Vehicle headlights including a switching system

Description

[0001] The invention relates to a vehicle headlight according to the subject matter of claim 1.

[0002] In recent decades, lighting technology has been dominated by light sources in the form of fluorescent lamps or incandescent lamps. Incandescent lamps could be manufactured much more compactly than fluorescent lamps, making them particularly suitable for use in optical systems where a defined, precisely determined light distribution is required. Such optical systems include, for example, vehicle headlights, which emit low beam, high beam, and other specific light distributions.

[0003] In vehicles, these incandescent lamps are typically powered via relays embedded in a circuit and connected in series with the lamps. These relays can be activated and deactivated by manually and / or automatically switchable controls. These components can be part of a lamp control unit.

[0004] Incandescent light bulbs have a limited lifespan, which is usually significantly shorter than the lifespan of the product in which the bulb is used. Therefore, the bulbs must be replaced regularly. A bulb typically fails due to a break in the filament, interrupting the flow of current through the bulb. To detect a bulb failure as quickly as possible, lamp control units often have current detection capabilities. These units monitor the current drawn by the bulb to determine its functionality. If the current falls below a predefined minimum value despite the circuit being active, a bulb failure is detected, and a fault sequence is triggered.This established technique therefore functions like a digital system, in which only two states are differentiated based on clearly distinguishable signals: If a sufficiently high current is drawn when the circuit is activated, it is assumed that the lamp is working. If, on the other hand, no current is drawn, the lamp has failed.

[0005] The advancement of light sources from incandescent lamps to even more compact and durable semiconductor components has led to the widespread replacement of incandescent lamps in modern lighting devices. Typically, an incandescent lamp can be replaced by any number of semiconductor light sources, especially LEDs. While these components have a significantly longer lifespan, individual components can still fail for various reasons. This means that a modern lighting device, which now incorporates a multitude of individual light sources, typically does not fail entirely, but rather only individual light sources may fail.It can therefore happen that a modern lighting device, despite defective individual LEDs, continues to draw current at a level that would be classified as normal operating current by a conventional lamp control unit (see e.g. ). Figure 3 , Section A). On the other hand, it can also happen that the large number of individual light sources in a modern lighting device is used to create lighting effects, which are achieved by selectively switching the individual light sources on and / or off, and thus different current consumption occurs at different times even during normal operation.

[0006] Conventional lamp control units (LCUs) do not adequately address this issue, as they fundamentally require binary operating behavior to distinguish between function and failure. Documents US 2012074856 A1 and US 7276861 B1 disclose driver circuits for light sources. Document DE 10107578 A1 discloses a lighting system for motor vehicles. Document DE 102015201739 A1 discloses a vehicle light comprising two lighting units.

[0007] One object of the invention is therefore to create a vehicle headlight comprising a circuit system with which modern light modules comprising a number of light sources can be supplied and at the same time the functionality of the light sources can be monitored.

[0008] This problem is solved with a vehicle headlight according to the subject matter of claim 1.

[0009] In this way, it is possible to use modern lighting modules with a number of light sources in conjunction with conventional lamp controllers. The total current consumption of the light sources in the module, which now no longer simply fluctuates between two states (on / off) but can exhibit further levels through the switching on and off of individual light sources, can be supplemented by the use of the controllable device. This allows the lighting module to behave like a classic "binary" incandescent lamp module with regard to fault detection by the conventional lamp controller. In particular, the microcontroller can be configured not only to detect the operating state of the light sources but also to control the operating state of the light sources themselves.

[0010] The lamp control unit is configured to supply an operating voltage and current to the light module and is connected to the light module. The microcontroller can be put into a power-saving mode during periods when no intervention by the auxiliary device is required. The microcontroller is designed to individually detect and monitor the operating status of each light source.

[0011] In this disclosure, unless otherwise specified, the term "a number of" means a number that may be, for example, two, three, four or more, in particular six, eight, ten, twelve, twenty or more than twenty. A person skilled in the art can select the number of each light source according to the light distribution and / or light function to be emitted.

[0012] In particular, the fault routine may include switching off the light module and / or outputting a fault signal.

[0013] Furthermore, it may be provided that the controllable aid is designed to switch off the supply to the electric light sources if the detected operating state deviates from a target state derived from the comparison information, so that the current drawn falls below the lamp control unit threshold and the lamp control unit infers the presence of a fault.

[0014] In particular, the device may be designed to switch off all individual light sources as a whole.

[0015] Furthermore, the device may be configured to connect a current sink. According to the invention, the device comprises a current sink, and the current sink is designed as an electrical load in the form of an ohmic resistor, in particular an ohmic resistor connected in parallel with the light sources. In this way, the current consumption of the light module can be easily increased if, for example, the current consumption by the light sources is low during a chasing light effect.

[0016] In particular, the comparison information may include a continuous operating threshold that is above the lamp control unit threshold. This comparison information may also include a representation of an animation signal, which relates to an animation in the form of a temporal sequence of switching on and / or off the individual light sources, especially for generating a chasing light effect. From this, the temporal sequence of the current consumption of the light sources of the light module can be derived. The controllable device includes a current sink and is controlled by the microcontroller in such a way that, during the animation, the continuous operating threshold is not undercut by selectively switching on the current sink, even if individual light sources are deactivated for animation purposes. In this way, a conventional "binary" lamp control unit can continue to be used, even if lighting effects such as...Chasing light effects are implemented by the light module, causing the current draw of the light sources to fluctuate. The current sink can remain active until the lighting effect is complete. As a further development, the light module can include an animation control unit, activated by a direction indicator control element, which regulates the sequence of an animation and controls the individual light sources accordingly.

[0017] Furthermore, the microcontroller can be configured to monitor the current consumption of the light module and, if this exceeds a value that is the sum of the continuous operating threshold and the current drawn by the power sink, to switch off the power sink. This prevents unnecessary energy consumption and reduces the use of the power sink to situations where the current consumption threshold is not exceeded, even when an animation is running correctly.

[0018] It could be intended that the microcontroller is configured to record the number of switching-on and / or switching-off maneuvers of the light sources (see also Fig. 4 and 5) and thereby the end of an animation is inferred, and / or the animation control device is configured to activate the current sink at the end of the animation and to signal the end of the animation to the microcontroller based on the resulting current jump, wherein the light module and the upstream lamp control unit are designed in such a way that the power supply to the animation control device is maintained until the end of the animation is detected.

[0019] In this way, terminal control can be implemented. For this purpose, the animation control unit can be designed as a standalone module encompassing the light sources, which in turn is assigned to the lamp module. Alternatively, the animation control unit can also be integrated into the microcontroller or controlled by it.

[0020] Preferably, the lamp control unit is further configured to detect the presence of a current jump in the current of the supplied light module. The lamp control unit is further configured to detect the start of an animation and to count the number of current jumps starting from the beginning of the animation. A reference value is supplied to the lamp control unit, representing the number of current jumps contained in a fully executed animation. The lamp control unit is further configured to deduce the end of the animation by comparing the detected number of current jumps with the reference value, and preferably to then at least temporarily switch off the power supply to the light module. This temporary shutdown can, for example, last until a start signal is received, which can then initiate a new animation.Some animations typically only run once per vehicle start-up – for example, a "Welcome" animation that greets the driver. Other animations can run more frequently – for example, the animation of a flashing turn signal.

[0021] Alternatively, the lamp control unit can also be configured to detect the magnitude of current surges in the supplied light module. The lamp control unit is supplied with at least one reference value corresponding to the animation, indicating the magnitude of the expected current surges. Furthermore, the lamp control unit is configured to compare the magnitude of each current surge with the reference value and, if it deviates from the reference value, to infer the end of the animation and subsequently to at least temporarily switch off the power supply to the light module. Here too, the animation can restart upon receipt of a new start signal. It can be particularly advantageous if the current sink is selected such that the current surge when the current sink is activated is twice the magnitude of the current surge when a light source is activated.This ensures that when a light source is switched on and the current sink to the lamp control unit is simultaneously switched off, a negative current step equal to the usual light source current is simulated. This allows the current change to occur within the range of normal current steps, enabling the current sink to be deactivated during the animation to save power without causing the current step to deviate from the usual magnitude. This prevents an erroneous conclusion about the end of the animation.

[0022] Furthermore, the lamp control unit can be configured to detect the duration of an animation and maintain the power supply to the light module until a target supply duration has elapsed. This target supply duration is defined by the lower of the following two time values: {maximum permissible animation duration, duration until animation end}. If the maximum animation duration is exceeded and the animation does not end, a faulty animation is inferred, and the power supply is shut off. This ensures that, if the animation runs correctly, the power supply is maintained until the end of the animation. This is, for example,This is particularly important when used with a turn signal indicator, which must emit a certain legally prescribed amount of light for at least a specific duration. This amount of light may be reached, for example, at the end of an animation. Therefore, reliably reaching the end of the animation can be of both technical and legal importance.

[0023] In the case of faulty animation - e.g., the absence of current surges due to a failure of a light source - the expiration of the maximum time period allows conclusions to be drawn about the presence of a fault and the power supply to be stopped.

[0024] In particular, it may be provided that the light sources are semiconductor light sources, especially LED light sources.

[0025] Furthermore, the invention relates to a vehicle headlight, in particular a motor vehicle headlight, comprising a lighting or signaling device according to the invention.

[0026] The invention is explained in more detail below with reference to exemplary and non-limiting embodiments, which are illustrated in the figures. These show Figure 1 a schematic representation of a circuit system, Figure 2 a schematic representation of the operating behavior of a conventional light module, Figure 3 a schematic representation of the current consumption of light sources in a modern lighting module when at least one light source fails, Figure 4 the temporal profile of the current consumption of light sources in a modern lighting module during the implementation of a chasing light effect, Figure 5 an exemplary demonstration of how to capture an animation, and Figure 6An example of an alternative way to capture an animation.

[0027] In the following figures, unless otherwise stated, the same reference symbols denote the same features.

[0028] Figure 1 shows a schematic representation of a circuit system 1.

[0029] The circuit system 1 comprises a light module 2 for emitting a light distribution and a lamp control unit 3 for supplying electrical power and monitoring the functionality of the light module 2. The lamp control unit 3 can be a commercially available lamp control unit in which, for monitoring the functionality of the light module 2, the current I is drawn by the light module 2 during operation is measured and compared with a lamp control unit threshold I fail,max (see Fig. 2The lamp control unit 3 is configured to infer the presence of a fault and trigger a fault routine F when the lamp control unit threshold value I fail,max is undershot.

[0030] In Figure 1 Furthermore, a light module 2' is shown with dashed lines, representing a conventional light module comprising an incandescent lamp. Due to the binary operating behavior of incandescent lamps (high current consumption during normal operation, loss of current consumption when the lamp fails), such a light module 2' can be easily detected by the lamp control unit 3 by comparison with a suitably chosen threshold value. This light module 2' is shown only as an example and is not part of the invention or the circuit system 1 according to the invention.

[0031] The light module 2 of the circuit system 1 is – as will be discussed below – designed to behave analogously to a conventional light module 2' with regard to its current consumption, even when using multiple light sources, and thus to be controlled and monitored by the lamp control unit 3. The light module 2 has a number of individually electrically powered light sources 2a, a microcontroller 6 for detecting the operating status of the individual light sources 2a, and at least one controllable device 4 for manipulating the current consumption of the light module 2.

[0032] The microcontroller 6 receives at least one predefined comparison signal, e.g., in the form of a threshold value I IO,min, or a representation signal SA, the comparison signal of which will be discussed in more detail below. The microcontroller 6 is configured to output a control signal Ss by comparing the detected operating state of the individual light sources 2a with the comparison signal I IO,min and / or SA. The control signal Ss is supplied to the controllable device 4 for its control, and the controllable device 4 manipulates the current consumption of the light module 2 accordingly.

[0033] The controllable device 4 is configured to switch off the power supply to the electric light sources 2a if the detected operating state deviates from a target state derived from the comparison information (for example, a continuous operating threshold I IO,min or the signal SA), so that the current drawn I falls below the lamp control unit threshold I fail,max and the lamp control unit 3 infers the presence of a fault. In the figures, the range of values ​​above I IO,min is designated by reference numeral 7a, the range between I IO,min and I fail,max by reference numeral 7b, and the range below I fail,max by reference numeral 7c.

[0034] The device 4 is configured to connect a current sink 4a in the form of a parallel resistor. The device 4 can also be configured to activate a switch connected in series with the light sources in order to force the switching off of all light sources.

[0035] In addition to or as an alternative to the comparison with the continuous operating threshold IIO,min, the comparison information can include a representation of an animation signal SA. The animation relates to a temporal sequence of switching on and / or off the individual light sources 2a, for example, to generate a chasing light effect of a direction indicator. From this, the temporal sequence of the current consumption of the light sources 2a of the light module 2 can be derived. For the duration in which the current consumption is below the continuous operating threshold IIO,min, the auxiliary device 4 can switch on the current sink 4a, so that the total current consumption of the light module 2 does not fall below the continuous operating threshold IIO,min, even when individual light sources 2a are deactivated due to the animation.

[0036] Furthermore, it may be provided that the light module 2 includes an animation control device 5 that can be activated by operating a direction indicator control element, which controls the sequence of an animation and controls the individual light sources 2a for this purpose.

[0037] The invention is now being considered in light of the Figures 2 to 5 discussed again in detail. Figure 2 shows a schematic representation of the operating behavior of a conventional light module that exhibits the aforementioned binary functional behavior. Figure 3In contrast, the operating behavior of a modern lighting module comprehensively demonstrates multiple light sources in different scenarios. Variant A shows a scenario in which a single light source fails and the current draw decreases, but remains above the continuous operating threshold IIO,min. In this case, neither the lamp control unit nor a comparison with the continuous operating threshold IIO,min would detect a fault, as the current remains above the respective limits IIO,min and Ifail,max. However, this fault can be detected by individually monitoring the operating state of the light sources 2a using the microcontroller 6. A similar situation exists in scenario B, where the failure of a light source 2a leads to a current draw that results in an operating current Iist below the value of IIO,min. This fault is also detected by the microcontroller 6.Scenario C subsequently shows the intervention of the microcontroller 6, which makes the fault detectable by the lamp control unit 3. To this end, the controller 6 switches off the remaining light sources 2a, thereby forcing the current Iist to fall below the limit Ifail,max. This drop in current is detected by the lamp control unit 3, and a standard fault routine F can then be triggered.

[0038] Figure 4Figure 1 shows a scenario where a chasing light effect is achieved by successively switching on the light sources 2a. The current Iist increases in stages according to the sequence of switching operations, with the current Iist initially being below the threshold value Ifail,max. This would normally cause the lamp control unit 3 to detect an error, even though the light module 2 is functioning correctly. This can be avoided by connecting a current sink using device 4. This additional current I4 is drawn by the light module 2, ensuring that the current remains above the limit IIO,min even when individual light sources 2a are switched off due to the animation. If the total current draw of the light module 2 exceeds twice the value of I4, the current sink can be deactivated.

[0039] Figure 5This shows an example of how an animation is captured. For example, the lamp control unit 3 detects the current changes, allowing conclusions to be drawn about the progress of the animation. This detection can be combined with the signal SA representing the animation or a derived signal from it. Figure 1 The reference value R1 shown is compared and evaluated. The crosses X mark the time periods in which the current sink X is switched on. In other words, it shows Figure 5A variant of the invention in which the lamp control unit 3 is further configured to detect the presence of a current step Is of the current Iist of the supplied light module 2, wherein the lamp control unit 3 is further configured to detect the start of an animation and to count the number of current steps Is starting from the beginning of the animation, wherein a reference value R1 is supplied to the lamp control unit 3, which represents the number of current steps Is contained in a fully executed animation, wherein the lamp control unit 3 is further configured to deduce the end of the animation based on a comparison of the detected number of current steps Is with the reference value R1, and preferably subsequently to at least temporarily switch off the power supply to the light module 2. The number of LED light sources switched on at the respective time is indicated in the line below the line containing the "X" symbols.The same notation applies to . Fig. 6 .

[0040] Figure 6Figure 1 shows an exemplary representation of an alternative method for capturing an animation. In this representation, the lamp control unit 3 is further configured to detect the magnitude of current jumps Is of the supplied light module 2. The lamp control unit 3 is supplied with at least one reference value R2 corresponding to the animation, indicating the magnitude of the expected current jumps Is. The lamp control unit 3 is further configured to compare the magnitude of each current jump Is with the reference value R2 and, if there is a deviation from the reference value R2, to infer the end of the animation and subsequently to at least temporarily discontinue the power supply to the light module 2.The current sink 4a can be chosen such that the current step I 4 when the current sink 4a is switched on has twice the height of a current step I s when a light source 2a is switched on, so that when a light source 2a is switched on and the current sink 4a is simultaneously switched off towards the lamp control unit 3, a negative current step I s equal to the usual light source current is simulated.

[0041] In general, it can be provided that the lamp control unit 3 is further configured to detect the duration of an animation and to maintain the power supply to the light module 2 until a target supply duration has elapsed, wherein the target supply duration is determined by the lower time value selected from the following two time values: {permissible maximum duration of an animation; duration until end of animation}, wherein, in the event of an exceedance of a maximum duration of an animation and simultaneous failure to reach the end of the animation, a faulty execution of the animation is inferred and the power supply is switched off.

[0042] Both in Figure 5 as well as in Figure 6 The end of the effect can be signaled by a higher jump in the current value, which can be implemented, for example, by switching on the current I 4 of the current sink 4a.

[0043] Any reference numerals in the claims are exemplary and serve only to make the claims easier to read, without limiting them.

Claims

1. Vehicle headlamp, in particular motor vehicle headlamp, comprising an illumination or signaling device, the illumination or signaling device comprising a circuit system (1), the circuit system (1) comprising - a light module (2), in particular a vehicle light module, for emitting a light distribution, - a lamp control unit (3) for the electrical supply and for monitoring the functionality of the light module (2), wherein the lamp control unit (3), for monitoring the functionality of the light module (2), detects a current (Iist) drawn by the light module (2) in the operating state and compares it with a lamp control unit threshold value (Ifail,max), the lamp control unit (3) being set up to infer the presence of a fault and to trigger a fault routine (F) if the current falls below the lamp control unit threshold value (Ifail,max), characterized in that the light module (2) comprises - a number of individually electrically suppliable light sources (2a), - a microcontroller (6) for detecting the operating state of each individual light source (2a), and - at least one controllable auxiliary means (4) for manipulating the current consumption of the light module (2), the auxiliary means (4) comprising a current sink (4a), the current sink (4a) being designed as an electrical load in the form of an ohmic resistor, in particular an ohmic resistor connected in parallel with the light sources (2a), wherein the microcontroller (6) is supplied with at least one predeterminable comparison information item (IIO,min, SA) and the microcontroller (6) is set up to output a control signal (Ss) by comparing the detected operating state of the individual light sources (2a) with the comparison information item (IIO,min, SA), wherein the control signal (Ss) is supplied to the controllable auxiliary means (4) for controlling it and the controllable auxiliary means (4) manipulates the current consumption of the light module (2) as a function thereof, wherein the auxiliary means (4) is configured to switch on the current sink (4a).

2. Vehicle headlamp according to claim 1, wherein the error routine (F) comprises switching off the light module (2) and / or outputting an error signal.

3. Vehicle headlamp according to claim 1 or 2, wherein the controllable auxiliary means (4) is configured to switch off the supply to the electrical light sources (2a) if the detected operating state deviates from a target state derived on the basis of the comparison information (IIO,min, SA), so that the current Iist drawn falls below the lamp control unit threshold value (Ifail,max) and the lamp control unit (3) concludes that a fault is present.

4. Vehicle headlamp according to any of the preceding claims, wherein the auxiliary means (4) is arranged to switch off the individual light sources (2a) in their entirety.

5. Vehicle headlamp according to any of the preceding claims, wherein the comparison information comprises a continuous operation threshold value (IIO,min) which is above the lamp control unit threshold value (Ifail,max).

6. Vehicle headlamp according to claim 5, wherein the comparison information (IIO,min, SA) comprises a representation of an animation signal (SA) relating to an animation in the form of a time sequence of switching on and / or switching off the individual light sources (2a), in particular for generating a running light effect, wherein a time sequence of the current consumption of the light sources (2a) of the light module (2) can be derived therefrom and the controllable auxiliary means (4) is controlled by the microcontroller (6) in such a way that during a sequence of the animation the continuous operation threshold value (IIO,min) is not undershot by selectively switching on the current sink (4a) even when individual light sources (2a) are deactivated as a result of the animation.

7. Vehicle headlamp according to claim 6, wherein the microcontroller (6) detects a current current consumption (Iist) of the light module (2) and, if a value is exceeded which consists of the sum of the continuous operation threshold value (IIO,min) and the current (I4) consumed by the current sink, causes the current sink (4a) to be switched off.

8. Vehicle headlamp according to claim 6 or 7, wherein the light module (2) comprises an animation control device (5) activatable by actuating a direction indicator control element which regulates the sequence of an animation and controls the individual light sources (2a) for this purpose.

9. Vehicle headlamp according to any of claims 6 to 8, wherein the lamp control unit (3) is furthermore configured to detect the presence of a current jump (Is) of the current (Iist) of a supplied light module (2), wherein the lamp control unit (3) is furthermore configured to detect the start of an animation and to count the number of current jumps (Is) starting from the start of the animation, wherein a reference value (R1) is supplied to the lamp control unit (3), which reflects the number of current jumps (Is) contained in a completely elapsed animation, wherein the lamp control unit (3) is furthermore configured to infer the end of the animation on the basis of a comparison of the detected number of current jumps (Is) with the reference value (R1), and preferably subsequently to at least temporarily adjust a power supply to the light module (2).

10. Vehicle headlamp according to claim 9, wherein the lamp control unit (3) is furthermore configured to detect the duration of an animation and to maintain a power supply to the light module (2) until the expiry of a target supply duration, wherein the target supply duration is defined by a low time value selected from the following two time values: {permissible maximum time duration of an animation, time duration until end of animation} , whereby in the event that a maximum time duration of an animation is exceeded and the end of the animation is not reached at the same time, a faulty sequence of the animation is inferred and the power supply is stopped.

11. Vehicle headlamp according to any of the preceding claims, wherein the light sources (2a) are semiconductor light sources, in particular LED light sources (2a).

12. Vehicle, in particular motor vehicle, comprising a vehicle headlamp according to any of the preceding claims.