Collimator, and luminaire comprising a collimator
The collimator with an annular recess and partial surfaces addresses the challenge of achieving ideal light distribution and compactness, using PMMA or glass materials with controlled angles and microlenses for enhanced light emission.
Patent Information
- Application Number
- PCT/EP2025/069510
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-07-12
- Filing Date
- 2025-07-09
- Publication Date
- 2026-01-15
AI Technical Summary
Existing collimators fail to achieve an ideal light distribution with a homogeneous intensity within a predefined light cone, free of reflections and intensity variations, while maintaining a compact design.
A collimator design featuring an annular recess with two partial surfaces forming a reflective surface, allowing multiple light paths to achieve a compact diameter while maintaining homogeneous light distribution, using materials like PMMA or glass with controlled refractive angles and microlenses for diffusing structures.
The design produces a homogeneous light distribution with a sharp intensity drop outside the cone, achieving a compact and efficient light emission with reduced diameter and improved robustness against production and assembly tolerances.
Smart Images
Figure EP2025069510_15012026_PF_FP_ABST
Abstract
Description
[0001] Collimator and lamp with a collimator
[0002] The invention relates to a collimator for collimating light by means of several optical surfaces, each forming optical interfaces with a change in optical density, wherein the collimator extends along a longitudinal axis and the optical surfaces comprise a light entry surface, a light exit surface and a reflection surface, wherein the reflection surface is designed as a lateral surface of a truncated shape having a (conceivable) base surface and a top surface, wherein the base surface faces the light exit surface and the top surface coincides at least partially with the light entry surface.
[0003] Furthermore, the invention relates to a lamp, in particular a pocket or headlamp, with a lamp head comprising at least one collimator and a light source which is oriented such that its emitted light is directed towards a light entry surface of the collimator during intended use.
[0004] Technological background
[0005] Collimators for collimating light are known in particular in connection with portable or mobile luminaires according to the prior art, whereby the various collimators for different application areas have different geometries.
[0006] Lenses with a flat or concave light entry surface and a convex light exit surface are known, for example.
[0007] Furthermore, so-called total internal reflection collimators (TIR collimators) are known, which have a converging lens and a reflector section that completely surrounds the converging lens. The light-entry surface of such a TIR collimator is generally divided into two sections: a flat, convex, or concave light-entry surface of the converging lens and a substantially cylindrical light-entry surface of the reflector section. The central converging lens and the reflector section also have different light-exit surfaces, which is why TIR collimators typically have a complex geometry.
[0008] Furthermore, straight-walled optical fibers are known which have a frustoconical cross-section with a flat light entry surface and a flat light exit surface.
[0009] Compound parabolic concentrator collimators (CPC collimators) are also known, which also have a flat light entry surface and a flat light exit surface, but whose side wall is convex.
[0010] Finally, collimators of this type are known as so-called Dielectric Total Internal Reflection (DTIR) collimators. In contrast to known optical fibers and CPC collimators, DTIR collimators have a light-emitting surface that is completely convex. For example, such a DTIR collimator is disclosed in WO 2022 / 214127 Al.
[0011] While existing collimators allow for the collimation of light, an ideal light distribution has not yet been achieved. An ideal light distribution is defined as one that, within a predefined light cone, exhibits a substantially constant or homogeneous light intensity, is free of reflections, lines, and other rings with locally varying light intensity, and has a clearly defined boundary. Outside this boundary, and thus outside the intended light distribution, the light intensity should ideally disappear completely.
[0012] Description of the invention: Problem, solution, advantages
[0013] The object of the invention is to propose a collimator and a portable lamp with a collimator which, compared to the prior art, has a comparatively more compact design for a given overall height due to a comparatively smaller diameter. This object is achieved by the collimator according to claim 1 and by the lamp according to claim 14. According to the invention, the collimator has an annular recess surrounding the light-entry surface, such that the collimator comprises a first partial collimator with a first partial surface and a second partial collimator with a second partial surface, wherein the partial surfaces form the reflection surface and are spaced axially and radially apart from one another.
[0014] Directional specifications within the scope of the present application, in particular radial, axial and tangential, refer to a cylindrical coordinate system spanned by the longitudinal axis of the collimator.
[0015] An annular recess is understood to be a recess that completely encloses the first partial stump, regardless of its specific cross-sectional geometry, with respect to a cross-section perpendicular to the longitudinal axis of the collimator. Thus, the reflective surface has an annular offset, in particular an annular step, which—viewed from the light-emitting surface of the collimator—reduces the diameter of the stump section by section.
[0016] The reflective surface, formed section by section by the first and second partial surface of the collimator, results in at least three different light paths within the collimator. In the first light path, light from a light source couples into the light-entry surface and is refracted only to the extent that it couples out directly at the light-emission surface. In contrast, light paths that couple into the light-entry surface at a larger angle of incidence are refracted to such an extent that they are reflected at the second partial surface and then couple out at the light-emission surface.The recess creates a third light path, in contrast to the prior art. Light coupling at an even wider angle to the light-entry surface undergoes a first reflection at the first partial surface and a second reflection at the second partial surface before exiting at the light-emission surface. This widens the light emission, allowing the collimator to have a significantly smaller diameter compared to the prior art while maintaining the same light emission. Advantageous embodiments of the invention are described below and in the dependent claims.
[0017] In particular, it is provided that the stump has a single annular recess. This single annular recess preferably surrounds the light-entry surface such that the stump has a first partial stump with a first partial surface and a second partial stump with a second partial surface, wherein the partial surfaces form the reflection surface and are spaced axially and radially apart from each other. In this embodiment, the collimator is otherwise free of further annular recesses of the partial surfaces, so that the stump has exactly two partial stumps, namely the first partial stump and the second partial stump.
[0018] According to an advantageous embodiment, the first partial truncated section has a first partial base and a first partial top surface, each bounded by a perimeter line, wherein each secant which a) intersects the perimeter line of the first partial base and the perimeter line of the first partial top surface and b) lies within an axial plane and c) does not intersect the longitudinal axis in a section between the first partial base and the first partial top surface is inclined at an angle α to the longitudinal axis of the collimator, wherein α is in particular: 0 < α < 8°, preferably 0 < α < 6°.
[0019] Similarly, it is preferably provided that the second partial truncated section has a second partial base surface and a second partial top surface, each bounded by a perimeter line, wherein each secant that a) intersects the perimeter line of the second partial base surface and the perimeter line of the second partial top surface, and b) lies within an axial plane, and c) does not intersect the longitudinal axis in a section between the second partial base surface and the second partial top surface, is inclined at an angle to the longitudinal axis of the collimator, wherein β in particular: 0 < β < 7°, preferably 0 < β < 5°. The partial base surfaces each face the light-emitting surface and the partial top surfaces each face the light-intake surface of the collimator.
[0020] In all cases, the perimeter line forms the outer boundary of the respective partial cover surface or the respective partial base surface addressed, and an axial plane denotes a plane which contains the longitudinal axis of the collimator.
[0021] Thus, every secant line connecting the start and end points of a profile of one of the partial lateral surfaces within an axial plane is inclined at the angle α or β to the longitudinal axis of the collimator. A profile is defined here as the line of intersection between a partial lateral surface and an axial plane.
[0022] Furthermore, it is preferably provided that each tangent of the first partial lateral surface and / or each tangent of the second partial lateral surface, which runs within an axial plane, is inclined at an angle 5 to the longitudinal axis of the collimator, wherein 5 is: 0 < 5 < 12°, preferably 0 < 5 < 10°.
[0023] Accordingly, the reflective surface, in particular the first partial surface and / or the second partial surface, can also be completely or partially convex or concave with respect to the longitudinal axis of the collimator, although the convexity or concavity is limited due to the restriction of the tangent angle 5. In other words, the shape of the reflective surface, in particular the first partial surface and / or the second partial surface, deviates only slightly from a straight design.
[0024] In an advantageous embodiment, the recess of the collimator has an end face that connects the first partial surface with the second partial surface. This end face is preferably designed such that, during normal use of the collimator, it lies outside all light paths. In particular, the end face is inclined at an average angle y relative to the longitudinal axis of the collimator, where the angle y is preferably 45° < y < 90°. This means that the end face of the recess does not interact with the intended light paths in any conceivable scenario. The average angle y is preferably an angle between the longitudinal axis of the collimator and a connecting line that intersects the periphery of the first partial base surface and the periphery of the second partial top surface and lies within an axial plane.
[0025] Depending on the intended use of the collimator, it is preferably provided that the truncated sections are designed as a truncated cone with a circular cross-section, as a truncated pyramid with a polygonal cross-section, or as a truncated elliptical cone with an elliptical cross-section. Preferably, the truncated sections are rotationally symmetrical.
[0026] In particular, it is provided that the light entry surface of the collimator is designed to be smaller (or true to scale or scaled) than the base area of the stump.
[0027] Preferably, the light-entry surface and / or the light-emission surface are designed as flat or curved, in particular convex or concave, surfaces. The reflection surface, in particular the first partial surface and / or the second partial surface, is preferably designed as a flat or curved, in particular convex or concave, surface along a longitudinal section running parallel to the longitudinal axis of the collimator. The surface may also have concave and convex subsections.
[0028] It is further preferred that the light-entry surface is flat and / or that the light-emission surface is convex, in particular spherical. A spherical shape means that the light-emission surface is semi-spherical and / or cap-shaped along a radius R, with the center of the radius lying on the longitudinal axis of the collimator.
[0029] The collimator is preferably integrated together with at least one other optical element in a common front plate, which is inserted into the head of the luminaire. To connect the collimator to the front plate, a retaining rim is preferably formed between the light-emitting surface and the stub, the retaining rim being axially and radially spaced from the base of the stub. The front plate thus preferably has several collimators and is particularly designed as a single, solid body.
[0030] Under ideal conditions, the collimator can produce a homogeneous light distribution that has an almost constant intensity in a selected light cone and a sharp drop to almost negligible intensity outside of it.If a softer light falloff is desired, or if the light source is not ideal (e.g., rectangular or with uneven brightness or color), or if the robustness of the luminaire's light distribution against production and assembly tolerances is to be increased while still achieving a homogeneous light distribution, a particular embodiment provides that all optical surfaces, or a subset thereof, have a light-diffusing structure, at least partially or across their entire surface. In the case of refracting surfaces, the light-diffusing structure preferably comprises concave and / or convex microlenses and / or (random) roughness, and in the case of reflective surfaces, preferably concave and / or convex microlenses. Reflective surfaces include, in particular, the reflection surface, and refracting surfaces include, in particular, the light-intake surface and the light-out surface.Random roughness can be introduced into the material of an injection mold for the production of the collimator with the desired characteristic values, for example by sandblasting, etching or spark erosion, while microlenses are created by milling or five-axis turning of the injection mold.
[0031] According to an advantageous embodiment, the collimator is designed as a solid body, particularly as a one-piece solid body. The collimator preferably consists of a dielectric, especially polymethyl methacrylate (PMMA), silicone, or glass. These materials, especially PMMA, are easy to process and provide the desired optical properties for collimating the light. In all cases, the refractive index inside the collimator is sufficiently high to ensure total reflection of the light along all light paths at the reflective surfaces. According to a particularly preferred embodiment of the invention, the ratio of the height h2 of the second truncated section to the height h1 of the first truncated section is: 15 < < 60, particularly 20 < < 50.
[0032] List of characters
[0033] A specific embodiment of the invention is explained below with reference to the figures. These show:
[0034] Fig. aa a first cross-sectional view of a first collimator;
[0035] Fig. 1b shows two detailed views of the first collimator;
[0036] Fig. lc shows a third detailed view of the first collimator;
[0037] Fig. 2 shows a second cross-sectional view of the first collimator;
[0038] Fig. 3 shows a cross-sectional view of a second collimator;
[0039] Fig. 4 shows a cross-sectional view of a third collimator;
[0040] Fig. 5 shows a cross-sectional view of a light fixture.
[0041] Detailed description of the characters
[0042] Fig. 1a shows a collimator 100 for collimating light by means of several optical surfaces 10, each forming an optical interface with a change in optical density. The collimator 100 extends rotationally symmetrically along a longitudinal axis A. The optical surfaces 10 comprise a flat light-entry surface 101, a convex light-emission surface 102, and a reflection surface 103, wherein the reflection surface 103 is formed as the lateral surface 11 of a truncated shape 12, which has a base 13 and a top surface 14, the base 13 facing the light-emission surface 102 and the top surface 14 coinciding at least partially with the light-entry surface 101. Below the light entry surface 101 a light source 15 is arranged which, when used as intended, emits light that couples into the light entry surface 101 and is collimated within the collimator 100.An air gap 16 is arranged between the light source 15 and the light-entry surface 101. The stub 12 has an annular recess 17 that surrounds the light-entry surface 101, such that the stub 12 comprises a first partial stub 181 with a first partial surface 191 and a second partial stub 182 with a second partial surface 192. The partial surfaces 191 and 192 form the reflection surface 103 and are spaced axially and radially apart from each other with respect to the longitudinal axis A of the collimator 100.
[0043] Fig. 1b shows two (not to scale) detail views of the partial stubs 181, 182. The reference numerals of partial stubs 182 are given in square brackets. The upper detail view shows a cross-sectional view of partial stubs 181, 182, and the lower detail view shows a cross-sectional view onto the cross-sectional plane AA.
[0044] The first partial truncated section 181 has a first partial base area 131 and a first partial top surface 141, each bounded by a perimeter line 3111, 3112, wherein each secant S which a) intersects the perimeter line 3121 of the first partial base area 131 and the perimeter line 3111 of the first partial top surface 141 and b) lies within an axial plane and c) does not intersect the longitudinal axis A in a section between the first partial base area 131 and the first partial top surface 141
[0045] The second partial truncated surface 182 intersects the first partial cover surface 131 and the first partial cover surface 141 at an angle α to the longitudinal axis A of the collimator 100. The drawing plane corresponds to an axial plane. Similarly, the second partial truncated surface 182 has a second partial base surface 132 and a second partial cover surface 142, each bounded by a perimeter line 3112, 3122, wherein each secant S that a) intersects the perimeter line 3122 of the second partial base surface 132 and the perimeter line 3112 of the second partial cover surface 142 and b) lies within an axial plane and c) does not intersect the longitudinal axis A in a section between the second partial base surface and the second partial cover surface 142 is defined as follows:
[0046] The first partial surface 132 and the second partial surface 142 intersect at an angle β relative to the longitudinal axis A of the collimator 100. Each tangent T of the first partial surface 191 and each tangent T of the second partial surface 192, which lies within an axial plane, is inclined at an angle 5 of at most 12° relative to the longitudinal axis A of the collimator 100.
[0047] The recess has an end face 20 that connects the first partial surface 191 with the second partial surface 192, the end face 20 being such that, during normal use of the collimator 100, the end face 20 of the recess 17 is outside all light paths 231, 232, 233 (Fig. 1a). In the illustrated embodiment, the end face 20 is inclined at an angle y of 90° relative to the longitudinal axis A of the collimator 100.
[0048] The truncated sections 181, 182 are designed as truncated cones with a circular cross-section, and the light-entry surface 101 of the collimator 100 is scaled smaller than the base 13 of the truncated section 12. In the illustrated embodiment, the convex light-emission surface 102 is approximately spherical with a variable curvature. This means that the light-emission surface 102 is semi-spherical or cap-shaped along a radius R, with the longitudinal axis A of the collimator 100 intersecting the center point M. A retaining rim 21 is formed between the light-emission surface 102 and the truncated section 12, spaced axially and radially from the base 13 of the truncated section 12.
[0049] In the context of two specific embodiments of collimators 100 made of PMMA, these have the following specific dimensions in combination with the light source 15:
[0050] Fig. lc shows a detailed view of the collimator 100 in the area of the first partial stump 181 with the first partial cladding surface 191. In the illustrated embodiment, the light entry surface 101 has a light-scattering structure 22 over its entire surface in the form of concave microlenses 221.
[0051] Fig. 2 shows the collimator 100 according to Fig. 1 with the light paths 231, 232, 233 indicated, which extend from the light entry surface 101 to the light exit surface 102 through the collimator 100. The reflection surface 103, which is formed sectionally by the first partial surface 191 and sectionally by the second partial surface 192, results in at least three different light paths 231, 232, 233 within the collimator 100. In a first light path 231, the light from the light source 15 couples into the light entry surface 101 and is refracted, if at all, to such an extent that the light couples out directly at the light exit surface 102. In contrast, a second light path 232 couples in at the light entry surface 101 and is refracted in such a way that the light path 232 is reflected at the second partial surface 192 and then couples out at the light exit surface 102.The recess 17 and the partial surface 191 create a third light path 233, in which light coupling at the light-entry surface 101 undergoes a first reflection at the first partial surface 191 and a second reflection at the second partial surface 192 before coupling out at the light-emission surface 102. Because the light source 15 is extended, the light paths 231, 232, 233 depend not only on the emission angle but also on the location on the surface of the light source 15. This means that all three light paths 231, 232, 233 can occur even with the same emission angle but different emission locations on the surface of the light source 15. Fig. 3 shows an alternative embodiment of the collimator 100, which differs from the embodiment according to Figs. 1a, 1b, and 2 essentially in the design of the end face 20 of the recess 17.In the illustrated embodiment, the end face 20 of the recess is inclined at an angle y of 45° relative to the longitudinal axis A of the collimator 100. Regardless of this, the end face 20 is not an optical surface 10.
[0052] Fig. 4 shows an alternative embodiment of the collimator 100, which differs from the embodiments according to Figs. 1a, 1b, 2 and 3 essentially in the design of the end face 20 of the recess 17. In the illustrated embodiment, the end face 20 of the recess is convexly round. Regardless of this, the end face 20 is not an optical surface 10.
[0053] Fig. 5 shows a lamp 200 in the form of a headlamp 24. The headlamp 24 has a lamp head 25 with a housing 26, which includes a front panel TI with a first collimator 100 and a second collimator 28. The first collimator 100 corresponds to the collimator 100 from Figs. 1a, 1b, and 2. The second collimator 28 is designed as a TIR collimator 281 and is designed for narrow beam angles. In the illustrated embodiment, the collimators 100 and 28 are integrally connected to the front panel TI. Each of the collimators 100 and 28 is associated with a light source 15. The housing 26 of the headlamp 24 is connected to a headband 29, which, when the headlamp 24 is used as intended, is designed to hold the headlamp 24 against the forehead of the user.Inside the housing 26 are arranged electronic components 30, in particular an unnumbered battery, for controlling and supplying power to the headlamp 24.
[0054] Reference symbol list
[0055] Collimator luminaire optical surface light entry surface light exit surface reflection surface lateral surface blunt base surface partial base surface top surface partial top surface light source air gap recess partial blunt partial blunt partial lateral surface partial lateral surface end surface mounting edge light-diffusing structure concave microlens light path light path light path headlamp luminaire head housing front panel collimator TIR collimator 29 headband
[0056] 30 electronic components
[0057] 3111 Circumference line
[0058] 3112 Circumference line
[0059] 3121 Circumference line
[0060] 3122 Circumference line
[0061] A Longitudinal axis a Angle β Angle
[0062] Y angle
[0063] 5 angles
[0064] M Center
[0065] S secant
[0066] T tangent
Claims
Claims 1. Collimator (100) for collimating light by means of several optical surfaces (10), each forming optical interfaces with a change in optical density, wherein the collimator (100) extends along a longitudinal axis (A) and the optical surfaces (10) comprise a light-entry surface (101), a light-emission surface (102) and a reflection surface (103), wherein the reflection surface (103) is designed as a lateral surface of a truncated form (12) having a base (13) and a top surface (14), wherein the base (13) faces the light-emission surface (102) and the top surface (14) coincides at least partially with the light-entry surface (101), characterized in that the truncated form (12) has an annular recess (17) surrounding the light-entry surface (101).such that the stump (12) has a first partial stump (181) with a first partial lateral surface (191) and a second partial stump (182) with a second partial lateral surface (192), wherein the partial lateral surfaces (191, 192) form the reflection surface (103) and are spaced axially and radially apart from each other.
2. Collimator (100) according to claim 1, characterized in that the stump (12) has a single annular recess (17).
3. Collimator (100) according to one of claims 1 or 2, characterized in that the first partial truncated section (181) has a first partial base surface (131) and a first partial top surface (141), each of which is bounded by a circumferential line (3111, 3112), wherein each secant (S) which a) intersects the circumferential line (3112) of the first partial base surface (131) and the circumferential line (3111) of the first partial top surface (141) and b) extends within an axial plane and c) does not intersect the longitudinal axis (A) in a section between the first partial base surface (131) and the first partial top surface (141) is inclined at an angle (a) to the longitudinal axis (A) of the collimator (100), wherein a is in particular: 0 < a < 8°, preferably 0 < a < 6°.
4. Collimator (100) according to one of claims 1 to 3, characterized in that the second partial truncated section (182) has a second partial base surface (132) and a second partial top surface (142), each of which is bounded by a circumferential line (3121, 3122), wherein each secant (S) which a) intersects the circumferential line (3122) of the second partial base surface (132) and the circumferential line (3121) of the second partial top surface (142) and b) extends within an axial plane and c) does not intersect the longitudinal axis (A) in a section between the second partial base surface (132) and the second partial top surface (142) is inclined at an angle (β) to the longitudinal axis (A) of the collimator (100), wherein β is in particular: 0 < β < 7°, preferably 0 < β < 5°.
5. Collimator (100) according to one of claims 1 to 4, characterized in that each tangent (T) of the first partial lateral surface (191) and / or each tangent (T) of the second partial lateral surface (192), which runs within an axial plane, is inclined at an angle (5) to the longitudinal axis (A) of the collimator (100), wherein for 5: 0 < 5 < 12°, preferably 0 < 5 < 10°.
6. Collimator (100) according to one of claims 1 to 5, characterized in that the recess (17) has an end face (20) which connects the first partial surface (191) with the second partial surface (192), wherein the end face (20) preferably extends such that the end face (20) of the recess (17) is outside all light paths (231, 232, 233) when the collimator (100) is used as intended.
7. Collimator (100) according to claim 6, characterized in that the end face (20) is inclined by an average angle y relative to the longitudinal axis (A) of the collimator (100), wherein the angle y is preferably: 45° < y < 90°.
8. Collimator (100) according to one of claims 1 to 7, characterized in that the partial truncations (181, 182) are designed as a truncated cone with a circular cross-section, as a truncated pyramid with a polygonal cross-section or as a truncated elliptical cone with an elliptical cross-section.
9. Collimator (100) according to one of claims 1 to 8, characterized in that the light entry surface (101) of the collimator (100) is scaled smaller than the base surface (13) of the stump (12).
10. Collimator (100) according to one of claims 1 to 9, characterized in that the light entry surface is flat and / or the light exit surface (102) is convex, in particular spherical.
11. Collimator (100) according to one of claims 1 to 10, characterized in that a retaining edge (21) is formed between the light emission surface (102) and the stump (12), wherein the retaining edge (21) is spaced axially and radially from the base surface (13) of the stump (12).
12. Collimator (100) according to one of claims 1 to 11, characterized in that all optical surfaces (10) or a subset thereof have at least partially or completely a light-scattering structure (22), wherein the light-scattering structure (22) preferably comprises concave and / or convex microlenses (221) and / or roughnesses in the case of refractive optical surfaces (10) and preferably concave and / or convex microlenses (221) in the case of reflective optical surfaces (10).
13. Collimator (100) according to one of claims 1 to 12, characterized in that the ratio of the height (h2) of the second partial truncation (182) and the height hh (hi) of the first part of the stump (181) the following holds: 15 < — < 60, in particular 20 < — < 50.
14. Lamp (200), in particular a flashlight or headlamp (24), with a lamp head (25) having at least one collimator (100) and a light source (15) which is oriented such that its emitted light is directed towards a light entry surface (101) of the collimator (100) during intended use, characterized in that the collimator (100) is designed according to one of claims 1 to 13.