Collimator and portable lighting device

Abstract

A collimator (1) for collimating light uses a plurality of optical surfaces each forming optical boundary surfaces with a change in the optical density. The collimator (1) has a substantially flat light entry surface (2), a convex light exit surface (4) and a totally reflective side wall (3) connecting the light entry surface (2) to the light exit surface (4). A portable lighting device is provided having such a collimator. In order to provide a collimator and a portable lighting device having a collimator which achieves a better light distribution, the light exit surface of the collimator has light-refracting structures (5).

Claims

1. A collimator for collimating light by means of a plurality of optical surfaces each forming optical boundary surfaces with a change in optical density, the collimator comprising: only one light entry surface, the only one light entry surface being completely flat; a convex light exit surface; a totally reflective side wall connecting the only one light entry surface to the light exit surface, wherein the light exit surface comprises light-refracting structures, wherein the light-refracting structures are configured as concave and/or convex microlenses; and a retaining edge surrounding the light exit surface.

2. The collimator according to claim 1, wherein the microlenses are of spherical or aspherical configuration and are arranged on the light exit surface of the collimator as a square, a hexagon, annularly or phyllotactically.

3. The collimator according to claim 1, wherein the microlenses comprise a spherical microlens that has a radius of curvature of 0.4 mm to 6 mm.

4. The collimator according to claim 3 wherein the radius of curvature is 0.75 mm to 3 mm.

5. The collimator according to claim 3 wherein the radius of curvature is 1 mm to 2 mm.

6. The collimator according to claim 1, wherein the only one light entry surface has a polygonal, square or round cross-section.

7. The collimator according to claim 1, wherein in cross-section the side wall is at least in sections of concave, convex or flat configuration, wherein the side wall having a concave configuration in cross-section is of spherical, aspherical, hyperbolic, parabolic, elliptical or Cartesian-oval shaped configuration, wherein a cross-sectional plane contains the optical axis of the collimator.

8. The collimator according to claim 1, wherein the light exit surface has a spherical or aspherical curvature and is of round, polygonal or square configuration in cross-section.

9. The collimator according to claim 8, wherein the light exit surface comprises a spherical light exit surface that has a radius of curvature of 4 mm to 20 mm.

10. The collimator according to claim 1, wherein: all of the light-refracting structures are arranged to form a convex curve.

11. The collimator according to claim 1, wherein the collimator is comprised of polycarbonate, polymethyl methacrylate, glass, cyclo-olefin copolymer, cyclo-olefin polymer, polymethacrylmethylimide, or silicone.

12. The collimator according to claim 1, wherein: all of the light-refracting structures are arranged to form one of a spherical and an aspherical arrangement.

13. The collimator according to claim 1, wherein: a center of the only one light entry surface is aligned with a center of the light exit surface in a direction perpendicular to the only one light entry surface.

14. The collimator according to claim 1, wherein: the light-refracting structures are configured as concave microlenses of a spherical design.

15. The collimator according to claim 14, wherein: the concave microlenses are arranged as a square, hexagonal, annular or phyllotaxic shape on the convex light exit surface.

16. The collimator according to claim 1, wherein: the concave and/or convex microlenses are arranged as a hexagonal, annular or phyllotaxic shape on the convex light exit surface.

17. A portable lighting device comprising: a light source; and a collimator having only one light entry surface, the only one light entry surface being completely flat; a convex light exit surface; and a totally reflective side wall connecting the only one light entry surface to the light exit surface, wherein the light exit surface comprises light-refracting structures, wherein the light-refracting structures are configured as concave and/or convex microlenses; a retaining edge surrounding the light exit surface.

18. A portable lighting device according to claim 17, wherein a distance is present between the light source and the only one light entry surface of the collimator.

19. A portable lighting device according to claim 17, wherein a geometry of the light source is adapted to a geometry of the only one light entry surface that the light source with a square cross-section is assigned the only one light entry surface with a square cross-section, or the light source with a round cross-section is assigned the only one light entry surface with a round cross-section, or the light source with a polygonal cross-section is assigned the light source with a corresponding polygonal cross-section.

20. The portable lighting device according to claim 17, wherein the light source comprises one or more light source elements which have a flat light exit surface.

21. The collimator according to claim 17, wherein: the convex light exit surface has edges at the end of a curve of the convex light exit surface, the edges of the curve extend beyond an imaginary tangential extension of the side wall.

22. A collimator for collimating light by means of a plurality of optical surfaces each forming optical boundary surfaces with a change in optical density, the collimator comprising: only one light entry surface, the only one light entry surface being completely flat; a convex light exit surface; and a totally reflective side wall connecting the only one light entry surface to the light exit surface, wherein the light exit surface comprises light-refracting structures, wherein the light-refracting structures are configured as concave and/or convex microlenses; the side wall is adapted to have an imaginary tangential extension of the side wall intersect the light exit surface, so that a positive angle is formed between the imaginary tangential extension of the side wall and a direct linear connection of edges of the light exit surface and the side wall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a cross-sectional view of a first collimator;

(3) FIG. 2 is a cross-sectional view of a second collimator;

(4) FIG. 3 and FIG. 4 are perspective illustrations of two collimators;

(5) FIG. 5 is a view of different arrangements of microlenses; and

(6) FIG. 6 is a view showing a portable lighting device having a collimator.

DESCRIPTION OF PREFERRED EMBODIMENTS

(7) Referring to the drawings, FIG. 1 shows a first specific embodiment of a collimator 1 according to the invention in a cross-section. The collimator 1 has a completely flat and square light entry surface 2 with a width B.sub.1 of 8.41 mm. The light entry surface 2 transitions directly into a cross-sectionally square light guide section with a side wall 3, which in the illustrated exemplary embodiment has a lower region 31 with a concave curvature and an upper region 32 with a convex curvature. Between the concave (lower) region 31 and the convex (upper) region 32 of the side wall 3, inflection points 33 are formed along the circumferential line at which a tangent applied to the side wall 3 changes sides. The collimator 1 has a convexly-spherical light exit surface 4 whose envelope (shown in dashed lines) has a radius of curvature R.sub.1 of 16.5 mm. Convex microlenses 5 with a radius of curvature R.sub.2 of 3.0 mm are arranged over the entire area of the light exit surface 4. The light exit surface 4 is surrounded, at least in sections, by a retaining edge 7, which has a thickness d of 1.96 mm and a diameter D.sub.1 of 20 mm. The light exit surface 4 has a diameter D.sub.2 of 14.1 mm at the transition to the retaining edge 7. At the transition between the light guide section with the side wall 3 and the retaining edge 7, the collimator 1 has a width B.sub.2 of 14.0 mm. The total height H of the collimator 1 is 20.22 mm. The collimator 1 is assigned two light source elements 61, 62, which together form a light source 6 and which are arranged at a slight distance from the light entry surface 2 in such a way that the light emitted by the light source elements 61, 62 couples almost completely into the collimator 1.

(8) FIG. 2 shows a second specific embodiment of a collimator 1 according to the invention in a cross-section. The collimator 1 has a completely flat and square light entry surface 2 with a width B.sub.1 of 2.64 mm. The light entry surface 2 transitions into a light guide section with a side wall 3, which in the illustrated exemplary embodiment is of completely concave design. In the illustrated exemplary embodiment, the radius of curvature of the side wall 3 is not constant and has a comparatively small radius of curvature in the lower region of the side wall 3, which becomes steadily larger towards the top, i.e., towards the light exit surface 4. The collimator 1 has a convex spherical light exit surface 4, the envelope (shown in dashed lines) of which has a radius of curvature R.sub.1 of 4.95 mm. Convex microlenses 5 with a radius of curvature R.sub.2 of 1.42 mm are arranged over the entire area of the light exit surface 4. The light exit surface 2 is surrounded, at least in sections, by a retaining edge 7, which has a thickness d of 0.91 mm and a diameter D.sub.1 of 10.9 mm. The light exit surface 4 has a diameter D.sub.2 of 8.14 mm at the transition to the retaining edge 7. At the transition between the light guide section with the side wall 3 and the retaining edge 7, the collimator 1 has a width B.sub.2 of 5.22 mm. The total height H of the collimator 1 is 7.71 mm. The collimator is assigned 1 a light source 6, which is arranged at a slight distance from the light entry surface 2 in such a way that the light emitted by the light source 6 couples almost completely into the collimator 1.

(9) In particular in the collimator 1 according to FIG. 2, an imaginary tangential extension 11 of the side wall 3 intersects the light exit surface 4. This means that a positive angle is formed between the imaginary tangential extension 11 of the side wall 3 and a direct linear connection 12 of the edges of the light exit surface 4 and the side wall 3. In the embodiment shown, the angle is 40.1. This advantageously reduces potential losses of light output power.

(10) FIG. 3 shows a further embodiment of a collimator 1 according to the invention in a perspective view. The collimator 1 has a square light entry surface 2 andin a top viewa likewise square light exit surface 4, which, however, outwardly forms a convexly spherical light exit surface 4 with microlenses 5 arranged thereon covering the entire surface. The light entry surface 2 transitions into a light guide section with the side wall 3. A retaining edge 7 is arranged on two opposite sides of the collimator 1, so that the retaining edge 7 surrounds the collimator 1 only in areas.

(11) FIG. 4 shows a further embodiment of a collimator 1 according to the invention with a square light entry surface 2 and a light exit surface 4 of circular cross-section, which is completely surrounded by an annular retaining edge 7. The light entry surface 2 transitions into a light guide section with the side wall 3. The light exit surface 4 is also of convexly-spherical design and has convex microlenses 5 covering the entire surface.

(12) The microlenses 5 can be arranged in different ways on the light exit surface 4 of a collimator 1. FIGS. 5a, b, c and d show different and preferred arrangements of the microlenses 5, which can be adapted to the geometry of the collimator and to the intended light distribution as required. FIG. 5a shows a squared arrangement of microlenses 5. FIG. 5b shows a hexagonal arrangement of microlenses 5. FIG. 5c is shows an annular arrangement of microlenses 5 and finally FIG. 5d discloses a phyllotaxic arrangement of microlenses 5.

(13) A collimator 1 of the type described above is used in the context of a specific embodiment of the invention as a collimator 1 for a portable lighting device 8, in particular a flashlight 81. FIG. 6 shows in schematic view a cross-sectional view of a flashlight 81 with a collimator 1, a light source 6, a housing 9 and a power supply mounted therein in the form of a battery 10. The battery 10 is connected to control electronics (not shown) using which the instantaneous light output of the light source 6 can be controlled automatically or manually.

(14) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

REFERENCE CHARACTERS

(15) 1 collimator 2 light entry surface 3 side wall 31 lower region 32 upper region 33 inflection point 4 light exit surface 5 microlens 6 light source 61 light source element 62 light source element 7 retaining edge 8 lighting device 81 flashlight 9 housing 10 battery 11 tangential extension of the side wall 12 linear connection angle B.sub.1 width of light entry surface B.sub.2 width of side wall at the transition to the retaining edge d thickness of retaining edge D.sub.1 diameter of retaining edge D.sub.2 diameter of light exit surface H height of the collimator R.sub.1 radius of curvature of light exit surface R.sub.2 radius of curvature of microlens