EP1330143A2 - Operating device for light emitting diodes - Google Patents

Operating device for light emitting diodes Download PDF

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Publication number
EP1330143A2
EP1330143A2 EP03000960A EP03000960A EP1330143A2 EP 1330143 A2 EP1330143 A2 EP 1330143A2 EP 03000960 A EP03000960 A EP 03000960A EP 03000960 A EP03000960 A EP 03000960A EP 1330143 A2 EP1330143 A2 EP 1330143A2
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EP
European Patent Office
Prior art keywords
electronic switch
leds
emitting diodes
circuit arrangement
pull
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP03000960A
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German (de)
French (fr)
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EP1330143B1 (en
EP1330143A3 (en
Inventor
Ugo Francescutti
Giovanni Scilla
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Osram GmbH
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Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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Publication of EP1330143A2 publication Critical patent/EP1330143A2/en
Publication of EP1330143A3 publication Critical patent/EP1330143A3/en
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Publication of EP1330143B1 publication Critical patent/EP1330143B1/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]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]

Definitions

  • the invention relates to a circuit arrangement according to the preamble of Claim 1. It is in particular an electronic control gear a device for setting the effective value for the operation of light-emitting diodes contains the operating current of the LEDs, this device pulsed mode of operation.
  • the following circuit arrangement is for operating light-emitting diodes, further abbreviated as LED common: an energy source, e.g. a public supply network or a battery that feeds an electronic converter that has a supply voltage provides.
  • the LEDs are usually connected to two connecting cables connected to the supply voltage. There can be one or more LEDs on one Supply voltage can be operated. Several LEDs are usually in series switched and form a so-called strand. Several lines can be connected in parallel cross connections are also possible between the strands. Become most LEDs are connected to one supply voltage, so they are combined into so-called LED modules that also include current limiting resistors can contain. Together with voltage regulation in the electronic converter a desired operating current for connected LEDs is realized.
  • the circuit arrangements in question are not only for the operation of LEDs suitable. It is also possible to use organic light emitting devices (OLED). to operate.
  • OLED organic light emitting devices
  • the electronic switch and an associated control circuit can be put together combined with the electronic converter into one unit in one housing his. But it is also possible to use the electronic switch and the control circuit to be designed as a separate dimming unit in a separate housing. This dimming unit can then be used for setting the effective value of the operating current of the LEDs is desired between the electronic converters and the LEDs are switched.
  • the pulse rate at which the electronic switch is opened and closed is usually above a frequency at which the human eye is isolated It is able to distinguish between light pulses. In practice, frequencies come from 100Hz to several kilohertz for use.
  • the connecting line into which no electronic switch is inserted forms a pole of an output voltage.
  • the other pole of the output voltage is the one facing away from the supply voltage Pole of the electronic switch.
  • the output voltage is the LEDs or LED modules supplied. It has a rectangular shape Fundamental frequency equal to the above Pulse rate is. Especially with long connection lines this can lead to electromagnetic incompatibility or radio interference to lead. To prevent this and to comply with relevant regulations (e.g. CISPR 15) adhering to them often requires a lot of effort in the form of filters and shields.
  • the output voltage is made up of a DC component and an AC component together.
  • the amplitude of the alternating component the output voltage is briefly below with the amplitude of the output voltage designated.
  • the maximum value of the output voltage is set when the is closed electronic switch and is by the value of the supply voltage specified. By definition, the amplitude of the output voltage is half the difference between the maximum value and minimum value of the output voltage. Given The maximum value thus determines the minimum value the amplitude of the output voltage and thus the strength of the electromagnetic interference. The smaller the The minimum value of the output voltage is, the stronger the electromagnetic Disorders.
  • the minimum value of the output voltage is essentially determined by two variables: a load impedance when the electronic is switched off Switch and an off-impedance of the electronic switch.
  • the load impedance at switched off electronic switch is composed of the impedance of the Connection cables and the impedance of the LEDs with a very low operating current.
  • Below the off-impedance of the electronic switch is the impedance of the electronic one Understand switch in the open state.
  • Lead impedances to electronic switches can be considered in the off-impedance, play but generally doesn't matter. Both sizes, the load impedance when switched off electronic switches and the off-impedance are subject to strong variations conditionally e.g.
  • the value of the minimum value is not exactly determined.
  • the amount of off-impedance is orders of magnitude the amount of load impedance surpasses. It can also be assumed that the real part of the concerned Impedances essentially determine the properties of these impedances. Approximately the output voltage thus drops when the electronic switch is open to the value 0. It follows that the amplitude of the Output voltage is substantially equal to half the supply voltage.
  • a pulldown device is used in parallel with the electronic switch connected.
  • the value of the pulldown device's resistance should be be selected so that in the parallel connection of pulldown device and off-impedance The off-impedance can be neglected, so variations in the off-impedance have no influence on the output voltage.
  • Pulldown device can set the minimum value of the output voltage become. According to the invention, the minimum value will deviate significantly from 0 and thus be significantly larger than in the prior art. This is compared to the Prior art reduced the amplitude of the output voltage, resulting in an inventive Reduction of electromagnetic interference leads.
  • the value of the resistance of the pulldown device must not be so be small that it is on the order of the resistance of the electronic switch is in the closed state. In this case the effect would be electronic Switch and thus the effect of the pulsed operation limited.
  • the electronic switch is opened, the operating current of the LEDs is reduced.
  • a reduction factor becomes the operating current when the electronic switch is open described.
  • a limitation of the pulsed operation is then according to the invention not given if the value of the lowering factor is at least 10.
  • the lowering factor is greater than 1000 so there is no effective reduction of the invention given electromagnetic incompatibilities.
  • the cheapest implementation of the pulldown device according to the invention is a Pull-down resistor.
  • an adjustable Pulldown resistor can be realized.
  • This can take the form of one or more Semiconductors, e.g. FETs happen that operate as voltage controlled resistors become. Also a resistance that cannot be changed continuously, e.g. B. in the form of a switchable resistor cascade is conceivable.
  • the adjustable pulldown resistor is controlled by a control device. This records a current lowering factor and sets the adjustable pulldown resistance so that a given one Lowering factor is observed.
  • the Control device To record the current reduction factor, the Control device the operating current of the LED or the current through the electronic Switch and the adjustable pulldown resistor fed. Because the lowering factor is defined by the operating current, the sole detection of the Operating current to determine the reduction factor. Because the operating current is essentially the sum of the current through the electronic switch and the current due to the adjustable pulldown resistor, it is sufficient for these two currents to determine the lowering factor. Approximately, when closed electronic switch the current through the electronic switch be set equal to the operating current. A statement about the lowering factor the amplitude of the output voltage can also be evaluated. In the event that the supply voltage is constant, the voltage is sufficient evaluate over the electronic switch.
  • the pull-up device is inexpensive due to a pull-up resistor realized.
  • the value of the pullup resistor must be between the values lie, which are for the amount of load impedance when open and when closed result in electronic switch.
  • the electronic switch When the electronic switch is closed the operating current through the LEDs is high and thus the load impedance is low.
  • the value of the pull-up resistance is chosen to be greater than this low load impedance, thus the electronic converter essentially supplies energy to the LEDs delivers and not to the pullup resistor.
  • the electronic switch open With the electronic switch open the operating current through the LEDs is low and therefore due to the non-linear ones Properties of the LEDs, the load impedance high.
  • the value of the pullup resistance must be lower than this high load impedance, so that according to the invention the variations in high load impedance do not affect the amplitude of the Affect output voltage.
  • Both pullup and pulldown resistance do not necessarily have to be through one individual resistance can be realized.
  • the realization is also possible by connecting several resistors in parallel or in series. Parallel to the resistors z. B. to reduce the slope of the output voltage reactances must also be switched.
  • resistances are indicated by the letter R, switches by the Letter S, tensions through the letter V, and connection points through the letter J followed by a number.
  • FIG. 1 is a block diagram of a circuit arrangement according to the invention shown for the operation of LEDs.
  • An electronic converter 1 delivers to J1, J2 a supply voltage V1 to a dimming module 2.
  • Das Dimming module 2 supplies an output voltage V2 at the connection points J3, J4 to the LEDs 3.
  • a piece of a first connection line from the electronic converter 1 to the LEDs 3 is made by a connection from the connection point J1 to Junction J2 formed in the dimming module 2.
  • a piece of a second connection line from the electronic converter 1 to the LEDs 3 leads from the connection point J2 2 via an electronic switch S 1 in the dimming module to the connection point J4.
  • a control circuit 4 controls the electronic switch S1 in such a way that that the LEDs 3 are operated in a pulsed mode of operation.
  • a pulldown resistor R2 is connected in parallel with the electronic switch S1.
  • the function and sizing rules for R2 are shown in the section the invention. This applies equally to an invention Pullup resistor, which is connected between J3 and J4 in dimming module 2.
  • FIG. 2 shows the course of the output voltage V2 over the time t of a circuit arrangement for operating LEDs according to the prior art (without R1 and R2).
  • the course is essentially rectangular.
  • the maximum value of V2 is always assumed when the electronic switch S1 is closed, the minimum value of V2 is always assumed when S1 is open.
  • the maximum value of V2 essentially corresponds to the supply voltage V1 that the electronic converter 1 supplies.
  • the minimum value of V2 is approximately 0. This essentially results in the value for the amplitude of V2 according to the prior art V 1 2
  • FIG. 3 shows the course of the output voltage V2 over the time t of a circuit arrangement according to the invention for operating LEDs (with R1 and R2).
  • the course is essentially rectangular.
  • the maximum value of V2 is always assumed when the electronic switch S1 is closed, the minimum value of V2 is always assumed when S1 is open.
  • the maximum value of V2 essentially corresponds to the supply voltage V1 that the electronic converter 1 supplies.
  • FIG. 4 is a block diagram of a circuit arrangement according to the invention shown for the operation of LEDs with adjustable regulated pulldown resistor.
  • the pulldown resistor R2 is adjustable in FIG Resistance executed, which is controlled by a control device 5.
  • the control device 5 sets the pulldown resistor R2 so that one in the control device stored specified reduction value is observed.
  • the control device 5 receives a measured value for the operating current of the LEDs supplied.
  • the amplitude of the alternating component of the operating current of the LEDs is a measure of the current reduction value.
  • the current reduction value can thus be in the Control device 5 can be determined.

Landscapes

  • Led Devices (AREA)
  • Electronic Switches (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Led Device Packages (AREA)
  • Lighting Device Outwards From Vehicle And Optical Signal (AREA)

Abstract

The arrangement has an electronic switch for the LED operating current and a pull-down device in parallel with the switch whose resistance is dimensioned so that the ratio of the operating current with the switch closed to the operating current with the switch open is described by a reduction factor of at least 10.

Description

Technisches GebietTechnical field

Die Erfindung geht aus von einer Schaltungsanordnung gemäß dem Oberbegriff des Anspruchs 1. Es handelt sich dabei insbesondere um ein elektronisches Betriebsgerät zum Betrieb von Leuchtdioden das eine Einrichtung zum Einstellen des Effektivwerts des Betriebsstroms der Leuchtdioden enthält, wobei diese Einrichtung eine gepulste Arbeitsweise aufweist.The invention relates to a circuit arrangement according to the preamble of Claim 1. It is in particular an electronic control gear a device for setting the effective value for the operation of light-emitting diodes contains the operating current of the LEDs, this device pulsed mode of operation.

Stand der TechnikState of the art

Zum Betrieb von Leuchtdioden, weiterhin mit LED abgekürzt, ist folgende Schaltungsanordnung verbreitet: Eine Energiequelle, z.B. ein öffentliches Versorgungsnetz oder eine Batterie, speist einen elektronischen Konverter, der eine Versorgungsspannung bereitstellt. Die LEDs sind in der Regel über zwei Anschlussleitungen mit der Versorgungsspannung verbunden. Es können eine oder mehrere LEDs an einer Versorgungsspannung betrieben werden. Mehrere LEDs werden in der Regel in Serie geschaltet und bilden einen sog. Strang. Mehrere Stränge können parallel geschaltet werden, wobei zwischen den Strängen auch Querverbindungen möglich sind. Werden mehrere LEDs an einer Versorgungsspannung angeschlossen, so sind sie meist zu sog. LED-Modulen zusammengefasst, die auch Strombegrenzungswiderstände enthalten können. Zusammen mit einer Spannungsregelung im elektronischen Konverter wird damit ein gewünschter Betriebsstrom für angeschlossene LEDs realisiert. Die in Rede stehenden Schaltungsanordnungen sind nicht nur zum Betrieb von LED geeignet. Es ist auch möglich, damit sog. Organic Light Emitting Devices (OLED) zu betreiben.The following circuit arrangement is for operating light-emitting diodes, further abbreviated as LED common: an energy source, e.g. a public supply network or a battery that feeds an electronic converter that has a supply voltage provides. The LEDs are usually connected to two connecting cables connected to the supply voltage. There can be one or more LEDs on one Supply voltage can be operated. Several LEDs are usually in series switched and form a so-called strand. Several lines can be connected in parallel cross connections are also possible between the strands. Become most LEDs are connected to one supply voltage, so they are combined into so-called LED modules that also include current limiting resistors can contain. Together with voltage regulation in the electronic converter a desired operating current for connected LEDs is realized. The circuit arrangements in question are not only for the operation of LEDs suitable. It is also possible to use organic light emitting devices (OLED). to operate.

Oft besteht der Wunsch den Effektivwert des Betriebsstroms der LEDs einstellen zu können und zwar ohne in den elektronischen Konverter einzugreifen. Dies ermöglicht das Dimmen der angeschlossen LEDs oder die Anschlussmöglichkeit verschiedener Typen oder einer unterschiedlichen Anzahl von LEDs an ein und derselben Versorgungsspannung. Die Einstellmöglichkeit des Effektivwerts des Betriebsstroms der LEDs wird durch Einfügen eines elektronischen Schalters in eine Anschlussleitung realisiert. In welche Anschlussleitung der elektronische Schalter eingefügt wird, ist prinzipiell beliebig. In der deutschen Patentanmeldung mit dem Anmeldeaktenzeichen 10136658.2 (Scilla) ist die besagte Einstellmöglichkeit des Effektivwerts des Betriebsstroms der LEDs beschrieben. Der elektronische Schalter kann kostengünstig als MOSFET ausgeführt sein. Durch Öffnen des Schalters wird der Betriebsstrom der LEDs unterbrochen. Durch periodisches Öffnen und Schließen des elektronischen Schalters wird eine gepulste Arbeitsweise für den Betrieb der LEDs realisiert. Das Verhältnis der Dauer des geschlossnen Zustands des Schalters zur Dauer des geöffneten Zustands legt ein Tastverhältnis fest. Durch ein geeignetes Tastverhältnis kann ein gewünschter Effektivwert für den Betriebsstrom der Leuchtdioden eingestellt werden. Der Maximalwert des Betriebsstroms der LEDs, der sich bei eingeschaltetem elektronischen Schalter einstellt, wird von der Versorgungsspannung vorgegeben.There is often a desire to set the effective value of the operating current of the LEDs can do this without intervening in the electronic converter. this makes possible dimming the connected LEDs or connecting different ones Types or a different number of LEDs on one and the same Supply voltage. The possibility of setting the effective value of the operating current The LEDs are switched on by inserting an electronic switch into a connection line realized. In which connection line the electronic switch is inserted, is in principle arbitrary. In the German patent application with the application file number 10136658.2 (Scilla) is the said setting option for the effective value of the Operating current of the LEDs described. The electronic switch can be inexpensive be designed as a MOSFET. By opening the switch, the operating current of the LEDs interrupted. By periodically opening and closing the electronic Switch is a pulsed mode of operation for the operation of the LEDs. The Ratio of the duration of the closed state of the switch to the duration of the open State defines a duty cycle. With a suitable duty cycle a desired effective value for the operating current of the LEDs is set become. The maximum value of the operating current of the LEDs, which is when the electronic switch, is determined by the supply voltage.

Der elektronische Schalter und eine dazugehörige Ansteuerschaltung kann zusammen mit dem elektronischen Konverter zu einer Einheit in einem Gehäuse zusammengefasst sein. Es ist aber auch möglich, den elektronischen Schalter und die Ansteuerschaltung als separate Dimmeinheit in einem separaten Gehäuse auszubilden. Diese Dimmeinheit kann dann, wenn eine Einstellmöglichkeit für den Effektivwert des Betriebsstroms der LEDs gewünscht wird, zwischen den elektronischen Konverter und die LEDs geschaltet werden.The electronic switch and an associated control circuit can be put together combined with the electronic converter into one unit in one housing his. But it is also possible to use the electronic switch and the control circuit to be designed as a separate dimming unit in a separate housing. This dimming unit can then be used for setting the effective value of the operating current of the LEDs is desired between the electronic converters and the LEDs are switched.

Die Pulsfrequenz, mit der der elektronische Schalter geöffnet und geschlossen wird, liegt üblicherweise oberhalb einer Frequenz, bei der das menschliche Auge einzelne Lichtpulse voneinander zu unterscheiden vermag. In der Praxis kommen Frequenzen von 100Hz bis zu mehreren Kilohertz zur Anwendung. Die Anschlussleitung, in die kein elektronischer Schalter eingefügt ist, bildet einen Pol einer Ausgangsspannung. Den anderen Pol der Ausgangsspannung bildet der der Versorgungsspannung abgewandte Pol des elektronischen Schalters. Die Ausgangsspannung wird den LEDs bzw. LED-Modulen zugeführt. Sie hat einen rechteckförmigen Verlauf dessen Grundfrequenz gleich der o. g. Pulsfrequenz ist. Insbesondere bei langen Anschlussleitungen kann dies zu elektromagnetischen Unverträglichkeiten oder Funkstörungen führen. Um dies zu unterbinden und um einschlägige Vorschriften (z.B. CISPR 15) einzuhalten, ist oft ein hoher Aufwand in Form von Filtern und Abschirmungen nötig.The pulse rate at which the electronic switch is opened and closed is usually above a frequency at which the human eye is isolated It is able to distinguish between light pulses. In practice, frequencies come from 100Hz to several kilohertz for use. The connecting line into which no electronic switch is inserted, forms a pole of an output voltage. The other pole of the output voltage is the one facing away from the supply voltage Pole of the electronic switch. The output voltage is the LEDs or LED modules supplied. It has a rectangular shape Fundamental frequency equal to the above Pulse rate is. Especially with long connection lines this can lead to electromagnetic incompatibility or radio interference to lead. To prevent this and to comply with relevant regulations (e.g. CISPR 15) adhering to them often requires a lot of effort in the form of filters and shields.

Darstellung der ErfindungPresentation of the invention

Es ist Aufgabe der vorliegenden Erfindung, eine Schaltungsanordnung gemäß dem Oberbegriff des Anspruchs 1 bereitzustellen, die eine gepulste Arbeitsweise der LEDs bewerkstelligt, jedoch gegenüber dem Stand der Technik geringere elektromagnetische Unverträglichkeiten oder Funkstörungen erzeugt.It is an object of the present invention to provide a circuit arrangement according to the Provide preamble of claim 1, which is a pulsed operation of the LEDs accomplished, but lower electromagnetic compared to the prior art Incompatibility or radio interference.

Diese Aufgabe wird durch eine Schaltungsanordnung mit den Merkmalen des Oberbegriffs des Anspruchs 1 durch die Merkmale des kennzeichnenden Teils des Anspruchs 1 gelöst. Besonders vorteilhafte Ausgestaltungen finden sich in den abhängigen Ansprüchen.This object is achieved by a circuit arrangement with the features of the preamble of claim 1 by the features of the characterizing part of the claim 1 solved. Particularly advantageous configurations can be found in the dependent ones Claims.

Wie stark die von einer in Rede stehenden Schaltungsanordnung erzeugten elektromagnetischen Störungen sind, hängt in erster Linie von der Amplitude des Wechselanteils der o.g. Ausgangsspannung ab. Die Ausgangsspannung setzt sich aus einem Gleichanteil und einem Wechselanteil zusammen. Die Amplitude des Wechselanteils der Ausgangsspannung wird im folgenden kurz mit Amplitude der Ausgangsspannung bezeichnet. Der Maximalwert der Ausgangsspannung stellt sich bei geschlossenem elektronischen Schalter ein und ist durch den Wert der Versorgungsspannung vorgegeben. Die Amplitude der Ausgangsspannung ist definitionsgemäß die Hälfte der Differenz aus Maximalwert und Minimalwert der Ausgangsspannung. Bei gegebenem Maximalwert bestimmt also der Minimalwert die Amplitude der Ausgangsspannung und somit die Stärke der elektromagnetischen Störungen. Je kleiner der Minimalwert der Ausgangsspannung ist, um so stärker sind die elektromagnetischen Störungen.How strong the electromagnetic generated by a circuit arrangement in question Disturbances primarily depend on the amplitude of the alternating component the above Output voltage. The output voltage is made up of a DC component and an AC component together. The amplitude of the alternating component the output voltage is briefly below with the amplitude of the output voltage designated. The maximum value of the output voltage is set when the is closed electronic switch and is by the value of the supply voltage specified. By definition, the amplitude of the output voltage is half the difference between the maximum value and minimum value of the output voltage. Given The maximum value thus determines the minimum value the amplitude of the output voltage and thus the strength of the electromagnetic interference. The smaller the The minimum value of the output voltage is, the stronger the electromagnetic Disorders.

Im Stand der Technik wird der Minimalwert der Ausgangsspannung im wesentlichen durch zwei Größen bestimmt: Eine Lastimpedanz bei ausgeschaltetem elektronischen Schalter und eine Off-Impedanz des elektronischen Schalters. Die Lastimpedanz bei ausgeschaltetem elektronischen Schalter setzt sich zusammen aus der Impedanz der Anschlussleitungen und der Impedanz der LEDs bei sehr kleinem Betriebsstrom. Unter der Off-Impedanz des elektronischen Schalters ist die Impedanz des elektronischen Schalters im geöffneten Zustand zu verstehen. Zuleitungsimpedanzen zum elektronischen Schalter können in der Off-Impedanz berücksichtigt werden, spielen aber im allgemeinen keine Rolle. Beide Größen, die Lastimpedanz bei ausgeschaltetem elektronischen Schalter und die Off-Impedanz unterliegen starken Variationen bedingt z.B. durch Exemplarstreuung, Temperatur, Alterung und Auswahl der LEDs so dass der Wert des Minimalwerts nicht genau bestimmt ist. Generell gilt jedoch, dass der Betrag der Off-Impedanz um Größenordnungen den Betrag der Lastimpedanz übertrifft. Auch kann angenommen werden, dass der Realteil der betreffenden Impedanzen im wesentlichen die Eigenschaften dieser Impedanzen bestimmt. Näherungsweise fällt somit die Ausgangsspannung bei geöffnetem elektronischen Schalter auf den Wert 0 ab. Es ergibt sich also, dass im Stand der Technik die Amplitude der Ausgangsspannung im wesentlichen gleich der Hälfte der Versorgungsspannung ist.In the prior art, the minimum value of the output voltage is essentially determined by two variables: a load impedance when the electronic is switched off Switch and an off-impedance of the electronic switch. The load impedance at switched off electronic switch is composed of the impedance of the Connection cables and the impedance of the LEDs with a very low operating current. Below the off-impedance of the electronic switch is the impedance of the electronic one Understand switch in the open state. Lead impedances to electronic switches can be considered in the off-impedance, play but generally doesn't matter. Both sizes, the load impedance when switched off electronic switches and the off-impedance are subject to strong variations conditionally e.g. through sample distribution, temperature, aging and selection of the LEDs so the value of the minimum value is not exactly determined. In general, however, that the amount of off-impedance is orders of magnitude the amount of load impedance surpasses. It can also be assumed that the real part of the concerned Impedances essentially determine the properties of these impedances. Approximately the output voltage thus drops when the electronic switch is open to the value 0. It follows that the amplitude of the Output voltage is substantially equal to half the supply voltage.

Erfindungsgemäß wird parallel zum elektronischen Schalter eine Pulldown-Einrichtung geschaltet. Der Wert des Widerstands der Pulldown-Einrichtung sollte so gewählt sein, dass in der Parallelschaltung aus Pulldown-Einrichtung und Off-Impedanz die Off-Impedanz vernachlässigt werden kann, damit Variationen der Offimpedanz keinen Einfluss auf die Ausgangsspannung haben. Durch die erfindungsgemäße Pulldown-Einrichtung kann der Minimalwert der Ausgangsspannung eingestellt werden. Der Minimalwert wird erfindungsgemäß deutlich von 0 abweichen und somit wesentlich größer sein als im Stand der Technik. Damit wird gegenüber dem Stand der Technik die Amplitude der Ausgangsspannung reduziert, was zu einer erfindungsgemäßen Reduzierung der elektromagnetischen Störungen führt.According to the invention, a pulldown device is used in parallel with the electronic switch connected. The value of the pulldown device's resistance should be be selected so that in the parallel connection of pulldown device and off-impedance The off-impedance can be neglected, so variations in the off-impedance have no influence on the output voltage. By the invention Pulldown device can set the minimum value of the output voltage become. According to the invention, the minimum value will deviate significantly from 0 and thus be significantly larger than in the prior art. This is compared to the Prior art reduced the amplitude of the output voltage, resulting in an inventive Reduction of electromagnetic interference leads.

Der Wert des Widerstands der Pulldown-Einrichtung darf erfindungsgemäß nicht so klein sein, dass er in der Größenordnung des Widerstandes des elektronischen Schalters im geschlossenen Zustand liegt. In diesem Fall wäre die Wirkung des elektronischen Schalters und somit die Wirkung des gepulsten Betriebs eingeschränkt. Durch Öffnen des elektronischen Schalters wird der Betriebsstrom der LEDs abgesenkt. Durch das Verhältnis des Betriebsstroms bei geschlossenem elektronischen Schalter zum Betriebsstroms bei geöffnetem elektronischen Schalter wird ein Absenkfaktor beschrieben. Eine Einschränkung des gepulsten Betriebs ist erfindungsgemäß dann nicht gegeben, wenn der Wert des Absenkfaktors mindestens 10 ist. Wird der Absenkfaktor größer als 1000 so ist keine wirksame erfindungsgemäße Reduzierung der elektromagnetischen Unverträglichkeiten mehr gegeben.According to the invention, the value of the resistance of the pulldown device must not be so be small that it is on the order of the resistance of the electronic switch is in the closed state. In this case the effect would be electronic Switch and thus the effect of the pulsed operation limited. By When the electronic switch is opened, the operating current of the LEDs is reduced. By the ratio of the operating current when the electronic switch is closed a reduction factor becomes the operating current when the electronic switch is open described. A limitation of the pulsed operation is then according to the invention not given if the value of the lowering factor is at least 10. The lowering factor is greater than 1000 so there is no effective reduction of the invention given electromagnetic incompatibilities.

Die erfindungsgemäß kostengünstigste Realisierung der Pulldown-Einrichtung ist ein Pulldown-Widerstand. Soll jedoch der Wert des Absenkfaktors konstant bleiben, auch wenn sich Betriebsparameter wie Lastimpedanz oder Versorgungsspannung ändern, so muss die Pulldown-Einrichtung erfindungsgemäß durch einen einstellbaren Pulldown-Widerstand realisiert werden. Dies kann in Form eines oder mehrerer Halbleiter, z.B. FETs geschehen, die als spannungsgesteuerte Widerstände betrieben werden. Auch ein nicht kontinuierlich veränderbarer Widerstand, z. B. in Form einer schaltbaren Widerstandskaskade, ist denkbar. Der einstellbare Pulldown-Widerstand wird von einer Regeleinrichtung gesteuert. Diese erfasst einen aktuellen Absenkfaktor und stellt den einstellbaren Pulldown-Widerstand so ein, dass ein vorgegebener Absenkfaktor eingehalten wird. Zur Erfassung des aktuellen Absenkfaktors wird der Regeleinrichtung der Betriebsstrom der LED oder der Strom durch den elektronischen Schalter und den einstellbaren Pulldown-Widerstand zugeführt. Da der Absenkfaktor durch den Betriebsstrom definiert ist, genügt die alleinige Erfassung des Betriebsstroms, um den Absenkfaktor zu ermitteln. Da der Betriebsstrom im wesentlichen die Summe des Stroms durch den elektronischen Schalter und des Stromes durch den einstellbaren Pulldown-Widerstand ist, genügt es auch diese beiden Ströme zu erfassen, um den Absenkfaktor zu ermitteln. Näherungsweise kann bei geschlossenem elektronischen Schalter der Strom durch den elektronischen Schalter gleich dem Betriebsstrom gesetzt werden. Um eine Aussage über den Absenkfaktor treffen zu können kann auch die Amplitude der Ausgangsspannung ausgewertet werden. Für den Fall, dass die Versorgungsspannung konstant ist, genügt es, die Spannung über dem elektronischen Schalter auszuwerten.The cheapest implementation of the pulldown device according to the invention is a Pull-down resistor. However, if the value of the lowering factor should remain constant, even if there are operating parameters such as load impedance or supply voltage change, the pulldown device according to the invention by an adjustable Pulldown resistor can be realized. This can take the form of one or more Semiconductors, e.g. FETs happen that operate as voltage controlled resistors become. Also a resistance that cannot be changed continuously, e.g. B. in the form of a switchable resistor cascade is conceivable. The adjustable pulldown resistor is controlled by a control device. This records a current lowering factor and sets the adjustable pulldown resistance so that a given one Lowering factor is observed. To record the current reduction factor, the Control device the operating current of the LED or the current through the electronic Switch and the adjustable pulldown resistor fed. Because the lowering factor is defined by the operating current, the sole detection of the Operating current to determine the reduction factor. Because the operating current is essentially the sum of the current through the electronic switch and the current due to the adjustable pulldown resistor, it is sufficient for these two currents to determine the lowering factor. Approximately, when closed electronic switch the current through the electronic switch be set equal to the operating current. A statement about the lowering factor the amplitude of the output voltage can also be evaluated. In the event that the supply voltage is constant, the voltage is sufficient evaluate over the electronic switch.

Durch die erfindungsgemäße Pulldown-Einrichtung sind die oben beschriebenen Variationen der Amplitude der Ausgangsspannung, die durch die Off-Impedanz des elektronischen Schalters bedingt sind, eliminiert. Was bleibt, sind Variationen, die durch die Lastimpedanz verursacht werden. Diese können erfindungsgemäß durch eine Pullup-Einrichtung eliminiert werden, der an die Ausgangsspannung angeschlossen wird und damit parallel zu den LEDs geschaltet ist. Die oben ausgeführten Dimensionierungsregeln für die Pulldown-Einrichtung gelten auch bei Vorhandensein der Pullup-Einrichtung.Through the pulldown device according to the invention, those described above are Variations in the amplitude of the output voltage caused by the off-impedance of the electronic switch are eliminated. What remains are variations that caused by the load impedance. According to the invention, these can be carried out by a pullup device can be eliminated that is connected to the output voltage and is therefore connected in parallel to the LEDs. The above Sizing rules for the pulldown facility also apply if they exist the pullup facility.

Erfindungsgemäß wird die Pullup-Einrichtung kostengünstig durch einen Pullup-Widerstand realisiert. Der Wert des Pullup-Widerstands muss zwischen den Werten liegen, die sich für den Betrag der Lastimpedanz bei geöffnetem und bei geschlossenem elektronischen Schalter ergeben. Bei geschlossenem elektronischen Schalter ist der Betriebsstrom durch die LEDs hoch und somit die Lastimpedanz niedrig. Vorteilhaft wird der Wert des Pullup-Widerstands größer gewählt als diese niedrige Lastimpedanz, damit der elektronische Konverter im wesentlichen Energie an die LEDs liefert und nicht an den Pullup-Widerstand. Bei geöffnetem elektronischen Schalter ist der Betriebsstrom durch die LEDs niedrig und somit, bedingt durch die nichtlinearen Eigenschaften der LEDs, die Lastimpedanz hoch. Der Wert des Pullup-Widerstands muss niedriger sein als diese hohe Lastimpedanz, damit sich erfindungsgemäß die Variationen der hohen Lastimpedanz nicht auf die Amplitude der Ausgangsspannung auswirken.According to the invention, the pull-up device is inexpensive due to a pull-up resistor realized. The value of the pullup resistor must be between the values lie, which are for the amount of load impedance when open and when closed result in electronic switch. When the electronic switch is closed the operating current through the LEDs is high and thus the load impedance is low. Advantageous the value of the pull-up resistance is chosen to be greater than this low load impedance, thus the electronic converter essentially supplies energy to the LEDs delivers and not to the pullup resistor. With the electronic switch open the operating current through the LEDs is low and therefore due to the non-linear ones Properties of the LEDs, the load impedance high. The value of the pullup resistance must be lower than this high load impedance, so that according to the invention the variations in high load impedance do not affect the amplitude of the Affect output voltage.

Sowohl Pullup- als auch Pulldown-Widerstand müssen nicht zwingend durch einen einzelnen Widerstand realisiert sein. Selbstverständlich ist auch die Realisierung durch Parallel- oder Serienschaltung von mehreren Widerständen möglich. Parallel zu den Widerständen können z. B. zur Reduzierung der Flankensteilheit der Ausgangsspannung auch Reaktanzen geschaltet sein.Both pullup and pulldown resistance do not necessarily have to be through one individual resistance can be realized. Of course, the realization is also possible by connecting several resistors in parallel or in series. Parallel to the resistors z. B. to reduce the slope of the output voltage reactances must also be switched.

Kurze Beschreibung der ZeichnungenBrief description of the drawings

Im folgenden soll die Erfindung anhand eines Ausführungsbeispiels unter Bezugnahme auf Zeichnungen näher erläutert werden. Es zeigen:

Figur 1
ein Blockschaltbild einer erfindungsgemäßen Schaltungsanordnung zum Betrieb von LEDs,
Figur 2
den zeitlichen Verlauf der Ausgangsspannung einer Schaltungsanordnung zum Betrieb von LEDs 'nach dem Stand der Technik,
Figur 3
den zeitlichen Verlauf der Ausgangsspannung einer erfindungsgemäßen Schaltungsanordnung zum Betrieb von LEDs,
Figur 4
ein Blockschaltbild einer erfindungsgemäßen Schaltungsanordnung zum Betrieb von LEDs mit einstellbarem geregeltem Pulldown-Widcrstand.
In the following the invention will be explained in more detail using an exemplary embodiment with reference to drawings. Show it:
Figure 1
2 shows a block diagram of a circuit arrangement according to the invention for operating LEDs,
Figure 2
the time course of the output voltage of a circuit arrangement for operating LEDs according to the prior art,
Figure 3
the time course of the output voltage of a circuit arrangement according to the invention for operating LEDs,
Figure 4
a block diagram of a circuit arrangement according to the invention for the operation of LEDs with adjustable regulated pulldown resistance.

Im folgenden werden Widerstände durch den Buchstaben R, Schalter durch den Buchstaben S, Spannungen durch den Buchstaben V, und Verbindungsstellen durch den Buchstaben J jeweils gefolgt von einer Zahl bezeichnet.In the following, resistances are indicated by the letter R, switches by the Letter S, tensions through the letter V, and connection points through the letter J followed by a number.

Bevorzugte Ausführung der ErfindungPreferred embodiment of the invention

In Figur 1 ist ein Blockschaltbild einer erfindungsgemäßen Schaltungsanordnung zum Betrieb von LEDs dargestellt. Ein elektronischer Konverter 1 liefert an den Verbindungsstellen J1, J2 eine Versorgungsspannung V1 an ein Dimmmodul 2. Das Dimmmodul 2 liefert an den Verbindungsstellen J3, J4 eine Ausgangsspannung V2 an die LEDs 3. Ein Stück einer ersten Anschlussleitung vom elektronischen Konverter 1 zu den LEDs 3 wird durch eine Verbindung von der Verbindungsstelle J1 zur Verbindungsstelle J2 im Dimmmodul 2 gebildet. Ein Stück einer zweiten Anschlussleitung vom elektronischen Konverter 1 zu den LEDs 3 führt von der Verbindungsstelle J2 2 über einen elektronischen Schalter S 1 im Dimmmodul zur Verbindungsstelle J4. Eine Ansteuerschaltung 4 steuert den elektronischen Schalter S1 derart, dass die LEDs 3 in einer gepulsten Arbeitsweise betrieben werden. Erfindungsgemäß ist parallel zum elektronischen Schalter S1 ein Pulldown-Widerstand R2 geschaltet. Die Funktion und die Dimensionierungsregeln für R2 sind dem Abschnitt zur Darstellung der Erfindung zu entnehmen. Dies gilt gleichermaßen für einen erfindungsgemäßen Pullup-widerstand, der im Dimmmodul 2 zwischen J3 und J4 geschaltet ist.In Figure 1 is a block diagram of a circuit arrangement according to the invention shown for the operation of LEDs. An electronic converter 1 delivers to J1, J2 a supply voltage V1 to a dimming module 2. Das Dimming module 2 supplies an output voltage V2 at the connection points J3, J4 to the LEDs 3. A piece of a first connection line from the electronic converter 1 to the LEDs 3 is made by a connection from the connection point J1 to Junction J2 formed in the dimming module 2. A piece of a second connection line from the electronic converter 1 to the LEDs 3 leads from the connection point J2 2 via an electronic switch S 1 in the dimming module to the connection point J4. A control circuit 4 controls the electronic switch S1 in such a way that that the LEDs 3 are operated in a pulsed mode of operation. According to the invention a pulldown resistor R2 is connected in parallel with the electronic switch S1. The function and sizing rules for R2 are shown in the section the invention. This applies equally to an invention Pullup resistor, which is connected between J3 and J4 in dimming module 2.

Figur 2 zeigt den Verlauf der Ausgangsspannung V2 über der Zeit t einer Schaltungsanordnung zum Betrieb von LEDs nach dem Stand der Technik (ohne R1 und R2). Der Verlauf ist im wesentlichen rechteckförmig. Der Maximalwert von V2 wird immer angenommen, wenn der elektronische Schalter S1 geschlossen ist, der Minimalwert von V2 wird immer angenommen wenn S1 geöffnet ist. Der Maximalwert von V2 entspricht im wesentlichen der Versorgungsspannung V1, die der elektronische Konverter 1 liefert. Der Minimalwert von V2 ist näherungsweise 0. Damit ergibt sich für die Amplitude von V2 nach dem Stand der Technik im wesentlichen der Wert V1 2 FIG. 2 shows the course of the output voltage V2 over the time t of a circuit arrangement for operating LEDs according to the prior art (without R1 and R2). The course is essentially rectangular. The maximum value of V2 is always assumed when the electronic switch S1 is closed, the minimum value of V2 is always assumed when S1 is open. The maximum value of V2 essentially corresponds to the supply voltage V1 that the electronic converter 1 supplies. The minimum value of V2 is approximately 0. This essentially results in the value for the amplitude of V2 according to the prior art V 1 2

Figur 3 zeigt den Verlauf der Ausgangsspannung V2 über der Zeit t einer erfindungsgemäßen Schaltungsanordnung zum Betrieb von LEDs (mit R1 und R2). Wie in Figur 2 ist der Verlauf im wesentlichen rechteckförmig. Der Maximalwert von V2 wird immer angenommen, wenn der elektronische Schalter S1 geschlossen ist, der Minimalwert von V2 wird immer angenommen wenn S1 geöffnet ist. Der Maximalwert von V2 entspricht im wesentlichen der Versorgungsspannung V1, die der elektronische Konverter 1 liefert. Der Minimalwert ist V3, wobei bei Beachtung der o. g. Anmerkungen zur Dimensionierung von R1 und R2 im wesentlichen gilt: V3 = V1 R1 R1 + R2 FIG. 3 shows the course of the output voltage V2 over the time t of a circuit arrangement according to the invention for operating LEDs (with R1 and R2). As in FIG. 2, the course is essentially rectangular. The maximum value of V2 is always assumed when the electronic switch S1 is closed, the minimum value of V2 is always assumed when S1 is open. The maximum value of V2 essentially corresponds to the supply voltage V1 that the electronic converter 1 supplies. The minimum value is V3, whereby when observing the above comments on the dimensioning of R1 and R2 the following essentially applies: V 3 = V 1 R 1 R 1 + R 2

Damit ergibt sich für die Amplitude von V2 im wesentlichen ein erfindungsgemäßer Wert von V1 2 R2 R1 + R2 This essentially results in a value according to the invention for the amplitude of V2 V 1 2 R 2 R 1 + R 2

Insbesondere für den Fall, dass R1 wesentlich größer ist als R2, ergibt sich erfindungsgemäß eine starke Reduzierung der Amplitude von V2 gegenüber dem Stand der Technik.In particular, in the event that R1 is significantly larger than R2, this results in accordance with the invention a sharp reduction in the amplitude of V2 compared to the state of the technique.

In Figur 4 ist ein Blockschaltbild einer erfindungsgemäßen Schaltungsanordnung zum Betrieb von LEDs mit einstellbarem geregeltem Pulldown-Widerstand dargestellt. Gegenüber Figur 1 ist in Figur 4 der Pulldown-Widerstand R2 als einstellbarer Widerstand ausgeführt, der von einer Regeleinrichtung 5 gesteuert wird. Die Regeleinrichtung 5 stellt den Pulldown-Widerstand R2 so ein, dass ein in der Regeleinrichtung abgelegter vorgegebener Absenkwert eingehalten wird. Durch eine Messeinrichtung 6 wird der Regeleinrichtung 5 ein Messwert für den Betriebsstrom der LEDs zugeführt. Die Amplitude des Wechselanteils des Betriebsstroms der LEDs ist ein Maß für den aktuellen Absenkwert. Der aktuelle Absenkwert kann damit in der Regeleinrichtung 5 ermittelt werden.FIG. 4 is a block diagram of a circuit arrangement according to the invention shown for the operation of LEDs with adjustable regulated pulldown resistor. Compared to FIG. 1, the pulldown resistor R2 is adjustable in FIG Resistance executed, which is controlled by a control device 5. The control device 5 sets the pulldown resistor R2 so that one in the control device stored specified reduction value is observed. By a measuring device 6, the control device 5 receives a measured value for the operating current of the LEDs supplied. The amplitude of the alternating component of the operating current of the LEDs is a measure of the current reduction value. The current reduction value can thus be in the Control device 5 can be determined.

Claims (8)

Schaltungsanordnung zum Betrieb von Leuchtdioden, die einen Betriebsstrom aufweisen, der im wesentlichen durch einen elektronischen Schalter fließt, dadurch gekennzeichnet, dass parallel zum elektronischen Schalter eine Pulldown-Einrichtung geschaltet ist, deren Widerstand einen Wert aufweist, der so dimensioniert ist, dass das Verhältnis des Betriebsstroms bei geschlossenem elektronischen Schalter zum Betriebsstroms bei geöffnetem elektronischen Schalter durch einen Absenkfaktor beschrieben wird, der mindestens den Wert 10 annimmt.Circuit arrangement for operating light-emitting diodes, which have an operating current which essentially flows through an electronic switch, characterized in that a pull-down device is connected in parallel with the electronic switch, the resistance of which has a value which is dimensioned such that the ratio of the Operating current when the electronic switch is closed to the operating current when the electronic switch is open is described by a reduction factor that takes at least the value 10. Schaltungsanordnung zum Betrieb von Leuchtdioden gemäß Anspruch 1 dadurch gekennzeichnet, dass parallel zu den Leuchtdioden eine Pullup-Einrichtung geschaltet ist.Circuit arrangement for operating light-emitting diodes according to claim 1, characterized in that a pull-up device is connected in parallel with the light-emitting diodes. Schaltungsanordnung zum Betrieb von Leuchtdioden gemäß Anspruch 1 dadurch gekennzeichnet, dass die Pulldown-Einrichtung durch einen Pulldown-Widerstand realisiert ist.Circuit arrangement for operating light-emitting diodes according to claim 1, characterized in that the pulldown device is realized by a pulldown resistor. Schaltungsanordnung zum Betrieb von Leuchtdioden gemäß Anspruch 1 dadurch gekennzeichnet, dass die Pulldown-Einrichtung durch einen einstellbaren Pulldown-Widerstand realisiert ist, wobei eine Regeleinrichtung den Wert des Pulldown-Widerstands so einstellt, dass ein vorgegebener Absenkfaktor eingehalten wird.Circuit arrangement for operating light-emitting diodes according to claim 1, characterized in that the pull-down device is realized by an adjustable pull-down resistor, a control device sets the value of the pull-down resistor so that a predetermined reduction factor is maintained. Schaltungsanordnung zum Betrieb von Leuchtdioden gemäß Anspruch 4 dadurch gekennzeichnet, dass der einstellbare Pulldown-Widerstand durch mindestens ein Halbleiterbauelement realisiert ist.Circuit arrangement for operating light-emitting diodes according to claim 4, characterized in that the adjustable pull-down resistor is realized by at least one semiconductor component. Schaltungsanordnung zum Betrieb von Leuchtdioden gemäß Anspruch 4 dadurch gekennzeichnet, dass der einstellbare Pulldown-Widerstand durch mehrere schaltbare Widerstände realisiert ist.Circuit arrangement for operating light-emitting diodes according to claim 4, characterized in that the adjustable pull-down resistor is realized by a plurality of switchable resistors. Schaltungsanordnung zum Betrieb von Leuchtdioden gemäß Anspruch 2 dadurch gekennzeichnet, dass die dass die Pullup-Einrichtung durch einen Pullup-Widerstand realisiert ist. Circuit arrangement for operating light-emitting diodes according to claim 2, characterized in that the pull-up device is realized by a pull-up resistor. Schaltungsanordnung zum Betrieb von Leuchtdioden gemäß Anspruch 1 dadurch gekennzeichnet, dass der elektronischer Schalter durch einen MOSFET realisiert ist.Circuit arrangement for operating light-emitting diodes according to claim 1, characterized in that the electronic switch is realized by a MOSFET.
EP03000960A 2002-01-17 2003-01-16 Operating device for light emitting diodes Expired - Lifetime EP1330143B1 (en)

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DE10201779A DE10201779A1 (en) 2002-01-17 2002-01-17 Control gear for light emitting diodes

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CN102545650B (en) * 2010-12-31 2016-12-28 澳大利亚克林普斯有限公司 Power-switching circuit

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EP1330143B1 (en) 2006-11-22
CN1441631A (en) 2003-09-10
ATE346480T1 (en) 2006-12-15
EP1330143A3 (en) 2004-02-11
CN100474995C (en) 2009-04-01
DE50305720D1 (en) 2007-01-04
DE10201779A1 (en) 2003-07-31

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