WO2015132079A1 - Light guide for a point light source and associated lighting device - Google Patents

Light guide for a point light source and associated lighting device Download PDF

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Publication number
WO2015132079A1
WO2015132079A1 PCT/EP2015/053560 EP2015053560W WO2015132079A1 WO 2015132079 A1 WO2015132079 A1 WO 2015132079A1 EP 2015053560 W EP2015053560 W EP 2015053560W WO 2015132079 A1 WO2015132079 A1 WO 2015132079A1
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WO
WIPO (PCT)
Prior art keywords
light
light guide
cap
light source
curvature
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Application number
PCT/EP2015/053560
Other languages
French (fr)
Inventor
Olivier Rols
Pierre-Jean JOVENE
Original Assignee
Thales
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Publication of WO2015132079A1 publication Critical patent/WO2015132079A1/en

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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
    • G02B6/002—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 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
    • G02B6/0021—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 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces for housing at least a part of the light source, e.g. by forming holes or recesses
    • 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
    • G02B6/0075—Arrangements of multiple light guides
    • G02B6/0078—Side-by-side arrangements, e.g. for large area displays

Definitions

  • Light guide for point light source and associated lighting device
  • the field of the invention is that of light boxes for display device comprising a passive display operating by transmission. More specifically, the field of the invention is that of displays for display devices called "Head High” used in aeronautics and more recently in the automotive field.
  • a head-up display device is shown in FIG. It mainly comprises a transparent liquid crystal matrix display 1, a light box 2 illuminating this display, a collimation optics 3 and an optical mixer 4.
  • the mirror 5 is a simple reflecting mirror.
  • the collimating optics 3 gives the image displayed an image at a great distance in front of the eye Y of a user. It is schematically represented by a simple lens in FIG.
  • the optical mixer 4 ensures the superposition of the image displayed on the outside. It is represented by a thin blade in FIG.
  • the exterior landscape is symbolically represented by white chevrons. It can possibly be integrated in the windshield of the vehicle.
  • the displayed image must be visible day and night. Therefore, the light box must be particularly bright to ensure a good brightness of the image under high sun.
  • the light box generally comprises light sources arranged in a diffusing chamber and closed by a diffusing surface. This diffusing surface makes it possible both to uniformly distribute the light on the surface of the display and to ensure correct illumination of the pupil of the display device.
  • the light sources used may be fluorescent tubes or "CCFL", acronym for "Cold Cathod Fluorescent Light". More recently, these sources are light emitting diodes with high brightness. These diodes have the advantage of having excellent performance, high dynamics, high reliability and ensure perfect colorimetry. However, diodes are, by nature, point sources.
  • the object of the invention is to reduce these losses of light significantly.
  • the light box is segmented into a plurality of zones. Each zone is then illuminated by a collimated light source dedicated to said zone.
  • the subject of the invention is a light guide for a point or quasi-point light source comprising a substantially spherical transparent cap, said guide being made of a material transparent to the emission wavelength of said source of light. light, characterized in that the outer surface of said light guide comprises four parts:
  • a second portion operating in reflection, in the form of an elliptical paraboloid, having a first low rim and a first rim of greater circumference, attached to its lower rim at the first portion;
  • a fourth part operating in transmission corresponding to the exit face of the light guide and defined by the second high circumference of the third part.
  • one of the two focal points of the elliptical dish is coincident with at least one of the two centers of the toric cap.
  • one of the two foci of the elliptical dish is at a predetermined distance from at least one of the two centers of the toric cap, so as to adapt the angular aperture of the light beam from the light source and transmitted by the fourth part.
  • the first radius of curvature of the concave toric cap is substantially equal to the radius of curvature of the cap of the light source and the second radius of curvature of the concave toric cap is substantially equal to infinity.
  • the third part is rectangular or square or hexagonal.
  • the fourth part is a flat surface perpendicular or inclined with respect to the generatrix of the prism.
  • the invention also relates to a light box comprising a plurality of point or quasi-point light sources, characterized in that each light source comprises a light guide as defined above, the different light guides being joined.
  • a display device comprising at least one matrix display operating by transmission and a light box as defined above.
  • the device comprises a collimation optics and an optical mixer for superimposing the image of the matrix display on an outside landscape.
  • Figure 1 already commented represents a head-up display device
  • Figure 2 shows a sectional view of a light guide according to the invention
  • FIG. 3 represents a display device comprising a set of light guides according to the invention.
  • Figure 2 shows a sectional view of a light guide 20 according to the invention. It is intended to operate with a point or quasi-point light source 10 comprising a substantially spherical transparent cap 11.
  • This source is generally a light emitting diode or a laser diode. The light rays are shown in dashed lines in this FIG.
  • the light guide 20 is made of a material transparent to the emission wavelength of said light source. This material is usually an organic glass. Its general form is that of a faceted prism.
  • the generator or axis x-x of the prism is an axis centered on the prism and parallel to the different facets of the prism. Generally, the length of the prism does not exceed 10 centimeters and its width 1 to 2 centimeters.
  • the outer surface of the light guide has four parts detailed below.
  • a first part 21 operates in transmission. It corresponds to the entrance face of the light guide. It is shaped like a concave toric cap.
  • a torus has two radii of curvature. Generally, one of the two radii of curvature of the torus is substantially equal to the radius of curvature of the cap 1 1 of the light source. The value of the second radius of the torus is between the radius of curvature of the cap 1 1 and infinity. In the case of Figure 2, this toric cap is hemispherical.
  • This first part is located closer to the cap 1 1 of the light source. The optical function of this first part is to ensure that the light rays coming from the light source penetrate the light guide with the minimum of losses.
  • a second portion 22 operates in reflection. It is shaped like an elliptical paraboloid of revolution. It has a first low circumference and a first high circumference of greater circumference. It is attached on its lower edge to the first part, the distances between the focal points of the dish and the centers of the toric cap are calculated so as to adapt the angular opening of the beam of light coming from the light source and transmitted by the fourth part. In some configurations, one of the focal points of the dish is substantially merged with one of the centers of the toric cap.
  • This second part is to return the light rays coming from the source and having a large incident inside the light guide with a small incidence on the axis xx of the prism so as to reduce the incidence and to limit the reflections on the walls of the light guide.
  • a third portion 23 operates in reflection.
  • This reflection can be either a total reflection due to the difference in optical index between the light guide and the outside, or a reflection due to a reflective treatment of the walls.
  • This third part is in the form of a prism consisting of plane faces.
  • the prism can be square, rectangular or hexagonal. It has a second low edge and a second high edge. It is attached to its second low rim at the first high rim of the second part.
  • the function of this third part is to mix and guide by successive reflections on the walls of the prism the light towards the exit face of the light guide.
  • the light from the light source comprises two types of light rays.
  • the important incident rays are reflected a first time by the paraboloid 22, then by the walls of the prism 23.
  • the low incidence rays are directly reflected by the walls of the prism 23.
  • the height of the prism is sufficient to ensure a mixture correct light rays.
  • a fourth portion 24 operates in transmission. It corresponds to the exit face of the light guide and is delimited by the second high edge of the third part. Generally, this output face is a flat surface perpendicular or inclined with respect to the x-axis of the prism. It is thus possible to direct the output stream in a desired mean direction.
  • FIG. 3 represents a sectional view of a display device comprising such a lighting.
  • This light box comprises a set of point lighting sources 10 which are generally mounted on an electronic circuit 12 common to all sources. Each source is surmounted by a light guide 20 according to the invention.
  • the matrix display 30 is arranged in front of the exit faces of the different light guides.
  • a mechanical structure 40 holds the electronic circuit, the light sources, the guides and the display. As can be seen in FIG. 3, if it is desired to favor a particular direction of incidence, the guides are inclined relative to the normal yy to the display. They are therefore of different length depending on their position.
  • this type of lighting is particularly well suited to illuminate head-up viewfinder displays as described above which require both a large, homogeneous illumination and covering a pupil of given dimensions.
  • the increase in photometric efficiency of a light having light guides according to the invention can have various applications. It is of course possible to increase the luminance of the display. It is also possible, with identical luminance, to reduce either the number of light sources required or the power consumed, thus reducing the thermal stress and / or the cost of the device.

Abstract

The invention relates to the general field of light guides for a point light source (10) comprising a substantially spherical, transparent segment. The guide (20) is made of a transparent material, the external surface thereof comprises four portions: a first portion (21) which operates by transmission and corresponds to the input side of the waveguide, which is in the form of a concave toroidal dome; a second portion (22) which operates by reflection and is in the form of a rotational elliptical paraboloid; a third portion (23) which operates by reflection and is in the form of a prism consisting of planar surfaces; and a fourth portion (24) which operates by transmission and corresponds to the output side of the waveguide. The light guide according to the invention is well-suited for producing light boxes for matrix displays operating by transmission.

Description

Guide de lumière pour source de lumière ponctuelle et dispositif d'éclairage associé  Light guide for point light source and associated lighting device
Le domaine de l'invention est celui des boîtes à lumière pour dispositif de visualisation comportant un afficheur passif fonctionnant par transmission. Plus précisément, le domaine de l'invention est celui des afficheurs pour les dispositifs de visualisation dits « Tête Haute » utilisés en aéronautique et plus récemment dans le domaine automobile. The field of the invention is that of light boxes for display device comprising a passive display operating by transmission. More specifically, the field of the invention is that of displays for display devices called "Head High" used in aeronautics and more recently in the automotive field.
Un dispositif de visualisation Tête Haute est représenté en figure 1 . Il comprend principalement un afficheur 1 matriciel transparent à cristaux liquides, une boîte à lumière 2 éclairant cet afficheur, une optique de collimation 3 et un mélangeur optique 4. Le miroir 5 est un simple miroir de renvoi. L'optique de collimation 3 donne de l'image affichée une image à grande distance devant l'œil Y d'un utilisateur. Elle est schématiquement représentée par une lentille simple sur la figure 1 . Le mélangeur optique 4 assure la superposition de l'image affichée sur l'extérieur. Il est représenté par une lame mince sur la figure 1 . Le paysage extérieur est symboliquement représenté par des chevrons blancs. Il peut éventuellement être intégré au pare-brise du véhicule. A head-up display device is shown in FIG. It mainly comprises a transparent liquid crystal matrix display 1, a light box 2 illuminating this display, a collimation optics 3 and an optical mixer 4. The mirror 5 is a simple reflecting mirror. The collimating optics 3 gives the image displayed an image at a great distance in front of the eye Y of a user. It is schematically represented by a simple lens in FIG. The optical mixer 4 ensures the superposition of the image displayed on the outside. It is represented by a thin blade in FIG. The exterior landscape is symbolically represented by white chevrons. It can possibly be integrated in the windshield of the vehicle.
L'image affichée doit être visible de jour comme de nuit. Par conséquent, la boîte à lumière doit être particulièrement lumineuse pour assurer une bonne luminosité de l'image sous ensoleillement élevé. La boîte à lumière comprend généralement des sources de lumière disposées dans une enceinte diffusante et fermée par une surface diffusante. Cette surface diffusante permet à la fois de répartir uniformément la lumière sur la surface de l'afficheur et d'assurer un éclairage correct de la pupille du dispositif de visualisation. Les sources de lumière utilisées peuvent être des tubes fluorescents ou « CCFL », acronyme de « Cold Cathod Fluorescent Light ». Plus récemment, ces sources sont des diodes électroluminescentes à haute luminosité. Ces diodes présentent l'avantage d'avoir un excellent rendement, une dynamique élevée, une grande fiabilité et d'assurer une parfaite colorimétrie. Cependant, les diodes sont, par nature, des sources ponctuelles. Leur géométrie n'est donc pas très bien adaptée à l'éclairage d'imageurs plans et, le plus souvent, afin d'obtenir un éclairage homogène, une part non négligeable de l'énergie lumineuse émise par les diodes est perdue. L'objet de l'invention est de réduire ces pertes de lumière de façon importante. A cette fin, la boîte à lumière est segmentée en une pluralité de zones. Chaque zone est alors éclairée par une source de lumière collimatée dédiée à ladite zone. The displayed image must be visible day and night. Therefore, the light box must be particularly bright to ensure a good brightness of the image under high sun. The light box generally comprises light sources arranged in a diffusing chamber and closed by a diffusing surface. This diffusing surface makes it possible both to uniformly distribute the light on the surface of the display and to ensure correct illumination of the pupil of the display device. The light sources used may be fluorescent tubes or "CCFL", acronym for "Cold Cathod Fluorescent Light". More recently, these sources are light emitting diodes with high brightness. These diodes have the advantage of having excellent performance, high dynamics, high reliability and ensure perfect colorimetry. However, diodes are, by nature, point sources. Their geometry is therefore not very well suited to the illumination of flat imagers and, most often, in order to obtain homogeneous illumination, a significant part of the light energy emitted by the diodes is lost. The object of the invention is to reduce these losses of light significantly. For this purpose, the light box is segmented into a plurality of zones. Each zone is then illuminated by a collimated light source dedicated to said zone.
Plus précisément, l'invention a pour objet un guide de lumière pour source de lumière ponctuelle ou quasi-ponctuelle comportant une calotte transparente sensiblement sphérique, ledit guide étant réalisé dans un matériau transparent à la longueur d'onde d'émission de ladite source de lumière, caractérisé en ce que la surface externe dudit guide de lumière comporte quatre parties : More specifically, the subject of the invention is a light guide for a point or quasi-point light source comprising a substantially spherical transparent cap, said guide being made of a material transparent to the emission wavelength of said source of light. light, characterized in that the outer surface of said light guide comprises four parts:
- Une première partie, fonctionnant en transmission, correspondant à la face d'entrée du guide de lumière, en forme de calotte torique concave dont au moins un rayon de courbure est sensiblement égal au rayon de courbure de la calotte de ladite source de lumière ;  - A first part, operating in transmission, corresponding to the input side of the light guide, in the form of concave toric cap, at least one radius of curvature is substantially equal to the radius of curvature of the cap of said light source;
- Une seconde partie, fonctionnant en réflexion, en forme de paraboloïde elliptique, comportant un premier pourtour bas et un premier pourtour haut de plus grande circonférence, rattachée sur son pourtour bas à la première partie ;  A second portion, operating in reflection, in the form of an elliptical paraboloid, having a first low rim and a first rim of greater circumference, attached to its lower rim at the first portion;
- Une troisième partie, fonctionnant en réflexion, en forme de prisme constitué de faces planes, comportant un second pourtour bas et un second pourtour haut, rattachée sur son second pourtour bas au premier pourtour haut de la seconde partie ;  - A third part, operating in reflection, in the form of a prism consisting of flat faces, having a second low rim and a second high rim, attached to its second low rim at the first high rim of the second portion;
- Une quatrième partie fonctionnant en transmission, correspondant à la face de sortie du guide de lumière et délimitée par le second pourtour haut de la troisième partie. - A fourth part operating in transmission, corresponding to the exit face of the light guide and defined by the second high circumference of the third part.
Avantageusement, un des deux foyers du paraboloïde elliptique est confondu avec au moins un des deux centres de la calotte torique. Avantageusement, un des deux foyers du paraboloïde elliptique est à une distance prédéterminée d'au moins un des deux centres de la calotte torique, de façon à adapter l'ouverture angulaire du faisceau de lumière issue de la source de lumière et transmis par la quatrième partie. Advantageously, one of the two focal points of the elliptical dish is coincident with at least one of the two centers of the toric cap. Advantageously, one of the two foci of the elliptical dish is at a predetermined distance from at least one of the two centers of the toric cap, so as to adapt the angular aperture of the light beam from the light source and transmitted by the fourth part.
Avantageusement, le premier rayon de courbure de la calotte torique concave est sensiblement égal au rayon de courbure de la calotte de la source de lumière et le second rayon de courbure de la calotte torique concave est sensiblement égal à l'infini.  Advantageously, the first radius of curvature of the concave toric cap is substantially equal to the radius of curvature of the cap of the light source and the second radius of curvature of the concave toric cap is substantially equal to infinity.
Avantageusement, la troisième partie est à base rectangulaire ou carrée ou hexagonale.  Advantageously, the third part is rectangular or square or hexagonal.
Avantageusement, la quatrième partie est une surface plane perpendiculaire ou inclinée par rapport à la génératrice du prisme.  Advantageously, the fourth part is a flat surface perpendicular or inclined with respect to the generatrix of the prism.
L'invention concerne également une boîte à lumière comprenant une pluralité de sources de lumière ponctuelles ou quasi-ponctuelles, caractérisé en ce que chaque source de lumière comporte un guide de lumière comme défini ci-dessus, les différents guides de lumière étant jointifs. The invention also relates to a light box comprising a plurality of point or quasi-point light sources, characterized in that each light source comprises a light guide as defined above, the different light guides being joined.
Elle concerne enfin un dispositif de visualisation comportant au moins un afficheur matriciel fonctionnant par transmission et une boîte à lumière comme définie ci-dessus.  Finally, it relates to a display device comprising at least one matrix display operating by transmission and a light box as defined above.
Avantageusement, le dispositif comporte une optique de collimation et un mélangeur optique permettant de superposer l'image de l'afficheur matriciel sur un paysage extérieur.  Advantageously, the device comprises a collimation optics and an optical mixer for superimposing the image of the matrix display on an outside landscape.
L'invention sera mieux comprise et d'autres avantages apparaîtront à la lecture de la description qui va suivre donnée à titre non limitatif et grâce aux figures annexées parmi lesquelles : The invention will be better understood and other advantages will become apparent on reading the description which follows given by way of non-limiting example and by virtue of the appended figures among which:
La figure 1 déjà commentée représente un dispositif de visualisation tête haute ;  Figure 1 already commented represents a head-up display device;
La figure 2 représente une vue en coupe d'un guide de lumière selon l'invention ;  Figure 2 shows a sectional view of a light guide according to the invention;
La figure 3 représente un dispositif de visualisation comportant un ensemble de guides de lumière selon l'invention. A titre d'exemple de réalisation, la figure 2 représente une vue en coupe d'un guide de lumière 20 selon l'invention. Il est destiné à fonctionner avec une source de lumière 10 ponctuelle ou quasi-ponctuelle comportant une calotte transparente sensiblement sphérique 1 1 . Cette source est généralement une diode électroluminescente ou une diode laser. Les rayons lumineux sont représentés en pointillés sur cette figure 2. FIG. 3 represents a display device comprising a set of light guides according to the invention. As an exemplary embodiment, Figure 2 shows a sectional view of a light guide 20 according to the invention. It is intended to operate with a point or quasi-point light source 10 comprising a substantially spherical transparent cap 11. This source is generally a light emitting diode or a laser diode. The light rays are shown in dashed lines in this FIG.
Le guide de lumière 20 est réalisé dans un matériau transparent à la longueur d'onde d'émission de ladite source de lumière. Ce matériau est généralement un verre organique. Sa forme générale est celle d'un prisme à facettes. On appelle génératrice ou axe x-x du prisme un axe centré sur le prisme et parallèle aux différentes facettes du prisme. Généralement, la longueur du prisme ne dépasse pas 10 centimètres et sa largeur 1 à 2 centimètres. La surface externe du guide de lumière comporte quatre parties détaillées ci-dessous.  The light guide 20 is made of a material transparent to the emission wavelength of said light source. This material is usually an organic glass. Its general form is that of a faceted prism. The generator or axis x-x of the prism is an axis centered on the prism and parallel to the different facets of the prism. Generally, the length of the prism does not exceed 10 centimeters and its width 1 to 2 centimeters. The outer surface of the light guide has four parts detailed below.
Une première partie 21 fonctionne en transmission. Elle correspond à la face d'entrée du guide de lumière. Elle est en forme de calotte torique concave. Un tore comporte deux rayons de courbure. Généralement, un des deux rayons de courbure du tore est sensiblement égal au rayon de courbure de la calotte 1 1 de la source de lumière. La valeur du second rayon du tore est comprise entre le rayon de courbure de la calotte 1 1 et l'infini. Dans le cas de la figure 2, cette calotte torique est hémisphérique. Cette première partie est située au plus près de la calotte 1 1 de la source de lumière. La fonction optique de cette première partie est de faire en sorte que les rayons lumineux venant de la source de lumière pénètrent dans le guide de lumière avec le minimum de pertes.  A first part 21 operates in transmission. It corresponds to the entrance face of the light guide. It is shaped like a concave toric cap. A torus has two radii of curvature. Generally, one of the two radii of curvature of the torus is substantially equal to the radius of curvature of the cap 1 1 of the light source. The value of the second radius of the torus is between the radius of curvature of the cap 1 1 and infinity. In the case of Figure 2, this toric cap is hemispherical. This first part is located closer to the cap 1 1 of the light source. The optical function of this first part is to ensure that the light rays coming from the light source penetrate the light guide with the minimum of losses.
Une seconde partie 22 fonctionne en réflexion. Elle est en forme de paraboloïde elliptique de révolution. Elle comporte un premier pourtour bas et un premier pourtour haut de plus grande circonférence. Elle est rattachée sur son pourtour bas à la première partie, les distances entre les foyers du paraboloïde et les centres de la calotte torique sont calculées de façon à adapter l'ouverture angulaire du faisceau de lumière issue de la source de lumière et transmis par la quatrième partie. Dans certaines configurations, un des foyers du paraboloïde est sensiblement confondu avec un des centres de la calotte torique. La fonction de cette seconde partie est de renvoyer les rayons lumineux issus de la source et ayant une incidente importante à l'intérieur du guide de lumière avec une incidence faible sur l'axe x-x du prisme de façon à diminuer l'incidence et à limiter les réflexions sur les parois du guide de lumière. A second portion 22 operates in reflection. It is shaped like an elliptical paraboloid of revolution. It has a first low circumference and a first high circumference of greater circumference. It is attached on its lower edge to the first part, the distances between the focal points of the dish and the centers of the toric cap are calculated so as to adapt the angular opening of the beam of light coming from the light source and transmitted by the fourth part. In some configurations, one of the focal points of the dish is substantially merged with one of the centers of the toric cap. The function of this second part is to return the light rays coming from the source and having a large incident inside the light guide with a small incidence on the axis xx of the prism so as to reduce the incidence and to limit the reflections on the walls of the light guide.
Une troisième partie 23 fonctionne en réflexion. Cette réflexion peut être soit une réflexion totale due à la différence d'indice optique entre le guide de lumière et l'extérieur, soit une réflexion due à un traitement réfléchissant des parois. Cette troisième partie est en forme de prisme constitué de faces planes. Le prisme peut être à base carrée, rectangulaire ou hexagonale. Elle comporte un second pourtour bas et un second pourtour haut. Elle est rattachée sur son second pourtour bas au premier pourtour haut de la seconde partie. La fonction de cette troisième partie est de mélanger et de guider par réflexions successives sur les parois du prisme la lumière vers la face de sortie du guide de lumière. Ainsi, la lumière issue de la source de lumière comporte deux types de rayons lumineux. Les rayons d'incidente importante sont réfléchis une première fois par le paraboloïde 22, puis par les parois du prisme 23. Les rayons d'incidence faible sont directement réfléchis par les parois du prisme 23. La hauteur du prisme est suffisante pour assurer un mélange correct des rayons lumineux.  A third portion 23 operates in reflection. This reflection can be either a total reflection due to the difference in optical index between the light guide and the outside, or a reflection due to a reflective treatment of the walls. This third part is in the form of a prism consisting of plane faces. The prism can be square, rectangular or hexagonal. It has a second low edge and a second high edge. It is attached to its second low rim at the first high rim of the second part. The function of this third part is to mix and guide by successive reflections on the walls of the prism the light towards the exit face of the light guide. Thus, the light from the light source comprises two types of light rays. The important incident rays are reflected a first time by the paraboloid 22, then by the walls of the prism 23. The low incidence rays are directly reflected by the walls of the prism 23. The height of the prism is sufficient to ensure a mixture correct light rays.
Une quatrième partie 24 fonctionne en transmission. Elle correspond à la face de sortie du guide de lumière et est délimitée par le second pourtour haut de la troisième partie. Généralement, cette face de sortie est une surface plane perpendiculaire ou inclinée par rapport à l'axe x- x du prisme. On peut ainsi diriger le flux de sortie dans une direction moyenne souhaitée.  A fourth portion 24 operates in transmission. It corresponds to the exit face of the light guide and is delimited by the second high edge of the third part. Generally, this output face is a flat surface perpendicular or inclined with respect to the x-axis of the prism. It is thus possible to direct the output stream in a desired mean direction.
L'ensemble constitué d'une source de lumière ponctuelle et de son guide de lumière associée permet d'éclairer la surface 24 de façon homogène. En juxtaposant plusieurs de ces sources surmontées de leur guide, on peut ainsi éclairer une surface de grandes dimensions correspondant par exemple à la surface d'un afficheur matriciel. La figure 3 représente une vue en coupe d'un dispositif de visualisation comportant un tel éclairage. Cette boîte à lumière comporte un ensemble de sources 10 d'éclairage ponctuelles qui sont généralement montées sur un circuit électronique 12 commun à toutes les sources. Chaque source est surmontée d'un guide de lumière 20 selon l'invention. L'afficheur matriciel 30 est disposé devant les faces de sortie des différents guides de lumière. Une structure mécanique 40 maintient le circuit électronique, les sources de lumière, les guides et l'afficheur. Comme on le voit sur la figure 3, si l'on souhaite privilégier une direction d'incidence particulière, les guides sont inclinés par rapport à la normale y-y à l'afficheur. Ils sont donc de longueur différente selon leur position. The assembly consisting of a point light source and its associated light guide makes it possible to illuminate the surface 24 in a homogeneous manner. By juxtaposing several of these sources surmounted by their guide, it is possible to illuminate a surface of large dimensions corresponding for example to the surface of a matrix display. FIG. 3 represents a sectional view of a display device comprising such a lighting. This light box comprises a set of point lighting sources 10 which are generally mounted on an electronic circuit 12 common to all sources. Each source is surmounted by a light guide 20 according to the invention. The matrix display 30 is arranged in front of the exit faces of the different light guides. A mechanical structure 40 holds the electronic circuit, the light sources, the guides and the display. As can be seen in FIG. 3, if it is desired to favor a particular direction of incidence, the guides are inclined relative to the normal yy to the display. They are therefore of different length depending on their position.
Dans le domaine aéronautique, ce type d'éclairage est particulièrement bien adapté pour éclairer des afficheurs de viseurs Tête Haute tels que décrits précédemment et qui nécessitent à la fois un éclairage important, homogène et couvrant une pupille de dimensions données.  In the aeronautical field, this type of lighting is particularly well suited to illuminate head-up viewfinder displays as described above which require both a large, homogeneous illumination and covering a pupil of given dimensions.
L'augmentation de rendement photométrique d'un éclairage comportant des guides de lumière selon l'invention peut avoir diverses applications. On peut bien entendu augmenter la luminance de l'afficheur. On peut également, à luminance identique, diminuer soit le nombre de sources de lumière nécessaires, soit la puissance consommée, réduisant ainsi les contraintes thermiques et/ou le coût du dispositif. The increase in photometric efficiency of a light having light guides according to the invention can have various applications. It is of course possible to increase the luminance of the display. It is also possible, with identical luminance, to reduce either the number of light sources required or the power consumed, thus reducing the thermal stress and / or the cost of the device.

Claims

REVENDICATIONS
1 . Guide de lumière (20) pour source de lumière (10) ponctuelle ou quasi-ponctuelle comportant une calotte transparente sensiblement sphérique, ledit guide étant réalisé dans un matériau transparent à la longueur d'onde d'émission de ladite source de lumière, caractérisé en ce que la surface externe dudit guide de lumière comporte quatre parties : 1. A light guide (20) for a point or quasi-point light source (10) comprising a substantially spherical transparent cap, said guide being made of a material transparent to the emission wavelength of said light source, characterized in the outer surface of said light guide has four parts:
- Une première partie (21 ), fonctionnant en transmission, correspondant à la face d'entrée du guide de lumière, en forme de calotte torique concave dont au moins un rayon de courbure est sensiblement égal au rayon de courbure de la calotte de ladite source de lumière ;  - A first part (21), operating in transmission, corresponding to the entrance face of the light guide, in the form of a concave toric cap whose at least one radius of curvature is substantially equal to the radius of curvature of the cap of said source from light ;
- Une seconde partie (22), fonctionnant en réflexion, en forme de paraboloïde elliptique, comportant un premier pourtour bas et un premier pourtour haut de plus grande circonférence, rattachée sur son pourtour bas à la première partie ;  - A second portion (22), operating in reflection, in the form of elliptical paraboloid, having a first low rim and a first high rim of greater circumference, attached on its low rim to the first part;
- Une troisième partie (23), fonctionnant en réflexion, en forme de prisme constitué de faces planes, comportant un second pourtour bas et un second pourtour haut, rattachée sur son second pourtour bas au premier pourtour haut de la seconde partie ;  - A third portion (23), operating in reflection, in the form of a prism consisting of flat faces, having a second low rim and a second high rim, attached to its second low rim at the first high rim of the second portion;
- Une quatrième partie (24) fonctionnant en transmission, correspondant à la face de sortie du guide de lumière et délimitée par le second pourtour haut de la troisième partie.  - A fourth part (24) operating in transmission, corresponding to the exit face of the light guide and defined by the second high circumference of the third part.
2. Guide de lumière selon la revendication 1 , caractérisé en ce qu'au moins un des deux foyers du paraboloïde elliptique (22) est sensiblement confondu avec au moins un des deux centres de la calotte torique. 2. Light guide according to claim 1, characterized in that at least one of the two foci of the elliptical dish (22) is substantially coincident with at least one of the two centers of the toric cap.
3. Guide de lumière selon la revendication 1 , caractérisé en ce qu'au moins un des deux foyers du paraboloïde elliptique (22) est à une distance prédéterminée d'au moins un des deux centres de la calotte torique, de façon à adapter l'ouverture angulaire du faisceau de lumière issue de la source de lumière et transmis par la quatrième partie. A light guide according to claim 1, characterized in that at least one of the two focal points of the elliptical paraboloid (22) is at a predetermined distance from at least one of the two centers of the toric cap, to adapt the angular aperture of the light beam from the light source and transmitted by the fourth part.
4. Guide de lumière selon l'une des revendications précédentes, caractérisé en ce que le premier rayon de courbure de la calotte torique concave (21 ) est sensiblement égal au rayon de courbure de la calotte de la source de lumière et en ce que le second rayon de courbure de la calotte torique concave est sensiblement égal à l'infini. 4. Light guide according to one of the preceding claims, characterized in that the first radius of curvature of the concave toric cap (21) is substantially equal to the radius of curvature of the cap of the light source and in that the second radius of curvature of the concave toric cap is substantially equal to infinity.
5. Guide de lumière selon l'une des revendications précédentes, caractérisé en ce que la troisième partie (23) est à base rectangulaire ou carrée ou hexagonale. 5. Light guide according to one of the preceding claims, characterized in that the third portion (23) is rectangular or square or hexagonal.
6. Guide de lumière selon l'une des revendications 1 à 4, caractérisé en ce que la quatrième partie (24) est une surface plane perpendiculaire ou inclinée par rapport à la génératrice du prisme. 6. Light guide according to one of claims 1 to 4, characterized in that the fourth portion (24) is a flat surface perpendicular or inclined relative to the generatrix of the prism.
7. Boîte à lumière comprenant une pluralité de sources de lumière (10) ponctuelles ou quasi-ponctuelles, caractérisé en ce que chaque source de lumière comporte un guide de lumière (20) selon l'une des revendications précédentes, les différents guides de lumière étant jointifs. 7. A light box comprising a plurality of point or quasi-point light sources (10), characterized in that each light source comprises a light guide (20) according to one of the preceding claims, the various light guides. being joined.
8. Dispositif de visualisation comportant au moins un afficheur matriciel (30) fonctionnant par transmission et une boîte à lumière, caractérisé en ce que la boîte à lumière est selon la revendication 7. 8. Display device comprising at least one matrix display (30) operating by transmission and a light box, characterized in that the light box is according to claim 7.
9. Dispositif de visualisation selon la revendication 8, caractérisé en ce que le dispositif comporte une optique de collimation et un mélangeur optique permettant de superposer l'image de l'afficheur matriciel sur un paysage extérieur. 9. Display device according to claim 8, characterized in that the device comprises a collimation optics and an optical mixer for superimposing the image of the matrix display on an outside landscape.
PCT/EP2015/053560 2014-03-07 2015-02-20 Light guide for a point light source and associated lighting device WO2015132079A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR1400558A FR3018363B1 (en) 2014-03-07 2014-03-07 LIGHT GUIDE FOR SOURCE OF LIGHT PONCTUELLE AND LIGHTING DEVICE THEREFOR
FR1400558 2014-03-07

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6560038B1 (en) * 2001-12-10 2003-05-06 Teledyne Lighting And Display Products, Inc. Light extraction from LEDs with light pipes
US20050219840A1 (en) * 2004-03-30 2005-10-06 Holder Ronald G Apparatus and method for improved illumination area fill
US20060203486A1 (en) * 2005-03-08 2006-09-14 Samsung Electronics Co., Ltd. Illuminating unit and projection type image display apparatus using the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6560038B1 (en) * 2001-12-10 2003-05-06 Teledyne Lighting And Display Products, Inc. Light extraction from LEDs with light pipes
US20050219840A1 (en) * 2004-03-30 2005-10-06 Holder Ronald G Apparatus and method for improved illumination area fill
US20060203486A1 (en) * 2005-03-08 2006-09-14 Samsung Electronics Co., Ltd. Illuminating unit and projection type image display apparatus using the same

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FR3018363A1 (en) 2015-09-11

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