DE102016200590A1 - Lighting device and method for monitoring a lighting device - Google Patents

Abstract

The present invention relates to the monitoring of a lighting device with a scanning, directed light beam. In this case, after deflecting the scanning light beam, part of the light intensity is decoupled and detected by means of a two-dimensional image sensor. The image data thus detected by the image sensor is compared with a target value, and if there is a deviation, an error in the lighting device can be deduced.

Description

The present invention relates to a lighting device and a method for monitoring a lighting device. In particular, the present invention relates to monitoring a lighting device comprising a deflection device, wherein the deflection device deflects a directed light beam emitted by a light source.

State of the art

The German patent application DE 10 2011 080 559 A1 discloses a lighting device for a vehicle. The lighting device comprises a light source and a light guide unit for generating a predetermined light distribution. The light guide unit in this case comprises a deflection surface with a plurality of micromirrors which can be adjusted independently of one another about a pivot axis.

Laser-based light modules are used, for example, in automobile headlights. In addition, laser-based, scanning illumination modules are increasingly being used in numerous fields of application. In this case, a directed light beam, for example, from a laser source, deflected by a scanning mirror system with one-dimensional or two-dimensional deflection on a converter. This converter converts the usually monochromatic light into a broad wavelength spectrum, whereby the exiting light, for example, appears in the sum as white light. By suitable control of the deflection system and synchronous switching of the laser source, different adapted light distributions can be generated.

For this principle, laser powers in the range of several watts are required. In combination with a relatively small beam diameter, optionally less than one millimeter, this results in a high power density in the scanning light beam. Due to the high risk potential of such high-energy light beams, therefore, suitable security concepts are essential and in part prescribed by the legislator.

Disclosure of the invention

According to a first aspect, the present invention provides a lighting device having the features of independent claim 1.

The present invention provides a lighting device with a light source, a deflection device, a beam splitter, an image sensor and an evaluation device. The light source is designed to emit a directed light beam. The deflection device is designed to deflect the directed light beam of the light source. The beam splitter is designed to decouple a portion of the deflected by the deflecting light beam. The image sensor is designed to detect the portion of the light beam coupled out by the beam splitter and to provide an output signal corresponding to the detected light beam. The evaluation device is designed to receive the output signal provided by the image sensor, and to detect a malfunction of the illumination device if the output signal provided by the image sensor deviates from a predetermined desired value.

According to a further aspect, the present invention provides a method for monitoring a lighting device having the features of independent patent claim 10.

In accordance with this aspect, the present invention provides a method of monitoring a lighting device having a deflector that deflects a directional light beam emitted from a light source. The method in this case comprises the steps of decoupling a part of the light beam deflected by the deflection device and detecting the decoupled part of the deflected light beam with an image sensor. Further, the method includes a step of detecting a malfunction of the lighting device when the detected decoupled portion of the deflected light beam deviates from a predetermined desired value.

Advantages of the invention

The present invention is based on the idea to decouple a part of the scanning light beam in a scanning illumination system by means of a beam splitter and to detect and evaluate this decoupled part of the scanning light beam by means of an image sensor. In particular, the image sensor may be a planar, that is to say a two-dimensional image sensor. In this way, a complete detection of the scanning light beam is possible. In particular, errors that are caused by a faulty deflection of the directed light beam can therefore be detected directly. In this way it is possible to detect errors in the control of the deflecting device for the directional light beam. In addition, a faulty deflection of the directional light beam due to damage or incorrect adjustment of the deflector can be detected very easily. Finally, can also be faulty Distractions due to thermal deformation or the like during operation of the lighting device can be detected quickly and reliably.

Since the beam splitter of the illumination device according to the invention decouples a part of the light beam after the light beam has been deflected by the deflection device, the image signal detected by the image sensor and subsequently evaluated corresponds to the light pattern output by the illumination device. Thus, it is possible to deduce the illumination pattern directly from the light pattern detected by the image sensor without any further elaborate processing steps. In this way, a particularly simple and efficient monitoring of the output by the illumination device illumination pattern is possible.

The light source may be, for example, a laser source. In particular, for example, laser sources based on semiconductor diodes are possible which emit laser light at a predetermined wavelength. For example, as a light source, a laser source with blue light in the range between 400 and 500 nm, in particular 450 nm possible. In addition, however, any other light sources, in particular also laser sources with any other wavelength are possible. For example, laser sources in the infrared range or in the ultraviolet wavelength range are also possible. Furthermore, it is also possible to combine laser beams of different wavelengths. As a result, for example, a light beam can be provided whose light comprises a plurality of color components. For example, red (R), green (G) and blue (B) light can be combined to form an RGB light beam.

According to an embodiment, the lighting device further comprises a conversion device. This conversion device is designed to at least partially convert a wavelength of the light beam emitted by the light source into at least one further wavelength. By means of such a conversion device in the lighting device, it is possible to convert the monochromatic light of the light source into light of several wavelengths, in particular into light of a light spectrum. In this way, for example, monochromatic blue light can be converted into light of a broader wavelength spectrum by means of the conversion device, so that, for example, white light appears as the sum.

According to one embodiment, the conversion device is arranged in the beam path between the deflection device and the beam splitter. In this way, the deflected and converted light is coupled out by the beam splitter and fed to the image sensor. In this case, the image sensor can thus detect the light already converted by the conversion device. In this way, a check of the correct light conversion by the conversion device is also possible by the image sensor and the downstream evaluation.

According to an alternative embodiment, the beam splitter is arranged between the deflection device and the conversion device. In this way, the beam splitter can decouple the scanning light beam before the light has been converted by the converting device. Thus, by the image sensor and the downstream evaluation device, the detection of the deflected light beam, which includes only the wavelength or wavelengths of the light emitted from the light source. Thus, the image sensor can be easily adjusted to the wavelength or wavelengths of this light to be detected.

According to a further embodiment, the evaluation device is designed to evaluate a local light distribution on the image sensor and / or a light color of the light detected by the light sensor. By evaluating the local light distribution on the image sensor, an error in the control of the deflection device or in the control of the laser source can be detected. In addition, an optionally faulty synchronization can be detected by the evaluation of the local light distribution. By evaluating the light color of the light detected by the light sensor, that is to say by detecting the wavelengths detected by the image sensor or the color spectrum, it is possible, for example, to detect a defect in the conversion device.

According to a further embodiment, the evaluation device is designed to switch off the light source when a malfunction has been detected. In this way, a safety shutdown can be carried out in the event of a detected fault in the lighting device in order to avoid a potential risk potential.

According to a further embodiment, the image sensor is designed as a two-dimensional image sensor. In particular, the image sensor may be, for example, a digital image sensor, such as a CCD or CMOS sensor. Depending on the application, the image sensor can be embodied as an image sensor which exclusively detects a light intensity for one or more predetermined wavelengths or a predetermined wavelength spectrum. Alternatively, the image sensor can also be designed as a color sensor, the In addition to the pure intensity and the light color, that is, the wavelength or the wavelength spectrum of the incident light detected.

According to a further embodiment, the lighting device comprises a control device. The control device is designed to control the deflection device. Furthermore, the control device is designed to adapt the control of the deflection device using the output signal provided by the image sensor. In this way, it is possible to adjust the control of the deflection device, or possibly also other components of the lighting device in real time and thus to compensate for possible faults or errors already during operation. Thus, for example, fluctuations in the deflection due to temperature changes or the like can be compensated for in real time.

According to one embodiment, the beam splitter is designed to decouple less than 1% of the light intensity of the light incident on the beam splitter. In particular, the beam splitter can also decouple less than 0.5% or 0.1% of the light intensity of the light incident on the beam splitter. Moreover, it is also possible to decouple an even smaller proportion of the light intensity through the beam splitter, for example 0.01% or possibly even only 0.001%. In one embodiment, the beam splitter couples a constant proportion of the light intensity over the entire scan area of the illumination device, that is, over the entire area over which the deflection device deflects the directed light beam. Alternatively, it is also conceivable for the deflecting device to decouple part of the light intensity of the directed light beam only in a predetermined subarea of the scanning region, for example in an edge region or in a central region in the middle of the scanning region.

According to one embodiment, the coupling device comprises a micromirror device with a microelectromechanical system. In particular, the deflection device may comprise a micromirror device in which a micro-mirror can be deflected in two spatial directions by means of a microelectromechanical system. Alternatively, deflection devices with two micromirror devices connected in series are also possible, in which the micromirror can only be deflected in one spatial direction. In addition, any other deflection devices are possible as a deflection, which are able to control the light distribution from a light source. In particular, for example, digital micro mirror devices (digital micro mirror device DMD) are possible, which allow a variable light distribution with a modulated area density.

According to a further aspect, the present invention provides a headlight, in particular a headlight for a motor vehicle with a lighting device according to the invention. In addition, other lighting devices for lighting systems in the visible and invisible wavelength range are possible.

Further embodiments and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

Brief description of the drawings

Showing:

1 : a schematic representation of a lighting device according to an embodiment;

2 a schematic representation of a lighting device according to another embodiment; and

3 3 is a schematic representation of a flow chart underlying a method according to one embodiment of the present invention.

1 shows a schematic representation of a lighting device 1 according to one embodiment. The lighting device comprises a light source 10 a deflector 20 , a beam splitter 40 , an image sensor 50 as well as an evaluation device 60 , In addition, the lighting device may be a conversion device 30 include. Furthermore, a plurality of optical lenses or lens systems are possible, which are largely not shown for better understanding of the present invention. Only an imaging lens 70 is shown for illustrative purposes. In the embodiments described below, the same or similar components are provided with the same reference numerals. In addition, the embodiments described below, as far as they do not fundamentally contradict each other, also arbitrarily combine. It goes without saying that further additions as well as modifications of the described embodiments are also included in the subject matter of the present invention.

At the light source 10 it may in principle be any light source designed to receive a directed beam of light emit. In particular, for example, laser sources are possible which emit a directed light beam. Such laser sources can be realized for example by means of suitable semiconductor diodes. In particular, directed light sources are possible in which a plurality of individual light beams are combined to form a common directional light beam. The light source 10 can emit, for example, monochromatic light of a given wavelength. For example, this may be monochromatic light in the visible range, such as, for example, in the blue wavelength range between 400 and 500 nm, in particular around 450 nm. But also monochromatic light of a different wavelength, especially in the ultraviolet or infrared wavelength range is also possible. In addition, the light source can 10 also emit a directed light beam with light that includes multiple wavelengths, or even a wavelength spectrum. In particular, it is possible that the light source 10 comprises a plurality of individual light source elements, the light beams to a light beam in the light source 10 be combined into a common beam of light. In this case, the individual light source elements can emit either all light of the same wavelength, or alternatively also light with different wavelengths. Is in the light source 10 Combining light with several different wavelengths, it is thereby possible to provide a directed light beam with several different color components.

The one from the light source 10 Directed light beam emitted is in the direction of the deflection 20 directed. The directional light beam of the light source 10 meets the deflector 20 and is from the deflector 20 distracted in one or two spatial directions. For example, it may be at the deflection 20 to act a micro-mirror device in which a micromirror is deflected in two, preferably orthogonal to each other, spatial directions. In addition, there are also baffles 20 possible, in which two micromirrors are deflected in each case in a spatial direction, so that by direct connection of these two micromirrors also the directional light beam can be deflected in two spatial directions. The micromirrors can be deflected in particular by so-called microelectromechanical structures (MEMS) in order to deflect the directed light beam into the desired spatial direction. For this purpose, the corresponding microelectromechanical structures can be controlled by a suitable drive circuit (not shown here). Thus, that of the light source 10 emitted directed light beam through the deflector 20 deflected targeted, so that the deflected light beam scans a predetermined pattern. In this way, by means of a directed light beam, a predetermined two-dimensional illumination pattern can be projected by targeted deflection. The way through the deflection 20 deflected scanning light beam can then optionally through an optical system 70 be focused before it hits the surface to be illuminated.

After the light beam through the deflector 20 is deflected, is then by means of a beam splitter 40 a part of the deflected light beam decoupled. The beam splitter 40 can decouple a part of the deflected light beam over the entire scanning range of the deflected light beam. In this case, the extension of the beam splitter 40 at least as large as the scanning range of the deflected light beam. Alternatively, it is also possible that the beam splitter 40 decoupling part of the deflected light only in a part of the scanning range of the deflected light beam. For example, the beam splitter 40 be arranged in an edge region of the scan area. Alternatively, it is also conceivable, the beam splitter 40 only in a central area within the scanning range of the deflected light beam, wherein the beam splitter 40 smaller, in particular substantially smaller than the scanning range of the deflected light beam.

At the beam splitter 40 it may, for example, be a so-called beam splitter plate. In this case, such a beam splitter plate reflects a part of the light incident on the beam splitter plate, while the remaining part of the light incident on the beam splitter plate transmits through the beam splitter plate. Preferably, the beam splitter couples 40 In this case, only a very small proportion of the light intensity of the deflected light beam, so that the majority of the deflected light beam through the beam splitter 40 transmitted. For example, through the beam splitter 40 less than 1%, in particular less than 0.1% of the light output of the deflected light beam are coupled out. But also beam splitter, which is 0.5% or 0.05% of the light output of the beam splitter 40 Disconnect incoming light are possible. In addition, are also beam splitters 40 possible that decouple a smaller proportion of the incident light output, for example, a maximum of 0.01% or 0.001%.

That through the beam splitter 40 decoupled light is thereby through the beam splitter 40 in the direction of the image sensor 50 distracted. At the image sensor 50 it can be a two-dimensional image sensor. For example, this image sensor may comprise a plurality of image sensing elements arranged on a two-dimensional surface. In particular, image sensors with CCD or CMOS sensors are possible. In addition, however, any other two-dimensional image sensors are possible. The image sensor 50 can either only a two-dimensional detection of the image sensor 50 perform incident light intensity. In this case, the image sensor 50 either selectively responsive only to light of one or more predetermined wavelengths. For example, this can be done in front of the image sensor 50 a suitable filter can be arranged. In addition, it is also possible that the image sensor 50 also captures and evaluates the intensity of the total incident light. Alternatively, however, it is also possible that the image sensor 50 In addition to the pure light intensity and the color, that is, the wavelength or the wavelength spectrum of the incident light detected. For example, image sensors with a plurality of sensor elements are possible for this, each having different sensitivities for different wavelengths. For example, the image sensor may be 40 also be a conventional image sensor, a conventional camera module or the like. Furthermore, it is also possible that the different colors by means of suitable color filters in front of individual sensor elements of the image sensor 40 can be selected.

Between the deflector 20 and the beam splitter 40 In addition, there may be a conversion device 30 be provided. This conversion device 30 For example, the wavelength of a part of the on the conversion device 30 incident light to another wavelength or wavelength spectrum. In this way, for example, light can be generated from the monochromatic light of the deflected directed light beam, which comprises a plurality of wavelengths or a wavelength spectrum. In this case, the beam splitter 40 decouple the light of the entire spectrum, that by the conversion device 30 was generated.

The image sensor 50 then sets to the detected light passing through the beam splitter 40 has been decoupled, corresponding output signal ready to the image sensor through the beam splitter 40 projected image. Optionally, it can be between beam splitter 40 and image sensor 50 still be an optical system of one or more optical lenses arranged. That of the image sensor 50 captured image is then from an evaluation device 60 recorded and analyzed. The evaluation device 60 can, for example, the image data of the image sensor 50 output signal compared with a predetermined pattern. This predetermined pattern can correspond, for example, to the image which, given a correct control of the deflection device 20 to be projected. This is the same as that of the image sensor 50 captured image and the desired target image wholly or at least approximately, so was the directional light beam through the deflector 20 distracted correctly and there is no error. However, this differs from the image sensor 50 captured image of the target image to be achieved significantly, so the evaluation 60 an error in the lighting device 1 detect. This error may be, for example, a faulty control of the deflection 20 act. For example, it is possible that due to heating no correct deflection of the directional light beam in the deflector 20 he follows. But also a damage of the lighting device 1 or further disturbances are also conceivable. Furthermore, it is possible that due to synchronization problems or the like, no correct deflection of the directional light beam has occurred. In this case, the evaluation device 60 for example, the lighting device 1 to avoid potential hazards due to a badly emitted light beam with high light intensity.

Alternatively, it is also possible that the evaluation device 60 or another control device that of the image sensor 50 recorded image data and then determines a deviation between the image to be achieved and the image actually captured. Based on this deviation, control parameters may then be calculated as necessary to control the deflection of the deflector 20 adapt. In this way, even during operation of the lighting device 1 an active control to compensate for possible disturbances or the like in real time possible.

In addition, upon a colored capture of the image sensor 50 projected image also a shift of the color spectrum or a local color change may be detected. The evaluation device 60 for example, that of the image sensor 50 detected color of the beam splitter 40 on the image sensor 50 capture the projected image and compare the color so captured with a desired setpoint for the color. Dodges through the image sensor 50 detected color of the predetermined color significantly, it may be, for example, a possible error or damage in the conversion device 30 getting closed. It is also possible in front of the image sensor 50 to arrange a corresponding color filter which is tuned to a predetermined wavelength or a predetermined wavelength spectrum. If the wavelength or the wavelength spectrum of the light incident on this color filter shifts, the proportion of the light transmitted or absorbed by the filter also changes, as a result of a change in the light transmitted through the image sensor 50 detected Light intensity leads. From this can then be concluded that a possible malfunction. If a change in the wavelength or the wavelength spectrum is detected, the light source can optionally be used 10 be adjusted accordingly to the color location, or the wavelength or the wavelength spectrum of the light source 10 to adapt to emitted light. In particular, the color locus can be adapted to compensate for the detected deviation.

The through the evaluation 60 determined parameters, such as the degree of correspondence between the actual projected by the deflected light beam image and a predetermined target image for the image to be projected and / or a color spectrum detected the image sensor can also be provided by the evaluation for further processing. In particular, the data thus acquired can be stored in an error memory or optionally also displayed on a display to a user.

2 shows a further embodiment of a lighting device 1 , The lighting device 1 In this embodiment, this largely corresponds to the previously described embodiment. Instead of a beam splitter 40 however, which reflects the small amount of light to be coupled out, is a beam splitter in this embodiment 40 provided in which the out-coupling, small proportion of the light through the beam splitter 40 while the remainder of the deflected light beam passes through the beam splitter 40 is reflected.

Moreover, it is also possible in this, as well as in the embodiment described above, beam splitter 40 and conversion device 50 to combine in a common component.

Furthermore, it is also possible, the conversion device 30 in the beam path after the beam splitter 40 arrange so that through the beam splitter 40 the light before conversion by the conversion device 30 is decoupled.

In addition, it is also possible that the conversion and the division of the light beam can be realized in a common component. For example, the conversion device 30 reflect the majority of the converted light while allowing a small amount of light described above by the conversion device 30 transmit. This transmitted light may then be received by the image sensor 50 recorded and evaluated. Likewise, a conversion device 30 possible in which the majority of the light is transmitted through the conversion device and thereby a small part of the light from the conversion device 30 is reflected. Here is the reflected light on the image sensor 50 be distracted and from the image sensor 50 recorded and evaluated.

3 shows a schematic representation of a flowchart, as a method for monitoring a lighting device 1 underlying and can be realized for example by the embodiments described above. In particular, by this method, a lighting device 1 with a deflector 20 be monitored at the deflection 20 from a light source 10 illuminated with a directed light beam. In a step S1, first part of the light beam deflected by the deflection device is coupled out. In step S2, the decoupled part of the deflected light beam is detected by an image sensor 50 detected, and in step S3, a malfunction of the lighting device 1 detected when the detected decoupled portion of the deflected light beam deviates from a predetermined desired value.

In summary, the present invention relates to the monitoring of a lighting device with a scanning, directed light beam. In this case, after deflecting the scanning light beam, part of the light intensity is decoupled and detected by means of a two-dimensional image sensor. The image data thus detected by the image sensor is compared with a target value, and if there is a deviation, an error in the lighting device can be deduced.

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 102011080559 A1 [0002]

Claims (10)

Lighting device ( 1 ), with: a light source ( 10 ) adapted to emit a directional beam of light; a deflection device ( 20 ) which is adapted to direct the directional light beam of the light source ( 10 ) to distract; a beam splitter ( 40 ), which is designed to cover a part of the deflection device ( 20 ) decoupled deflected light steel; an image sensor ( 50 ), which is adapted to that of the beam splitter ( 40 ) to detect the decoupled part of the light beam and to provide an output signal corresponding to the detected light beam; and an evaluation device ( 60 ), which is adapted to be used by the image sensor ( 50 ) and a malfunction of the lighting device ( 1 ), when the signal from the image sensor ( 50 ) provided output signal deviates from a predetermined desired value. Lighting device ( 1 ) according to claim 1, with a conversion device ( 30 ) configured to at least partially convert light having a wavelength of the light beam emitted from the light source into light having at least one further wavelength. Lighting device ( 1 ) according to claim 2, wherein said converting means ( 1 ) between the deflector ( 20 ) and the beam splitter ( 40 ) is arranged. Lighting device ( 1 ) according to one of claims 1 to 3, wherein the image sensor ( 50 ) comprises a two-dimensional sensor surface. Lighting device ( 1 ) according to one of claims 1 to 4, wherein the evaluation device ( 60 ) is adapted to local light distribution on the image sensor ( 50 ) and / or a light color of the image sensor ( 50 ) evaluated light. Lighting device ( 1 ) according to one of claims 1 to 5, wherein the evaluation device ( 60 ) is adapted to the light source ( 10 ) to turn off when a malfunction has been detected. Lighting device ( 1 ) according to one of claims 1 to 6, with a control device which is designed to control the deflection device ( 20 ), and the control of the deflection device ( 20 ) using the image sensor ( 50 ) adjusted output signal. Lighting device ( 1 ) according to one of claims 1 to 7, wherein the beam splitter ( 40 ) is less than 1 percent of the light intensity of the beam splitter ( 40 ) decoupling incident light beam. Lighting device ( 1 ) according to one of claims 1 to 8, wherein the deflection device ( 20 ) comprises a micromirror device having a microelectromechanical system. Method for monitoring a lighting device ( 1 ) with a deflection device ( 20 ), one from a light source ( 10 ) deflecting directed light beam, with the steps: decoupling (S1) of a part of the deflection device ( 20 ) deflected light beam; Detecting (S2) the decoupled part of the deflected light beam with an image sensor ( 50 ); and detecting (S3) a malfunction of the lighting device ( 1 ) when the detected decoupled portion of the deflected light beam deviates from a predetermined desired value.

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