WO2006117733A2 - Lampe a decharge, en particulier lampe fluorescente, systeme d'eclairage et affichage - Google Patents

Lampe a decharge, en particulier lampe fluorescente, systeme d'eclairage et affichage Download PDF

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Publication number
WO2006117733A2
WO2006117733A2 PCT/IB2006/051327 IB2006051327W WO2006117733A2 WO 2006117733 A2 WO2006117733 A2 WO 2006117733A2 IB 2006051327 W IB2006051327 W IB 2006051327W WO 2006117733 A2 WO2006117733 A2 WO 2006117733A2
Authority
WO
WIPO (PCT)
Prior art keywords
heat
discharge lamp
reflective layer
light
discharge
Prior art date
Application number
PCT/IB2006/051327
Other languages
English (en)
Other versions
WO2006117733A3 (fr
Inventor
Rene J. Hendriks
Christianus J. Roozekrans
Jorgen Meeusen
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 WO2006117733A2 publication Critical patent/WO2006117733A2/fr
Publication of WO2006117733A3 publication Critical patent/WO2006117733A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H01J61/35—Vessels; Containers provided with coatings on the walls thereof; Selection of materials for the coatings

Definitions

  • Discharge lamp in particular a fluorescent lamp, illumination system, and display
  • the invention relates to a discharge lamp, in particular a fluorescent lamp, comprising: an at least partially light-transmissive discharge vessel filled with an ionizable substance, multiple electrodes connected to said vessel, between which electrodes a discharge extends during lamp operation.
  • a discharge lamp in particular a fluorescent lamp
  • the invention also relates to an illumination system for illumination display devices, comprising at least one of such discharge lamp.
  • the invention further relates to a display device comprising such an illumination system.
  • Fluorescent light sources are commonly known and are applied in, for example, illumination systems.
  • Such an illumination system is referred to as "direct-lit” backlight or “direct-under” type of backlight illumination system.
  • the illumination systems are used, inter alia, as back or side lighting of (image) display devices, for example, for television receivers and monitors.
  • Such illumination systems can particularly be used suitably as a backlight for non-emissive displays, such as liquid crystal display devices, also referred to as LCD panels, which are used in (portable) computers or (cordless) telephones.
  • the illumination system is particularly suitable for application in large-screen LCD display devices for television and professional applications.
  • Said display devices generally include a substrate provided with a regular pattern of pixels, each driven by at least one electrode.
  • the display device employs a control circuit.
  • the light originating from the backlight is modulated by means of a switch or a modulator, while applying various types of liquid crystal effects.
  • the display may be based on electrophoretic or electromechanical effects.
  • a tubular low-pressure mercury vapor discharge lamp for example, one or more cold-cathode fluorescent lamps, hot-cathode fluorescent lamps, or external electrode fluorescent lamps (EEFL) may usually be employed as discharge lamps in the illumination system.
  • a phosphorous coating is generally applied to enable low-pressure mercury vapor discharge lamps to convert UV light to other wavelengths, for example, to UV-B light and UV-A light for tanning purposes (sun panel lamps) or to visible radiation for general illumination purposes.
  • Such discharge lamps are therefore also referred to as fluorescent lamps.
  • conventional fluorescent lamps have several drawbacks.
  • a fluorescent lamp is also an infrared (IR) radiator causing a local temperature rise near the electrodes due to a so-called hot spot generated by both electrodes.
  • IR infrared
  • Optical (plastic) foils used in illumination systems generally used for polarizing or collimating visible light generated by the fluorescent lamps, have a limited temperature resistance and can barely survive heat radiated by the electrodes.
  • a display device such as an LCD, has a maximum operation temperature and is relatively sensitive to temperature gradients. Exposing both the optical foils and the display device to the heat generated by conventional discharge lamps is detrimental for both the optical foils and the display device and will generally reduce the life span of these components significantly.
  • the object of the invention can be achieved by providing a discharge lamp as described in the opening paragraph, which lamp is characterized in that said vessel is at least partially covered with at least one heat-reflective layer for reflecting heat generated by said discharge lamp.
  • thermal radiation in one or more directions can be limited selectively, as a result of which distribution of heat generated by the discharge lamp can be managed.
  • heat caused by infrared radiation can be prevented, or at least obstructed, from radiating towards components of e.g. an illumination system, which are relatively heat-sensitive.
  • an illumination system which are relatively heat-sensitive.
  • Heat reflected by the heat-reflective layer can be reflected towards an area which is less sensitive to infrared radiation.
  • the use of a heat-reflective layer has the further advantage that this layer can be applied in a relatively easy and quick manner, wherein the degree and direction of heat reflection can be predetermined in a relatively accurate manner.
  • the use of the heat-reflective layer provides an increased degree of freedom of design of an illumination system comprising multiple discharge lamps according to the invention, because the mutual distance of heat-sensitive components and the discharge lamps of the illumination system becomes (significantly) less critical, thus allowing a relatively compact design of the illumination system.
  • infrared (IR) radiation is considered as electromagnetic radiation with a wavelength longer than visible light, but shorter than microwave radiation, which has typical wavelengths of between 700 nm and 1 mm.
  • each electrode A substantial part of the heat generated by the discharge lamp is generated on or at least near each electrode, resulting in the formation of a hot spot near each electrode.
  • the heat-reflective layer is preferably applied near each electrode. More preferably, each electrode is surrounded at least partially by said heat-reflective layer to cause heat reflection in a selective direction.
  • said heat-reflective layer is preferably substantially light- transmissive.
  • the heat-reflective layer can be applied onto the vessel to act as a heat shield without creating undesired dark areas on or near the lamp and hence on a display device which may be positioned near a plurality of said discharge lamps.
  • Not every material is suitable as a heat-reflective layer, because a majority of the (known) heat-reflective material absorbs at least a part of the wavelengths of the visible spectrum, thereby resulting in a loss of light output.
  • the material of the heat-reflective layer is preferably selected from the group of: ITO (indium oxide doped with tin oxide), ATO (antimony-doped tin oxide), FTO (fluorine-doped tin oxide) or AZO (aluminum-doped zinc oxide).
  • ITO indium oxide doped with tin oxide
  • ATO antimony-doped tin oxide
  • FTO fluorine-doped tin oxide
  • AZO aluminum-doped zinc oxide
  • the reflective layer is preferably applied onto either an inner or an outer surface of the vessel. It will also be conceivable for a person skilled in the art to apply, for example, a first heat-reflective layer onto an inner surface of the vessel and a second heat- reflective layer onto an outer surface of the vessel.
  • a first heat-reflective layer onto an inner surface of the vessel and a second heat- reflective layer onto an outer surface of the vessel.
  • the vessel In the case of a HCFL, such as a T5 or T8, or a CCFL, such as a Tl or T2, the vessel generally has a substantially cylindrical shape.
  • the heat-reflective layer preferably covers a longitudinal portion of an inner and/or an outer surface of the vessel.
  • the heat-reflective layer may be a separate layer, which may be provided on one side with an adhesive for applying said heat-reflective layer onto the vessel.
  • the discharge lamp comprises multiple heat-reflective layers, wherein only the hot spots of the lamp are selectively shielded by one or more heat-reflective layers.
  • the vessel is partially covered with a light- reflective layer, said light-reflective layer being at least partially reflective to visible light.
  • a reflective layer or prismatic layer is advantageously applied to improve the light efficiency and luminance of said discharge lamp for backlighting applications, while the light generated within the light source can be concentrated and directed efficiently in a desired direction. In this manner, a relatively uniform light distribution can be generated and transmitted through a light emission window, resulting in a relatively uniform illumination of a display device.
  • Said light-reflective layer and the heat-reflective layer can be stacked together as a laminate, wherein said laminate is applied onto the vessel of the discharge lamp.
  • the heat-reflective layer and the light-reflective layer are mutually integrated so as to form a single multifunctional layer.
  • the invention also relates to an illumination system for illuminating display devices, the illumination system comprising: a light emission window for emitting light in the direction of a display device, a reflector for reflecting light, at least a part of which reflector is arranged substantially parallel to and opposite the light emission window, and at least one elongated discharge lamp according to the invention, said discharge lamps being arranged between said light emission window and said reflector, wherein the heat-reflective layer of the discharge lamp is positioned in such a way that heat generated by said discharge lamp is reflected in a direction substantially opposite said light emission window.
  • the light emission window generally comprises multiple optical foils which are relatively heat-sensitive.
  • each heat-reflective layer preferably covers at least a part of the discharge lamp facing the light emission window.
  • the relatively heat-resistant reflector will absorb the heat reflected by the heat-reflective layer, by means of which reflector the absorbed heat will subsequently be transferred substantially to the local atmosphere surrounding said reflector.
  • a part of each discharge lamp facing the reflector is left substantially uncovered by said heat-reflective layer. In this manner, thermal reflection towards the light emission window can be prevented.
  • the invention further relates to a display device comprising an illumination system according to the invention. Besides Liquid Crystal Displays (LCD), any type of display requiring active illumination by an external illumination system according to the invention can be used.
  • LCD Liquid Crystal Displays
  • Figure 1 is a cross-section of an illumination system according to the invention
  • Figure 2 is a side view of a fluorescent lamp according to the invention
  • Figure 3 is a side view of another fluorescent lamp according to the invention.
  • FIG. 1 is a cross-section of an illumination system 1 according to the invention.
  • the illumination system 1 comprises a light emission window 2, a reflective backing plate 3 positioned at a distance from and substantially parallel to the light emission window 2, and a plurality of fluorescent lamps 4a, 4b, 4c, 4d arranged between the light emission window 2 and the backing plate 3.
  • the illumination system 1 is adapted to illuminate a display device 5, such as an LCD.
  • the fluorescent lamps 4a, 4b, 4c, 4d shown are mutually different so as to show different embodiments of these lamps 4 according to the invention. However, in practice, a single embodiment of the fluorescent lamps 4a, 4b, 4c, 4d according to the invention will generally be used.
  • a first fluorescent lamp 4a (shown at the extreme left) comprises a cylindrical discharge envelope 6, an inner surface of which is provided with a phosphorous coating 7 for converting UV light into visible light.
  • An outer surface of the first fluorescent lamp 4a is provided with a heat-reflective layer 8 for reflecting heat, i.e. infrared radiation, generated within said envelope 6 towards the reflective backing plate 3, as a result of which a considerable, and hence detrimental, heat transfer towards the light emission window 2 and the display device 5 can be prevented. Overheating and a consequent reduction of the life expectancy of the light emission window 2 and the display device 5 can be counteracted in this way. More or less the same heat-reflective effect can be achieved in the second fluorescent lamp 4b.
  • both a portion of the inner surface and a portion of the outer surface of a cylindrical envelope 9 are provided with a heat-reflective layer 10, 11.
  • the heat-reflective layer 10 applied onto the inner surface of the envelope 9 is applied directly on this inner surface, while a phosphorous coating 12 is applied on the heat-reflective layer 10 and on a remaining part of the inner surface of the envelope 9.
  • the heat-reflective layer 11 applied onto the outer surface of the envelope 9 can be provided with light-reflective particles so as to reflect a considerable part of (visible) light towards the reflective backing plate 3 in order to achieve a more uniform illumination of the display device 5.
  • the third fluorescent lamp 4c is only provided with a single heat-reflective layer 13 applied onto an inner surface of an envelope 14, while a phosphorous coating 15 is applied in accordance with the embodiment shown in Figure 4b.
  • this heat-reflective layer 13 may also be provided with (visible) light-reflective particles.
  • the fourth fluorescent lamp 4d comprises a light-transmissive envelope 16, an inner surface of which is provided with a phosphorous coating 17 and an outer surface is provided with a laminate 18 of two layers 19, 20.
  • the laminate 18 comprises a heat-reflective layer 19, preferably made of ITO, and a light-reflective layer 20.
  • the light emission window 2, commonly known as diffuser plate, may also be provided with one or more heat-reflective layers (not shown) to counteract overheating of optical foils forming part of the light emission window 2.
  • FIG 2 is a side view of a fluorescent lamp 21 according to the invention.
  • the fluorescent lamp 21 comprises an elongated discharge vessel 22, a longitudinal portion of which is covered with a reflective layer 23.
  • Two extremities 23a of the reflective layer 23 are both heat-reflective and light-reflective, while a middle portion 23b of the reflective layer 23 is formed by a layer which is (only) light-reflective.
  • the heat-reflective portion is situated at both ends of the reflective layer 23, while both electrodes of the fluorescent lamp 21 and hot spots generated by these electrodes are situated in these end regions, as a result of which reflection of heat is most urgent in these regions.
  • Figure 3 is a side view of another fluorescent lamp 24 according to the invention.
  • the fluorescent lamp 24 shown in Figure 3 comprises a substantially cylindrical discharge vessel 25.
  • An outer surface of the discharge vessel 25 is provided with a multifunctional reflective layer 26 on a longitudinal portion of the discharge vessel 25.
  • the reflective layer 26 is multifunctional, because this layer 26 is able to reflect electromagnetic radiation of both the visible spectrum and the infrared spectrum, as a result of which a uniform illumination in an illumination system (see, for example, Figure 1) can be achieved, and overheating of heat-sensitive parts of the illumination system can be prevented or at least counteracted.

Landscapes

  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Planar Illumination Modules (AREA)

Abstract

Cette invention concerne une lampe à décharge, en particulier une lampe fluorescente, comprenant : une chambre de décharge au moins partiellement photoémettrice, remplie d'une substance ionisable; et de multiples électrodes qui sont connectées à cette chambre et entre lesquelles une décharge s'étend pendant le fonctionnement de la lampe. Cette invention concerne également un système d'éclairage pour dispositifs d'affichage par éclairage, comprenant plusieurs de ces lampes à décharge. Cette invention concerne en outre un dispositif d'affichage comprenant un tel système d'éclairage.
PCT/IB2006/051327 2005-05-04 2006-04-28 Lampe a decharge, en particulier lampe fluorescente, systeme d'eclairage et affichage WO2006117733A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP05103770 2005-05-04
EP05103770.3 2005-05-04

Publications (2)

Publication Number Publication Date
WO2006117733A2 true WO2006117733A2 (fr) 2006-11-09
WO2006117733A3 WO2006117733A3 (fr) 2009-03-19

Family

ID=37308377

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2006/051327 WO2006117733A2 (fr) 2005-05-04 2006-04-28 Lampe a decharge, en particulier lampe fluorescente, systeme d'eclairage et affichage

Country Status (1)

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WO (1) WO2006117733A2 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2152280A (en) * 1983-12-23 1985-07-31 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Lamp
US20020033668A1 (en) * 2000-08-08 2002-03-21 Yu Xihu Method for thoroughly eliminating electrophoresis effects of DC fluorescent lamp tube
WO2002103748A1 (fr) * 2001-06-19 2002-12-27 Koninklijke Philips Electronics N.V. Lampe a decharge de gaz a basse pression contenant une atmosphere gazeuse sans mercure
WO2004025692A1 (fr) * 2002-09-12 2004-03-25 Philips Intellectual Property & Standards Gmbh Lampe a decharge de gaz basse pression a substances emettrices d'electrons du type batio3

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2152280A (en) * 1983-12-23 1985-07-31 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Lamp
US20020033668A1 (en) * 2000-08-08 2002-03-21 Yu Xihu Method for thoroughly eliminating electrophoresis effects of DC fluorescent lamp tube
WO2002103748A1 (fr) * 2001-06-19 2002-12-27 Koninklijke Philips Electronics N.V. Lampe a decharge de gaz a basse pression contenant une atmosphere gazeuse sans mercure
WO2004025692A1 (fr) * 2002-09-12 2004-03-25 Philips Intellectual Property & Standards Gmbh Lampe a decharge de gaz basse pression a substances emettrices d'electrons du type batio3

Also Published As

Publication number Publication date
WO2006117733A3 (fr) 2009-03-19

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