Operating a headlight

Abstract

Control device (10) for a headlight (12), in particular a vehicle headlight, with an adjustable light distribution (34), at least one control unit and at least one object detection unit (24), characterized in that the control device (10) is designed to adjust the light distribution (34) by means of a control in which a detected object (32) is illuminated with a locally varying illuminance, and the control uses as a control variable a contrast between an actively illuminated zone of the detected object (32) and a passively illuminated zone of the detected object (32).

Description

[0001] The invention relates to a control device for a headlight, in particular a vehicle headlight, with an adjustable light distribution, at least one control unit, and at least one object detection unit. The invention further relates to a headlight for a motor vehicle and a motor vehicle. Finally, the invention also relates to a method for operating a headlight, in particular a vehicle headlight, which emits light according to a headlight signal corresponding to an adjustable light distribution, wherein particles and a self-illuminating object are detected by means of a detection unit.

[0002] Control devices for headlights, in particular pixel headlights, as well as methods for their operation, headlights, and also motor vehicles with such headlights are extensively known in the prior art. They serve to illuminate a predetermined area in a predefinable manner, for which purpose a predetermined, in particular adjustable, light distribution is provided. In motor vehicles, they serve in particular to illuminate a roadway as well as to provide the vehicle's own lighting in accordance with regulations. According to the predefinable or adjustable light distribution, the headlight receives a headlight signal by means of which the headlight is controlled according to the light distribution, so that a lighting scheme corresponding to the light distribution is set.Especially with pixel headlights designed for use in motor vehicles, the ability to easily adjust the light distribution as needed has proven advantageous. For example, simply by activating the pixel headlight with a corresponding headlight signal, a low beam or high beam function can be achieved. Of course, the use of pixel headlights is not limited to vehicle headlights; they can also be used in rear lights and / or similar applications.

[0003] A method for controlling the light distribution of a motor vehicle headlight is known, for example, from DE 10 2014 009 254 A1. This addresses the question of adjusting the light distribution in such a way as to prevent the fulfillment of a glare criterion in a specified area. This is intended to prevent drivers of other vehicles from being dazzled and thus avoid creating potentially dangerous situations.

[0004] Furthermore, DE 103 03 046 A1 discloses a method and a device for quantitatively assessing visibility in a motor vehicle for use in fog. The visibility determined therein can be made available for other vehicle functions, preferably transmitted to the driver as information.

[0005] Furthermore, DE 10 2010 048 100 A1 discloses a method for controlling the driving lights of a vehicle with at least two headlights, in which a low beam distribution, a partial high beam distribution and a high beam distribution are set as light distributions.

[0006] Furthermore, DE 10 2015 207 443 A1 discloses a vehicle recognition device comprising an imaging unit and a characteristic area identification unit which identifies two characteristic areas.

[0007] Particularly in the normal operation of motor vehicles, fog has proven to be a disadvantage, as it can significantly reduce visibility. Especially during night driving, the normal operation of vehicle headlights is disadvantageous because the fog creates a baseline brightness in the driver's field of vision, making it difficult to recognize external light sources, such as the taillights of vehicles ahead, self-illuminating traffic signs like traffic lights, and the like. Nevertheless, proper lighting must be maintained in such conditions. Even with a reduced vehicle speed, the aforementioned light sources may only be recognized very late.This is disadvantageous if the driver of the vehicle has to intervene in the vehicle's current driving state due to the detected light source. A similar disadvantage arises, in principle, when operating lighting systems in open areas or outdoor spaces, for example, to illuminate a secured area for surveillance purposes.

[0008] The object of the invention is therefore to improve the visibility of self-illuminating objects in fog, and especially additionally in darkness.

[0009] The invention proposes a control device, a headlight, a motor vehicle and a method according to the independent claims as a solution.

[0010] Further advantageous configurations arise from the characteristics of the dependent claims.

[0011] On the control unit side, for a control unit of this type, it is proposed, in particular as an alternative, that an evaluation unit be configured to determine object position data of the object and, depending on the object position data, an area in which the object is located, when particles and a self-illuminating object are detected by means of a detection unit, wherein the evaluation unit is further configured to generate data for the light distribution depending on the area such that a luminous intensity in the area is reduced or increased compared to a luminous intensity outside this area, and to determine and output the headlight signal accordingly from the data for the light distribution.

[0012] Furthermore, for a control device of this type, it is particularly proposed that the control device be designed to adjust the light distribution by means of a control in which a detected object is illuminated with a locally varying illuminance, and the control uses as a control variable a contrast between an actively illuminated zone of the detected object and a passively illuminated zone of the detected object.

[0013] For example, the control unit can have an evaluation unit with a first sensor connection for a particle sensor for detecting particles and a second sensor connection for an object sensor for detecting a self-illuminating object, wherein the evaluation unit is configured to acquire object position data of the object when particles are detected by means of the particle sensor and when a self-illuminating object is detected by means of the object sensor, and to determine an area in which the object is located depending on the object position data, wherein the evaluation unit is further configured to generate data for the light distribution depending on the area such that a light intensity in the area is reduced or increased compared to a light intensity outside this area, and to determine and output the headlight signal accordingly from the data for the light distribution.The detection sensor does not need to be a two-part device; it can also comprise a single sensor that allows for the detection of both particles and objects. Such a sensor could be a camera or similar device. In this case, the evaluation unit would preferably only require one connection for the detection sensor.

[0014] For a generic headlight, it is particularly proposed that it has a control device according to the invention, wherein the headlight has a pixel-based light source.

[0015] For a motor vehicle of this type, it is particularly proposed that it has a headlight according to the invention and the detection unit for detecting particles and for detecting a self-illuminating object.

[0016] In terms of methodology, it is particularly proposed that, in the case of particles detected by means of the detection sensor and a detected self-illuminating object, object position data of the object and, depending on the object position data, an area in which the object is located are determined, wherein data for the light distribution are generated depending on the area in such a way that a light intensity in the area is reduced or increased compared to a light intensity outside the area, and the headlight signal is determined from the data for the light distribution.

[0017] The invention is based on the understanding that, in the presence of particles such as those found in fog, smoke, snowfall, or the like, especially in combination with darkness, a self-illuminating object is more easily visible when its own illumination is reduced, particularly in a field of view encompassing the area around the object. It is known that particles, especially fog but also dust, snowflakes, or the like, cause their own light to be scattered by the often fine particles, creating stray light that leads to unwanted illumination of the space between the light source and the object. This creates a base brightness that reduces contrast, thus diminishing the visibility of the self-illuminating object.Overall, the contrast between the self-illuminating object and its surroundings is reduced, making it more difficult for the driver to see vehicles ahead, traffic lights, self-illuminating traffic signs, and / or the like. The invention utilizes this by identifying an area around the object, within which the object is located, that is illuminated less intensely, thereby reducing the effect of stray light in this area. This improves the contrast between the self-illuminating object and its surroundings, thus increasing the visibility of the self-illuminating object.

[0018] The self-illuminating object can be, for example, a traffic signal such as a traffic light, a self-illuminating traffic sign, an automatic signaling system, but also headlights of other motor vehicles, in particular headlights, taillights, brake lights, but also reversing lights and / or the like. Furthermore, the self-illuminating object can also be, for example, a warning light in a monitored area, the visibility of which needs to be improved at a monitoring point.

[0019] A headlight is a lighting device used to provide a lighting pattern corresponding to a predetermined, and in particular adjustable, light distribution. Preferably, the headlight is a pixel headlight, which has a light source capable of emitting light in a matrix-like manner, for example, a light source based on a matrix arrangement of light-emitting diodes. Furthermore, the headlight is, for example, a laser headlight, particularly one based on a scanner principle. Due to its properties, the pixel headlight is capable of generating a variety of light distributions by appropriately controlling its light source, for example, in the case of a front headlight for a motor vehicle, low beam, high beam, parking light, and / or the like.

[0020] The invention utilizes a detection sensor for sensing particles. Particles can be dust, ice particles, snowflakes, droplets, especially fog, and / or the like. In particular, the detection sensor can be configured as a particle sensor, a fog sensor for detecting fog, or the like. The detection sensor can provide a particle sensor signal corresponding to the detected particles, which can be further processed by the evaluation unit. Specifically, it can be provided that, in the case of a fog sensor, a fog signal is provided corresponding to the detected fog, which can then be further processed by the evaluation unit. Alternatively, it can be provided that, in the case of a particle sensor, a particle sensor signal is provided, or in the case of a fog sensor, a fog sensor signal is provided, which is first evaluated by the evaluation unit to determine whether particles or fog are present.The detection sensor, in particular the particle sensor or the fog sensor, can be formed, for example, by a camera or the like.

[0021] Accordingly, the invention uses an object signal from the detection sensor to detect the object. The detection sensor can, for example, comprise an object sensor that may include a camera and / or a radar system or device. If a camera is provided, it can also be used as a particle sensor. In this respect, a camera as the detection unit can be used for both particle detection and object detection. Preferably, the detection sensor, in particular the object sensor, is already configured to determine whether the object is self-illuminating. For this purpose, the detection sensor or the object sensor can, for example, comprise a camera system, in particular combined with the radar system. Of course, the object sensor can also transmit its object sensor signal directly to the evaluation unit, which then evaluates the object sensor signal to determine whether a self-illuminating object is present.In principle, the object sensor can also be combined with a database that determines whether the object is self-illuminating. This database could, for example, be that of a navigation device. Furthermore, the database could also be a remote database accessible via a communication link, such as a mobile network, the internet, and / or similar means.

[0022] To enable the headlight to be controlled as desired, the control unit preferably has a headlight connection to which it provides the headlight signal corresponding to the predefined light distribution. The headlight connected to the control unit can then adjust its light source accordingly to produce the predefined light distribution. However, the connection can also be implemented via a bus system, such as a CAN bus or similar in a motor vehicle. This principle also applies to the detection unit, which can likewise be connected to the control unit via the bus system. This reduces the number of required connections.

[0023] The process according to the invention can preferably be achieved by means of an evaluation unit that is included in the control unit. For this purpose, the evaluation unit preferably has a first sensor connection for the particle sensor and a second sensor connection for the object sensor. This provides the evaluation unit with sensor signals from the detection sensor, in particular the particle sensor and the object sensor. Alternatively or additionally, a connection via the BUS system can also be provided. In this case, the evaluation unit and the detection sensor are each connected to the BUS system.

[0024] The evaluation unit is further configured to acquire object position data for particles detected by the detection sensor or particle sensor and for a self-illuminating object detected by the detection sensor or object sensor. The object position data can be, for example, a geographical position, such as one based on three-dimensional spatial coordinates or the like. Preferably, the evaluation unit is configured to determine the object position data only if both particles and a self-illuminating object have been detected. If the object is not self-illuminating, for example, it may be provided that object position data is not determined.

[0025] Furthermore, the evaluation unit determines an area within which the object is located, based on the object's position data. This area can be, for example, a solid angle, a space encompassing the object, and / or the like. Preferably, the area is larger than the object so that the object is covered by the area as completely as possible. The area can be configured to maintain a specific, predefined distance from the object. This distance can be adjustable. The evaluation unit determines corresponding area data that characterizes the area. For example, the area data can consist of an angle specification of the solid angle in conjunction with a direction specification, which can be determined from the object's position data.

[0026] The evaluation unit is further configured to generate the data for the light distribution based on the area data. For this purpose, appropriate data processing can be provided, which can be carried out, for example, by means of a hardware circuit and / or a computer unit controlled by a suitable computer program. The evaluation unit generates the data for the light distribution such that the luminous intensity within the area is reduced or increased compared to the luminous intensity outside the area, which serves as the reference luminous intensity. The reference luminous intensity is preferably the luminous intensity that would be determined by the control device if no particles and / or no self-illuminating object were detected. For example, the luminous intensity within the area can be reduced. This reduces effects due to stray light in order to improve the contrast for detecting the self-illuminating object.Under certain circumstances, an improvement in contrast can also be achieved by increasing the light intensity in the area.

[0027] From the light distribution data, the evaluation unit then determines the corresponding headlight signal, which is output, for example, at the headlight connection or to the BUS system. The headlight signal can be analog or digital. A coded digital signal, containing detailed data regarding the headlight's light distribution settings, can be particularly advantageous. In this case, the headlight signal corresponds to the predefined light distribution.

[0028] Furthermore, the control device can be configured to adjust the light distribution by means of a control mechanism in which a detected object is illuminated with a locally varying illuminance. The control mechanism uses the contrast between an actively illuminated zone of the detected object and a passively illuminated zone as its controlled variable. The control mechanism can be implemented by an electronic circuit, which may include a computing unit such as a microprocessor or the like. Preferably, the actively illuminated zone can define the area, thereby also determining the passively illuminated zone. An image is optically captured by the camera as a detection sensor, and the contrast between the zones is calculated from this image. The control mechanism is configured to maximize the contrast.For this purpose, the headlight provides a locally varying light distribution, which is continuously adjusted during the regulation process until the contrast is maximized.

[0029] It proves particularly advantageous if the area is determined based on a predefined geometric shape. For example, a geometric shape such as a circle, ellipse, rectangle, square, or similar can be provided to define the area, ensuring that, with appropriate dimensions, its geometric properties allow it to enclose the object as completely as possible. Therefore, it is not necessary to determine complex geometries for the areas. Simple shapes can be used, thus reducing the effort required to define the area.

[0030] According to one embodiment, it is proposed that the rear lights of a preceding vehicle be detected as the object. This would allow for safer driving in poor visibility conditions caused by particles such as fog or similar, because the improved visibility provided by the rear lights would allow the driver of the following vehicle to better judge the distance to the vehicle in front.

[0031] According to the invention, the object used is the license plate of the vehicle ahead. This also improves safety because it further enhances the estimation of the distance to the vehicle ahead.

[0032] Furthermore, it proves advantageous to determine a visibility range and to select the size of the area based on this range. This design allows the area to be chosen to be only as large as necessary for the intended function of the invention. For example, it can be provided that in light fog and moderately reduced visibility, a small area is determined that surrounds the object at a short distance, whereas in heavy fog and low visibility, a larger area is provided that takes into account the increased effect of scattered light in heavy fog. This ensures that the intervention by the invention during intended lighting operation is only as strong as necessary. The lighting function to be achieved by the headlight is thus hindered as little as possible.

[0033] According to a further embodiment, it is proposed that the reference luminous intensity be a luminous intensity determined according to a light distribution without particles or fog. This reference luminous intensity can, for example, be a predefined value or a predefined data set in the control unit for the intended operation of the headlight in the absence of particles, particularly fog, in conjunction with a self-illuminating object. This value or data set can, for example, be preset at the factory. Alternatively, the control unit can receive the value or data set for the reference luminous intensity from a higher-level control system, particularly a higher-level vehicle control system. This makes it possible to configure the reference luminous intensity for each individual vehicle.However, it is also possible for the reference luminous intensity to be provided by the headlight itself. Specifically, the reference luminous intensity can be individually configured for each headlight. This ensures that, even during maintenance, such as headlight replacement, the headlight always provides the necessary light emission to reliably fulfill its intended lighting function. When replacing a headlight, it may be necessary to adjust the reference luminous intensity value or data set to the characteristics of the new headlight's light source, particularly if the control unit is separate from the headlight and is not replaced. Overall, this results in a simple and reliable provision of the reference luminous intensity.

[0034] Furthermore, it is proposed that the light intensity be varied in a pulsating manner. This design is particularly advantageous when combined with increasing the light intensity relative to the reference luminous intensity. By pulsating the light intensity, not only can contrast be increased, but the driver's attention can also be drawn precisely to this area. This can improve the overall visibility of the self-illuminating object for the driver of the motor vehicle.

[0035] Furthermore, it may be provided that the pulse shape and / or pulse frequency of the pulsating change in light intensity is varied. For example, the pulse shape and / or pulse frequency may be adjusted depending on the viewing distance. Alternatively, the pulse shape and / or pulse frequency may be adjusted depending on the distance between the self-illuminating object and the pixel headlight or the vehicle. It may also be provided that the pulse amplitude and / or pulse frequency increases with decreasing distance. In addition, it may be provided that the pulse shape and / or pulse frequency is selected in such a way as to improve visibility by utilizing ergonomic effects based on the physical properties of the human eye.For this purpose, pulse shapes such as square, triangle, sine, sawtooth, and / or similar can be used or combined. Furthermore, the frequency can be adjusted to improve visibility. The pulse frequency can vary, for example, from approximately 0.1 Hz to approximately 50 Hz. A pulse frequency of approximately 0.1 to approximately 1.5 Hz can be particularly advantageous.

[0036] It is particularly advantageous if the pulsating change in light intensity includes a burst pulse. The burst pulse can consist of a time-spaced sequence of several very short individual pulses, which are also very closely spaced between each other, for example, approximately 0.5 s or less. The time interval between such burst pulses can be chosen to be in the range of more than approximately 0.5 s, in particular from approximately 1 s to approximately 5 s; in particular, the time interval can be dependent on a spatial distance. This can achieve an improved effect or adaptation with regard to the detectability of the self-illuminating object, especially a warning function.

[0037] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0038] This shows: Fig. 1 A schematic representation of a control device according to the invention with a pixel headlight of a motor vehicle in intended operation; Fig. 2 A schematic representation of a driver's field of vision when driving in fog in the dark using the invention according to Fig. 1; and Fig. 3 A schematic representation of a motor vehicle CAN bus according to Fig. 2, to which the headlight, the control unit, a camera and a radar sensor are connected.

[0039] Fig. Figure 1 shows a schematic diagram of a control unit 10 according to the invention for a pixel headlight 12. The pixel headlight 12 is, in this case, a front headlight of a motor vehicle (not shown), which, together with the control unit 10, forms a headlight assembly. The pixel headlight 12 emits light according to a headlight signal 14 corresponding to a predefinable light distribution 34. In this case, the control unit 10 is configured to output the headlight signal 14 corresponding to the predefinable light distribution 34 at the headlight connector 16.

[0040] The pixel headlight 12, which in this case comprises a laser scanner as a pixel-based light source 38, is connected via a connection 36 to the headlight connection 16 of the control unit 10. In accordance with the headlight signal 14, the laser scanner 38 generates a light distribution 34 to illuminate the vehicle's path.

[0041] The control unit 10 comprises an evaluation unit 18, which in this case is formed by an electronic circuit with a program-controlled computer unit of the type of a microprocessor. The evaluation unit 18 has a first sensor connection 20 for a fog sensor 24 as a particle sensor or as a detection sensor for detecting fog 40. The fog sensor 24 is in this case formed by a camera.

[0042] Furthermore, the evaluation unit 18 has a second sensor connection 22 for an object sensor 26, or as a detection sensor for detecting a self-illuminating object 32. In this case, the object sensor 26 is a radar device. The radar device also includes an optical unit that can detect whether the object 32 is self-illuminating. In this case, the object 32 is a reversing light of a vehicle 28 traveling ahead.

[0043] The evaluation unit 18 is designed to acquire object position data of object 32 when fog 40 is detected by the fog sensor 24 and a self-illuminating object 32 is detected by the object sensor 26. For this purpose, the signal from the object sensor 26 is further evaluated to determine spatial position coordinates.

[0044] Depending on the recorded object position data, the evaluation unit 18 determines an area 30 in which the object 32 is located, as well as area data corresponding to area 30. The area data also includes spatial position data, which, however, define a position and an extent of the area. In this case, area 30 is formed by the shape of a rectangle, which includes the object 32, here the two taillights of the preceding vehicle 28, as well as a license plate of the preceding vehicle 28 arranged between the taillights ( Fig. 2) The area 30 is thus formed by a solid angle which, at the position of object 32, provides the rectangular shape that encloses or encompasses object 32.

[0045] The evaluation unit 18 is further configured to generate the data for the light distribution 34 based on the area data such that the luminous intensity in area 30 is reduced compared to a reference luminous intensity. From this, the evaluation unit 18 determines the corresponding headlight signal 14, which is output at the headlight connection 16 for the pixel headlight 12. The pixel headlight 12 receives the headlight signal 14 and adjusts its laser scanner 38 to generate the specified light distribution 34, which exhibits reduced luminous intensity in area 30.

[0046] By reducing the light intensity in area 30, less stray light is generated by the fog 40, making the self-illuminating rear light 32 more visible to the driver of the vehicle, in this case, the following vehicle. The invention thus increases contrast.

[0047] The present invention provides that the area 30 is determined based on the geometric shape of a rectangle. This defines the area 30 as a solid angle within which the pixel spotlight 12 emits only reduced light. The result of this inventive principle shows Fig. 2, which shows a representation from the perspective of the driver of the motor vehicle in darkness and fog 40.

[0048] It can be seen that the pixel headlight 12 is controlled such that a reduced light emission occurs in area 30. This ensures that the taillights 32 of the preceding vehicle 28, as well as its license plate, can be clearly seen despite the fog 40. Although the preceding vehicle 28 would otherwise be difficult to see, the taillights 32 are reliably visible. The invention achieves this by providing the light distribution 34.

[0049] The invention thus achieves the exclusion of areas of self-illuminating objects, such as self-illuminating signs, traffic lights, and the like, from the light distribution 34 emitted by the pixel headlight 12. This reduces stray light and thus glare in this area 30, while simultaneously increasing contrast. Consequently, such objects 32 can be recognized more easily and at an earlier stage by the driver of the motor vehicle.

[0050] Alternatively, it is also possible to highlight object 32 by slightly pulsing the light intensity provided in area 30 by pixel spotlight 12.

[0051] The pixel headlight 12 is particularly preferred as a high-resolution headlight, for example, an HD pixel headlight. These are especially suitable for use in the invention because they can project particularly detailed individual light distributions 34 onto the road and can darken or brighten self-illuminating objects within a narrow range.

[0052] Overall, the invention makes it possible to achieve improved contrast between self-illuminating objects and ambient light in fog. Furthermore, it enables better and earlier detection of self-illuminating objects.

[0053] Fig.Figure 3 shows a schematic block diagram illustrating an alternative connection of the camera 24, the radar sensor 26, the control unit 10, and the headlight 12 to a CAN bus 42 of the vehicle. This enables a communication link between the aforementioned units via the CAN bus 42. Therefore, no additional separate lines and connections are required.

[0054] The exemplary embodiment serves only to illustrate the invention and is not limiting to it. In particular, corresponding process features can be provided for device features and vice versa.

Claims

[1] Control device (10) for a headlight (12), in particular a vehicle headlight, with an adjustable light distribution (34), at least one control unit and at least one object detection unit (24), characterized by , that the control device (10) is designed to adjust the light distribution (34) by means of a control in which a detected object (32) is illuminated with a locally varying illuminance, and the control uses as a control variable a contrast between an actively illuminated zone of the detected object (32) and a passively illuminated zone of the detected object (32). [2] Headlight for a motor vehicle with a control device (10) according to claim 1, wherein the headlight (12) has a pixel-based light source (38). [3] Motor vehicle with the headlight according to claim 2, the detection unit (24, 26) for detecting particles (40) and for detecting a self-illuminating object (32). [4] Motor vehicle according to claim 3, characterized by , that the detection unit (24, 26) includes a camera, in particular a rain sensor. [5] Motor vehicle according to claim 3 or 4, characterized by , that the detection unit (24, 26) has a radar device. [6] Method for operating a headlight (12), in particular a vehicle headlight, which emits light according to a headlight signal (14) corresponding to an adjustable light distribution (34), wherein particles (40) and a self-luminous object (32) are detected by means of a detection unit (24, 26), wherein object position data of the object (32) and, depending on the object position data, an area (30) in which the object (32) is located are determined for particles (40) and a detected self-luminous object (32), wherein data for the light distribution (34) are generated depending on the area such that a luminous intensity in the area (30) is reduced or increased compared to a luminous intensity outside the area (30), and the headlight signal (14) is determined from the data for the light distribution (34). characterized by, that the object (32) is a license plate of the motor vehicle (28) driving ahead. [7] Method according to claim 6, characterized by , that the area (30) is determined based on a given geometric shape. [8] Method according to claim 6 or 7, characterized by , that the object (32) is the rear lights of a motor vehicle (28) traveling ahead. [9] Method according to any one of claims 6 to 8, characterized by , that the light intensity in area (30) is changed in a pulsating manner.

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