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(11) | EP 1 054 210 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Motor vehicle headlamp of the projection type |
| (57) A two-functional projecting headlamp with modes for a dipped and a long-distance
light beams comprised of a light source (1), an internal reflector (2), an external
reflector (3), an objective (4) an internal shade (51), external shades (61) and (62),
a frame (7), an electric part (8) and a moving mechanism (9), where in the dipped mode the internal shade (51) is projected on a road surface by means
of an objective (4) on a light background of said internal reflector (2) and produces
so a boundary between light and darkness and said external shades (61), (62) obstruct
the path of rays emitted by said source (1) in the direction to said external reflector
(3) and in the long-distance mode said switching mechanism (9) fixed to said frame
(7) moves all shades into such positions where none of said shades obstructs the path
of the outgoing light beam and on the road surface two light traces, the one produced
by the internal (2) and the one produced by external (3) reflectors, are added. |
[0001] The present invention relates to headlamps of projecting model for motor vehicles comprised of an internal and an external reflectors, a light source, a shade and an objective. The internal reflector is in the form of a free surface with one focus situated in proximity of the light source and the other focus situated in the space between the reflector and the objective. The external reflector takes also the form of a free surface but with one focus situated in proximity of the light source and the other focus situated off the headlamp optical system. In the headlamp, the method of integrating the dimmed and the long-distance beams is solved by means of changing shade positions what makes possible to change light beam geometry and intensity as a consequence of different concentration effects of the internal and the external reflectors.
Background of the Invention
[0002] The commercially used two-functional projecting systems that comprise of two models of reflectors, an internal one and an external one, an objective, a light source and shading elements and providing two basic headlamp modes, the long-distance and the dipped modes, exhibit generally the following design, structure and function of individual parts. The external and the internal reflectors form one assembly, i.e. a corpus, or at least the external reflector begins there where the internal one ends. A consequence of this is that the shading elements have only limited possibilities of movement during switching them between the long-distance and the dipped modes. Therefore, in case of both modes they have to be maintained within the optical system. The internal reflector is of an elliptical form and the external one is of a parabolic form both having one common focus in proximity of the light source. A disadvantage remains to be that by means of the reflectors with purely elliptical or parabolic reflecting surfaces it is very difficult or even impossible to obtain a satisfactory light distribution in front of an automobile.
[0003] A device providing switching between the long-distance and the dipped modes is mounted on the reflecting corpus, what is not preferable from the design point of view so far as the corpus is made of a thermoplastic material as undesired deformations could take place.
Summary of the Invention
[0004] The above mentioned disadvantages are removed by a projecting headlamp according to the present invention that is comprised of an independent internal and an external reflectors having the forms of free surfaces, an objective, a light source, an internal shade and two external shades. The internal reflector integrates light emitted by a light source and passing through a focus plane of said objective and further through said objective and the external reflector reflects light emitted by a light source into a direction which goes outside the objective. For the internal reflector the first focus is situated in proximity of the light source and the other focus is situated in proximity of the objective focus. The first focus of the external reflector is situated in proximity the light source and the other focus is situated off the optical system. A spiralled filament of a halogen lamp or an arc discharge can serve as a light source.
[0005] In the dipped mode, the internal shade, a part of which horizontal edge is situated in proximity of the horizontal line and the objective focus, is projected on the road surface by means of an objective on light background of the internal reflector and produces so a boundary between light and darkness, and the external shades obstruct rays emitted by the light source in the direction to the external reflector.
[0006] In the long-distance mode the switching device, which is mounted on the carrying frame, shifts all shades to such positions in which none of said shades obstructs the out shining light beam and on a road surface two light traces are added, i.e. the one produced by the internal and the one produced by the external reflectors. The internal reflector collimates the whole light beam and produces a light trace having no boundary between light and darkness and the external reflector shines into the area of maximum intensity of said light trace.
[0007] To improve homogeneity of the beam the external and the internal reflectors can be provided with a diffusion pattern. The objective can be of aspheric form to decrease optical aberrations.
Brief Description of the Drawings
[0008] An example of an embodiment of a headlamp according to this invention is shown in the attached drawings, where
Figure 1 is a cross-sectional illustration of a headlamp in plan view,
Figure 2 is a cross-sectional illustration of a headlamp along plane A-A,
Figure 3 is a cross-sectional illustration of a headlamp along plane B-B, and
Figure 4 is a schematic illustration of light beam traces distribution on a road surface.
Detailed Description
[0009] The Figures 1, 2 and 3 show an embodiment of a two-functional projector system which is comprised of a light source 1, an internal reflector 2, an external reflector 3, an objective 4 an internal shade 51, external shades 61 and 62, a frame 7, an electric part 8 and a moving mechanism 9. The internal reflector 2 is in the form of a free surface provided with a diffusion pattern to improve beam homogeneity and was made of a reflector 19 by cutting it in the positions of cutting curves 17 and 18. One focus F1 of this internal reflector 2 is situated in proximity of optical x-axis of the system and the other focus F2 is situated in the space between the internal reflector 2 and the objective 4. The external reflector 3 is separated from the internal reflector 2 and it takes the form of a free surface with one focus F1 common with that of the internal reflector 2 and the other focus is situated off the optical system. The light source 1 is situated in proximity of the focus F1. The light source 1 can be e.g. a spiralled filament of a bulb or an arc of a discharge lamp. For the dipped mode, an internal shade 51 is placed in vertical position in the space between the internal reflector 2 and the objective 4 so that a part of the horizontal edge of said shade 51 is situated in proximity of the focus F2 which focus F2 is simultaneously the focus of the objective 4. This objective 4 is situated in front of the whole optical system and it is of aspheric shape to decrease optical aberrations.
[0010] Obliquely to said optical x-axis of said headlamp the external shades 61 and 62 are placed and they are fixed to arms of the moving mechanism 9. The moving mechanism 9 is fixed to a carrying frame 7 situated on the bottom side of the headlamp and it is driven by the electric part 8.
[0011] For the dipped mode of the headlamp the rays emitted by the light source 1 are collimated by the internal reflector 2 into the space of the focus F2 of the objective 4 and this objective 4 projects the internal shade 51 on the light background of the reflector 2 on the road surface and produces so the light trace 12, see Fig. 4, which trace 12 is situated below the light and darkness boundary 15. Simultaneously, the external shades 61 and 62 obstruct path of rays emitted by the light source in the direction to the external reflector 3. To provide this function, arms of the moving mechanism 9 having external shades 61 and 62 fixed to them form an angle β from 10° to 180°.
[0012] In the long-distance headlamp mode the mechanism 9 provides switching of shade 51 into the position 52 and switching of shades 61 and 62 into the positions 63 and 64 so that none of the shades for this mode obstructs any of the light beams that produce a sum of the traces 12 and 13 produced by the reflector 2 and the trace 14 produced by the reflector 3 that is not collimated by objective 4 on the road surface. Whereas, the traces 12 and 13 exhibit a broad side diffusion, the trace 14 is concentrated into the area of the maximum light beam intensity. For this long-distance mode, the arms of the moving mechanism 9 having external shades 61 and 62 fixed on them, perform rotational movement around the axis of rotation 16 into the position where the opening of both arms of the moving mechanism 9 forms an angle γ from 30° to 360° and simultaneously the internal shade 51 rotates around the axis of rotation 11 by an angle α from 0° to 180° or it can perform any translational or rotational movements or a combination of said basic movements. Also, the external shades 61 and 62 can have each their own axis of rotation or they can perform any translational or rotational movements or a combination of such movements.
[0013] In case of a headlamp the D is smaller or equal to V, whereby, D is the diameter of the objective 4 and V is the maximum dimension of the external reflector 3.
[0014] The headlamp arrangement in accordance with this invention makes possible to improve distribution of the light traces 12, 13 and 14 thanks to the external 3 and the internal 2 reflectors having the shape of a free surface. Further, it is possible to increase homogeneity of the light beams by providing diffusion patterns on both reflectors and to transfer the weight of the moving mechanism 9 from the reflectors to the carrying frame 7. Last but not least, it allows a higher movement freedom of the external shades 61, 62 owing to separation of the external 3 and the internal 2 reflectors.
Industrial Use
1. A projecting headlamp for motor vehicles provided with modes for a long-distance and
a dipped beams, comprised of a light source (1), an internal reflector (2), an external
reflector (3), an objective (4) an internal shade (51), external shades (61) and (62),
a frame (7), an electric part (8) and a moving mechanism (9), characterised in that for the dipped mode said objective (4) projects said shade (51) on light background
of said internal reflector (2) on a road surface where it produces a light trace (12)
and shades (61) and (62) obstruct rays emitted by said source (1) in the direction
to said reflector (3), which reflector (3) is not connected with said reflector (2)
and for the long-distance mode said mechanism (9) fixed to said frame (7) provides
switching of said shade (51) into a position (52) and switching of said shades (61),
(62) into positions (63), (64) so that none of said shades for this long-distance
mode obstructs any of the light beam traces (12), (13) produced by said reflector
(2) and the light beam trace (14) produced by said reflector (3) which light beam
is not collimated by said objective (4) on a road surface.
2. A headlamp according to claim 1, characterised in that for the dipped mode of the headlamp a part of said internal shade (51) is horizontal
and is situated in proximity of the headlamp horizontal line and further in proximity
of the focus F2 of said objective (4),
3. A headlamp according to claim 1, characterised in that said shade (51) has an axis of rotation (11) and that the turning angle α between
the dipped and the long-distance modes is in the range from 0° to 180°.
4. A headlamp according to claim 1, characterised in that between the dipped and the long-distance mode positions said shade (51) can do any
movement, both a translational one and a rotational one, or a combination of both
movements.
5. A headlamp according to claim 1, characterised in that said shades (61), (62) have a common axis of rotation (16) and the angle β for the
dipped mode is in the range from 10° to 180° and the angle γ for the long-distance
mode is in the range from 30° to 360°.
6. A headlamp according to claim 1, characterised in that said shades (61), (62) have each their own axes of rotation or they perform a translational
movement or a movement composed of a rotation and a translation between the positions
for the dipped and the long-distance modes.
7. A headlamp according to claim 1, characterised in that the diameter D of said objective (4) is equal or smaller than the largest horizontal
dimension V of the external reflector (3).
8. A headlamp according to claim 1, characterised in that said reflector (2) is a free surface with one focus F1 in proximity of said source
(1) and the other focus F2 between said source (1) and said objective (4).
9. A headlamp according to claim 1 and 8, characterised in that said reflector (2) is provided with optically diffusing patterns to improve light
trace homogeneity.
10. A headlamp according to claim 1, characterised in that said reflector (3) which is in form of a free surface has one focus F1 in proximity
of said source (1) and the other focus off the headlamp system.
11. A headlamp according to claims 1 and 10, characterised in that said reflector (3) is provided with a diffusion pattern to improve beam homogeneity.
12. A headlamp according to claim 1, characterised in that said external reflector (3) is divided into two parts, the left one and the right
one or to a plurality of independent parts.
13. A headlamp according to claim 1, characterised in that said light source (1) can be a laterally or axially positioned spiralled filament
of a halogen bulb, whereby, said filament is situated in proximity of said focus F1.
14. A headlamp according to claim 1, characterised in that said light source (1) is a laterally or axially positioned arc discharge in gas,
whereby, said arc is situated in proximity of said focus F1.
15. A headlamp according to claim 1, characterised in that said objective (4) is of aspheric form to minimise optic aberrations.
16. A headlamp according to claim 1, characterised in that said outer reflector (3) takes the form of said reflector (19) in the whole space
around the axis X in an angle range from 0° to 360° or it is limited by any cutting
curves (17) and (18).
17. A headlamp according to claim 1, characterised in that the light beam of said trace (12) is concentrated below the light and darkness boundary
(15), the light beam of trace (13) is concentrated above the light and darkness boundary
(15) and the light beam trace (14) is concentrated into the region of the maximum
light beam intensity.