WO2008032275A1 - Luminaire à diodes électroluminescentes fin et plat - Google Patents

Luminaire à diodes électroluminescentes fin et plat Download PDF

Info

Publication number
WO2008032275A1
WO2008032275A1 PCT/IB2007/053675 IB2007053675W WO2008032275A1 WO 2008032275 A1 WO2008032275 A1 WO 2008032275A1 IB 2007053675 W IB2007053675 W IB 2007053675W WO 2008032275 A1 WO2008032275 A1 WO 2008032275A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
protrusions
emitting device
light emitting
array
Prior art date
Application number
PCT/IB2007/053675
Other languages
English (en)
Inventor
Hugo J. Cornelissen
Willem L. Ijzerman
Michel C. J. M. Vissenberg
Original Assignee
Koninklijke Philips Electronics 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 Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2008032275A1 publication Critical patent/WO2008032275A1/fr

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
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0018—Redirecting means on the surface of the light guide
    • 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
    • G02B6/0066—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 characterised by the light source being coupled to the light guide
    • G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources
    • 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
    • G02B6/0045—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 by shaping at least a portion of the light guide
    • G02B6/0046—Tapered light guide, e.g. wedge-shaped light guide
    • 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
    • G02B6/0053—Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Definitions

  • the present invention relates to a light-emitting device comprising a plurality of mutually spaced apart light emitting diodes arranged on a substrate, and a light guide plate.
  • luminaries should fulfill several requirements.
  • the light source should have a sufficiently long lifetime.
  • Conventional luminaries are often based on fluorescent tubes, which have a relatively limited lifetime.
  • the tubes themselves need to be replaced every 6000 hours. This corresponds to a replacement every 2 years, which adds to the cost of ownership.
  • the light output of the luminary should be robust against dust and other dirt.
  • a luminary that collects dust will become less efficient, since the dirt blocks light. Since cleaning the luminary is an expensive matter, the design should be robust against dust and dirt.
  • the luminary should satisfy an anti-glare requirement (i.e. the unified glare ratio should be sufficiently small).
  • This anti-glare requirement means that the luminary should not show any bright spots. In particular, there should be no bright spots if the luminary is viewed under an oblique angle.
  • a luminary of the prior art is disclosed in US 6 241 358, describing a lighting panel consisting of a set of light guide blocks in tandem arrangement, where a separate fluorescent tube provide light for each light guide block. The light from the fluorescent tubes is transmitted into the respective light guide block, is distributed therein and is transmitted through an output surface of the light guide block.
  • fluorescent tubes have a limited lifetime and are expensive to replace. Further, the breakdown of a single fluorescent tube in this prior art luminary has a drastic negative impact on the lighting capacity of the lighting panel and on the homogeneity of the light from the lighting panel. Thus, when one of the tubes breaks down, it will be necessary to replace this broken tube immediately. Further, fluorescent tubes emit a constant spectrum, which limits the color variability capacity of such a lighting panel.
  • the protrusions provide a light receiving face which transmits light from the light emitting diodes into said light guide plate, and a light reflection face which reflects light in said light guide plate, which light has a directional component along said general direction of light, towards said front surface.
  • the light from the plurality of LEDs will be transmitted into the light guide plate and will be distributed therein before exiting the light guide plate via the front side thereof.
  • the present invention provides a light-emitting device that provides well- distributed light from a plurality of point light sources.
  • light emitting diodes as primary light sources is advantageous as they have a long lifetime. Hence, service intervals will be extended, leading to a lower cost of ownership.
  • light emitting diodes are capable of emitting light of saturated colors, allowing the light-emitting device to produce light with high color- variability.
  • more than one light emitting diode may be located in a single space between two adjacent protrusions.
  • a plurality of LEDs arranged in such a single space may together form an extended light source, that will not fully be disfunctional in the case one or a few of the LEDs in that plurality of LEDs break down, since the neighboring LEDs will still be in operation.
  • a plurality of LEDs of different colors typically independently addressable, may be used in such a single space in order to provide a color variable light- emitting device.
  • reflective layers may be arranged at the back surface side of the reflection face of said protrusions of the first array. Such reflective layer increases the light utilization efficiency, since light exiting the light guide plate via the back surface can be reflected back towards the front surface. Further, it prevents light to be transmitted into the light guide plate via the reflection faces.
  • the substrate on which the LEDs are arranged comprises a plurality of mutually spaced apart recesses, and the substrate is arranged such that the protrusions of said light guide plate are at least partly positioned in said recesses.
  • a redirection sheet may be arranged at the front side of said light guide plate, where the redirection sheet has a prism- faced surface facing the front side of the light guide plate.
  • Such a redirection sheet may be arranged in order to redirect the light exiting the light guide plate into a desired direction.
  • the prism- faced surface of the redirection sheet may comprise a second array of extended mutually parallel protrusions that preferably has a triangularly shaped cross-section.
  • the tilt angle of the protrusions of the second array may be constant or may vary along the second array.
  • Figure Ia illustrates, in cross-sectional view, an embodiment of a light- emitting device of the present invention.
  • Figure Ib illustrates, in perspective view, the embodiment of figure Ia.
  • Figure 2 illustrates another embodiment of a light-emitting device of the present invention.
  • Figure 3 illustrates yet another embodiment of a light emitting device of the present invention.
  • a light emitting device 100 of one embodiment of the present invention is illustrated in figure Ia, and comprises an array of a plurality of light emitting diodes (LEDs) 107, arranged mutually spaced apart on a substrate 108.
  • the light emitting diodes 107 are arranged to emit light in essentially the same general direction L, essentially along the surface of the substrate 108, and in the direction of the array of the LEDs.
  • LEDs capable of emitting light in a general direction essentially along the surface of the substrate that they are mounted on are especially suitable for use in the present invention. Examples of such diodes are those commonly known as side emitting diodes.
  • the term "light emitting diode”, herein abbreviated “LED” refers however to any type of light emitting diode known to those skilled in the art, and encompasses, but is not limited to, inorganic based LEDs, organic based LEDs (OLEDs and polyLEDs) and laser diodes.
  • the light-emitting device 100 further comprises a light guide plate 101 of a translucent material having a front surface 102 and an opposing back surface 103 facing the light emitting diodes 107.
  • the light guide plate is arranged to receive light from the light emitting diodes via the back surface 103, to distribute the received light and to transmit the distributed light to the surroundings via the front surface 102.
  • Suitable materials for use in the light guide plate 101 include translucent materials such as, but not limited to, polymeric materials, i.e. PMMA or polycarbonate, ceramic materials and glass materials.
  • the back surface 103 of the light guide plate 101 presents a first array of protrusions 104 extending towards the substrate 108. Between each two adjacent protrusions 104 is formed a space, and the light guide plate 101 is arranged such that the array of protrusions 104 is aligned to the array of light emitting diodes 107 on the substrate such that the LEDs 107 are located in the so formed spaces between adjacent protrusions 104.
  • the protrusions 104 are designed to have a light receiving face 105, through which face light from the light emitting diodes 107 is transmitted into the light guide plate 101.
  • the protrusions 104 also has a light reflection face 106, typically the alternate face of the protrusion, on which face light, that has been transmitted into the light guide 101, is reflected towards the front surface of the light guide plate.
  • the protrusions have a triangularly shaped cross-section, preferably as illustrated in figure Ia, being asymmetric such that the receiving face 105 has a steeper slope than the reflection face 106.
  • the angle CC between the receiving face 105 and the front surface 102 of the light guide plate 101 is larger than the angle ⁇ between the reflection face 106 and the front surface 102.
  • the angle CC is typically in the range of from 60 to 90°, and the angle ⁇ is typically in the range of from 1 to 15°.
  • the pitch of the protrusions 104 of the light guide plate 101 i.e. the repetitive distance between adjacent protrusions, is typically in the range of from 1 to 30 mm, for example about 10 to 20 mm.
  • light from the light emitting diodes 107 is transmitted into the light guide plate via the receiving faces 105 of the protrusions 104.
  • the light When traveling in the light guide plate, the light will alternately encounter the front surface 102 of the light guide plate or a reflection face 106 of a protrusion.
  • the light is transmitted out of the light guide plate 101, or is reflected back (total internal reflection) into the light guide plate, towards the back surface 103 where it will encounter a reflection face 106 for reflection again towards the front surface 102. Due to the angle between the front surface 102 and the reflection face 106, the incidence angle at this following encounter with the front surface 102 will be lower than the incidence angel at the preceding encounter, until the incidence angle eventually becomes lower than the critical angle for transmission out of the light guide.
  • light will also be able to exit the light guide through the back surface 103 of the light guide plate, when the angle of incidence on the reflection faces 106 so allows.
  • the substrate 108, on which the light emitting diodes 107 are arranged with a reflective coating or the like in order to reflect this light back towards and into the light guide plate 101.
  • the reflection faces 106 may be provided with a reflective coating 109. Light transmitted out of the light guide plate via the reflection faces 106 will be reflected back towards the front surface of the light guide plate. This will enhance the light utilization efficiency of the device.
  • Such a reflective layer 109 may also prevent stray light from the light emitting diodes 107 to enter the light guide plate via the reflection faces 106 of the protrusions 104.
  • the array of mutually spaced apart LEDs 107 may be an array of mutually spaced apart rows, where each row comprises multiple LEDs.
  • the array of protrusions 104 may be an array of extended, mutually parallel protrusions, where a whole row, i.e. more than one light emitting diode, is located in a single space between two adjacent protrusions. Thus, more than one light emitting diode 107 provides light to the receiving face 105.
  • the multiple LEDs 107 forming a row and providing light to a single receiving face 105 may act as a spatially extended, linear, light source. If one of these light emitting diodes in such a row incidentally break down, the impact on the overall performance of the light emitting device is only minor, since the neighboring light emitting diodes providing light to the same receiving face as the broken light emitting diode still are functioning.
  • light-emitting diodes of more than one color may be used to provide light to the same receiving face, in order to provide a color variable light-emitting device.
  • three or more independently addressable light emitting diodes of different colors for example a red, a green and a blue LED, may form a color variable lighting unit (an RGB- unit).
  • the substrate 108 on which the LEDs are arranged comprises a plurality of recesses 209 between mutually spaced apart light emitting diodes 107.
  • the plurality of recesses 209 is preferably arranged in such a way that the protrusions 104 of the wave guide plate 101 extends at least partly into the recesses 209 of the substrate 108. Hence, the distance between two adjacent such recesses 209 corresponds to the distance between two adjacent protrusions 104 of the light guide plate 101. This improves and facilitates the alignment of the LEDs 107 with the receiving faces 105 of the protrusions 104 of the light guide plate. As will be apparent to those skilled in the art, the light from a light-emitting device as illustrated in figures 1 and 2 will typically exit the light guide plate via the front surface 102 thereof into the surroundings at an noticeable angle with respect to the normal of the front surface 102.
  • such a light-emitting device may be well suited for illuminating the ceiling when hung on a wall, or for illuminating a wall when arranged in the ceiling, but also for other purposes where light emission out of the normal of the front surface is desired.
  • it is desired to redirect the light exiting the light guide plate for example to obtain light having a main direction at or close to the normal of the front surface of the light guide plate.
  • a redirection sheet 310 may be arranged at the front surface 102 to receive light that exits the light guide plate 101 via the front surface 102, in order to redirect the main direction of this light.
  • An example of such a redirection sheet 310 comprises a sheet of a translucent material (i.e. plastic, ceramic or glass), which has a prismatic surface 311 facing the front surface 102 of the light guide plate.
  • a translucent material i.e. plastic, ceramic or glass
  • the prismatic surface 311 comprises a second array of mutually parallel protrusions 312.
  • the protrusions 312 of the second array are advantageously essentially parallel to the protrusions 104 of the light guide plate 101.
  • the protrusions 312 of the second array have a triangularly shaped cross-section with an apex angle in the range of from 20 to 70°.
  • the protrusions 312 of the second array are typically formed at a pitch (distance between two adjacent protrusions) that are markedly lower than the pitch of the protrusions 104 of the first array.
  • the pitch of the protrusions 312 of the second array is in the range of about 50 to 300 ⁇ m.
  • the protrusions 312 of the second array may be symmetric or asymmetric with respect to the normal of the front surface 102 of the light guide plate, in the sense that the center line of the protrusions may be parallel (symmetric) or non-parallel (asymmetric) to the normal of the front surface 102.
  • the centerline of a protrusion having a triangularly shaped cross-section is a thought line that divides the apex angle into to two equally large portions.
  • ⁇ 0° refers to a symmetric protrusion
  • ⁇ > 0° refers to an asymmetric protrusion tilted along the general direction of light emitted by the light emitting diodes
  • ⁇ ⁇ 0° refers to an asymmetric protrusion tilted against the general direction of light emitted by the light emitting diodes.
  • ⁇ > 0° refers to a protrusion tilted to the right
  • ⁇ ⁇ 0° refers to a protrusion tilted to the left as shown in Figure 3).
  • the tilt angle ⁇ of the protrusions 312 of the second array is typically in the range of from -15° to 15°, and may be constant or may vary along the array.
  • the apex and tilt angle of the protrusions 312 of the second array have been shown to affect the light exiting the redirection sheet into the surrounding.
  • One effect of a redirection sheet 310 is that the exiting light is given a tendency to show a plurality of intensity peaks at different angles relative to the normal of the redirection sheet.
  • apex angle value of about 40° At an apex angle value of about 40°, only one intensity peak appeared. Thus, in some embodiments of the present invention, about 40° represent a preferred apex angle, since a single intensity peak is achieved.
  • tilt angle ⁇ of about 11° the light exits the redirection sheet 310 approximately parallel to the normal of the redirection sheet.
  • a tilt angle ⁇ of about 11° is preferred since such a light-emitting device produces light perpendicular to the surface of the light-emitting device.
  • a lower tilt angle for example 0°
  • light exits the redirection sheet 310 at a negative angle to the normal of the redirection sheet.
  • a higher tilt such as 15°
  • the tilt angle ⁇ of the protrusions 312 of the second array varies along the extension of the second array in order to direct light from different portions of the device into different directions.
  • the tilt angle ⁇ may decrease, for example from about 15° to -5°, such as from 11° to 0°, along the second array in the general direction of light emitted by the LEDs (i.e. if the LEDs are arranged to emit light generally to the right, the tilt angle ⁇ of the protrusions 312 of the second array is higher in a left portion of the second array then in a right portion of the array).
  • This manner of varying the tilt angle will lead to a focusing of the light from the light-emitting device of the present invention.
  • the redirection sheet 310 may be divided into two or more domains, where the tilt angle ⁇ of the protrusions 312 of the redirection sheet has a first value in a first such domain, and a second such value in a second domain. This may be used in order to achieve a light distribution with for example two intensity peaks at two different angles.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)

Abstract

Cette invention concerne un dispositif électroluminescent (100) comprenant plusieurs diodes électroluminescentes (107) disposées à distance les unes des autres sur un substrat (108). Le dispositif comprend également une plaque guide de lumière (101) qui présente une surface avant (102) et une surface arrière opposée (103) sur laquelle figure un réseau de protubérances (104) s'étendant vers le substrat. La plaque guide de lumière est conçue de telle sorte que les diodes électroluminescentes sont placées dans des espaces formés entre des protubérances adjacentes. La lumière provenant des multiples diodes électroluminescentes peut être transmise dans la plaque guide de lumière et elle peut être diffusée dans la plaque guide de lumière avant d'en ressortir à travers sa face avant. Un tel mode de réalisation permet d'obtenir un dispositif électroluminescent fournissant une lumière bien diffusée depuis plusieurs sources lumineuses ponctuelles.
PCT/IB2007/053675 2006-09-15 2007-09-12 Luminaire à diodes électroluminescentes fin et plat WO2008032275A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06120715.5 2006-09-15
EP06120715 2006-09-15

Publications (1)

Publication Number Publication Date
WO2008032275A1 true WO2008032275A1 (fr) 2008-03-20

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2007/053675 WO2008032275A1 (fr) 2006-09-15 2007-09-12 Luminaire à diodes électroluminescentes fin et plat

Country Status (1)

Country Link
WO (1) WO2008032275A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2463989A (en) * 2008-10-01 2010-04-07 Optovate Ltd LED array fabrication
EP2280217A1 (fr) * 2009-07-28 2011-02-02 LG Innotek Co., Ltd. Unité d'éclairage avec une plaque de guide de lumière et appareil d'affichage doté de celle-ci
EP2300871A2 (fr) * 2008-06-13 2011-03-30 3M Innovative Properties Company Générateur de lumière à concentration
US20110090423A1 (en) * 2008-06-13 2011-04-21 Wheatley John A Illumination device with progressive injection
WO2014193830A1 (fr) * 2013-05-31 2014-12-04 3M Innovative Properties Company Luminaire pour passage piéton
EP4008950A4 (fr) * 2019-08-01 2023-07-05 LG Innotek Co., Ltd. Dispositif d'éclairage

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11329030A (ja) * 1998-05-21 1999-11-30 Mitsubishi Rayon Co Ltd プリズムシートおよび面光源素子
DE19860696A1 (de) * 1998-12-29 2000-07-06 Siemens Ag Lichtquellenelement mit seitlicher schräger Lichteinkopplung
US6241358B1 (en) * 1998-03-31 2001-06-05 Nitto Jushi Kogyo Kabushiki Kaisha Tandem lighting panel
US20010017774A1 (en) * 2000-02-24 2001-08-30 Tomotaka Ito Surface light source system
EP1326102A1 (fr) * 2000-07-24 2003-07-09 Mitsubishi Rayon Co., Ltd. Dispositif d'eclairage de surface comprenant une feuille a prisme
DE102004046256A1 (de) * 2004-09-23 2006-04-06 Osram Opto Semiconductors Gmbh Oberflächenleuchtsystem

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6241358B1 (en) * 1998-03-31 2001-06-05 Nitto Jushi Kogyo Kabushiki Kaisha Tandem lighting panel
JPH11329030A (ja) * 1998-05-21 1999-11-30 Mitsubishi Rayon Co Ltd プリズムシートおよび面光源素子
DE19860696A1 (de) * 1998-12-29 2000-07-06 Siemens Ag Lichtquellenelement mit seitlicher schräger Lichteinkopplung
US20010017774A1 (en) * 2000-02-24 2001-08-30 Tomotaka Ito Surface light source system
EP1326102A1 (fr) * 2000-07-24 2003-07-09 Mitsubishi Rayon Co., Ltd. Dispositif d'eclairage de surface comprenant une feuille a prisme
DE102004046256A1 (de) * 2004-09-23 2006-04-06 Osram Opto Semiconductors Gmbh Oberflächenleuchtsystem

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2300871A2 (fr) * 2008-06-13 2011-03-30 3M Innovative Properties Company Générateur de lumière à concentration
KR101571919B1 (ko) * 2008-06-13 2015-11-25 쓰리엠 이노베이티브 프로퍼티즈 컴파니 시준 광 엔진
US8608362B2 (en) 2008-06-13 2013-12-17 3M Innovative Properties Company Collimating light engine
EP2300871A4 (fr) * 2008-06-13 2012-03-07 3M Innovative Properties Co Générateur de lumière à concentration
US20110090423A1 (en) * 2008-06-13 2011-04-21 Wheatley John A Illumination device with progressive injection
GB2463989B (en) * 2008-10-01 2010-10-27 Optovate Ltd Illumination apparatus
GB2463989A (en) * 2008-10-01 2010-04-07 Optovate Ltd LED array fabrication
GB2463954A (en) * 2008-10-01 2010-04-07 Optovate Ltd LED array fabrication
US8985810B2 (en) 2008-10-01 2015-03-24 Optovate Limited Illumination apparatus
GB2464102A (en) * 2008-10-01 2010-04-07 Optovate Ltd Illumination apparatus comprising multiple monolithic subarrays
EP2280217A1 (fr) * 2009-07-28 2011-02-02 LG Innotek Co., Ltd. Unité d'éclairage avec une plaque de guide de lumière et appareil d'affichage doté de celle-ci
US8662729B2 (en) 2009-07-28 2014-03-04 Lg Innotek Co., Ltd. Light unit and display apparatus having the same
WO2014193830A1 (fr) * 2013-05-31 2014-12-04 3M Innovative Properties Company Luminaire pour passage piéton
EP4008950A4 (fr) * 2019-08-01 2023-07-05 LG Innotek Co., Ltd. Dispositif d'éclairage
US11828433B2 (en) 2019-08-01 2023-11-28 Lg Innotek Co., Ltd. Lighting device

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