DE102012008930A1 - Device for monitoring function of light sources e.g. LEDs, in light i.e. headlight of vehicle i.e. motor car, has camera detecting function loss of light sources or light power change, and optical element including boundary surface - Google Patents

Abstract

The device (4) has a camera (7) detecting a function loss of light sources (2.1-2.n) or a light power change. An optical element (3) i.e. lens, including a boundary surface is arranged relative to the light sources and the camera such that a predetermined part (T) of a light (L) is directly detected. The light is emitted by the light sources, and strikes the camera. The boundary surface of the optical element is inclined-arranged at the light sources. The camera and light sources are arranged on a carrier element.

Description

The invention relates to a device for monitoring a function of a plurality of light sources arranged in a light source field.

The invention further relates to a luminaire comprising such a device.

From the DE 102 48 238 A1 a lighting device for motor vehicles is known, which comprises a diode array comprising a plurality of light-emitting diodes. Furthermore, the illumination device comprises a diffusing screen, which partially transmits the light emitted by the light-emitting diode arrangement and partially reflects back to the light-emitting diode arrangement. It is one of the light emitting diode array associated control and evaluation provided by means of which the diodes of the light emitting diode array can be controlled such that a respective diode is operated alternately as a light emitting diode and a photodiode. In each phase of operation, one diode as a light emitting diode and one diode as a photodiode is operable in each case, wherein an output signal of each operated as a photodiode diode of the control and evaluation unit can be supplied for evaluation. Based on the evaluation of the output signals monitoring of a function of the diode array is feasible.

Furthermore, devices for monitoring a function of light-emitting diodes as light sources are known from the prior art, wherein a monitoring of the function of the light-emitting diodes is carried out by a current monitoring.

The invention has for its object to provide a comparison with the prior art improved device for monitoring a function of a plurality of arranged in a light source field light sources and a lamp with such a device.

With regard to the device, the object is achieved by the features specified in claim 1 and in terms of the luminaire by the features specified in claim 9.

Advantageous embodiments of the invention are the subject of the dependent claims.

The device for monitoring a function of a plurality of light sources arranged in a light source field comprises according to the invention a camera by means of which a functional failure of at least one of the light sources or a change in luminous flux can be detected.

The camera enables the monitoring of the function in a particularly advantageous manner, even with a high resolution of the light sources, that is, with an increase in a number of light sources per area. In particular, in the case of an embodiment of the light sources as light-emitting diodes, it is possible to monitor several thousand pixels of light-emitting diodes, in particular of more than 5000 pixels. In particular, it is possible with respect to the solution known from the prior art by means of current monitoring, independent of electrical defects of the LEDs and optical defects to detect this. Thus, an optical functional failure of light emitting diodes in electrical functionality of the LEDs is detected. Furthermore, the monitoring by means of the camera makes it possible to detect deviations from a desired state within a particularly short period of time, in particular within a few milliseconds, for the entire arrangement of the light sources.

Thus, when using the device according to the invention in a luminaire, in particular a vehicle headlight, it is possible to monitor light sources designed as light-emitting diodes in a high-resolution light-emitting diode array in a particularly reliable and accurate manner.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 1 is a schematic perspective view of a lighting arrangement according to the prior art;

2 schematically a side view of the lighting arrangement according to 1 .

3 1 is a schematic side view of a lighting arrangement with a first exemplary embodiment of a device according to the invention for monitoring a function of light sources;

4 1 is a schematic side view of a lighting arrangement with a second embodiment of the device according to the invention;

5 FIG. 2 schematically a side view of a lighting arrangement with a third exemplary embodiment of the device according to the invention, FIG.

6 FIG. 2 schematically a side view of a lighting arrangement with a fourth exemplary embodiment of the device according to the invention, FIG.

7 FIG. 2 schematically a side view of a lighting arrangement with a fifth exemplary embodiment of the device according to the invention, FIG.

8th schematically a detection range of a camera of the device according to the invention,

9 schematically a first embodiment of the camera of the device according to the invention and

10 schematically a second embodiment of the camera of the device according to the invention.

Corresponding parts are provided in all figures with the same reference numerals.

In the 1 and 2 is a lighting arrangement 1 represented according to the prior art.

The lighting arrangement 1 is intended for use in a luminaire, not shown. The lamp is for example a vehicle headlight.

The lighting arrangement 1 includes a variety of light sources 2.1 to 2.n , The light sources 2.1 to 2.n are formed as light emitting diodes and arranged in a plurality of rows and a plurality of columns in a in a light source field A or so-called light-emitting diode array, hereinafter referred to as LED array A.

Furthermore, an optical element formed as an optical lens 3 arranged in the emission direction in front of the LED array A. In this case, an optical axis X of the LED array A passes through a center of the optical element 3 , The optical element 3 is intended to produce a defined light distribution, for which purpose by means of the light sources 2.1 to 2.n generated light L deflected, in particular is parallelized.

In an LED array A with a high resolution of the light sources 2.1 to 2.n that is, an LED array A in which a large number of light sources 2.1 to 2.n are arranged on a relatively small area, are functional failures of individual light sources 2.1 to 2.n only insufficiently detectable.

For this reason, the lighting arrangement includes 1 according to 3 a device according to the invention 4 for monitoring a function of a plurality of light sources 2.1 to 2.n ,

The device 4 includes a camera 7 by means of which one at an interface 5.1 a cover 5 the lighting arrangement 1 or in a manner not shown on another separate component reflected part T of the light L is detected. The camera 7 is tilted relative to the LED array A. The reflected part T of the light L generates an in 8th closer illustrated image B of the LED array A on a camera chip, not shown, the camera 7 , one in the 9 or 10 illustrated camera lens 7.1 is not required.

Based on the image of the LED array A on the image B is a function failure of the light sources by means of an evaluation unit, not shown 2.1 to 2.n detected. Alternatively or additionally, a luminous power change is detected.

This is only a low resolution of the camera 7 required. For a reliable and exact monitoring of the light sources 2.1 to 2.n are each light source 2.1 to 2.n approximately 10 Camera pixels required. In an assumed LED array A with 5000 formed as light emitting diodes light sources 2.1 to 2.n Thus, 50000 camera pixels are required, which correspond to a camera resolution of 0.05 megapixels. cameras 7 With such a low resolution are particularly inexpensive and freely available in many designs.

A detection of the on the interface 5.1 the cover 5 pictured image B is for the camera 7 due to a resulting overload at high brightness of the imaged image B not possible. For this reason, it is necessary that only a small part T of the light L from that of the interface 5.1 the cover 5 is reflected.

This is done by means of an inclined arrangement of the interface 5.1 the cover 5 or by means of an inclined arrangement of the entire cover 5 reaches the LED array A, so that the light L is attenuated by the part T and the part T in the direction of the camera 7 is distracted. The reflections of the light L are based on so-called Fresnel reflections at the interface 5.1 the cover 5 ,

The cover 5 is made of glass or plastic. At approximately perpendicular angle of incidence of the light L at the interface 5.1 between air and glass or air and plastic at a refractive index of 1.5 of the medium of the cover 5 About 4% of the light L is reflected. Thus, it is possible by means of the inclined arranged interface 5.1 to attenuate the light L of the LED array A by 4% to 96%, and the 4% portion T of the light L toward the camera 7 distract. The interface 5.1 is formed in particular from a dielectric layer, a metallic layer or a light-absorbing layer.

In the evaluation of the image B by means of the evaluation unit is for detecting the malfunction and / or the luminous power change a from the inclination of the interface 5.1 resulting distortion considered.

4 shows a lighting arrangement 1 with a second embodiment of the device according to the invention 4 , The lighting arrangement 1 is according to the in the 1 and 2 illustrated illumination arrangement 1 educated.

To monitor the function of the light sources 2.1 to 2.n includes the device 4 the camera 7 with a lens 7.1 , where the lens 7.1 according to the 9 or 10 is trained.

By means of the camera 7 becomes one at an interface 3.1 of the optical element 3 reflected part T of the light L detected. The camera 7 is tilted relative to the LED array A. The reflected part T of the light L generates the image B of the LED array A on the camera chip. On the basis of the image B by means of the evaluation unit, the functional failure of the light sources 2.1 to 2.n detected. Alternatively or additionally, the luminous power change is detected. Picture B is characterized by the small distance between the camera 7 and the interface 3.1 by a particularly high image resolution and sharpness, so that in particular at a high resolution of the light sources 2.1 to 2.n a functional failure of individual light sources 2.1 to 2.n and / or the luminous power change can be detected in a simple and reliable manner from the image B or is.

Again, only a low resolution of the camera 7 as in the first embodiment of the device 4 required.

A capture of the on the interface 3.1 pictured image B is for the camera 7 due to a resulting overload at high brightness of the imaged image B not possible. For this reason, it is necessary that only a small part T of the light L from the interface 3.1 is reflected.

This is done by means of an inclined arrangement of the interface 3.1 as in the illustrated second embodiment, or by means of an inclined arrangement of the entire optical element 3 to the LED array A, as in in 5 illustrated third embodiment, achieved. The reflections of the light L are based on Fresnel reflections at the interface 3.1 ,

The optical element 3 is made of glass or plastic. At approximately perpendicular angle of incidence of the light L at the interface 3.1 between air and glass or air and plastic at a refractive index of 1.5 of the medium of the optical element 3 About 4% of the light L is reflected. Thus, it is possible by means of the inclined arranged interface 3.1 to attenuate the light L of the LED array A by 4% to 96%, and the 4% portion T of the light L toward the camera 7 distract. The interface 3.1 is formed in particular from a dielectric layer, a metallic layer or a light-absorbing layer.

During the evaluation of the image B by means of the evaluation unit, one for detecting the functional failure and / or the luminous power change becomes the inclination of the interface 3.1 resulting distortion considered.

5 shows a lighting arrangement 1 with the third embodiment of the device according to the invention 4 to monitor the function of the light sources 2.1 to 2.n , Unlike the in 4 illustrated second embodiment, the entire optical element 3 inclined to the LED array A arranged.

In 6 is the lighting arrangement 1 with a fourth embodiment of the device 4 shown. Unlike the in 3 illustrated first embodiment of the device 4 is the camera 7 arranged not tilted relative to the LED array A, but on a common carrier element 6 with the light sources 2.1 to 2.n arranged. In the carrier element 6 in particular, it is a common circuit carrier, wherein the camera 7 is designed in particular as a camera chip.

7 shows the lighting arrangement 1 with a fifth embodiment of the device according to the invention 4 , Unlike the in 5 illustrated third embodiment, the camera 7 arranged not tilted relative to the LED array A, but on a common carrier element 6 with the light sources 2.1 to 2.n arranged. In the carrier element 6 in particular, it is a common circuit carrier, wherein the camera 7 is designed in particular as a camera chip.

Alternatively to the illustrated tilted arrangement of the entire optical element 3 can only in this embodiment, the interface 3.1 be arranged tilted.

To get a complete picture of the on the interface 3.1 captured image B by means of the camera 7 with the lens 7.1 To realize, either a camera resolution is selected which is greater than the resolution of the LED array A or it becomes a lens 7.1 used, which is based on a so-called shift technology. Such a lens 7.1 is schematic in 10 shown.

In 8th is a detection area E of the camera 7 the device according to the invention 4 shown. This shows the camera 7 a resolution of one megapixel. The image B of the LED array A is made of 5000 light sources 2.1 to 2.n formed and thus has a resolution of 5000 pixels. Because of the compared to the LED array A high resolution of the camera 7 are given all directions of the detection range E tolerances T1 to T4. Due to the tolerances T1 to T4 is a fine adjustment of the camera in a particularly advantageous manner 7 not mandatory. Also, using a shift technology-based lens 7.1 not mandatory.

9 shows a camera 7 with a lens 7.1 in the normal position for detecting an object O. The object O is arranged so that it is within the detection range E of the camera 7 ie that it is fully mapped as picture B on the camera chip.

Shifts the object O relative to the camera 7 , the image B is not reproducible on the camera chip when a defined value of an angle φ is exceeded.

For this purpose, the camera includes 7 according to 10 a lens based on the shift technology 7.1 , which is arranged displaced relative to the camera chip. Thus, even if the defined value of the angle φ is exceeded, the image B can be completely imaged on the camera chip. A relative position of the lens 7.1 to the camera chip is in particular variably adjustable.

All in the previous ones 1 to 10 illustrated lighting arrangements 1 , Devices 4 to monitor the function of the light sources 2.1 to 2.n As well as components of these are intended in particular for use in a luminaire, not shown. The light is, for example, a headlight for a vehicle.

LIST OF REFERENCE NUMBERS

1

lighting arrangement

2.1 to 2.n

light source

3

optical element

3.1

interface

4

contraption

5

cover plate

5.1

interface

6

support element

7

camera

7.1

lens

A

LED array

B

image

e

detection range

L

light

O

object

T

part

T1 to T4

tolerance

X

optical axis angle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10248238 A1 [0003]

Claims (10)

Contraption ( 4 ) for monitoring a function of a plurality of light sources arranged in a light source field (A) ( 2.1 to 2.n ), characterized by a camera ( 7 ), by means of which a functional failure of at least one of the light sources ( 2.1 to 2.n ) or a luminous power change can be detected. Contraption ( 4 ) according to claim 1, characterized in that an optical element ( 3 ) is provided, wherein the optical element ( 3 ) an interface ( 3.1 ) which is so relative to the light sources ( 2.1 to 2.n ) and the camera ( 7 ) is arranged at the interface ( 3.1 ) a predetermined part (T) of the light sources ( 2.1 to 2.n ) emitted light (L) is directionally deflected so that it is on the camera ( 7 ) meets. Contraption ( 4 ) according to claim 2, characterized in that the interface ( 3.1 ) of the optical element ( 3 ) or the optical element ( 3 ) inclined to the light sources ( 2.1 to 2.n ) is arranged. Contraption ( 4 ) according to claim 2 or 3, characterized in that the optical element ( 3 ) is a lens. Contraption ( 4 ) according to one of the preceding claims, characterized in that the camera ( 7 ) and the light sources ( 2.1 to 2.n ) on a common carrier element ( 6 ) are arranged. Contraption ( 4 ) according to one of the preceding claims, characterized in that a cover ( 5 ) a luminaire is provided, wherein the cover ( 5 ) an interface ( 5.1 ) which is so relative to the light sources ( 2.1 to 2.n ) and the camera ( 7 ) is arranged at the interface ( 5.1 ) a predetermined part (T) of the light sources ( 2.1 to 2.n ) emitted light (L) is directionally deflected so that it is on the camera ( 7 ) meets. Contraption ( 4 ) according to one of claims 2 to 6, characterized in that the interface ( 3.1 ) or the interface ( 5.1 ) is formed of a dielectric layer, a metallic layer or a light-absorbing layer. Contraption ( 4 ) according to one of the preceding claims, characterized in that the light sources ( 2.1 to 2.n ) are in several columns and rows of an LED array (A) arranged light-emitting diodes. Luminaire comprising a device ( 4 ) according to any one of the preceding claims. Luminaire according to claim 9, characterized in that the lamp is a vehicle headlight.

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