LED lamp, diagnostic system and method for monitoring an LED lamp

Abstract

LED light (14) for a motor vehicle, comprising a control circuit (22) having an input terminal (26) for connection to a light control module (12) and an LED driver (24) connected to an LED module (28), wherein the control circuit (22) has a regulator (32) configured to keep the current consumption of the LED light (14) constant, characterized in that the LED driver (24) is connected to a current sink (30) and is configured to switch off the current sink (30) in the event of a fault.

Description

Background of the invention

[0001] The invention relates to an LED light for a motor vehicle with a control circuit having an input terminal for connection to a light control module and an LED driver connected to an LED module.

[0002] Furthermore, the invention relates to a diagnostic system for an LED lamp and a method for monitoring an LED lamp of a motor vehicle.

[0003] DE 10 2009 052 690 B3 discloses a method for operating LED lights in motor vehicles, wherein the LED lights are used as a replacement for conventional incandescent lamps, wherein in order to avoid an error message due to the lower power consumption of the LED lights, an additional load is simulated and the necessary additional power, which runs via the simulated additional load, is fed back into the vehicle electrical system.

[0004] FR 2 939 213 A1 relates to a device according to the preamble of claim 1.

[0005] FR 3 035 236 A1 relates to a device and a method which make it possible to dynamically adjust the charging current in an electronic circuit relative to a predetermined threshold value.

[0006] DE 10 2008 048 197 A1 discloses a control unit for a lighting device for a motor vehicle, which has a light source arrangement with at least one light-emitting diode, wherein the control unit comprises a current sensor for detecting an input current from an on-board electrical system of the motor vehicle and a control circuit for controlling and / or regulating the motor vehicle lighting device.

[0007] DE 198 52 351 A1 discloses a diagnostic system for an LED light in a motor vehicle. A lighting control module controls the LED light via a supply line. In the event of a fault, the LED light transmits a diagnostic signal to the lighting control module via the supply line. To this end, in the event of a fault, the LED light modulates the current consumed using a switchable current sink, whereby the lighting control module receives coded diagnostic information via the supply line.

[0008] Monitoring the functionality of LED luminaires is both desirable for customers and often required by law. LED control electronics can often only communicate their faults to a lighting control module via the current consumption. For this purpose, the lighting control module evaluates the output current via an internal current measurement. Typically, two fault thresholds describe the "no fault" or "fault" state. There is an upper output current threshold that describes the "no fault" state, and there is a lower fault threshold that describes the "fault" state.

[0009] The upper current threshold must be designed to take all independent parameters into account. Due to the large number of independent parameters, the variance is relatively large. In particular, the threshold is currently determined by the following independent parameters: input voltage, component tolerance, temperature, efficiency, and LED forward voltage. Object of the invention

[0010] It is an object of the invention to propose an LED lamp in which an upper diagnostic current threshold can be set independently of parameters of the LED lamp. Description of the invention

[0011] This object is achieved according to the invention by an LED light for a motor vehicle having the features of patent claim 1.

[0012] If there is no fault in the LED luminaire, particularly the LED module, a lighting control module connected to the input terminal always sees the same output current corresponding to the current consumption of the LED luminaire, regardless of input voltage, temperature, efficiency, LED forward voltage, etc. This allows component tolerances, input voltage, and temperature to be compensated for. This creates a "hard" threshold that always remains the same, even after years of operation and / or production fluctuations. This reduces the tolerance window and simplifies and increases the reliability of evaluation. Even if the efficiency improves over the years due to component adjustments, the upper current threshold can remain constant by controlling it to a predefined, fixed current consumption value.

[0013] The controller can be temperature compensated and operate with a small control deviation.

[0014] It is particularly preferred if the control circuit has a current sink connected in parallel to the LED driver and connected to the controller. The controller can then regulate the current consumption by controlling the current sink. Thus, if the LED driver draws more current, the current sink can be controlled to consume less current, so that the sum of the current into the LED driver and the current into the current sink remains constant. The lighting control module therefore always sees the same output current, which corresponds to the current consumption of the LED light.

[0015] The LED driver is connected to the current sink and configured to shut down the current sink in the event of a fault. If the LED driver detects a fault, particularly a fault in the LED module, it can trigger the current sink and shut it down. The controller is then no longer able to maintain a constant current consumption corresponding to an upper current threshold. The current consumption of the LED luminaire collapses. This causes the output current of the lighting control module to also collapse, causing the current to fall below a second current threshold, allowing the lighting control module to clearly detect a fault.

[0016] According to a preferred embodiment, a current sensor can be provided that is configured to detect the current flowing through the input terminal. The current sensor can be integrated into the controller. In particular, the current sensor can be designed as a shunt.

[0017] The LED module can have at least one LED. The LED module is preferably designed as an LED matrix. The LED module can have LEDs connected in series and / or in parallel.

[0018] Also within the scope of the invention is a diagnostic system comprising an LED light according to the invention and a light control module configured to connect the LED light to an operating voltage source and monitor the current consumption of the LED light. During normal operation, i.e., when no fault is present, the current consumption of the LED light remains constant due to the inventive design of the LED light. However, if this current consumption drops, this indicates a fault in the LED light. This can be detected by the diagnostic system monitoring the current consumption of the LED light.

[0019] The invention also includes a method for monitoring an LED light of a motor vehicle, in which the current consumption of the LED light is regulated to a predetermined constant value by controlling a current sink via a controller to compensate for current consumption fluctuations of the LED driver. The current sink can be connected in parallel to the LED driver of the LED light. The current sink can comprise a series circuit of a transistor and a resistor.

[0020] A current sensor can monitor the input current and thus the current consumption of the control electronics. The current consumption is the sum of the current of the current sink and the current of the LED driver. The controller regulates to a fixed value by controlling the current sink accordingly. If the LED driver requires less current, more current flows through the current sink. If the LED driver requires more current, less current flows through the current sink.

[0021] In the event of a fault, the LED driver can switch off the current sink. Only the LED driver's fault current flows, which is significantly lower than the current consumption in a fault-free situation. This current is below a lower current threshold, allowing it to be detected that a fault exists in the LED luminaire.

[0022] Alternatively or additionally, it can be provided that in the event of a fault, a lighting control module can switch off the LED light and thus also the current sink.

[0023] Further advantages of the invention will become apparent from the description and the drawings. Likewise, the above-mentioned and further-described features can be used individually or in combination in any desired manner. The embodiments shown and described are not intended to be exhaustive, but rather are exemplary in nature for describing the invention. Detailed description of the invention and drawing Fig. 1 shows a schematic representation of a diagnostic system; Fig. Figure 2 shows a diagram to illustrate the different current thresholds.

[0024] The Fig. 1 shows a diagnostic system 10 with a light control module 12 and an LED light 14. The light control module 12 is connected to a supply voltage 16, in particular a vehicle battery. A switch 18 connects the LED light 14 to the supply voltage 16. The light control module 12 also has a diagnostic device 20 with which the output current, i.e., the current consumed by the LED light 14, can be detected.

[0025] The LED light 14 includes control electronics 22, which has an LED driver 24 connected to an input terminal 26. The LED driver 24 is in turn connected to an LED module 28. The current drawn at the input terminal 26 corresponds to the output current of the light control module 12. The drawn current is divided into a current drawn by the LED driver 24 and a current drawn by a current sink 30. The current sink 30 and the LED driver 24 are connected in parallel.

[0026] A controller 32 is connected to or includes a current sensor 34. The current sensor 34 detects the current drawn by the LED light 14. The controller 32 is configured to regulate the drawn current to a predetermined value. For this purpose, the controller 32 controls the current sink 30. If more current is required by the LED driver 24, the current sink 30 is controlled to draw less current, so that the total current drawn at the input terminal 26 remains as constant as possible.

[0027] If the LED driver 24 detects a fault, particularly a fault in the LED module 28, the LED driver 24 switches off the current sink 30. This leads to a drop in the current drawn at the input terminal 26. This current drop can be detected by the diagnostic device 20 of the lighting control module 12.

[0028] In the Fig.Figure 2 schematically shows that the current drawn at input terminal 26 can vary between 0 amperes and Imax, i.e., the maximum output current of the lighting control module 12. If the output current is above a threshold S2, this means that there is no fault in the LED module 14. If, however, the current drops to a value below the threshold S1, a fault exists in the LED module 14.

[0029] The diagnostic device 20 monitors whether the current consumed by the LED module 14 is above the threshold S2 or below the threshold S1.

[0030] Because the controller 32 is configured to regulate the consumed current to a value at or above the threshold S2 during normal operation, i.e. when there is no fault, and no variable parameters are included in the control, the diagnosis as to whether there is a fault in the LED module 14 is independent of variable parameters and is therefore particularly reliable.

Claims

[1] LED light (14) for a motor vehicle with a control circuit (22) having an input terminal (26) for connection to a light control module (12) and an LED driver (24) connected to an LED module (28), wherein the control circuit (22) has a controller (32) which is designed to keep the current consumption of the LED light (14) constant, characterized by that the LED driver (24) is connected to a current sink (30) and is configured to switch off the current sink (30) in the event of a fault. [2] LED lamp according to claim 1, characterized by that the control circuit (22) has a current sink (30) connected in parallel to the LED driver (24) and connected to the controller (32). [3] LED lamp according to one of the preceding claims, characterized by that a current sensor (34) is provided which is designed to detect the current flowing via the input terminal (26). [4] LED lamp according to one of the preceding claims, characterized by that the current sensor (34) is integrated into the controller (32). [5] Diagnostic system with an LED light (14) according to one of the preceding claims and a light control module (12) which is configured to connect the LED light (14) to an operating voltage source (16) and to monitor the current consumption of the LED light (14). [6] Method for monitoring an LED lamp (14) of a motor vehicle, in which the current consumption of the LED lamp (14) is regulated to a predetermined constant value by controlling a current sink (30) by a controller (32) in order to compensate for current consumption fluctuations of an LED driver (24), characterized by that in the event of a fault the current sink (30) is switched off by the LED driver (24).

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