GB1571960A - Headlights - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO HEADLIGHTS (71) We, CIBIE PROJECTEURS, a société Anonyme organised under the laws of France, 17 Rue Henri-Gautier, 93012 Bobigny, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement-: The present invention relates to a novel headlight structure providing both a low beam and a full beam. The term 'low beam' is used herein to embrace both dipped headlight beams, which have an asymmetrical top cut-off, and fog-lamp type beams, which have a substantially horizontal top cut-off. The full beam is also sometimes known as the far beam.

The optimal characteristics which a light beam must possess have been known for a long time, for full beam headlights (long range beam), for fog lamps (beam with short range upwardly limited by a substantially horizontal plane of cut, the beam moreover being spread out laterally and not comprising any upwardly directed ray which may produce undesirable phenomena with the droplets of fog) and for dipped headlights (asymmetrical cut - no dazzling rays).

Headlight structures have already been proposed having a plurality of mirrors for fulfilling several lighting functions. The applicants have marketed, under the name 'BIODE', a dipped-beam/far-beam headlight comprising a main parabolic reflector for the dipped beam cooperating with a filament placed slightly in front of its focus to form a slightly convergent dipped beam, and a second parabolic reflector producing the far-beam, this second reflector being disposed inside the main reflector in the lower part thereof. In such a headlight, a screen or like means cooperates with the filament of the main reflector to define the asymmetrical cut of the corresponding dipped beam. Figure 1 of the accompanying drawings schematically shows such a known, complex structure with two reflectors.Reference Rl designates the main parabolic reflector with focus F, and filament f1 cooperating with a screen Cl.

Reference R2 designates the second parabolic reflector of focus F2, of filament f2 and axis A2. The dipped beam is constituted, as shown, by the light rays issuing from f l, not intercepted by screen C1, and returned in convergent manner by the upper useful zone of the reflector R,. The asymmetrical cut of the dipped beam thus returned by Rl, is determined by the edges of the screen Cl. For its part, the reflector R2 produces a far-beam. A glass G common to both reflectors closes the headlight.

Such a construction is compact and advantageous. It should be noted that the reflector R2, placed below the axis A1 of the reflector R1, does not form a screen for the rays rturned by Rl since the screen C prohibits the formation of light rays issuing from f1 which would strike the lower part of Rl, be reflected by Rl and finally intercepted by R2. (Such a theoretical ray is shown in broken lines in Figure 1).

In other words, the two interfitting mirrors such as Rl and R2 have virtually no relative role, i.e. the presence of one is essentially without influence on the useful light beam issuing from the other.

In view of the conventional solution described above with reference to Figure 1, concerning dipped-beam /far-beam headlights, and the differences between a dipped beam and a fog lamp beam, the man skilled in the art can fairly easily produce a fog-lamp/far-beam headlight from the dipped-beam/far-beam headlight of Figure 1. This would involve the following adaptations: a) modification of the screen Cl so that the cut of the beam becomes a symmetrical horizontal cut; b) disposition in front of the filament f, and thereabove of a screen adapted to intercept the upwardly directed light rays Rmd issuing from the filament and passing directly through the front glass; c) modification of the front glass to obtain a spread out beam.

The present invention proposes a lowbeam/full-beam headlight structure with two interfitting reflectors, which does not follow the teaching of the prior art.

According to one aspect of the present invention, a low-beam/full-beam headlight for an automobile comprises a main reflector and a second reflector disposed inside the main reflector, in which headlight the axes of the reflectors are substantially parallel, the main reflector cooperates with a light source which is associated therewith so as to reflect a slightly divergent beam, the inner reflector extends over the whole width of the main reflector, and is located above the axial horizontal plane of the main reflector, so as to intercept the upwardly directed rays returned by the main reflector or directly emitted by the light source associated therewith, and the lower edge of the inner reflector determines the cut-off of the beam returned by the main reflector.

The structure according to the invention is remarkably simple and efficient, since it does not comprise any screen. The inner reflector itself serves to define the beam of the main reflector.

The invention is particularly but not exclusively applicable to headlights in which the main reflector acts as a fog lamp while the inner reflector produces a far beam.

According to another aspect of the present invention, a headlight for a motor vehicle comprises: a main reflector; a second reflector disposed inside the main reflector with its optical axis parallel to that of the main reflector; a main light source positioned near the focus of the main reflector, to produce a slightly reflected beam; and a second light source positioned near the focus of the second reflector; the inner reflector extending over a substantial part of the width of the main reflector, and being situated mainly above the horizontal plane through the focus of the main reflector, to intercept mostly upwardly directed rays from the main light source or from the main reflector, with the lower edge of the second reflector defining the cut-off of the beam from the main reflector.

The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: Figure 1 has already been discussed.

Figure 2 is a schematic view in axial section of the headlight according to the invention Figures 3a and 3b show two isolux diagrams illustrating the optical properties of the system of Figure 2.

Referring now to the drawings, Figure 2 shows a headlight according to the invention, comprising a main reflector 100 and an inner reflector 200. The optical axis 101-101 and 201-201 of the reflectors 100 and 200 are parallel.

On axis 101-101 is located a filament 102 which is disposed slightly behind the focus 103 of mirror 100. In this way, the light beam issuing from 102 and returned by reflector 100 is, as shown, slightly divergent.

The two reflectors 100 and 200 are reflecting parabolic surfaces cut and limited by horizontal planes. The reflector 100 is completed by flat sides 100a and 100b and is closed by a glass G.

The reflector 200 serves to produce a long-range headlight beam in a manner known per se, its filament 202 being substantially centred on its focus 203.

In combination with the formation of a divergent beam by the reflector 100, the following arrangements are made according to the invention: - the inner reflector 200 extends over the whole width of the main reflector 100, in the upper part thereof, just above the horizontal plane passing through axis 101-101. Consequently, all the upwardly directed light rays are intercepted, whether they be reflected ones, such as Rmr, or direct such as Rd; - furthermore, the lower edge 205 of the inner reflector 200 is disposed near the central horizontal plane passing through the axis 101-101, so that this edge 205 determines the cut of the beam reflected by the main reflector 100 along a horizontal plane of cut, in accordance with the requirements of a fog-lamp beam.

The reflector 200 therefore cooperates in two ways in the formation of the fog-lamp beam returned by the main reflector 100: its rear surface intercepts upwardly directed rays, whilst its lower edge determines a very clear cut of the beam.

Figures 3a and 3b illustrate the effects obtained. They show isolux curves obtained on a screen arranged 25 metres away from the headlight, of the conventional test type. Point H corresponds to the vanishing point of the road to be illuminated. The numerical values represented are lux values.

Figure 3a shows the isolux curves of the beam returned by the reflector 100 in the absence of reflector 200.

Figure 3b shows the transformation of this same beam when the reflector 200 has been placed in position. The upwardly directed rays have disappeared, the beam is spread out laterally, and a clear pseudohorizontal cut has appeared.

The invention is, of course, not limited to the embodiment which has been described but covers modifications which do not depart from the scope thereof.

In particular, it is applied to any form of headlight (round or rectangular). It is also applied to a dipped-/far-beam headlight and to this end, the edge 205 of the reflector 200 is cut asymmetrically (horizontal plane of cut on one side and inclined on the other).

WHAT WE CLAIM IS: 1. A low-beam/full-beam headlight for an automobile, comprising a main reflector and a second reflector disposed inside the main reflector, in which headlight the axes of the reflectors are substantially parallel, the main reflector cooperates with a light source which is associated therewith so as to reflect a slightly divergent beam, the inner reflector extends over the whole width of the main reflector, and is located above the axial horizontal plane of the main reflector, so as to intercept the upwardly directly rays returned by the main reflector or directly emitted by the light source associated therewith, and the lower edge of the inner reflector determines the cut-off of the beam returned by the main reflector.

2. A headlight as claimed in claim 1, wherein the main reflector cooperates with an axial light filament disposed behind its focus.

3. A headlight as claimed in either one of claims 1 and 2, wherein the lower edge of the inner reflector extends substantially in the horizontal axial plane of the main reflector, to form a cut, fog-lamp beam.

4. A headlight as claimed in one of claims 1 to 3, wherein the two reflectors are parabolic reflectors constituted by parabolic surfaces delimited by horizontal planes.

5. A headlight substantially as hereinbefore described and illustrated in the accompanying drawings.

6. A headlight for a motor vehicle, comprising: a main reflector; a second reflector disposed inside the main reflector with its optical axis parallel to that of the main reflector; a main light source positioned near the focus of the main reflector, to produce a slightly divergent reflected beam; and a second light source positioned near the focus of the second reflector; the inner reflector extending over a substantial part of the width of the main reflector, and being situated mainly above the horizontal plane through the focus of the main reflector, to intercept mostly upwardly directed rays from the main light source or from the main reflector, with the lower edge of the second reflector defining the cut-off of the beam from the main reflector.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. absence of reflector 200. Figure 3b shows the transformation of this same beam when the reflector 200 has been placed in position. The upwardly directed rays have disappeared, the beam is spread out laterally, and a clear pseudohorizontal cut has appeared. The invention is, of course, not limited to the embodiment which has been described but covers modifications which do not depart from the scope thereof. In particular, it is applied to any form of headlight (round or rectangular). It is also applied to a dipped-/far-beam headlight and to this end, the edge 205 of the reflector 200 is cut asymmetrically (horizontal plane of cut on one side and inclined on the other). WHAT WE CLAIM IS:

1. A low-beam/full-beam headlight for an automobile, comprising a main reflector and a second reflector disposed inside the main reflector, in which headlight the axes of the reflectors are substantially parallel, the main reflector cooperates with a light source which is associated therewith so as to reflect a slightly divergent beam, the inner reflector extends over the whole width of the main reflector, and is located above the axial horizontal plane of the main reflector, so as to intercept the upwardly directly rays returned by the main reflector or directly emitted by the light source associated therewith, and the lower edge of the inner reflector determines the cut-off of the beam returned by the main reflector.

2. A headlight as claimed in claim 1, wherein the main reflector cooperates with an axial light filament disposed behind its focus.

3. A headlight as claimed in either one of claims 1 and 2, wherein the lower edge of the inner reflector extends substantially in the horizontal axial plane of the main reflector, to form a cut, fog-lamp beam.

4. A headlight as claimed in one of claims 1 to 3, wherein the two reflectors are parabolic reflectors constituted by parabolic surfaces delimited by horizontal planes.

5. A headlight substantially as hereinbefore described and illustrated in the accompanying drawings.

6. A headlight for a motor vehicle, comprising: a main reflector; a second reflector disposed inside the main reflector with its optical axis parallel to that of the main reflector; a main light source positioned near the focus of the main reflector, to produce a slightly divergent reflected beam; and a second light source positioned near the focus of the second reflector; the inner reflector extending over a substantial part of the width of the main reflector, and being situated mainly above the horizontal plane through the focus of the main reflector, to intercept mostly upwardly directed rays from the main light source or from the main reflector, with the lower edge of the second reflector defining the cut-off of the beam from the main reflector.