EP1330946B1 - Circuit arrangement for operating several gas discharge lamps - Google Patents

Circuit arrangement for operating several gas discharge lamps Download PDF

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Publication number
EP1330946B1
EP1330946B1 EP01982352A EP01982352A EP1330946B1 EP 1330946 B1 EP1330946 B1 EP 1330946B1 EP 01982352 A EP01982352 A EP 01982352A EP 01982352 A EP01982352 A EP 01982352A EP 1330946 B1 EP1330946 B1 EP 1330946B1
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EP
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Prior art keywords
gas discharge
circuitry arrangement
lamps
voltage
lamp
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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.)
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EP01982352A
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German (de)
French (fr)
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EP1330946A1 (en
Inventor
Dietmar Klien
Markus Mayrhofer
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Tridonicatco GmbH and Co KG
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Tridonicatco GmbH and Co KG
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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
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/36—Controlling
    • H05B41/38—Controlling the intensity of light
    • H05B41/39—Controlling the intensity of light continuously
    • H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor

Definitions

  • the present invention relates to a circuit arrangement for operating at least two gas discharge lamps according to the preamble of claim 1.
  • each only one drive only gas discharge lamp is that a large part of the Components of the ballast, such as the rectifier, the Harmonic filter, the control circuit and the inverter for operating multiple Lamps can be used simultaneously.
  • the inverter and the load circuit of a known two-lamp ballast which is disclosed in EP 0 490 329 A1, are shown schematically in FIG. 4 and will be briefly explained below.
  • the inverter is formed by two controllable switches S1 and S2, which are arranged in a half-bridge arrangement, at the input of which a DC supply voltage V BUS is present. From a control circuit 1, the two switches S1 and S2 are driven so that they alternately open and shoot, so that at the midpoint of the half-bridge results in a high-frequency AC voltage U ac .
  • This alternating voltage is supplied to the load circuit, which initially has on the input side a series resonant circuit consisting of an inductance L a and a capacitor C r .
  • the two gas discharge lamps LA1 and LA2 are each connected in parallel via a coupling capacitor C k1 or C k2 .
  • the two gas discharge lamps LA1 and LA2 is preceded by a balancing transformer L bal whose windings are traversed by the two lamp currents. This occurs in opposite directions, so that in the case of deviations of the current amplitudes, a magnetization is produced which induces a voltage in the windings, which in turn acts in a symmetrizing manner.
  • the balancing transformer L bal thus component tolerances and lamp tolerances and different temperature conditions, which would result in that the two lamps LA1 and LA2 burn with different brightness, can be compensated to a certain extent.
  • the balancing effect of the transformer L bal is limited and does not ensure complete alignment of the lamp currents.
  • the lamps are connected in parallel at low currents, which result at low dimming levels, since the voltage drop across the balancing transformer can only be a fraction of the burning voltage of the lamps. This is particularly evident at lower temperatures, where the burning voltage reaches a maximum with small lamp currents.
  • the two lamps are to be operated at a brightness which corresponds to a certain nominal current I SOLL .
  • I SOLL nominal current
  • both lamps are not identical, but have slightly shifted characteristic curves U arc1 and U arc2 , as shown in FIG.
  • the second lamp generally requires a slightly higher burning voltage U arc2 than the first lamp for a given current. Therefore, in order to be able to operate both lamps with the nominal current I SOLL , two different burning voltages U SOLL1 and U SOLL2 would be required.
  • the ballast with the inverter only provides a voltage value U SOLL1 , which is determined in the example shown by the lamp with the lower burning voltage, ie by the first lamp with the characteristic U arc1 , this voltage U SOLL1 is also at the second Lamp on.
  • the second lamp does not assume the desired current value I SOLL , but possibly forms a second operating point with a different current value I arc2 and thus of course also with a different brightness.
  • the second lamp with the higher operating voltage may not be able to form a fixed operating point and, as a result, it will disappear.
  • the control of the inverter always takes place in the case of the ballast shown in FIG. 4 after that lamp LA1 or LA2, which currently has the lower lamp current.
  • the ballast on two detection circuits 2 1 and 2 2 each detecting the current flowing through a lamp LA1 and LA2 current by determining the drop across a measuring resistor R SENS1 or R SENS2 voltage.
  • the actual values V IST1 and V IST2 generated by the two detection circuits 2 1 and 2 2 are then fed to a comparison circuit 3, which selects the correspondingly lower value and forwards the final actual value V IST to the control circuit 1 for controlling the inverter.
  • From DE 42 43 955 A1 is a ballast for at least one parallel operated Gas discharge lamp pair known, showing the features of claim 1.
  • n is integer and greater 1
  • gas discharge lamps with a operated with a single inverter, which is fed with a DC voltage and generates a variable in their frequency AC voltage, the one on the Output of the inverter arranged load circuit is supplied.
  • the load circuit contains one consisting of an inductance and a capacitance Series resonant circuit and the n to the common node between the Inductance and the capacity of connected gas discharge lamps. Further contains the load circuit (n-1) balancing transformers for balancing the currents of two gas discharge lamps each.
  • the load circuit points to each Gas discharge lamp on a DC power supply line, respectively between the output side terminal of the winding of the balancing transformer and the gas discharge lamp attacks and over each gas discharge lamp DC is supplied.
  • This additional direct current preferably corresponds approximately to half of the nominal 1% current at 25 ° C - 35 ° C. He causes, even in the event that due to the predetermined AC voltage can not form a stable operating point, none of Lights go out.
  • the additional direct current also prevents this Occurrence of so-called running layers.
  • the measures according to the invention can extinguish the lamps reliably prevented. However, it may be due to more asymmetrical Wiring and lamp capacities come to large brightness differences, since the balancing transformers attempt the relatively large currents and consequently in a lamp with less wiring capacity an additional active current is generated. To avoid this and a better one Symmetrization of the lamp currents can, according to another Development of the invention, the two windings of a balancing transformer each by a series connection of a capacitor and a resistor be connected to each other. This has the consequence that the balancing effect of Transformers is reduced for small lamp currents, without causing the DC sources are affected. The reduction of the balancing effect works only on the AC components of the lamp voltage, so only on that part, which at low levels of dimming is predominantly asymmetrical Wiring capacity is affected.
  • the circuit according to the invention is characterized in that it in a simple manner be extended from a two-lamp system to a multi-flame system can. In addition, it is no longer necessary for each lamp its own Provide detection circuit for measuring the lamp current. Rather, it is sufficient to use only a single detection circuit, which the Sum of the active powers of the arranged in the load circuit gas discharge lamps detected and generates a corresponding actual value. Based on a comparison between this actual value and a predetermined setpoint can then Inverters are controlled. The capture of the sum of the active services can For example, in a half-bridge inverter in a simple way take place that arranged over a arranged at the base of the half-bridge measuring resistor declining voltage is determined.
  • the invention proposed DC power supply lines with the in Series to the lamps switched resistors, which input side to a common supply voltage can also be connected multi-lamp systems are used in which no Balanced transformers are provided.
  • a corresponding circuit arrangement is the subject of claim 9.
  • the circuit arrangement shown in FIG. 1 is similar in its basic structure to the known circuit shown in FIG. Again, only one single inverter consisting of two controllable switches S1 and S2 is provided for operating the two gas discharge lamps LA1 and LA2.
  • the arranged in a half-bridge arrangement switches S1 and S2 are supplied with a DC voltage V BUS and generate by alternately opening and closing a high-frequency AC voltage U ac , which is supplied to the load circuit.
  • the load circuit contains the series resonant circuit consisting of the inductance L a and the capacitance C r , at the center of which the two lamps LA 1 and LA 2 are connected via two coupling capacitors C k1 and C k2 .
  • the lamps LA1 and LA2 are preceded by a balancing transformer L bal .
  • the DC power supply lines according to the invention are each connected to a point between the lamp LA1 or LA2 and the output side of the corresponding winding of the balancing transformer L bal . They each contain a resistor R dc1 or R dc2 connected in series to the corresponding lamp LA1 or LA2 and are connected on the input side to a common DC voltage source. The resistance values for the two resistors R dc1 and R dc2 are identical.
  • the DC voltage source is formed in the example shown by a connected to the output of the inverter diode D1 and a grounded capacitor C dc as a low-pass filter, which form of the high-frequency AC voltage U ac a smoothed DC voltage U dc .
  • the direct current supplied to the second lamp LA2 results analogously.
  • the two resistors R dc1 and R dc2 are designed so that the additional direct current in about half of the nominal 1% current at 25 ° C corresponds to 35 ° C.
  • the recovery of the DC voltage U dc from the AC voltage U ac of the inverter has the further advantage that after switching off the inverter and the lamps LA1 and LA2 supplied DC power is deactivated, so that both lamps LA1, LA2 are turned off safely.
  • the direct current supplied to the lamps LA1, LA2 also prevents the occurrence of so-called running layers.
  • the balancing effect of the transformer L bal only works up to a certain dimming level. At brightness values below this dimming level, the lamp current is so low that capacitive currents that are greater than the lamp currents themselves can arise. These capacitive currents can arise, for example, due to the fact that the supply lines of the lamps are laid asymmetrically, as a result of which additional wiring capacities C par and thus capacitive currents I par occur, as shown schematically in the second lamp LA2. If these capacitive currents I par are greater than the lamp currents, the balancing transformer L bal reacts in such a way that the asymmetry is increased. The lamp LA1, which does not have the additional wiring capacity, is then supplied with an additional active current I arc1 , which can be estimated in the following way: I arc 1 ⁇ I arc 2 2 + I par 2
  • the balancing effect of the transformer L bal is to be reduced for low lamp currents, without this affecting the DC sources.
  • This is achieved in that the two output-side terminals of the windings of the balancing transformer L bal by a frequency-dependent impedance, which consists in the present example of the series connection of a resistor R bal and a capacitor C bal , are interconnected. This connection allows a certain balance of small asymmetries.
  • the reduction of the balancing effect has an effect only on the AC component of the lamp voltage, ie only on that part which is responsible for the capacitive currents at small dimming levels.
  • FIG. 1 The effect of the circuit according to the invention is shown schematically in FIG.
  • the graph shown here shows the voltage applied to the lamps LA1 and LA2 and time-varying lamp voltage U arc1 and U arc2 .
  • U ac1 or U ac2 is still supplied to both lamps, since they are now DC-decoupled, they can assume a different DC voltage component U dc1 or U dc2 .
  • each lamp can exactly take on the voltage that it would have to form for the given brightness value or lamp current. This provides the ability to drive both lamps through a single inverter and still operate both at the desired brightness.
  • FIG. 3 illustrates the extension of the system to three gas discharge lamps LA1, LA2 and LA3.
  • the extension consists merely in that now several balancers L bal12 and L bal23 are used, which respectively symmetrize the currents of two lamps LA1 and LA2 or LA2 and LA3.
  • L bal12 and L bal23 are used, which respectively symmetrize the currents of two lamps LA1 and LA2 or LA2 and LA3.
  • R or R bal12 bal23 to cause the output-side terminals of the balancing transformers bal12 L and L bal23 over the previously described series combination of a resistor R or R bal12 bal23 and a capacitance C bal12 or C bal23 connected to a decoupling of the DC components.
  • An extension of the system to n gas discharge lamps is then only that (n-1) balancing transformers are used, which each symmetrize the currents of two lamps.

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  • Circuit Arrangements For Discharge Lamps (AREA)

Abstract

A circuitry arrangement for operating n gas discharge lamps, n being a whole number greater than 1, includes a single inverter, fed with d.c. voltage, for generating an a.c. voltage alterable in its frequency, delivered to a load circuit arranged at the inverter's output. The load circuit includes a series resonant circuit of an inductance and capacitance, n gas discharge lamps connected to a common node point between the inductance and capacitance, which lamps are connected in parallel to one another, and (n-1) balancing transformers for balancing currents in two gas discharge lamps. The load circuit further has for each gas discharge lamp at least one d.c. current supply line, connected between an output side terminal of a corresponding balancing transformer winding and gas discharge lamp and via which there is delivered to each gas discharge lamp a d.c. current, so as to avoid an unintended extinguishing of a lamp.

Description

Die vorliegende Erfindung betrifft eine Schaltungsanordnung zum Betreiben von mindestens zwei Gasentladungslampen nach dem Oberbegriff des Anspruches 1.The present invention relates to a circuit arrangement for operating at least two gas discharge lamps according to the preamble of claim 1.

Durch den Einsatz sogenannter zwei- oder mehrflammiger Vorschaltgeräte kann in einem gewissen Umfang eine Reduzierung des Schaltungsaufwands erzielt werden. Der Vorteil gegenüber der Verwendung von Vorschaltgeräten, die jeweils lediglich eine einzige Gasentladungslampe ansteuern, besteht darin, daß ein Großteil der Komponenten des Vorschaltgeräts, beispielsweise der Gleichrichter, das Oberwellenfilter, die Steuerschaltung sowie der Wechselrichter zum Betreiben mehrerer Lampen gleichzeitig verwendet werden kann.Through the use of so-called two- or multi-lamp ballasts can in To a certain extent, a reduction of the circuit complexity can be achieved. Of the Advantage over the use of ballasts, each only one drive only gas discharge lamp, is that a large part of the Components of the ballast, such as the rectifier, the Harmonic filter, the control circuit and the inverter for operating multiple Lamps can be used simultaneously.

Der Wechselrichter und der Lastkreis eines bekannten zweiflammigen Vorschaltgeräts, das in der EP 0 490 329 A1 offenbart ist, sind schematisch in Figur 4 dargestellt und sollen im Folgenden kurz erläutert werden. Der Wechselrichter wird durch zwei steuerbare Schalter S1 und S2 gebildet, die in einer Halbbrückenanordnung, an deren Eingang eine Versorgungsgleichspannung VBUS anliegt, angeordnet sind. Von einer Steuerschaltung 1 werden die beiden Schalter S1 und S2 derart angesteuert, daß sie abwechselnd öffnen und schießen, so daß sich am Mittelpunkt der Halbbrücke eine hochfrequente Wechselspannung Uac ergibt. Diese Wechselspannung wird dem Lastkreis zugeführt, der zunächst eingangsseitig einen aus einer Induktivität La und einem Kondensator Cr bestehenden Serienresonanzkreis aufweist. An den gemeinsamen Knotenpunkt zwischen der Induktivität La und der Kapazität Cr sind die beiden Gasentladungslampen LA1 und LA2 jeweils über einen Koppelkondensator Ck1 bzw. Ck2 parallel angeschlossen.The inverter and the load circuit of a known two-lamp ballast, which is disclosed in EP 0 490 329 A1, are shown schematically in FIG. 4 and will be briefly explained below. The inverter is formed by two controllable switches S1 and S2, which are arranged in a half-bridge arrangement, at the input of which a DC supply voltage V BUS is present. From a control circuit 1, the two switches S1 and S2 are driven so that they alternately open and shoot, so that at the midpoint of the half-bridge results in a high-frequency AC voltage U ac . This alternating voltage is supplied to the load circuit, which initially has on the input side a series resonant circuit consisting of an inductance L a and a capacitor C r . At the common node between the inductance L a and the capacitance C r , the two gas discharge lamps LA1 and LA2 are each connected in parallel via a coupling capacitor C k1 or C k2 .

Darüber hinaus ist den beiden Gasentladungslampen LA1 und LA2 ein Symmetriertransformator Lbal vorgeschaltet, dessen Wicklungen von den beiden Lampenströmen durchflossen werden. Dies geschieht gegensinnig, so daß bei Abweichungen der Stromamplituden eine Magnetisierung entsteht, die in den Wicklungen eine Spannung induziert, welche wiederum symmetrierend wirkt. Durch den Symmetriertransformator Lbal können somit Bauteiltoleranzen sowie Lampentoleranzen und unterschiedliche Temperaturbedingungen, welche zur Folge haben würden, daß die beiden Lampen LA1 und LA2 mit unterschiedlicher Helligkeit brennen, zu einem gewissen Grad ausgeglichen werden. In addition, the two gas discharge lamps LA1 and LA2 is preceded by a balancing transformer L bal whose windings are traversed by the two lamp currents. This occurs in opposite directions, so that in the case of deviations of the current amplitudes, a magnetization is produced which induces a voltage in the windings, which in turn acts in a symmetrizing manner. By the balancing transformer L bal thus component tolerances and lamp tolerances and different temperature conditions, which would result in that the two lamps LA1 and LA2 burn with different brightness, can be compensated to a certain extent.

Die symmetrierende Wirkung des Transformators Lbal ist allerdings beschränkt und gewährleistet keine vollständige Angleichung der Lampenströme. Beispielsweise sind die Lampen bei niedrigen Strömen, die sich bei kleinen Dimmpegeln ergeben, praktisch parallel geschaltet, da der Spannungsabfall am Symmetriertransformator nur einen Bruchteil der Brennspannung der Lampen betragen kann. Dies zeigt sich besonders bei tieferen Temperaturen, wo die Brennspannung bei kleinen Lampenströmen ein Maximum erreicht.However, the balancing effect of the transformer L bal is limited and does not ensure complete alignment of the lamp currents. For example, the lamps are connected in parallel at low currents, which result at low dimming levels, since the voltage drop across the balancing transformer can only be a fraction of the burning voltage of the lamps. This is particularly evident at lower temperatures, where the burning voltage reaches a maximum with small lamp currents.

Dieser Fall ist in Figur 5 dargestellt. Dabei sollen die beiden Lampen bei einer Helligkeit betrieben werden, die einem bestimmten Sollstrom ISOLL entspricht. Aufgrund von Toleranzen sind allerdings beide Lampe nicht identisch, sondern weisen leicht gegeneinander verschobene Kennlinien Uarc1 bzw. Uarc2 auf, wie sie in Figur 5 dargestellt sind. So erfordert beispielsweise die zweite Lampe bei einem vorgegebenen Strom grundsätzlich eine etwas höhere Brennspannung Uarc2 als die erste Lampe. Um daher beide Lampen mit dem Sollstrom ISOLL betreiben zu können, würden zwei unterschiedliche Brennspannungen USOLL1 und USOLL2 benötigt werden. Da jedoch das Vorschaltgerät mit dem Wechselrichter lediglich einen Spannungswert USOLL1 zur Verfügung stellt, der im dargestellten Beispiel durch die Lampe mit der niedrigeren Brennspannung, also durch die erste Lampe mit der Kennlinie Uarc1 bestimmt wird, liegt diese Spannung USOLL1 auch an der zweiten Lampe an. Als Folge davon nimmt die zweite Lampe nicht den gewünschten Stromwert ISOLL an, sondern bildet möglicherweise einen zweiten Arbeitspunkt mit einem anderen Stromwert Iarc2 und damit natürlich auch mit einer anderen Helligkeit aus. Es besteht allerdings auch die Gefahr, daß die zweite Lampe mit der höheren Brennspannung möglicherweise gar keinen festen Arbeitspunkt ausbilden kann und in Folge davon verlischt.This case is shown in FIG. In this case, the two lamps are to be operated at a brightness which corresponds to a certain nominal current I SOLL . Due to tolerances, however, both lamps are not identical, but have slightly shifted characteristic curves U arc1 and U arc2 , as shown in FIG. For example, the second lamp generally requires a slightly higher burning voltage U arc2 than the first lamp for a given current. Therefore, in order to be able to operate both lamps with the nominal current I SOLL , two different burning voltages U SOLL1 and U SOLL2 would be required. However, since the ballast with the inverter only provides a voltage value U SOLL1 , which is determined in the example shown by the lamp with the lower burning voltage, ie by the first lamp with the characteristic U arc1 , this voltage U SOLL1 is also at the second Lamp on. As a result, the second lamp does not assume the desired current value I SOLL , but possibly forms a second operating point with a different current value I arc2 and thus of course also with a different brightness. However, there is also the danger that the second lamp with the higher operating voltage may not be able to form a fixed operating point and, as a result, it will disappear.

Um daher bei niedrigen Helligkeitswerten das Verlöschen einer der beiden Lampen LA1 oder LA2 zu vermeiden, erfolgt bei dem in Fig. 4 dargestellten Vorschaltgerät die Regelung des Wechselrichters immer nach derjenigen Lampe LA1 bzw. LA2, die gerade den niedrigeren Lampenstrom aufweist. Hierfür weist das Vorschaltgerät zwei Erfassungsschaltungen 21 und 22 auf, die jeweils den durch eine Lampe LA1 bzw. LA2 fließenden Strom erfassen, indem sie die über einen Meßwiderstand RSENS1 bzw. RSENS2 abfallende Spannung bestimmen. Die von den beiden Erfassungsschaltungen 21 und 22 erzeugten Istwerte VIST1 und VIST2 werden dann einer Vergleichsschaltung 3 zugeführt, welche den entsprechend niedrigeren Wert auswählt und als endgültigen Istwert VIST an die Steuerschaltung 1 zur Ansteuerung des Wechselrichters weiterleitet.Therefore, in order to avoid the extinction of one of the two lamps LA1 or LA2 at low brightness values, the control of the inverter always takes place in the case of the ballast shown in FIG. 4 after that lamp LA1 or LA2, which currently has the lower lamp current. For this purpose, the ballast on two detection circuits 2 1 and 2 2 , each detecting the current flowing through a lamp LA1 and LA2 current by determining the drop across a measuring resistor R SENS1 or R SENS2 voltage. The actual values V IST1 and V IST2 generated by the two detection circuits 2 1 and 2 2 are then fed to a comparison circuit 3, which selects the correspondingly lower value and forwards the final actual value V IST to the control circuit 1 for controlling the inverter.

Somit ist für jede Lampe eine eigene Erfassungsschaltung notwendig, um zuverlässig gewährleisten zu können, daß keine der beiden Lampen verlöscht. Der schaltungstechnische Aufwand wird hierdurch allerdings wiederum erhöht. Darüber hinaus ist zu berücksichtigen, daß bedingt durch die Schaltkapzitäten der Lampen oder durch die Verdrahtung immer auch ein kapazitiver Strom durch die Lampen fließt. Eine einwandfreie Regelung wird allerdings nur dann gewährleistet, wenn der tatsächliche Wirkanteil des Lampenstroms ermittelt wird. Hierzu sind aufwendige und teure Schaltungen notwendig. Schließlich wird bei den mehrflammigen Systemen, bei denen mehr als zwei Lampen an einen einzigen Wechselrichter angeschlossen sind, eine komplexe Auswahlschaltung zur Auswahl des jeweils niedrigsten Istwerts benötigt.Thus, a separate detection circuit is necessary for each lamp to be reliable to be able to ensure that neither of the two lamps goes out. Of the However, circuit complexity is thereby increased again. About that In addition, it should be noted that due to the switching capacities of the lamps or through the wiring always a capacitive current flows through the lamps. However, a perfect regulation is only guaranteed if the actual effective component of the lamp current is determined. These are elaborate and expensive circuits necessary. Finally, in multi-flame systems, at where more than two lamps are connected to a single inverter, a complex selection circuit for selecting the lowest actual value needed.

Aus der DE 42 43 955 A1 ist ein Vorschaltgerät für mindestens ein parallel betriebenes Gasentladungslampen-Paar bekannt, das die Merkmale des Patentanspruchs 1 zeigt.From DE 42 43 955 A1 is a ballast for at least one parallel operated Gas discharge lamp pair known, showing the features of claim 1.

Aus der US 5 729 095 A ist ein Hochfrequenzvorschaltgerät bekannt.From US 5 729 095 A a high frequency ballast is known.

Aus der US 5 173 643 A ist ein Vorschaltgerät für Lampen in einer Serienschaltung bekannt.From US 5 173 643 A is a ballast for lamps in a series circuit known.

Es ist daher Aufgabe der vorliegenden Erfindung, eine vereinfachte Schaltungsanordnung zum Betreiben von mindestens zwei Gasentladungslampen anzugeben, bei der zuverlässig das Verlöschen einer der Lampen vermieden wird.It is therefore an object of the present invention to provide a simplified Circuit arrangement for operating at least two gas discharge lamps indicate that the extinguishing of one of the lamps is reliably avoided.

Die Aufgabe wird durch eine Schaltungsanordnung mit den Merkmalen von Anspruch 1 gelöst. Es werden n (n ist ganzzahlig und größer 1 ) Gasentladungslampen mit einem einzigen Wechselrichter betrieben, der mit einer Gleichspannung gespeist wird und eine in ihrer Frequenz veränderbare Wechselspannung erzeugt, die einem an dem Ausgang des Wechselrichters angeordneten Lastkreis zugeführt wird. Der Lastkreis enthält dabei einen aus einer Induktivität und einer Kapazität bestehenden Serienresonanzkreis sowie die n an den gemeinsamen Knotenpunkt zwischen der Induktivität und der Kapazität angeschlossenen Gasentladungslampen. Ferner enthält der Lastkreis (n-1) Symmetriertransformatoren zur Symmetrierung der Ströme von jeweils zwei Gasentladungslampen.The object is achieved by a circuit arrangement with the features of claim 1 solved. There are n (n is integer and greater 1) gas discharge lamps with a operated with a single inverter, which is fed with a DC voltage and generates a variable in their frequency AC voltage, the one on the Output of the inverter arranged load circuit is supplied. The load circuit contains one consisting of an inductance and a capacitance Series resonant circuit and the n to the common node between the Inductance and the capacity of connected gas discharge lamps. Further contains the load circuit (n-1) balancing transformers for balancing the currents of two gas discharge lamps each.

Um zu verhindern, daß eine der Lampen verlöscht, weist der Lastkreis für jede Gasentladungslampe eine Gleichstrom-Versorgungsleitung auf, welche jeweils zwischen dem ausgangsseitigen Anschluß der Wicklung des Symmetriertransformators und der Gasentladungslampe angreift und über die jeder Gasentladungslampe ein Gleichstrom zugeführt wird. Somit erhält jede Gasentladungslampe neben der über den Resonanzkreis und dem Wechselrichter zugeführten Wechselspannung zusätzlich eine unabhängige Stromquelle, welche die Lampe mit einem Gleichstrom versorgt. Dieser zusätzliche Gleichstrom entspricht vorzugsweise in etwa der Hälfte des nominalen 1%-Stomes bei 25°C - 35°C. Er bewirkt, daß selbst für den Fall, daß sich aufgrund der vorgegebenen Wechselspannung kein stabiler Arbeitspunkt ausbilden kann, keine der Lampen verlischt. Darüber hinaus verhindert der zusätzliche Gleichstrom auch das Auftreten von sog. laufenden Schichten. To prevent one of the lamps from extinguishing, the load circuit points to each Gas discharge lamp on a DC power supply line, respectively between the output side terminal of the winding of the balancing transformer and the gas discharge lamp attacks and over each gas discharge lamp DC is supplied. Thus receives each gas discharge lamp in addition to the above Resonance circuit and the inverter supplied AC voltage in addition a independent power source, which supplies the lamp with a direct current. This additional direct current preferably corresponds approximately to half of the nominal 1% current at 25 ° C - 35 ° C. He causes, even in the event that due to the predetermined AC voltage can not form a stable operating point, none of Lights go out. In addition, the additional direct current also prevents this Occurrence of so-called running layers.

Weiterbildungen der Erfindung sind Gegenstand der Unteransprüche. So weisen die Gleichstrom-Versorgungsleitungen vorzugsweise jeweils einen in Serie mit der Lampe geschalteten Widerstand auf und sind an ihrem eingangsseitigen Anschluß an eine gemeinsame Versorgungsspannung angeschlossen. Diese Versorgungsspannung kann beispielsweise mit Hilfe einer an den Ausgang des Wechselrichters angeschlossenen Diode gewonnen werden, wobei vorzugsweise zwischen der Diode und den Gleichstrom-Versorgungsleitungen ein mit Masse verbundener Kondensator angeordnet ist.Further developments of the invention are the subject of the dependent claims. So have the DC power lines preferably one in series with the lamp switched resistor on and are at their input side terminal to a common supply voltage connected. This supply voltage can for example, by means of a connected to the output of the inverter Diode are obtained, preferably between the diode and the DC power supply lines arranged a grounded capacitor is.

Durch die erfindungsgemäßen Maßnahmen kann das Verlöschen der Lampen zuverlässig verhindert werden. Allerdings kann es aufgrund asymmetrischer Verdrahtungs- und Lampenkapazitäten zu großen Helligkeitsunterschieden kommen, da der bzw. die Symmetriertransformatoren versuchen, die relativ großen Ströme auszugleichen und in Folge dessen in einer Lampe mit geringerer Verdrahtungskapazität ein zusätzlichen Wirkstrom erzeugt wird. Um dies zu vermeiden und eine bessere Symmetrierung der Lampenströme zu erzielen, können gemäß einer anderen Weiterbildung der Erfindung die beiden Wicklungen eines Symmetriertransformators jeweils durch eine Serienschaltung aus einem Kondensator und einem Widerstand miteinander verbunden werden. Dies hat zur Folge, daß die Symmetrierwirkung des Transformators für kleine Lampenströme reduziert wird, ohne daß dabei die Gleichstromquellen beeinflußt werden. Die Reduktion der Symmetrierwirkung wirkt sich lediglich auf die Wechselstromkomponenten der Lampenspannung aus, also nur auf jenen Teil, der bei kleinen Dimmpegeln maßgeblich durch asymmetrische Verdrahtungskapazitäten beeinflußt wird.The measures according to the invention can extinguish the lamps reliably prevented. However, it may be due to more asymmetrical Wiring and lamp capacities come to large brightness differences, since the balancing transformers attempt the relatively large currents and consequently in a lamp with less wiring capacity an additional active current is generated. To avoid this and a better one Symmetrization of the lamp currents can, according to another Development of the invention, the two windings of a balancing transformer each by a series connection of a capacitor and a resistor be connected to each other. This has the consequence that the balancing effect of Transformers is reduced for small lamp currents, without causing the DC sources are affected. The reduction of the balancing effect works only on the AC components of the lamp voltage, so only on that part, which at low levels of dimming is predominantly asymmetrical Wiring capacity is affected.

Die erfindungsgemäße Schaltung zeichnet sich dadurch aus, daß sie auf einfache Weise von einem zweiflammigen System auf ein mehrflammiges System erweitert werden kann. Darüber hinaus ist es nicht mehr erforderlich, für jede Lampe eine eigene Erfassungsschaltung zum Messen des Lampenstromes vorzusehen. Vielmehr ist es ausreichend, lediglich eine einzige Erfassungsschaltung zu verwenden, welche die Summe der Wirkleistungen der in dem Lastkreis angeordneten Gasentladungslampen erfaßt und einen entsprechenden Istwert erzeugt. Auf Grundlage eines Vergleichs zwischen diesem Istwert und einem vorgegebenen Sollwert kann dann der Wechselrichter angesteuert werden. Die Erfassung der Summe der Wirkleistungen kann beispielsweise bei einem Halbbrückenwechselrichter auf einfache Weise dadurch erfolgen, daß die über einen am Fußpunkt der Halbbrücke angeordneten Meßwiderstand abfallende Spannung bestimmt wird. The circuit according to the invention is characterized in that it in a simple manner be extended from a two-lamp system to a multi-flame system can. In addition, it is no longer necessary for each lamp its own Provide detection circuit for measuring the lamp current. Rather, it is sufficient to use only a single detection circuit, which the Sum of the active powers of the arranged in the load circuit gas discharge lamps detected and generates a corresponding actual value. Based on a comparison between this actual value and a predetermined setpoint can then Inverters are controlled. The capture of the sum of the active services can For example, in a half-bridge inverter in a simple way take place that arranged over a arranged at the base of the half-bridge measuring resistor declining voltage is determined.

Die erfindungsgemäß vorgeschlagenen Gleichstrom-Versorgungsleitungen mit den in Serie zu den Lampen geschalteten Widerständen, welche eingangsseitig an eine gemeinsame Versorgungsspannung angeschlossen sind, können auch bei mehrflammigen Lampensystemen zum Einsatz kommen, bei denen keine Symmetriertransformatoren vorgesehen sind. Eine entsprechende Schaltungsanordnung ist Gegenstand des Anspruches 9.The invention proposed DC power supply lines with the in Series to the lamps switched resistors, which input side to a common supply voltage can also be connected multi-lamp systems are used in which no Balanced transformers are provided. A corresponding circuit arrangement is the subject of claim 9.

Im folgenden soll die Erfindung anhand der beiliegenden Zeichnungen näher erläutert werden. Es zeigen:

Fig. 1
ein Ausführungsbeispiel einer erfindungsgemäßen Schaltungsanordnung für ein zweiflammiges Lampensystem;
Fig. 2
eine Darstellung der Wirkung der erfindungsgemäßen Gleichstrom-Versorgungsleitungen;
Fig. 3
ein Ausführungsbeispiel einer erfindungsgemäßen Schaltungsanordnung für ein dreiflammiges Lampensystem;
Fig. 4
eine bekannte Schaltungsanordnung eines zweiflammigen Lampensystems; und
Fig. 5
eine Darstellung der sich bei Lampen mit verschiedenen Kennlinien ergebenden Effekte.
In the following the invention will be explained in more detail with reference to the accompanying drawings. Show it:
Fig. 1
An embodiment of a circuit arrangement according to the invention for a two-lamp system;
Fig. 2
a representation of the effect of the DC power supply lines according to the invention;
Fig. 3
An embodiment of a circuit arrangement according to the invention for a three-lamp system;
Fig. 4
a known circuit arrangement of a two-lamp system; and
Fig. 5
a representation of the resulting in lamps with different characteristics effects.

Die in Figur 1 dargestellte Schaltungsanordnung ähnelt in ihrem grundsätzlichen Aufbau der in Figur 4 dargestellten bekannten Schaltung. Wiederum ist zum Betreiben der beiden Gasentladungslampen LA1 und LA2 lediglich ein einziger aus zwei steuerbaren Schaltern S1 und S2 bestehender Wechselrichter vorgesehen. Die in einer Halbbrückenanordnung angeordneten Schalter S1 und S2 werden mit einer Gleichspannung VBUS gespeist und erzeugen durch abwechselndes Öffnen und Schließen eine hochfrequente Wechselspannung Uac, die dem Lastkreis zugeführt wird. Der Lastkreis enthält den aus der Induktivität La und der Kapazität Cr bestehenden Serienresonanzkreis, an dessen Mittelpunkt über zwei Koppelkondensaroren Ck1 und Ck2 die beiden Lampen LA1 und LA2 angeschlossen sind. Wiederum ist den Lampen LA1 und LA2 ein Symmetriertransformator Lbal vorgeschaltet.The circuit arrangement shown in FIG. 1 is similar in its basic structure to the known circuit shown in FIG. Again, only one single inverter consisting of two controllable switches S1 and S2 is provided for operating the two gas discharge lamps LA1 and LA2. The arranged in a half-bridge arrangement switches S1 and S2 are supplied with a DC voltage V BUS and generate by alternately opening and closing a high-frequency AC voltage U ac , which is supplied to the load circuit. The load circuit contains the series resonant circuit consisting of the inductance L a and the capacitance C r , at the center of which the two lamps LA 1 and LA 2 are connected via two coupling capacitors C k1 and C k2 . Again, the lamps LA1 and LA2 are preceded by a balancing transformer L bal .

Die erfindungsgemäßen Gleichstrom-Versorgungsleitungen sind jeweils an einen Punkt zwischen der Lampe LA1 bzw. LA2 und der Ausgangsseite der entsprechenden Wicklung des Symmetriertransformators Lbal angeschlossen. Sie enthalten jeweils einen zu der entsprechenden Lampe LA1 bzw. LA2 in Serie geschalteten Widerstand Rdc1 bzw. Rdc2 und sind eingangsseitig an eine gemeinsame Gleichspannungsquelle angeschlossen. Die Widerstandswerte für die beiden Widerstände Rdc1 und Rdc2 sind identisch. Die Gleichspannungsquelle wird im dargestellten Beispiel durch eine an den Ausgang des Wechselrichters angeschlossene Diode D1 sowie einen mit Masse verbundenen Kondensator Cdc als Tiefpaß gebildet, welche aus der hochfrequenten Wechselspannung Uac eine geglättete Gleichspannung Udc bilden.The DC power supply lines according to the invention are each connected to a point between the lamp LA1 or LA2 and the output side of the corresponding winding of the balancing transformer L bal . They each contain a resistor R dc1 or R dc2 connected in series to the corresponding lamp LA1 or LA2 and are connected on the input side to a common DC voltage source. The resistance values for the two resistors R dc1 and R dc2 are identical. The DC voltage source is formed in the example shown by a connected to the output of the inverter diode D1 and a grounded capacitor C dc as a low-pass filter, which form of the high-frequency AC voltage U ac a smoothed DC voltage U dc .

Der der ersten Lampe LA1 zugeführte Gleichstrom Idc1 berechnet sich dann wie folgt: I dc1 = U dc R dc1 + R arc1 wobei Rarc1 der Widerstand der Gasentladungslampe LA1 ist. Der der zweiten Lampe LA2 zugeführte Gleichstrom ergibt sich analog. Dabei werden die beiden Widerstände Rdc1 und Rdc2 so ausgelegt, daß der zusätzliche Gleichstrom in etwa der Hälfte des nominalen 1 %-Stromes bei 25°C bis 35°C entspricht.The first lamp LA1 supplied direct current I dc1 is then calculated as follows: I dc 1 = U dc R dc 1 + R arc 1 where R arc1 is the resistance of the gas discharge lamp LA1. The direct current supplied to the second lamp LA2 results analogously. The two resistors R dc1 and R dc2 are designed so that the additional direct current in about half of the nominal 1% current at 25 ° C corresponds to 35 ° C.

Das Gewinnen der Gleichspannung Udc aus der Wechselspannung Uac des Wechselrichters hat den weiteren Vorteil, daß nach Abschalten des Wechselrichters auch der den Lampen LA1 und LA2 zugeführte Gleichstrom deaktiviert wird, so daß beide Lampen LA1, LA2 sicher ausgeschaltet werden. Allerdings bestünde auch die Möglichkeit, eine von dem Wechselrichter separate Gleichspannungsquelle zu verwenden. Der den Lampen LA1, LA2 zugeführte Gleichstrom verhindert darüber hinaus auch das Auftreten von sogenannten laufenden Schichten.The recovery of the DC voltage U dc from the AC voltage U ac of the inverter has the further advantage that after switching off the inverter and the lamps LA1 and LA2 supplied DC power is deactivated, so that both lamps LA1, LA2 are turned off safely. However, it would also be possible to use a separate DC voltage source from the inverter. The direct current supplied to the lamps LA1, LA2 also prevents the occurrence of so-called running layers.

Die Symmetrierwirkung des Transformators Lbal funktioniert allerdings nur bis zu einem gewissen Dimmpegel. Bei Helligkeitswerten unterhalb dieses Dimmpegels ist der Lampenstrom derart gering, daß kapazitive Ströme entstehen können, die größer als die Lampenströme selbst sind. Diese kapazitiven Ströme können beispielsweise dadurch entstehen, daß die Zuleitungen der Lampen unsymmetrisch verlegt sind, wodurch - wie bei der zweiten Lampe LA2 schematisch dargestellt - zusätzliche Verdrahtungskapazitäten Cpar und damit kapazitive Ströme Ipar auftreten. Sind diese kapazitiven Ströme Ipar größer als die Lampenströme, reagiert der Symmetriertransformator Lbal in einer Weise, daß die Unsymmetrie verstärkt wird. Der Lampe LA1, welche die zusätzliche Verdrahtungskapazität nicht aufweist, wird dann ein zusätzlicher Wirkstrom Iarc1 zugeführt, der sich auf folgende Weise abschätzen läßt: I arc1 ≈ I arc2 2+ I par 2 However, the balancing effect of the transformer L bal only works up to a certain dimming level. At brightness values below this dimming level, the lamp current is so low that capacitive currents that are greater than the lamp currents themselves can arise. These capacitive currents can arise, for example, due to the fact that the supply lines of the lamps are laid asymmetrically, as a result of which additional wiring capacities C par and thus capacitive currents I par occur, as shown schematically in the second lamp LA2. If these capacitive currents I par are greater than the lamp currents, the balancing transformer L bal reacts in such a way that the asymmetry is increased. The lamp LA1, which does not have the additional wiring capacity, is then supplied with an additional active current I arc1 , which can be estimated in the following way: I arc 1 ≈ I arc 2 2 + I par 2

Um dem entgegenzutreten, soll die Symmetrierwirkung des Transformators Lbal für geringe Lampenströme reduziert werden, ohne daß hiervon die Gleichstromquellen beeinflußt werden. Dies wird dadurch erreicht, daß die beiden ausgangsseitigen Anschlüsse der Wicklungen des Symmetriertransformators Lbal durch eine frequenzabhängige Impedanz, die im vorliegenden Beispiel aus der Serienschaltung eines Widerstands Rbal und eines Kondensators Cbal besteht, miteinander verbunden werden. Diese Verbindung erlaubt einen gewissen Ausgleich von kleinen Asymmetrien. Die Reduktion der Symmetrierwirkung wirkt sich jedoch nur auf die Wechselstromkomponente der Lampenspannung aus, also nur auf jenen Teil, der bei kleinen Dimmpegeln für die kapazitiven Ströme verantwortlich ist.To counter this, the balancing effect of the transformer L bal is to be reduced for low lamp currents, without this affecting the DC sources. This is achieved in that the two output-side terminals of the windings of the balancing transformer L bal by a frequency-dependent impedance, which consists in the present example of the series connection of a resistor R bal and a capacitor C bal , are interconnected. This connection allows a certain balance of small asymmetries. However, the reduction of the balancing effect has an effect only on the AC component of the lamp voltage, ie only on that part which is responsible for the capacitive currents at small dimming levels.

Die Wirkung der erfindungsgemäßen Schaltung ist schematisch in Figur 2 dargestellt. Der hier dargestellte Graph zeigt dabei die an den Lampen LA1 und LA2 anliegende und sich zeitlich verändernde Lampenspannung Uarc1 bzw. Uarc2. Zwar wird beiden Lampen nach wie vor die gleiche Wechselspannung Uac1 bzw. Uac2 zugeführt, da sie nun allerdings gleichstrommäßig entkoppelt sind, können sie eine unterschiedliche Gleichspannungskomponente Udc1 bzw. Udc2 annehmen. Als Folge davon kann jede Lampe exakt die Spannung annehmen, die sie für den vorgegebenen Helligkeitswert bzw. Lampenstrom ausbilden müßte. Dadurch ist die Möglichkeit gegeben, beide Lampen durch einen einzigen Wechselrichter anzusteuern und sie dennoch beide bei der gewünschten Helligkeit zu betreiben.The effect of the circuit according to the invention is shown schematically in FIG. The graph shown here shows the voltage applied to the lamps LA1 and LA2 and time-varying lamp voltage U arc1 and U arc2 . Although the same AC voltage U ac1 or U ac2 is still supplied to both lamps, since they are now DC-decoupled, they can assume a different DC voltage component U dc1 or U dc2 . As a result, each lamp can exactly take on the voltage that it would have to form for the given brightness value or lamp current. This provides the ability to drive both lamps through a single inverter and still operate both at the desired brightness.

Da darüber hinaus die Gefahr des zufälligen Verlöschens einer der beiden Lampen LA1 bzw. LA2 nicht mehr gegeben ist, ist es nicht mehr notwendig. wie bei der in Figur 4 dargestellten Schaltungsanordnung für jede Lampe eine eigene Erfassungsschaltung vorzusehen. Statt dessen kann - wie in Figur 1 dargestellt - lediglich eine einzige Erfassungsschaltung 2, beispielsweise in Form eines Tiefpasses, verwendet werden, welche die über einen am Fußpunkt der Halbbrückenschaltung angeordneten Meßwiderstand RSENS abfallende Spannung erfaßt und dementsprechend einen Istwert VIST erzeugt. Dieser Istwert entspricht nun der Summe der Wirkleistungen beider Gasentladungslampen LA1 und LA2. Der von der Erfassungsschaltung 2 erzeugte Istwert VIST wird der Steuerschaltung 1 zugeführt, welche nach einem Vergleich des Istwerts Vist mit einem der gewünschten Helligkeit entsprechenden Sollwert VSOLL die beiden Schalter S1 und S2 des Wechselrichters ansteuert.Moreover, since the risk of accidental wiping of one of the two lamps LA1 and LA2 is no longer given, it is no longer necessary. as in the case of the circuit arrangement shown in FIG. 4, to provide a separate detection circuit for each lamp. Instead, as shown in FIG. 1, only a single detection circuit 2 may be used, for example in the form of a low-pass filter, which detects the voltage drop across a measuring resistor R SENS arranged at the base of the half-bridge circuit and accordingly generates an actual value V IST . This actual value now corresponds to the sum of the active powers of both gas discharge lamps LA1 and LA2. The actual value produced by the detection circuit 2 V IS is supplied to the control circuit 1, according to a comparison of the actual value V is the two switches controls with a desired brightness corresponding the target value V TARGET S1 and S2 of the inverter.

Ein weiterer Vorteil der erfindungsgemäßen Schaltungsanordnung besteht auch darin, daß diese ohne Schwierigkeiten auf mehr als zwei Lampen erweitert werden kann. Dies ist in Figur 3 dargestellt, welche die Erweiterung des Systems auf drei Gasentladungslampen LA1, LA2 und LA3 darstellt. Die Erweiterung besteht lediglich darin, daß nunmehr mehrere Symmetriertransformatoren Lbal12 und Lbal23 verwendet werden, welche jeweils die Ströme von zwei Lampen LA1 und LA2 bzw. LA2 und LA3 symmetrieren. Wiederum sind die ausgangsseitigen Anschlüsse der Symmetriertransformatoren Lbal12 und Lbal23 über die zuvor beschriebene Serienschaltung aus einem Widerstand Rbal12 bzw. Rbal23 und einer Kapazität Cbal12 bzw. Cbal23 miteinander verbunden um eine Entkopplung der Gleichstromkomponenten zu bewirken. Eine Erweiterung des Systems auf n Gasentladungslampen besteht dann lediglich darin, daß (n-1) Symmetriertransformatoren verwendet werden, welche jeweils die Ströme von zwei Lampen symmetrieren.Another advantage of the circuit arrangement according to the invention is also that it can be extended without difficulty to more than two lamps. This is illustrated in Figure 3, which illustrates the extension of the system to three gas discharge lamps LA1, LA2 and LA3. The extension consists merely in that now several balancers L bal12 and L bal23 are used, which respectively symmetrize the currents of two lamps LA1 and LA2 or LA2 and LA3. Again, to cause the output-side terminals of the balancing transformers bal12 L and L bal23 over the previously described series combination of a resistor R or R bal12 bal23 and a capacitance C bal12 or C bal23 connected to a decoupling of the DC components. An extension of the system to n gas discharge lamps is then only that (n-1) balancing transformers are used, which each symmetrize the currents of two lamps.

Insbesondere bei der Erweiterung auf mehr als zwei Gasentladungslampen zeigt sich der Vorteil der erfindungsgemäßen Schaltungsanordnung, da nach wie vor die Verwendung einer einzigen Erfassungsschaltung 2 ausreichend ist, wodurch eine deutliche Vereinfachung der Schaltung erzielt wird.Especially when expanding to more than two gas discharge lamps, the Advantage of the circuit arrangement according to the invention, since still the use a single detection circuit 2 is sufficient, whereby a significant Simplification of the circuit is achieved.

Claims (9)

  1. Circuitry arrangement for the operation of n gas discharge lamps (LA1, LA2, LA3), n being a whole number greater than 1, with a single inverter (S1, S2), fed with d.c. voltage (VBUS), for the generation of an a.c. voltage (Uac) alterable in its frequency, which is delivered to a load circuit arranged at the output of the inverter (S1, S2), the load circuit having the following:
    a series resonant circuit of an inductance (La) and a capacitance (Cr), and
    n gas discharge lamps (LA1, LA2, LA3) connected to the common node point between the inductance (La) and the capacitance (Cr), which lamps are connected in parallel to one another,
    characterized in that,
    the load circuit further has for each gas discharge lamp (LA1, LA2, LA3) a d.c. current supply line via which there is delivered to each gas discharge lamp (LA1, LA2, LA3) a d.c. current, and
    in that the circuitry arrangement has a detection circuit which detects the sum of the effective powers of the gas discharge lamps (LA1, LA2, LA3) arranged in the load circuit and generates a corresponding actual value (VIST),
    and a control circuit which controls the inverter on the basis of a comparison between a desired value (VSOLL) and the actual value (VIST) generated by means of the detection circuit.
  2. Circuitry arrangement according to claim 1,
    characterized in that,
    the circuitry arrangement has (n-1) balancing transformers (Lbal, Lbal12, Lbal23) for the balancing of the current in each case of two gas discharge lamps (LA1, LA2, LA3),
  3. Circuitry arrangement according to claim 1 or 2,
    characterized in that,
    each of the d.c. supply lines is in each case connected between the output side terminal of the corresponding winding of the balancing transformer (Lbal, Lbal12, Lbal23) and the corresponding gas discharge lamp (LA1, LA2, LA3)
  4. Circuitry arrangement according to any of claims 1 to 3,
    characterized in that,
    the d.c. supply lines have each a resistance (Rdc1, Rdc2, Rdc3) connected in series and in that at their input side terminal there is applied a common supply voltage (Udc), the resistance values of these resistances (Rdc1, Rdc2, Rdc3) being the same.
  5. Circuitry arrangement according to any of claims 1 to 4,
    characterized in that,
    the common supply voltage (Udc) is formed by means of a diode (D1) connected to the output of the inverter.
  6. Circuitry arrangement according to any of claims 1 to 5,
    characterized in that,
    a low pass filter (Cdc) is arranged between the diode (D1) and the d.c. current lines.
  7. Circuitry arrangement according to any of claims 1 to 6,
    characterized in that,
    the output terminals of the windings of a balancing transformer (Lbal, Lbal12, Lbal23) are connected with one another in each case by means of a series circuit of a capacitor (Cbal, Cbal12, Cbal23) and a resistance (Rbal, Rbal12, Rbal23).
  8. Circuitry arrangement according to any of claims 1 to 7,
    characterized in that,
    the inverter is formed by means of two switches (S1, S2) arranged in a half-bridge arrangement.
  9. Circuitry arrangement according to any of claims 1 to 8,
    characterized in that,
    the detection circuit detects the voltage dropped via a resistance (RSENS) arranged at the base point of the half-bridge.
EP01982352A 2000-10-09 2001-09-25 Circuit arrangement for operating several gas discharge lamps Expired - Lifetime EP1330946B1 (en)

Applications Claiming Priority (3)

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DE10049842A DE10049842A1 (en) 2000-10-09 2000-10-09 Operating circuit for gas discharge lamps, has additional DC supply line for each gas discharge lamp for preventing unwanted lamp extinction
DE10049842 2000-10-09
PCT/EP2001/011073 WO2002032196A1 (en) 2000-10-09 2001-09-25 Circuit arrangement for operating several gas discharge lamps

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EP1330946B1 true EP1330946B1 (en) 2005-03-16

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EP (1) EP1330946B1 (en)
AT (1) ATE291342T1 (en)
AU (2) AU2002213959B2 (en)
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US6765354B2 (en) 2004-07-20
AU2002213959B2 (en) 2005-12-22
ATE291342T1 (en) 2005-04-15
AU1395902A (en) 2002-04-22
EP1330946A1 (en) 2003-07-30
WO2002032196A1 (en) 2002-04-18
DE10049842A1 (en) 2002-04-11
US20030214252A1 (en) 2003-11-20
DE50105646D1 (en) 2005-04-21

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