DE102022120577A1 - Device and method for illuminating a vehicle apron - Google Patents

Abstract

The invention relates to a device for illuminating a vehicle apron (1) with a lighting unit (3) integrated in a vehicle (2) for generating a predetermined light distribution in the vehicle apron (1), a detection unit (6) for detecting objects (O1, O2 ) and/or ambient lighting (8) in the vehicle apron (1), a control unit (7) for controlling the lighting unit (3), a computing unit (10) for processing and/or evaluating data, the detection unit (6) as detection data has: means for detecting a brightness of the object (O1, O2), means for detecting the ambient lighting (8) of the vehicle apron (1), which is generated by a light source (9) arranged outside the vehicle (2), that the computing unit ( 10) has means for calculating a current contrast (K1, K2) of the object (O1, O2) from the detection data and means for calculating a changed contrast (K1', K2') of the object (O1, O2) depending on the changed Control of the lighting unit (3) in the lighting states of the object (O1, O2) and depending on the ambient lighting (8) of the object (O1, O2), means for generating a control signal (14) for the lighting unit (3) depending on a Comparison of the current contrast (K1, K2) of the object (O1, O2) and the calculated contrasts (K1', K2') of the objects (O1, O2).

Description

The invention relates to a device for illuminating a vehicle apron with a lighting unit integrated in a vehicle for generating a predetermined light distribution in the vehicle apron, a detection unit for detecting objects and / or ambient lighting in the vehicle apron, a control unit for controlling the lighting unit, a computing unit for processing and/or evaluation of data.

The invention further relates to a method for controlling a lighting unit of a vehicle, wherein the lighting unit illuminates a vehicle apron, which is additionally illuminated by ambient lighting from a different direction, an object located in the vehicle apron being detected and a location or position thereof determined the vehicle apron.

From the DE 10 2005 041 234 A1 a device for illuminating a vehicle apron is known, which has a lighting unit with a plurality of lighting elements (LED light sources) arranged in a matrix-like manner and each individually controllable, so that the lighting unit is controlled in this way depending on detection data provided by a detection unit about an object in the vehicle apron is that the object is illuminated with a reduced luminance, so that the object, for example designed as another road user, is not blinded.

For object recognition, for example, it is from the DE 10 2018 123 779 A1 known to use LIDAR sensors.

From the EP 3 090 913 B1 It is known to use a camera as a detection unit for object recognition. Possible objects are recognized from the image data of the vehicle apron using a computing unit.

From the EP 3 070 641 B1 a device for illuminating a vehicle apron is known, which has a detection unit designed as a stereo camera for detecting objects. The object detection takes place by generating differently patterned light distributions, which is caused by a lighting unit.

However, object detection is difficult if the environmental conditions are not ideal and the reflectance of the object itself is unfavorable compared to the surroundings. In particular, if the ambient lighting is stationary street lighting, a relatively high background luminance is achieved behind the object. If the reflectance of the object is comparatively low, it may happen that the contrast between the object and the surroundings is so low that the object cannot be localized or recognized. It is desirable to produce sufficient contrast between the object and its surroundings by changing the illumination of the object using a lighting unit of the vehicle.

The object of the present invention is therefore to develop a device and a method for illuminating a vehicle apron in such a way that illumination of objects adapted to the environmental conditions is achieved, with optical recognition of the objects being guaranteed.

To solve this problem, the invention in conjunction with the preamble of claim 1 is characterized in that the detection unit has as detection data: means for detecting a brightness of the object, means for detecting the ambient lighting of the vehicle apron, which is generated by a light source arranged outside the vehicle is that the computing unit has means for calculating a current contrast of the object from the detection data and means for calculating a changed contrast of the object depending on lighting states of the object that can be achieved by changing the control of the lighting unit and depending on the ambient lighting of the object, means for generating a control signal for the lighting unit depending on a comparison of the current contrast of the object and the calculated contrasts of the objects.

The particular advantage of the invention is that by determining the current contrast of an object in comparison to its surroundings, optimal illumination of the object in the area in front of the vehicle can be achieved. Here, a lighting unit illuminating the vehicle in front is controlled in a modified manner so that a high background luminance behind the object caused by ambient lighting, in particular street lighting, can be compensated for. For example, if the background luminance of the object is relatively high due to street lighting, a negative contrast can be generated by the lighting unit by reducing the illuminance of the object from the front, so that a relatively dark object can be recognized against a light background. This can be done, for example, by targeted dimming of lighting elements that at least illuminate the object.

According to a further development of the invention, a control signal for controlling the lighting unit is selected from a control database of the device, in which classified parameters relating to the reflectance of the object and the current ambient lighting are stored, so that an optimal light distribution can be generated using the corresponding control signal .

According to a further development of the invention, the control signal only affects the lighting elements that are provided to illuminate the object. The lighting in the other areas of the vehicle apron where there is no object remains unchanged.

According to a preferred embodiment of the invention, the lighting unit is designed as a high-resolution headlight that has a plurality of individually controllable light sources or an LCD display or a micromirror array. In this way, the light distribution can be specifically adjusted depending on the determined contrast of the object.

According to a further development of the invention, the device has a computing unit so that a first contrast of the object is calculated when the lighting unit is switched on and a second contrast of the same object is calculated when the lighting unit is switched off. The determined contrast values are compared to determine whether the first contrast or the second contrast has a higher contrast value. Depending on the comparison, the control signal for the lighting unit is selected, so that the lighting element provided for illuminating the object is switched on or off. With this control of the lighting unit, a database can advantageously be dispensed with.

According to a further development of the invention, the computing unit has means by means of which contrast values of several objects are determined when the lighting unit is switched on or off. From the two possible combinations of a first object and a second object with the lighting unit switched on, on the one hand, and a second contrast of the first object and the second object with the lighting unit switched off, on the other hand, this combination is selected which offers the maximum contrast value as a comparison value. This ensures that the illumination of several objects is optimized in a simple manner when a headlight without high resolution is provided.

According to a further development of the invention, the determination of the control signal for the lighting unit depends on a determined degree of reflection of the object. The reflectance of the object is preferably determined by comparing determined brightness data of the object to a reference table.

According to a further development of the invention, the control signal for the lighting unit is activated depending on a street lighting database in which different intensities of street lighting and / or different types of street lighting are summarized in lighting classes. The control signal can be defined by comparing the current street lighting resulting from the detection of the ambient lighting with the lighting classes stored in the street lighting database. This can advantageously reduce the number of different activations of the lighting unit.

According to a further development of the invention, the detection unit has a camera and/or a radar sensor and/or a LIDAR sensor. The camera provides image data of the vehicle apron from which the brightness data can be extracted depending on the location.

To solve the problem, the invention in conjunction with the preamble of patent claim 11 is characterized in that a brightness of the object and a brightness of an environment of the object are determined, that a contrast of the object is determined by comparing brightness data of the object and the environment or by comparison the determined brightness data of the object and the environment is determined to become reference data, that at least one further contrast of the object is calculated when the control of the lighting unit is changed, that the control signal for controlling the lighting unit is changed if the calculated changed contrast is greater than the current contrast of the object.

The particular advantage of the method according to the invention is that an optimization of the illumination of the object can be achieved by comparing the current contrast of an object in the area in front of the vehicle with stored data and/or data that can be calculated by varying the control of the lighting unit. Here, the current contrast of the object is preferably compared with a possible minimum contrast value and/or a maximum contrast value that is possible due to the lighting unit and the correspondingly determined environmental conditions. The resulting improvement in contrast of the object leads to better recognition of the object in the area surrounding the vehicle apron.

Further advantages of the invention result from the further subclaims.

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

• 1 Eine schematische Darstellung einer Beleuchtungsvorrichtung,
• 2 Ein Ablaufdiagramm von einem Ansteuerungsverfahren eines Scheinwerfers, um ein Objekt in einem Fahrzeugvorfeld optimal auszuleuchten und
• 3 Diagramm einer einzustellenden Leuchtweite oder für die Beleuchtung des Objektes verantwortliche Leuchtelemente eines Scheinwerfers in Abhängigkeit von Straßenbeleuchtungsklassen und eines Reflexionsgrades eines Objektes.

Show it:

• 1 A schematic representation of a lighting device,
• 2 A flowchart of a headlight control method in order to optimally illuminate an object in the area in front of a vehicle
• 3 Diagram of a headlight range to be adjusted or the lighting elements of a headlight responsible for illuminating the object depending on street lighting classes and the degree of reflectance of an object.

A device according to the invention for illuminating a vehicle apron 1 is arranged integrated in a vehicle 2. The device comprises a lighting unit 3 for generating light 4, by means of which a predetermined light distribution can be generated, for example a low beam distribution, country road light distribution, city light distribution, etc. The lighting unit 3 is designed as a headlight, preferably as a high-resolution headlight.

The high-resolution headlight has, for example, a plurality of lighting elements arranged in a matrix-like manner and individually controllable, the lighting elements being designed as LED light sources. Alternatively, the high-resolution headlight can also have a liquid crystal field with a plurality of liquid crystal elements, which can be controlled individually and each transmit or block light emitted by a light source. Alternatively, instead of such a liquid crystal arrangement (LCD arrangement), a surface modulation device with a DMD element (Digital Micromirror Device) can also be provided, with individually controllable micromirrors transmitting light or not. The high-resolution headlight allows areas of the light distribution to be hidden or dimmed down so that objects, such as pedestrians, are avoided.

Furthermore, the device according to the invention comprises a detection unit 6 for detecting objects in the vehicle apron 1. The vehicle apron 1 detected by the detection unit 6 is not limited to a distance of the objects from the vehicle of, for example, 40 meters. The objects can also be arranged further away from the vehicle 2, so that the vehicle apron 1 extends further than 40 meters from the vehicle 2. The size and in particular the length of the vehicle apron 1, which extends in the longitudinal axis of the vehicle 2, depends on the detection range Detection unit 6. The detection unit 6 can, for example, have a camera 6 ', which records an image of the vehicle apron 1 and makes it available to an electronic control unit 7. Furthermore, the detection unit 6 can have a LIDAR sensor (not shown) and/or a radar sensor in order to determine distances from detected objects.

The camera 6' can in particular determine the brightness of detected objects. The camera 6' can, in addition to other sensors, also be used to detect or determine ambient lighting or ambient luminance, so that an influence of street lighting 8 by street lights 9 can be estimated or determined. Since the street light 9 is arranged several meters above the street, the street lighting 8 is essentially perpendicular to the street. Objects, such as people, cannot be illuminated well as a result. Instead, there is a relatively light background. If the objects are additionally illuminated from the front by the lighting unit 4, the objects appear bright against a light background. This reduces the contrast so that the objects are less easily recognizable. The invention provides a method or a device for optimizing the contrast of objects on the road or in the area in front of the vehicle. The lighting unit 3 is modified depending on the ambient lighting 8 and a reflectance of the objects so that sufficient contrast of the objects is ensured for recognizing them.

In the present exemplary embodiment according to 1 Let it be assumed that a first object O1 and a second object O2 are located in the vehicle apron 1 at approximately the same distance from the vehicle 2. The objects O1, 02 are people, with the first object O1 having clothing with a reflectance of 50% and the second object O2 having clothing with a reflectance of 15%. In addition, the objects O1, 02 are illuminated essentially from above by the street lighting 8. If the lighting unit 3 is in a switched-on state, for example to generate a city light distribution, the second object O2 with the lower reflectance would have such a low contrast to the surroundings that it cannot be visually recognized. Only the first object O1 would be visually recognizable due to the high degree of reflectance. According to the invention, it is provided to control the lighting elements of the lighting unit 3 in such a way that Objects O1, 02 have either a positive contrast (objects appear bright against a dark background) or a negative contrast (objects appear dark against a light background).

To fulfill this purpose, the control unit 7 has a computing unit 10, which contains an algorithm for optimizing the contrast of the objects O1, O2. How out 2 As can be seen, in a first step S1, object recognition of the first object O1 and the second object O2 takes place by sensors of the detection unit 6. The camera 6 'of the detection unit 6 measures, on the one hand, the brightness of the first object O1 and the second object O2 as well as a Ambient luminance to the objects O1, O2, so that the type of street lighting 8 can be estimated based on this detection data.

In a second step S2, the reflectance of the recognized objects O1, O2 is determined. For this purpose, the camera 6' determines the brightness of the first object O1 and the second object O2. By comparing with reference values (reference data) stored in a reference database 11, the degree of reflection of the first object O1 and the second object O2 can be determined. The degree of reflection of the objects O1, O2 of course takes into account the illumination of the same by the lighting unit 3.

In a third step S3, the realizable or changed contrasts of the objects O1, O2 are calculated so that they can be recognized against the background in an illumination state that has changed from the current illumination state. For this purpose, an algorithm is provided which runs in the computing unit 10. According to a first variant of the control of the lighting unit 3, the lighting unit 3 is controlled depending on diagram 13 stored in a control database 12, which is in 3 is shown. It is assumed that in step S1 the current street lighting 8 could be estimated, so that one of the street lighting classes M3, M4, M5, M6 according to the DIN EN 13201-2 is present. These street lighting classes M3, M4, M5, M6 represent differently categorized street lighting parameters. From M6 to M3, the street lighting intensity increases. Furthermore, it is assumed that the reflectance S2 of the objects O1, O2 has been determined. Using diagram 13, the result for the first object O1 with a reflectance of 50% and a street lighting class M4 is that the lighting unit 3 or the lighting elements provided for illuminating the first object O1 should be switched on and thus the first object O1 should be illuminated . For the second object O2 with a reflectance of 15%, it follows from diagram 13 that it should not be illuminated by the lighting unit 3, so that a negative contrast would be created that would be sufficient to detect the second object O2. With regard to the first object O1, a positive contrast would occur because the first object O1 appears significantly brighter than the background. This exemplary embodiment relates to objects O1, O2, which are arranged at essentially the same distance from the vehicle 2. The diagram 13 is therefore only a section of an overall diagram, not shown, which provides values depending on a distance of the object O1, O2 from the vehicle 2. If the objects O1 and O2 are at different distances or at a different distance from the vehicle, the overall diagram has different control values depending on the distance compared to the diagram 13. In a next step S4, the lighting unit 3 is controlled, the individually controllable lighting elements of the lighting unit 3 being controlled in such a way that the first object O1 is illuminated and the second object O2 is not is illuminated. After completing step S4, step S1 and the following steps S2, S3 and S4 are repeated. The steps S1, S2, S3, S4 are thus repeated repeatedly, so that an optimization of the contrast of the objects O1, O2 is guaranteed depending on the changed environmental conditions and/or the object O1, O2 itself.

According to an alternative variant, the contrast of the first object O1 and the second object O2 can be calculated in the computing unit 10, the contrast being determined from the difference between the luminance of the object O1 or O2 and the ambient lighting based on the luminance surrounding detection. Alternatively, another measure for the detectability of the objects O1, O2 can also be calculated, for example the ratio of the contrast to a contrast threshold. The contrast threshold is an experimentally determined value and depends, among other things, on the object size and the ambient luminance.

$$\text{max}\left(\text{K}\mathrm{2,}\text{K}2\text{'},\text{K}2\text{"}\dots \right)=\text{K}{2}_{\text{max}}\text{;}$$

The computing unit 10 carries out several computing operations. On the one hand, a contrast K1 of the first object O1 and a contrast K2 of the second object O2 are calculated in the current switched-on state of the lighting unit 3. In addition, a calculation process takes place in which a contrast K1 'of the first object O1 and K2' of the second object O2 is calculated with the lighting unit 3 switched off. If necessary, further contrasts K1 "of the first object O1 and further contrasts K2" of the second object O2 can be calculated are in a dimmed switch-on state by lights provided for illuminating the first object O1 and the second object O2 elements of the lighting unit 3. In a further calculation step, the maximum contrast value K1 _max , K2 _max of the determined contrast values K1, K1', K1'' or K2, K2', K2" is then selected accordingly $$\text{Max}\left(\text{K}\mathrm{1,}\text{K}1\text{'};\text{K}1\text{"}\dots \right)=\text{K}{1}_{\text{Max}}\text{;}$$

$$\text{Max}\left(\text{K}\mathrm{2,}\text{K}2\text{'},\text{K}2\text{"}\dots \right)=\text{K}{2}_{\text{Max}}\text{;}$$

The maximum value K1 _max , K2 _max of these contrast values for the different objects O1, O2 corresponds to a degree of illumination of the corresponding object O1, O2 corresponding to a switched-on state or an switched-off state of the lighting element or in the dimmed state of the same. The maximum contrast value K1 _max or K2 _max thus corresponds to control values for the lighting unit 3. In the present exemplary embodiment, K1max would mean that the first object O1 would be illuminated by corresponding lighting elements of the lighting unit 3. In the present exemplary embodiment, K2max would mean that the second object O2 would not be illuminated, i.e. corresponding lighting elements of the lighting unit 3 would have to be switched off. A control signal 14, which is sent by the control unit 7 to the lighting unit 3, is thus modified in such a way that the lighting elements provided for illuminating the first object O1 are switched on and the lighting elements provided for illuminating the second object O2 are switched off. The other lighting elements of the lighting unit 3, which are used to illuminate the surroundings of the objects O1, O2, are not controlled in any changed way or continue to shine with the same illuminance.

According to an alternative embodiment of the invention, in which the lighting unit 3 is not a high-resolution headlight, but rather has such a low resolution that the objects 01, 02 cannot be blocked out, a modified calculation rule is carried out in the computing unit 10 In accordance with the first variant of the invention, the contrast K1 and K1' or K2 and K2' of the objects O1, O2 is calculated in the switched-on state and in the switched-off state of the lighting unit 3. The control signal 14 can only have two states, namely the “on” state when the lighting unit 3 is switched on and the “off” state when the lighting unit 3 is switched off. From the possible combinations K1, K2 when the lighting unit 3 is switched on on the one hand and K1 ', K2' on the one hand When the lighting unit 3 is switched off, on the other hand, the maximum K _max is formed according to the regulation $${\text{K}}_{\text{Max}}=\text{Max}\left(\left(\text{<figure-callout id="1" label="K" filenames="DE102022120577A1\_0005.png" state="{{state}}">K</figure-callout>}1;\text{K}2\right)\text{;}\left(\text{K}1\text{'},\text{K}2\text{'}\right)\right)$$

For example, if the contrast K1 is high and the contrast K2 is small on the one hand, and if the contrast K1 is high (the same level as contrast K1) and the contrast K2' is greater than the contrast K2, the control signal 14 would be determined in accordance with the contrasts K1' and K2' become. This ensures that both objects O1, O2 are illuminated with a sufficiently high contrast, with the less visible object O1, O2 also being clearly visible.

Reference symbol list

1

vehicle apron

2

vehicle

3

Light unit

4

Light

6.6'

Detection unit/camera

7

Control unit

8th

Street lighting

9

Street light

10

Computing unit

11

Reference database

12

Control database

13

diagram

14

Control signal

01.02

Objects

S1-S4

Steps 1 to 4

M3-M6

Street lighting classes

K1,K2

first contrast

K1',K2'

second contrast

K1max, K2max

maximum contrast value

Kmax

maximum

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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 102005041234 A1 [0003]
• DE 102018123779 A1 [0004]
• EP 3090913 B1 [0005]
• EP 3070641 B1 [0006]

Non-patent literature cited

• DIN EN 13201-2 [0031]

Claims (14)

Device for illuminating a vehicle apron (1) with - a lighting unit (3) integrated in a vehicle (2) for generating a predetermined light distribution in the vehicle apron (1), - a detection unit (6) for detecting objects (O1, O2) and /or ambient lighting (8) in the vehicle apron (1), - a control unit (7) for controlling the lighting unit (3), - a computing unit (10) for processing and / or evaluating data, characterized in that the detection unit (6 ) as detection data: - means for detecting a brightness of the object (O1, O2), - means for detecting the ambient lighting (8) of the vehicle apron (1), which is generated by a light source (9) arranged outside the vehicle (2). that the computing unit (10) has means for calculating a current contrast (K1, K2) of the object (O1, O2) from the detection data and means for calculating a changed contrast (K1', K2') of the object (O1, O2 ) depending on the lighting states of the object (O1, O2) that can be achieved by changing the control of the lighting unit (3) and depending on the ambient lighting (8) of the object (O1, O2), - means for generating a control signal (14) for the lighting unit (3) depending on a comparison of the current contrast (K1, K2) of the object (O1, O2) and the calculated contrasts (K1', K2') of the objects (O1, O2). Device according to Claim 1 , characterized in that the computing unit (10) has means for calculating a maximum contrast (K1 _max , K2 _max ) from the current contrast (K1, K2) of the object (O1, O2) and that calculated by variable control of the lighting unit (3). Contrasts (K1 ', K2') of the object (O1, O2). Device according to Claim 1 or 2 , characterized in that the computing unit (10) has means for selecting the control signal (14) from a control database (12), control signals (14) stored in the control database (12) for differently categorized street lighting parameters (M3, M4, M5, M6). ) are saved. Device according to one of the Claims 1 until 3 , characterized in that the control signal (14) for the lighting unit (3) is designed such that only lighting elements of the lighting unit (3) are controlled which illuminate the area of the vehicle apron (1) in which the object (O1, O2 ) is located. Device according to one of the Claims 1 until 4 , characterized in that the lighting unit (3) is designed as a high-resolution headlight with a plurality of individually controllable lighting elements. Device according to one of the Claims 1 until 5 , characterized in that the computing unit (10) has, on the one hand, means for calculating a first contrast (K1, K2) of the object (O1, O2) when the lighting unit (3) is switched on and means for calculating a second contrast (K1 ', K2') of the Object (O1, O2) with the lighting unit (3) switched off and/or means for calculating a further contrast (K1', K2') of the object (O1, O2) in the dimmed on state of the lighting unit (3), means for comparing the first Contrast (K1, K2) and the second contrast (K1', K2') and possibly further contrasts (K1", K2") in such a way that the lighting unit (3) with the to a maximum contrast value (K1 _max , K2 _max ) , which is calculated from the first contrast (K1, K2) and the second contrast (K1', K2') and possibly the further contrast (K1", K2"), the corresponding control signal (14) controls the lighting unit (3). Device according to one of the Claims 1 until 6 , characterized in that the control signal (14) for controlling the lighting unit (3) is dependent on a distance of the object (O1, O2) from the device and / or on a reflectance of the object (O1, O2). Device according to one of the Claims 1 until 7 , characterized in that the degree of reflection of the object (O1, O2) is determined by comparing brightness data of the object (O1, O2) determined by the detection unit (6) with reference data stored in a reference database (11). Device according to one of the Claims 1 until 8th , characterized in that the ambient lighting (8) is formed by street lighting (9), the street lighting (9) being classified in a control database (12) using multiple street lighting parameters S (M3, M4, M5, M6), each with different illuminance ranges is. Device according to one of the Claims 1 until 9 , characterized in that the detection unit (6) has a camera (6 ') and / or a radar sensor and / or a LIDAR sensor. Method for controlling a lighting unit (3) of a vehicle (2), wherein the lighting unit (3) illuminates a vehicle apron (1), which is additionally illuminated by ambient lighting (8) from a different direction, such that a vehicle apron (1) Object (O1, O2) located is detected by determining its location in the vehicle apron (1), characterized in that - a brightness of the object (O1, O2) and a brightness of an environment of the object (O1, O2) are determined, - that a contrast (K1, K2) of the object (O1, O2) is determined by comparing brightness data of the object (O1, O2) and the environment or by comparing the determined brightness data of the object (O1, O2) and the environment to reference data - that at least one further contrast (K1', K2') of the object (O1, O2) is calculated when the control of the lighting unit (3) is changed, - that the control signal (14) for controlling the lighting unit (3) is changed if the calculated changed contrast (K1', K2') is greater than the current contrast (K1, K2) of the object (O1, O2). Procedure according to Claim 11 , characterized in that the contrast of the object (O1, O2) is determined when the lighting unit (3) is switched on and when the lighting unit (3) is switched off and / or when the lighting unit (3) is dimmed, that the determined values of the contrast (K1, K2; K1', K2';K1",K2") are compared with each other and that the highest value of the contrast (K1, K2; K1', K2';K1",K2") is used as the maximum contrast value (K1max, K2max) to form the Control signal (14) for the lighting unit (3) is used. Procedure according to Claim 11 or 12 , characterized in that only the lighting elements of the lighting unit (3) are controlled depending on the calculated maximum contrast value (K1 _max , K2 _max ) of the object (O1, O2), through which the object (O1, O2) is illuminated. Procedure according to one of the Claims 11 until 13 , characterized in that a degree of reflection of the object (O1, O2) is determined by comparing the current brightness value of the object (O1, O2) with reflection data stored in a stored reflection database (11) and that depending on the degree of reflection of the object (O1, O2), the control signal (14) is generated depending on the ambient lighting (8) and depending on the distance of the object (O1, O2).

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