A lighting device

Abstract

A lighting device (1) comprising a first electrode (3), a second electrode (4), and at least one dielectric element (5), each of which having a first major surface (3a, 4a, 5a) and a second major surface (3b, 4b, 5b) opposite to the first major surface(3a, 4a, 5a), the dielectric element(s) (5) being arranged between and coupled to the first major surface (3a) of the first electrode (3) and the second major surface (4b) of the second electrode (4) at the second major surface (5b) and the first major surface (5a), respectively, of the dielectric element(s) (5). At least part of light emitted by at least one light source (6) is reflected by the first major surface (3a) of the first electrode (3) and / or the first major surface (4a) of the second electrode (4). At least one of the first major surface (3a) of the first electrode (3), the second major surface (4b) of the second electrode (4) and one or more of the first and second major surfaces (5a, 5b) of the dielectric element(s) (5) has a structure such that, when there is an electrical field across at least a portion of the dielectric element(s) (5), at least one portion of the dielectric element(s) (5) is deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature.

Description

[0001] A LIGHTING DEVICE

[0002] TECHNICAL FIELD

[0003] The present invention relates to a lighting device.

[0004] BACKGROUND

[0005] Caustics is a light phenomenon which occurs naturally where parallel light rays from the sun have been continuously reflected or refracted by a curved surface, or where the parallel light rays are projected onto another surface after having been continuously reflected or refracted by a reflective and / or refractive material such as water, creating intriguing patterns of varying light intensity on the projection surface. Compared to the unpredictable dynamics of a natural caustic surface such as a water surface, the caustic projections of static artificial surfaces are at best impressive. Also, it may require relatively expensive, high resolution imaging devices, which generally involve an array of devices forming a ‘pixelated’ surface, to artificially reproduce the smooth and stepless caustic dynamics which occur naturally in nature.

[0006] W02009 / 104122A1) discloses a device for generation and projection of dynamic caustics, comprising a light source and a device for dynamic refraction of the incident light. The installation comprises an effects surface made of a deformable material, and is provided with means to make a determined deformation.

[0007] SUMMARY

[0008] In view of the above, a concern of the present invention is to provide a lighting device capable of providing variable caustic dynamics at a relatively high resolution (i.e., with a sufficient smoothness) and which is relatively inexpensive.

[0009] According to a first aspect of the present invention, a lighting device is provided. The lighting device is configured to, in operation, emit device light. The lighting device comprises a first electrode, a second electrode, and at least one dielectric element. Each of the first electrode, the second electrode and the dielectric element(s) has a first major surface and a second major surface opposite to the first major surface. The dielectric element(s) is arranged between and coupled to the first major surface of the first electrode and the second major surface of the second electrode at the second major surface and the first major surface, respectively, of the dielectric element(s). At least one of the first electrode and the second electrode is flexible. At least one of the first major surface of the first electrode and the first major surface of the second electrode is at least in part light-reflective. The lighting device comprises at least one light source. The at least one light source is configured to, in operation, emit light source light towards the first major surface of the second electrode, wherein the device light comprises at least part of the light source light reflected by the first major surface of the first electrode and / or the first major surface of the second electrode. The lighting device comprises at least one voltage generator. The at least one voltage generator is connected to the first electrode and to the second electrode and configured to selectively and controllably generate a voltage so as to generate an electrical field across at least a portion of the dielectric element(s). The dielectric element(s) is configured to elastically deform when there is an electrical field across at least a portion of the dielectric element(s). At least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) has a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), at least one portion of the dielectric element(s) is deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature.

[0010] In alternative, or in addition, at least one of the first major surface of the first electrode and the second major surface of the second electrode may be arranged in relation to the second major surface and the first major surface, respectively, of the dielectric element(s) such that, when there is an electrical field across at least a portion of the dielectric element(s), at least one portion of the dielectric element(s) is deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature.

[0011] There are different configurations of the first electrode, the second electrode and / or the dielectric element(s) which are possible in order to achieve that at least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) has a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), at least one portion of the dielectric element(s) is deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature. Such different configurations will be described in the following. A configuration of the first electrode, the second electrode and / or the dielectric element(s) to achieve that at least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) has a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), at least one portion of the dielectric element(s) is deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature, may be referred to as “sub-patterning” of the first electrode, the second electrode and / or the dielectric element(s) in the following without any loss of generality.

[0012] It is to be understood that at least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) may have a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), each of a plurality of different portions of the dielectric element(s) is deformed such that one or more of its first and second major surfaces in the portion has a varying surface curvature. At least some of the said plurality of different portions may be contiguous. At least some of the said plurality of different portions may be non-contiguous. Some of the said plurality of different portions may be contiguous while other ones of the said plurality of different portions may be noncontiguous.

[0013] Further, it is to be understood that least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) may have a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), for at least one other portion of the dielectric element(s) (e.g., one or more portions of the dielectric element(s) different from the one or more portions of the dielectric element(s) that is or are deformed when there is an electrical field across at least a portion of the dielectric element(s) such that one or more of its first and second major surfaces in the portion(s) has a varying surface curvature), one or more of its first and second major surfaces in the at least one portion has a non-varying surface curvature.

[0014] Portions of the dielectric element(s) which have a varying surface curvature when the electrical field is applied may be contiguous with portions of the dielectric element(s) which have a non-varying surface curvature when the electrical field is applied.

[0015] By (z) at least one portion of the dielectric element(s) being deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature when the electrical field is applied, by (zz) the dielectric element(s) being arranged between and coupled to the first major surface of the first electrode and the second major surface of the second electrode at the second major surface and the first major surface, respectively, of the dielectric element(s), and by (zzz) at least one of the first electrode and the second electrode being flexible, at least one of the first electrode and the second electrode may as a result be locally deformed in accordance with the deformation of the said at least one portion of the dielectric element(s) when the electrical field is applied. Thereby, the optical path of the light source light having reflected by the first major surface of the first electrode and / or the first major surface of the second electrode can be locally altered at one or more positions across the first major surface of the first electrode and / or the first major surface of the second electrode corresponding to the respective ones of the one or more portions of the dielectric element(s) which have a varying surface curvature when the electrical field is applied, as compared to if the dielectric element(s) would have a nonvarying surface curvature (when the electrical field is applied) throughout the dielectric element(s). The inventors have realized that by such configurations, the light emitted by the lighting device (e.g., the device light) can provide variable caustic dynamics at a relatively high resolution (i.e., with a sufficient smoothness). As mentioned, the device light comprises at least part of the light source light reflected by the first major surface of the first electrode and / or the first major surface of the second electrode. Further, provisioning of such variable caustic dynamics may be achieved without or at least with less need for any relatively expensive, high resolution imaging devices to artificially reproduce the smooth and stepless caustic dynamics which occur naturally in nature.

[0016] By at least one portion of the dielectric element(s) being deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature when there is an electrical field across at least a portion of the dielectric element(s), there may be entailed that the said at least one portion of the dielectric element(s) is deformed in a non-uniform manner, such that the one or more of its first and second major surfaces in the at least one portion is or are non-flat. As mentioned, portions of the dielectric element(s) which have a varying surface curvature when the electrical field is applied may be contiguous with portions of the dielectric element(s) which have a non-varying surface curvature when the electrical field is applied. By configurations such as described above and elsewhere herein, localized and possibly stepless non-uniformities in deformation of a surface of one or more portions of the dielectric element(s) can be introduced when the electrical field is applied, as compared to other portions of the dielectric element(s) which may deform in a uniform manner when the electrical field is applied. Each of such portion(s) of the dielectric element(s) deforming in a non-uniform manner when the electrical field is applied may readily give rise to caustic dynamics visible to a viewer on a surface onto which the device light is incident. Portions of the dielectric element(s) which have a varying surface curvature when the electrical field is applied may be distributed in or on the dielectric element(s), e.g., evenly distributed, for example among portions of the dielectric element(s) which may deform in a uniform manner when the electrical field is applied.

[0017] The caustic dynamics provided by the device light may be tailored or customized, such as with respect to the particular way in which light source light reflected by the first major surface of the first electrode and / or the first major surface of the second electrode is focused or diverted, by the particular way of realizing the “sub-patterning” of the first electrode, the second electrode and / or the dielectric element(s). There are different ways of realizing the “sub-patterning”, examples of which will be described in the following.

[0018] Compared to imaging devices involving an array of devices forming a ‘pixelated’ surface for achieving caustic effects, the “sub-patterning” as described herein can achieve more random caustic effects, which may facilitate or enable reproducing the smooth and stepless caustic dynamics which occur naturally in nature. In particular, the need for a visible repetition of the same image forming elements of an array of devices forming a ‘pixelated’ surface for achieving caustic effects can be reduced or even eliminated by means of the “sub-patterning” as described herein.

[0019] One or more of the first and second major surfaces of the dielectric element(s) may be one or more holes (e.g., through-holes) and / or one or more cavities, recesses or indentations. Thus, the “sub-patterning” may be achieved by having a certain (e.g., surface) topography of the dielectric element(s).

[0020] In alternative or in addition, at least one of the first major surface of the first electrode and the second major surface of the second electrode may have one or more protrusions (e.g., one or more ‘bumps’), and the second major surface and the first major surface, respectively, of the dielectric element(s) may have one or more cavities, recesses or indentations, which may correspond to and (e.g., be configured to) mate with respective ones of the one or more protrusions. Thus, the “sub-patterning” may be achieved by having a certain topography of the first electrode and / or the second electrode.

[0021] Recesses, indentations, etc., in or on the first electrode, the second electrode and / or the dielectric element(s) may for example be realized by scratching at or making one or more dents in the first or second major surface thereof. According to another example of how the “sub-patterning” may be achieved, which may be used in alternative or in addition to any other example described herein, the at least one dielectric element may comprise a dielectric layer made of a first dielectric material. The first major surface and the second major surface of the at least one dielectric element may be constituted by a first major surface and a second major surface of the dielectric layer. The at least one dielectric element may comprise one or more dielectric particles which may be arranged at one or more of the first major surface and the second major surface of the dielectric layer. The one or more dielectric particles may be made of a dielectric material different from the first dielectric material. By the arrangement of the one or more dielectric particles, made of a dielectric material different from the first dielectric material, at one or more of the first major surface and the second major surface of the dielectric layer, the local electric field strength can be modified.

[0022] According to another example of how the “sub-patterning” may be achieved, which may be used in alternative or in addition to any other example described herein, the at least one dielectric element may comprise a first dielectric element and one or more second dielectric elements. The first dielectric element may comprise a dielectric layer made of a first dielectric material. One or more of a first major surface and a second major surface of the dielectric layer may comprise one or more cavities, recesses or indentations corresponding to and in which a respective one(s) of the one or more second dielectric elements are arranged. Each of the one or more second dielectric elements may be made of a dielectric material different from the first dielectric material.

[0023] At least one of the first major surface of the first electrode and the second major surface of the second electrode may be arranged in relation to the second major surface and the first major surface, respectively, of the dielectric element(s), or vice versa, such that one or more at least in part enclosed pockets are formed between the at least one dielectric element and the first major surface of the first electrode and the second major surface of the second electrode, respectively.

[0024] The at least one light source may comprise a plurality of light sources. The plurality of light sources may be configured to, in operation, emit light towards different portions of the first major surface of the second electrode, or towards the same portion of the first major surface of the second electrode.

[0025] For example, with respect to the possibility of emitting light towards different portions of the first major surface of the second electrode, light may be emitted towards a certain portion of the first major surface of the second electrode, e.g., using a free-shape shadow masking portion, a narrow beam collimated light source, or a plurality of line sources, for example, which portion may correspond to a portion of the dielectric element(s) which has a varying surface curvature when the electrical field is applied. Thereby, for one of the light sources, light may be deflected when the electrical field is applied but not in the same way as for other light sources which may emit light towards portions of the first major surface of the second electrode corresponding to portions of the dielectric element(s) which have a non-varying surface curvature when the electrical field is applied. Such a configuration may reduce the perception of synchronous motion of the entire light field of the device light when the electrical field is applied.

[0026] The plurality of light sources may be positioned so as to be distributed over at least a portion of an imaginary hemispherical surface. For example, the plurality of light sources may be positioned along a semi-circle or a portion of a semi-circle. Positioning the plurality of light sources so as to be distributed over at least a portion of an imaginary hemispherical surface or along a semi-circle or a portion of a semi-circle may for example facilitate providing a relatively large illuminated area on, e.g., a wall, for example an area of several square meters, with the lighting device. The plurality of light sources may be configured to emit light having the same or different spectral wavelength, color and / or tonality, etc.

[0027] The at least one light source may comprise at least a first light source and a second light source. The first light source may be configured to, in operation, emit collimated light. The second light source may be configured to, in operation, emit diffuse light. The first light source may for example comprise a laser light source.

[0028] Each or any light source of the at least one light source may be controllable with respect to operation thereof.

[0029] The lighting device may comprise a controller. The controller may be configured to control operation of each light source of the at least one light source. Each or any light source of the at least one light source may be controllable for example with respect to dimming and / or fading of the light emitted by the light source. The controller may be configured to control operation of each or any light source of the at least one light source, e.g., at least with respect to dimming and / or fading of the light emitted by each or any light source of the at least one light source. The dimming and / or fading of the light emitted by different light sources may be different. For example, the dimming and / or fading of the light emitted by different light sources in a certain wavelength range may be different. The controller may be configured to control a ratio between dimming and / or fading of the light emitted by the first light source and dimming and / or fading of the light emitted by the second light source. The controller may be configured to control operation of each or any light source of the at least one light source with respect to intensity or brightness and / or another characteristic of the emitted light.

[0030] The first major surface of the second electrode may be at least in part light- reflective. In another configuration, the second electrode may be light-transmissive, and the first major surface of the first electrode may be at least in part light-reflective.

[0031] Each or any light source of the at least one light source may for example comprise a solid state emitter, such as one or more light-emitting diodes (LEDs) and / or one or more lasers. Each or any LED may for example include or be constituted by an inorganic LED and / or an organic LED (OLED). Solid state light emitters are relatively cost-efficient light sources since they in general are relatively inexpensive and have a relatively high optical efficiency and a relatively long lifetime. Examples of LEDs include semiconductor, organic, or polymer / polymeric LEDs, optically pumped phosphor coated LEDs, optically pumped nano-crystal LEDs or any other similar devices as would be readily understood by a person skilled in the art. For example, the term LED can encompass a bare LED die arranged in a housing, which may be referred to as a LED package. According to another example, the term LED can encompass a Chip Scale Package (CSP) LED, which may comprise a LED die directly attached to a substrate such as a printed circuit board (PCB), and not via a submount. The term LED can for example encompass a laser diode, because a laser diode is a diode which emits light.

[0032] The controller may for example comprise one or more processors, control units, control devices, etc., each or any of which for example may include or be constituted by any suitable central processing unit (CPU), microcontroller, digital signal processor (DSP), Application Specific Integrated Circuit (ASIC), Field Programmable Gate Array (FPGA), etc., or any combination thereof. The controller or one or more control units, control devices, etc., may optionally be capable of executing software instructions stored in a computer program product, e.g., in the form of a memory. The memory may for example be any combination of read and write memory (RAM) and read only memory (ROM). The memory may comprise persistent storage, which for example can be a magnetic memory, an optical memory, a solid state memory or a remotely mounted memory, or any combination thereof.

[0033] The controller or one or more control units, control devices, etc., may for example comprise driver circuitry (e.g., LED driving circuitry) for controlling supply of power to the respective ones of the light source(s) and / or for controlling operation of the respective ones of the light source(s). The driver circuitry may for example comprise driver circuitry configured to drive (or control operation of) the respective ones of the light source(s). The controller or one or more controllers, control units, control devices, etc., may be configured to control operation of the respective ones of the light source(s) for example by way of transmitting at least one control signal or control message or the like to the respective ones of the light source(s).

[0034] Each of the first electrode, the second electrode and the dielectric element(s) may be flexible, whereby the lighting device may be flexible so as to be, for example, foldable.

[0035] Several lighting devices in accordance with the first aspect of the present invention may be connected in series or in parallel, and / or may be stacked. The lighting devices may be associated with different dielectric constants of the respective dielectric element(s), different size of the dielectric element(s), the first electrode and / or the second electrode, etc. Thereby, different ones of the lighting devices may provide different caustic dynamics.

[0036] According to a second aspect of the present invention, a lighting system is provided. The lighting system may be selected from a group consisting of a lamp, a luminaire or a projector device comprising a lighting device according to the first aspect of the present invention.

[0037] Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments. It is noted that the present invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the description herein. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described herein.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Exemplifying embodiments of the invention will be described below with reference to the accompanying drawings.

[0040] Each of Figs. 1 to 11 is a schematic cross-sectional view of a lighting device according to an embodiment of the present invention.

[0041] Fig. 12 is a schematic view of lighting systems according to embodiments of the present invention. All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate embodiments of the present invention, wherein other parts may be omitted or merely suggested.

[0042] DESCRIPTION WITH REFERENCE TO THE DRAWINGS

[0043] The present invention will now be described hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments of the present invention set forth herein; rather, these embodiments of the present invention are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art. In the drawings, identical reference numerals denote the same or similar components having a same or similar function, unless specifically stated otherwise.

[0044] Figure 1 is a schematic cross-sectional view of a lighting device 1 according to an embodiment of the present invention. The lighting device 1 is configured to, in operation, emit device light, schematically indicated by the arrow at 2.

[0045] The lighting device 1 comprises a first electrode 3, a second electrode 4, and a dielectric element 5. While Figure 1 illustrates one dielectric element 5, the lighting device 1 could comprise several dielectric elements, such as described elsewhere herein. Each of the first electrode 3, the second electrode 4 and the dielectric element 5 has a first major surface 3a, 4a, and 5a, respectively, and a second major surface 3b, 4b, and 5b, respectively, which is opposite to the first major surface 3a, 4a, and 5a, respectively. The dielectric element 5 is arranged between and coupled to the first major surface 3 a of the first electrode 3 and the second major surface 4b of the second electrode 4 at the second major surface 5b and the first major surface 5a, respectively, of the dielectric element 5.

[0046] While not illustrated in Figure 1 or in any of the other figures, the first electrode 3 may be arranged on a carrier substrate. The second major surface 3b of the first electrode 3 may be facing (e.g., a major surface of) the carrier substrate. The carrier substrate may be light-transmissive, and may for example be made of glass, polyethylene terephthalate, polyethylene naphthalate, and / or a similar material.

[0047] It is to be noted that even though according to Figure 1 (as well as Figures 2 to 11) the first electrode 3 and the second electrode 4 are indicated to have a planar shape or a layered configuration, this is not required and each of the first electrode and the second electrode may in principle have any shape, such as, for example, a rod shape, a curved and / or waved shape, a three-dimensional curved shape, a shape as a bowl, a shape as a convex or concave disc. Likewise, the dielectric element 5 must not necessarily have a planar shape or a layered configuration, but could, in principle, have any shape. Per the illustrated embodiments of the present invention, the first electrode 3 and the second electrode 4 may be of different size (and / or shape). For example, as per the illustrated embodiments of the present invention, the first electrode 3 may be larger than the second electrode 4.

[0048] At least one of the first electrode 3 and the second electrode 4 is flexible.

[0049] The first electrode 3 and / or the second electrode 4 may for example comprise or be constituted by a relatively thin, and possibly flexible, film or foil. The first electrode 3 and / or the second electrode 4 may for example be made of gold, silver, aluminium, chromium, copper, platinum, titanium, carbon, composites thereof, and / or (e.g., semiconducting) oxides thereof (e.g., TiCh). The first electrode 3 and the second electrode 4 may be made of the same material or may be made of different materials.

[0050] The dielectric element 5 may for example comprise an elastic polymer film or foil, which may have a relatively small thickness. The elastic polymer film or foil may for example be cladded between the first electrode 3 and the second electrode 4, whereby, essentially, a soft capacitor stack may be formed.

[0051] At least one of the first major surface 3 a of the first electrode 3 and the first major surface 4a of the second electrode 4 is at least in part light-reflective. At least one of the first major surface 3 a of the first electrode 3 and the first major surface 4a of the second electrode 4 may be at least in part specularly reflective for light, or substantially specularly reflective for light. For example, the first major surface 3a of the first electrode 3 and / or the first major surface 4a of the second electrode 4 may be formed by a relatively thin film of aluminum which has been evaporated on a flexible (and optionally transparent, e.g., made of plastic) carrier.

[0052] The lighting device 1 comprises at least one light source 6. While Figure 1 illustrates one light source 6, the lighting device 1 could comprise several light sources, such as described elsewhere herein. The light source 6 is configured to, in operation, emit light source light, which is schematically indicated by the arrow at 7, towards the first major surface 4a of the second electrode 4. The device light 2 comprises at least part of the light source light 7 reflected by the first major surface 3a of the first electrode 3 and / or the first major surface 4a of the second electrode 4. To that end, the first major surface 4a of the second electrode 4 may be at least in part light-reflective, or the second electrode 4 may be light-transmissive and the first major surface 3a of the first electrode 3 may be at least in part light-reflective. The dielectric element 3 may be light-transmissive.

[0053] Each or any light source of the lighting device 1, e.g., the light source 6 illustrated in Figure 1, may be controllable with respect to operation thereof.

[0054] In accordance with the embodiment of the present invention illustrated in Figure 1, the lighting device 1 comprises a controller 18. Generally, the controller 18 may be configured to control operation of each or any light source of the lighting device 1. In accordance with the embodiment of the present invention illustrated in Figure 1, the controller 18 may be configured to control operation of the light source 6. Although Figure 1 indicates a wireless connection between the controller 18 and the light source 6, it is to be understood that the controller 18 and the light source 6 (and any other light source which may be included in the lighting device 1) may be connected via one or more wired connections and / or one or more wireless connections, e.g., by way of any appropriate wired and / or wireless connections as known in the art. The controller 18 may be configured to control operation of the light source 6 (and / or any other light source which may be included in the lighting device 1) for example by way of transmitting at least one control signal or control message or the like to the light source 6.

[0055] The lighting device 1 comprises a voltage generator, which is schematically indicated at 8 and which is connected to the first electrode 3 and to the second electrode 4. The voltage generator 8 is configured to selectively and controllably generate a voltage so as to generate an electrical field across at least a portion of the dielectric element 5. The dielectric element 5 is configured to elastically deform when there is an electrical field across at least a portion of the dielectric element 5. The voltage generator 8 may for example be realized or implemented for example in accordance with any voltage generator as known in the art appropriate for generating voltages which can be used to generate an electrical field (e.g., a variable electrical field) across at least a portion of the dielectric element(s) 5. For example, the voltage generator 8 may be arranged and / or configured to selectively and controllably generate a voltage so as to generate an electrical field across one or more selected portions of the dielectric element 5, which portion(s) could be referred to as “pixel(s)”, while there may be no electrical field generated across one or more other portions of the dielectric element 5.

[0056] Generally, at least one of the first major surface 3 a of the first electrode 3, the second major surface 4b of the second electrode 4 and one or more of the first and second major surfaces 5a, 5b of the dielectric element 5 has a structure such that, when there is an electrical field across at least a portion of the dielectric element 5, at least one portion of the dielectric element 5 is deformed such that one or more of its first and second major surfaces 5a, 5b in the at least one portion has a varying surface curvature.

[0057] To that end, and in accordance with the embodiment of the present invention illustrated in Figure 1, the dielectric 5 comprises a through-hole, such that both of the first and second major surfaces 5a, 5b of the dielectric element 5 have a hole 9. Further, in accordance with the embodiment of the present invention illustrated in Figure 1, the first major surface 5a of the dielectric element 5 has a recess or indentation 10. Holes in dielectric element 5 will generally modify the local effective dielectric constant of the material of the dielectric element 5. When the dielectric element 5 deforms as a result of the electrical field being applied, the dielectric element when deformed may expand into any holes in dielectric element 5. Any holes in dielectric element 5 may be filled with, e.g., air.

[0058] However, there are other, different configurations which are possible in order to achieve that at least one of the first major surface 3 a of the first electrode 3, the second major surface 4b of the second electrode 4 and one or more of the first and second major surfaces 5a, 5b of the dielectric element 5 has a structure such that, when there is an electrical field across at least a portion of the dielectric element 5, at least one portion of the dielectric element 5 is deformed such that one or more of its first and second major surfaces 5a, 5b in the at least one portion has a varying surface curvature. Such different configurations will be illustrated and described in the following with reference to Figures 2 to 11.

[0059] Each of Figures 2 to 11 is a schematic cross-sectional view of a lighting device 1 according to an embodiment of the present invention. The same reference numerals in Figures 2 to 11 and Figure 1 denote the same or similar components or elements, having the same or similar function. In comparison to Figure 1, some reference numerals have been omitted in Figures 2 to 11, such as for the first and major surfaces of the first electrode 3, the second electrode 4 and the dielectric element 5.

[0060] It is to be noted that the voltage generator 8, the light source 6 and the controller 18 are not illustrated in any of Figures 2 to 11. However, it is to be understood that the lighting device 1 illustrated in each Figures 2 to 11 comprises at least one light source, such as the light source 6 as illustrated in Figure 1, and at least one voltage generator, such as the voltage generator 8 as illustrated in Figure 1, and may comprise a controller such as the controller 18 as illustrated in Figure 1.

[0061] In accordance with the embodiment of the present invention illustrated in Figure 2 and similarly to the embodiment the present invention illustrated in Figure 1, the dielectric element 5 comprises a through-hole, such that both of the first and second major surfaces of the dielectric element 5 have a hole 9. As noted in the foregoing, any holes in dielectric element 5 may be filled with, e.g., air. The dielectric constant of air is smaller than the dielectric constant of the material of the dielectric element 5, which for example may be a polymer. Thereby, the material of the dielectric element 5 may deform around the areas of enclosed air formed by the holes in dielectric element 5. The (e.g., compressed) air within holes in dielectric element 5 may in part cause shaping of the curvature of the first and / or second major surface of, e.g., the second electrode 4, as illustrated in Figure 2, for example creating a wave-like topography.

[0062] In accordance with the embodiment of the present invention illustrated in Figure 3, the dielectric element 5 may comprises several through-holes, such that both of the first and second major surfaces of the dielectric element 5 have several holes 9.

[0063] In accordance with the embodiment of the present invention illustrated in Figure 4, there are interfacial pockets 11 between the second electrode 4 and the dielectric element 5. Generally however, at least one of the first major surface of the first electrode 3 and the second major surface of the second electrode 4 may be arranged in relation to the second major surface and the first major surface, respectively, of the dielectric element 5, or vice versa, such that one or more at least in part enclosed pockets 11 are formed between the dielectric element 5 and the first major surface of the first electrode 3 and the second major surface of the second electrode 4, respectively.

[0064] In accordance with the embodiment of the present invention illustrated in Figure 5, there are several dielectric elements 5, comprising a dielectric layer 13 made of a first dielectric material. The first dielectric material may for example be a polymer. The first major surface and the second major surface of the dielectric element 5 are, according to the illustrated embodiment of the present invention, constituted by a first major surface 13a and a second major surface 13b of the dielectric layer 13. The dielectric elements 5 further comprise dielectric particles 12 arranged at the second major surface 13b of the dielectric layer 13. The dielectric particles 12 may for example be shaped as spheres. The dielectric particles 12 are made of a dielectric material different from the first dielectric material. The dielectric material that is different from the first dielectric material may for example be aluminum oxide. Adding such dielectric particles 12 may effectively increase the local distance between the first electrode 3 and the second electrode 4 and may modify the local dielectric constant. It is to be understood that the number of dielectric particles 12 illustrated in Figure 5 is exemplifying and that there may be more or fewer dielectric particles 12 than what is illustrated in Figure 5. Further, the positioning of the dielectric particles 12 at the second major surface 13b as illustrated in Figure 5 is not limited to only what is illustrated in Figure 5, but variations are possible. Generally, the dielectric elements 5 may comprise one or more dielectric particles 12 arranged at one or more of the first major surface and the second major surface of the dielectric layer 5, wherein the one or more dielectric particles are made of a second dielectric material different from the first dielectric material. The dielectric particles 12 may have different shapes and / or sizes, which may facilitate achieving different modifications of the local dielectric constant. Generally, there could be provided dielectric particles of two or more different dielectric materials, and which may have the same and / or different size(s) distribution(s).

[0065] In accordance with the embodiment of the present invention illustrated in Figure 6, there are several dielectric elements 5, comprising a first dielectric element 13 and several second dielectric elements 14. The first dielectric element 13 comprises a dielectric layer 13 made of a first dielectric material. The first dielectric material may for example be a polymer. According to the illustrated embodiment of the present invention, the second major surface 13b of the dielectric layer 13 comprises recesses or indentations 15, corresponding to and in which a respective one of the one or more second dielectric elements 14 are arranged. Each of the second dielectric elements 14 is made of a dielectric material different from the first dielectric material. The dielectric material that is different from the first dielectric material may for example be aluminum oxide. By a configuration such as with the recesses or indentations 15 in the dielectric layer 13, with the recesses or indentations 15 corresponding to and accommodating a respective one of the second dielectric elements 14, the local dielectric constant may be modified. It is to be understood that the numbers of recesses or indentations 15 and second dielectric elements 14 illustrated in Figure 6 are exemplifying and that there may be more or fewer recesses or indentations 15 and second dielectric elements

[0066] 14 than what is illustrated in Figure 6. Further, the positioning of the recesses or indentations

[0067] 15 at the second major surface 13b as illustrated in Figure 6 is not limited to only what is illustrated in Figure 6, but variations are possible. In general, one or more of a first major surface 13a and a second major surface 13b of the dielectric layer 13 may comprises one or more cavities, recesses or indentations 15 corresponding to and in which a respective one(s) of the one or more second dielectric elements 14 are arranged. At least some of the second dielectric elements 14 may be made of different dielectric materials.

[0068] In accordance with the embodiments of the present invention illustrated in Figures 7 to 9, the first major surface of the first electrode 3 has protrusions 17 and the first major surface of the dielectric element 5 has recesses or indentations 15 corresponding to and mating with respective ones of the protrusions 17. As illustrated in Figures 7 to 9, different shapes of the recesses, indentations and protrusions are possible. It is to be understood that the numbers of recesses or indentations 15 and protrusions 17 illustrated in Figures 7-9 are exemplifying and that there may be more or fewer recesses or indentations 15 and protrusions 17 than what is illustrated in Figures 7-9. Further, the positioning of the recesses or indentations 15 and protrusions 17 as illustrated in Figures 7-9 is not limited to only what is illustrated in Figures 7-9, but variations are possible. In general, at least one of the first major surface of the first electrode 3 and the second major surface of the second electrode 4 may have one or more protrusions 17 and the second major surface and the first major surface, respectively, of the dielectric element 5 may have one or more cavities, recesses or indentations 15 corresponding to and mating with respective ones of the one or more protrusions 17. It is to be noted that while Figures 7 to 9 illustrate the protrusions 17 as monolithically integrated in or on the first electrode 3 (or the second electrode 4), it is to be understood that this is not required, and that the protrusions 17 could be constituted by elements or components coupled to the first electrode 3 (or the second electrode 4), including, for example, conductive particles and / or flakes at the first major surface of the first electrode 3 (or the second major surface of the second electrode 4). Such conductive particles and / or flakes may be similar to the dielectric particles 12 described in the foregoing and illustrated in Figure 5.

[0069] In accordance with the embodiments of the present invention illustrated in Figures 10 and 11, the first major surface of the first electrode 3 has cavities, recesses or indentations 16 forming enclosed pockets (e.g., filled with air) between the dielectric element 5 and the first major surface of the first electrode 3. Such recesses, indentations, etc., in or on an electrode (e.g., the first electrode 3) may for example be realized by scratching at a surface thereof. Such scratches in the first major surface of the first electrode 3 are illustrated in Figure 10. It is to be understood that the number of cavities, recesses or indentations 16 illustrated in Figures 10 and 11 is exemplifying and that there may be more or fewer cavities, recesses or indentations 16 than what is illustrated in Figures 10 and 11. Further, the positioning of the cavities, recesses or indentations 16 as illustrated in Figures 10 and 11 is not limited to only what is illustrated in Figures 10 and 11, but variations are possible. In general, at least one of the first major surface of the first electrode 3 and the second major surface of the second electrode 4 may have one or more cavities, recesses or indentations 16 forming one or more enclosed pockets between the dielectric element 5 and the first major surface of the first electrode 3 and the second major surface of the second electrode 4, respectively. The cavities, recesses or indentations 16 may have different shapes and / or sizes, which may facilitate achieving different modifications of the local dielectric constant.

[0070] Figure 12 is a schematic view of lighting systems 1000 according to embodiments of the present invention. The lighting system 1000 is selected from a group consisting of a lamp 10, a luminaire 20 or a projector device 30, comprising a lighting device according to an embodiment of the present invention, e.g., a lighting device 1 as illustrated in any one of Figures 1 to 11. Figure 12 schematically depicts an embodiment of a luminaire 20 comprising the lighting device. Reference 301 indicates a user interface which may be functionally coupled with a control system 300 comprised by or functionally coupled to the lighting system 1000. Figure 12 also schematically depicts an embodiment of a lamp 10 comprised in the lighting system 1000. Reference 30 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may be comprised in the lighting system 1000. Hence, Figure 12 schematically depicts embodiments of a lighting system 1000 selected from the group of a lamp 10, a luminaire 20, and a projector device 30, comprising a lighting device according to an embodiment of the present invention. In embodiments, such lighting device may be a lamp 10, a luminaire 20, or a projector device 30. Device light emitted by the lighting device is indicated with reference 2. Lighting system light 1001 may essentially consist of device light 2 and may in specific embodiments be device light 2. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor and reference 1310 refers to a ceiling; reference 1307 refers to a wall.

[0071] In conclusion, a lighting device is disclosed. The lighting device comprises a first electrode, a second electrode, and at least one dielectric element, each of which having a first major surface and a second major surface opposite to the first major surface, the dielectric element(s) being arranged between and coupled to the first major surface of the first electrode and the second major surface of the second electrode at the second major surface and the first major surface, respectively, of the dielectric element(s). At least part of light emitted by at least one light source is reflected by the first major surface of the first electrode and / or the first major surface of the second electrode. At least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) has a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), at least one portion of the dielectric element(s) is deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature. While the present invention has been illustrated in the appended drawings and the foregoing description, such illustration is to be considered illustrative or exemplifying and not restrictive; the present invention is not limited to the disclosed embodiments. 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. In the appended claims, the word “comprising” does not exclude other elements or steps, and the indefinite article ”a” or “an” does not exclude a plurality. 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. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A lighting device (1) configured to, in operation, emit device light (2), the lighting device comprising: a first electrode (3), a second electrode (4), and at least one dielectric element (5, 12, 13, 14), wherein each of the first electrode, the second electrode and the dielectric element(s) has a first major surface (3a, 4a, 5a) and a second major surface (3b, 4b, 5b) opposite to the first major surface, and wherein the dielectric element(s) is arranged between and coupled to the first major surface (3 a) of the first electrode and the second major surface (4b) of the second electrode at the second major surface (5b) and the first major surface (5a), respectively, of the dielectric element(s), and wherein at least one of the first electrode and the second electrode is flexible, and wherein at least one of the first major surface of the first electrode and the first major surface of the second electrode is at least in part light-reflective; at least one light source (6) configured to, in operation, emit light source light (7) towards the first major surface of the second electrode, wherein the device light comprises at least part of the light source light reflected by the first major surface of the first electrode and / or the first major surface of the second electrode; and at least one voltage generator (8) connected to the first electrode and to the second electrode and configured to selectively and controllably generate a voltage so as to generate an electrical field across at least a portion of the dielectric element(s), wherein the dielectric element(s) is configured to elastically deform when there is an electrical field across at least a portion of the dielectric element(s); wherein at least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) has a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), at least one portion of the dielectric element(s) is deformed such that one or more of its first and second major surfaces in the at least one portion has a varying surface curvature; and(i) wherein one or more of the first and second major surfaces of the dielectric element(s) has one or more holes (9) and / or one or more cavities, recesses or indentations (10, 15), or (ii) wherein at least one of the first major surface of the first electrode and thesecond major surface of the second electrode has one or more cavities, recesses or indentations (16) forming one or more enclosed pockets between the at least one dielectric element and the first major surface of the first electrode and the second major surface of the second electrode, respectively.

2. A lighting device according to claim 1, wherein at least one of the first major surface of the first electrode, the second major surface of the second electrode and one or more of the first and second major surfaces of the dielectric element(s) has a structure such that, when there is an electrical field across at least a portion of the dielectric element(s), for at least one other portion of the dielectric element(s), one or more of its first and second major surfaces in the at least one portion has a non-varying surface curvature.

3. A lighting device according to any one of claims 1-2, wherein one or more of the first and second major surfaces of the dielectric element(s) has one or more cavities, recesses or indentations (10, 15).

4. A lighting device according to any one of claims 1-3, wherein at least one of the first major surface of the first electrode and the second major surface of the second electrode has one or more protrusions (17) and the second major surface and the first major surface, respectively, of the dielectric element(s) has one or more cavities, recesses or indentations (15) corresponding to and mating with respective ones of the one or more protrusions.

5. A lighting device according to any one of claims 1-4, wherein the at least one dielectric element comprises a dielectric layer (13) made of a first dielectric material, wherein the first major surface and the second major surface of the at least one dielectric element are constituted by a first major surface (13a) and a second major surface (13b) of the dielectric layer, and wherein the at least one dielectric element further comprises one or more dielectric particles (12) arranged at one or more of the first major surface and the second major surface of the dielectric layer, wherein the one or more dielectric particles are made of a dielectric material different from the first dielectric material.

6. A lighting device according to any one of claims 1-5, wherein the at least one dielectric element comprises a first dielectric element (13) and one or more second dielectricelements (14), wherein the first dielectric element comprises a dielectric layer (13) made of a first dielectric material, and wherein one or more of a first major surface (13a) and a second major surface (13b) of the dielectric layer comprises one or more cavities, recesses or indentations (15) corresponding to and in which a respective one(s) of the one or more second dielectric elements are arranged, wherein each of the one or more second dielectric elements is made of a dielectric material different from the first dielectric material.

7. A lighting device according to any one of claims 1-6, wherein the one or more enclosed pockets between the at least one dielectric element and the first major surface of the first electrode and the second major surface of the second electrode, respectively, are filled with air.

8. A lighting device according to any one of claims 1-7, wherein at least one of the first major surface of the first electrode and the second major surface of the second electrode is arranged in relation to the second major surface and the first major surface, respectively, of the dielectric element(s), or vice versa, such that one or more at least in part enclosed pockets (11) are formed between the at least one dielectric element and the first major surface of the first electrode and the second major surface of the second electrode, respectively.

9. A lighting device according to any one of claims 1-8, wherein the at least one light source comprises a plurality of light sources configured to, in operation, emit light towards different portions of the first major surface of the second electrode.

10. A lighting device according to any one of claims 1-8, wherein the at least one light source comprises a plurality of light sources configured to, in operation, emit light towards the same portion of the first major surface of the second electrode.

11. A lighting device according to claim 9 or 10, wherein the plurality of light sources are positioned so as to be distributed over at least a portion of an imaginary hemispherical surface.

12. A lighting device according to any one of claims 1-11, wherein the at least one light source comprises at least a first light source configured to, in operation, emit collimated light, and a second light source configured to, in operation, emit diffuse light.

13. A lighting device according to any one of claims 1-12, where each light source of the at least one light source is controllable with respect to operation thereof, and wherein the lighting device further comprises a controller (18) configured to control operation of each light source of the at least one light source.

14. A lighting device according to any one of claims 1-13, wherein the first major surface of the second electrode is at least in part light-reflective, or wherein the second electrode is light-transmissive and the first major surface of the first electrode is at least in part light-reflective.

15. A lighting system (1000) selected from a group consisting of a lamp (10), a luminaire (20) or a projector device (30), comprising the lighting device (1) according to any one of the preceding claims.

Images