+

WO2014096998A1 - Illumination device and illumination system comprising an illumination device - Google Patents

Illumination device and illumination system comprising an illumination device Download PDF

Info

Publication number
WO2014096998A1
WO2014096998A1 PCT/IB2013/058869 IB2013058869W WO2014096998A1 WO 2014096998 A1 WO2014096998 A1 WO 2014096998A1 IB 2013058869 W IB2013058869 W IB 2013058869W WO 2014096998 A1 WO2014096998 A1 WO 2014096998A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
illumination device
transmitting substrate
illumination
emitting element
Prior art date
Application number
PCT/IB2013/058869
Other languages
French (fr)
Inventor
Rick Gerhardus Nijkamp
Erik Paul Boonekamp
Original Assignee
Koninklijke Philips N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips N.V. filed Critical Koninklijke Philips N.V.
Publication of WO2014096998A1 publication Critical patent/WO2014096998A1/en

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces

Definitions

  • Illumination device and illumination system comprising an illumination device
  • the present invention relates to an illumination device wherein the light generated by at least one light-emitting element arranged at a side or sides of a light- transmitting substrate travels through the light-transmitting substrate.
  • the present invention also relates to an illumination system comprising a first and a second illumination device and a controller for controlling the light output from the first and second illumination devices.
  • Illumination devices emitting light that is comfortable to the eyes, by having e.g. homogeneous output light and a limited peak brightness and glare, are of interest for various lighting purposes, including applications such as office lights, shop lights, shop window lights, and illumination of public places and industry spaces.
  • a backlight device having a transparent substrate wherein light emitting elements are arranged on an upper surface of a transparent substrate. Reflectors are arranged such that the emitted light is reflected back toward the substrate and transmitted through the same in order to provide a uniform light distribution.
  • An object of at least some of the embodiments of the present invention is to provide an illumination device and an illumination system that are relatively low-cost and/or can be assembled with relative ease.
  • an illumination device having a light-transmitting substrate, or light guide, with a first surface and a second surface arranged opposite to each other.
  • a reflector with at least one at least partially reflective surface is facing the first surface of the light-transmitting substrate and at least one first light-emitting element is arranged such that at least some light emitted by the at least one first light-emitting element is in-coupled into the light-transmitting substrate via at least one edge of the same.
  • the at least one first light-emitting element and the light-transmitting substrate are arranged relatively to each other such that light emitted by the at least one first light emitting element that is in-coupled into the light-transmitting substrate is out-coupled from the light-transmitting substrate via the first surface.
  • the at least one at least partially reflective surface is arranged relatively to the first surface such that at least some of the light out-coupled from the first surface is reflected back towards the first surface, wherein the reflected light is out-coupled from the illumination device via the second surface.
  • an illumination system which comprises a first and a second illumination device in accordance with the first aspect of the invention. At least some of the light emitting elements of the first and second illumination devices are adjustable with respect to light output therefrom.
  • the illumination system comprises a controller that is adapted to control light output from the at least some of the light-emitting elements of the first and second illumination devices independently of each other.
  • the illumination system may comprise one or more additional illumination devices other than the first and second illumination devices, the light output of which additional illumination device or devices may also be independently controlled.
  • the illumination system may comprise only one illumination device.
  • the at least one first light- emitting element is arranged at the side of the light-transmitting substrate, and the generated light is coupled into the substrate via an edge of the substrate.
  • the light-emitting elements are arranged on the surface of the substrate that faces the reflector. This arrangement may require electrical interconnections arranged on the surface of the substrate for electrically connecting the light-emitting elements.
  • the risk for a non-uniform light distribution is increased due to shadowing.
  • Arranging and electrically connecting the light-emitting elements on the surface may also be time-consuming during assemblage of the device.
  • the present invention is advantageous in that it allows for the light-emitting elements to be mounted at the side of the light-transmitting substrate or at an edge thereof such that the light-emitting elements and their respective electrical connections do not shadow portions of the first surface of the substrate. Coupling the light into an edge of the substrate also facilitates assemblage of the device. Since the first and second surfaces of the light-transmitting substrate may be substantially or entirely free from any mounted light- emitting sources and electrical connectors, the risk of shadowing the transmitted light may be reduced or even eliminated. It also allows for a reduction of the number of components that need to be handled during assemblage, since the light-emitting elements can be arranged in a separate unit that easily can be attached to the edge of the substrate during assemblage.
  • the present invention is also advantageous in that the reflectors allow for a rather homogeneous light output having a reduced spottiness due to the light generated by the first light-emitting element or elements being spread by the reflector. Spreading the light such that the light output is distributed over a surface may also limit the peak intensity or brightness of the output light.
  • the light-transmitting substrate material may advantageously be chosen such that the substrate can dissipate heat generated by the light-emitting elements and allows for a transmission of light.
  • light-transmitting substrate it should be understood a substrate that comprises at least a portion that may be transparent or translucent, or comprises at least one portion that is transparent and at least one portion that is translucent.
  • the light- transmitting substrate may comprise at least a portion of a light scattering, or diffusive, material.
  • Examples of light transmitting materials include light-transmitting ceramics, such as e.g. glass and crystals, and ditto polymers, such as poly(methyl methacrylate) (PMMA), polycarbonate, and silicon rubber.
  • PMMA poly(methyl methacrylate)
  • the light-transmitting substrate may for example be a molded or extruded sheet.
  • the reflector may comprise an opaque or transparent material, such as a plastic material that advantageously may be shaped via for example injection molding or plastics-deformation processes. Thereby a relatively cost-effective production process may be achieved.
  • a reflective surface may be obtained by adding a specular or diffusive coating to the material.
  • the at least one at least partially reflective surface of the reflector may be arranged such that it is aligned with the portion of the first surface through which the light is out-coupled to the reflector.
  • the output light may be adjusted with regard to e.g. beam shape and uniformity.
  • light-emitting element is used to define any device or element that is capable of emitting radiation in any region or combination of regions of the
  • a light-emitting element can have monochromatic, quasi- monochromatic, polychromatic or broadband spectral emission characteristics.
  • Each light- emitting element has at least one light source. Examples of light sources include
  • RGB LEDs may advantageously be used to enable dynamic color light output from the illumination device.
  • the term light-emitting element can be used to define a combination of the specific light source that emits the radiation in combination with a housing or package within which the specific light source or light sources are placed.
  • the term light emitting element may comprise a bare LED die arranged in a housing, which may be referred to as a LED package.
  • the illumination device e.g. the light- transmitting substrate
  • the illumination device may comprise at least one light out-coupling structure that is adapted to extract light that impinge upon the at least one light out-coupling structure from within the light-transmitting substrate such that at least some of the impinging light exits via the first surface of the light-transmitting substrate.
  • Such light out-coupling structures are for instance comprised of embedded light scattering and/or reflecting particles, scratches, molded microstructures, or transparent components that are arranged within the light-transmitting substrate, such as on an inner surface, or arranged on an outer surface of the substrate by e.g. gluing.
  • the light out-coupling structures may be comprised of reflective spots that for instance are printed on the substrate.
  • the light out-coupling structures are able to extract light that impinge upon them from within the light-transmitting substrate such that it exits via the first surface of the substrate.
  • the light out-coupling structures and/or the areas of the first surface of the light-transmitting substrate through which light exits from the substrate may comprise a region that includes fluorescent phosphor arranged to modify wavelength of light impinging thereon or passing therethrough. This is advantageous if the light-emitting element is or includes for example a blue LED.
  • the illumination device may comprise a light scattering layer or element that is arranged to scatter the light that is out-coupled from the second surface of the light-transmitting substrate.
  • the light scattering, or diffusive layer is advantageous in that it may increase the homogeneity and prevent or reduce the risk of a viewer looking straight back into the light source, and thus reduce intensity.
  • the light scattering layer may for example comprise sand blasted glass or a diffuser foil that is integrated with the light-transmitting substrate, which thereby may enable for compact illumination devices to be obtained.
  • the light scattering layer may be arranged at a distance from the second surface of the light-transmitting substrate. This may reduce any shadows that may be visible on the light-transmitting substrate and may improve the uniformity of the illumination.
  • the light scattering layer may be arranged so as to allow for heat generated by the light emitting element to be dissipated e.g. by means of convection, which advantageously may lower the power consumption and increase the lifetime of the illumination device.
  • the illumination device comprises a reflector having at least one at least partially reflective surface.
  • at least a portion of the reflective surface is specular or diffusive, or a combination thereof.
  • a diffusive surface of the reflective surface may prevent or reduce the risk of a viewer looking back straight into the light source due to scattering of the light emitted by the illumination device.
  • At least a portion of the reflector has a tapered, parabolic, hyperbolic, or spherical shape, or a combination thereof.
  • the shape of the light beam as emitted by the illumination device may depend on the shape of the reflector which may be chosen such that a specific, predetermined beam shape is obtained.
  • the shape of the reflector may for example be determined by use of optical modeling software, such as LightTools®.
  • the reflector comprises a plurality of interconnected reflector segments, each comprising an at least partially reflective surface facing the first surface of the light-transmitting substrate.
  • Interconnected reflector segments are advantageous in that they may allow for various configurations in which the reflector segments for example may be connected in one-dimensional arrays or a two-dimensional lattice, etc., which may cover the whole surface of the light-transmitting substrate.
  • the illumination device may comprise a reflector segment wherein the periphery of the reflector segment has a shape that is one of a circle, oval, or a polygon.
  • the reflector may comprise a region that includes fluorescent phosphor arranged to modify wavelength of light impinging thereon.
  • the light-emitting element is for example a blue LED.
  • the region of the reflector may be coated with a continuous pattern, or provided with e.g. a dotted pattern. This is advantageous in that it allows for part of the light that is emitted by the light emitting element to be absorbed by the phosphor layer and re-emitted as light of a different wavelength. A mix of different wavelengths may thus be obtained, thereby allowing fine- tuning of the spectrum of light emitted by the illumination device as a whole.
  • the illumination device may comprise at least one second light-emitting element arranged on the first surface of the light-transmitting substrate.
  • the second light-emitting element may be adapted to emit light towards the reflector, wherein the light is reflected back towards the first surface and coupled out from the illumination device via the second surface.
  • the illumination device may comprise an electrically conductive pattern arranged on the first surface of the light-transmitting substrate in order to electrically connect the first and/or second light-emitting element.
  • the electrically conductive pattern may for example comprise electrical connectors including e.g. sintered silver paste which may be printed directly on the light-transmitting substrate, which advantageously may reduce the need for a more complicated coating and etching process.
  • the electrical connectors may also be applied to a carrier, such as for example a foil, which in turn can be laminated on the light- transmitting substrate. This is advantageous in that application of the electrical connectors by lamination may facilitate the production process, at least as compared with printing or coating and etching directly on the light-transmitting substrate.
  • the electrically conductive pattern may comprise a translucent conductive material, which advantageously may reduce the risk of shadowing effects as the light is transmitted from the first surface to the second surface of the light-transmitting substrate.
  • translucent electric conductive materials include indium tin oxide and fluorine doped tin oxide.
  • the electrical conductive pattern may comprise metal wires that may be loose wires or formed as patterns in thin layer, for example by depositing copper or aluminum on the first surface of the light-transmitting substrate. Such metal wires are advantageous in that they may provide a relatively high electrical conductivity and low power dissipation.
  • the metal wires may for example be applied to the light-transmitting substrate by printing or lithography, or by laminating a pre-produced net, foil or mat on the light-transmitting substrate.
  • the controller of the illumination system may be adapted to switch on and off the at least some of the light-emitting elements of the first and second illumination devices independently of each other. This advantageously allows for a user to either only switch on the light-emitting elements of the first device, to only switch on the light-emitting elements of the second device, or to switch on the light-emitting elements of both the first and second devices.
  • the at least some of the light-emitting elements of the first and second illumination devices are adjustable with respect to brightness of the light emitted therefrom.
  • the controller may be adapted to adjust the brightness of light emitted from the at least some of the light-emitting elements of the first and second illumination devices independently of each other.
  • the first and second illumination devices may for example comprise light-emitting elements generating a light of a first and a second wavelength spectrum, respectively. Enabling a user to individually adjust the brightness of the respective light-emitting elements may advantageously allow for a fine-tuning of the wavelength spectrum of the light emitted by the illumination system as a whole.
  • the illumination system may comprise beam shape adaptation means arranged to adapt a beam shape of light output from the first illumination device and to adapt a beam shape of light output from the second illumination device.
  • the beam shape adaptation means may be arranged to adapt the beam shape of light output from the first illumination device independently of the adaptation of the beam shape of light output from the second illumination device. Allowing a different beam shape of the first illumination device compared to the second illumination device is advantageous in that it may provide an illumination system capable emitting light of various beam shape.
  • the beam shape adaptation means may for example comprise a refractive beam shaper, such as for example lenses, or reflective mirrors.
  • the beam shape adaptation means may comprise micro-optic beam shapers such as optical fibres or arrays of small prisms.
  • an illumination system which comprises a first and a second illumination device in accordance with the first aspect of the invention.
  • the illumination system comprises beam shape adaptation means arranged to adapt a beam shape of light output from the first illumination device and to adapt a beam shape of light output from the second illumination device.
  • the beam shape adaptation means may be arranged to adapt the beam shape of light output from the first illumination device independently of the adaptation of the beam shape of light output from the second illumination device.
  • Figure 1 schematically depicts a cross sectional side view of an illumination device according to an embodiment of the present invention, comprising a light-emitting element arranged at a side of a light-transmitting substrate,
  • Figure 2 schematically depicts a cross sectional side view of an illumination device according to another embodiment of the present invention
  • Figure 3 schematically depicts a perspective view of an illumination device according to an embodiment of the present invention, the illumination device comprising a plurality of reflector segments,
  • Figure 4 schematically depict a top view of an illumination device according to another embodiment of the present invention.
  • FIG. 5 is a schematic block diagram of an illumination system, comprising a first and a second illumination device and a controller, according to an embodiment 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 the embodiments of the present invention, wherein other parts may be omitted or merely suggested. DETAILED DESCRIPTION
  • FIG. 1 and 2 there are shown a schematic cross sectional side views of illumination devices 100 according to embodiments of the present invention. Various configurations of the illumination device 100 are shown in Figures 1 and 2.
  • the illumination device 100 comprises a light-transmitting substrate 110 having a first surface 120 and an opposing second surface 130.
  • the illumination device 100 also comprises a reflector 140 comprising a plurality of reflector segments 145 facing the first surface 120 of the light -transmitting substrate 110.
  • each of the plurality of reflector segments 145 comprises an at least partially reflective surface facing the first surface 120 of the light-transmitting substrate 110.
  • a first light emitting element 150 in the form of a light-emitting diode (LED) 150 is arranged at a side of the light-transmitting substrate 110 such that light emitted by the LED 150 is coupled into the light-transmitting substrate at an edge 160 of the substrate 110.
  • LED light-emitting diode
  • the illumination device 100 may comprise a diffuser 180 of sand blasted glass arranged at a distance from the second surface 130 and arranged such that an air channel 190 is defined between the light-transmitting substrate 110 and the diffuser 180.
  • the air channel 190 may allow for heat generated by the LED 150 to be dissipated by an air flow through the air channel 190.
  • the light-transmitting substrate 110 shown in Figure 1 is arranged to receive input light through or via a light in-coupling surface 160 and to out-couple the light through or via the second surface 130.
  • the light-transmitting substrate 110 may be substantially plate shaped, having edge surfaces along its edges, as well as a top surface, or first surface, 120, and a bottom surface, or second surface, 130.
  • the light in-coupling surface 160 is arranged on at least one edge of the light-transmitting substrate 110 and is perpendicular to the top and bottom surfaces 120, 130.
  • the light- transmitting substrate 110 may alternatively be arranged in various other ways, such as having a curved configuration, having curved top and bottom surfaces 120, 130, be triangular, circular or have any other regular or irregular shape.
  • the light-transmitting substrate 110 is arranged to enable propagation of light coupled into it by means of total internal reflection (TIR).
  • TIR total internal reflection
  • substrate 110 comprises a material through which light can propagate, such as e.g. a transparent material.
  • a transparent material examples include transparent acrylic materials such as poly(methyl methacrylate) (PMMA), polycarbonate, glass and silicon rubber.
  • PMMA poly(methyl methacrylate)
  • PMMA poly(methyl methacrylate)
  • the light-transmitting substrate 110 is provided with light out-coupling structures 170, comprising light reflecting and/or scattering particles embedded in the substrate 110 and arranged such that light that impinges upon the light reflecting and/or scattering particles is redirected such that at least some of the light is redirected towards the first surface 120 at an angle of incidence that is smaller than the critical angle for TIR.
  • the light is enabled to be out-coupled from the first surface 120 of the light-transmitting substrate 110.
  • At least a part of the light that is out-coupled from the first surface 120 is impinging on the reflector 140, which in general comprises at least one at least partially reflective surface, e.g. having a specular portion.
  • Figure 1 shows an array of adjacently arranged parabolic reflector segments 145 having a circular periphery and arranged such that a centre of the circular periphery is aligned with the light out-coupling structures 170.
  • the reflective surface of the reflector segments 145 may have a diffusive portion and/or a portion coated with fluorescent phosphor.
  • the diffuser 180 is arranged such that the light that is out-coupled from the second surface 130 passes through the diffuser 180, whereby the light is scattered before being out-coupled from the illumination device 100.
  • the diffuser 180 may cover an area corresponding to the second surface 130, or at least a portion of the same.
  • the diffuser 180 may be laminated directly on the second surface 130 or, as depicted in Figure 1, arranged at a distance from the substrate 110 such that an air channel 190 is defined between the light transmitting substrate 110 and the diffuser 180.
  • the diffuser 180 comprises a glass sheet that has been sand blasted, but may in alternative or additionally comprise any other surface or material that enables a scattering of the light.
  • the air channel 190 is defined by the diffuser 180 and the second surface 130 of the substrate 110 which are arranged at such a distance from each other that heat generated by the LED 150 is allowed to be dissipated by means of convection.
  • an illumination device 100 similar to the illumination device 100 as described with reference to Figure 1 is depicted.
  • the illumination device 100 depicted in Figure 2 differs from the illumination device 100 depicted in Figure 1 in that the light out-coupling structures comprises molded micro-structures 175 that are arranged such that they protrude from the first surface 120 of the substrate 110.
  • the protruding molded micro-structures 175 are integrally formed with the light-transmitting substrate 110 and enable the light travelling within the light-transmitting substrate 110 by means of TIR to be out-coupled from the light-transmitting substrate 110 toward the reflector 140 as the light impinges on a surface of the protruding molded micro- structures 175.
  • the illumination device 100 comprises second light-emitting elements 155 arranged on the first surface 120 of the light-transmitting substrate 110, which are electrically connected by an electrically conductive pattern in the form of a translucent conductive layer 157 and adapted to emit light that impinges on the reflector segments 145.
  • the second light-emitting elements may for example comprise LEDs.
  • the reflected light emitted by the second light-emitting elements 155 is in-coupled via the first surface 120 of the light -transmitting substrate 110, transmitted through the light- transmitting substrate 110, and out-coupled via the second surface 130 of the light- transmitting substrate 110.
  • Figure 3 illustrates a schematic view of an illumination device 300 comprising a light-transmitting, substantially plate shaped substrate 310 having a rectangular shape according to an embodiment of the present invention.
  • the substrate 310 comprises a first surface and a second surface arranged opposite to the first surface, similarly as for the illumination devices 100 described with reference to Figures 1 and 2.
  • Light-emitting elements 350 are arranged in two separate units 355 at respective edges of the substrate 310 such that light emitted by the light-emitting elements 350 is in-coupled into the substrate 310.
  • a plurality of reflector segments 345 are arranged on the first surface of the substrate 310 and adjacent to each other such that a honeycomb pattern is formed, as illustrated in Figure 3.
  • the plurality of reflector segments 345 faces the first surface of the substrate 310.
  • the light emitted by the light-emitting elements 350 is in-coupled into the light-transmitting substrate 310 via its edges, and then travels inside the substrate 310.
  • Light out-coupling structures (not shown in Figure 3) are arranged in the substrate 310 such that they couple out light via the first surface of the substrate 310 at positions that correspond to the circumferential centre of each reflector segment 345.
  • At least a part of the light having been coupled out by the light out-coupling structures via the first surface of the substrate 310 is then reflected by the reflector segments 345 back towards the substrate 310 where the reflected light is in-coupled via the first surface and then travels through the substrate 310 towards the second surface, where light that impinges on the second surface at an angle of incidence that is smaller than the critical angle for TIR is enabled to be out-coupled through or via the second surface, whereby light is out-coupled from the illumination device 300.
  • the light out-coupling structures being arranged in the substrate 310 such that they couple out light via the first surface of the substrate 310 at positions that correspond to the
  • each reflector segment 345 a relatively homogeneous light distribution of the light emitted by the illumination device 300 may be achieved.
  • Other configurations are also possible, wherein the light is out-coupled via the first surface at other positions that are not aligned with the centre of the reflector segments 345, thereby enabling other beam shapes of the emitted light.
  • a light scattering layer e.g. a diffuser (not shown in Figure 3), may be arranged on, or at a distance from, the second surface of the substrate 310 in order to spread the light emitted by the illumination device 300.
  • the illumination device 300 may comprise beam shape adaptation means (not shown in Figure 3) for example comprising arrays of relatively small prisms.
  • the prisms are arranged to adapt a beam shape of the light output from the illumination device 300 e.g. so as to comply with a desired or predefined beam shape requirement.
  • an illumination device 400 according to another embodiment of the present invention.
  • the illumination device 400 is configured similarly to the illumination device 300 described with reference to Figure 3, and the operation of the illumination device 400 is similar to the illumination device 300 described with reference to Figure 3.
  • the illumination device 400 differs from the illumination device 300 described with reference to Figure 3 in that the illumination device 400 has reflector segments 445 with a triangular periphery.
  • segments 445 are arranged adjacent to each other in parallel rows arranged on the light- transmitting substrate 410. Furthermore, in the illumination device 400, two light-emitting elements 450 are arranged at an edge of the light-transmitting substrate 410, thereby enabling light to be in-coupled into the light-transmitting substrate 410.
  • FIG. 5 is a schematic block diagram of an illumination system 500 according to an embodiment of the present invention.
  • the illumination system 500 comprises a first illumination device 502 and a second illumination device 504 according to embodiments of the present invention and a controller 506.
  • Each of the first illumination device 502 and the second illumination device 504 may for example be configured according to any one of the embodiments described in the foregoing with reference to Figures 1-4.
  • Each of the first and the second illumination devices 502, 504 comprises at least one light-emitting element.
  • Each light-emitting element of the first and second illumination devices 502, 504 may be adapted to emit light having a certain wavelength or being within a certain wavelength interval. At least some of the light emitting elements of the first and second illumination devices 502, 504 are adjustable with respect to light output therefrom, e.g. with respect to the brightness of emitted light.
  • the controller 506 is adapted to control or adjust light output from the at least some of the light-emitting elements of the first and second illumination devices 502, 504 independently of each other.
  • the controller 506 may for example be adapted to control or adjust the brightness of the light emitted from the at least some of the light-emitting elements of the first and second illumination devices independently of each other, and/or to switch on and off the at least some of the light-emitting elements of the first and second illumination devices 502, 504 independently of each other.
  • a user may therefore use the controller 506 e.g. for switching on the light-emitting elements of only the first illumination device 502 or only the second illumination device 504, or for switching on the light-emitting elements of both the first and second illumination devices 502, 504.
  • the controller 506 may be used for adjusting the brightness of the light emitted by the at least some of the light-emitting elements of the first and second illumination devices 502, 504 such that the light output of the illumination system 500 as a whole can be fine-tuned with respect to e.g. brightness or wavelength spectrum of the emitted light.
  • the illumination system 500 comprises a beam shape adaptation means 508, which is optional, that is arranged to adapt a beam shape of light output from the first illumination device 502 and to adapt a beam shape of light output from the second illumination device 504.
  • the beam shape adaptation means 508 is arranged to adapt the beam shape of light output from the first illumination device 502 independently of the adaptation of the beam shape of light output from the second illumination device 504. By such beam shape adaptation means 508 the light emitted from the illumination system 500 may be spread in order to increase the homogeneity of the light output from the illumination system 500 as a whole.
  • an illumination device comprises a light-transmitting substrate having a first surface and a second surface arranged opposite to each other, a reflector facing the first surface of the light-transmitting substrate, and a first light-emitting element arranged such that light emitted by the first light-emitting element is coupled into at least one edge, or side edge, of the light-transmitting substrate.
  • the first light-emitting element and the light-transmitting substrate are arranged relatively to each other such that light emitted by the first light emitting element that is coupled into the light- transmitting substrate is coupled out from the light-transmitting substrate via the first surface.
  • the reflector is arranged relatively to the first surface such that light coupled out from the first surface is reflected back towards the first surface, wherein the reflected light is coupled out from the illumination device via the second surface.
  • An illumination system comprising the illumination device is also disclosed.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)

Abstract

An illumination device (100) is disclosed, comprising a light-transmitting substrate (110) having a first surface (120) and a second surface (130) arranged opposite to each other, a reflector (140) facing the first surface of the light-transmitting substrate, and a first light-emitting element (150) arranged such that light emitted by the first light-emitting element is coupled into an edge (160) of the light-transmitting substrate. The first light- emitting element and the light-transmitting substrate are arranged relatively to each other such that light emitted by the first light emitting element that is coupled into the light- transmitting substrate is coupled out from the light-transmitting substrate via the first surface. The reflector is arranged relatively to the first surface such that light coupled out from the first surface is reflected back towards the first surface, wherein the reflected light is coupled out from the illumination device via the second surface. An illumination system comprising the illumination device (1) is also disclosed.

Description

Illumination device and illumination system comprising an illumination device
FIELD OF THE INVENTION
The present invention relates to an illumination device wherein the light generated by at least one light-emitting element arranged at a side or sides of a light- transmitting substrate travels through the light-transmitting substrate. The present invention also relates to an illumination system comprising a first and a second illumination device and a controller for controlling the light output from the first and second illumination devices.
BACKGROUND OF THE INVENTION
Illumination devices emitting light that is comfortable to the eyes, by having e.g. homogeneous output light and a limited peak brightness and glare, are of interest for various lighting purposes, including applications such as office lights, shop lights, shop window lights, and illumination of public places and industry spaces.
In for example US 2006/0157724, a backlight device having a transparent substrate is described, wherein light emitting elements are arranged on an upper surface of a transparent substrate. Reflectors are arranged such that the emitted light is reflected back toward the substrate and transmitted through the same in order to provide a uniform light distribution.
Although such a device may provide a uniform light distribution and reduced glare, there is still a need for relatively low-cost devices that are easy to assemble and yet provide a light output that is comfortable to the eye.
SUMMARY OF THE INVENTION
An object of at least some of the embodiments of the present invention is to provide an illumination device and an illumination system that are relatively low-cost and/or can be assembled with relative ease.
At least one of this and other objects of the present invention is achieved by means of an illumination device and an illumination system having the features defined in the independent claims. Preferable embodiments of the invention are characterized by the dependent claims. According to a first aspect of the present invention, an illumination device is provided, having a light-transmitting substrate, or light guide, with a first surface and a second surface arranged opposite to each other. A reflector with at least one at least partially reflective surface is facing the first surface of the light-transmitting substrate and at least one first light-emitting element is arranged such that at least some light emitted by the at least one first light-emitting element is in-coupled into the light-transmitting substrate via at least one edge of the same. The at least one first light-emitting element and the light-transmitting substrate are arranged relatively to each other such that light emitted by the at least one first light emitting element that is in-coupled into the light-transmitting substrate is out-coupled from the light-transmitting substrate via the first surface. The at least one at least partially reflective surface is arranged relatively to the first surface such that at least some of the light out-coupled from the first surface is reflected back towards the first surface, wherein the reflected light is out-coupled from the illumination device via the second surface.
According to a second aspect of the present invention, an illumination system is provided, which comprises a first and a second illumination device in accordance with the first aspect of the invention. At least some of the light emitting elements of the first and second illumination devices are adjustable with respect to light output therefrom. The illumination system comprises a controller that is adapted to control light output from the at least some of the light-emitting elements of the first and second illumination devices independently of each other. The illumination system may comprise one or more additional illumination devices other than the first and second illumination devices, the light output of which additional illumination device or devices may also be independently controlled. The illumination system may comprise only one illumination device.
In the illumination device of the present invention, the at least one first light- emitting element is arranged at the side of the light-transmitting substrate, and the generated light is coupled into the substrate via an edge of the substrate.
In the device disclosed in US 2006/0157724, the light-emitting elements are arranged on the surface of the substrate that faces the reflector. This arrangement may require electrical interconnections arranged on the surface of the substrate for electrically connecting the light-emitting elements. However, by arranging light-emitting elements and electrical interconnections on the surface of the light-transmitting substrate, the risk for a non-uniform light distribution is increased due to shadowing. Arranging and electrically connecting the light-emitting elements on the surface may also be time-consuming during assemblage of the device. The present invention is advantageous in that it allows for the light-emitting elements to be mounted at the side of the light-transmitting substrate or at an edge thereof such that the light-emitting elements and their respective electrical connections do not shadow portions of the first surface of the substrate. Coupling the light into an edge of the substrate also facilitates assemblage of the device. Since the first and second surfaces of the light-transmitting substrate may be substantially or entirely free from any mounted light- emitting sources and electrical connectors, the risk of shadowing the transmitted light may be reduced or even eliminated. It also allows for a reduction of the number of components that need to be handled during assemblage, since the light-emitting elements can be arranged in a separate unit that easily can be attached to the edge of the substrate during assemblage.
The present invention is also advantageous in that the reflectors allow for a rather homogeneous light output having a reduced spottiness due to the light generated by the first light-emitting element or elements being spread by the reflector. Spreading the light such that the light output is distributed over a surface may also limit the peak intensity or brightness of the output light.
The light-transmitting substrate material may advantageously be chosen such that the substrate can dissipate heat generated by the light-emitting elements and allows for a transmission of light. By the term "light-transmitting substrate" it should be understood a substrate that comprises at least a portion that may be transparent or translucent, or comprises at least one portion that is transparent and at least one portion that is translucent. The light- transmitting substrate may comprise at least a portion of a light scattering, or diffusive, material. Examples of light transmitting materials include light-transmitting ceramics, such as e.g. glass and crystals, and ditto polymers, such as poly(methyl methacrylate) (PMMA), polycarbonate, and silicon rubber. The light-transmitting substrate may for example be a molded or extruded sheet.
The reflector may comprise an opaque or transparent material, such as a plastic material that advantageously may be shaped via for example injection molding or plastics-deformation processes. Thereby a relatively cost-effective production process may be achieved. In case the reflector comprises a transparent material, a reflective surface may be obtained by adding a specular or diffusive coating to the material.
The at least one at least partially reflective surface of the reflector may be arranged such that it is aligned with the portion of the first surface through which the light is out-coupled to the reflector. By adjusting the alignment of the at least one at least partially reflective surface of the reflector in relation to the portion of the first surface, the output light may be adjusted with regard to e.g. beam shape and uniformity.
The term "light-emitting element" is used to define any device or element that is capable of emitting radiation in any region or combination of regions of the
electromagnetic spectrum, for example the visible region, the infrared region, and/or the ultraviolet region, when activated e.g. by applying a potential difference across it or passing a current through it. Therefore a light-emitting element can have monochromatic, quasi- monochromatic, polychromatic or broadband spectral emission characteristics. Each light- emitting element has at least one light source. Examples of light sources include
semiconductor, organic, or polymer/polymeric light-emitting diodes (LEDs), blue 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. RGB LEDs may advantageously be used to enable dynamic color light output from the illumination device. Furthermore, the term light-emitting element can be used to define a combination of the specific light source that emits the radiation in combination with a housing or package within which the specific light source or light sources are placed. For example, the term light emitting element may comprise a bare LED die arranged in a housing, which may be referred to as a LED package.
According to an embodiment, the illumination device, e.g. the light- transmitting substrate, may comprise at least one light out-coupling structure that is adapted to extract light that impinge upon the at least one light out-coupling structure from within the light-transmitting substrate such that at least some of the impinging light exits via the first surface of the light-transmitting substrate. Such light out-coupling structures are for instance comprised of embedded light scattering and/or reflecting particles, scratches, molded microstructures, or transparent components that are arranged within the light-transmitting substrate, such as on an inner surface, or arranged on an outer surface of the substrate by e.g. gluing. The light out-coupling structures may be comprised of reflective spots that for instance are printed on the substrate. The light out-coupling structures are able to extract light that impinge upon them from within the light-transmitting substrate such that it exits via the first surface of the substrate.
The light out-coupling structures and/or the areas of the first surface of the light-transmitting substrate through which light exits from the substrate may comprise a region that includes fluorescent phosphor arranged to modify wavelength of light impinging thereon or passing therethrough. This is advantageous if the light-emitting element is or includes for example a blue LED.
According to an embodiment, the illumination device may comprise a light scattering layer or element that is arranged to scatter the light that is out-coupled from the second surface of the light-transmitting substrate. The light scattering, or diffusive layer is advantageous in that it may increase the homogeneity and prevent or reduce the risk of a viewer looking straight back into the light source, and thus reduce intensity. The light scattering layer may for example comprise sand blasted glass or a diffuser foil that is integrated with the light-transmitting substrate, which thereby may enable for compact illumination devices to be obtained.
According to another embodiment, the light scattering layer may be arranged at a distance from the second surface of the light-transmitting substrate. This may reduce any shadows that may be visible on the light-transmitting substrate and may improve the uniformity of the illumination.
According to yet another embodiment, the light scattering layer may be arranged so as to allow for heat generated by the light emitting element to be dissipated e.g. by means of convection, which advantageously may lower the power consumption and increase the lifetime of the illumination device.
The illumination device comprises a reflector having at least one at least partially reflective surface. According to an embodiment, at least a portion of the reflective surface is specular or diffusive, or a combination thereof. A diffusive surface of the reflective surface may prevent or reduce the risk of a viewer looking back straight into the light source due to scattering of the light emitted by the illumination device.
According to an embodiment, at least a portion of the reflector has a tapered, parabolic, hyperbolic, or spherical shape, or a combination thereof. The shape of the light beam as emitted by the illumination device may depend on the shape of the reflector which may be chosen such that a specific, predetermined beam shape is obtained. The shape of the reflector may for example be determined by use of optical modeling software, such as LightTools®.
According to an embodiment, the reflector comprises a plurality of interconnected reflector segments, each comprising an at least partially reflective surface facing the first surface of the light-transmitting substrate. Interconnected reflector segments are advantageous in that they may allow for various configurations in which the reflector segments for example may be connected in one-dimensional arrays or a two-dimensional lattice, etc., which may cover the whole surface of the light-transmitting substrate.
According to an embodiment, the illumination device may comprise a reflector segment wherein the periphery of the reflector segment has a shape that is one of a circle, oval, or a polygon.
According to an embodiment, the reflector may comprise a region that includes fluorescent phosphor arranged to modify wavelength of light impinging thereon. This is advantageous if the light-emitting element is for example a blue LED. The region of the reflector may be coated with a continuous pattern, or provided with e.g. a dotted pattern. This is advantageous in that it allows for part of the light that is emitted by the light emitting element to be absorbed by the phosphor layer and re-emitted as light of a different wavelength. A mix of different wavelengths may thus be obtained, thereby allowing fine- tuning of the spectrum of light emitted by the illumination device as a whole.
According to an embodiment, the illumination device may comprise at least one second light-emitting element arranged on the first surface of the light-transmitting substrate. The second light-emitting element may be adapted to emit light towards the reflector, wherein the light is reflected back towards the first surface and coupled out from the illumination device via the second surface.
The illumination device may comprise an electrically conductive pattern arranged on the first surface of the light-transmitting substrate in order to electrically connect the first and/or second light-emitting element. The electrically conductive pattern may for example comprise electrical connectors including e.g. sintered silver paste which may be printed directly on the light-transmitting substrate, which advantageously may reduce the need for a more complicated coating and etching process. The electrical connectors may also be applied to a carrier, such as for example a foil, which in turn can be laminated on the light- transmitting substrate. This is advantageous in that application of the electrical connectors by lamination may facilitate the production process, at least as compared with printing or coating and etching directly on the light-transmitting substrate.
The electrically conductive pattern may comprise a translucent conductive material, which advantageously may reduce the risk of shadowing effects as the light is transmitted from the first surface to the second surface of the light-transmitting substrate. Examples of translucent electric conductive materials include indium tin oxide and fluorine doped tin oxide. The electrical conductive pattern may comprise metal wires that may be loose wires or formed as patterns in thin layer, for example by depositing copper or aluminum on the first surface of the light-transmitting substrate. Such metal wires are advantageous in that they may provide a relatively high electrical conductivity and low power dissipation. The metal wires may for example be applied to the light-transmitting substrate by printing or lithography, or by laminating a pre-produced net, foil or mat on the light-transmitting substrate.
According to an embodiment, the controller of the illumination system may be adapted to switch on and off the at least some of the light-emitting elements of the first and second illumination devices independently of each other. This advantageously allows for a user to either only switch on the light-emitting elements of the first device, to only switch on the light-emitting elements of the second device, or to switch on the light-emitting elements of both the first and second devices.
According to another embodiment, the at least some of the light-emitting elements of the first and second illumination devices are adjustable with respect to brightness of the light emitted therefrom. The controller may be adapted to adjust the brightness of light emitted from the at least some of the light-emitting elements of the first and second illumination devices independently of each other. The first and second illumination devices may for example comprise light-emitting elements generating a light of a first and a second wavelength spectrum, respectively. Enabling a user to individually adjust the brightness of the respective light-emitting elements may advantageously allow for a fine-tuning of the wavelength spectrum of the light emitted by the illumination system as a whole.
According to an embodiment, the illumination system may comprise beam shape adaptation means arranged to adapt a beam shape of light output from the first illumination device and to adapt a beam shape of light output from the second illumination device. The beam shape adaptation means may be arranged to adapt the beam shape of light output from the first illumination device independently of the adaptation of the beam shape of light output from the second illumination device. Allowing a different beam shape of the first illumination device compared to the second illumination device is advantageous in that it may provide an illumination system capable emitting light of various beam shape. The beam shape adaptation means may for example comprise a refractive beam shaper, such as for example lenses, or reflective mirrors. The beam shape adaptation means may comprise micro-optic beam shapers such as optical fibres or arrays of small prisms.
According to a third aspect of the present invention, an illumination system is provided, which comprises a first and a second illumination device in accordance with the first aspect of the invention. The illumination system comprises beam shape adaptation means arranged to adapt a beam shape of light output from the first illumination device and to adapt a beam shape of light output from the second illumination device. The beam shape adaptation means may be arranged to adapt the beam shape of light output from the first illumination device independently of the adaptation of the beam shape of light output from the second illumination device.
It will be appreciated that other embodiments than those described above are also possible. It will also be appreciated that any of the features in the embodiments described above for the illumination device according to the first aspect of the present invention may be combined with the illumination system according to the second or third aspect of the present invention. Further objectives of, features of, and advantages with the present invention will become apparent when studying the following detailed disclosure, the drawings, and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following.
BRIEF DESCRIPTION OF THE DRAWINGS
The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non- limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, in which:
Figure 1 schematically depicts a cross sectional side view of an illumination device according to an embodiment of the present invention, comprising a light-emitting element arranged at a side of a light-transmitting substrate,
Figure 2 schematically depicts a cross sectional side view of an illumination device according to another embodiment of the present invention,
Figure 3 schematically depicts a perspective view of an illumination device according to an embodiment of the present invention, the illumination device comprising a plurality of reflector segments,
Figure 4 schematically depict a top view of an illumination device according to another embodiment of the present invention, and
Figure 5 is a schematic block diagram of an illumination system, comprising a first and a second illumination device and a controller, according to an embodiment 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 the embodiments of the present invention, wherein other parts may be omitted or merely suggested. DETAILED DESCRIPTION
The present invention will now be described more fully 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 set forth herein; rather, these embodiments are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art. Furthermore, like numbers refer to the same or similar elements or components throughout.
With reference to Figures 1 and 2, there are shown a schematic cross sectional side views of illumination devices 100 according to embodiments of the present invention. Various configurations of the illumination device 100 are shown in Figures 1 and 2.
The illumination device 100 comprises a light-transmitting substrate 110 having a first surface 120 and an opposing second surface 130. The illumination device 100 also comprises a reflector 140 comprising a plurality of reflector segments 145 facing the first surface 120 of the light -transmitting substrate 110. According to the embodiments depicted in Figures 1 and 2, each of the plurality of reflector segments 145 comprises an at least partially reflective surface facing the first surface 120 of the light-transmitting substrate 110. A first light emitting element 150 in the form of a light-emitting diode (LED) 150 is arranged at a side of the light-transmitting substrate 110 such that light emitted by the LED 150 is coupled into the light-transmitting substrate at an edge 160 of the substrate 110. Optionally, the illumination device 100 may comprise a diffuser 180 of sand blasted glass arranged at a distance from the second surface 130 and arranged such that an air channel 190 is defined between the light-transmitting substrate 110 and the diffuser 180. The air channel 190 may allow for heat generated by the LED 150 to be dissipated by an air flow through the air channel 190.
The light-transmitting substrate 110 shown in Figure 1 is arranged to receive input light through or via a light in-coupling surface 160 and to out-couple the light through or via the second surface 130. The light-transmitting substrate 110 may be substantially plate shaped, having edge surfaces along its edges, as well as a top surface, or first surface, 120, and a bottom surface, or second surface, 130. According to the depicted embodiment, the light in-coupling surface 160 is arranged on at least one edge of the light-transmitting substrate 110 and is perpendicular to the top and bottom surfaces 120, 130. The light- transmitting substrate 110 may alternatively be arranged in various other ways, such as having a curved configuration, having curved top and bottom surfaces 120, 130, be triangular, circular or have any other regular or irregular shape.
The light-transmitting substrate 110 is arranged to enable propagation of light coupled into it by means of total internal reflection (TIR). The light-transmitting
substrate 110 comprises a material through which light can propagate, such as e.g. a transparent material. Examples of such materials include transparent acrylic materials such as poly(methyl methacrylate) (PMMA), polycarbonate, glass and silicon rubber. The arrows in Figures 1 and 2 indicate examples of paths of light rays traveling or propagating in the light- transmitting substrate 110.
According to the embodiment depicted in Figure 1 , the light-transmitting substrate 110 is provided with light out-coupling structures 170, comprising light reflecting and/or scattering particles embedded in the substrate 110 and arranged such that light that impinges upon the light reflecting and/or scattering particles is redirected such that at least some of the light is redirected towards the first surface 120 at an angle of incidence that is smaller than the critical angle for TIR. Thereby, the light is enabled to be out-coupled from the first surface 120 of the light-transmitting substrate 110.
At least a part of the light that is out-coupled from the first surface 120 is impinging on the reflector 140, which in general comprises at least one at least partially reflective surface, e.g. having a specular portion. Figure 1 shows an array of adjacently arranged parabolic reflector segments 145 having a circular periphery and arranged such that a centre of the circular periphery is aligned with the light out-coupling structures 170. The reflective surface of the reflector segments 145 may have a diffusive portion and/or a portion coated with fluorescent phosphor.
As light impinges upon the reflective surface of the reflector segments 145, at least a part of the light is reflected back towards the first surface 120 of the light-transmitting substrate 110, where at least some of the reflected light is in-coupled into the light- transmitting substrate 110. The reflected, in-coupled light then travels through the light- transmitting substrate 110 towards the second, bottom surface 130 where light that impinges on the second surface 130 at an angle of incidence that is smaller than the critical angle for TIR is enabled to be out-coupled through or via the second surface 130. The diffuser 180 is arranged such that the light that is out-coupled from the second surface 130 passes through the diffuser 180, whereby the light is scattered before being out-coupled from the illumination device 100. The diffuser 180 may cover an area corresponding to the second surface 130, or at least a portion of the same. The diffuser 180 may be laminated directly on the second surface 130 or, as depicted in Figure 1, arranged at a distance from the substrate 110 such that an air channel 190 is defined between the light transmitting substrate 110 and the diffuser 180. The diffuser 180 comprises a glass sheet that has been sand blasted, but may in alternative or additionally comprise any other surface or material that enables a scattering of the light.
The air channel 190 is defined by the diffuser 180 and the second surface 130 of the substrate 110 which are arranged at such a distance from each other that heat generated by the LED 150 is allowed to be dissipated by means of convection.
With reference to Figure 2, an illumination device 100 similar to the illumination device 100 as described with reference to Figure 1 is depicted. The illumination device 100 depicted in Figure 2 differs from the illumination device 100 depicted in Figure 1 in that the light out-coupling structures comprises molded micro-structures 175 that are arranged such that they protrude from the first surface 120 of the substrate 110. The protruding molded micro-structures 175 are integrally formed with the light-transmitting substrate 110 and enable the light travelling within the light-transmitting substrate 110 by means of TIR to be out-coupled from the light-transmitting substrate 110 toward the reflector 140 as the light impinges on a surface of the protruding molded micro- structures 175.
With further reference to Figure 2, the illumination device 100 comprises second light-emitting elements 155 arranged on the first surface 120 of the light-transmitting substrate 110, which are electrically connected by an electrically conductive pattern in the form of a translucent conductive layer 157 and adapted to emit light that impinges on the reflector segments 145. The second light-emitting elements may for example comprise LEDs. The reflected light emitted by the second light-emitting elements 155 is in-coupled via the first surface 120 of the light -transmitting substrate 110, transmitted through the light- transmitting substrate 110, and out-coupled via the second surface 130 of the light- transmitting substrate 110.
Figure 3 illustrates a schematic view of an illumination device 300 comprising a light-transmitting, substantially plate shaped substrate 310 having a rectangular shape according to an embodiment of the present invention. The substrate 310 comprises a first surface and a second surface arranged opposite to the first surface, similarly as for the illumination devices 100 described with reference to Figures 1 and 2. Light-emitting elements 350 are arranged in two separate units 355 at respective edges of the substrate 310 such that light emitted by the light-emitting elements 350 is in-coupled into the substrate 310. A plurality of reflector segments 345, each comprising an at least partially reflective surface and having a periphery shaped as a hexagon, are arranged on the first surface of the substrate 310 and adjacent to each other such that a honeycomb pattern is formed, as illustrated in Figure 3. However, other configurations and/or shapes of the reflector segments 345 may be contemplated according to application or user desires or requirements. The plurality of reflector segments 345 faces the first surface of the substrate 310.
The light emitted by the light-emitting elements 350 is in-coupled into the light-transmitting substrate 310 via its edges, and then travels inside the substrate 310. Light out-coupling structures (not shown in Figure 3) are arranged in the substrate 310 such that they couple out light via the first surface of the substrate 310 at positions that correspond to the circumferential centre of each reflector segment 345. At least a part of the light having been coupled out by the light out-coupling structures via the first surface of the substrate 310 is then reflected by the reflector segments 345 back towards the substrate 310 where the reflected light is in-coupled via the first surface and then travels through the substrate 310 towards the second surface, where light that impinges on the second surface at an angle of incidence that is smaller than the critical angle for TIR is enabled to be out-coupled through or via the second surface, whereby light is out-coupled from the illumination device 300. By the light out-coupling structures being arranged in the substrate 310 such that they couple out light via the first surface of the substrate 310 at positions that correspond to the
circumferential centre of each reflector segment 345, a relatively homogeneous light distribution of the light emitted by the illumination device 300 may be achieved. Other configurations are also possible, wherein the light is out-coupled via the first surface at other positions that are not aligned with the centre of the reflector segments 345, thereby enabling other beam shapes of the emitted light.
A light scattering layer, e.g. a diffuser (not shown in Figure 3), may be arranged on, or at a distance from, the second surface of the substrate 310 in order to spread the light emitted by the illumination device 300.
The illumination device 300 may comprise beam shape adaptation means (not shown in Figure 3) for example comprising arrays of relatively small prisms. The prisms are arranged to adapt a beam shape of the light output from the illumination device 300 e.g. so as to comply with a desired or predefined beam shape requirement.
With reference to Figure 4, there is shown an illumination device 400 according to another embodiment of the present invention. The illumination device 400 is configured similarly to the illumination device 300 described with reference to Figure 3, and the operation of the illumination device 400 is similar to the illumination device 300 described with reference to Figure 3. The illumination device 400 differs from the illumination device 300 described with reference to Figure 3 in that the illumination device 400 has reflector segments 445 with a triangular periphery. The reflector
segments 445 are arranged adjacent to each other in parallel rows arranged on the light- transmitting substrate 410. Furthermore, in the illumination device 400, two light-emitting elements 450 are arranged at an edge of the light-transmitting substrate 410, thereby enabling light to be in-coupled into the light-transmitting substrate 410.
Figure 5 is a schematic block diagram of an illumination system 500 according to an embodiment of the present invention. The illumination system 500 comprises a first illumination device 502 and a second illumination device 504 according to embodiments of the present invention and a controller 506. Each of the first illumination device 502 and the second illumination device 504 may for example be configured according to any one of the embodiments described in the foregoing with reference to Figures 1-4.
Each of the first and the second illumination devices 502, 504 comprises at least one light-emitting element. Each light-emitting element of the first and second illumination devices 502, 504 may be adapted to emit light having a certain wavelength or being within a certain wavelength interval. At least some of the light emitting elements of the first and second illumination devices 502, 504 are adjustable with respect to light output therefrom, e.g. with respect to the brightness of emitted light. The controller 506 is adapted to control or adjust light output from the at least some of the light-emitting elements of the first and second illumination devices 502, 504 independently of each other.
The controller 506 may for example be adapted to control or adjust the brightness of the light emitted from the at least some of the light-emitting elements of the first and second illumination devices independently of each other, and/or to switch on and off the at least some of the light-emitting elements of the first and second illumination devices 502, 504 independently of each other. A user may therefore use the controller 506 e.g. for switching on the light-emitting elements of only the first illumination device 502 or only the second illumination device 504, or for switching on the light-emitting elements of both the first and second illumination devices 502, 504. The controller 506 may be used for adjusting the brightness of the light emitted by the at least some of the light-emitting elements of the first and second illumination devices 502, 504 such that the light output of the illumination system 500 as a whole can be fine-tuned with respect to e.g. brightness or wavelength spectrum of the emitted light.
The illumination system 500 comprises a beam shape adaptation means 508, which is optional, that is arranged to adapt a beam shape of light output from the first illumination device 502 and to adapt a beam shape of light output from the second illumination device 504. The beam shape adaptation means 508 is arranged to adapt the beam shape of light output from the first illumination device 502 independently of the adaptation of the beam shape of light output from the second illumination device 504. By such beam shape adaptation means 508 the light emitted from the illumination system 500 may be spread in order to increase the homogeneity of the light output from the illumination system 500 as a whole.
In conclusion, an illumination device is disclosed. The illumination device comprises a light-transmitting substrate having a first surface and a second surface arranged opposite to each other, a reflector facing the first surface of the light-transmitting substrate, and a first light-emitting element arranged such that light emitted by the first light-emitting element is coupled into at least one edge, or side edge, of the light-transmitting substrate. The first light-emitting element and the light-transmitting substrate are arranged relatively to each other such that light emitted by the first light emitting element that is coupled into the light- transmitting substrate is coupled out from the light-transmitting substrate via the first surface. The reflector is arranged relatively to the first surface such that light coupled out from the first surface is reflected back towards the first surface, wherein the reflected light is coupled out from the illumination device via the second surface. An illumination system comprising the illumination device is also disclosed.
While the present invention has been illustrated and described in detail in the appended drawings and the foregoing description, such illustration and description are 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. 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. An illumination device (100), comprising:
a light-transmitting substrate (110) having a first surface (120) and a second surface (130) arranged opposite to each other,
a reflector (140) comprising at least one at least partially refiective surface facing the first surface of the light-transmitting substrate, and
at least one first light-emitting element (150) arranged such that at least some light emitted by the at least one first light-emitting element is coupled into at least one edge (160) of the light-transmitting substrate,
wherein the at least one first light-emitting element and the light-transmitting substrate are arranged relatively to each other such that light emitted by the at least one first light emitting element that is coupled into the light-transmitting substrate is coupled out from the light- transmitting substrate via the first surface, and
wherein the at least one at least partially reflective surface is arranged relatively to the first surface so as to reflect at least some of the light coupled out from the first surface back towards the first surface, wherein the reflected light is coupled out from the illumination device via the second surface.
2. The illumination device according to claim 1, wherein the light-transmitting substrate comprises at least one light out-coupling structure (170, 175) that is adapted to extract light that impinge upon the at least one light out-coupling structure from within the light-transmitting substrate such that at least some of the impinging light exits via the first surface of the light-transmitting substrate.
3. The illumination device according to any one of the preceding claims, wherein at least a portion of the light-transmitting substrate is transparent or translucent.
4. The illumination device according to any one of the preceding claims, wherein at least a portion of the at least one partially reflective surface is specular or diffusive, or a combination thereof.
5. The illumination device according to any one of the preceding claims, wherein at least a portion of the reflector has a tapered, parabolic, hyperbolic, or spherical shape, or a combination thereof.
6. The illumination device according to any one of the preceding claims, wherein the reflector comprises a plurality of interconnected reflector segments (145, 345, 445), wherein each of the plurality of reflector segments comprises an at least partially reflective surface facing the first surface of the light-transmitting substrate.
7. The illumination device according to claim 6, wherein the periphery of the at least one of the plurality of the reflector segments has a shape that is one of a circle, oval, or a polygon.
8. The illumination device according to any one of the preceding claims, wherein at least a portion of the at least one at least partially reflective surface comprises a region that includes fluorescent phosphor arranged to modify wavelength of light impinging thereon.
9. The illumination device according to any one of the preceding claims, further comprising at least one second light-emitting element (155) arranged on the first surface of the light-transmitting substrate, the at least one second light-emitting element being adapted to emit light towards the reflector, wherein the at least one at least partially reflective surface is arranged to reflect at least some of said light back towards the first surface, wherein the reflected light is coupled out from the illumination device via the second surface.
10. The illumination device according to claim 9, further comprising an electrically conductive pattern (157) arranged on the first surface of the light-transmitting substrate so as to electrically connect the at least one first light-emitting element and/or the at least one second light-emitting element.
11. The illumination device according to claim 10, wherein the electrically conductive pattern comprises a translucent conductive material.
12. An illumination system, comprising:
a first and a second illumination device (502, 504) according to any one of the preceding claims, and
a controller (506);
wherein at least some of the light emitting elements of the first and second illumination devices are adjustable with respect to light output therefrom, and the controller is adapted to control light output from the at least some of the light-emitting elements of the first and second illumination devices independently of each other.
13. The illumination system according to claim 12, wherein the controller is adapted to switch on and off the at least some of the light-emitting elements of the first and second illumination devices independently of each other.
14. The illumination system according to claim 12, wherein the at least some of the light-emitting elements of the first and second illumination devices are adjustable with respect to brightness of the light emitted therefrom, wherein the controller is adapted to adjust the brightness of light emitted from the at least some of the light-emitting elements of the first and second illumination devices independently of each other.
15. An illumination system, comprising:
a first and a second illumination device (502, 504) according to any one of claims 1-11; and
beam shape adaptation means (508) arranged to adapt a beam shape of light output from the first illumination device and to adapt a beam shape of light output from the second illumination device, wherein the beam shape adaptation means is arranged to adapt the beam shape of light output from the first illumination device independently of the adaptation of the beam shape of light output from the second illumination device.
PCT/IB2013/058869 2012-12-19 2013-09-26 Illumination device and illumination system comprising an illumination device WO2014096998A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201261739087P 2012-12-19 2012-12-19
US61/739,087 2012-12-19

Publications (1)

Publication Number Publication Date
WO2014096998A1 true WO2014096998A1 (en) 2014-06-26

Family

ID=49880847

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2013/058869 WO2014096998A1 (en) 2012-12-19 2013-09-26 Illumination device and illumination system comprising an illumination device

Country Status (1)

Country Link
WO (1) WO2014096998A1 (en)

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002258281A (en) * 2001-03-01 2002-09-11 Furuno Electric Co Ltd Liquid crystal display, luminance adjusting device and display device
US6608614B1 (en) * 2000-06-22 2003-08-19 Rockwell Collins, Inc. Led-based LCD backlight with extended color space
EP1533632A1 (en) * 2003-11-21 2005-05-25 Kabushiki Kaisha Toyota Jidoshokki Area light source apparatus and liquid crystal display
US20060157724A1 (en) 2004-12-21 2006-07-20 Yusuke Fujita Light-emitting diode, backlight device and method of manufacturing the light-emitting diode
US20070014110A1 (en) * 2005-07-12 2007-01-18 Nec Lcd Technologies, Ltd. Lighting unit and liquid crystal display device using the lighting unit
EP1801639A1 (en) * 2005-12-21 2007-06-27 Honeywell International, Inc. LED backlight system for LCD displays
US20090303411A1 (en) * 2006-06-21 2009-12-10 Idemitsu Kosan Co., Ltd. Multilayered sheet for light reflection, reflector, lighting unit and liquid crystal display device using the same
EP2372413A1 (en) * 2010-03-30 2011-10-05 Samsung LED Co., Ltd. Lighting apparatus
WO2012161212A1 (en) * 2011-05-23 2012-11-29 シャープ株式会社 Planar light-source device and manufacturing method for same, display device, and lighting device

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6608614B1 (en) * 2000-06-22 2003-08-19 Rockwell Collins, Inc. Led-based LCD backlight with extended color space
JP2002258281A (en) * 2001-03-01 2002-09-11 Furuno Electric Co Ltd Liquid crystal display, luminance adjusting device and display device
EP1533632A1 (en) * 2003-11-21 2005-05-25 Kabushiki Kaisha Toyota Jidoshokki Area light source apparatus and liquid crystal display
US20060157724A1 (en) 2004-12-21 2006-07-20 Yusuke Fujita Light-emitting diode, backlight device and method of manufacturing the light-emitting diode
US20070014110A1 (en) * 2005-07-12 2007-01-18 Nec Lcd Technologies, Ltd. Lighting unit and liquid crystal display device using the lighting unit
EP1801639A1 (en) * 2005-12-21 2007-06-27 Honeywell International, Inc. LED backlight system for LCD displays
US20090303411A1 (en) * 2006-06-21 2009-12-10 Idemitsu Kosan Co., Ltd. Multilayered sheet for light reflection, reflector, lighting unit and liquid crystal display device using the same
EP2372413A1 (en) * 2010-03-30 2011-10-05 Samsung LED Co., Ltd. Lighting apparatus
WO2012161212A1 (en) * 2011-05-23 2012-11-29 シャープ株式会社 Planar light-source device and manufacturing method for same, display device, and lighting device

Similar Documents

Publication Publication Date Title
US8789993B2 (en) Light-emitting device
US10209429B2 (en) Luminaire with selectable luminous intensity pattern
KR101203133B1 (en) Led lighting device
TWI390266B (en) Lighting system, vehicle headlights, projection systems, lamps, signal lights, displays, and methods of providing illumination
US8827531B2 (en) Lighting assembly
CN104115050B (en) Optical element for Uniform Illumination
CN104169633B (en) Surface light source
CN110260263B (en) Vehicle-mounted dual-function light emitting module and vehicle-mounted dual-function lighting lamp set
JP2009542017A5 (en)
JP2011508373A (en) Discrete light emitting element and planar assembly thereof
CN111025743B (en) Light source module and display device
EP2041485A1 (en) Waveguide with asymmetric outcoupling
KR20170115062A (en) White light source
CN104822986B (en) Use the light emitting device of light guide
JP2011159970A (en) Light emitting element package
JP6446202B2 (en) Wide-angle diffusion optical system and illumination device using the same
CN111509105A (en) Light-emitting element, light-emitting module and backlight module
CN111458925A (en) Light source module and display device
WO2012059866A1 (en) Light emitting sheet
US20150043243A1 (en) Lighting panel
KR20100108246A (en) Illumination device
KR101411218B1 (en) Lateral planar light emitting module
JP2012114081A (en) Glare-reduced lighting system
US20130272025A1 (en) Lighting device and cove lighting module using the same
WO2014096998A1 (en) Illumination device and illumination system comprising an illumination device

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13812079

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 13812079

Country of ref document: EP

Kind code of ref document: A1

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载