Classifications

• • 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
  • F21S41/33—Multi-surface reflectors, e.g. reflectors with facets or reflectors with portions of different curvature
  • F21S41/334—Multi-surface reflectors, e.g. reflectors with facets or reflectors with portions of different curvature the reflector consisting of patch like sectors

Definitions

• the present invention relates generally to headlamps of the elliptical type for motor vehicles.
• a projector of this kind generally comprises a mirror having a first focus area in the vicinity of which is placed a light source and a second focus area in the vicinity of which the radiation of the source is concentrated after reflection by the mirror.
• a lens typically a convex plane spherical lens, is focused in the vicinity of the second focal area and projects this concentrated radiation onto the road.
• a satisfactory passing beam that is to say giving the maximum visual comfort to the driver while respecting the regulations in force, must include a spot of relatively sharp concentration either in the axis of the road, either slightly offset laterally down the aisle
• the mirror of the aforementioned type generally leads to a beam having a concentration zone of excessive width and as a corollary of insufficient light intensity.
• Another limitation of this known headlight is that the beam may have an insufficient thickness, that is to say have a high concentration of light just under the cut, but insufficiently illuminate the road closer to the vehicle.
• the beams generated by the headlamps of the aforementioned type generally have a relatively reduced thickness, and in any case difficult to control, whereas it is rather desirable to have, at least in the case of a passing beam, a beam which has a substantial thickness towards the sides, and which at the same time does not generate excess light in the center line of the vehicle and too close to it.
• the present invention aims to overcome these limitations of the state of the art and to provide a projector of the aforementioned type, in which the beam obtained is improved.
• Another object of the present invention is to give the designer great flexibility in obtaining different characteristics of the beam, such as width and intensity of the concentration spot, evolution of the intensity towards the lateral edges of the beam.
• the invention provides a motor vehicle headlamp, of the type capable of generating a light beam of given configuration and comprising a light source, a mirror of the elliptical type in the vicinity of a first focus of which the light source is located, a lens placed in front of the mirror, characterized in that the mirror comprises at least two zones situated side by side and capable of forming in a focal region of the ' lens light spots preformed in width, and in that the spots overlap each other in a direction horizontal.
• each zone of the mirror has a surface having a horizontal generator such that the rays which it reflects from the rays coming from the source extend in vertical planes which intersect an imaginary line at points whose curvilinear abscissas evolve on this line according to a predetermined law.
• said imaginary lines of the different zones are continuous.
• said imaginary lines of the different zones are curves.
• Each curve is all the more distant from the focal region of the lens, in a direction parallel to the axis of the mirror, that said curve is laterally distant from said axis.
• a vertical section of said mirror situated in a vertical plane containing the rays reflected by the horizontal generator is capable of concentrating said rays reflected on said associated point of the imaginary line, said imaginary line being a line of secondary focal points , and said points being secondary foci.
• an upper region of a vertical section is able to concentrate the rays which it reflects on another point situated between said associated secondary focal point and the lens.
• transition line is determined by the intersection of the surfaces of said zones, and said transition line is distinct from respective horizontal isodeviation lines of said zones.
• the mirror has two zones separated by a transition line extending substantially in the middle of the mirror in the horizontal direction.
• the mirror has three zones separated by two transition lines extending on either side of the axis of the mirror.
• a central area of the mirror is substantially narrower, in the horizontal direction, than two lateral areas.
• the projector further comprises a mask located in the focal region of said lens, so as to generate a cut beam.
• FIG. 1 illustrates by a partial schematic view in horizontal section the principle of construction of a zone of the mirror of a projector according to the invention
• FIG. 2 illustrates by a partial schematic view in vertical section a first method of construction of the vertical sections from the mirror
• FIG. 3 illustrates by a partial schematic view in vertical section a second mode of construction of the vertical sections of the mirror
• FIG. 4 is a partial schematic view in horizontal section of a projector according to a first concrete embodiment of the invention
• FIG. 7 is a partial schematic view in horizontal section of a projector according to a second embodiment of the invention.
• FIGS 8a to 8c illustrate by sets of isocandela curves the light distribution of the beam parts generated by three individual regions of the mirror of the projector of Figure 7, and Figure 9 illustrates by a set of isocandela curves the light distribution of the beam overall obtained.
• FIG. 1 there have been shown diagrammatically elements of a headlamp according to the invention, which comprises a light source 10, a mirror 20, a screen or masking mask 30 and a lens 40.
• the source 10 is typically the filament of an incandescent lamp or the arc of a discharge lamp.
• the mask 30 has, for example, in a conventional manner per se, an upper edge defined by two segments of lines defining together in an inverted and flattened "V", so as to generate a passing beam conforming to European regulations on the subject.
• the lens 40 is for example a planar / convex spherical lens, with a point focus, or even a toric lens.
• the mirror is constructed according to principles similar to those described in the document FR 2 704 044, to which reference will be made for more details, with differences with respect to these principles as will be explained below.
• the mirror consists of at least two zones constructed individually and connecting according to slightly angled transition lines generally extending from top to bottom.
• LFS line also makes it possible to control the focusing of the section of the mirror located in the vertical plane containing the reflected ray GF2.
• the line LFS can be any curve, preferably without discontinuity so as to avoid discontinuities in the generated surface.
• the whole of this section is able to focus the rays reflected by it on the point F2, the distance of which, measured along the axis xx, from the plane of the mask 30 can vary significantly along the LFS curve.
• each of these sections is therefore an elementary section of ellipsoid of revolution having foci FI and F2, and the parameters of this ellipsoid vary as the point F2 moves along the curve LFS. It is understood here that the profile of the aforementioned LFS curve makes it possible to control not only the width of the light spot which will be formed in the plane of the mask 30, but also the thickness of this light spot, this being all the more more important than the point F2 is distant in front of the mask 30.
• FIG. 3 illustrates an alternative embodiment of certain vertical sections of the mirror 20, according to which a part 20 ′ of the section illustrated in this figure exhibits the same behavior as in the case of FIG. 2, that is to say concentrates the radiation reflected on the point F2, while an upper part 20 '' of this section will concentrate the reflected radiation at a point F2 'distant from F2 towards the front, i.e. towards The lens.
• This also has the result of thickening at will the light spot in the plane of the mask 30, and therefore the thickness of the projected beam.
• the mirror 20 is then defined by designing a first zone characterized by a certain LFS curve and a certain rule for the evolution of the position. points F2 on this line as a function of the angle a of the rays emitted by the source, and at least a second zone characterized by another rule for changing the position of points F2, and if necessary by another line LFS whose trajectory is different from that which corresponds to the first zone.
• the rules for changing the positions of the points F2 between an area of the mirror and an adjacent area are such that there is an overlap, in the width direction, between the radiation produced in the plane of the mask 30 by an area and the radiation produced in this same plane by the adjacent area.
• This is achieved by designing the evolution rules for F2 points on the respective LFS lines of such that, for respective determined fractions of the first and second zones which are adjacent to the transition between the two zones, the horizontal angular intervals covered by the radiation reflected by these fractions of zones overlap. It is easily understood that, in this way, there will exist at the border between these two areas a slight bend, that is to say a non-differentiability, between the adjoining reflecting surfaces.
• F2 f ( ⁇ ) on these curves
• FIG. 4 schematically illustrates a first concrete embodiment of a mirror of a projector according to the invention, with two zones 20a and 20b designed as described above and which are separated by a transition edge 21 which extends noticeably in the middle of the mirror.
• FIGS. 5a and 5b illustrate the beam portions projected by the lens 40 from the light spots formed respectively by these two zones, and with the intervention of the mask 30. It is observed that the portion of the beam generated by the area 20a in combination with the mask 30 and the lens 40 (FIG. 5a) projects substantially to the right with respect to the central vertical axis of the projection screen and that, in the in the opposite direction, the part of the beam generated by the area 20b in combination with the mask 30 and the lens 40 (FIG. 5b) projects substantially to the left relative to the central vertical axis of the screen.
• FIG. 7 illustrates a second embodiment of a projector mirror according to the invention. This time it comprises " three zones, with two lateral zones 20a, 20b separated by a substantially narrower central zone.
• the parameters used when designing the individual surfaces are such that the two transition lines 21 and 22 between the adjacent zones do not correspond to horizontal isode-deflection lines, so that the three corresponding beam parts, as illustrated in FIGS. 8a, 8b and 8c respectively, have lateral edges with progressive fading of the light This results in a fusion of these beam parts to form a homogeneous overall beam, which has the same qualities as in the case of FIG. 6, with however a higher level of central concentration.
• a projector mirror according to the invention can be subdivided into as many zones as necessary, so as to be able to model the beam as a function of the objectives in terms of photometry both in regulatory terms and in terms of comfort plan visual.
• the invention applies to obtaining any type of beam, limited or not by a cut (the mask 30 being absent in the latter case).
• the invention is fundamentally different from the case where two light spots formed by two different zones of the same reflector, for example ellipsoidal, overlap by virtue of the fact that the light source is not punctual, but covers all cases where the overlap between these light spots goes beyond the overlap, which is, moreover, uncontrolled, which would be obtained with conventional surfaces.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=9521781

Family Applications (1)

Country Status (6)

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• 1998
  • 1998-01-09 FR FR9800339A patent/FR2773604B1/fr not_active Expired - Lifetime
• 1999
  • 1999-01-08 US US09/380,722 patent/US6431736B1/en not_active Expired - Fee Related
  • 1999-01-08 ES ES99900505.1T patent/ES2587134T3/es not_active Expired - Lifetime
  • 1999-01-08 WO PCT/FR1999/000020 patent/WO1999035438A1/fr active Application Filing
  • 1999-01-08 EP EP99900505.1A patent/EP0966633B1/de not_active Expired - Lifetime
  • 1999-01-08 JP JP53578099A patent/JP2001515649A/ja active Pending

Non-Patent Citations (1)

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