Fluorescence converter device and corresponding manufacturing process

Abstract

Fluorescence converter device (1), comprising at least one light source (2); a thermally conductive support structure (4) with an array of through holes (8) in conical depressions on both sides (6); a first microlens array (3); and a second microlens array (5); wherein the microlenses of the microlens arrays are each located in the conical depressions (6) on opposite sides of the through-holes (8), such that the optical axes of the microlenses coincide with the centers of the through-holes (8); and a fluorescence converter (7) is inserted into the through holes (8).

Description

[0001] The present invention relates to a fluorescence converter device and a corresponding manufacturing process. State of the art

[0002] Although any optical components can be used, the present invention and the underlying problem are explained using components for lighting devices.

[0003] Known methods for guiding a laser beam include, for example, in DE 10 2013 222 834 A1, a mirror arrangement with movable mirrors for generating an angle of incidence of the laser beam on a focusing optic for setting a lateral offset of the laser beam.

[0004] Micromirror applications for glare-free high-beam headlights, on the other hand, require the highest radiance and contrast values ​​from the light sources used to achieve the desired high luminous flux. Currently, focused blue lasers are used in conjunction with fluorescent converter plates for this purpose. This means the laser, with its focus, generates the desired light distribution on the converter, which is then projected onto the driving scene in front of the vehicle using secondary optics. Due to scattering within the material, the opaque fluorescent converters can exhibit a significant widening of the laser spot and insufficient contrast, i.e., an inadequate intensity ratio between illuminated and unilluminated areas. At high radiances in the laser spot, local heating of the converter can occur. This can drastically reduce the conversion efficiency, and the efficiency can decrease with increasing temperature.

[0005] Fluorescence converter devices, some of which have features of the fluorescence converter device according to claim 1, are also known from documents US 2011 / 0 249 460 A1 and DE 10 2011 006 643 A1. Disclosure of the invention

[0006] The present invention discloses a fluorescence converter device according to claim 1 and a corresponding manufacturing method according to claim 9.

[0007] According to a first aspect of the present invention, the fluorescence converter device comprises at least one light source, a thermally conductive support structure with an array of through-holes in conical depressions on both sides, a first microlens array, and a second microlens array, wherein the microlenses of the microlens arrays are located in the conical depressions on opposite sides of the through-holes, such that the optical axes of the microlenses coincide with the centers of the through-holes, and a fluorescence converter is inserted into the through-holes. This increases both the conversion efficiency and the radiance as well as the contrast while simultaneously preventing the fluorescence converter from heating up.

[0008] According to a second aspect of the present invention, the method for manufacturing a fluorescence converter device comprises the steps of providing a thermally conductive support structure, producing through-holes with conical recesses on both sides in the thermally conductive support structure, placing a fluorescence converter in the through-holes, placing microlenses of a first microlens array in the conical recesses on a first side of the through-holes, and placing a second microlens array in the conical recesses on a second side of the through-holes opposite the first. The fluorescence converters described above can thus be manufactured efficiently on an industrial scale.

[0009] Preferred further training courses are the subject of the respective sub-claims. Advantages of the invention

[0010] The invention makes it possible to increase conversion efficiency, radiance, and contrast while simultaneously improving heat dissipation from the converter material. High-performance lighting applications, such as scanning headlight modules for motor vehicles, require particularly high radiance.

[0011] According to a preferred embodiment, the through-holes in the fluorescence converter device are arranged at intervals of 50–1500 micrometers. This allows for a wide variety of microlens arrangements and thus a wide range of applications.

[0012] According to a preferred embodiment, the through-holes in the fluorescence converter device are arranged equidistantly. This enables particularly efficient fabrication of the fluorescence converter device, and standard manufactured microlens arrays can be used.

[0013] According to a preferred embodiment, the diameter of the through-holes in the fluorescence converter device is 50–500 micrometers. This allows the production of fluorescence converter devices that permit a wide variety of beam widths.

[0014] According to a preferred embodiment, the microlenses of the microlens arrays in the fluorescence converter device are either spherical or aspherical lenses. Depending on the application, aspherical lenses can prevent or reduce aberrations, while the use of spherical lenses can lower manufacturing costs.

[0015] According to a preferred embodiment, the microlenses of the microlens arrays of the fluorescence converter device have a hexagonal, square, or rectangular shape. This allows their outer contours to abut, i.e., practically achieving a fill factor of 1 and enabling the production of particularly space-saving devices.

[0016] According to a preferred embodiment, the microlenses of the microlens arrays of the fluorescence converter device are made of cycloolefin copolymer plastic, organic glass, mineral glass, or transparent ceramic. Microlenses made of cycloolefin copolymer plastic are preferred because they exhibit high strength and hardness, as well as low density and high transparency.

[0017] According to a preferred embodiment, the thermally conductive support structure of the fluorescence converter device is made of silicon, metal, or heat-absorbing ceramic. Silicon is preferred because it allows for particularly precise machining. Brief description of the drawings

[0018] The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawings. These show: Fig. 1: A schematic cross-sectional representation illustrating a fluorescence converter device according to a first embodiment of the present invention; and Fig. 2: a schematic flowchart to explain a method for manufacturing a fluorescence converter device according to a further embodiment. Embodiments of the invention

[0019] In the figures, identical reference symbols denote identical or functionally equivalent elements.

[0020] Fig. Figure 1 is a schematic representation to illustrate a fluorescence converter device according to a first embodiment of the present invention in cross-section.

[0021] Fig. Figure 1 shows a fluorescence converter device 1 with light sources 2, a first microlens array 3, a thermally conductive support structure 4 with conical depressions 6 and fluorescence converters 7 in the through-holes 8, as well as with a second microlens array 5.

[0022] A thermally conductive support structure 4 (for example, a plane-parallel plate made of silicon or metal) is designed to have equidistant through-holes 8 (diameter, for example, 30 micrometers) with conical countersinks 6 on both sides at defined intervals (for example, 100 micrometers) on both sides. A fluorescence converter 7 is inserted into the through-holes 8. A microlens array (made, for example, of cycloolefin copolymer plastics) is placed on opposite sides above the array of through-holes 8, such that the optical axes of the respective microlenses coincide with the centers of the through-holes 8. The microlenses are designed so that their outer contours meet, i.e., practically a fill factor of 1 is achieved (for example, hexagonal, square, or rectangular).

[0023] The arrangement is designed such that, upon perpendicular irradiation with a collimated laser beam (beam waist of the laser beam on the structure, for example, 500 micrometers), the first microlens array 3 focuses the laser light onto the fluorescence converter 7 and converts it to white light. Through scattering, the white light fills the through-holes 8. This then acts as a Lambertian radiator, which is imaged by the second microlens array 5 in such a way that the opening angle of the radiation emitted by the arrangement in the far field (for example, 1000 millimeters) is minimized. By reducing the opening angle of the emitted radiation with the second microlens array 5, the portion of the radiation usable for the application increases. High efficiency is achieved through the use of the first microlens array 3 with a high fill factor.

[0024] The excellent cooling of the fluorescence converter 7 by the support structure 4 allows operation at high radiances. The very high contrast achievable is particularly advantageous, as it is made possible by the fact that the material of the support structure 7 prevents scattered radiation from propagating laterally within the support structure 7.

[0025] Fig. Figure 2 shows a schematic flowchart to explain a method for manufacturing a fluorescence converter device according to a further embodiment. The method according to Fig. 2 is suitable for manufacturing the devices described above and can be modified according to all variants and further developments described with regard to these devices and vice versa.

[0026] In step S01, a thermally conductive support structure 4 is provided. In step S02, through-holes 8 with conical countersinks 6 on both sides are machined into this support structure 4, and in step S03, fluorescence converters 7 are placed in the through-holes 8. In step S04, microlenses of a first microlens array 3 are placed in the conical countersinks on one side of the through-holes 8, and in step S05, a second microlens array 5 is placed in the conical countersinks 6 on a second side of the through-holes 8, opposite the first.

[0027] Steps S01 to S5 are preferably performed in the order according to their numbering.

[0028] Although the present invention has been described with reference to preferred embodiments, it is not limited thereto. In particular, the materials and topologies mentioned are only examples and are not limited to the examples described.

[0029] Particularly preferred further applications for the fluorescence converter device according to the invention are, for example, in lighting systems used in the automotive industry or similar applications.

Claims

[1] Fluorescence converter device (1) comprising at least one light source (2); a thermally conductive support structure (4) with an array of through holes (8) in conical depressions on both sides (6); a first microlens array (3); and a second microlens array (5); wherein the microlenses of the microlens arrays are each located in the conical depressions (6) on opposite sides of the through-holes (8), such that the optical axes of the microlenses coincide with the centers of the through-holes (8); and a fluorescence converter (7) is inserted into the through holes (8). [2] Fluorescence converter device (1) according to claim 1, wherein the through holes (8) are arranged at a distance of 50 - 1500 micrometers. [3] Fluorescence converter device (1) according to claim 1 or 2, wherein the through holes (8) are arranged equidistantly. [4] Fluorescence converter device (1) according to one of the preceding claims, wherein the diameter of the through holes (8) is 50 - 500 micrometers. [5] Fluorescence converter device (1) according to any of the preceding claims, wherein the microlenses of the microlens arrays are spherical or aspherical lenses. [6] Fluorescence converter device (1) according to any of the preceding claims, wherein the microlenses of the microlens arrays have a hexagonal, square or rectangular shape. [7] Fluorescence converter device (1) according to any of the preceding claims, wherein the microlenses of the microlens arrays are made of cycloolefin copolymer plastic, organic glass, mineral glass or transparent ceramic. [8] Fluorescence converter device (1) according to one of the preceding claims, wherein the thermally conductive support structure (4) is made of silicon, metal or heat-absorbing ceramic. [9] Method for manufacturing a fluorescence converter device (1) comprising the steps: Providing a heat-conducting support structure (4); Making through holes (8) with conical countersinks (6) on both sides in the heat-conducting support structure (4); Attaching a fluorescence converter (7) in the through holes (8); Attaching microlenses of a first microlens array (3) in the conical recesses (6) on a first side of the through holes (8) and Attaching a second microlens array (5) in the conical depressions (6) on a second side of the through holes (8) opposite the first.

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