Light source arrangement in a pixel-light light module

Abstract

The invention relates to a lighting device (20, 30) for a headlight, in particular a motor-vehicle headlight, comprising a plurality of light sources (200, 300), which are arranged adjacent to each other in rows (201, 202, 203, 301, 302, 303) and which form a lighting field (209, 309), and comprising a light-guiding device (204, 304) having a plurality of light-guiding elements (201a, 202a, 203a, 301a, 302a, 303a), wherein each light-guiding element (201a, 202a, 203a, 301a, 302a, 303a) is associated with one light source (200, 300), wherein each light-guiding element (201a, 202a, 203a, 301a, 302a, 303a) has a light incoupling surface (201b, 202b, 203b, 301b, 302b, 303b) for coupling in light emitted by the particular light source and a light outlet surface, wherein the light-guiding elements (201a, 202a, 203a, 301a, 302a, 303a) are arranged in at least two linear rows (211, 212, 213, 311, 312, 313) arranged one over the other, and wherein the light-guiding elements (203a, 303a) of the lowest row (213, 313) are designed as high-beam light-guiding elements (201a, 301a) and form a high-beam row (213, 313), wherein the vertical distance between the light sources (200, 300) of the high-beam row (213, 313) and the light sources (200, 300) of the row (212, 312) arranged adjacent in the upward direction is smaller in at least one lateral edge region (208, 308) of the lighting field (209, 309) than in a central region (207, 307) of the lighting field (209, 309).

Claims

1. A lighting device (20, 30) for a motor-vehicle headlight, comprising: a plurality of light sources (200, 300), which are arranged adjacent to each other in rows (201, 202, 203, 301, 302, 303) and which form a lighting field (209, 309) a light-guiding device (204, 304) having a plurality of light-guiding elements (201a, 202a, 203a, 301a, 302a, 303a), wherein each light-guiding element (201a, 202a, 203a, 301a, 302a, 303a) is associated with one of the light sources (200, 300), wherein each light-guiding element (201a, 202a, 203a, 301a, 302a, 303a) has a light incoupling surface (201b, 202b, 203b, 301b, 302b, 303b) for coupling in light emitted by the particular light source and a light outlet surface, wherein the light-guiding elements (201a, 202a, 203a, 301a, 302a, 303a) are arranged in at least two linear rows (211, 212, 213, 311, 312, 313) arranged one over the other, and wherein the light-guiding elements (203a, 303a) of the lowest row (213, 313) are designed as high-beam light-guiding elements (201a, 301a) and form a high-beam row (213, 313), wherein the vertical distance between the light sources (200, 300) of the high-beam row (213, 313) and the light sources (200, 300) of the row (212, 312) arranged adjacent in the upward direction is smaller in at least one lateral edge region (208, 308) of the lighting field (209, 309) than in a central region (207, 307) of the lighting field (209, 309).

2. The lighting device according to claim 1, wherein the vertical distance between the light sources (200, 300) of the high-beam row (213, 313) and the light sources (200, 300) of the upwardly adjacent row (212, 312) decreases successively starting from the central region (207, 307) in the direction of at least one of the edge regions (208, 308).

3. The lighting device according to claim 1, wherein the vertical distance between the light sources (200, 300) of the high-beam row (213, 313) and the light sources (200, 300) of the upwardly adjacent row (212, 312) in both lateral edge regions (208, 308) of the lighting field (209, 309) is smaller than in the central region (207, 307) of the lighting field (209, 309).

4. The lighting device according to claim 3, wherein the vertical distance between the light sources (200, 300) of the high-beam row (213, 313) and the light sources of the upwardly adjacent row (212, 312) decreases successively starting from the central region (207, 307) in the direction of both edge regions (208, 308).

5. The lighting device according to claim 1, wherein the light sources (200, 300) of the high-beam row (213, 313) which are arranged in the central region (207, 307) of the lighting field (209, 309) are positioned such that they couple in the light in the centre of the light incoupling surface (201b, 301b) of the particular light-guiding element (201a, 301a).

6. The lighting device according to claim 1, wherein the horizontal distance between adjacent light sources (300) increases in at least one of the edge regions (308) of the lighting field (309) in the direction of the row edge.

7. The lighting device according to claim 6, wherein the horizontal distance between adjacent light sources (300) in both edge regions (308) increases in the direction of the row edge.

8. The lighting device according to claim 1, wherein the light sources (200) are arranged symmetrically with respect to an optical axis (210).

9. The lighting device according to claim 1, wherein the light sources (300) are arranged asymmetrically with respect to an optical axis (310).

10. The lighting device according to claim 1, wherein the individual rows (301, 302, 303) of light sources (300) have different lengths.

11. The lighting device according to claim 1, wherein the light-guiding elements (201a, 202a, 203a, 301a, 302a, 303a) are arranged in precisely three rows (211, 212, 213, 311, 312, 313) one above the other and jointly form a high-beam distribution, wherein the lowest row is the high-beam row (213, 313).

12. The lighting device according to claim 1, wherein the light outlet surfaces of the light-guiding elements (201a, 202a, 203a, 301a, 302a, 303a) are part of a common light outlet surface (206, 306), wherein individual light outlet surfaces border on one another.

13. The lighting device according to claim 1, wherein the light sources (200, 300) are light-emitting diodes (LEDs), which can be controlled individually.

14. The lighting device according to claim 1, wherein the light-guiding elements (201a, 202a, 203a, 301a, 302a, 303a) are embodied as optical waveguide elements.

15. The lighting device according to claim 1, further comprising an imaging optics arranged downstream of the light-guiding device (204, 304).

16. The lighting device according to claim 15, wherein the imaging optics comprises one or more optical lenses.

17. A motor-vehicle headlight comprising the lighting device (20, 30) according to claim 1.

Description

(1) The invention and advantages thereof will be explained in greater detail hereinafter on the basis of non-limiting examples, which are shown in the accompanying drawings, in which:

(2) FIG. 1a shows an arrangement of light sources (LEDs) in a pixel-light lighting device according to the prior art,

(3) FIG. 1b shows an arrangement of light sources (LEDs) in a pixel-light lighting device according to the invention,

(4) FIG. 1c shows a further arrangement of light sources (LEDs) in a pixel-light lighting device according to the invention,

(5) FIG. 2 shows a perspective view of a lighting device according to the invention with an arrangement of light sources according to FIG. 1b,

(6) FIG. 3 shows a perspective view of an edge region of a lighting device according to the invention with an arrangement of light sources according to FIG. 1c,

(7) FIG. 4 shows a perspective view of an edge region of a lighting device according to the prior art with an arrangement of light sources according to FIG. 1a.

(8) FIG. 1a shows an arrangement of light sources 100 (LEDs 100) in a pixel-light lighting device 10 according to the prior art. The lighting device 10 is shown in FIG. 4, which shows a perspective view of the edge region thereof. The lighting device 10 comprises a plurality of LED light sources 100 and an add-on optics 104 (=primary optics) positioned in the direction of light emission. The add-on optics 104 comprises optical waveguide elements 101a, 102a, 103a, which are arranged in three linear rows 111, 112, 113 and which run on the emission side to a common end plate 105. The end plate 105 is delimited on the emission side by a light outlet surface 106, wherein the light outlet surfaces (not shown in greater detail) of the individual optical waveguide elements are each part of a common light outlet surface 106, wherein individual light outlet surfaces of the optical waveguide elements 101a, 102a, 103a border on one another in a manner known per se. The common light outlet surface 106 is typically a curved surface, which usually follows the Petzval surface of a downstream imaging optics (not shown in greater detail; for example an imaging lens). For specific applications, deliberate deviations in the curvature of the common light outlet surface 106 can also be used in order to additionally utilise aberrations in the edge region for light homogenisation. Each optical waveguide element 101a, 102a, 103a is assigned an LED light source 100. The light incoupling surfaces 101b, 102b, 103b of the optical waveguide elements 101a, 102a, 103a are larger than the surfaces of the respective light sources 100 (for example chip surface of the LEDs). The light sources 100 are positioned in the lighting device 10 such that they couple the light in the centre of the light incoupling surface 101b, 102b, 103b of the particular optical waveguide element.

(9) In the lighting device 10, the upper row is formed as a forefield row 111 consisting of a plurality of forefield optical waveguide elements 101a. The middle row is formed as an asymmetry row 112 consisting of a plurality of asymmetry optical waveguide elements 102a, and the lower row is formed as a high-beam row 113 consisting of a plurality of high-beam optical waveguide elements 103a. The optical waveguide elements 101a, 102a, 103a are funnel-shaped, wherein the high-beam optical waveguide elements 103a have a larger cross-section in the direction of the light outlet surface than the optical waveguide elements of the asymmetry row 112. For this reason, the pixels of the asymmetry row 112 have a higher illuminance than those of the high-beam row 113.

(10) It can now be seen from FIG. 1a that the light sources 100 of the lighting arrangement 10 are arranged in a 3*28 pixel arrangement in a total of three linear LED rows 101, 102, 103 of 28 LEDs/row and form a lighting field 109. The LEDs 100 are secured on a circuit board in a manner known per se. The light-emitting surfaces are shown in a regular arrangement. The respective vertical distances between the LEDs 100 of the individual rows 101, 102, 103 are always constant, i.e. the LEDs of a row are always arranged at the same vertical distance from the LEDs of an adjacent row. The illumination level can be controlled individually for each LED 100, and therefore any desired light distributions can be provided. With reference to FIG. 1a and FIG. 4, the uppermost LED row 101 couples the light into the optical waveguide elements 101a of the forefield row 111. The middle LED row 102 couples the light into the optical waveguide elements 102a of the asymmetry row 112. The lowest LED row 103 couples the light into the optical waveguide elements 103a of the high-beam row 113. The forefield row 111, the asymmetry row 112, and the high-beam row 113 in the activated state jointly form a high-beam distribution. Usually, the LEDs 100 in a central region 107 are in this case energised more strongly than in the edge regions 108 to the left and right of the central region 107, and therefore the maximum of the light distribution lies in the central region 107. However, the lower energisation in the edge regions 108 can mean that inhomogeneities occur between the rows of the light distribution, typically in the form of dark stripes in the edge regions 108. The inhomogeneities between the high-beam row 113 and the asymmetry row 112 are usually particularly pronounced.

(11) FIG. 1b shows an arrangement of LED light sources 200 in a pixel-light lighting device 20 according to the invention (see also FIG. 2 in this respect). The lighting device 20 is shown in greater detail in FIG. 2, which shows a perspective view of a lighting device 20 according to the invention.

(12) The lighting device 20 comprises a plurality of LED light sources 200 and a light-guiding device 204, referred to hereinafter as an add-on optics 204 (=primary optics), positioned in the direction of light emission. The add-on optics 204 is constructed identically to the add-on optics 104. The add-on optics 204 consequently comprises optical waveguide elements 201a, 202a, 203a, which are arranged in three linear rows 211, 22, 213 and which run on the emission side to a common end plate 205. The end plate 205 is delimited on the emission side by a light outlet surface 206, wherein the light outlet surfaces (not shown in greater detail) of the individual optical waveguide elements 201a, 202a, 203a are each part of the common light outlet surface 206, wherein individual light outlet surfaces of the optical waveguide elements 201a, 202a, 203a border on one another in a manner known per se. The common light outlet surface 206 is typically a curved surface, which usually follows the Petzval surface of a downstream imaging optics (not shown in greater detail; for example an imaging lens). For specific applications, deliberate deviations in the curvature of the common light outlet surface 206 can also be used in order to additionally utilise aberrations in the edge region for light homogenisation. Each optical waveguide element 201a, 202a, 203a of the add-on optics 204 is assigned an LED light source 200. The light incoupling surfaces 201b, 202b, 203b of the optical waveguide elements 201a, 202a, 203a are larger than the surfaces of the respective LED light sources 200 (for example chip surface of the LEDs).

(13) In the lighting device 20, the upper row is formed as a forefield row 211 consisting of a plurality of forefield optical waveguide elements 201a. The middle row is formed as an asymmetry row 212 consisting of a plurality of asymmetry optical waveguide elements 202a, and the lower row is formed as a high-beam row 213 consisting of a plurality of high-beam optical waveguide elements 203a. The optical waveguide elements 201a, 202a, 203a are funnel-shaped, wherein the high-beam optical waveguide elements 203a have a larger cross-section in the direction of the light outlet surface than the optical waveguide elements of the asymmetry row 212. For this reason, the pixels of the asymmetry row 212 have a higher illuminance than those of the high-beam row 213.

(14) It can be seen from FIG. 1b that the light sources 200 of the lighting arrangement 20 are arranged in a 3*28 pixel arrangement in a total of three LED rows 201, 202, 203 of 28 LEDs/row and form a lighting field 209. The LEDs 200 are secured on a circuit board in a manner known per se. The illumination level can be controlled individually for each LED 200, and therefore any desired light distributions can be provided. With reference to FIG. 1b and FIG. 2, the uppermost LED row 201 couples the light into the optical waveguide elements 201a of the forefield row 211. The middle LED row 202 couples the light into the optical waveguide elements 202a of the asymmetry row 212. The lowest LED row 203 couples the light into the optical waveguide elements 203a of the high-beam row 213. The forefield row 211, the asymmetry row 212, and the high-beam row 213 in the activated state jointly form a high-beam distribution. Usually, the LEDs 200 in a central region 207 are in this case energised more strongly than in the edge regions 208 to the left and right of the central region 207, and therefore the maximum of the light distribution lies in the central region 207.

(15) The respective vertical distances between the LEDs 200 of the rows 201 and 202 (assigned to the forefield row 211 and asymmetry row 212) are always constant, i.e. the LEDs of the forefield row 211 are always arranged at the same vertical distance from the LEDs of the asymmetry row 212. The arrangement according to the invention of the LED light sources 200 differs from the arrangement according to the prior art (FIG. 1a) in that the vertical distance between the LED light sources 200 of the high-beam row 212 and the LED light sources 200 of the upwardly adjacent row (i.e. the asymmetry row 212) in the lateral edge regions 208 of the lighting field is smaller than in a central region 207 of the lighting field. In other words, the vertical distance between the light sources 200 of the high-beam row 213 and the light sources 200 of the asymmetry row 212 decreases starting from the central region 207 in the direction of the edge regions 208 of the lighting field 209 successively, i.e. step by step, from LED to LED. The LED light sources 200 are arranged symmetrically with respect to an optical axis. The LED light sources 200 of the LED rows 201 and 202 and the LED light sources 200 in the central region 207 of the LED row 203 are positioned such that they couple in the light in the centre of the light incoupling surface 201b, 202b, 203b of the particular optical waveguide element 201a, 202a, 203a. The LED light sources 200 in the edge regions 208 of the LED row 203 (i.e. assigned to the high-beam row 213) are shifted from the centre of the light incoupling surface 203b of the particular optical waveguide element 203a upwardly in the direction of the LED row 202 (i.e. assigned to the asymmetry row 212) (see also FIG. 2, in which this shift is clearly visible). By means of the selective arrangement according to the invention of the LED light sources 200 in the edge regions 208 of the lighting field 209, the inhomogeneities in the light image, as are known from the prior art, can be reduced. The arrangement according to the invention therefore constitutes a technically simple and economical measure for locally influencing the light distribution in pixel-light lighting devices and thus providing a more homogeneous light distribution in the edge regions 208 of the lighting field 209.

(16) FIG. 1c shows a further variant of an arrangement of light sources (LEDs) 300 in a pixel-light lighting device 30 according to the invention. The lighting device 30 is shown in FIG. 3, which shows a perspective view of the edge region thereof.

(17) The lighting device 30 comprises a plurality of LED light sources 300 and a light-guiding device 304, referred to hereinafter as an add-on optics 304 (=primary optics), positioned in the direction of light emission. The add-on optics 304 comprises optical waveguide elements 301a, 302a, 303a, which are arranged in three linear rows 311, 312, 313 and which run on the emission side to a common end plate 305. The end plate 305 is delimited on the emission side by a light outlet surface 306, wherein the light outlet surfaces (not shown in greater detail) of the individual optical waveguide elements 301a, 302a, 303a are each part of the common light outlet surface 306, wherein individual light outlet surfaces of the optical waveguide elements 301a, 302a, 303a border on one another in a manner known per se. The common light outlet surface 306 is typically a curved surface, which usually follows the Petzval surface of a downstream imaging optics (not shown in greater detail; for example an imaging lens). For specific applications, deliberate deviations in the curvature of the common light outlet surface 306 can also be used in order to additionally utilise aberrations in the edge region for light homogenisation. Each optical waveguide element 301a, 302a, 303a of the add-on optics 304 is assigned an LED light source 300. The light incoupling surfaces 301b, 302b, 303b of the optical waveguide elements 301a, 302a, 303a are larger than the surfaces of the respective LED light sources 300 (for example chip surface of the LEDs).

(18) In the lighting device 30, the upper row is formed as a forefield row 311 consisting of a plurality of forefield optical waveguide elements 301a. The middle row is formed as an asymmetry row 312 consisting of a plurality of asymmetry optical waveguide elements 302a, and the lower row is formed as a high-beam row 313 consisting of a plurality of high-beam optical waveguide elements 303a. The optical waveguide elements 301a, 302a, 303a are funnel-shaped, wherein the high-beam optical waveguide elements 303a have a larger cross-section in the direction of the light outlet surface than the optical waveguide elements of the asymmetry row 312. For this reason, the pixels of the asymmetry row 312 have a higher illuminance than those of the high-beam row 313.

(19) The LED light sources 300 are arranged in a pixel arrangement in a total of three LED rows 301, 302, 303 of 25, 30, and 28 LEDs and form a lighting field 309 (see FIG. 1c). The LEDs 300 are secured to a circuit board (not shown) in a manner known per se. The illumination level can be controlled individually for each LED 300, and therefore any desired light distributions can be provided.

(20) Similarly to the variant according to the invention shown in FIG. 1b and FIG. 2, the uppermost LED row 301 couples the light into the optical waveguide elements 301a of the forefield row 311 of the add-on optics 304. The middle LED row 302 couples the light into the optical waveguide elements 302a of the asymmetry row 312 of the add-on optics 304. The lowest LED row 303 couples the light into the optical waveguide elements 303a of the high-beam row 313 of the add-on optics 304. The forefield row 311, the asymmetry row 312, and the high-beam row 313 jointly form a high-beam distribution in the activated state. Here, the LEDs 300 are energised more heavily in a central region 307 than in the edge regions 308 to the left and right of the central region 307, and therefore the maximum of the light distribution lies in the central region 307.

(21) The vertical distance between the LEDs 300 of the rows 301 and 302 (forefield row and asymmetry row) is always constant (FIG. 1c), i.e. the LEDs 300 of the forefield row are always arranged at the same vertical distance from the LEDs of the asymmetry row. The arrangement according to the invention of the LED light sources 300 from FIG. 1c thus differs from the arrangement according to the prior art (FIG. 1a) in that the vertical distance between the LED light sources 300 of the row 303 (assigned to the high-beam row 313) and the LED light sources 300 of the upwardly adjacent LED row 302 (assigned to the asymmetry row 312) in the lateral edge regions 308 of the lighting field 309 is smaller than in a central region 307 of the lighting field 309. In other words, the vertical distance between the light sources 300 of the high-beam row and the light sources 300 of the asymmetry row decreases starting from the central region 307 in the direction of the edge regions 308 of the lighting field 309 successively. In a development of the arrangement according to the invention shown in FIG. 1b, the horizontal distance between adjacent LED light sources 300 in the edge regions 308 of all three LED rows 301, 302, 303 increases in this embodiment in the direction of the row edge. The individual rows 301, 302 and 303 additionally have different lengths. The LED light sources 300 are arranged asymmetrically with respect to an optical axis 310. In the installed state in a headlight module, the circuit board to which the LED light sources 300 are secured is normally a common part. The circuit board is constructed identically in the left and right motor-vehicle headlight. The add-on optics 30 is provided in mirror-symmetrical variants. An imaging optics provided in the direction of light emission is then again a common part, but is arranged shifted mirror-symmetrically, for example with the aid of a lens holder.

(22) The difference in the construction of the add-on optics 30 compared to the above-described add-on optics 10 and 20 lies in the fact that the optical waveguide elements 301a, 302a, 303a are likewise horizontally shifted accordingly on account of the additional horizontal shifting of the LEDs 300 in the edge regions 308 (see FIG. 3). The LED light sources 300 of the LED rows 301 and 302 and the LED light sources 300 in the central region 307 of the LED row 303 are consequently positioned such that they couple in the light in the centre of the light incoupling surface 301b, 302b, 303b of the particular optical waveguide element 301a, 302a, 303a. The LED light sources 300 in the edge regions 308 of the LED row 303 (i.e. assigned to the high-beam row 313) are shifted in accordance with the invention from the centre of the light incoupling surface 303b of the particular optical waveguide element 303a upwardly in the direction of the adjacent LEDs 300 of the asymmetry row 312.

(23) The optical waveguide elements 201a, 202a, 203a and 301a, 302a, 303a shown in FIGS. 2 and 3 respectively can be manufactured for example from silicone, plastic, glass or any other materials suitable for guiding light. The optical waveguide elements 201a, 202a, 203a and 301a, 302a, 303a are embodied as solid bodies and consist of a single continuous optical medium, wherein the light is guided within this medium.

(24) The LEDs 200 and 300 (FIG. 1b, FIG. 1c) can be, for example, Oslon Compact LEDs with light-emitting surfaces of 0.50.5 mm.sup.2. The total arrangement is approximately 10 cm wide.

(25) The invention can be modified in any way known to a person skilled in the art and is not limited to the presented embodiment. Individual aspects of the invention can also be taken and combined widely with one another. What are essential are the ideas forming the basis of the invention, which can be realised in a variety of ways by a person skilled in the art in view of this teaching but are not modified in essence.