WO2009087583A1 - Light output device with switchable reflector - Google Patents

Light output device with switchable reflector Download PDF

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Publication number
WO2009087583A1
WO2009087583A1 PCT/IB2009/050006 IB2009050006W WO2009087583A1 WO 2009087583 A1 WO2009087583 A1 WO 2009087583A1 IB 2009050006 W IB2009050006 W IB 2009050006W WO 2009087583 A1 WO2009087583 A1 WO 2009087583A1
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WO
WIPO (PCT)
Prior art keywords
device
light source
light
switchable
reflector
Prior art date
Application number
PCT/IB2009/050006
Other languages
French (fr)
Inventor
Rifat A. M. Hikmet
Ties Van Bommel
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
Priority to EP08100186.9 priority Critical
Priority to EP08100186 priority
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2009087583A1 publication Critical patent/WO2009087583A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21VFUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V14/00Controlling the distribution of the light emitted by adjustment of elements
    • F21V14/003Controlling the distribution of the light emitted by adjustment of elements by interposition of elements with electrically controlled variable light transmissivity, e.g. liquid crystal elements or electrochromic devices
    • AHUMAN NECESSITIES
    • A47FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47FSPECIAL FURNITURE, FITTINGS, OR ACCESSORIES FOR SHOPS, STOREHOUSES, BARS, RESTAURANTS OR THE LIKE; PAYING COUNTERS
    • A47F3/00Show cases or show cabinets
    • A47F3/001Devices for lighting, humidifying, heating, ventilation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10009Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin characterized by the number, the constitution or treatment of glass sheets
    • B32B17/10036Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin characterized by the number, the constitution or treatment of glass sheets comprising two outer glass sheet
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10165Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin particular functional features of the laminated glazing
    • B32B17/10174Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/1055Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin characterized by the resin layer, i.e. interlayer
    • B32B17/10706Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin characterized by the resin layer, i.e. interlayer being photo-polymerized
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/1055Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin characterized by the resin layer, i.e. interlayer
    • B32B17/10761Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin characterized by the resin layer, i.e. interlayer containing vinyl acetal
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21SNON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S10/00Lighting devices or systems producing a varying lighting effect
    • F21S10/02Lighting devices or systems producing a varying lighting effect changing colors
    • F21S10/023Lighting devices or systems producing a varying lighting effect changing colors by selectively switching fixed light sources
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21VFUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V33/00Structural combinations of lighting devices with other articles, not otherwise provided for
    • F21V33/006General building constructions or finishing work for buildings, e.g. roofs, gutters, stairs or floors; Garden equipment; Sunshades or parasols
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21WINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO USES OR APPLICATIONS OF LIGHTING DEVICES OR SYSTEMS
    • F21W2121/00Use or application of lighting devices or systems for decorative purposes, not provided for in codes F21W2102/00 – F21W2107/00
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21WINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO USES OR APPLICATIONS OF LIGHTING DEVICES OR SYSTEMS
    • F21W2131/00Use or application of lighting devices or systems not provided for in codes F21W2102/00-F21W2121/00
    • F21W2131/10Outdoor lighting
    • F21W2131/107Outdoor lighting of the exterior of buildings
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21WINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO USES OR APPLICATIONS OF LIGHTING DEVICES OR SYSTEMS
    • F21W2131/00Use or application of lighting devices or systems not provided for in codes F21W2102/00-F21W2121/00
    • F21W2131/40Lighting for industrial, commercial, recreational or military use
    • F21W2131/405Lighting for industrial, commercial, recreational or military use for shop-windows or displays
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21YINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2105/00Planar light sources
    • F21Y2105/10Planar light sources comprising a two-dimensional array of point-like light-generating elements
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21YINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2113/00Combination of light sources
    • F21Y2113/10Combination of light sources of different colours
    • F21Y2113/13Combination of light sources of different colours comprising an assembly of point-like light sources
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21YINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00Light-generating elements of semiconductor light sources
    • F21Y2115/10Light-emitting diodes [LED]
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/13718Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a change of the texture state of a cholesteric liquid crystal
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/165Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
    • G02F1/166Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect
    • G02F1/167Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect by electrophoresis
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58Optical field-shaping elements
    • H01L33/60Reflective elements

Abstract

Alight output device comprises at least one light source (4) having a light output which is generally directed in a first direction and a switchable reflector (6), which switchable between a transmissive mode for providing light in the first direction, and a reflecting mode for providing light in an opposite direction.

Description

LIGHT OUTPUT DEVICE WITH SWITCHABLE REFLECTOR

FIELD OF THE INVENTION

This invention relates to light output devices, particularly but not exclusively using discrete light sources associated with a transparent substrate structure.

BACKGROUND OF THE INVENTION

One known example of this type of light output device is a so-called "LED in glass" device. An example is shown in Figure 1. Typically a glass plate is used, with a transparent conductive coating (for example ITO) forming electrodes. The conductive coating is patterned in order to make the electrodes that are connected to a semiconductor LED device. The assembly is completed by laminating the glass, with the LEDs inside a thermoplastic layer (for example polyvinyl butyral, PVB).

Applications of this type of device are shelves, showcases, facades, office partitions, wall cladding, and decorative lighting. The light output device can be used for illumination of other objects, for display of an image, or simply for decorative purposes. In current products, light is typically emitted from one surface. There are applications in which it is desirable to be able to choose from which surface light is emitted, and provide control for this function.

SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a light output device comprising: at least one light source having a light output which is generally directed in a first direction; and a switchable reflector, which is switchable between a transmissive mode for providing light in the first direction, and a reflecting mode for providing light in an opposite direction.

This arrangement enables the light output characteristics of the device to be controlled, so that opposite surfaces can be used for illumination in different modes of operation of the device. The light source is preferably sandwiched between first and second substrates, and the first direction is from the light source towards the first substrate, and the opposite direction is from the light source towards the second substrate. The switchable reflector can then be provided between the light source device and the first substrate. This provides a compact integrated structure.

The device may comprise an electrode arrangement provided between the first and second substrates and comprising at least semi-transparent electrodes, wherein the at least one light source is electrically driven by the electrodes.

In a preferred embodiment, the light sources comprise an array of light sources. The light sources of the array can for example be different colours, and the switchable reflectors can then be used to control the overall light output colour.

Each light source can comprise one or more LED devices.

The switchable reflector is preferably also arranged as an array of reflector portions, with each reflector portion associated with a respective light source device or group of light source devices. The reflector portions of the array can then be independently switchable. The reflection from the reflector can be made wavelength dependent.

The invention also provides a method of providing a light output comprising: generating a light source output from at least one light source generally directed in a first direction; and - in a first mode of operation, switching a switchable reflector to a transmissive mode for providing light in the first direction, and in a second mode of operation switching the switchable reflector to a reflecting mode for providing light in an opposite direction.

It is noted that the invention relates to all possible combinations of features recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 schematically shows a known LED in glass illumination device;

Figure 2 schematically shows an example of the structure of the device of Figure 1;

Figures 3A and 3B schematically show the concept underlying the invention; Figure 4 schematically shows an example of the light output device of the invention; and

Figure 5 schematically shows another example of the light output device of the invention. The same reference numerals are used to denote similar parts throughout the

Figures.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 2 shows a known LED in glass structure. The light output device comprises glass plates 1 and 2. Between the glass plates are (semi-) transparent electrodes 3 a and 3b (for example formed using ITO or thin conductive wires), and an LED 4 connected to the transparent electrodes 3 a and 3b. A layer of thermoplastic material 5 is provided between glass plates 1 and 2 (for example PVB or UV resin).

When transparent electrodes are used, they are not visible to the viewer, and they do not introduce non-uniformities to the light output.

The electrodes are preferably substantially transparent, by which is meant that they are imperceptible to a viewer in normal use of the device. If the conductor arrangement does not introduce a noticeable variation in light transmission (for example because it is not patterned, or because the pattern cannot be seen), a transparency of greater than or equal to 50% may be sufficient for the system to appear transparent. More preferably, the transparency is greater than 70%, more preferably 90%, and even more preferably 99%. If the conductor arrangement is patterned (for example because thin wires are used), the transparency is preferably greater than 80%, more preferably 90%, but most preferably greater than 99%. The electrodes can be made of a transparent material such as ITO or they can be made of an opaque material such as copper but be sufficiently thin so that they are not visible in normal use. Examples of suitable materials are disclosed in US-A-5 218 351.

A particularly useful opaque conductive material may be a conductive ink deposited using silkscreen or inkjet printing, because this allows the conductor arrangement to be deposited in a cost-effective manner.

The glass plates typically may have a thickness of 1. lmm - 2.1 mm. The spacing between electrode is typically 0.01 - 3 mm, for example around 0.15 mm. The thermoplastic layer has a thickness of 0.5mm- 2mm, and the electrical resistance of the electrodes is in the range 1 - 80 Ohm, or 1-50 Ohm or more preferably 2-20 Ohm, or 10-30 Ohms/square.

The invention provides a light output device in which a switchable reflector is switchable between a transmissive mode for providing light in the first direction, and a reflecting mode for providing light in an opposite direction. This enables the output from opposite sides of the device to be controlled.

Figure 3 shows the basic principle underlying the invention, and shows a light source in the form of an LED 4 adjacent a switchable reflector 6. The reflector 6 is provided in the light output path, namely on the emission side of the LED 4. Figure 3 A shows a transparent state in which light is emitted mainly from the upper surface. In a reflective state of Figure 3B, light emitted by the LED is reflected towards the lower surface. The switchable reflector is between the light source device 4 and the first substrate 1 and is thus integrated into the structure of the device.

Although not shown in Figure 3, the device has the electrode arrangement between the first and second substrates, as shown in Figure 2.

In preferred embodiments, the device comprises an array of light sources, and the reflector is also arranged as an array of reflectors portions, as shown in Figure 4.

Figure 4 shows four reflector portions 6a - 6d. The reflector portions are independently addressable, so that the intensity of illumination from both sides (relative to each other) can be controlled. In Figure 4, one reflector portion 6c is in the reflective mode, and the others 6a, 6b, 6d are in transmissive mode.

In addition to controlling the light output direction, the reflectors can be used to control the appearance of the device when the light sources are turned off. In particular, from the second side (i.e. the side to which reflected light is directed - the lower side in the Figures), a transparent or substantially reflecting surface be visible.

The levels of transmission and reflection can be varied based on the number of reflector portions in each mode and/or by adjusting the reflection characteristics of the reflector by the applied electric field. One application is for secrecy windows, which are switchable between a secrecy (reflecting) mode and a non-secrecy (transmissive) mode. The LEDs can also be of different colours. In this way, the colour and colour temperature of light output from the two sides can be controlled.

In another modification shown in Figure 5, the reflection from the reflector portions is wavelength dependent. Thus, a first portion 50 of the light spectrum is transmitted and a second portion 52 is reflected, giving different colours. In the transmissive mode, a white light output can be provided, and in the reflecting mode, blue light can be transmitted and red light reflected (for example).

The switchable reflector can comprise a cholesteric filter, which can be gradually switched electrically between the transparent state and reflective state, with gradual change in reflectivity based on the drive voltage.

In US patents US 5762823 and US 5798057 such reflectors are described. They are based on cholesteric liquid crystal (LC) materials which can reflect a band of circularly polarized light. Upon application of an electric field, they can be made to be transparent. Examples described in the US patents above make use of a polymer network which enables reversible switching. There are also other modes of cholesteric LC material switching such as bi-stable switching which can also be used in the present application.

Apart from cholesteric materials, it is also possible to use other effects which can show switchable reflection. So-called electrically polymer dispersed LC and LC gels can also give rise to electrically induced scattering. Such materials can switch between scattering and transparent states. These materials can be formulated so that they show excess diffuse reflection. They can therefore also be used as a switchable diffuse reflector in the present application.

The other type of materials which can be used as switchable reflectors are based on in-plane electrophoreses. In such a cell, electrophoretic particles which reflect light are used. Such particles can be moved in and out of the path of the light and thus the cell can be switched between transmitting and reflective states.

It is also possible to make use of the so called roll-blind technology. This is based on a thin film with a conductive layer. In a neutral state, the film is in a rolled state. Upon application of a voltage between a conductive surface and the rolled film which is attached to the surface, from one end the film can be switched between the rolled and unrolled states.

In the examples above, a single LED is shown. However, the LEDs may be in groups of LEDs.

The invention is of particular interest for signage, decorative lighting such as lamps, windows, architectural glass, and secrecy windows, although other applications are possible, such as furniture and other decorative items.

Various other possibilities are within the scope of the various aspects of the invention, as defined by the attached claims.

Various other modifications will be apparent to those skilled in the art.

Claims

CLAIMS:
1. A light output device comprising: at least one light source (4) having a light output which is generally directed in a first direction; and a switchable reflector (6), which is switchable between a transmissive mode for providing light in the first direction, and a reflecting mode for providing light in an opposite direction.
2. A device as claimed in claim 1, wherein the light source (4) is sandwiched between first and second substrates (1,2), and wherein the first direction is from the light source (4) towards the first substrate (1), and the opposite direction is from the light source towards the second substrate.
3. A device as claimed in claim 2, wherein the switchable reflector (6) is between the light source (4) and the first substrate (1).
4. A device as claimed in any preceding claim, comprising: an electrode arrangement (3a,3b) provided between the first and second substrates (1,2) and comprising at least semi-transparent electrodes, wherein the at least one light source (4) is electrically driven by the electrodes.
5. A device as claimed in any preceding claim, comprising an array of light sources (4).
6. A device as claimed in claim 5, wherein the array comprises light sources of different colours.
7. A device as claimed in any preceding claim, wherein the light source (4) comprises an LED device.
8. A device as claimed in any preceding claim, wherein the light source (4) comprises a group of LED devices.
9. A device as claimed in any preceding claim, comprising an array of switchable reflector portions (6a,6b,6c,6d), each associated with a respective light source device (4) or group of light source devices.
10. A device as claimed in claim 9, wherein the reflector portions (6a,6b,6c,6d) of the array are independently switchable.
11. A device as claimed in any preceding claim, wherein the reflection from the reflector (6) is wavelength dependent.
12. A device as claimed in any preceding claim, wherein the switchable reflector (6) comprises a cholesteric filter, switchable scattering LC device, electrophoretic device or a roll-blind device.
13. A method of providing a light output comprising: generating a light source output from at least one light source (4) generally directed in a first direction; and in a first mode of operation, switching a switchable reflector (6) to a transmissive mode for providing light in the first direction, and in a second mode of operation, switching the switchable reflector (6) to a reflecting mode for providing light in an opposite direction.
PCT/IB2009/050006 2008-01-08 2009-01-05 Light output device with switchable reflector WO2009087583A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP08100186.9 2008-01-08
EP08100186 2008-01-08

Publications (1)

Publication Number Publication Date
WO2009087583A1 true WO2009087583A1 (en) 2009-07-16

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011033431A1 (en) * 2009-09-17 2011-03-24 Koninklijke Philips Electronics N.V. Lighting device with off-state white appearance
EP2384621A1 (en) * 2010-05-07 2011-11-09 WACHTER Christoph Lighting device, in particular for aquariums and terrariums and method for operating such a device
DE102011017098A1 (en) * 2011-04-14 2012-10-18 Osram Opto Semiconductors Gmbh Light-emitting device
WO2013132394A1 (en) * 2012-03-09 2013-09-12 Koninklijke Philips N.V. Color adjustable light emitting arrangement
CN103325776A (en) * 2012-03-22 2013-09-25 光芯科技股份有限公司 Light emitting means
CN103542278A (en) * 2012-07-10 2014-01-29 元太科技工业股份有限公司 Lamp
WO2014020249A1 (en) * 2012-08-01 2014-02-06 Peugeot Citroen Automobiles Sa Glazing unit able to produce a light beam in a given direction by means of integrated leds
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US9976847B2 (en) 2014-04-16 2018-05-22 Samsung Electronics Co., Ltd. Polarization independent optical shutter using cholesteric liquid crystals and three-dimensional image acquisition apparatus employing the same

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