Method for controlling a vehicle headlight and headlight system

Abstract

Method for controlling a headlight (4) of a vehicle, comprising: Activating the headlight (4); Check whether a control signal (5) from a control unit (3) to generate a second light field (6) by means of the headlight (4) is present at the headlight (4); when the control signal (5) is applied to the headlight (4), the second light field (6) is generated according to the control signal (5) by means of the headlight (4); if the control signal (5) for generating the second light field (6) is not present at the headlight (4): Generating a first light field (7) using the headlight (4); Check whether the control signal (5) from the control unit (3) to generate the second light field (6) is present at the headlight (4); Comparing a light field parameter of the first light field (7) with a light field parameter of the second light field (6); Calculating a dimming ramp based on the comparison performed, if the difference between the light field parameters is above a predetermined parameter, and activating the second light field (6) using the calculated dimming ramp; and Otherwise, the second light field (6) is generated according to the control signal (5) by means of the headlight (4).

Description

[0001] The present invention relates to a method for controlling a headlight of a vehicle and a corresponding headlight system having at least one headlight, wherein the headlight in particular has a headlight based on an LED matrix.

[0002] One of the risk factors that has a major influence on road traffic accidents is poor or inadequate illumination of the vehicle's surroundings, particularly the road ahead. This is not surprising when you consider that drivers rely almost exclusively on visual perception of their surroundings. The use of modern headlights based on LED technology makes it possible to optimally illuminate the vehicle's surroundings. The light field generated by the headlight system can be adapted to the respective driving situation. By recording the vehicle's surroundings using a camera, the generated light field can be shaped in such a way that other vehicle users are not dazzled and their perception of their surroundings is not impaired.

[0003] Modern LED matrix headlights today feature up to 84 light-emitting diodes per headlight, arranged in a predefined arrangement of rows and columns. An LED matrix headlight offers very high luminosity, which can be spatially distributed on a fine scale, for example, to avoid dazzling drivers in oncoming vehicles, as already mentioned. This functionality is made possible by the interaction of the headlight system with a camera, such as the vehicle camera, which is usually located in the vehicle's interior mirror. Each individual diode is electronically controlled individually by the control unit, and its brightness is adjusted so that when an oncoming vehicle or vehicle ahead is detected, the driver is not affected by the light field emitted by the headlight system.In addition to selectively masking out oncoming and preceding vehicles, highly reflective traffic signs can also be masked out in segments to avoid dazzling the driver.

[0004] The functionalities described above are all based on the control unit controlling the individual LEDs within the high-resolution LED matrix of each of the two headlights, optimally adapted to the vehicle environment reconstructed by a camera. In various situations, however, it can happen that the high-resolution headlight is activated and independently generates a light field without receiving a control signal from the control unit, which is equipped with a video processing function. This can be due, for example, to the control unit requiring longer to boot up than the time required to activate the LED elements in the LED matrix headlight after it has been activated. As soon as the control unit transmits a corresponding control signal to the LED matrix headlights, according to which a light field adapted to the detected vehicle environment is to be generated, this signal is accepted and implemented by the headlight system.If there is a strong deviation between the autonomously generated light field and the light field generated by the headlight in accordance with the control signal from the control unit, this can lead to flickering in the light image that is disturbing from the driver's perspective.

[0005] US 10,317,034 B2 discloses a motor vehicle headlight with adaptive high beam, comprising a housing, a digital camera, a control unit, and a segmented illumination array, wherein the digital camera is integrally formed with the headlight. The digital camera captures an image of the surroundings in front of the vehicle, and the control unit detects objects within the image and generates a control signal based at least partially on a position of the objects. The segmented illumination array is arranged within the housing and includes a plurality of solid-state light sources. The driver selectively controls the solid-state light sources based on the control signal from the control unit.

[0006] Against the background of the prior art, it is an object of the present invention to provide a method for controlling a segmented headlight system of a vehicle, by means of which flicker-free switching between different light fields generated by the headlight system can be achieved. A segmented headlight is understood to mean, in particular, an LED matrix headlight and, in general, a headlight that has a number of individually controllable light sources, for example, LEDs or OLEDs, arranged in a predetermined pattern.

[0007] To achieve the above-mentioned object, a method for controlling a headlight system with the features of independent patent claim 1 is provided. Further embodiments can be found in the dependent claims.

[0008] According to the invention, a method for controlling a headlight is provided, wherein the headlight preferably has at least one segmented headlight. In particular, the method can correspond to a method for controlling a headlight system of a vehicle, wherein the headlight system has two headlights, each headlight having a corresponding control device. Alternatively, the headlight system can have one control device that controls both headlights. In the following, the description of the method according to the invention is limited to one headlight without restricting its generality.

[0009] The method according to the invention initially comprises the step of activating the headlight. This can mean the manual switching on of the vehicle's headlights by the driver or the automatic switching on of the headlights based on a corresponding signal, which is based on monitoring the brightness of the vehicle's surroundings (e.g., using the vehicle's camera).

[0010] The method according to the invention further includes checking whether a control signal from a control unit for generating a second light field by means of the headlight is present at the headlight. This check can be performed at the moment the headlight is activated.

[0011] In a first case, in which a control signal for generating the second light field is applied to the headlight, the method according to the invention comprises generating the second light field according to the control signal by means of the headlight. The second light field can be a light field that dynamically adapts to the vehicle's surroundings. For this purpose, the control signal can be generated based on an evaluation of the video signal from the vehicle camera. In principle, the second light field can correspond to a high beam or low beam that is individually adapted to the driving environment. The control signal for generating the second light field can be generated based on a GMSL signal (GMSL: Gigabit Multimedia Serial Link) or correspond to this.

[0012] In a second case, in which the control signal for generating the second light field is not applied to the headlight, the method according to the invention comprises generating a first light field by means of the headlight. The first light field can correspond to a standard light field, for example a standard high beam or low beam, which, in particular in contrast to the second light field, is not adapted to the vehicle surroundings, but is generated by default in the absence of information regarding the vehicle surroundings. The first light field can be generated by applying a standard control signal to the headlight. Alternatively, if the control signal for generating the second light field is not applied to the headlight, the first light field can be generated automatically by the headlight, for example immediately after activation.

[0013] In the second case, the method according to the invention further comprises checking whether the control signal from the control unit for generating the second light field is present at the headlight.

[0014] In the second case, the method according to the invention further comprises comparing a light field parameter of the first light field with a light field parameter of the second light field. In this step, the second light field is not yet generated by the headlight, but rather, initially, only its configuration according to the control signal is compared with the configuration of the actually generated first light field.

[0015] In the second case, the method according to the invention further comprises calculating a dimming ramp based on the comparison performed if the difference between the light field parameters is above a predetermined parameter, and activating the second light field using the calculated dimming ramp. The dimming ramp can be a control signal that causes the second light field to be switched on with a time delay or switched on (connected) for a certain period of time, with the first light field being switched off at the same time. The dimming ramp is therefore only calculated and used when the difference between the two light fields is sufficiently large. Furthermore, the ramp is always generated as a function of the difference between the first light field and the second light field.

[0016] Activating the second light field according to the calculated dimming ramp can involve the LED elements of the segmented headlight, also referred to as pixels, not being switched instantaneously to their brightness resulting from the configuration of the second light field, but rather this priority occurring on a predetermined timescale – according to the dimming ramp. In other words, the state of the LED elements can be gradually adjusted so that after a certain period of time, the cumulative light emission of the LED elements no longer corresponds to the first, but rather to the second light field. The transition can occur "smoothly" or continuously by gradually changing the states of the corresponding LED elements (e.g., dimming each of the corresponding LED elements up or down from a first brightness value to a second brightness value).According to various embodiments of the method according to the invention, the switching of a state of each of the corresponding LED elements can be carried out with its own time constant. Furthermore, corresponding LED elements can be combined into groups, and each group can be adjusted with its state using an individual time constant.

[0017] Otherwise, i.e., if the difference between the two light fields is not sufficiently large, the method according to the invention comprises, in the second case, generating the second light field according to the control signal by means of the headlight. In this case, no dimming ramp is used, since the switching from the first light field to the second light field can occur instantaneously.

[0018] The method according to the invention can be understood as a handshake process between the control unit with video processing function and the high-resolution headlight. If the second light field differs from the first light field, the method according to the invention provides for a crossfade of the first light field with the second light field, with the dimming ramp defining a crossfade scenario (transition scenario).

[0019] In further embodiments of the method according to the invention, the first light field can correspond to a standard light field generated by the headlight without knowledge of the vehicle's surroundings. The first light field can thus correspond to a factory-predefined standard light field that is not adjusted during driving based on the camera data.

[0020] In further embodiments of the method according to the invention, the second light field can correspond to a light field that is situationally adapted to the vehicle's surroundings and generated based on the control signal from the headlight. The second light field can thus be characterized by being dynamically adapted to the vehicle's surroundings while driving. The adaptation can be achieved by means of the appropriately configured control signal.

[0021] In further embodiments of the method according to the invention, the control signal for generating the second light field can be generated based on a camera recording the vehicle's surroundings. The vehicle electronics can be configured to reconstruct the vehicle's surroundings and, based on this, adapt the light field as needed. Based on this, the control signal for generating the second light field can be adapted accordingly. Depending on the electronics used, the second light field can be adapted at a frequency in the range of a few tens to a few hundred Hz.

[0022] In further embodiments of the method according to the invention, the light field parameter can correspond to a brightness of the respective light field. Consequently, the comparison of the two light field parameters of the light fields can involve comparing the brightnesses, for example, the average brightnesses of the two light fields. For example, the average of the brightness values ​​of all pixels of the high-resolution headlight can be calculated for the configurations of the two light fields and compared with each other.

[0023] In further embodiments of the method according to the invention, activating the second light field can involve switching from the first light field to the second light field. As already mentioned, this switching can occur gradually according to the dimming ramp, so that the first light field is dimmed down to a zero brightness value according to a first characteristic curve, and the second light field is dimmed up to a desired brightness value according to a second characteristic curve.

[0024] According to the invention, a headlight system for a vehicle is further provided, which has at least one headlight and at least one control unit for controlling the headlight, wherein the headlight system is configured to carry out the method described herein.

[0025] The features mentioned above and those to be explained below can be used not only in the combination specified but also in other combinations or on their own without departing from the scope of the present invention.

[0026] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. Fig. Figure 1 shows a diagram illustrating the initial scenario underlying the method according to the invention. Fig. 2 shows a flow chart illustrating an embodiment of the method according to the invention. Fig. 3 shows an exemplary dimming ramp which can be used in the context of the method according to the invention.

[0027] In Fig. 1 shows a diagram illustrating the scenario underlying the method according to the invention. On the left side of the diagram, a vehicle headlight 1 is illustrated, which has a control unit 3 and a high-resolution headlight 4. The control unit 3 transmits a control signal 5 to the headlight 4, by means of which the light field generated by the headlight 4 is configured. By means of the control signal 5, the headlight 4 is controlled to emit a second light field 6, which is dynamically adapted to the currently prevailing driving environment. The commissioning of the control unit 3 or its activation takes place on a first time scale T1. This means that from the activation of the control unit 3, a time period usually T1 elapses until the control unit 3 can provide the control signal 5 to the headlight 4 so that the headlight 4 generates the second light field 6.

[0028] When the headlight 4 is switched on together with the headlight system 1, it can emit light immediately. At the start of light emission, there is no control signal 5 for generating the second light field 6 at the headlight 4. Therefore, the headlight 4 automatically generates a standard first light field 7 that is not adapted to the driving environment, as long as the control signal 5 for generating the second light field 6 is not applied to the headlight 4. The vehicle environment illuminated by the headlight 4 of the vehicle is identified by reference numeral 2. As soon as the control signal 5 is present, it is possible to switch from the first light field 7 to the second light field 6. In the prior art, this switching from the first light field 7 to the second light field 6 usually takes place instantaneously.In other words, the second time T2, which characterizes the switching process from the first light field 7 to the second light field 6, is essentially zero or is limited by the signal processing speed of the electronics. The present invention addresses this point and optimizes this switching process so that no flickering occurs during switching between the two light fields 7, 6.

[0029] In Fig. 2 shows a flowchart illustrating an embodiment of the method according to the invention. At the beginning of the method, the method comprises the first step 10 of activating the headlight 4. Thereafter, in a step 12, the method comprises checking whether the control signal 5 from a control unit 3 for generating the second light field 6 by means of the headlight 4 is present at the headlight 4. If the control signal 5 is present at the headlight 4, step 18 follows, which comprises generating the second light field 6 according to the control signal 5 by means of the headlight 4. This case occurs when, upon switching on the headlight 4, the control unit 3 can immediately provide a control signal 5. Otherwise, i.e., if the control signal 5 for generating the second light field 6 is not yet present at the headlight 4, step 13 follows, which comprises generating the first light field 7 by means of the headlight 4.This is followed by step 14, which involves checking whether the control signal 5 for generating the second light field 6 is present at the headlight 4. If the control signal 5 is not present, the method returns to step 13, or the first light field 7 continues to be generated. These two steps represent a continuous loop. The continuous loop is only exited when the control signal 5 for generating the second light field 6 is applied to the headlight 4. If this is the case, step 15 follows, which involves comparing a light field parameter of the first light field 7 with a light field parameter of the second light field 6. If the two light field parameters are equal, or if the difference between the two light field parameters is below a predetermined threshold value, step 18 follows, which involves generating the second light field 6. This transition corresponds to an instantaneous switching between the two light fields 7, 6.If the two light fields 7, 6 differ significantly, i.e., if the difference between the two light field parameters is above a predetermined threshold, the method comprises, in a further step 16, calculating a dimming ramp based on the comparison performed. This is followed by step 17, which comprises activating the second light field 6 using the calculated dimming ramp. After completion of this step 17, step 18 follows or is initiated, which comprises generating or emitting the second light field 6.

[0030] Fig. 3 shows a diagram 30 illustrating an exemplary dimming ramp that can be used within the scope of the method according to the invention. In the diagram 30, time is plotted on the x-axis 31 and intensity is plotted on the y-axis 32. A first characteristic curve 33 describes the intensity profile of the first light pattern 7, and a second characteristic curve 34 describes the intensity of the second light pattern 6. As shown, the continuous or gradual switching from the first light field 7 to the second light field 6 takes place between the initial time T A and the end time T B . The difference between these two times T A , T B corresponds to the second time scale T2 in Fig.1. During this time, the intensity of the first light pattern 7 is dimmed from its full intensity to zero according to the first characteristic curve 33. During this time, the intensity of the second light pattern 6 is simultaneously dimmed from zero to its full intensity according to the second characteristic curve 34. This also includes cases in which some pixels experience little or no change in their intensity because they are activated in both light patterns 6, 7. Furthermore, it should be noted that the second characteristic curve 34, which characterizes the intensity of the second light field 6, does not necessarily have to rise to the maximum intensity level (100%). Depending on the situation, it may also arise that the second light field 6 is switched to a fraction of the full intensity, for example 80%. In general, the course of the first characteristic curve 33 and the second characteristic curve 34, in particular the position of the start and end point T A , TB on the time axis 31 depends on the configurations of the two light fields 6, 7.

Claims

[1] Method for controlling a headlight (4) of a vehicle, comprising: Activating the headlight (4); Checking whether a control signal (5) from a control unit (3) for generating a second light field (6) by means of the headlight (4) is present at the headlight (4); when the control signal (5) is applied to the headlight (4), generating the second light field (6) according to the control signal (5) by means of the headlight (4); if the control signal (5) for generating the second light field (6) is not applied to the headlight (4): Generating a first light field (7) by means of the headlight (4); Checking whether the control signal (5) from the control unit (3) for generating the second light field (6) is present at the headlight (4); Comparing a light field parameter of the first light field (7) with a light field parameter of the second light field (6); Calculating a dimming ramp based on the comparison performed if the difference between the light field parameters is above a predetermined parameter, and activating the second light field (6) using the calculated dimming ramp; and otherwise, generating the second light field (6) according to the control signal (5) by means of the headlight (4). [2] Method according to claim 1, wherein the first light field (7) corresponds to a standard light field generated by the headlight (4) without knowledge of the surroundings of the vehicle. [3] Method according to claim 1 or 2, wherein the second light field (6) corresponds to a light field which is situationally adapted to the surroundings of the vehicle and which is generated on the basis of the control signal (5) from the headlight (4). [4] Method according to one of claims 1 to 3, wherein the control signal (5) for generating the second light field (6) is generated on the basis of a detection of the surroundings of the vehicle by means of a camera. [5] Method according to one of claims 1 to 4, wherein the light field parameter corresponds to a brightness of the respective light field (6, 7). [6] Method according to one of claims 1 to 5, wherein activating the second light field (6) comprises switching from the first light field (7) to the second light field (6). [7] Headlight system (1) for a vehicle, comprising at least one headlight (4) and at least one control unit (3) for controlling the headlight (4), wherein the headlight system (1) is configured to carry out the method according to one of claims 1 to 6.

Images