WO2008006518A1 - Circuit arrangement for electrically triggering a motor vehicle headlight - Google Patents

Circuit arrangement for electrically triggering a motor vehicle headlight Download PDF

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Publication number
WO2008006518A1
WO2008006518A1 PCT/EP2007/006001 EP2007006001W WO2008006518A1 WO 2008006518 A1 WO2008006518 A1 WO 2008006518A1 EP 2007006001 W EP2007006001 W EP 2007006001W WO 2008006518 A1 WO2008006518 A1 WO 2008006518A1
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Prior art keywords
circuit
light
circuit arrangement
bypass
arrangement according
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PCT/EP2007/006001
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German (de)
French (fr)
Inventor
Nikolaus Decius
Original Assignee
Hella Kgaa Hueck & Co.
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Application filed by Hella Kgaa Hueck & Co. filed Critical Hella Kgaa Hueck & Co.
Priority to EP07785915A priority Critical patent/EP2039224A1/en
Publication of WO2008006518A1 publication Critical patent/WO2008006518A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices

Definitions

  • the invention relates to a circuit arrangement for the electrical control of a motor vehicle headlamp whose light source consists of two or more light-emitting diodes (LEDs). Such a headlight is also referred to as LED headlights.
  • LEDs light-emitting diodes
  • a motor vehicle headlamp whose light source consists of an LED matrix with a multiplicity of LEDs is known, for example, from DE 100 09 782 A1.
  • the characteristic (light distribution, range) of the emerging from the headlight beam can be changed and thus respond to different circumstances (city, highway, cornering, selective illumination of critical areas, etc.).
  • the spatial arrangement of the LEDs in a matrix says nothing about the electrical interconnection of the LEDs with each other.
  • the LEDs of the LED matrix would have to be controlled / supplied individually via a controllable constant current source or a controllable constant current sink (so-called high / low side current drivers).
  • a controllable constant current source or a controllable constant current sink in each of the power sources creates a thermal power loss.
  • N current drivers are required. derlich, which in total produce a relatively high thermal power loss. Since for the realization of the light values of a motor vehicle headlight quite 30 to 50 high-power LEDs are required, which can be operated with a current of up to 1 amp or more, also result in correspondingly high thermal power losses per headlight.
  • the supply unit is arranged with the strong heat-generating current drivers of the unit comprising the LEDs separately, for example in a central light control unit, the space of the arranged in the headlight unit for the LEDs, is separated.
  • the LED module may be a carrier as a receiving platform for the LEDs, for example a printed circuit board. This in turn means that between the supply unit and the LED assembly N relatively high-current carrying power lines and a common return - ie a total of N + 1 lines - are required. This disadvantageously associated with correspondingly high material and cable laying costs.
  • the object of the invention is therefore to provide a more cost-effective and lower-loss circuit arrangement for LED headlights, which nevertheless allows to operate different subsets of LEDs differently.
  • the circuit arrangement has at least one series connection with two or more light-emitting diodes which is connected to a constant-current source.
  • at least one light-emitting diode is connected in parallel with a controllable bypass circuit for controlling the light intensity of this light-emitting diode.
  • the control of the bypass circuit is done via a control unit. Due to the series connection of the LEDs, only one supply line with high current carrying capacity between the constant current source and the series connection as well as a return line (ground line) is necessary for the power supply. By reducing the high current carrying lines between the central light controller, in which the constant current source is located, and the LED assembly in the headlight, there is a significant cost savings.
  • the flexible control of different LED subsets is effected by the bypass circuits, which are preferably connected in parallel to each LED of the series circuit. By passing some or all of the current flowing through the series circuit around the LED, the light intensity of the respective LED can be adjusted individually. For the control of the bypass circuits no high current carrying lines are required. The power loss in the bypass circuits is negligible. In this way, each individual LED in the matrix or even groups of LEDs, which may or may not be spatially adjacent, are quasi addressed and independently controlled with regard to the light intensity.
  • the LED series connection In order to avoid high, safety-critical supply voltages for the LED series connection with a given number of N LEDs in the LED headlight, it is intended to distribute the N LEDs on two or more series circuits, so that in each series circuit, for example, N / 2 LEDs are arranged.
  • the height of the supply voltage for an LED series circuit determined by the sum of the forward voltages of the LEDs.
  • the forward voltage of a single high power LED is about 4 volts.
  • Supply voltages of greater than 60 volts should be avoided. Even if in the circuit arrangement according to the invention tion two or more series circuits are provided, the number of expensive high-current carrying lines is still significantly lower than in a separate parallel connection of all LEDs.
  • each series circuit preferably comprises the same number of LEDs. However, series circuits with a different number of LEDs are also provided.
  • Each LED is connected in parallel with an actively controllable bypass circuit for controlling the light intensity of this LED.
  • the activation of the bypass circuit takes place in each case with little loss and quickly via a semiconductor switch (HS), preferably a field-effect transistor.
  • the semiconductor switches themselves are in turn driven by a control unit.
  • the control unit may be a microprocessor or a programmable logic unit.
  • the bypass is digitally turned on or off by means of the semiconductor switches, i. the semiconductor switch causes in a first switching position a complete diversion of the current to the associated light emitting diode via the bypass and in the other second switching position blocking the bypass. In the first switching position, the LED is thus operated with the maximum possible light intensity, while it is switched off in the second switching position and thus dark.
  • the semiconductor switch is driven in this embodiment via a pulse width modulated control signal (PWM control signal).
  • PWM control signal pulse width modulated control signal
  • the light intensity of the associated light-emitting diode can be adjusted continuously via the ratio of the Pulseinschaltdauer to Pulsausschaltdauer.
  • the fundamental frequency of the PWM control signal is chosen so high that the individual switching on and off pulses can no longer be resolved by the eye, but only a dimming is perceived.
  • only a partial diversion of the current around the associated LED is effected via the semiconductor switch.
  • the series circuits with the LEDs and the associated bypass circuits are integrated with the control unit in a structural unit which is arranged in or on the headlight.
  • N LEDs To power N LEDs, only two high current carrying power lines are required for the two LED series and one ground line.
  • To control the control unit between the central light control unit and the control unit of the LED assembly only a few non-high current carrying control signal lines (Datain, DataOut, Clock, strobe) including a TTL supply line (5 volts, 10 mA) is necessary. Overall, only 8 lines between the central light control unit and the LED unit in the headlight are required in the illustrated example for the supply and control of N LEDs.
  • the bypass circuits with the semiconductor switches are arranged together with the LEDs on a support, for example a printed circuit board.
  • This carrier then corresponds to the LED assembly in the headlight or at least a part thereof. Since the semiconductor switches, which are preferably activated in PWM mode, are arranged spatially very close to the LEDs in this integrated embodiment and the bypass lines are correspondingly short, the electrical overall electromagnetic radiation of the entire circuit arrangement is low. With regard to the integration, it is particularly advantageous if the control unit is also arranged on the carrier.
  • the central light control unit is determined based on specific input variables (eg light switch position, turn signal, or sensor signals from various sensors such as steering angle sensor or yaw rate sensor, vehicle speed sensor, light sensor or camera, etc.) based on previously defined algorithms, which LED or which groups / subsets of LEDs with which light intensity (or relative light intensity) should be switched on in order to achieve the optimum light distribution and range for a specific situation.
  • This information is then transmitted via the control signal lines to the control unit of the LED assembly, which then applied to the LEDs associated semiconductor switch (HS) with a desired light intensity corresponding PWM signal.

Abstract

Disclosed is a circuit arrangement for electrically triggering a motor vehicle headlight, the light source of which comprises two or more light emitting diodes (LEDs). Said circuit arrangement is characterized in that at least one series circuit is provided which encompasses two or more light emitting diodes and is connected to a constant-current source, a controllable bypass circuit is connected in parallel to at least one light emitting diode in order to control the light intensity of said light emitting diode, and a control unit is provided for triggering the bypass circuit.

Description

Titel: Schaltungsanordnung zur elektrischen Ansteuerung eines Kraftfahrzeug- Scheinwerfers Title: Circuit arrangement for the electrical control of a motor vehicle headlight
Die Erfindung betrifft eine Schaltungsanordnung zur elektrischen Ansteuerung eines Kraftfahrzeug-Scheinwerfers, dessen Lichtquelle aus zwei oder mehr Leuchtdioden (LEDs) besteht. Ein derartiger Scheinwerfer wird auch als LED-Scheinwerfer bezeichnet.The invention relates to a circuit arrangement for the electrical control of a motor vehicle headlamp whose light source consists of two or more light-emitting diodes (LEDs). Such a headlight is also referred to as LED headlights.
Ein Kraftfahrzeug-Scheinwerfer, dessen Lichtquelle aus einer LED-Matrix mit einer Vielzahl von LEDs besteht ist beispielsweise aus der DE 100 09 782 A1 bekannt. Durch den Betrieb von unterschiedlichen Teilmengen der LEDs kann dabei die Charakteristik (Lichtverteilung, Reichweite) des aus dem Scheinwerfer austretenden Lichtbündels verändert werden und so auf unterschiedliche Gegebenheiten (Stadt-, Autobahnfahrt, Kurvenfahrt, selektive Ausleuchtung kritischer Bereiche etc.) reagiert werden. Die räumliche Anordnung der LEDs in einer Matrix (Zeilen/Spalten) sagt nichts über die elektrische Verschaltung der LEDs untereinander aus.A motor vehicle headlamp whose light source consists of an LED matrix with a multiplicity of LEDs is known, for example, from DE 100 09 782 A1. Through the operation of different subsets of the LEDs, the characteristic (light distribution, range) of the emerging from the headlight beam can be changed and thus respond to different circumstances (city, highway, cornering, selective illumination of critical areas, etc.). The spatial arrangement of the LEDs in a matrix (rows / columns) says nothing about the electrical interconnection of the LEDs with each other.
Aus der DE 102 42 864 A1 ist eine Reihenschaltung von Leuchtdioden in einem Kraftfahrzeug-Scheinwerfer bekannt, wobei die Reihenschaltung über ein zentrales, vom Scheinwerfer getrenntes Steuergerät versorgt wird. Zwar können die LEDs in dieser Reihenschaltung baulich auch in Form einer Matrix angeordnet sein, ein wahlweise unterschiedlicher Betrieb von unterschiedlichen Teilmengen von LEDs ist aufgrund der Reihenschaltung jedoch nicht möglich, da die LEDs innerhalb der Reihenschaltung alle gleich angesteuert/betrieben werden.From DE 102 42 864 A1 a series connection of light emitting diodes in a motor vehicle headlight is known, wherein the series circuit is supplied via a central, separate from the headlight control unit. Although the LEDs in this series connection can also be structurally arranged in the form of a matrix, an optionally different operation of different subsets of LEDs is not possible because of the series connection, since the LEDs within the series circuit are all driven the same way.
Um vollkommen flexibel unterschiedliche Teilmengen von LEDs betreiben zu können, müßten die LEDs der LED-Matrix jeweils einzeln über eine steuerbare Konstantstromquelle oder eine steuerbare Konstantstromsenke (sogenannte High-/Lowside- Stromtreiber ) angesteuert/versorgt werden. In jeder der Stromquellen entsteht dabei eine thermische Verlustleistung. Bei N LEDs in der Matrix sind N Stromtreiber erfor- derlich, die in Summe eine relativ hohe thermische Verlustleistung erzeugen. Da für die Realisierung der Lichtwerte eines Kraftfahrzeug-Scheinwerfers durchaus 30 bis 50 High-Power-LEDs erforderlich sind, die mit einem Strom von bis zu 1 Ampere oder mehr betrieben werden können, ergeben sich auch entsprechend hohe thermische Verlustleistungen pro Scheinwerfer. Da LEDs bei zu hohen Temperaturen zerstört werden oder zumindest degradieren, und daher bereits die Eigenerwärmung der LEDs kritisch ist, ist es erforderlich, dass die Versorgungseinheit mit den stark wärmeentwickelnden Stromtreibern von der die LEDs aufweisenden Baueinheit getrennt angeordnet ist, z.B. in einem zentralen Lichtsteuergerät, das räumlich von der im Scheinwerfer angeordneten Baueinheit für die LEDs, getrennt ist. Bei der LED-Baueinheit kann es sich um einen Träger als Aufnahmeplattform für die LEDs handeln, z.B. eine Leiterplatte. Dies hat nun wiederum zur Folge, dass zwischen der Versorgungseinheit und der LED-Baueinheit N relativ hochstromtragfähige Stromleitungen und eine Sammelrückleitung - also insgesamt N+1 Leitungen - erforderlich sind. Damit sind in nachteiliger Weise entsprechend hohe Material- und Leitungsverlegungskosten verbunden.In order to be able to operate completely flexibly different subsets of LEDs, the LEDs of the LED matrix would have to be controlled / supplied individually via a controllable constant current source or a controllable constant current sink (so-called high / low side current drivers). In each of the power sources creates a thermal power loss. For N LEDs in the matrix, N current drivers are required. derlich, which in total produce a relatively high thermal power loss. Since for the realization of the light values of a motor vehicle headlight quite 30 to 50 high-power LEDs are required, which can be operated with a current of up to 1 amp or more, also result in correspondingly high thermal power losses per headlight. Since LEDs are destroyed at high temperatures or at least degrade, and therefore already the self-heating of the LEDs is critical, it is necessary that the supply unit is arranged with the strong heat-generating current drivers of the unit comprising the LEDs separately, for example in a central light control unit, the space of the arranged in the headlight unit for the LEDs, is separated. The LED module may be a carrier as a receiving platform for the LEDs, for example a printed circuit board. This in turn means that between the supply unit and the LED assembly N relatively high-current carrying power lines and a common return - ie a total of N + 1 lines - are required. This disadvantageously associated with correspondingly high material and cable laying costs.
Aufgabe der Erfindung ist es daher, eine kostengünstigere und verlustärmere Schaltungsanordnung für LED-Scheinwerfer zu schaffen, die es dennoch gestattet, unterschiedlichen Teilmengen der LEDs unterschiedlich zu betreiben.The object of the invention is therefore to provide a more cost-effective and lower-loss circuit arrangement for LED headlights, which nevertheless allows to operate different subsets of LEDs differently.
Diese Aufgabe wird durch die Merkmale des Anspruches 1 gelöst. Die sich daran anschließenden abhängigen Ansprüche beziehen sich auf vorteilhafte Ausgestaltungen der Erfindungen.This object is solved by the features of claim 1. The subsequent dependent claims relate to advantageous embodiments of the inventions.
Erfindungsgemäß weist die Schaltungsanordnung mindestens eine Reihenschaltung mit zwei oder mehr Leuchtdioden auf, die an eine Konstantstromquelle angeschlossen ist. Dabei ist nun mindestens einer Leuchtdiode eine steuerbare Bypass-Schaltung zur Steuerung der Lichtintensität dieser Leuchtdiode parallel geschaltet. Die Ansteuerung der Bypass-Schaltung geschieht über eine Steuereinheit. Durch die Reihenschaltung der LEDs ist zur Stromversorgung nur eine hochstromtrag- fähige Versorgungsleitung zwischen der Konstantstromquelle und der Reihenschaltung sowie eine Rückleitung (Masseleitung) notwendig. Durch die Reduzierung der hochstromtragfähigen Leitungen zwischen dem zentralen Lichtsteuergerät, in dem sich die Konstantstromquelle befindet, und der LED-Baueinheit im Scheinwerfer, ergibt sich eine erhebliche Kosteneinsparung.According to the invention, the circuit arrangement has at least one series connection with two or more light-emitting diodes which is connected to a constant-current source. In this case, at least one light-emitting diode is connected in parallel with a controllable bypass circuit for controlling the light intensity of this light-emitting diode. The control of the bypass circuit is done via a control unit. Due to the series connection of the LEDs, only one supply line with high current carrying capacity between the constant current source and the series connection as well as a return line (ground line) is necessary for the power supply. By reducing the high current carrying lines between the central light controller, in which the constant current source is located, and the LED assembly in the headlight, there is a significant cost savings.
Zwar tritt auch in der Konstantstromquelle der erfindungsgemäßen Schaltungsanordnung noch eine Verlustleistung auf, die allerdings wesentlich geringer ist als die Ge- samt-Verlustleistung einer Parallelschaltung von mehreren LEDs, die jeweils von einer eigenen Stromquelle versorgt werden.Although in the constant current source of the circuit arrangement according to the invention still occurs on a power loss, which, however, is substantially less than the total power loss of a parallel circuit of multiple LEDs, each of which is powered by its own power source.
Die flexible Ansteuerung unterschiedlicher LED-Teilmengen wird durch die Bypass- Schaltungen bewirkt, die vorzugsweise jeder LED der Reihenschaltung parallel geschaltet sind. Indem ein Teil oder der gesamte Strom, der durch die Reihenschaltung fließt, um die LED herum geleitet wird, läßt sich die Lichtintensität der jeweiligen LED individuell einstellen. Für die Ansteuerung der Bypass-Schaltungen werden keine hochstromtragfähigen Leitungen benötigt. Auch die Verlustleistung in den Bypass- Schaltungen ist vernachlässigbar. Auf diese Weise kann jede einzelne LED in der Matrix oder auch Gruppen von LEDs, die räumlich benachbart sein können oder auch nicht, quasi adressiert und hinsichtlich der Lichtintensität unabhängig angesteuert werden.The flexible control of different LED subsets is effected by the bypass circuits, which are preferably connected in parallel to each LED of the series circuit. By passing some or all of the current flowing through the series circuit around the LED, the light intensity of the respective LED can be adjusted individually. For the control of the bypass circuits no high current carrying lines are required. The power loss in the bypass circuits is negligible. In this way, each individual LED in the matrix or even groups of LEDs, which may or may not be spatially adjacent, are quasi addressed and independently controlled with regard to the light intensity.
Um bei einer gegebenen Anzahl von N LEDs im LED-Scheinwerfer, hohe, sicherheitskritische Versorgungsspannungen für die LED-Reihenschaltung zu vermeiden, ist es vorgesehen, die N LEDs auf zwei oder mehr Reihenschaltungen zu verteilen, so dass in jeder Reihenschaltung z.B. N/2 LEDs angeordnet sind. Dabei bestimmt sich die Höhe der Versorgungsspannung für eine LED-Reihenschaltung nach der Summe der Flußspannungen der LEDs. Die Flußspannung einer einzelnen HighPower-LED beträgt beispielsweise ca. 4 Volt. Dabei sollten Versorgungsspannungen von größer als 60 Volt vermieden werden. Auch wenn in der erfindungsgemäßen Schaltungsanord- nung zwei oder mehr Reihenschaltungen vorgesehen sind, so ist die Zahl der teueren hochstromtragfähigen Leitungen immer noch deutlich geringer als bei einer separaten Parallelschaltung sämtlicher LEDs.In order to avoid high, safety-critical supply voltages for the LED series connection with a given number of N LEDs in the LED headlight, it is intended to distribute the N LEDs on two or more series circuits, so that in each series circuit, for example, N / 2 LEDs are arranged. In this case, the height of the supply voltage for an LED series circuit determined by the sum of the forward voltages of the LEDs. For example, the forward voltage of a single high power LED is about 4 volts. Supply voltages of greater than 60 volts should be avoided. Even if in the circuit arrangement according to the invention tion two or more series circuits are provided, the number of expensive high-current carrying lines is still significantly lower than in a separate parallel connection of all LEDs.
Anhand der beigefügten Zeichnung (Figur 1 ), welche eine schematische Darstellung der erfindungsgemäßen Schaltungsanordnung zeigt, soll die Erfindung nachfolgend näher erläutert werden.Reference to the accompanying drawing (Figure 1), which shows a schematic representation of the circuit arrangement according to the invention, the invention will be explained in more detail below.
Dargestellt ist eine Schaltungsanordung für einen LED-Scheinwerfer, bei der die LEDs aus spannungstechnischen Gründen auf zwei Reihenschaltungen aufgeteilt sind, wobei jede Reihenschaltung vorzugsweise die gleiche Anzahl von LEDs umfasst. Allerdings sind auch Reihenschaltungen mit einer unterschiedlichen Anzahl von LEDs vorgesehen. Dabei ist jeder LED eine aktiv steuerbare Bypass-Schaltung zur Steuerung der Lichtintensität dieser LED parallel geschaltet. Die Ansteuerung der Bypass- Schaltung erfolgt jeweils verlustarm und schnell über einen Halbleiterschalter (HS), vorzugsweise ein Feldeffekttransistor. Die Halbleiterschalter selbst werden nun wiederum von einer Steuereinheit angesteuert. Bei der Steuereinheit kann es sich um einen Mikroprozessor oder eine programmierbare Logikeinheit handeln.Shown is a circuit arrangement for an LED headlight, in which the LEDs are divided voltage-related reasons on two series circuits, each series circuit preferably comprises the same number of LEDs. However, series circuits with a different number of LEDs are also provided. Each LED is connected in parallel with an actively controllable bypass circuit for controlling the light intensity of this LED. The activation of the bypass circuit takes place in each case with little loss and quickly via a semiconductor switch (HS), preferably a field-effect transistor. The semiconductor switches themselves are in turn driven by a control unit. The control unit may be a microprocessor or a programmable logic unit.
In einer Ausführungsform wird mittels der Halbleiterschalter der Bypass digital ein bzw. ausgeschaltet, d.h. der Halbleiterschalter bewirkt in einer ersten Schaltposition eine vollständige Umleitung des Stromes um die zugehörige Leuchtdiode über den Bypass und in der anderen zweiten Schaltposition eine Sperrung des Bypasses. In der ersten Schaltposition wird die LED also mit der maximal möglichen Lichtintensität betrieben, während sie in der zweiten Schaltposition ausgeschaltet und damit dunkel ist.In one embodiment, the bypass is digitally turned on or off by means of the semiconductor switches, i. the semiconductor switch causes in a first switching position a complete diversion of the current to the associated light emitting diode via the bypass and in the other second switching position blocking the bypass. In the first switching position, the LED is thus operated with the maximum possible light intensity, while it is switched off in the second switching position and thus dark.
In besonders vorteilhafter Weise wird der Halbleiterschalter in dieser Ausführungsform über ein pulsweitenmoduliertes Steuersignal (PWM-Steuersignal) angesteuert. Auf diese Weise kann die Lichtintensität der zugehörigen Leuchtdiode über das Verhältnis der Pulseinschaltdauer zur Pulsausschaltdauer stufenlos eingestellt werden. Die Grundfrequenz des PWM-Steuersignals wird dabei so hoch gewählt, dass die einzelnen Ein- und Ausschaltpulse vom Auge nicht mehr aufgelöst werden können, sondern nur eine Dimmung wahrgenommen wird.In a particularly advantageous manner, the semiconductor switch is driven in this embodiment via a pulse width modulated control signal (PWM control signal). In this way, the light intensity of the associated light-emitting diode can be adjusted continuously via the ratio of the Pulseinschaltdauer to Pulsausschaltdauer. The The fundamental frequency of the PWM control signal is chosen so high that the individual switching on and off pulses can no longer be resolved by the eye, but only a dimming is perceived.
In einer alternativen Ausführungsform wird über den Halbleiterschalter nur eine teilweise Umleitung des Stromes um die zugehörige LED bewirkt.In an alternative embodiment, only a partial diversion of the current around the associated LED is effected via the semiconductor switch.
Die Reihenschaltungen mit den LEDs und den zugehörigen Bypass-Schaltungen sind mit der Steuereinheit in einer Baueinheit integriert, welche im oder am Scheinwerfer angeordnet ist.The series circuits with the LEDs and the associated bypass circuits are integrated with the control unit in a structural unit which is arranged in or on the headlight.
Die elektrische Versorgung der LED-Reiheinschaltungen und die Ansteuerung der Steuereinheit erfolgt über ein von dieser Baueinheit räumlich entferntes zentrales Lichtsteuergerät, in dem die Konstantstromquelle zur Stromversorgung der Reihenschaltungen sowie eine Lichtsteuereinheit zur Ansteuerung der Steuereinheit in der LED-Baueinheit untergebracht ist. Zur Stromversorgung von N LEDs sind nur 2 hoch- stromtragfähige Versorgungsleitungen für die beiden LED-Reihenschaltungen und eine Masseleitung erforderlich. Zur Ansteuerung der Steuereinheit sind zwischen der zentralen Lichtsteuereinheit und der Steuereinheit der LED-Baueinheit nur wenige nicht hochstromtragfähige Steuersignalleitungen (Datain, DataOut, Clock, Strobe) einschließlich einer TTL-Versorgungsleitung (5 Volt, 10 mA) notwendig. Insgesamt sind in dem dargestellten Beispiel zur Versorgung und Ansteuerung von N LEDs nur 8 Leitungen zwischen dem zentralen Lichtsteuergerät und der LED-Baueinheit im Scheinwerfer erforderlich.The electrical supply of the LED series connections and the control of the control unit via a spatially remote from this unit central light control unit, in which the constant current source for powering the series circuits and a light control unit for controlling the control unit is housed in the LED assembly. To power N LEDs, only two high current carrying power lines are required for the two LED series and one ground line. To control the control unit between the central light control unit and the control unit of the LED assembly only a few non-high current carrying control signal lines (Datain, DataOut, Clock, strobe) including a TTL supply line (5 volts, 10 mA) is necessary. Overall, only 8 lines between the central light control unit and the LED unit in the headlight are required in the illustrated example for the supply and control of N LEDs.
In einer vorteilhaften Ausführungsform sind die Bypass-Schaltungen mit den Halbleiterschaltern gemeinsam mit den LEDs auf einem Träger, z.B. einer Leiterplatte, angeordnet. Dieser Träger entspricht dann der LED-Baueinheit im Scheinwerfer oder zumindest einem Teil davon. Da die vorzugsweise im PWM-Betrieb angesteuerten Halbleiterschalter in dieser integrierten Ausführungsform räumlich sehr benachbart zu den LEDs angeordnet sind und die Bypassleitungen entsprechend kurz sind, ist die elekt- romagnetische Störabstrahlung der gesamten Schaltungsanordnung insgesamt gering. Hinsichtlich der Integration ist es besonders vorteilhaft, wenn auch noch die Steuereinheit auf dem Träger angeordnet ist.In an advantageous embodiment, the bypass circuits with the semiconductor switches are arranged together with the LEDs on a support, for example a printed circuit board. This carrier then corresponds to the LED assembly in the headlight or at least a part thereof. Since the semiconductor switches, which are preferably activated in PWM mode, are arranged spatially very close to the LEDs in this integrated embodiment and the bypass lines are correspondingly short, the electrical overall electromagnetic radiation of the entire circuit arrangement is low. With regard to the integration, it is particularly advantageous if the control unit is also arranged on the carrier.
In der zentralen Lichtsteuereinheit wird anhand von bestimmten Eingangsgrößen (z.B. Lichtschalterstellung, Blinkersignal, oder Sensorsignale von verschiedenen Sensoren wie z.B. Lenkwinkelsensor oder Gierratensensor, Fahrgeschwindigkeitssensor, Lichtsensor oder Kamera etc.) anhand zuvor definierter Algorithmen festgelegt, welche LED bzw. welche Gruppen/Teilmengen von LEDs mit welcher Lichtintensität (oder relativen Lichtintensität) eingeschaltet werden sollen, um für eine bestimmte Situation die optimale Lichtverteilung und Reichweite zu erzielen. Diese Informationen werden dann über die Steuersignalleitungen an die Steuereinheit der LED-Baueinheit übertragen, die dann die den LEDs zugeordneten Halbleiterschalter (HS) mit einem der gewünschten Lichtintensität entsprechenden PWM-Signal beaufschlagt. In the central light control unit is determined based on specific input variables (eg light switch position, turn signal, or sensor signals from various sensors such as steering angle sensor or yaw rate sensor, vehicle speed sensor, light sensor or camera, etc.) based on previously defined algorithms, which LED or which groups / subsets of LEDs with which light intensity (or relative light intensity) should be switched on in order to achieve the optimum light distribution and range for a specific situation. This information is then transmitted via the control signal lines to the control unit of the LED assembly, which then applied to the LEDs associated semiconductor switch (HS) with a desired light intensity corresponding PWM signal.

Claims

Patentansprüche claims
Schaltungsanordnung zur elektrischen Ansteuerung eines Kraftfahrzeug- Scheinwerfers, dessen Lichtquelle aus zwei oder mehr Leuchtdioden (LEDs) besteht, dadurch gekennzeichnet, dassCircuit arrangement for the electrical control of a motor vehicle headlamp whose light source consists of two or more light-emitting diodes (LEDs), characterized in that
- mindestens eine Reihenschaltung mit zwei oder mehr Leuchtdioden vorgesehen ist, wobei die Reihenschaltung an eine Konstantstromquelle angeschlossen ist,at least one series circuit having two or more LEDs is provided, the series circuit being connected to a constant current source,
- mindestens einer Leuchtdiode eine steuerbare Bypass-Schaltung zur Steuerung der Lichtintensität dieser Leuchtdiode parallel geschaltet ist,at least one light-emitting diode is connected in parallel with a controllable bypass circuit for controlling the light intensity of this light-emitting diode,
- eine Steuereinheit zur Ansteuerung der Bypass-Schaltung vorgesehen ist.- A control unit for controlling the bypass circuit is provided.
2. Schaltungsanordnung nach Anspruch 1 , dadurch gekennzeichnet, dass die Steuereinheit und die mindestens eine Bypass-Schaltung gemeinsam mit den Leuchtdioden in einer an dem Scheinwerfer angeordneten Baueinheit integriert sind.2. A circuit arrangement according to claim 1, characterized in that the control unit and the at least one bypass circuit are integrated together with the light emitting diodes in a arranged on the headlight assembly.
3. Schaltungsanordnung nach Anspruch 2, dadurch gekennzeichnet, dass die mindestens eine Bypass-Schaltung gemeinsam mit den Leuchtdioden auf einem Träger angeordnet ist.3. Circuit arrangement according to claim 2, characterized in that the at least one bypass circuit is arranged together with the light emitting diodes on a support.
4. Schaltungsanordnung nach Anspruch 3, dadurch gekennzeichnet, dass auch die Steuereinheit auf dem Träger angeordnet ist.4. Circuit arrangement according to claim 3, characterized in that the control unit is also arranged on the carrier.
5. Schaltungsanordung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die Ansteuerung der mindestens einen Bypass-Schaltung über einen Halbleiterschalter, insbesondere über einen Feldeffekttransistor erfolgt, der von der Steuereinheit angesteuert wird.5. Circuit arrangement according to one of the preceding claims, characterized in that the control of the at least one bypass circuit via a semiconductor switch, in particular via a field effect transistor, which is controlled by the control unit.
6. Schaltungsanordnung nach Anspruch 5, dadurch gekennzeichnet, dass der Halbleiterschalter in einer Schaltposition eine vollständige Umleitung des Stromes um die zugehörige Leuchtdiode über den Bypass und in der anderen Schaltposition eine Sperrung des Bypasses bewirkt.6. Circuit arrangement according to claim 5, characterized in that the semiconductor switch in a switching position causes a complete diversion of the current to the associated light-emitting diode via the bypass and in the other switching position, a blocking of the bypass.
7. Schaltungsanordnung nach Anspruch 6, dadurch gekennzeichnet, dass der Halbleiterschalter über ein pulsweitenmoduliertes Steuersignal angesteuert wird, wobei die Lichtintensität der zugehörigen Leuchtdiode über das Verhältnis der Pulseinschaltdauer zur Pulsausschaltdauer eingestellt wird.7. Circuit arrangement according to claim 6, characterized in that the semiconductor switch is driven by a pulse width modulated control signal, wherein the light intensity of the associated light emitting diode is set via the ratio of Pulseinschaltdauer to Pulsausschaltdauer.
8. Schaltungsanordnung nach Anspruch 6, dadurch gekennzeichnet, dass der Bypass über den Halbleiterschalter nur eine teilweise Umleitung des Stromes um die zugehörige Leuchtdiode bewirkt.8. Circuit arrangement according to claim 6, characterized in that the bypass via the semiconductor switch causes only a partial diversion of the current to the associated light emitting diode.
9. Schaltungsanordnung nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass9. Circuit arrangement according to one of the preceding claims, characterized in that
- zwei oder mehr Leuchtdioden einer Reihenschaltung jeweils eine steuerbare Bypass-Schaltung parallel geschaltet ist,two or more light-emitting diodes of a series connection each have a controllable bypass circuit connected in parallel,
- die jeweiligen Bypass-Schaltungen getrennt voneinander von der Steuereinheit ansteuerbar sind. - The respective bypass circuits are controlled separately from each other by the control unit.
PCT/EP2007/006001 2006-07-08 2007-07-06 Circuit arrangement for electrically triggering a motor vehicle headlight WO2008006518A1 (en)

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