RADIATION-EMITTING DEVICE, AND PROJECTOR EQUIPPED THEREWITH

Abstract

A radiation-emitting device includes an optoelectronic component for emitting first electromagnetic radiation. The radiation-emitting device also includes a conversion element having an entrance surface and an exit surface. The radiation-emitting device further includes a dielectric mirror on the exit surface. The radiation-emitting device is configured such that first radiation emitted by the component during operation enters the conversion element via the entrance surface. The conversion element is configured for converting the first radiation into second electromagnetic radiation, which subsequently exits the conversion element via the exit surface. The dielectric mirror is transmissive to second radiation that is incident at angles of incidence in a predefined first angle range, and is reflective for second radiation that is incident at angles of incidence in a predefined second angle range.

Claims

1. A radiation-emitting device, comprising an optoelectronic component for emitting first electromagnetic radiation, a conversion element having an entrance surface and an exit surface, a dielectric mirror on the exit surface, wherein the radiation-emitting device is configured such that first radiation emitted by the component during operation enters the conversion element via the entrance surface, the conversion element is configured for converting the first radiation into second electromagnetic radiation, which subsequently exits the conversion element via the exit surface, the dielectric mirror is transmissive to second radiation that is incident at angles of incidence in a predefined first angle range, and is reflective for second radiation that is incident at angles of incidence in a predefined second angle range.

2. The radiation-emitting device as claimed in claim 1, wherein the first angle range comprises all angles of incidence of between 0° and α inclusive, measured with respect to a normal to the dielectric mirror, the second angle range comprises all angles of incidence of at least β, measured with respect to the normal to the dielectric mirror, where β >_ α holds true.

3. The radiation-emitting device as claimed in claim 1, wherein the conversion element is configured for fully converting the first radiation into the second radiation.

4. The radiation-emitting device as claimed in claim 1, further comprising an optical element disposed downstream of the conversion element and the dielectric mirror and configured for deflecting the second radiation.

5. The radiation-emitting device as claimed in claim 1, wherein the conversion element has scattering centers for redistributing the radiation reflected back from the dielectric mirror into the conversion element.

6. The radiation-emitting device as claimed in claim 1, wherein a second mirror is arranged on the entrance surface of the conversion element, the second mirror is reflective for the second radiation and transmissive to the first radiation.

7. The radiation-emitting device as claimed in claim 1, wherein a third mirror is arranged on the exit surface, the third mirror is reflective for the first radiation.

8. The radiation-emitting device as claimed in claim 1, wherein the dielectric mirror is reflective for the first radiation.

9. The radiation-emitting device as claimed in claim 1, wherein the conversion element is arranged at a distance from the component, such that during operation first radiation from the component frstly traverses a distance through air before it impinges on the conversion element.

10. The radiation-emitting device as claimed in claim 1, wherein the conversion element is arranged indirectly or directly on the component.

11. The radiation-emitting device as claimed in claim 1, further comprising a second optoelectronic component for emitting third electromagnetic radiation, wherein the radiation-emitting device is configured such that third radiation emitted by the second component during operation penetrates into the conversion element via the exit surface of the conversion element, the conversion element is configured for converting the third radiation, the dielectric mirror is transmissive to the third radiation.

12. The radiation-emitting device as claimed in claim 11, wherein an antireflection coating for the third radiation is applied on the exit surface.

13. A projector comprising a radiation-emitting device as claimed in claim 1.

Description

[0057] In the figures:

[0058] FIGS. 1 to 6 show various exemplary embodiments of the radiation-emitting device, and

[0059] FIG. 7 shows one exemplary embodiment of a projector.

[0060] FIG. 1 shows a first exemplary embodiment of the radiation-emitting device 100. The device 100 comprises an optoelectronic component 1, in the present case a light-emitting diode (LED), which emits first radiation in the form of blue light during operation.

[0061] A laminar conversion element 2 comprising an entrance surface 20 and an exit surface 21 is disposed downstream of the component 1 in the beam direction. The conversion element 2 is for example a ceramic conversion element composed of sintered conversion material. The first radiation from the component 1 enters the conversion element 2 via the entrance surface 20 and is partly or completely converted into second radiation, for example green light, in said conversion element. The second radiation can then exit the conversion element 2 via the exit surface 21.

[0062] A dielectric mirror 3 comprising a plurality of dielectric layers having different refractive indices is arranged on the exit surface 21. The dielectric mirror 3 is configured such that it is transmissive to second radiation that is incident at angles of incidence in a first angle range of between 0° and α inclusive, and is reflective for second radiation that is incident at angles of incidence in a second angle range outside the first angle range (from β to 90°). In the present case, the value for α is 30°, for example. The value for β is 35°, for example. The dielectric mirror 3 can be reflective for the first radiation, independently of the angle of incidence.

[0063] An optical element 4 is disposed downstream of the conversion element 2 in the beam direction. In the present case, the optical element 4 is a mirror that deflects the radiation that has passed through the dielectric mirror 3. By way of example, the second radiation is directed onto a projection surface, such as a projection screen, for instance. The device 100 shown can be used in a projector. Through the angle-selective dielectric mirror 3, the second radiation (green light) is emitted in a small angle range, as a result of which the device 100 described is particularly well suited to projection applications.

[0064] FIG. 2 shows a second exemplary embodiment of the radiation-emitting device 100. The latter differs from that from FIG. 1 in that the conversion element 2 comprises scattering centers in the form of scattering particles. These scatter and redistribute the radiation reflected back from the dielectric mirror 3, such that when it is next incident on the dielectric mirror 3, said radiation impinges on the dielectric mirror 3 in the first angle range, if appropriate. The scattering particles can be distributed uniformly in the conversion element 2. The scattering particles are for example scattering pores in a ceramic converter.

[0065] Instead of or in addition to scattering centers in the form of scattering particles within the conversion element, the entrance surface 20 and/or the exit surface 21 can also be structured, as a result of which a redistribution of the radiation reflected back is achieved.

[0066] FIG. 3 shows a third exemplary embodiment of the radiation-emitting device 100. Here, in comparison with the exemplary embodiment in FIG. 2, a second dielectric mirror 5 is arranged on the entrance surface 20 of the conversion element 2. The second dielectric mirror 5, too, comprises a plurality of dielectric layers. The second dielectric mirror 5 is reflective for the second radiation and transmissive to the first radiation. This preferably applies to all angles of incidence. This prevents the second radiation from leaving the conversion element 2 again via the entrance surface 20.

[0067] FIG. 4 shows a fourth exemplary embodiment of the radiation-emitting device 100. Here, in addition to the exemplary embodiment in FIG. 3, a third dielectric mirror 6 is arranged on the exit surface 21, between the dielectric mirror 3 and the exit surface 21. The third dielectric mirror 6 is reflective for the first radiation and transmissive to the second radiation, preferably independently of the angle of incidence. This prevents the first radiation from leaving the conversion element 2 via the exit surface 21.

[0068] Instead of a second 5 and third 6 dielectric mirror having a plurality of dielectric layers, it is also possible to use some other second mirror 5 and third mirror 6 having the desired properties. By way of example, such a second mirror 5 and such a third mirror 6 each comprise a plurality of dielectric layers.

[0069] FIG. 5 shows a fifth exemplary embodiment of the radiation-emitting device 100. Here, unlike in the preceding exemplary embodiments, the conversion element 2 is not arranged at a distance from the optoelectronic component 1. Rather, here the conversion element 2 is arranged and secured indirectly on the component 1.

[0070] FIG. 6 shows a sixth exemplary embodiment of the radiation-emitting device 100. Here, besides the first optoelectronic component 1, the device 100 comprises a second optoelectronic component 11, which emits third radiation. In the present case, the third radiation is likewise blue light. The device 100 is configured such that the third radiation emitted by the second component 11 penetrates into the conversion element 2 via the exit surface 21 of the conversion element 2. The third radiation previously passes through the optical element 4, which in the present case is formed by a semi-transmissive mirror. In order to be able to penetrate into the conversion element 2, in the present case the dielectric mirror 3 is transmissive to the third radiation, preferably at all angles of incidence.

[0071] In order to reduce reflection of the third radiation at the dielectric mirror 3, an antireflection coating 7 for the third radiation is applied on the side of the dielectric mirror 3 facing away from the conversion element 2.

[0072] FIG. 7 shows one exemplary embodiment of a projector comprising the radiation-emitting device 100 from FIG. 1. The radiation-emitting device 100 generates green light by means of conversion. Furthermore, the projector comprises a third optoelectronic component 12, in the present case in the form of a light-emitting diode, which generates intrinsically blue light, and a fourth optoelectronic component 13, likewise in the form of a light-emitting diode, which generates intrinsically red light. Each of the components 1, 12, 13 is assigned a mirror 4 for deflecting the respective light. The mirrors 4 are in particular each transmissive to the radiation from the preceding component. In this regard, for example, the mirror 4 assigned to the green-emitting component 1 is transmissive to blue light and reflective for green light. The mirror 4 assigned to the red-emitting component 13 is preferably transmissive to blue and green light and reflective for red light. The projector furthermore comprises a lens 40, with the aid of which the light is projected onto a projection screen 8.

[0073] The priority of German Patent Application 102020204540.2 is claimed, which is hereby incorporated by reference.

[0074] The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments. Rather, the invention encompasses any novel feature and also any combination of features, which in particular includes any combination of features in the patent claims, even if these features or this combination itself are/is not explicitly specified in the patent claims or exemplary embodiments.

TABLE-US-00001 List of reference signs 1 2 3 4 5 6 7 8 11 12 13 20 21 40 100 α β (First) optoelectronic component Conversion element (First) dielectric mirror Optical element Second dielectric mirror Third dielectric mirror Antireflection coating Projection screen Second optoelectronic component Third optoelectronic component Fourth optoelectronic component Entrance surface Exit surface Lens Radiation-emitting device Angle Angle