Precollimator for a lighting device

Abstract

The disclosure describes a precollimator for a lighting device, including: a) a number of first collimator units each having an entry face and an exit plane, wherein for each first collimator unit the exit plane is wider than the entry face in a first direction and the entry face and the exit plane have the same width in a second direction that is perpendicular to the first direction and b) a second collimator unit having an entry plane and an exit face, wherein the exit face is wider than the entry plane in the second direction, and
wherein the exit plane of each first collimator unit is optically connected to the entry plane of the second collimator unit, wherein the precollimator is joined together from at least two components. The disclosure further describes such lighting device and a method to manufacture such precollimator.

Claims

1. A precollimator for a lighting device, comprising: a plurality of first collimator units, each first collimator unit comprising an entry face and an exit plane, the exit plane of each first collimator unit being wider than the entry face of the first collimator unit in a first direction, the entry face and the exit plane of each first collimator unit having the same width in a second direction perpendicular to the first direction; and a second collimator unit having an entry plane and an exit face, the exit face of the second collimator unit being wider than the entry plane of the second collimator unit in the second direction, the exit plane of each first collimator unit optically connected, with no gap in-between, to the entry plane of the second collimator unit.

2. The precollimator according to claim 1, wherein the exit face and the entry plane of the second collimator unit have the same width in the first direction, wherein two opposite side faces of the second collimator unit are preferably parallel to each other and arranged perpendicular to the first direction.

3. The precollimator according to claim 1, wherein two opposite side faces of each of the first collimator units are parallel to each other and arranged perpendicular to the second direction.

4. The precollimator according to claim 1, wherein the first collimator units comprise silicone sheet or glass and are cut out of a transparent plate of material.

5. The precollimator according to claim 1, wherein the exit planes of at least two first collimator units have different dimensions, wherein the widths of these exit planes in the first direction are different.

6. The precollimator according to claim 1, wherein a surface of the exit face of the second collimator unit is provided with a texture or an optical structure, wherein this surface of the exit face comprises a lens structure, wherein the lens structure is designed to optically shift the exit face of the second collimator unit in the direction of the entry plane of the second collimator unit to the position of the entry plane of the second collimator unit.

7. The precollimator according to claim 1, wherein the first collimator units are arranged in the first direction, wherein the exit planes of two or more first collimator units are optically connected to a transparent junction element.

8. The precollimator according to claim 7, wherein the second collimator unit comprises the junction element and a collimating segment optically connected to the junction element, wherein the collimating segment comprises a groove designed such that the junction element fits in that groove or is arranged on the junction element in the second direction.

9. The precollimator according to claim 1, wherein the first collimator units have the shape of a geometrical extrusion body of an area extruded along the second direction, and wherein the second collimator unit has the shape of a geometrical extrusion body of an area extruded along the first direction.

10. The precollimator according to claim 1, wherein the second collimator unit and the first collimator units are made of optical glass, wherein the connection between the second collimator unit with the exit planes of the first collimator units is achieved by heat fusion.

11. The precollimator according to claim 1, wherein the second collimator unit is at least in the region of its entry plane by an additional width wider than the sum of the widths of the exit planes of the first collimator units in the first direction, wherein the additional width is designed for mounting the precollimator within the lighting device.

12. A lighting device comprising the precollimator according to claim 1, and a plurality of light sources, each light source arranged to emit light into the entry face of a corresponding one of the first collimator units.

13. The lighting device according to claim 12, comprising a projection optic designed such that it has different focal planes in the first direction and the second direction, wherein the projection optic is designed and arranged such that the focal plane in the first direction lies at the position of the entry plane of the second collimator unit and the focal plane in the second direction lies at the position of the exit face of the second collimator unit.

14. A method for producing the precollimator according to claim 1, comprising the steps: producing or providing the plurality of first collimator units producing or providing the second collimator unit, and joining the plurality of first collimator units to the second collimator unit so that the exit plane of each first collimator unit is optically connected to the entry plane of the second collimator unit.

15. The method according to claim 14, wherein each first collimator unit or the second collimator unit has the shape of a geometric extrusion body, the first collimator units are cut from a plate, and the second collimator is produced as an extrusion element, and the exit planes of the first collimator units are optically connected with the entry plane of the second collimator unit.

16. The method according to claim 14, wherein the first collimator units are cut from a plate in one piece connected to a junction element, a collimating section of the second collimator is produced as extrusion element and is optically joined with the junction element, the collimating section comprises a groove, and the junction element is optically joined into the groove of the collimating section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a perspective view of an embodiment of the inventive lighting device;

(2) FIG. 2 shows a perspective view of an embodiment of the inventive precollimator;

(3) FIG. 3 shows a perspective view of another embodiment of the inventive precollimator;

(4) FIG. 4 shows a perspective view of another embodiment of the inventive precollimator;

(5) FIGS. 5A and 5B show a side view of a further embodiment of the inventive lighting device, and FIG. 5B shows a magnified portion of FIG. 5A;

(6) FIG. 6 shows a perspective view of a preferred directional lighting unit.

(7) In the drawings, like numbers refer to like objects throughout. Objects in the diagrams are not necessarily drawn to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(8) FIG. 1 shows a perspective view of an embodiment of the inventive lighting device L comprising three light sources 3, e.g. LEDs, a precollimator P according to the invention and a projection optic 4 in form of an astigmatic lens with two focal planes P1 and P2. In reality, the distance of the projection optic 4 to the precollimator P could be much greater than shown in the figure. For example, the precollimator P could have a dimension of 25 mm30 mm in the x-z-plane and the projection optic could be arranged 50 to 60 mm distant to the precollimator P and could have a diameter of about 40 to 50 mm.

(9) The precollimator P comprises three first collimator units 1. The exit faces 1b of these first collimator units 1 are optically (and here also mechanically) connected to the entry face 2a of the second collimator unit 2.

(10) The entry faces 1a of the first collimator units 1 are as high as the exit faces 1b of the first collimator units 1 in a second direction y (here the direction of the y-axis), but the entry faces 1a are narrower than these exit faces 1b in a first direction x (here the direction of the x-axis) perpendicular to the second direction y.

(11) FIG. 2 shows a perspective view of an embodiment of a precollimator P according to the invention. The shape of the precollimator P is similar to the precollimator P of the lighting device L shown in FIG. 1, however, with some differences. One difference is that here also mounting structures 5a, 5b, 5c are shown for mounting the precollimator P. Another difference between the precollimators P of FIGS. 1 and 2 is that here the exit faces 1b of the first collimator units 1 have different dimensions in the first direction x (along the x-axis): following the x-axis, the first exit face 1b is the widest followed by the smallest exit face 1b again followed by an exit face 1b of intermediate width of the first collimator units 1.

(12) The upper and lower side faces 1c of the first collimator units 1 are parallel to each other so that the first collimator units 1 form geometrical extrusion bodies of the shape of the upper side faces 1c. The first collimator units 1 are mounted in the region of their entry faces 1a (see FIG. 1) with a first mounting structure 5a.

(13) Similar to the upper and lower side faces 1c of the first collimator units 1, the left and right side faces 2c of the second collimator unit 2 are also parallel to each other, however, this is not necessary. Different from FIG. 1, the second collimator unit 2 is wider than the sum of the widths of the exit faces 1b of the three first collimator units 1 in order to apply two mounting structures 5b for mounting the region where there is a contact between the exit faces 1b of the first collimator units 1 with the entry face 2a of the second collimator unit 2. The exit face of the second collimator unit 2 is mounted with the help of a further mounting structure 5c.

(14) In the state of the art, a collimator light guide has typically collimating properties in both the first direction x (here horizontal) and the second direction y (here vertical). The collimation (i.e. a reduction of the numerical aperture) depends on the ratio of the output and input dimensions. It could be seen, due to the shapes of the first collimator units and the second collimator unit, that the collimation is achieved horizontally and vertically in two steps. The first collimator, which is plano-parallel in the second direction y (uniform height) collimates only in the (horizontal) first direction x, narrowing the beam by a factor A(entry)/A(exit), where A(entry) is the area of the entry face 1a and A(exit) is the area of the exit face 1b of the first collimator units 1. Since the three first collimators 1 have different output widths in the first direction x and the same dimension in the second direction y, they collimate horizontally by different amounts and provide, at their output, three pixels of different horizontal width. Their shape in the x-z-plane, here simply trapezoids, can be more complex in order to not only collimate, but also to bend the output beam horizontally into a certain direction. Then, the following second collimator unit 2 collimates only in the second direction y, again by a factor of B(entry)/B(exit), wherein here B(entry) is the area of the entry face 2a and B(exit) is the area of the exit face 2b of the second collimator unit.

(15) FIG. 3 shows a perspective view of another embodiment of a precollimator P according to the invention. The shape of the precollimator P is similar to the precollimator P of the lighting device L shown in FIG. 1, with the difference that the first collimator units 1 are assembled in one piece together with a junction element 6.

(16) Since, conceptually, the junction element 6 belongs to the second collimator unit 2, one face of the junction element 6 could be addressed as entry plane 2a of the second collimator unit 2. Although there is no contact region of the exit planes 1b of the first collimator units 1 and the entry plane 2a of the second collimator unit 2, the dash dotted line shows that there could always be assumed a theoretical region where the first collimator units 1 meet the second collimator unit 2, although this body is manufactured as one piece. This piece has the shape of an extrusion body of an area in the x-z-plane extruded into the y-direction.

(17) The second collimator unit comprises the junction element 6 and additionally a collimating segment 7 that is optically (and mechanically) connected to the junction element 6. FIG. 3 shows the junction element 6 and the collimating segment 7 with a groove 7a spaced a little apart. These parts could easily be shifted into another. The junction element 6 is designed such that it fits in that groove 7a of the collimating segment 7 forming a locking fit.

(18) FIG. 4 shows a perspective view of another embodiment of a precollimator according to the invention as an alternative to FIG. 3. Here, two collimating segments 7 are arranged over and under the junction element 6 in the second direction y. The junction element 6 ranges from the entry plane 2a of the second collimator unit 2 to its exit face 2b. The front faces of junction element 6 and the two collimating segments 7 are flush fitting and form the flat exit face 2b of the second collimator unit 2 when arranged on one another. Here, the collimating segments 7 are shaped as triangular prisms with one leg of the triangle reaching from the entry plane 2a to the exit face 2b of the second collimator unit 2.

(19) FIG. 5 shows a side view of a further embodiment of the inventive lighting device L. In this example, the lighting device L comprises a projection optic 4, a light source 3, and a precollimator. The setup could be similar to that shown in FIG. 1. In this figure, two focal planes P1, P2 of the projection optic 4 are shown. The projection optic is designed and arranged such that the first focal plane P1 is positioned at the entry face 2a of the second collimator unit 2 and the second focal plane P2 is positioned at the exit face 2b of the second collimator unit 2.

(20) In this figure, three exemplary light rays are shown in the precollimator. All light rays pass the first collimator unit 1 without reflection, and two of these light rays are reflected by the second collimator unit 2.

(21) In this example, the surface of the exit-face 2b of the second collimator unit 2 is structured with a lenticular lens array 8 that can be seen in the enlarged section below. The structure of the lenticular lens array 8 is designed such that light is spread in the dimension perpendicular to the LED row (in the y direction in the y-z-plane) indicated by the three light rays in the enlarged section.

(22) FIG. 6 shows a perspective view of a preferred (directional) lighting device L in a headlight 9 of a car. The lighting device L comprises in this example three precollimators P that are shown from front view. Each precollimator is assigned to an individual row of LEDs (not shown, see e.g. FIG. 1) arranged at the different entry faces of the first collimating units 1 (not shown, see e.g. FIG. 1) optically joined with three second collimator units 2 arranged over one another. In front of the three rows of second collimator units 2, a projection optic 4 is arranged.

(23) Although the present invention has been disclosed in the form of preferred embodiments and variations thereof, it is to be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(24) For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements. The mention of a unit or a module does not preclude the use of more than one unit or module. Especially, the mention of a unit or a module does not preclude that the unit or module could be constructed from more than one piece or could comprise a part of a piece (e.g. the junction part).

REFERENCE SIGNS

(25) 1 first collimator unit 1a entry face 1b exit plane/exit face 1c side face 2 second collimator unit 2a entry plane/entry face 2b exit face 2c side face 3 light source 4 imaging optic 5a mounting structure 5b mounting structure 5c mounting structure 6 junction element 7 collimating segment 7a groove 8 lenticular lens array 9 headlight P precollimator L lighting device P1, P2 focal planes x first direction/coordinate axis y second direction/coordinate axis z third direction/coordinate axis