of the first spectral composition with that of the second spectral composition.
[0053]A spectral composition of light may refer to a spectral profile of the light, meaning the composition of component frequencies of radiation which form the light. In examples, the light may have a spectral composition which comprises one or more frequency components falling outside of the visible spectrum. In some cases, spectral composition may imply a particular color of light, or may imply light that is a combination of colors, such as white light of a particular color temperature.
[0054]Hence according to these embodiments, the lighting device may be adapted to emit light of different colors. In particular, the lighting device may be configured to emit directly via one or more of the light exit areas light of just a first and/or second spectral composition for instance, while being configured also to emit via the translucent second surface portion and/or one or more light exit areas light comprising a mix of both the first and second spectral compositions. The mixed light may constitute a functional light for illuminating a space for instance, while the directly emitted light of just the first or second spectral composition may form all or part of the sparkling effect appearing on top of the background functional light for example.
[0055]In one or more particular examples, the plurality of primary light sources may comprise a first set of primary light sources adapted to emit red light, a second set of primary light sources adapted to emit green light and a third set of primary light sources adapted to emit blue light. The chamber according to this example is configured to mix the light of all three sets, thereby generating a white light source which is emitted from the device at a range of propagation angles via the translucent second surface portion and also possibly the light exit areas. In addition, each of the first, second and third sets of primary light sources may be arranged within the chamber to emit light directly toward one or more of the light exit areas, so as to allow direct exit from the chamber light of just a single one of the three colors. These directly emitted rays or beams may form red, green and/or blue sparkling effects, visible against an apparently white background (functional) light.
[0056]In certain examples, the first set of primary light sources may be arranged to emit light directly incident at the light exit areas and the second set of primary light sources may be arranged so as only to only deliver light to the translucent second surface portion. In this way, the functional light may be provided having a different color to the sparkling effect.
[0057]According to one set of examples of these embodiments, the lighting device may further comprise further optical elements together adapted to direct light emitted by the first set of primary light sources through the light exit areas of the translucent second surface portion at a first range of propagation angles, and to direct light emitted by the second set of primary light sources through the light exit areas at a second range of propagation angles, and wherein optionally the further optical elements comprise light blocking elements adapted to deflect or absorb at least a portion of the light emitted by the first and/or second sets of primary light sources.
[0058]In these examples, an observer may observe light of a first color when looking at the device from a first range of angles relative to the device, and may perceive light of a different color when looking from a second range of angles relative to the device. When an observer changes his position relative to the device, he may observe the first color when moving and facing in a first set of directions relative to the device, and may observe the second color when moving and facing in a second set of directions relative to the device.
[0059]In some examples of the above embodiment, the further optical elements may comprise light blocking elements adapted to deflect or absorb at least a portion of the light emitted by the first and/or second sets of primary light sources. These elements together provide the effect of directing light of the first spectral composition through light exit areas across the first range of propagation angles, and directing light of the second composition across the second range of angles.
[0060]Additionally or alternatively, in some examples the first set of primary light sources may be arranged at a first distance from the translucent second surface portion, and the second set of primary light sources may be arranged at a second distance from the translucent second surface portion, wherein the optical elements are disposed in-between the first set of primary light sources and the second set of primary light sources.
[0061]In this case, the first range of angles may comprise the second (or vice versa), i.e. the second range lies within the first. Here, the set closer to the light exit areas may emit light across the broader first range of angles, and the furthermost set, may emit light which, by means of the optical elements, is directed through the light exit areas only across a narrower range of angles. The effect of this is that over said narrower range of angles, an observer may perceive light of two different colors (corresponding to both the first and second spectral compositions), and over the remaining angles, may perceive light only of the second or first color.
[0062]In any of the above examples, the primary light sources may alternatively comprise more than two sets of spectrally differing primary light sources, for example three or more sets of primary light sources, each set comprising sources adapted to emit light having a spectral composition different from the other sets.
[0063]Furthermore, in examples of the above or any other embodiment, one or more of the primary light sources may be adapted to individually emit light having a first spectral composition across a first range of propagation angles, and to emit light having a second spectral composition across a second range of propagation angles. Alternatively, said one or more primary light sources may not emit the different spectral compositions at different angles, but may simply be adapted to emit light of the first composition across a first portion of a light emitting surface and light of the second composition across a second portion of a light emitting surface. The different spectral compositions may imply light of differing colors. In either of the above cases, said one or more of the primary light sources may be adapted to emit light exhibiting a color gradient.
[0064]In particular examples, one or more of the primary light sources may comprise a single light emitting element adapted to emit light of more than one color, or may comprise a light source having multiple individual elements configured to operate co-operatively to produce light of more than a single color. In either case, these multiple colors may be generated singly (in isolation), or simultaneously with one another. In certain examples, one or more of the primary light sources may comprise an RGB LED and/or may comprise a co-operative assembly of one or more of each of a red LED die, a green LED die and a blue LED die. In examples, the intensity of each LED die or light source may be individually adjustable and/or each individual LED of a multiple LED light source (for instance) may be individually addressable.
[0065]According to one or more embodiment, the translucent second surface portion may comprise one or more shaped opaque regions for patterning the light output from the lighting device and/or the lighting device may comprise a front panel element comprising one or more shaped opaque regions for patterning light output from the lighting device.
[0066]The opaque regions may be shaped for instance so as to pattern the light in the form of symbols, letters or numerals for example. Such an embodiment might for instance be advantageously applied within a signage application, where it may be desired to pattern the output light (or shape the opaque regions) so as to communicate information or messages to an observer.
具体实施方式：
[0090]The invention provides a lighting device configured to provide both functional lighting for illuminating a space, and simultaneously to present a spatially dynamic sparkling light display.
[0091]The device comprises an exposed outer surface and a chamber containing one or more primary light sources. The chamber has an internal surface arrangement including at least a first surface portion and an opposing translucent second surface portion, wherein the at least one primary light source is located on the first surface portion. The one or more primary light sources are arranged to direct light in the direction of the translucent second surface portion, and in the direction of a plurality of light exit areas delimited by the translucent second surface portion. The light exit areas each have a higher transmittance than the surrounding translucent second surface portion. This creates a plurality of secondary light sources located on the exposed outer surface of the lighting device, wherein each of the plurality of secondary light sources has a light-emitting surface with an anisotropic luminance.
[0092]Light incident at the translucent second surface portion is transmitted from the device at a higher level of attenuation than light incident at any of the light exit areas. The relative transmittance of the light exit areas and the surrounding translucent second surface portion is configured to ensure sufficiently high luminous contrast between the apparent intensity of a virtual secondary light source which is in alignment with a primary light source and an observer's eye, and the apparent luminosity of regions of the exposed outer surface of the device immediately surrounding the virtual secondary light source. This ensures that only when an observer's eye is in alignment with a respective light exit area and with a primary light source the primary light source is visible at its full intensity. As soon as this alignment breaks, the primary light source appears to the observer to vanish from view, or at least to significantly diminish or alter in intensity. It is this effect which provides the spatially dynamic glittering light effect.
[0093]FIG. 1 schematically illustrates a first example of a lighting device 12 in accordance with an embodiment of the present invention, which is demonstrative of the general concept of the invention embodied by all examples of the invention. The lighting device 12 comprises a panel or box shaped frame or structure whose interior comprises a chamber 14 which is bounded by a back panel 18, side panels (of which only two 22, 24 are shown in FIG. 1), and translucent front panel 20. The translucent front panel in accordance with this example is translucent across its full dimensions, and fully constitutes the translucent second surface portion for the purposes of the invention. The panel or box embodiment of FIG. 1 comprises six internal surfaces, which include the respective interior surfaces of each of: the back panel 18, the translucent front panel 20, first side panel 22, and second side panel 24 (plus two additional side panels, not shown). It is emphasized that this particular shape, having an internal surface arrangement comprising six surfaces is shown by way of example only, and other arrangements comprising for example a triangular or other polygonal shaped device may also be used.
[0094]A plurality of primary light sources 28 disposed within the chamber are located on a first surface portion, being a mounting surface portion 30, which forms a portion of the inner surface of back panel 18, i.e. the surface facing the chamber 14 by way of example only. In other examples, the primary light sources 28 may be provided, fixed or otherwise carried within the chamber 14 by any other suitable means. The primary light sources 28 are spatially separated from the translucent front panel 20 and are spatially separated from each other, such that the back panel 18 may comprise a plurality of point light sources spatially separated by dark areas, i.e. areas in which no light sources are present. Such distributed primary light sources 28 may generate the desired sparkling effect as will be explained in more detail below.
[0095]The primary light sources 28 are operable to emit light in a range of propagation angles in directions toward a plurality of light exit areas 32 formed at various locations through translucent front panel 20. The light exit areas 32 are configured having an optical transmittance which is greater than the surrounding translucent front panel 20 which defines or delimits them. As shown by arrow 34 in FIG. 1, light incident at a light exit area is transmitted directly through said light exit areas.
[0096]In operation, the primary light sources 28 illuminate the light exit areas 32 delimited by the translucent front panel 20. This creates a plurality of secondary light sources located on the outer surface of the front panel 20, being an exposed outer surface of the lighting device 12. Each of these secondary light sources coincides with one of the light exit areas 32, and each has a light-emitting surface with an anisotropic luminance.
[0097]The arrangement of a plurality of primary light sources 28 on a mounting portion 30 may be such that each primary light source is horizontally or laterally displaced from any light exit area 32 of the front panel 20. The effect of this is that an observer looking through a light exit area, in a direction of the optical axes of the primary light sources, is not able to observe the full arrangement of the primary light sources lying beneath. This adds to the interest and enjoyment of the resultant lighting device, since the mechanical workings providing the sparkling effect are not immediately apparent.
[0098]According to these or other examples, the primary light sources might be arranged according to a first regular pattern, and the light exit areas arranged according to a second different regular pattern. The patterns may differ in the pitch between neighboring primary light sources and/or light exit areas, or may differ simply in their relative alignment, so that the elements of the first pattern are arranged to interleave with the elements of the second pattern.
[0099]Alternatively, the light exit areas and/or the primary light sources may be arranged according to an irregular pattern, such as a random or semi-random pattern. The advantage of using such a pattern for one of either the light exit areas or the primary light sources is that this affords a degree of freedom in the arrangement of the other, since substantial non-alignment of primary light sources and light exit areas may be expected to follow automatically from the irregularity of the pattern used. For instance, by arranging the light exit areas (or window elements) semi-randomly, then this allows the primary light sources to be arranged according to a standard regular array configuration, which may be substantially cheaper and easier to manufacture.
[0100]By random or semi-random is meant a pattern or arrangement for example in which the separation distance, pitch or relative angular arrangement of subsequent or adjacent elements in the pattern (primary light sources or light exit areas) differs or varies in a non-regular way. In particular examples, the primary light sources and/or light exit areas may be arranged to follow a Voronoi-like pattern or arrangement.
[0101]The primary light sources 28 in some embodiments may be provided in a regular N×M array (in which M, N are positive integers), an irregular array, or may be positioned in an arbitrary arrangement.
[0102]In at least some embodiments, the primary light sources 28 may be, or may comprise, solid state light sources, such as LEDs. Use of LEDs provides for high energy efficiency and also relatively sharp directionality of emitted light. The primary light sources 28 may be provided mounted via a Metal Core Printed Circuit Board (MCPCB). Flip-chip LEDs may be provided mounted directly onto a PCB. Other suitable mounting arrangements of the primary light sources 28 will be immediately apparent.
[0103]As shown by arrows 35, light incident at the translucent front panel 20 is attenuated as it passes through the panel (to a greater extent than light passing through light exit areas 32), with the result that this light appears dimmer or less intense than light 34 emitted via the light exit areas. This light may provide a ‘background’ illumination suitable for lighting a space such as for example a room, while the light exiting directly via the light exit areas appear to an observer (whose eye is in the appropriate alignment with the respective light source) as bright spots of light superposed on top of the background illumination. These bright spots coming into and out of alignment as the observer moves create a spatially dynamic glittering or sparkling effect on top of a relatively dimmer background layer of illumination. The overall effect is comparable to the sparkling effect generated by snow illuminated by sunlight.
[0104]As noted, light transmitted from the device through the translucent front panel, may in accordance with example embodiments provide a source of functional illumination for illuminating a space. Accordingly, for this (or any other) embodiment, the plurality of primary light sources 28 may be arranged or adapted to produce white light, or configured to produce spectral components which may be mixed to form white light.
[0105]The light exit areas 32 may, by way of non-limiting example, constitute holes, or fully or partially light transmissive window elements formed for instance of a light transmissive material having an optical transmittance greater than that of the translucent front panel.
[0106]In example embodiments, the light exit areas 32 may be provided by holes formed at an angle (or different angles) through the translucent front panel 20 cardboard. By providing such holes aligned at angles non-parallel with optical axes of the primary light sources 28, the range of angles over which the sparkling light effect created by the device is visible to observers is accordingly restricted. This may be used in examples to direct the light effect to be visible only (or predominantly) at relatively narrow angles to the panel for instance, such that the panel is visible to observers far away from the panel, walking or positioned in relatively acute angles to the front of the lighting device. This may attract potential customers to the lighting panel from far distances away for instance.
[0107]Alternatively, the light exit areas may in some examples be formed simply by regions of the translucent front panel where the material is thinner than in the remainder of the panel.
[0108]The translucent front panel 20 may in examples comprise a translucent glass plate, having a layer of black (or other absorbing) paint applied to one side. The light exit areas may in this case be provided by non-painted areas of the glass plate, or areas where paint has been removed. A paint layer may be applied either to one side or to both sides of the glass plate.
[0109]According to one or more further non-limiting examples, the translucent front plate may comprise a transparent plate having a translucent layer printed (or in any other way provided or deposited) over one or both of the interior and exterior surface. Light exit areas may be provided by regions not covered with said layer, or regions where the layer has been subsequently removed. In particular examples, said translucent layer may be a white digital (inkjet) print layer. In one test, eight layers of white print provided a suitable degree of translucency. However, this is to be understood as exemplary only and it should be understood that the print layer may have any suitable thickness.
[0110]In certain examples, as in the case illustrated in FIG. 1, the translucent front panel may also act to partially diffuse the light transmitted through it, such that the light is spread or deflected across a range of outgoing propagation angles (shown by arrows 35). This may for example have the effect of giving the background functional light a Lambertian output profile.
[0111]Such partial diffusion also may act to further enhance the apparent contrast between light directly emitted via the light exit areas 32 and light emitted via the translucent front panel 20, since light emitted via the light exit areas 32 may have relatively greater directionality than light emitted via a diffusing front panel. This spreading of propagation angles, so as for example to generate a Lambertian output, may also help to improve the functionality of the light thus generated in illuminating a broad space.
[0112]In accordance with any embodiment of the invention, the translucent front panel may have any range of light transmittance. Light absorption by the translucent front panel 20 may range for example from 0.5% (high Q diffuser) to close to 100%. These numbers are provides purely by way of illustration and as will be understood by the skilled person, other specifications may alternatively be employed.
[0113]The optical efficiency of the system may vary depending upon the level of light output desired. For a soft glow-like functional light output, the efficiency may be as low as about 10%. However, for a more efficient functional light system, the system efficiency may be greater than 70%, for example 90%. Again, other specific technical constraints may equally be used, and these numbers are described by way of illustration only.
[0114]According to particular examples, the back panel 18 may be white, may be partially or fully reflective, may be adapted to only reflect light of particular colors, or may have any other surface properties. The back panel may, by way of non-limiting example only, comprise or consist of a printed circuit board (PCB), metal core printed circuit board (MCPCB) or metal plate for instance.
[0115]As discussed, the consequence of the described arrangement for an observer is that the observer, looking at the front (outward-facing) surface of the translucent front panel 20, sees a diffuse (functional) background light emanating from across the entirety of the front of the panel, and relatively brighter, narrower spots of light appearing superposed on top emanating from particular light exit areas 32. Each of said bright spots or sparkles appears visible to an observer only when there is complete alignment between the observer's eye, the light exit area in question and one of the primary light sources disposed within the chamber. When this situation does not exist, no direct optical path exists between the given primary light source and the observer's eye, and hence the relatively bright sparkle appears to vanish, and only the background light appears to emanate from the location of the respective light exit area.
[0116]This effect is illustrated more clearly in FIG. 2, which shows a schematic representation of the effect in relation to a particular light exit area 32a for an observer located at a distance d from the translucent front panel 20 of the device. The figure illustrates for each of the primary light sources 28 proximal to the light exit area 32a in question the maximal range of angles over which light emitted by the respective primary light sources is able to propagate through the light exit area and reach a point along the plane at distance d. The two arrows extending from each of the respective primary light sources represent the boundaries of the respective angular range.
[0117]The particular angular constraints of the three primary light sources 28 provide three discrete linear (as represented in this 2D schematic diagram) regions A, B, C along the distance d line within which light emitted by one of the primary light sources is able to directly enter the eye of an observer located at that position through light exit area 32a. Outside of regions A, B and C, no direct light is able to reach distance d through light exit area 32a from any of the three proximal primary light sources. Hence, outside of regions A, B and C, only a lower level of (mixed), background (functional) light is able to reach an observer's eye at distance d via exit area 32a, and so to an observer in those regions, the exit area does not appear as the source of a bright sparkle.
[0118]The same effect illustrated for light exit area 32a in FIG. 2 is replicated for each of the light exit areas across the panel, so that an observer moving relative to the panel along a line or plane at distance d is almost continually moving into and out of respective sparkle-visible zones corresponding to each of the light exit areas across the panel. The optical effect is the observance of different virtual bright spot light sources, emanating from the various light exit areas, constantly appearing and vanishing sharply in response to movement. This effect is referred to in this application, and in the art, as spatially dynamic sparkling or glittering; sparkling which is effected by movement.
[0119]It is noted that it can be seen from FIG. 2 that the intended sparkling effect is in fact only created for observers positioned at a certain minimum distance from the translucent front panel 20. At small distances from the front panel, the three visible zones converge together, such that for each light exit area, the area is visible across a broad, substantially continuous range of angles. In addition, because the areas converge, light from more than one primary light source may enter an observer's eye at a given time, potentially breaking the illusion of a single bright point source appearing to emanate from the light exit areas.
[0120]The sparkling effect created is illustrated schematically inFIG. 3 which depicts an example series of views of the device as seen from different positions along a fixed, or substantially fixed, distance from the panel. As an observer moves from a first position, to a second, certain of the visible bright spots disappear, and others appear in their place. As the observer moves, again, some of the bright spots appear to vanish from view, and different spots come instead into view. As the observer moves further along, spots which previously disappeared may reappear again, as they enter into a different visible zone for the respective light transmissive area.
[0121]The rate of change between the different ‘frames’ illustrated by way of demonstration in FIG. 3, with respect to lateral motion, may be engineered to have one of a range of different values, by configuring the relative positions of the light exit areas and primary light sources appropriately. Changes may for example be desired to be extremely rapid, such that transitions between ‘frames’ appears almost continuous or seamless. Alternately, a more disjointed, discrete twinkling or sparkling may be desired, in which the case, the rate of change might be engineered accordingly. The intended end use of the product may have to be considered, since this may affect the average rate at which a typical observer of the device may in practice be expected to move past it.
[0122]In examples, one or more of the internal surfaces of the chamber—formed, for the example of FIG. 1 by interior surfaces of the side panels 22, 24 and back panel 18—may be partially or fully reflective. Such partial or full reflectivity may assist in emitting from the chamber 14 a maximal level of functional light for illuminating the space within which the lighting device is placed. Reflective internal surfaces may provide a light mixing functionality—so that the chamber functions as a light mixing chamber—thereby improving the uniformity of the background, functional light emitted from the chamber.
[0123]According to particular examples, one or more of the internal surfaces of the chamber may be white, so as to thereby reflect light of spectral compositions corresponding to all color components of light. In further examples, one or more of the internal surfaces may be specularly reflective, or mirrored, surfaces.
[0124]As discussed above, in order to provide suitably bright functional light, it may be necessary to configure or adjust the primary light sources 28 to emit light at an intensity or brightness which, were it permitted to pass unimpeded through the light exit areas 32, would be of a dangerous or at least uncomfortable brightness for an observer looking at the lighting device.
[0125]Accordingly, in accordance with one or more embodiments, the lighting device may further comprise one or more optical elements each arranged in optical communication with one or more of the plurality of light exit areas, wherein each optical element is adapted to absorb or deflect a portion of the light incident at them.
[0126]An example of such an embodiment is illustrated in FIG. 4. The example comprises the same lighting device arrangement as described in relation to FIG. 1, but wherein each of the light exit areas 32 is fully covered by a respective filter element 36, adapted to absorb a portion of the light incident at it, and transmit only the remaining portion. This has the effect of dimming the light which is emitted via each of the light exit areas 32, in comparison with the light being directly emitted from the primary light sources 28, meaning that the intensity of the primary light sources 28 may be increased to provide sufficiently bright functional illumination, while not at the same time risking exposure of observers to dangerous or uncomfortable levels of light through the light exit areas 32.
[0127]Although each of the filter elements 36 is configured to dim or attenuate the light passing through it, it is emphasized that in all examples, the transmittance of each of the light exit areas 32 (including the filter element 36) remains higher than that of the translucent front panel 20. This ensures that light emitted directly from a primary light source 28, through a given light exit area 32, remains relatively brighter than the background illumination and hence remains visible as a bright sparkle superposed on top of this background.
[0128]The filter elements may in examples comprise polarizing elements or other varieties of filter configured to reduce the intensity of light passing through them.
[0129]It is noted that, although in the particular example of FIG. 4, the light exit areas 32 are each covered by respective filter elements 36, in other examples different varieties of optical element might equivalently be used to achieve the same effect. For instance, light deflecting elements might be utilized to deflect, e.g. refract, a portion of the light that might otherwise be emitted through each of the light exit areas.
[0130]Alternatively, light reflecting elements might be used, configured to reflect a portion of the light that would otherwise be emitted through each light exit area. This light is then re-directed back into the chamber 14, where it may be reflected by internal surfaces of the chamber before being propagated once again toward the translucent front panel and/or one or more of the light exit areas 32. In examples, the light reflecting elements may comprise or constitute mirror layers or elements, applied to light exit areas by foil or vapor deposition for example. In some examples, reflective elements may comprise reflective ‘screen’ print arrangements, wherein an otherwise clear window element is covered by a patterned screen or film applied to its surface. An example of such an arrangement is schematically depicted in FIG. 5 which shows a light exit area 32 comprising a white reflective ‘screen’ print (shown in black).
[0131]Although in the example of FIG. 4, each of the filter elements 36 is shown disposed directly beneath each of the light exit areas 32, fully covering the light exit areas 32, it is noted that in alternative examples, the filter element (or other optical element) might be alternatively arranged while still providing the same technical effect. In particular, the optical elements may be arranged in any of a variety of positions that falls along one or more optical axes extending between one or more of the primary light sources and one or more of the light exit areas. In this way, light from the primary light sources still falls incident at said optical elements on its path toward the light exit areas, but without the optical elements being positioned directly beneath the light exit area.
[0132]Additionally, in accordance with one or more examples the optical elements may be comprised by or partly constitute one or more of the light exit areas themselves. In particular examples, each of the light exit areas may be fully comprised by a respective filter element 36 for instance. In other examples, a light exit area may be formed by a window element partially comprised by a filter element, and partially comprised by an otherwise fully light transmissive portion.
[0133]The above described example embodiments incorporating additional optical elements constitute one set of example solutions to the problem of enabling high functional light output while preventing undesirably high sparkling light output. However, alternative solutions also exist. In accordance with one set of example embodiments, there are provided two distinct sets of primary light sources, each configured, or configurable, to emit light at a different intensity or luminance. The first set of primary light sources may be configured to emit light at a relatively high intensity, and arranged within the chamber so that said light is only directly incident at one or more portions of the translucent surface portion and not at any of the light exit areas. The second set of primary light sources may be configured to emit light of a relatively lower intensity, and arranged within the chamber so that said light does fall directly incident at one or more of the light exit areas. Only this lower level of light is able to directly exit the chamber via one of the light exit areas, and hence only this lower level of light will be able to fall directly incident at an observer's eye. This directly incident light generates the sparkle light effect.
[0134]Note that although only the lower intensity of light is utilized in forming the sparkle effect, this may still appear as a brighter spot compared to the functional background light by virtue of the relatively higher optical transmittance of each exit area compared to surrounding translucent front panel.
[0135]In particular examples, the first and second sets of primary light sources may be adapted to have fixed, pre-set absolute intensity values. In other examples, each of the first and second sets of primary light sources may have individually adjustable output intensities, such that a user may set the respective intensities at an appropriate level. It may be that in practice, the lighting device provides functionality for a user only to adjust the output intensity of the set not directly aimed light exit areas.
[0136]According to yet further examples, the lighting device may further comprise a controller, configured to adjust the output intensity of one set of primary light sources in dependence upon an output intensity of another set of primary light sources. Where the first set of primary light sources is arranged to avoid directing light onto any light exit area, and the second set of primary light sources is configured to emit light which does fall incident at light exit areas, then the controller may be configured to adjust the output intensity of the second set of primary light sources in dependence upon the first set of primary light sources. This may allow the output intensity of the first set of primary light sources to be user defined, while maintaining the relative intensities, or intensity difference, between the two sets of primary light sources at a fixed level or within some fixed range. The fixed relative intensity is important in ensuring that the bright sparkles remain bright enough to still be visible against the background illumination.
[0137]In some examples, the relative intensity or intensity difference itself may be configured to be user-adjustable. This may allow the apparent or relative brightness of the sparkles to be user-defined.
[0138]Although the above examples have been described in relation to two sets of primary light sources, as will be readily appreciated by the skilled person, the same concept may be applied to an arrangement comprising any number of different sets of primary light sources.
[0139]According to further examples, the balancing of relative intensities may be achieved simply through dimensional considerations. For example, the light exit areas may be pre-fabricated to have smaller or larger diameters in order to permit a greater or lesser total radiant flux through each area. Where a relatively brighter functional illumination is desired to be provided by the device, the light exit areas may be fabricated relatively smaller, while where a relatively dimmer level of functional light is acceptable or desirable, the light exit areas may be fabricated to be relatively larger.
[0140]In FIG. 6 is illustrated a further example embodiment of the invention, comprising an additional panel element 37 arranged in front of the translucent front panel 20 of the lighting device chamber 14. The surface of this additional panel element 37 facing away from the translucent front panel 20 is the exposed outer surface of the lighting device 12. Light emitted from the chamber falls incident on the second panel 37, through which is it transmitted to illuminate the space, and to provide the sparkle effect. The additional panel provides opportunities for creating an alternative or additional aesthetic effect. In this example, the plurality of virtual secondary light sources is located on the surface of the additional panel element 37 that faces away from the translucent front panel 20, and no longer coincide with the light exit areas 32.
[0141]According to one set of examples for instance, the additional panel element 37 is a solid, continuous translucent panel, and light incident at the panel from the chamber is (partially) transmitted through its surface (and partially reflected). This may create a slight blurring or diffusing or clouding of the sparkle effect, which may be desirable for certain applications.
[0142]According to an alternative set of examples, the panel comprises a translucent panel having light transmissive holes formed through its surface. These holes allow for a further shaping or manipulating of the light exiting the lighting device. FIG. 7 schematically depicts one example ‘view’ from the front of the panel, where such an arrangement is used. Here the white dots no longer represent sparkles, but rather Lambertian light dots emitted through the provided light transmissive holes. In examples, the additional translucent panel may have smaller and/or (much) larger holes, providing a novel mixed effect of Lambertian output and superposed sparkling.
[0143]In examples, the additional translucent panel 37 may have a transmittance as low as 1%. However, any other level of transmittance, e.g. higher levels of transmittance, may also be used.
[0144]According to a further related example, the lighting device may be arranged or configured to project its light output (both Lambertian functional output and sparkle effect output) onto a further opaque surface, arranged opposing the exterior side of the translucent front panel, i.e. exterior to the chamber 14, either directly, or at an oblique angle. This surface may be provided as part of the lighting device of the invention, or may be provided separately, for example a surface forming part of the space or area within which the lighting device is installed such as a wall, ceiling or floor.
[0145]Further interesting aesthetic effects may advantageously be achieved by inventive use of further optical layers and elements. According to one example aspect of the invention for instance, there may be provided a lighting device assembly formed of a lighting device in accordance with any embodiment of the invention and a fluid delivery means for continuously providing a light transmissive fluid across the front of the panel. The light transmissive fluid might for instance comprise smoke or another partially light transmissive gas or vapor, such as dry-ice vapor. In further examples, the fluid may comprise a gas mixture, or may alternatively comprise a liquid for instance. This may create a relatively thic