EP2410238A1 - Optical reflector consisting of a transparent blade with an undercut - Google Patents
Optical reflector consisting of a transparent blade with an undercut Download PDFInfo
- Publication number
- EP2410238A1 EP2410238A1 EP11174428A EP11174428A EP2410238A1 EP 2410238 A1 EP2410238 A1 EP 2410238A1 EP 11174428 A EP11174428 A EP 11174428A EP 11174428 A EP11174428 A EP 11174428A EP 2410238 A1 EP2410238 A1 EP 2410238A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- reflector
- blade
- focus
- optical axis
- lighting module
- Prior art date
- Legal status (The legal status 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 status listed.)
- Granted
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- 229910052782 aluminium Inorganic materials 0.000 description 1
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Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
- F21S41/30—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors
- F21S41/32—Optical layout thereof
- F21S41/322—Optical layout thereof the reflector using total internal reflection
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
- F21S41/10—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source
- F21S41/14—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by the light source characterised by the type of light source
- F21S41/141—Light emitting diodes [LED]
- F21S41/147—Light emitting diodes [LED] the main emission direction of the LED being angled to the optical axis of the illuminating device
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
- F21S41/20—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by refractors, transparent cover plates, light guides or filters
- F21S41/28—Cover glass
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
- F21S41/20—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by refractors, transparent cover plates, light guides or filters
- F21S41/285—Refractors, transparent cover plates, light guides or filters not provided in groups F21S41/24 - F21S41/2805
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S41/00—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
- F21S41/30—Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors
- F21S41/32—Optical layout thereof
- F21S41/321—Optical layout thereof the reflector being a surface of revolution or a planar surface, e.g. truncated
Definitions
- the invention relates to a lighting module for a vehicle headlamp, more particularly to a lighting module comprising a reflector with a first and second focus, such as an elliptical reflector, a blade of transparent material with a slice disposed at near the second focus and intended to serve as a folder, and a dioptric element, for example a convergent lens.
- a reflector with a first and second focus such as an elliptical reflector
- a blade of transparent material with a slice disposed at near the second focus and intended to serve as a folder
- a dioptric element for example a convergent lens.
- the slice or upper surface of the transparent blade is generally flat and aligned with the optical axis and covered with a reflective coating.
- the leading edge of the wafer i.e., the edge of the wafer on the side of the lens is in the vicinity of the second focus.
- the reflective coating on the upper edge of the transparent plate consists for example of a deposit of vacuum deposited aluminum with a thickness ranging from less than a micron to a few tens of microns.
- the reflective coating constitutes a "folder” able to "fold” by reflection the rays coming from the upper reflector to ensure a cutoff of the "code” type beam thus generated.
- the rays from the lower reflector are added to those of the upper reflector to provide the "road" function.
- the bender thus formed has the advantage of being extremely thin which is particularly interesting in "road” function to minimize the areas of low intensity between the beam from the upper reflector and the beam from the lower reflector. Such fineness of bending is difficult to achieve by means of a reflective plate, at least in an industrial logic and at a reasonable price.
- the blade serving as a support for the reflective coating has the disadvantage of having a refractive index greater than 1 and hence of refracting the rays coming from the lower reflector.
- the use of a transparent support blade therefore generates a slight deviation of the rays and hence a loss of efficiency and lighting quality.
- the rays coming from the reflector and entering the blade with a large angle of incidence and then reflected by the reflective coating emerge from the blade at a distance from the reflective edge of the blade and with an always important angle of incidence. .
- These rays will meet the lens with a significant angle of incidence and therefore suffer losses called Fresnel, also called partial glassy reflections.
- the object of the invention is to propose a lighting module that is more efficient than the modules mentioned above.
- the object of the invention relates to a lighting module for a motor vehicle headlamp, comprising: a first reflector with a reflective surface, with at least a first focus for a light source and a second focus; a dioptric element with an optical axis, arranged to receive the light rays from said light source and to transmit the light rays reaching it in a light beam; a blade of transparent material disposed between said reflector and said dioptric element so as to present a wafer, forming a folder capable of reflecting a part of the rays reflected by the reflective surface of the first reflector towards a portion of the dioptric element; the first reflector, the dioptric element, the edge of the blade being arranged to form a beam.
- said generally flat slice is inclined toward said reflector with respect to the optical axis of the dioptric element.
- the dioptric element may be a convergent lens.
- the reflecting surface of the first reflector is such that said reflecting surface is able to reflect the light rays emitted by the light source from said first focus, the reflected rays propagating toward said second focus, either before they reach said blade, or after refraction in said blade.
- the direction of the rays reflected towards the second focus after refraction the reflecting surface of the first reflector is corrected according to the blade so that rays emitted by the light source of the first reflector pass approximately through the second focus. after reflection on said corrected reflecting surface and refraction when passing through said blade.
- the reflective surface is corrected with respect to a reflective surface where the reflected rays are directed to the second focus before refraction.
- the wafer may comprise a flat portion or be completely planar.
- the presence of a reflective coating on the wafer is not essential. Indeed, it is possible to perform the folding function without the presence of reflective coating, this function being based on the principle of total reflection at the diopter formed by the change of refractive index between the transparent material of the blade and the ambient air at the level of the slice.
- the edge of the edge of the blade on the side of the dioptric element is approximately at said second focus.
- the optical axis of the dioptric element passes through the second focus.
- the dioptric element is convergent and has a focus disposed about on the second focus.
- the edge of the blade forms an angle ⁇ with the optical axis of the dioptric element between 1 ° and 7 °, preferably between 2 ° and 5 °, more preferably still between 3 ° and 5 °. ° and 5 °.
- the blade is located exclusively on the optical axis side of the dioptric element where the reflector is located. This allows for example to use a second reflector above the first reflector.
- the edge of the blade is provided with a reflective coating.
- the blade has two main faces parallel and perpendicular to the optical axis of the dioptric element.
- the blade has a face opposite to the edge serving as a folder, said opposite face being inclined with respect to a perpendicular to the main faces, the inclination of said opposite face being oriented so as to reduce the surface of the main face facing the reflector.
- This provides a draft angle to be able to demold the blade more easily during its design. This is particularly the case when the blade is made of glass, because it is difficult or impossible to use a movement in the molding tool.
- the face of the blade opposite to the edge serving as a folder forms an angle with a perpendicular to the main faces between 1 ° and 7 °, preferably between 2 ° and 5 °, more preferably still between 3 ° and 5 °.
- the optical axis of the first reflector forms an angle with the optical axis of the dioptric element, preferably an angle of more than 10 °, more preferably an angle of more than 20 °. , more preferably still an angle of more than 30 °.
- the proposed measurements are particularly interesting when the reflector is inclined with respect to the optical axis of the module. Indeed, in this arrangement, the rays enter the blade with a greater angle of incidence, so that the compensation made by the proposed measures can limit the dispersion of rays.
- the first reflector is arranged so that its reflecting surface moves away from the optical axis of the dioptric element when said reflective surface approaches its first focus.
- the first focus of the reflecting surface is located below the optical axis of the dioptric element.
- this arrangement implies a substantial angle between the optical axis of the reflector and the optical axis of the module. It follows that the rays coming from the reflector enter the blade with a large angle of incidence, the compensation made by the proposed measures thus making it possible to limit the dispersion of the rays.
- the module comprises a second reflector with a reflective surface, with at least a first focus for a light source, a second focus and an optical axis passing through said first and second focus, said surface reflector being adapted to reflect the light rays emitted by said light source from said first focus to said second focus, said second focus being approximately coincident with the second focus of the first reflector, the optical axis of the first reflector forming an angle with the axis optical element of the dioptric element, the first and second reflectors being oriented relative to their respective optical axes so that the reflective surface of the second reflector is vis-à-vis the outer surface of the first reflector, this outer surface being the opposite surface to the reflective surface of the first reflector.
- the reflective face of the second reflector is facing the back of the second reflector.
- a wall disposed adjacent to the edge of the transparent blade, in a plane passing approximately through said wafer, said wall having a reflecting face oriented towards the first reflector and serving as a folder for rays reflected by the reflective surface of the first reflector.
- the plane containing this wall is parallel to the optical axis of the dioptric element and passes through the rear edge of the reflective wafer of the blade.
- the light source or sources are electroluminescent diodes.
- optical elements are illustrated in the figures in a simplified manner with perfect matching of the focal points and optical axes for the sake of clarity of presentation. Such matches are not to be interpreted strictly, since in practice there may be slight deviations due to the imperfect nature of certain elements, mounting tolerance and / or to correct some effects related to imperfection of certain optical elements. The same applies to the light sources which are represented in a specific way, whereas it is clear that in practice these light sources are not perfectly punctual and have a light emission surface that has been chosen here. voluntarily not to represent.
- FIG 1 is schematically illustrated in perspective a lighting module according to the invention. It comprises a convergent lens 4 with a focus 24 and an optical axis 2 passing through the focus.
- a transparent plate 6 is disposed generally perpendicularly to the optical axis 2, or generally vertically in the half-space delimited by a horizontal median plane passing through the optical axis 2.
- the blade has an upper edge 26 comprising the optical axis 2 and passing at least approximately through the plane in question.
- the top edge 26 is covered with a reflective coating. This coating is applied exclusively to the wafer 26, leaving the other faces of the blade transparent.
- the blade is arranged so that the front edge is at the focus 24.
- the wafer 26 has a projection at its median corresponding to the optical axis 2. The function of the jump will be explained further later.
- the blade is made of transparent material such as glass or any other transparent material, for example PMMA (polymethyl methacrylate).
- edge 26 of the blade can perform the folding function without the presence of a reflective coating, and this by the use of the principle of total reflection on a diopter formed by the interface between two media index of different refraction. In this case, it will be necessary to ensure that the rays meet the diopter formed by the wafer with an angle of incidence greater than the limit angle of total reflection.
- the module also comprises a first reflector 10 in the lower half-space. It is represented schematically by its reflective surface. This surface has in this example an approximate ellipsoid profile, for example symmetrical in rotation about its optical axis 20. It comprises a first focus 22 for receiving a light source and a second focus coinciding with the focus 24 of the lens 4
- the optical axis 20 of the first reflector forms an angle with the optical axis 2 which is between 30 ° and 60 °, preferably between 40 ° and 50 °.
- the light source mainly illuminates in a half-space delimited by the transverse plane comprising the optical axis 20 of the reflector and is preferably of the electroluminescent diode type.
- the module also comprises a second reflector 8 represented by its reflecting surface. It is composed of two reflecting sub-surfaces of symmetrical elliptical profile in revolution with respect to the respective optical axes 12 and 14. Each reflective sub-surface includes a first focus 16 or 18 for receiving a light source and a second focus coinciding with focus 24 of the lens and the second focus of the first reflector.
- the reflecting surface of the second reflector 8 consists of the juxtaposition of the two sub-surfaces in a half-space delimited by a plane passing through the respective optical axes 12 and 14 and the optical axis 2 of the lens 4, so as to form a cavity doubly concave adapted to reflect the light rays from the first foci 16 and 18 to the second focus 24.
- the two respective optical axes 12 and 14 form an acute angle between them and each form an equal angle with the optical axis 2 of the lens and module.
- the lighting module also comprises a reflective plate 9 on its two faces and disposed approximately in the plane passing through the optical axes 12 and 14 of the second reflector and the reflecting edge 26 of the blade 6. It is disposed adjacent or almost -Adjacent to the rear edge of the wafer and extends to a distance from this rear edge.
- the rear edge of the plate 9 reaches approximately the height of the intersection of the reflecting surface of the first reflector 10 with said plane. More specifically, the profile of the rear edge of the reflective plate 9 is V-shaped whose tip is aligned with the optical axis and symmetry 2 of the module and directed rearwardly, so that the reflecting surface of the plate covers a major part of the area defined by the intersection of the reflective surface of the first reflector with the plane.
- the reflective plate 9 plays the role of complementary folder and will be explained later.
- optical axes 12 and 14 of the reflective sub-surfaces of the second reflector 8 need not be included in the horizontal median plane. Indeed, they can form a certain angle with this plane.
- FIG. 2 A sectional view and optical principle of the device of the figure 1 is illustrated in the figure 2 .
- it has been chosen to assimilate the second reflector to a single reflective surface with a single first focus and a single light source. This simplification does not alter the operating principle of the second reflector comprising two reflecting sub-surfaces and two light sources.
- the second reflector 8 generates with its light source or sources 16 and 18 a cut-off beam ensuring for example a lighting function of the "code" type. Indeed, the majority of the rays emitted by the light source are reflected by the reflecting surface of the second reflector 8 to the second focus 24 and are transmitted by the lens in a beam of substantially parallel rays. Such a ray is illustrated by a solid line from the light source 16, 18 to the Through the reflective surface and the second focal point 24, some of the rays, especially those emitted from a front lateral zone of the light source, meet the folder 26 at the rear of the focus 24. They are reflected or "folded" towards a upper part of the lens with an angle of incidence as they come out of the lens inclined slightly downwards.
- the folder thus plays the role of a cache in a conventional projection system and the projection of its edge forms the horizontal cut of the projected beam, this cutoff being useful in particular for a lighting function of the "code” type.
- the folder comprises a projection at the front edge, so-called cutting edge, so that the cut is higher on one side than the other of the vertical median plane in order to project a cut. beam type "code" in accordance with the legislation.
- the figure 3 is a view similar to that of the figure 2 where among the two reflectors, only the lower reflector, namely the first reflector, is illustrated.
- This view is enlarged and illustrates certain optical features of the module according to the invention.
- a first ray interrupted and corresponding to that of the figure 2 is illustrated. It is emitted by the light source 22, is reflected by the reflective surface, penetrates the transparent plate 6 and undergoes a first refraction, passes through the blade, passes through the focus 24, leaves the blade and undergoes a second refraction before meeting the lens in its upper half.
- a second ray is shown in solid lines. It is emitted by an off-center zone of the light source 22 and is reflected towards an area of the folder slightly behind the second focal point 24.
- the upper edge of the blade forming the folder is inclined from the cutting edge towards the bottom of the module in order to further concentrate the rays reflected by the folder.
- the figure 4 is an enlarged view of the top of the blade.
- the upper edge 26 included in the horizontal median plane is illustrated in solid lines.
- the inclined upper edge 36 is shown in broken lines. It has a draft angle ⁇ relative to the horizontal median plane. This angle corresponds to a clearance of height d at the rear face of the blade.
- a ray 28 from the first reflector 10 and penetrating the blade is illustrated. It is refracted and undergoes a first deflection 30.
- the outgoing ray 40 undergoes a second refraction and forms an angle ⁇ 'with the normal to the front face of the blade which is less than the value ⁇ of the same incident ray reflected by the inclined bender 36. Because of these two effects, the Outgoing ray 40 will meet the lens at a lower incident angle and at a point closer to the optical axis. The projected beam from such rays will therefore be closer to the horizontal and provide higher photometric illumination due to lower losses by glassy reflections, especially on the front face of the blade and on the faces of the lens.
- the material of the blade will preferably be glass as opposed to plastic materials for reasons of temperature resistance. Indeed, the presence of the lens has the effect that the external sunlight can concentrate via the lens at the focus 24 and overheat the material of the blade.
- the edge of the blade opposite the edge serving as a folder may also be similarly inclined, and this symmetrically so as to reduce the height of the rear face of a given value. Although this slice of the blade does play no role from the point of view of optics, such inclination or clearance angle simplifies the shaping of the blade by simplifying demolding in a direction perpendicular to the front and rear faces. The optical faces can then be surfaced to ensure flatness and optical qualities.
- the reflective surface of the first reflector is corrected to compensate for the first refraction to which the rays are subjected upon entry into the blade.
- the calculation of the correction of the surface will be described below in relation to the figure 5 .
- the calculation is based on the application of the Huygens principle and Fermat's optical path principle.
- the light spreads from one to the next, the set of points of equal light disturbance being called the wave surface.
- Each point of this surface reached by light behaves like a secondary source that emits spherical wavelets in an isotropic medium.
- the envelope surface of these wavelets forms a new wave surface.
- n vs / v
- c and v are the speed of light in the vacuum and in the medium, respectively.
- the optical path is the path traveled by the light traveled in a vacuum during the propagation time in the medium:
- s denotes the curvilinear abscissa along the path traveled in the middle between points A and B, and AB the length of the path traveled between A and B.
- the Fermat principle is stated: between two points A and B, reached by the light, the optical path followed along the path is stationary.
- K which is the optical path from O to F
- the vector FP is known since the points F and P are known, the vector i has been calculated on the basis of the above-mentioned calculation and ⁇ is known, it is then sufficient to set a constant K which is suitable for then calculating the value of p and deducing a point from the surface for a vector r given.
- K is suitable for then calculating the value of p and deducing a point from the surface for a vector r given.
- the skilled person will have no difficulty in implementing such a calculation including numerical iterative calculation methods.
- the reflector is corrected so as to transform a spherical wave surface from a source point F to the surface of the emitter into a spherical wave surface in the material of the blade, centering the second focus 24, this second focus being located in the material of the blade in the vicinity of its front exit face and its upper face (slice).
- the elliptical reflective surface correction is applicable to various configurations, including the configuration of the reflector 10 of the present invention, as well as to a conventional configuration as shown in broken line at the end of FIG. figure 5 .
- the correction does not necessarily have to be made on the entire reflective surface but essentially on the area reflecting the rays that will form the central part of the beam.
- the figure 6 illustrates an elliptical reflector configuration in a half-space and whose surface is generally oriented towards the optical axis of the module, showing in particular the effect of the reflective surface correction.
- it illustrates a lighting module configuration with two elliptical reflectors 8 and 42 in opposite half-spaces and whose reflective surfaces are both directed towards the optical axis 2 of the module.
- the optical axes of the reflectors are slightly inclined to provide a space for cooling the light sources 16, 18 and 44.
- a first ray from the light source 44 and reflected at a point A is shown in solid lines.
- the broken line associated with the solid line illustrates the optical path that would follow the ray if the reflecting surface was not corrected according to the transparent blade 6; namely, this ray would be refracted as it enters the blade and would be deflected from the second focus 24.
- a second ray from the light source 44 and reflected at a point B closer to the optical axis of the reflecting surface is shown in a line. full. This grazing ray and directed towards the hearth 24 will meet the space dedicated to cooling and get lost instead of penetrating the blade. In this configuration, some of the rays will be lost in the cooling radiator of the light sources. This situation is all the more true as the surface of the reflector is corrected.
- this correction has the effect of reflecting the rays from the light source so as to have a deviation from the second focus, this deviation being such that the rays are oriented towards a point at the rear of the second focus, which intensifies the problem of loss of rays in the space needed to cool the light sources.
- the figure 7 illustrates the effect of reflective surface correction for an elliptical reflector configuration in a half-space and whose surface is generally opposite to the optical axis of the module.
- a first ray coming from the light source 22 and reflected at a point A of the corrected reflecting surface is shown in solid lines. In the absence of correction of the surface, this ray would point to the second focus 24 but would be deflected when it enters the blade and would pass below the focus. This line is illustrated in broken lines.
- the reflector about 180 ° on its optical axis has on the one hand to minimize or even eliminate the thickness of the dead volume adjacent to the rear edge of the folder, and secondly tilt the rays reflected by the reflector so that most of them do not get lost in building elements of the module.
- the correction of the reflective surface is all the more interesting in this configuration that the average angle of incidence on the rear face of the blade is important.
- a second ray coming from the light source and reflected by a point B further from the optical axis of the reflector is also illustrated. This spoke will meet the complementary folder 9 so as to be returned to the blade and participate in the production of ambient light beam.
- the preferred light source is of the electroluminescence diode type.
- Such a source illuminates in a half-space but concentrates a major part of the lighting power in a cone centered on its main illumination axis (that is to say a perpendicular to the optical axis of the reflector), so that the configuration of the figure 7 will allow the spokes forming most of the lighting power to work optimally.
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- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Optics & Photonics (AREA)
- Non-Portable Lighting Devices Or Systems Thereof (AREA)
Abstract
Description
L'invention a trait à un module d'éclairage pour projecteur véhicule, plus particulièrement à un module d'éclairage comprenant un réflecteur avec un premier et second foyer, tel qu'un réflecteur elliptique, une lame en matériau transparent avec une tranche disposée à proximité du second foyer et destinée à servir de plieuse, et un élément dioptrique, par exemple une lentille convergente.The invention relates to a lighting module for a vehicle headlamp, more particularly to a lighting module comprising a reflector with a first and second focus, such as an elliptical reflector, a blade of transparent material with a slice disposed at near the second focus and intended to serve as a folder, and a dioptric element, for example a convergent lens.
Pour créer des coupures dans les faisceaux, il est connu d'utiliser des caches horizontaux réfléchissants appelés « plieuse », comme par exemple dans
De plus, la lame servant du support au revêtement réfléchissant présente l'inconvénient d'avoir un indice de réfraction supérieure à 1 et, partant, de réfracter les rayons provenant du réflecteur inférieur. L'utilisation d'une lame transparente support génère par conséquent une légère déviation des rayons et, partant, une perte de rendement et de qualité d'éclairage. Les rayons provenant du réflecteur et entrant dans la lame avec un angle d'incidence important et qui sont ensuite réfléchis par le revêtement réfléchissant ressortent de la lame à une certaine distance de la tranche réfléchissante de la lame et avec un angle d'incidence toujours important. Ces rayons vont rencontrer la lentille avec un angle d'incidence important et vont donc subir des pertes dites de Fresnel, encore appelées réflexions vitreuses partielles.In addition, the blade serving as a support for the reflective coating has the disadvantage of having a refractive index greater than 1 and hence of refracting the rays coming from the lower reflector. The use of a transparent support blade therefore generates a slight deviation of the rays and hence a loss of efficiency and lighting quality. The rays coming from the reflector and entering the blade with a large angle of incidence and then reflected by the reflective coating emerge from the blade at a distance from the reflective edge of the blade and with an always important angle of incidence. . These rays will meet the lens with a significant angle of incidence and therefore suffer losses called Fresnel, also called partial glassy reflections.
L'invention a pour but de proposer un module d'éclairage plus performant que les modules cités précédemment.The object of the invention is to propose a lighting module that is more efficient than the modules mentioned above.
L'objet de l'invention concerne un module d'éclairage pour un projecteur de véhicule automobile, comprenant: un premier réflecteur avec une surface réfléchissante, avec au moins un premier foyer pour une source lumineuse et un second foyer; un élément dioptrique avec un axe optique, disposé de manière à recevoir les rayons lumineux de ladite source lumineuse et à transmettre les rayons lumineux l'atteignant en un faisceau lumineux; une lame en matériau transparent disposée entre ledit réflecteur et ledit élément dioptrique de manière à présenter une tranche, formant une plieuse apte à réfléchir une partie des rayons réfléchis par la surface réfléchissante du premier réflecteur vers une partie de l'élément dioptrique; le premier réflecteur, l'élément dioptrique, la tranche de la lame étant agencés de manière à former un faisceau. Selon l'invention ladite tranche généralement plane est inclinée vers ledit réflecteur par rapport à l'axe optique de l'élément dioptrique. L'élément dioptrique peut être une lentille convergente.The object of the invention relates to a lighting module for a motor vehicle headlamp, comprising: a first reflector with a reflective surface, with at least a first focus for a light source and a second focus; a dioptric element with an optical axis, arranged to receive the light rays from said light source and to transmit the light rays reaching it in a light beam; a blade of transparent material disposed between said reflector and said dioptric element so as to present a wafer, forming a folder capable of reflecting a part of the rays reflected by the reflective surface of the first reflector towards a portion of the dioptric element; the first reflector, the dioptric element, the edge of the blade being arranged to form a beam. According to the invention, said generally flat slice is inclined toward said reflector with respect to the optical axis of the dioptric element. The dioptric element may be a convergent lens.
Ces mesures ont pour effet de modifier la géométrie de réflexion au sein de la lame et de rapprocher de l'axe optique les rayons se propageant dans la lame et réfléchis par la plieuse. Ceci permet de concentrer les rayons vers l'axe optique. Le rendement du faisceau et son intensité sont ainsi augmentés.These measurements have the effect of modifying the reflection geometry within the blade and to bring closer to the optical axis rays propagating in the blade and reflected by the folder. This makes it possible to focus the rays towards the optical axis. The output of the beam and its intensity are thus increased.
La surface réfléchissante du premier réflecteur est telle que ladite surface réfléchissante est apte à réfléchir les rayons lumineux émis par la source lumineuse partant dudit premier foyer, les rayons réfléchis se propageant vers ledit second foyer, soit avant qu'ils n'atteignent ladite lame, soit après réfraction dans ladite lame. Dans le second cas, direction des rayons réfléchis vers le second foyer après réfraction, la surface réfléchissante du premier réflecteur est corrigée en fonction de la lame de manière à ce que des rayons émis par la source lumineuse du premier réflecteur passent approximativement par le second foyer après réflexion sur ladite surface réfléchissante corrigée et réfraction au passage dans ladite lame. La surface réfléchissante est corrigée par rapport à une surface réfléchissante où les rayons réfléchis sont dirigés vers le second foyer avant réfraction.The reflecting surface of the first reflector is such that said reflecting surface is able to reflect the light rays emitted by the light source from said first focus, the reflected rays propagating toward said second focus, either before they reach said blade, or after refraction in said blade. In the second case, the direction of the rays reflected towards the second focus after refraction, the reflecting surface of the first reflector is corrected according to the blade so that rays emitted by the light source of the first reflector pass approximately through the second focus. after reflection on said corrected reflecting surface and refraction when passing through said blade. The reflective surface is corrected with respect to a reflective surface where the reflected rays are directed to the second focus before refraction.
La tranche peut comprendre une portion plane ou être totalement plane.The wafer may comprise a flat portion or be completely planar.
La présence d'un revêtement réfléchissant sur la tranche n'est pas essentielle. En effet, il est possible d'assurer la fonction de plieuse sans la présence de revêtement réfléchissant, cette fonction étant basée sur le principe de réflexion totale au dioptre formé par le changement d'indice de réfraction entre le matériau transparent de la lame et l'air ambiant au niveau de la tranche.The presence of a reflective coating on the wafer is not essential. Indeed, it is possible to perform the folding function without the presence of reflective coating, this function being based on the principle of total reflection at the diopter formed by the change of refractive index between the transparent material of the blade and the ambient air at the level of the slice.
Selon un mode avantageux de l'invention, le bord de la tranche de la lame du côté de l'élément dioptrique est approximativement au niveau dudit second foyer.According to an advantageous embodiment of the invention, the edge of the edge of the blade on the side of the dioptric element is approximately at said second focus.
Préférentiellement l'axe optique de l'élément dioptrique passe par le second foyer. L'élément dioptrique est convergent et présente un foyer disposé environ sur le second foyer.Preferably, the optical axis of the dioptric element passes through the second focus. The dioptric element is convergent and has a focus disposed about on the second focus.
Selon un autre mode avantageux de l'invention, la tranche de la lame forme un angle β avec l'axe optique de l'élément dioptrique compris entre 1 ° et 7°, préférentiellement entre 2° et 5°, plus préférentiellement encore entre 3° et 5°.According to another advantageous embodiment of the invention, the edge of the blade forms an angle β with the optical axis of the dioptric element between 1 ° and 7 °, preferably between 2 ° and 5 °, more preferably still between 3 ° and 5 °. ° and 5 °.
Selon un encore autre mode avantageux de l'invention, la lame est située exclusivement du côté de l'axe optique de l'élément dioptrique où se trouve le réflecteur. Cela permet par exemple d'utiliser un second réflecteur au-dessus du premier réflecteur.According to another advantageous embodiment of the invention, the blade is located exclusively on the optical axis side of the dioptric element where the reflector is located. This allows for example to use a second reflector above the first reflector.
Selon un encore autre mode avantageux de l'invention, la tranche de la lame est pourvue d'un revêtement réfléchissant.According to yet another advantageous embodiment of the invention, the edge of the blade is provided with a reflective coating.
Selon un encore autre mode avantageux de l'invention, la lame présente deux faces principales parallèles et perpendiculaires à l'axe optique de l'élément dioptrique.According to another advantageous embodiment of the invention, the blade has two main faces parallel and perpendicular to the optical axis of the dioptric element.
Selon un encore autre mode avantageux de l'invention, la lame présente une face opposée à la tranche servant de plieuse, ladite face opposée étant inclinée par rapport à une perpendiculaire aux faces principales, l'inclinaison de ladite face opposée étant orientée de manière à réduire la surface de la face principale en regard du réflecteur. Cela permet d'obtenir un angle de dépouille pour pouvoir démouler la lame plus facilement lors de sa conception. C'est notamment le cas lorsque la lame est en verre, car il est difficile voir impossible d'utiliser un mouvement dans l'outil de moulage. Préférentiellement, la face de la lame opposée à la tranche servant de plieuse forme un angle avec une perpendiculaire aux faces principales compris entre 1 ° et 7°, préférentiellement entre 2° et 5°, plus préférentiellement encore entre 3° et 5°.According to another advantageous embodiment of the invention, the blade has a face opposite to the edge serving as a folder, said opposite face being inclined with respect to a perpendicular to the main faces, the inclination of said opposite face being oriented so as to reduce the surface of the main face facing the reflector. This provides a draft angle to be able to demold the blade more easily during its design. This is particularly the case when the blade is made of glass, because it is difficult or impossible to use a movement in the molding tool. Preferably, the face of the blade opposite to the edge serving as a folder forms an angle with a perpendicular to the main faces between 1 ° and 7 °, preferably between 2 ° and 5 °, more preferably still between 3 ° and 5 °.
Selon un encore autre mode avantageux de l'invention, l'axe optique du premier réflecteur forme un angle avec l'axe optique de l'élément dioptrique, préférentiellement un angle de plus de 10°, plus préférentiellement un angle de plus de 20°, plus préférentiellement encore un angle de plus de 30°. Les mesures proposées sont particulièrement intéressantes lorsque le réflecteur est incliné par rapport à l'axe optique du module. En effet, dans cette disposition, les rayons entrent dans la lame avec un angle d'incidence plus important, si bien que la compensation opérée par les mesures proposées permet de limiter la dispersion des rayons.According to another advantageous embodiment of the invention, the optical axis of the first reflector forms an angle with the optical axis of the dioptric element, preferably an angle of more than 10 °, more preferably an angle of more than 20 °. , more preferably still an angle of more than 30 °. The proposed measurements are particularly interesting when the reflector is inclined with respect to the optical axis of the module. Indeed, in this arrangement, the rays enter the blade with a greater angle of incidence, so that the compensation made by the proposed measures can limit the dispersion of rays.
Selon un encore autre mode avantageux de l'invention, le premier réflecteur est disposé de manière à ce que sa surface réfléchissante s'éloigne de l'axe optique de l'élément dioptrique lorsque ladite surface réfléchissante se rapproche de son premier foyer. Par exemple, lorsque l'axe optique de l'élément dioptrique est horizontal, le premier foyer de la surface réfléchissante est situé dessous l'axe optique de l'élément dioptrique. D'une manière générale, cette disposition implique un angle substantiel entre l'axe optique du réflecteur et l'axe optique du module. Il s'en suit que les rayons provenant du réflecteur entrent dans la lame avec un angle d'incidence important, la compensation opérée par les mesures proposées permettant ainsi de limiter la dispersion des rayons.According to yet another advantageous embodiment of the invention, the first reflector is arranged so that its reflecting surface moves away from the optical axis of the dioptric element when said reflective surface approaches its first focus. For example, when the optical axis of the dioptric element is horizontal, the first focus of the reflecting surface is located below the optical axis of the dioptric element. In general, this arrangement implies a substantial angle between the optical axis of the reflector and the optical axis of the module. It follows that the rays coming from the reflector enter the blade with a large angle of incidence, the compensation made by the proposed measures thus making it possible to limit the dispersion of the rays.
Selon un encore autre mode avantageux de l'invention, le module comprend un deuxième réflecteur avec une surface réfléchissante, avec au moins un premier foyer pour une source lumineuse, un second foyer et un axe optique passant par lesdits premier et second foyers, ladite surface réfléchissante étant apte à réfléchir les rayons lumineux émis par ladite source lumineuse parant dudit premier foyer vers ledit second foyer, ledit second foyer étant approximativement confondu avec le second foyer du premier réflecteur, l'axe optique du premier réflecteur formant un angle avec l'axe optique de l'élément dioptrique, les premier et deuxième réflecteurs étant orientés par rapport à leurs axes optiques respectifs de manière à ce que la surface réfléchissante du deuxième réflecteur soit en vis-à-vis de la surface externe du premier réflecteur, cette surface externe étant la surface opposée à la surface réfléchissante du premier réflecteur. Par exemple, la face réfléchissante du deuxième réflecteur est face au dos du deuxième réflecteur.According to yet another advantageous embodiment of the invention, the module comprises a second reflector with a reflective surface, with at least a first focus for a light source, a second focus and an optical axis passing through said first and second focus, said surface reflector being adapted to reflect the light rays emitted by said light source from said first focus to said second focus, said second focus being approximately coincident with the second focus of the first reflector, the optical axis of the first reflector forming an angle with the axis optical element of the dioptric element, the first and second reflectors being oriented relative to their respective optical axes so that the reflective surface of the second reflector is vis-à-vis the outer surface of the first reflector, this outer surface being the opposite surface to the reflective surface of the first reflector. For example, the reflective face of the second reflector is facing the back of the second reflector.
Selon un encore autre mode avantageux de l'invention, comprend une paroi disposée adjacente à la tranche de la lame transparente, dans un plan passant approximativement par ladite tranche, ladite paroi ayant une face réfléchissante orientée vers le premier réflecteur et servant de plieuse pour des rayons réfléchis par la surface réfléchissante du premier réflecteur. Préférentiellement, le plan contenant cette paroi est parallèle à l'axe optique de l'élément dioptrique et passe par le bord arrière de la tranche réfléchissante de la lame.According to still another advantageous embodiment of the invention, comprises a wall disposed adjacent to the edge of the transparent blade, in a plane passing approximately through said wafer, said wall having a reflecting face oriented towards the first reflector and serving as a folder for rays reflected by the reflective surface of the first reflector. Preferably, the plane containing this wall is parallel to the optical axis of the dioptric element and passes through the rear edge of the reflective wafer of the blade.
Préférentiellement, la ou les sources lumineuses sont des diodes électrolum inescentes.Preferably, the light source or sources are electroluminescent diodes.
D'autres caractéristiques et avantages de la présente invention seront mieux compris à l'aide de la description et des dessins parmi lesquels :
- La
figure 1 est une vue en perspective d'un mode de réalisation d'un module d'éclairage selon l'invention. - La
figure 2 est une vue en coupe du mode de réalisation illustré enfigure 1 ,avec tracé de rayons.. - La
figure 3 est une vue schématisant le fonctionnement du réflecteur inférieur du module illustré enfigure 2 . - La
figure 4 est une vue agrandie de la lame d'un module d'éclairage selon l'invention. - La
figure 5 est une vue d'un module d'éclairage selon l'invention illustrant les points de référence, le référentiel et les vecteurs utilisés pour un exemple de calcul de la surface du réflecteur. - La
figure 6 est une première vue illustrant l'impact de la correction du réflecteur. - La
figure 7 est une seconde vue illustrant l'impact de la correction du réflecteur.
- The
figure 1 is a perspective view of an embodiment of a lighting module according to the invention. - The
figure 2 is a sectional view of the embodiment illustrated in FIG.figure 1 , with ray trace .. - The
figure 3 is a schematic view of the operation of the lower reflector of the module illustrated infigure 2 . - The
figure 4 is an enlarged view of the blade of a lighting module according to the invention. - The
figure 5 is a view of a lighting module according to the invention illustrating the reference points, the reference frame and the vectors used for an example of calculation of the surface of the reflector. - The
figure 6 is a first view illustrating the impact of reflector correction. - The
figure 7 is a second view illustrating the impact of reflector correction.
On comprend dans la description de l'invention les termes « avant », « arrière », « haut », « bas », « supérieur » ou « inférieur » d'après la position du module d'éclairage selon les figures et une fois intégré dans un projecteur et monté sur un véhicule en mode de fonctionnement conventionnel. Il est rappelé que le module pourrait être monté et utilisé dans d'autres positions et/ou orientations sans pour autant s'éloigner de l'invention. Les termes sus mentionnés sont donc à interpréter de manière relative et non absolue.In the description of the invention, the terms "front", "back", "top", "bottom", "upper" or "bottom" are understood according to the position of the lighting module according to the figures and once integrated in a projector and mounted on a vehicle in conventional operating mode. It is recalled that the module could be mounted and used in other positions and / or orientations without departing from the invention. The terms mentioned above are therefore to be interpreted in a relative and not absolute manner.
Il est également à noter que les éléments optiques sont illustrés aux figures de manière simplifiée avec correspondance parfaite des foyers et axes optiques pour des raisons de clarté d'exposé. De telles correspondances ne sont pas à interpréter de manière stricte sachant qu'en pratique, il peut y avoir de légères déviations en raison de la nature imparfaite de certains éléments, de tolérance de montage et/ou afin de corriger certains effets liés à l'imperfection de certains éléments optiques. Il en va de même pour les sources lumineuses qui sont représentées de manière ponctuelle alors qu'il est clair qu'en pratique ces sources lumineuses ne sont pas parfaitement ponctuelles et présentent bien une surface d'émission de lumière qu'il a été choisi ici volontairement de ne pas représenter.It should also be noted that the optical elements are illustrated in the figures in a simplified manner with perfect matching of the focal points and optical axes for the sake of clarity of presentation. Such matches are not to be interpreted strictly, since in practice there may be slight deviations due to the imperfect nature of certain elements, mounting tolerance and / or to correct some effects related to imperfection of certain optical elements. The same applies to the light sources which are represented in a specific way, whereas it is clear that in practice these light sources are not perfectly punctual and have a light emission surface that has been chosen here. voluntarily not to represent.
A la
Il est à noter que la tranche 26 de la lame peut assurer la fonction de plieuse sans la présence de revêtement réfléchissant, et ce par l'utilisation du principe de réflexion totale sur un dioptre formé par l'interface entre deux milieux d'indice de réfraction différents. Dans ce cas, il conviendra de veiller à ce que les rayons rencontrent le dioptre formé par la tranche avec un angle d'incidence supérieur à l'angle limite de réflexion totale.It should be noted that the
Le module comprend également un premier réflecteur 10 dans le demi-espace inférieur. Il est représenté schématiquement par sa surface réfléchissante. Cette surface présente dans cet exemple un profil approximatif d'ellipsoïde, par exemple symétrique en rotation autour de son axe optique 20. Elle comprend un premier foyer 22 destiné à recevoir une source lumineuse et un second foyer confondu avec le foyer 24 de la lentille 4. L'axe optique 20 du premier réflecteur forme un angle avec l'axe optique 2 qui est compris entre 30° et 60°, préférentiellement compris entre 40° et 50°. La source lumineuse éclaire majoritairement dans un demi-espace délimité par le plan transversal comprenant l'axe optique 20 du réflecteur et est préférentiellement du type à diode électroluminescente.The module also comprises a
Le module comprend également un deuxième réflecteur 8 représenté par sa surface réfléchissante. Elle est composée de deux sous-surfaces réfléchissantes de profil elliptique symétrique en révolution par rapport aux axes optiques 12 et 14 respectifs. Chaque sous-surface réfléchissante comporte un premier foyer 16 ou 18 destiné à recevoir une source lumineuse et un second foyer confondu avec le foyer 24 de la lentille et le second foyer du premier réflecteur. La surface réfléchissante du deuxième réflecteur 8 est constituée de la juxtaposition des deux sous-surfaces dans un demi-espace délimité par un plan passant par les axes optiques respectifs 12 et 14 et l'axe optique 2 de la lentille 4, de manière à former une cavité doublement concave apte à réfléchir les rayons lumineux provenant des premiers foyers 16 et 18 vers le second foyer 24. Les deux axes optiques respectifs 12 et 14 forment un angle aigu entre eux et forment, chacun, un angle égal avec l'axe optique 2 de la lentille et du module.The module also comprises a
Le module d'éclairage comprend également une plaque 9 réfléchissante sur ses deux faces et disposée approximativement dans le plan passant par les axes optiques 12 et 14 du deuxième réflecteur et la tranche réfléchissante 26 de la lame 6. Elle est disposée de manière adjacente ou quasi-adjacente au bord arrière de la tranche et s'étend jusqu'à une distance depuis ce bord arrière. Le bord arrière de la plaque 9 arrive approximativement à hauteur de l'intersection de la surface réfléchissante du premier réflecteur 10 avec ledit plan. Plus précisément, le profil du bord arrière de la plaque réfléchissante 9 est en forme de V dont la pointe est alignée avec l'axe optique et de symétrie 2 du module et dirigée vers l'arrière, de manière à ce que la surface réfléchissante de la plaque couvre une majeure partie de la zone délimitée par l'intersection de la surface réfléchissante du premier réflecteur avec le plan. La plaque réfléchissante 9 joue le rôle de plieuse complémentaire et sera explicité plus loin.The lighting module also comprises a
Il est à noter que les axes optiques 12 et 14 des sous-surfaces réfléchissantes du deuxième réflecteur 8 ne doivent pas nécessairement être compris dans le plan médian horizontal. En effet, ils peuvent former un certain angle avec ce plan.It should be noted that the
Une vue en coupe et de principe optique du dispositif de la
Le deuxième réflecteur 8 génère avec sa ou ses sources lumineuses 16 et 18 un faisceau à coupure assurant par exemple une fonction d'éclairage de type « code ». En effet, la majorité des rayons émis par la source lumineuse sont réfléchis par la surface réfléchissante du deuxième réflecteur 8 vers le second foyer 24 et sont transmis par la lentille en un faisceau de rayons essentiellement parallèles. Un tel rayon est illustré par un trait plein depuis la source lumineuse 16, 18 jusqu'à la lentille en passant par la surface réfléchissante et le second foyer 24. Certains rayons, notamment ceux émis depuis une zone latérale avant de la source lumineuse, rencontrent la plieuse 26 à l'arrière du foyer 24. Ils sont réfléchis ou « repliés » vers une partie haute de la lentille avec un angle d'incidence tel qu'ils sortent de la lentille inclinés légèrement vers le bas. Un tel rayon est illustré par un trait interrompu à la partie supérieure de la figure. La plieuse joue donc le rôle d'un cache dans un système de projection classique et la projection de son bord forme la coupure horizontale du faisceau projeté, cette coupure étant utile notamment pour une fonction d'éclairage du type « code ». Il est à noter que comme mentionné précédemment, la plieuse comporte un ressaut au niveau du bord avant dit bord de coupure de manière à ce que la coupure soit plus haute d'un côté que de l'autre du plan médian vertical afin de projeter un faisceau du type « code » en conformité avec la législation.The
La plupart des rayons émis par la source lumineuse 22 du premier réflecteur 10 sont réfléchis par la surface réfléchissante du réflecteur, traversent la lame 6, passent par le foyer 24, sont projetés par la partie haute de la lentille 4 et viennent s'ajouter au faisceau provenant du réflecteur supérieur afin d'assurer la fonction « route ». Un tel rayon est illustré par un train interrompu à la partie inférieure de la figure.Most of the rays emitted by the
La
La tranche supérieure de la lame formant la plieuse est inclinée depuis le bord de coupure vers le bas du module afin de concentrer d'avantage les rayons réfléchis par la plieuse. La
Il est à noter que le matériau de la lame sera préférentiellement du verre par opposition aux matériaux plastiques pour des raisons de tenue en température. En effet, la présence de la lentille a pour effet que les rayons solaires extérieurs peuvent se concentrer via la lentille au foyer 24 et surchauffer le matériau de la lame. La tranche de la lame opposée à la tranche servant de plieuse peut également être similairement incliné, et ce de manière symétrique de manière à réduire la hauteur de la face arrière d'une valeur donnée. Bien que cette tranche de la lame ne joue aucun rôle du point de vue de l'optique, une telle inclinaison ou angle de dépouille permet de simplifier la mise à forme de la lame en simplifiant le démoulage selon une direction perpendiculaire aux faces avant et arrière. Les faces optiques peuvent ensuite être surfacée afin d'en garantir la planéité et les qualités optiques.It should be noted that the material of the blade will preferably be glass as opposed to plastic materials for reasons of temperature resistance. Indeed, the presence of the lens has the effect that the external sunlight can concentrate via the lens at the
La surface réfléchissante du premier réflecteur est corrigée afin de compenser la première réfraction à laquelle les rayons sont soumis lors de leur entrée dans la lame. Le calcul de correction de la surface va être décrit ci-après en relation avec la
Le calcul se base sur l'application du principe de Huygens et le principe de Fermat relatif au chemin optique.The calculation is based on the application of the Huygens principle and Fermat's optical path principle.
En effet, selon le principe de Huygens, la lumière se propage de proche en proche, l'ensemble des points d'égale perturbation lumineuse étant appelée surface d'onde. Chacun des points de cette surface atteint par la lumière se comporte comme une source secondaire qui émet des ondelettes sphériques dans un milieu isotrope. La surface enveloppe de ces ondelettes forme une nouvelle surface d'onde.Indeed, according to the principle of Huygens, the light spreads from one to the next, the set of points of equal light disturbance being called the wave surface. Each point of this surface reached by light behaves like a secondary source that emits spherical wavelets in an isotropic medium. The envelope surface of these wavelets forms a new wave surface.
La lumière se propage plus difficilement ou plus lentement dans les milieux autres que le vide. L'indice n du milieu est défini par
où c et v sont la vitesse de la lumière dans le vide et dans le milieu, respectivement.Light propagates more difficultly or more slowly in environments other than vacuum. The middle index n is defined by
where c and v are the speed of light in the vacuum and in the medium, respectively.
Le chemin optique est le chemin parcouru par la lumière parcouru dans le vide durant la durée de propagation dans le milieu :
où s désigne l'abscisse curviligne le long du chemin parcouru dans le milieu entre les points A et B, et AB la longueur du chemin parcouru entre A et B. Le principe de Fermat s'énonce : entre deux points A et B, atteints par la lumière, le chemin optique suivi le long du trajet est stationnaire. Il résulte notamment
en considérant que ds'=-ds est l'élément de coordonnée curviligne de B vers A, on peut alors écrire que
where s denotes the curvilinear abscissa along the path traveled in the middle between points A and B, and AB the length of the path traveled between A and B. The Fermat principle is stated: between two points A and B, reached by the light, the optical path followed along the path is stationary. It results in particular
considering that ds' = - ds is the curvilinear coordinate element from B to A, we can then write that
C'est le principe de retour inverse de la lumière : le trajet suivi par la lumière pour aller d'un point un autre ne dépend pas du sens de propagation de la lumière.This is the reverse principle of light: the path followed by the light to go from one point to another does not depend on the direction of propagation of light.
Le chemin optique inverse depuis un point d'émergence O correspondant au foyer 24 jusqu'à la source lumineuse F se calcule comme suit :
- Un référentiel x-y-z centré en O est illustré à la figure. Un vecteur
r de longueur égale à 1, originaire du point O et orienté selon le chemin inverse de la lumière dans la lame depuis le point O où ϕ est le complément de l'angle avec l'axe z et θ le complément de l'ange avec l'axe y et s'écrit :
- An xyz repository centered at O is shown in the figure. A vector
r of length equal to 1, originating from the point O and oriented along the inverse path of the light in the plate from the point O where φ is the complement of the angle with the axis z and θ the complement of the angel with the axis y and is written:
La première section de chemin optique OP s'écrit :
où ε est l'épaisseur de la lame.The first optical path section OP is written:
where ε is the thickness of the blade.
Il s'ensuit :
Or, en l'application de la loi de Snell-Descartes seul l'angle ϕ change au passage du dioptre, si bien que n ·
et
d'où on peut calculer
où K qui est le chemin optique de O à F est une constante en application du principe de Fermat. Il s'ensuit
and
from where we can calculate
where K, which is the optical path from O to F, is a constant in application of the Fermat principle. It follows
Le vecteur
En d'autres termes plus physiques, le réflecteur est corrigé de manière à transformer une surface d'onde sphérique issue d'un point source F à la surface de l'émetteur en une surface d'onde sphérique dans la matière de la lame, ayant pour centre le deuxième foyer 24, ce deuxième foyer étant situé dans la matière de la lame au voisinage de sa face de sortie avant et de sa face supérieure (tranche).In other words more physical, the reflector is corrected so as to transform a spherical wave surface from a source point F to the surface of the emitter into a spherical wave surface in the material of the blade, centering the
La correction de surface réfléchissante elliptique est applicable à diverses configurations, notamment la configuration du réflecteur 10 de la présente invention, ainsi qu'à une configuration classique telle qu'illustrée en trait interrompu 42 à la
Il à noter que la correction ne doit pas nécessairement être faite sur toute la surface réfléchissante mais bien essentiellement sur la zone réfléchissant les rayons qui vont former la partie centrale du faisceau.It should be noted that the correction does not necessarily have to be made on the entire reflective surface but essentially on the area reflecting the rays that will form the central part of the beam.
La
La
Il est à noter que le fait de prévoir un angle de dépouille à la tranche de la lame formant la plieuse et tel que décrit précédemment en relation avec la
Claims (14)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1055851A FR2962785B1 (en) | 2010-07-19 | 2010-07-19 | PLYWOOD ON TRANSPARENT BLADE WITH FILE |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2410238A1 true EP2410238A1 (en) | 2012-01-25 |
EP2410238B1 EP2410238B1 (en) | 2014-11-19 |
Family
ID=43568089
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP11174428.0A Active EP2410238B1 (en) | 2010-07-19 | 2011-07-18 | Optical reflector consisting of a transparent blade with an undercut |
Country Status (2)
Country | Link |
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EP (1) | EP2410238B1 (en) |
FR (1) | FR2962785B1 (en) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1260758A1 (en) * | 2001-05-25 | 2002-11-27 | Valeo Vision | Headlight for motor vehicle |
EP1357334A1 (en) | 2002-04-25 | 2003-10-29 | Valeo Vision | Elliptical lighting module without screen providing a cut-off beam and headlamp comprising the same |
EP1666787A1 (en) * | 2004-12-06 | 2006-06-07 | Valeo Vision | Lighting module for vehicle headlamp |
US20070147062A1 (en) * | 2005-12-28 | 2007-06-28 | Koito Manufacturing Co., Ltd. | Vehicle headlamp |
FR2917484A1 (en) | 2007-06-18 | 2008-12-19 | Valeo Vision Sa | OPTICAL MODULE FOR AUTOMOTIVE LIGHTING DEVICE |
EP2302292A1 (en) * | 2009-09-29 | 2011-03-30 | Valeo Vision | Optical module with folder formed by a transparent material/air dioptre |
-
2010
- 2010-07-19 FR FR1055851A patent/FR2962785B1/en not_active Expired - Fee Related
-
2011
- 2011-07-18 EP EP11174428.0A patent/EP2410238B1/en active Active
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1260758A1 (en) * | 2001-05-25 | 2002-11-27 | Valeo Vision | Headlight for motor vehicle |
EP1357334A1 (en) | 2002-04-25 | 2003-10-29 | Valeo Vision | Elliptical lighting module without screen providing a cut-off beam and headlamp comprising the same |
EP1666787A1 (en) * | 2004-12-06 | 2006-06-07 | Valeo Vision | Lighting module for vehicle headlamp |
US20070147062A1 (en) * | 2005-12-28 | 2007-06-28 | Koito Manufacturing Co., Ltd. | Vehicle headlamp |
FR2917484A1 (en) | 2007-06-18 | 2008-12-19 | Valeo Vision Sa | OPTICAL MODULE FOR AUTOMOTIVE LIGHTING DEVICE |
EP2302292A1 (en) * | 2009-09-29 | 2011-03-30 | Valeo Vision | Optical module with folder formed by a transparent material/air dioptre |
Also Published As
Publication number | Publication date |
---|---|
FR2962785B1 (en) | 2014-11-21 |
EP2410238B1 (en) | 2014-11-19 |
FR2962785A1 (en) | 2012-01-20 |
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