Method for controlling a headlight of a motor vehicle

Abstract

Method for controlling a headlight of a motor vehicle, wherein the headlight comprises a plurality of light sources, and wherein the method comprises the following steps: - definition of a desired light distribution (1) of the headlight in a control device, wherein the desired light distribution (1) for the light sources each defines a desired intensity of the light emitted by the respective light source to be measured outside the headlight; - Conversion of the desired light distribution (1) into control values ​​for the light sources, taking into account an optical characteristic of the light sources, wherein the conversion comprises a multiplication of the light distribution by a conversion function (2), and wherein the optical characteristic influences the intensity of the respective light source to be measured from outside the headlight; - controlling the light sources with the control values; characterized in that the conversion function (2) has higher conversion factors for light sources arranged on the outside of the headlight than for light sources arranged on the inside of the headlight, wherein the terms "outside" and "inside" refer to a radial direction with respect to the optical axis of the headlight.

Description

[0001] The present invention relates to a method for controlling a headlight of a motor vehicle according to claim 1.

[0002] DE 10 2016 122 499 A1 discloses a method in which control values ​​for individual light sources of the headlight are defined in a control unit, with which these light sources are then controlled. The control values ​​are specified as percentages relative to the maximum power of the respective light source. The light sources may be identical. However, optical units of the headlight can have the effect that, with the same control value, the light from two light sources outside the headlight has different intensities. Therefore, an empirical or iterative approach is used to generate a specific light distribution with the headlight. This is an enormous effort when a headlight has a large number of light sources.

[0003] DE 10 2016 009 459 A1 discloses a method for adjusting the light distribution of a headlight with at least one control unit for adjusting the light distribution. The control unit has an interface designed to transmit parameters specified in a user specification to the control unit. The parameters are intended for adjusting and / or changing an illuminance distribution within the light distribution.

[0004] In contrast, the present invention is based on the object of simplifying the adjustment of a desired light distribution on a road in front of the motor vehicle.

[0005] This object is achieved by a method according to claim 1, a system according to claim 7, and a motor vehicle according to claim 8. Embodiments of the invention are specified in the dependent claims.

[0006] The headlight comprises several light sources, which can be implemented as LEDs, for example. The light sources can be arranged on a single module or distributed across several modules. In this description, a module is understood to mean, in particular, a component that comprises several light sources and an optical system. The optical system of a module is designed to redirect and / or focus the light emitted by the light sources of the same module.

[0007] First, a desired light distribution pattern for the headlight is defined in a control unit. The desired light distribution pattern can be stored, for example, in a memory of the control unit or generated by the control unit. The light distribution pattern defines the desired intensity of the light emitted by each light source, which can be measured outside the headlight.

[0008] The desired light distribution is converted into control values ​​for the light sources. In doing so, an optical characteristic of each light source is taken into account. The optical characteristic can be defined, for example, for each light source individually or for groups of light sources. The optical characteristic influences the intensity of the light source measured from outside the spotlight. For example, optical units of the spotlight can influence this intensity. The light sources are then controlled using the control values.

[0009] If the light sources are arranged on a single module, the desired light distribution can be converted directly into the control values ​​for the light sources. If the light sources are arranged on different modules of the headlight, the conversion can involve first dividing the desired light distribution into several desired module light distributions. Each module is assigned a desired module light distribution. The desired module light distributions are designed in such a way that, when used simultaneously in the headlight, they jointly produce the desired light distribution. The desired module light distributions can then be converted into the control values ​​for the light sources.

[0010] In contrast to the state of the art, this approach does not rely on control values ​​that must first be determined empirically and / or iteratively. The control values ​​are generated by the control device from a desired light distribution, taking into account the optical characteristics of the light sources. This has the advantage that the desired light distribution can be set particularly easily.

[0011] The conversion involves multiplying the light distribution by a conversion function. Once the conversion function has been defined for a specific headlight, a desired light distribution can be easily stored or generated in the control unit, which is then automatically converted into the appropriate control values ​​by multiplying it by the conversion function.

[0012] The conversion function exhibits higher conversion factors for light sources located outside the headlight than for light sources located inside the headlight. This is particularly advantageous because the intensity of the light emitted by external light sources outside the headlight is often lower than the intensity of the light emitted by internal light sources at the same control values. In this description, the terms "outside" and "inside" refer to a radial direction relative to the optical axis of the headlight.

[0013] It is possible to use a characteristic curve when converting the desired light distribution into the control values. Before multiplication, the desired light distribution can be transformed into a corrected desired light distribution using the characteristic curve. For example, the characteristic curve can be designed so that the corrected desired light distribution is adapted to the perception of the human eye. When using the characteristic curve, the term "desired light distribution" can be replaced with the term "corrected desired light distribution" at any point in this description.

[0014] According to one embodiment of the invention, the conversion function can define for each light source a conversion factor by which the respective intensity is multiplied according to the desired light distribution in order to obtain the respective control value.

[0015] According to one embodiment of the invention, the headlight can comprise multiple modules. Each of the modules can comprise multiple light sources. In this case, the desired light distribution can be generated by the multiple modules. The light from different modules can also overlap, at least partially.

[0016] For example, DE 10 2018 130 512 A1 discloses a concept in which a light distribution is generated using multiple modules. This concept is easier to implement if the desired light distribution is defined in the control device and then converted into control values. Based on the desired light distribution, the contributions of the individual modules can be calculated.

[0017] According to one embodiment of the invention, the conversion can take place within the headlight. For this purpose, the headlight can, for example, have a control means. It should be noted that the control means does not have to be arranged in the same housing as the light sources. It is, for example, possible for the control means to be arranged on a different component of the headlight, e.g. on a housing. The conversion within the headlight is advantageous because the headlight can be easily connected to a control device of a motor vehicle. The desired light distribution can thus be easily stored or generated in the control device. This is then converted by the headlight into the corresponding control values. This simplifies assembly in particular when different headlights with different optical properties are used for several motor vehicles of the same model.In this case, only the appropriate conversion function needs to be stored in the headlight control unit to ensure the desired light distribution.

[0018] When defining the desired light distribution, it is possible to select the desired light distribution from several saved light distributions.

[0019] According to one embodiment of the invention, the desired light distribution can be dynamically adapted to a state of the motor vehicle. The term "dynamic" in this description is understood in particular to mean that the process is carried out in real time and the light distribution is, for example, continuously adapted to the state of the motor vehicle. The state of the motor vehicle is understood in particular to mean a speed, a direction of movement, and / or a steering angle of the motor vehicle. The desired light distribution can be adjusted, particularly during cornering, so that the road ahead of the motor vehicle is illuminated as well as possible.

[0020] According to one embodiment of the invention, the light distribution can be converted into exactly one single control value for each of the light sources.

[0021] The system according to claim 7 comprises a control device and a headlight. The control device is designed to control the headlight. The headlight can comprise a control means.

[0022] In particular, it is possible for the control device and the control means to be configured to exchange electronic data with each other. The system is configured to carry out a method according to one embodiment of the invention.

[0023] The motor vehicle according to claim 8 comprises a system according to an embodiment of the invention.

[0024] Further features and advantages of the present invention will become clear from the following description of a preferred embodiment with reference to the accompanying drawings. The same reference numerals are used for identical or similar features and for features with identical or similar functions. Fig. 1A is a schematic graphic representation of a desired light distribution when a motor vehicle is traveling straight ahead; Fig. 1B is a schematic graphical representation of a conversion function; Fig. 1C is a schematic graphic representation of control values ​​for light sources of a headlight to Fig. to produce the light distribution shown in Figure 1A; Fig. 1D is a schematic graphic representation of a headlight using the control values ​​from Fig. 1C generated light distribution; Fig. 2A is a schematic graphic representation of a desired light distribution when cornering the motor vehicle; and Fig. 2B is a schematic graphic representation of the light distribution produced by the headlight.

[0025] In all figures, the light sources of a headlight are plotted on the x-axis. For example, a leftmost light source can be arranged close to the y-axis when the headlight is installed in a motor vehicle, while a rightmost light source is furthest from the y-axis. Neighboring points on the x-axis correspond to neighboring light sources. The course of the respective graph therefore defines a value of the respective parameter for each light source in a light source row of the headlight. It is possible for the headlight to comprise several light source rows arranged one above the other. In this case, a similar or identical graph can be provided for each light source row.

[0026] In Fig. In Figure 1A, the intensity I of the light emitted by the respective light source, measured from outside the headlight, is plotted on the Y-axis. The graph represents a desired light distribution I to be created by the headlight. Light distribution I is characterized by the fact that the light emitted by the central light sources from outside the headlight should have a much higher intensity than the light emitted by the outer light sources. Light distribution I is often advantageous when a motor vehicle is traveling straight ahead, in order to well illuminate the road ahead.

[0027] In Fig. In Figure 1B, a conversion factor EA / I is plotted on the y-axis. The graph represents a conversion function 2 that defines a conversion factor for each light source. Note that a higher conversion factor is defined for the outer light sources than for the center light sources. The shape of the conversion function 2 resembles a cross-section of a bowl with steeply rising edges.

[0028] Conversion function 2 takes into account the optical properties of the headlight that influence the intensity of the light emitted by the light sources measured from outside the headlight. In the illustrated case, the intensity of the light emitted by the external light sources measured from outside the headlight is more attenuated than the intensity of the light emitted by the internal light sources measured from outside the headlight. Therefore, the conversion factor for the external light sources is greater than the conversion factor for the internal light sources. The form of conversion function 2 can be individually adapted to the headlight.

[0029] By multiplying the desired light distribution 1 with the conversion function 2, the Fig. 1C, which defines a control value EA for each light source. This is given as a percentage of the maximum possible power of the respective light source. When the light sources are controlled with these control values, the Fig. 1D shown light distribution 4 on the roadway in front of the motor vehicle, which, with the exception of any inaccuracies due to the calculation of the conversion function 2 and the multiplication of the conversion function 2 with the desired light distribution 1, corresponds to the desired light distribution 1 from Fig. 1A corresponds.

[0030] In Fig. 2A, a desired light distribution 5 is specified, which is also multiplied by the conversion function 2, so that a control value distribution (not shown) is calculated. The control values ​​defined therein for each light source are then used to control the light sources, so that the Fig.2B is created on the roadway in front of the motor vehicle. This is a light distribution that is particularly advantageous when cornering, in order to illuminate the roadway in front of the motor vehicle particularly well.

[0031] For each newly defined desired light distribution, the appropriate control values ​​for the light sources no longer need to be laboriously calculated empirically and / or iteratively. If the desired light distribution needs to be changed, it simply needs to be multiplied by the conversion function 2 calculated once for the headlight, so that the headlight produces the desired light distribution. For example, it is possible for conversion function 2 to be calculated individually for each headlight. However, it is also possible for conversion function 2 to be calculated once for identical headlights and then used for each headlight in series production. With the latter approach, negligible inaccuracies may arise due to production tolerances.

Claims

[1] A method for controlling a headlight of a motor vehicle, the headlight comprising a plurality of light sources, and the method comprising the following steps: - definition of a desired light distribution (1) of the headlight in a control device, wherein the desired light distribution (1) for the light sources each defines a desired intensity of the light emitted by the respective light source to be measured outside the headlight; - Conversion of the desired light distribution (1) into control values ​​for the light sources, taking into account an optical characteristic of the light sources, wherein the conversion comprises a multiplication of the light distribution by a conversion function (2), and wherein the optical characteristic influences the intensity of the respective light source to be measured from outside the headlight; - Control of the light sources with the control values; characterized bythat the conversion function (2) has higher conversion factors for light sources arranged on the outside of the headlight than for light sources arranged on the inside of the headlight, the terms "outside" and "inside" referring to a radial direction with respect to the optical axis of the headlight. [2] Method according to the preceding claim, characterized by that the conversion function (2) defines a conversion factor for each light source, with which the respective intensity is multiplied to obtain the respective control value. [3] Method according to one of the preceding claims, characterized by that the headlight comprises several modules, each of the modules comprising several of the light sources. [4] Method according to one of the preceding claims, characterized by that the conversion takes place within the headlight. [5] Method according to one of the preceding claims, characterized bythat the desired light distribution (1) is dynamically adapted to a state of the motor vehicle. [6] Method according to one of the preceding claims, characterized by that the desired light distribution (1) is converted into exactly one single control value for each of the light sources. [7] System for carrying out a method according to one of the preceding claims, characterized by that the system includes the control device and the headlight. [8] Motor vehicle comprising a system according to the preceding claim.

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