Optical element for a laser vehicle headlight

Abstract

The invention relates to an optical element (1) for a laser vehicle headlight (2), wherein the laser vehicle headlight (2) comprises at least one laser light source (3) and at least one luminous element (4) which can be irradiated by the laser light source (3) and can thus be excited to emit visible light, wherein the optical element (1) has at least one receptacle for the luminous element (4) and at least one reflection layer (9) which reflects light in the direction of the laser light source (3) is assigned to the optical element (1) at least on a side of the luminous element (4) which faces away from the laser light source (3) in the mounted state. The invention additionally relates to a light source module (16) comprising at least one optical element (1) of this type, and a vehicle headlight (2) comprising at least one optical element (1) of this type or comprising at least one light source module (16) as mentioned initially.

Claims

1. An optical element (1) for a laser vehicle headlight (2), wherein the laser vehicle headlight (2) comprises at least one laser light source (3) and at least one luminous element (4) which is configured to be irradiated by the laser light source (3) and thus excited to emit visible light, the optical element (1) comprising: at least one receptacle for the luminous element (4); and at least one reflection layer (9) which reflects light in the direction of the laser light source (3), wherein the at least one reflection layer (9) is assigned to the optical element (1) at least on a side of the luminous element (4) which faces away from the laser light source (3) in a mounted state, wherein (i) the optical element (1) is formed as a solid body made of a substantially transparent, light guiding material, and the reflection layer (9) is arranged on a first side (5) of the optical element (1) facing away from the laser light source (3) in the mounted state, or (ii) the optical element (1) is formed as a hollow body made of a substantially transparent, light guiding material and is formed on a side of a rear wall (22) facing away from the laser light source (3) in the mounted state, the reflection layer (9) being arranged either on an inner side of the rear wall (22) facing the luminous element (4) or on an outer side of the rear wall (22) facing away from the luminous element (4), and wherein the first side (5) facing away from the laser light source (3) is formed as a free-form face having at least one focal point, and the receptacle for receiving the at least one luminous element is arranged in a focal point of the reflection layer (9).

2. The optical element (1) according to claim 1, wherein the optical element has a reflector element (10) applied to the first side (5) of the optical element (1) facing away from the laser light source (3) in the mounted state, wherein the reflection layer (9) is arranged on a side of the reflector element (10) facing the luminous element (4) or on a side of the reflector element (10) facing away from the luminous element (4).

3. The optical element (1) according to claim 2, wherein the first side (5) of the optical element facing away from the laser light source (3) and/or the side of the reflector element (10) facing the luminous element (4) and/or the side of the reflector element (10) facing away from the luminous element (4) is/are formed as a free-form face having at least one focal point.

4. The optical element according to claim 3, wherein the luminous element is arranged in a focal point.

5. The optical element according to claim 2, wherein the reflector element is made of a light-impermeable material.

6. The optical element according to claim 5, wherein the reflector element is applied in a form fitting manner to the first side.

7. The optical element (1) according to claim 1, wherein at least one light-impermeable absorption layer (6) is applied to the first side (5) of the optical element (1) facing away from the laser light source (3) in the mounted state.

8. The optical element according to claim 7, wherein the at least one light-impermeable absorption layer is applied to a reflection layer provided on the first side of the optical element.

9. The optical element (1) according to claim 1, wherein the at least one receptacle for the luminous element (4) is formed as a blind bore (7) or as a cavity (8) surrounded on all sides by the optical element (1).

10. The optical element (1) according to claim 1, wherein a second side (11) of the optical element (1) facing the laser light source (3) in the mounted state is formed as a flat delimitation face (21).

11. The optical element (1) according to claim 10, wherein a connection region (13) is provided in a manner adjoining the delimitation face (21) and connects the second side (11) of the optical element (1) to the first side (5) of the optical element (1).

12. The optical element (1) according to claim 11, wherein the connection region (13) is formed in a manner convergent from the second side (11) of the optical element (1) in the direction of the first side (5) of the optical element (1).

13. The optical element (1) according to claim 10, wherein the delimitation face (21) is substantially circular and the first side (5) of the optical element (1) likewise has a substantially circular cross section, wherein the diameter (14) of the first side (5) is greater than the diameter (15) of the delimitation face (21).

14. The optical element according to claim 10, wherein the delamination face runs substantially normal to the radiation direction of the laser light source.

15. The optical element (1) according to claim 1, wherein a second side (11) of the optical element (1) facing the laser light source (3) in the mounted state is covered at least in part by a light-impermeable screen device (12).

16. The optical element (1) according to claim 15, wherein the light-impermeable screen device (12) is formed as a light-impermeable coating.

17. The optical element according to claim 15, wherein the light-impermeable screen device covers the second side in a region below a horizontal plane running through the luminous element.

18. A light source module (16) for a laser vehicle headlight (2), wherein the laser vehicle headlight (2) comprises at least one laser light source (3) and at least one luminous element (4) which is configured to be irradiated by the laser light source (3) and thus excited to emit visible light, the light source module (16) comprising: an optical element (1) comprising: at least one receptacle for the luminous element (4); and at least one reflection layer (9) which reflects light in the direction of the laser light source (3), wherein the at least one reflection layer (9) is assigned to the optical element (1) at least on a side of the luminous element (4) which faces away from the laser light source (3) in a mounted state, wherein (i) the optical element (1) is formed as a solid body made of a substantially transparent, light guiding material, and the reflection layer (9) is arranged on a first side (5) of the optical element (1) facing away from the laser light source (3) in the mounted state, or (ii) the optical element (1) is formed as a hollow body made of a substantially transparent, light guiding material and is formed on a side of a rear wall (22) facing away from the laser light source (3) in the mounted state, the reflection layer (9) being arranged either on an inner side of the rear wall (22) facing the luminous element (4) or on an outer side of the rear wall (22) facing away from the luminous element (4), wherein the first side (5) facing away from the laser light source (3) is formed as a free-form face having at least one focal point, and the receptacle for receiving the at least one luminous element is arranged in a focal point of the reflection layer (9), and wherein the luminous element (4) is arranged in the optical element (1).

19. A vehicle headlight (2) which comprises the at least one light source module (16) according to claim 18.

20. A vehicle headlight, (2) comprising: at least one laser light source (3); at least one luminous element (4) which is configured to be irradiated by the laser light source (3) and thus excited to emit visible light; and an optical element (1) comprising: at least one receptacle for the luminous element (4); and at least one reflection layer (9) which reflects light in the direction of the laser light source (3), wherein the at least one reflection layer (9) is assigned to the optical element (1) at least on a side of the luminous element (4) which faces away from the laser light source (3) in a mounted state, wherein (i) the optical element (1) is formed as a solid body made of a substantially transparent, light guiding material, and the reflection layer (9) is arranged on a first side (5) of the optical element (1) facing away from the laser light source (3) in the mounted state, or (ii) the optical element (1) is formed as a hollow body made of a substantially transparent, light guiding material and is formed on a side of a rear wall (22) facing away from the laser light source (3) in the mounted state, the reflection layer (9) being arranged either on an inner side of the rear wall (22) facing the luminous element (4) or on an outer side of the rear wall (22) facing away from the luminous element (4), wherein the first side (5) facing away from the laser light source (3) is formed as a free-form face having at least one focal point, and the receptacle for receiving the at least one luminous element is arranged in a focal point of the reflection layer (9), and wherein the luminous element (4) is arranged in the optical element (1).

21. The vehicle headlight (2) according to claim 20, wherein the vehicle headlight (2) has at least one reflector (20) and the optical element (1) is arranged in the vehicle headlight (2) in such a way that the luminous element (4) is positioned in a focal point or in the vicinity of the focal point of the reflector (20).

Description

(1) The invention will be explained in greater detail hereinafter on the basis of a non-limiting exemplary embodiment, which is illustrated in the drawing, in which:

(2) FIG. 1 schematically shows a first variant of an optical element according to the invention;

(3) FIG. 2 schematically shows a second variant of an optical element according to the invention;

(4) FIG. 3 schematically shows a third variant of an optical element according to the invention;

(5) FIG. 4 schematically shows a fourth variant of an optical element according to the invention;

(6) FIG. 5 schematically shows a light source module with an optical element according to the invention; and

(7) FIG. 6 schematically shows a vehicle headlight with a light source module according to FIG. 5.

(8) For reasons of clarity, like elements in the figures are in each case provided with like reference signs.

(9) FIG. 1 shows a cross-sectional view of a first variant of an optical element 1 for use in a light source module 16 (see FIG. 5) or a laser vehicle headlight 2 (see FIG. 6). The optical element 1 is formed in accordance with this first variant as a solid body made of a transparent, light guiding material, for example glass or plastic.

(10) The optical element 1 has a receptacle, formed as a blind bore 7, for a luminous element 4. The luminous element 4 in this case is a phosphor converter of known type, which is excited by the radiation of monochromatic laser light to emit polychromatic, preferably white light. The luminous element 4 is spherical in the illustrated exemplary embodiment, but can also assume another form (for example ellipsoid form) depending on the field of application of the optical element 1. FIG. 1 additionally illustrates a laser light source 3, which irradiates the luminous element 4 with laser light. The radiation direction 200 is also shown.

(11) A reflection layer 9 is arranged on a first side 5 of the optical element, which faces away from the laser light source 3. The reflection layer 9 is formed here so as to be impermeable both for laser light and for the light emitted by the luminous element 4 and reflects radiated light in the direction of the laser light source 3. The reflection layer 9 can be formed for example by vapour deposition, painting or application of a separate reflection element. The thickness and/or degree of reflection of the reflection layer 9 is to be selected depending on the material used such that both laser light and light emitted by the luminous element 4 is properly reflected and is prevented from penetrating through the reflection layer 9. The reflection layer 9 is necessary since total reflection might not be provided due to the angle at which light radiated by the luminous element impinges.

(12) The visible light emitted by the luminous element 4 along the radiation direction 200 of the laser light source 3 can be utilised photometrically by the reflection layer 9, for example by being guided in the direction of the reflector 20 of a vehicle headlight 2 (see FIG. 6). Accordingly, beam paths that start from the luminous element 4 and are reflected by the reflection layer 9 into the vicinity of the luminous element 4 are illustrated in FIG. 1, whereby a “virtual” enlargement of the light source constituted by the luminous element 4 is produced.

(13) In addition, a further, light-impermeable absorption layer 6 is applied to the reflection layer 9 for safety reasons and absorbs both visible light and non-visible laser light. A layer of this type prevents light from exiting through the reflection layer 9—this may be advantageous when, for example, the reflection layer 9 is produced by vapour deposition: In this case, the layer is only a few micrometers thick and may be too thin in regions (or completely, where possible) or may be incomplete. The additional absorption layer 6 is therefore applied for example as a layer of paint or as a screen.

(14) Depending on the embodiment of the first side 5 of the optical element 1 in combination with the reflection layer 9, various light functions can be provided. For example, the first side 5 of the optical element 1 (that is to say the outer face) can be formed in such a way that it has at least one focal point and the receptacle formed as a blind bore 7 is arranged such that the luminous element 4, when introduced into the receptacle, comes to lie in one of these focal points. To this end, the first side 5 (and therefore also the reflection layer 9) is preferably formed as a free-form face. The embodiment of a free-form face is known to a person skilled in the art.

(15) In a variant, the first side 5 and therefore the reflection layer 9 applied thereto is formed such that light above, below and to the side in the vicinity of the luminous element 4 is reflected and contributes to a virtual enlargement of the light source or of the luminous element 4—the luminous element 4 in this variant is virtually surrounded by a ring of reflected light. The reflection layer 8 thus conducts the light reflected thereby predominantly past the luminous element. This variant is illustrated in FIG. 1.

(16) The optical element 1 according to FIG. 1 corresponds slightly in terms of form to a sphere segment. The second side 11 of the optical element 1 facing the laser light source 3 in the mounted state is formed as a flat delimitation face 21 preferably running substantially normal to the radiation direction 200 of the laser light source 3. The first side 5 of the optical element facing away from the laser light source 3, as already mentioned, is formed as a free-form face with at least one focal point, wherein the luminous element 4 can preferably be arranged in a focal point. Said free-form face corresponds slightly to a spherical dome or a spherical cap, wherein, due to the reflection characteristics, it is discernible that it does not actually have such a form. In principle, a reverse design or arrangement is also possible, that is to say the delimitation face 21 is thus arranged in a manner facing away from the laser light source 3. The delimitation face 21 does not have to be formed as a flat face, but can also assume another form, for example it can be concave, convex or also formed with an undulating surface in order to additionally influence the beam path.

(17) FIG. 2 shows a variant of the optical element 1 according to the invention, in which a connection region 13 is provided between the delimitation face 21 and the first side 5 of the optical element. The connection region 13 connects the first side 5, which faces away from the laser light source 3 in the mounted state, to the delimitation face 21 on the second side 11 facing the laser light source 3. The connection region 13 can also be provided with a coating, for example with a light-impermeable, absorbing layer or also with a reflective layer, wherein the layer can act in a reflective manner either in the direction of the optical element interior or also outwardly. The connection region 13 and also the delimitation face 21 may be provided additionally with any surface structure that has light-collecting and/or light-scattering properties. In principle, the individual surface regions of the optical element 1 may thus be different, for example with light-impermeable and/or reflective coatings or surface structures that refract or influence the emerging light. These variants, however, are not illustrated in the figures.

(18) The connection region 13 is formed in the illustrated exemplary embodiment in a manner convergent in the direction of the laser light source 3. To this end, the delimitation face 21 is substantially circular for example, and the first side 5 of the optical element 1 also has a substantially circular cross section. Here, the cross section runs in a plane arranged normal to the radiation direction 200 of the laser light source 3—that is to say normal to the drawing plane and to the radiation direction 200 in the present figures. The first diameter 14 of the first side 5 is greater than the second diameter 15 of the delimitation face 21, and therefore the convergent form is provided. Of course, a reverse embodiment is also possible here.

(19) In a second variant of the invention, which is shown in FIG. 2 by dashed lines, the reflection layer 9 is applied to a reflector element 10, which is applied to the first side 5 of the optical element 1. The reflection layer 9 can be applied here on the side of the reflector element 10 facing the optical element 1. The reflector element 10 preferably consists of a light-impermeable or light-absorbing material, for example plastic or metal (for example sheet metal). Of course, the reflector element 10 can also be manufactured from a light-permeable material and the reflection layer 9 can be applied on the side facing away from the optical element 1. In this case, however, it would also be favourable to apply a light-impermeable layer to the reflection layer 9 in order to prevent light from passing through the reflection layer and interfering with the light exposure or endangering uninvolved road users.

(20) The reflector element 10 is preferably formed such that it adjoins the first side 5 of the optical element 10 in a form-fitting manner. Similarly to the first described variant, the reflection layer 9 has at least one focal point due to the form of the reflector element 10, wherein the luminous element 4 in the mounted state is preferably arranged in a focal point of the reflection layer 9. The optical element 1 and/or reflector element 10 are to be formed accordingly as free-form faces of known type.

(21) FIG. 3 shows a variant of the invention in which the optical element 1 has on its second side 11 (that is to say the side facing the laser light source 3 in the mounted state) a light-impermeable screen device 12. This screen device 12 covers the second side 11 at least in part, wherein it is arranged in the illustrated exemplary embodiment beneath a horizontal plane 100 running through the luminous element 4. The horizontal plane 100 in the figures runs normal to the drawing plane and is therefore identifiable merely as a dot-and-dash line. Of course, other embodiments are also possible depending on the desired light function.

(22) The screen device 12 can be formed arbitrarily, for example as a light-impermeable coating or as a separate screen, which is glued to the optical element 1 or fitted thereto in another way or is mechanically held thereon. The screen device 12 allows the generation of a light/dark transition, whereby various light functions, such as dipped beam, fog light, etc., can be provided.

(23) In the variant according to FIG. 3, the form of the first side 5 facing away from the laser light source 3 is different from the embodiment in FIGS. 1 and 2. Here, the form is no longer similar to a spherical cap, but is different, which is discernible on the basis of the sketched beam paths.

(24) It should be noted that the optical element 1, besides the integral embodiment illustrated here (apart from coatings or screen elements or the like), can also be formed in variants such that it consists of a number of parts, which for example are glued together or welded together and have different optical properties (refractive index or the like). With such a multi-part optical element 1, the solid body would thus be formed in a number of parts for example, wherein the separate components can be manufactured with different optical properties. Accordingly, the reflection layer 9 (or the absorption layer 6) can then also be introduced as separate components.

(25) A variant that is formed favourably with such a multi-piece element is illustrated in FIG. 4. In this case the optical element 1 is formed as a hollow body. It thus has a sleeve, which preferably predominantly consists of a transparent, light guiding material. The reflection layer 9 is formed on the rear wall 22, which is arranged on the first side 5. The reflection layer 9 is formed in the illustrated exemplary embodiment on the inner side of the rear wall 22 facing the luminous element 4. An absorption layer 6 is applied to the outer side of the rear wall 22 facing away from the luminous element 4 in order to prevent laser light or light emitted by the luminous element 4 from passing through the rear wall 22. Of course, this is just one of a number of embodiments—for example the reflection layer 9 can be applied to the outer side of the rear wall 22 and also covered by an absorption layer 6.

(26) The screen device 12 described further above can also be provided in variants with a hollow body besides the described embodiments by manufacturing the hollow body from a thermo-plastic. In this case, the region of the delimitation face 21 constituting the screen device 12 (preferably beneath a horizontal plane 100 running through the luminous element 4) is sprayed with a light-impermeable material in a multi-component spraying method. No further measures than have to be taken in order to provide a screen device 12.

(27) In accordance with the variant of FIG. 4, the optical element can be formed in a number of pieces, for example by forming the rear wall 22 and the rest of the optical element 1 separately. In such a case the rear wall can be manufactured for example from a light-impermeable material, whereby the absorbing layer 6 can be saved when the reflection layer 9 is arranged on the inner side of the rear wall 22. Whereas the rear wall 22 thus constitutes a reflector, the rest of the optical element 1 substantially forms a cover for this reflector with a mount for the luminous element 4. Of course, however, the rear wall 22 and the rest of the optical element 1 can also form a common structural unit.

(28) Ambient air is usually located within the hollow body, which does not have to be gas-tight. Of course, the hollow body can also be gas-tight, such that the interior can be filled with other gases, which for example influence the reflection behaviour.

(29) The variants described in FIGS. 1 to 3 can be provided both with a solid body and with a hollow body.

(30) FIG. 5 shows a variant of the invention in which the optical element 1 is installed in a light source module 16 for a vehicle headlight 2. The optical element 1 according to this embodiment has a receptacle for the luminous element 4 in the form of a cavity 8. This means that the luminous element 4 is surrounded completely by the optical element 1. The delimitation face 21 (or first side 11) is slightly concave in the variant according to FIG. 5.

(31) The light source module 16 has a laser light source 3 inclusive of assigned cooling devices 17 (for example cooling ribs, water cooling or the like), wherein the laser light source 3 and the optical element 1 are arranged jointly on a carrier element 18. The carrier element 18 can consist of a heat-conductive material and/or additional cooling elements, such as cooling ribs 19.

(32) The light source module 16 as a whole can be installed in a vehicle headlight 2. Such a variant is illustrated in FIG. 6. Here, it can be seen that, thanks to the reflection layer 9 of the optical element 1, a utilisation of the light radiated by the luminous element 4 in the main radiation direction 300 of the laser vehicle headlight 2 is made possible, since this light is guided by the reflection layer 9 in the direction of the reflector 20 of the vehicle headlight 2. Furthermore, it can be seen that light emitted directly by the luminous element 4 is projected differently (projection A in FIG. 6) from light that reaches the reflector 20 of the vehicle headlight 2 via the reflection element 10 (projection B in FIG. 6).

(33) The optical element 1 is favourably arranged in the vehicle headlight 2 in such a way that the luminous element 4 is positioned in a focal point of the reflector 20. Due to the combination of the shaping of the reflector 20 and of the optical element 1, different light distribution patterns can be provided. Theoretically, the light patterns of the light emitted directly by the luminous element 4 can also be aligned with the light pattern of the light radiated via the reflection element 10.