EP1915036A1 - Pre-switching device for operating at least one low pressure discharge lamp - Google Patents

Pre-switching device for operating at least one low pressure discharge lamp Download PDF

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Publication number
EP1915036A1
EP1915036A1 EP08150534A EP08150534A EP1915036A1 EP 1915036 A1 EP1915036 A1 EP 1915036A1 EP 08150534 A EP08150534 A EP 08150534A EP 08150534 A EP08150534 A EP 08150534A EP 1915036 A1 EP1915036 A1 EP 1915036A1
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EP
European Patent Office
Prior art keywords
pressure discharge
low
transformer
lamp
winding
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EP08150534A
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German (de)
French (fr)
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EP1915036B1 (en
Inventor
Juergen Klier
Rene Twardzik
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Osram GmbH
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Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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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
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
    • H05B41/2825—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a bridge converter in the final stage
    • H05B41/2827—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a bridge converter in the final stage using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations

Definitions

  • the invention relates to a ballast for operating at least one low-pressure discharge lamp according to the preamble of patent claims 1 or 2.
  • ballast for operating two parallel-connected low-pressure discharge lamps is disclosed on a half-bridge inverter.
  • the ballast has a transformer with two similar windings, which are each connected in one of the two lamp current branches. This transformer works as a differential current transformer. If one of the two lamps ignites earlier than the other, the ignition of the other lamp is supported by means of the transformer.
  • ballasts for operating a plurality of low-pressure discharge lamps
  • the problem often arises that the lamps shine differently brightly in dimming operation. If the lamps are arranged in different, parallel-connected current branches, this problem can be caused by different currents in the current branches. On the other hand, this problem also occurs in lamps, which - as in a series connection of two lamps - are arranged in the same branch of current.
  • the ballast comprises an inverter provided with a downstream load circuit designed as a resonant circuit into which the lamps are connected, those lamps which are directly connected to the resonant circuit components often shine brighter than the downstream lamps.
  • This variant of the invention is particularly well suited for the operation of three parallel-connected low-pressure discharge lamps. It is characterized by a particularly simple wiring of the lamp.
  • the two transformers act as a differential current transformer due to the opposite arrangement of their first and second windings.
  • the special turn ratio of 2: 1 between the first and second windings in both transformers ensures that all three current branches are symmetrical, since the second windings of the two transformers are traversed by the partial currents of two current branches.
  • it is ensured by the special arrangement of the windings of both transformers that on the one hand, the currents in the three current branches are balanced and on the other hand, the losses due to parasitic Capacities are compensated in each individual branch or in each individual lamp. Therefore, all three lamps shine brightly even in strong dimming.
  • the ballast has electrical connections for a single low-pressure discharge lamp or electrical connections for a plurality of low-pressure discharge lamps connected in series.
  • this ballast has a transformer with two windings of the same number of turns, the first winding - connected with low-pressure discharge lamp or connected low-pressure discharge lamps - the low-pressure discharge lamp or the series connection of the low-pressure discharge lamps immediately upstream, and the second winding of the low-pressure discharge lamp or the series circuit of Low-pressure discharge lamps is connected immediately downstream, so that the windings of the transformer are traversed in opposite directions from the lamp current.
  • this transformer With the help of this transformer and the arrangement of its windings according to the invention it is ensured that the two ends of the operated on the ballast low-pressure discharge lamp appear bright even with strong dimming, or that shine in a series circuit of several low-pressure discharge lamps, the series-connected low-pressure discharge lamps bright.
  • the windings of the transformer force a balancing of the current in the supply lines, immediately before and after the low-pressure discharge lamp, or immediately before and after the series connection of the low-pressure discharge lamps.
  • the losses due to parasitic capacitances in the lamps are compensated by means of the transformer.
  • the ballast according to the invention is advantageously designed as an inverter with a downstream load circuit, wherein the electrical connections for the low-pressure discharge lamps or the power branches are arranged with the electrical connections for at least one low-pressure charge lamp in the load circuit to operate the lamps with a high-frequency alternating current can.
  • the operation of the lamps with a high frequency alternating current improved the light output and allows easy brightness control of the lamps by changing the AC frequency.
  • a half-bridge inverter is used as the inverter, whose downstream load circuit is designed as a series resonant circuit.
  • the design of the load circuit as a series resonant circuit enables easy ignition of the low-pressure discharge lamps by means of the resonance peaking method.
  • the ballast has a half-bridge inverter which consists essentially of the transistors T1, T2 and a (not shown) driving device for the transistors T1, T2 and the half-bridge capacitor C2.
  • the half-bridge inverter T1, T2 is supplied at its voltage inputs with a DC voltage U, which is generated in a known manner by filtering and rectification of the AC line voltage.
  • the filter and rectifier circuit of the ballast are therefore not shown in the figures and will not be further described here.
  • the inductance L1 is connected at the center tap M1 between the transistors T1, T2 of the half-bridge inverter.
  • the inductor L1 To the inductor L1 is the first terminal of the capacitor C 1 is connected, while the second terminal of the capacitor C1 is connected to the ground potential.
  • the inductance L1 and the capacitor C1 form a series resonant circuit.
  • the first terminal of the resonance capacitor C1 is connected via a parallel connection of a plurality of low-pressure discharge lamps or a series connection of low-pressure discharge lamps or a combination of both with the first terminal of the half-bridge capacitor C2.
  • the second terminal of the half-bridge capacitor C2 is at ground potential.
  • Half of the supply voltage U of the half-bridge inverter is applied to the half-bridge capacitor C2.
  • the transistors T1, T2 are switched by means of the drive device in a known manner alternately with a frequency of more than 20 kHz, so that the center tap M1 is alternately connected to the ground potential and the positive potential U. Between the center tap M1 and the second terminal of the half-bridge capacitor C2 therefore flows a correspondingly high-frequency alternating current, with which the low-pressure discharge lamps are operated.
  • the ballast for operating low-pressure discharge lamps in particular of fluorescent lamps, which are each provided with two heatable electrode coils for generating a gas discharge. Each electrode coil has two electrical connections, via which the electrode coil can be acted upon by means of a (not shown) heater H in a known manner with a heating current to enable a gentle lamp operation.
  • the ballast is used to operate three parallel-connected low-pressure discharge lamps, in particular fluorescent lamps L10, L11, L12.
  • FIG. 1 the circuit arrangement of this ballast is shown schematically.
  • this ballast has two transformers Tr10, Tr11, each with two windings 10a, 10b, 11a, 11b.
  • the turns ratio of the windings 10a, 10b of the first transformer Tr10 is 2: 1.
  • the turns ratio of the windings 11a, 11b of the second transformer Tr11 is 2: 1.
  • the winding 10a of the transformer Tr10 is connected in the first current path, in series with the fluorescent lamp L10.
  • the second winding 10b of the transformer Tr10 is connected both in the second current path, in series with the fluorescent lamp L11, as well as in the third current path, in series with the fluorescent lamp L12.
  • the winding 10a is therefore traversed by the discharge current of the fluorescent lamp L10, while the winding 10b is traversed by the discharge currents of the fluorescent lamps L11 and L12.
  • the two windings 10a, 10b are wound in opposite directions, so that they are traversed in opposite directions by the discharge current of the lamps.
  • the first winding 11a of the transformer Tr11 is connected in the third current path, in series with the fluorescent lamp L 12, while the second winding 11b is connected both in the first current path, in series with the fluorescent lamp L10, and in the second current path, in series with Fluorescent lamp L11, is switched.
  • the winding 11a is therefore traversed by the discharge current of the fluorescent lamp L12, while the winding 11b is traversed by the discharge currents of the fluorescent lamps L10 and L11.
  • the windings 11a, 11b are arranged in opposite directions, so that they are traversed in opposite directions by the discharge currents or lamp currents.
  • the first transformer Tr10 is the fluorescent lamps L10 to L12 immediately upstream, while the second transformer Tr11 is the fluorescent lamps L10 to L12 immediately downstream. All three current paths are thus formed completely symmetrical.
  • the two transformers Tr10, Tr11 each act as differential current transformers and ensure that regardless of the dimming level, all three lamps light up the same brightly.
  • the ballast is used to operate two series-connected low-pressure discharge lamps, in particular fluorescent lamps L70, L71.
  • FIG. 2 is the circuitry of this Ballast schematically shown.
  • the ballast also has a transformer Tr7 with two windings 7a, 7b of the same number of turns. Both windings 7a, 7b are connected in series to the series connection of the lamps L70, L71, so that they are traversed in opposite directions by the lamp current.
  • the first winding 8a is connected immediately before the series connection of the lamps L70, L71 and the second winding 7b immediately behind the series connection of the lamps L70, L71 in the load circuit of the half-bridge inverter T1, T2.
  • the transformer Tr7 works as a differential current transformer. It compensates for losses due to parasitic capacitances.
  • the ballast for operating a low-pressure discharge lamp, in particular fluorescent lamp L8.
  • FIG. 3 the circuit arrangement of this ballast is shown schematically.
  • the discharge path of the lamp L8 is connected between the first terminal of the resonance capacitor C1 and at the first terminal of the half-bridge capacitor C2 in the load circuit of the half-bridge inverter.
  • the ballast also has a transformer Tr8 with two windings 8a, 8b of the same number of turns. Both windings 8a, 8b are connected in series with the discharge path of the lamp L8, so that they are traversed in opposite directions by the lamp current.
  • the first winding 8a is connected immediately before the discharge path of the lamp L8 and the second winding 8b is connected directly behind the discharge path of the lamp L8 into the load circuit of the half-bridge inverter T1, T2.
  • the transformer Tr8 works as a differential current transformer. It compensates for the losses due to parasitic capacitances and ensures that both ends of the L8 fluorescent lamp shine brightly even in the case of strong dimming.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)

Abstract

The ballast includes three branch circuits connected in parallel and to lamps (L10 - L12) and a pair of oppositely wound transformers (Tr10,Tr11). The windings (10a,10b) of the transformer (Tr10) are connected in series with the lamp (L10) and the lamps (L11,L12) respectively. The windings (11a,11b) of the transformer (Tr11) are in series with lamp (L12) and the lamps (L10,L11) respectively.

Description

Die Erfindung betrifft ein Vorschaltgerät zum Betrieb von mindestens einer Niederdruckentladungslampe gemäß dem Oberbegriff der Patentansprüche 1 oder 2.The invention relates to a ballast for operating at least one low-pressure discharge lamp according to the preamble of patent claims 1 or 2.

I. Stand der Technik I. State of the art

In der Patentschrift US 4,392,085 ist ein Vorschaltgerät zum Betrieb von zwei parallel geschalteten Niederdruckentladungslampen an einem Halbbrückenwechselrichter offenbart. Das Vorschaltgerät weist einen Transformator mit zwei gleichartigen Wicklungen auf, die jeweils in einen der beiden Lampenstromzweige geschaltet sind. Dieser Transformator arbeitet als Differenzstromtransformator. Zündet eine der beiden Lampen früher als die andere, so wird mit Hilfe des Transformators die Zündung der anderen Lampe unterstützt.In the patent US 4,392,085 a ballast for operating two parallel-connected low-pressure discharge lamps is disclosed on a half-bridge inverter. The ballast has a transformer with two similar windings, which are each connected in one of the two lamp current branches. This transformer works as a differential current transformer. If one of the two lamps ignites earlier than the other, the ignition of the other lamp is supported by means of the transformer.

II. Darstellung der Erfindung II. Presentation of the invention

Bei Vorschaltgeräten zum Betrieb von mehreren Niederdruckentladungslampen, tritt häufig das Problem auf, dass beim Dimmbetrieb die Lampen unterschiedlich hell leuchten. Sind die Lampen in unterschiedlichen, parallel geschalteten Stromzweigen angeordnet, so kann dieses Problem durch unterschiedliche Ströme in den Stromzweigen verursacht sein. Andererseits tritt dieses Problem aber auch bei Lampen auf, die - wie bei einer Serienschaltung von zwei Lampen - in demselben Stromzweig angeordnet sind. Insbesondere, wenn das Vorschaltgerät einen Wechselrichter aufweist, der mit einem nachgeschalteten, als Resonanzkreis ausgeführten Lastkreis versehen ist, in den die Lampen geschaltet sind, leuchten diejenigen Lampen, die unmittelbar mit den Resonanzkreisbauteilen verbunden sind, häufig heller als die nachgeschalteten Lampen. Zusätzlich kann beobachtet werden, dass bei dem Betrieb von nur einer Niederdruckentladungslampe in jedem Stromzweig die beiden Enden der Lampe unterschiedlich hell leuchten. Diese Helligkeitsunterschiede werden um so deutlicher, je stärker die Lampen gedimmt werden. Aus den vorgenannten Gründen muss bei herkömmlichen Betriebsgeräten bzw. Vorschaltgeräten, insbesondere für die Serienschaltung von mehreren Niederdruckentladungslampen die untere Dimmstufe bzw. Helligkeitsstufe auf ungefähr 10% der maximalen Helligkeit begrenzt werden. Die vorgenannten Probleme werden durch parasitäre Kapazitäten zwischen der Lampe bzw. den Lampenleitungen und der Leuchte sowie auch durch parasitäre Kapazitäten innerhalb der Heizkreise verursacht.In the case of ballasts for operating a plurality of low-pressure discharge lamps, the problem often arises that the lamps shine differently brightly in dimming operation. If the lamps are arranged in different, parallel-connected current branches, this problem can be caused by different currents in the current branches. On the other hand, this problem also occurs in lamps, which - as in a series connection of two lamps - are arranged in the same branch of current. In particular, when the ballast comprises an inverter provided with a downstream load circuit designed as a resonant circuit into which the lamps are connected, those lamps which are directly connected to the resonant circuit components often shine brighter than the downstream lamps. In addition, it can be observed that in the operation of only one low-pressure discharge lamp in each branch of the current, the two ends of the lamp shine differently bright. These brightness differences become more pronounced the more the lamps are dimmed. For the aforementioned reasons, in conventional control gear or ballasts, in particular for the series connection of several low-pressure discharge lamps, the lower dimming level or brightness level must be limited to approximately 10% of the maximum brightness become. The above-mentioned problems are caused by parasitic capacitances between the lamp or lamp leads and the luminaire as well as parasitic capacitances within the heating circuits.

Es ist die Aufgabe der Erfindung, ein Vorschaltgerät bereitzustellen, bei dem die obengenannten Probleme nicht mehr auftreten.It is the object of the invention to provide a ballast in which the above problems no longer occur.

Diese Aufgabe wird durch ein Vorschaltgerät mit den Merkmalen der Patentansprüche 1 oder 2 gelöst. Besonders vorteilhafte Ausführungen der Erfindung sind in den abhängigen Patentansprüchen offenbart.This object is achieved by a ballast with the features of claims 1 or 2. Particularly advantageous embodiments of the invention are disclosed in the dependent claims.

Für Niederdruckentladungslampen, die in drei parallel geschalteten Stromzweigen angeordnet sind, wird die Aufgabe durch ein Vorschaltgerät mit den Merkmalen des Patentanspruchs 1 gelöst. Für Niederdruckentladungslampen, die in demselben Stromzweig angeordnet sind, das heißt, für eine Serienschaltung von mehreren Niederdruckentladungslampen oder für den Betrieb einer einzigen Niederdruckentladungslampe, wird die Aufgabe der Erfindung durch ein Vorschaltgerät mit den Merkmalen des Patentanspruchs 2 gelöst.For low-pressure discharge lamps, which are arranged in three parallel-connected current branches, the object is achieved by a ballast having the features of patent claim 1. For low-pressure discharge lamps, which are arranged in the same current branch, that is, for a series connection of a plurality of low-pressure discharge lamps or for the operation of a single low-pressure discharge lamp, the object of the invention by a ballast with the features of claim 2 is achieved.

Gemäß einer ersten Variante der Erfindung besitzt das Vorschaltgerät drei parallel geschaltete Stromzweige, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe geschaltet sind. Außerdem weist dieses Vorschaltgerät folgende weiteren Merkmale auf:

  • einen Transformator zur Symmetrierung der Lampenströme, wobei der Transformator eine erste und eine zweite Wicklung besitzt, und wobei die erste Wicklung doppelt so viele Windungen wie die zweite Wicklung besitzt,
  • einen zweiten Transformator zur Symmetrierung der Lampenströme, wobei der zweite Transformator eine erste und eine zweite Wicklung besitzt und die erste Wicklung doppelt so viele Windungen wie die zweite Wicklung besitzt, wobei
  • die Wicklungen der Transformatoren derart angeordnet sind, dass bei angeschlossenen Niederdruckentladungslampen, die Lampenströme zuerst durch die Wicklungen eines der beiden Transformatoren, dann durch die Niederdruckentladungslampen und anschließend erst durch die Wicklungen des anderen Transformators fließen, wobei
  • die erste Wicklung des ersten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von dem Lampenstrom der in den ersten Stromzweig geschalteten Niederdruckentladungslampe bzw. Niederdruckentladungslampen durchflossen wird, wobei
  • die zweite Wicklung des ersten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von den Lampenströmen der in den zweiten und dritten Stromzweig geschalteten Niederdruckentladungslampen durchflossen wird, und wobei die beiden Wicklungen des ersten Transformators gegensinnig gewickelt sind, wobei
  • die erste Wicklung des zweiten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von dem Lampenstrom der in den dritten Stromzweig geschalteten Niederdruckentladungslampe bzw. Niederdruckentladungslampen durchflossen wird, und wobei
  • die zweite Wicklung des zweiten Transformators derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen von den Lampenströmen der in den ersten und zweiten Stromzweig geschalteten Niederdruckentladungslampen durchflossen wird, wobei die beiden Wicklungen des zweiten Transformators gegensinnig gewickelt sind.
According to a first variant of the invention, the ballast has three parallel-connected current branches, in each of which electrical connections for at least one low-pressure discharge lamp are connected. In addition, this ballast has the following additional features:
  • a transformer for balancing the lamp currents, wherein the transformer has a first and a second winding, and wherein the first winding has twice as many turns as the second winding,
  • a second transformer for balancing the lamp currents, wherein the second transformer has a first and a second winding and the first winding has twice as many turns as the second winding, wherein
  • the windings of the transformers are arranged such that when connected low-pressure discharge lamps, the lamp currents first through the windings of one of the two transformers, then through the low-pressure discharge lamps and then flow through the windings of the other transformer, wherein
  • the first winding of the first transformer is arranged in such a way that, when the low-pressure discharge lamps are connected, the lamp current of the low-pressure discharge lamp or low-pressure discharge lamps connected in the first current branch flows through
  • the second winding of the first transformer is arranged such that it is traversed by the lamp currents of the connected in the second and third branch low-pressure discharge lamps in connected low-pressure discharge lamps, and wherein the two windings of the first transformer are wound in opposite directions
  • the first winding of the second transformer is arranged in such a way that, when the low-pressure discharge lamps are connected, it flows through the lamp current of the low-pressure discharge lamp or low-pressure discharge lamps connected in the third current branch, and
  • the second winding of the second transformer is arranged in such a way that, when the low-pressure discharge lamps are connected, the lamp currents of the low-pressure discharge lamps connected in the first and second current branches flow, the two windings of the second transformer being wound in opposite directions.

Diese Variante der Erfindung ist besonders gut zum Betrieb von drei parallel geschalteten Niederdruckentladungslampen geeignet. Sie zeichnet sich durch eine besonders einfache Verdrahtung der Leuchte aus. Die beiden Transformatoren wirken aufgrund der gegensinnigen Anordnung ihrer ersten und zweiten Wicklungen jeweils wie ein Differenzstromtransformator. Durch das spezielle Windungsverhältnis von 2:1 zwischen der ersten und zweiten Wicklung bei beiden Transformatoren ist gewährleistet, dass alle drei Stromzweige symmetrisch ausgebildet sind, da die zweiten Wicklungen der beiden Transformatoren von den Teilströmen zweier Stromzweige durchflossen werden. Außerdem ist durch die spezielle Anordnung der Wicklungen beider Transformatoren sichergestellt, dass einerseits die Ströme in den drei Stromzweigen Symmetriert werden und andererseits auch die Verluste durch parasitäre Kapazitäten in jedem einzelnen Stromzweig bzw. in jeder einzelnen Lampe kompensiert werden. Daher leuchten alle drei Lampen selbst bei starker Dimmung gleichermaßen hell.This variant of the invention is particularly well suited for the operation of three parallel-connected low-pressure discharge lamps. It is characterized by a particularly simple wiring of the lamp. The two transformers act as a differential current transformer due to the opposite arrangement of their first and second windings. The special turn ratio of 2: 1 between the first and second windings in both transformers ensures that all three current branches are symmetrical, since the second windings of the two transformers are traversed by the partial currents of two current branches. In addition, it is ensured by the special arrangement of the windings of both transformers that on the one hand, the currents in the three current branches are balanced and on the other hand, the losses due to parasitic Capacities are compensated in each individual branch or in each individual lamp. Therefore, all three lamps shine brightly even in strong dimming.

Gemäß einer anderen Variante der Erfindung besitzt das Vorschaltgerät elektrische Anschlüsse für eine einzige Niederdruckenetladungslampe oder elektrische Anschlüsse für mehrere in Serie geschaltete Niederdruckentladungslampen. Außerdem weist dieses Vorschaltgerät einen Transformator mit zwei Wicklungen gleicher Windungszahl auf, wobei die erste Wicklung - bei angeschlossener Niederdruckentladungslampe bzw. bei angeschlossenen Niederdruckentladungslampen - der Niederdruckentladungslampe bzw. der Serienschaltung der Niederdruckentladungslampen unmittelbar vorgeschaltet ist, und die zweite Wicklung der Niederdruckentladungslampe bzw. der Serienschaltung der Niederdruckentladungslampen unmittelbar nachgeschaltet ist, so dass die Wicklungen des Transformators gegensinnig vom Lampenstrom durchflossen werden.According to another variant of the invention, the ballast has electrical connections for a single low-pressure discharge lamp or electrical connections for a plurality of low-pressure discharge lamps connected in series. In addition, this ballast has a transformer with two windings of the same number of turns, the first winding - connected with low-pressure discharge lamp or connected low-pressure discharge lamps - the low-pressure discharge lamp or the series connection of the low-pressure discharge lamps immediately upstream, and the second winding of the low-pressure discharge lamp or the series circuit of Low-pressure discharge lamps is connected immediately downstream, so that the windings of the transformer are traversed in opposite directions from the lamp current.

Mit Hilfe dieses Transformators und der erfindungsgemäßen Anordnung seiner Wicklungen wird gewährleistet, dass die beiden Enden der an dem Vorschaltgerät betriebenen Niederdruckentladungslampe auch bei starker Dimmung gleich hell erscheinen, bzw. dass bei einer Serienschaltung von mehreren Niederdruckentladungslampen, die in Serie geschalteten Niederdruckentladungslampen gleich hell leuchten. Die Wicklungen des Transformators erzwingen eine Symmetrierung des Stroms in den Zuleitungen, unmittelbar vor und hinter der Niederdruckentladungslampe, bzw. unmittelbar vor und hinter der Serienschaltung der Niederdruckentladungslampen. Die Verluste durch parasitäre Kapazitäten in den Lampen werden mittels des Transformators kompensiert.With the help of this transformer and the arrangement of its windings according to the invention it is ensured that the two ends of the operated on the ballast low-pressure discharge lamp appear bright even with strong dimming, or that shine in a series circuit of several low-pressure discharge lamps, the series-connected low-pressure discharge lamps bright. The windings of the transformer force a balancing of the current in the supply lines, immediately before and after the low-pressure discharge lamp, or immediately before and after the series connection of the low-pressure discharge lamps. The losses due to parasitic capacitances in the lamps are compensated by means of the transformer.

Das erfindungsgemäße Vorschaltgerät ist vorteilhafterweise als Wechselrichter mit einem nachgeschalteten Lastkreis ausgebildet ist, wobei die elektrischen Anschlüsse für die Niederdruckentladungslampen bzw. die Stromzweige mit den elektrischen Anschlüssen für mindestens eine Niederdruckladungslampe in dem Lastkreis angeordnet sind, um die Lampen mit einem hochfrequenten Wechselstrom betreiben zu können. Der Betrieb der Lampen mit einem hochfrequenten Wechselstrom verbessert die Lichtausbeute und ermöglicht eine einfache Helligkeitssteuerung der Lampen durch Ändern der Wechselstromfrequenz.The ballast according to the invention is advantageously designed as an inverter with a downstream load circuit, wherein the electrical connections for the low-pressure discharge lamps or the power branches are arranged with the electrical connections for at least one low-pressure charge lamp in the load circuit to operate the lamps with a high-frequency alternating current can. The operation of the lamps with a high frequency alternating current improved the light output and allows easy brightness control of the lamps by changing the AC frequency.

Gemäß der bevorzugten Ausführungsbeispiele der Erfindung wird als Wechselrichter insbesondere ein Halbbrückenwechselrichter verwendet, dessen nachgeschalteter Lastkreis als Serienresonanzkreis ausgebildet ist. Die Ausbildung des Lastkreises als Serienresonanzkreises ermöglicht eine einfache Zündung der Niederdruckentladungslampen mittels der Methode der Resonanzüberhöhung.According to the preferred embodiments of the invention, in particular a half-bridge inverter is used as the inverter, whose downstream load circuit is designed as a series resonant circuit. The design of the load circuit as a series resonant circuit enables easy ignition of the low-pressure discharge lamps by means of the resonance peaking method.

III. Beschreibung der bevorzugten Ausführungsbeispiele III. Description of the preferred embodiments

Nachstehend wird die Erfindung anhand mehrerer bevorzugter Ausführungsbeispiele näher erläutert. Es zeigen:

Figur 1
Die Schaltungsanordnung eines Vorschaltgerätes gemäß dem ersten Ausführungsbeispiel der Erfindung in schematischer Darstellung
Figur 2
Die Schaltungsanordnung eines Vorschaltgerätes gemäß dem zweiten Ausführungsbeispiel der Erfindung in schematischer Darstellung
Figur 3
Die Schaltungsanordnung eines Vorschaltgerätes gemäß dem dritten Ausführungsbeispiel der Erfindung in schematischer Darstellung
The invention will be explained in more detail with reference to several preferred embodiments. Show it:
FIG. 1
The circuit arrangement of a ballast according to the first embodiment of the invention in a schematic representation
FIG. 2
The circuit arrangement of a ballast according to the second embodiment of the invention in a schematic representation
FIG. 3
The circuit arrangement of a ballast according to the third embodiment of the invention in a schematic representation

In den Figuren wurden für identische Bauteile des Vorschaltgerätes bzw. der Schaltungsanordnung die gleichen Bezugszeichen gewählt. Bei allen Ausführungsbeispielen der Erfindung besitzt das Vorschaltgerät einen Halbbrückenwechselrichter, der im wesentlichen von den Transistoren T1, T2 und einer (nicht abgebildeten) Ansteuerungsvorrichtung für die Transistoren T1, T2 sowie aus dem Halbbrückenkondensator C2 besteht. Der Halbbrückenwechselrichter T1, T2 wird an seinen Spannungseingängen mit einer Gleichspannung U versorgt, die in bekannter Weise durch Filterung und Gleichrichtung aus der Netzwechselspannung generiert wird. Die Filter-und Gleichrichterschaltung des Vorschaltgerätes sind daher in den Figuren nicht dargestellt und sollen hier auch nicht weiter beschrieben werden. An den Mittenabgriff M1 zwischen den Transistoren T1, T2 des Halbbrückenwechselrichters ist die Induktivität L1 angeschlossen. An die Induktivität L1 ist der erste Anschluß des Kondensators C 1 angeschlossen, während der zweite Anschluß des Kondensators C1 mit dem Massepotential verbunden ist. Die Induktivität L1 und der Kondensator C1 bilden einen Serienresonanzkreis. Der erste Anschluß des Resonanzkondensators C1 ist über eine Parallelschaltung von mehreren Niederdruckentladungslampen oder eine Serienschaltung von Niederdruckentladungslampen oder eine Kombination von beiden mit dem ersten Anschluß des Halbbrückenkondensators C2 verbunden. Der zweite Anschluß des Halbbrückenkondensators C2 liegt auf Massepotential. An dem Halbbrückenkondensator C2 liegt die Hälfte der Versorgungsspannung U des Halbbrückenwechselrichters an. Die Transistoren T1, T2 werden mittels der Ansteuerungsvorrichtung in bekannter Weise alternierend mit einer Frequenz von mehr als 20 kHz geschaltet, so dass der Mittenabgriff M1 abwechselnd mit dem Massepotential und dem positiven Potential U verbunden ist. Zwischen dem Mittenabgriff M1 und dem zweiten Anschluß des Halbbrückenkondensators C2 fließt daher ein entsprechend hochfrequenter Wechselstrom, mit dem die Niederdruckentladungslampen betrieben werden. Bei allen Ausführungsbeispielen dient das Vorschaltgerät zum Betrieb von Niederdruckentladungslampen, insbesondere von Leuchtstofflampen, die mit jeweils mit zwei heizbaren Elektrodenwendeln zur Erzeugung einer Gasentladung versehen sind. Jede Elektrodenwendel besitzt zwei elektrische Anschlüsse, über die die Elektrodenwendel mittels einer (nicht abgebildeten) Heizvorrichtung H in bekannter Weise mit einem Heizstrom beaufschlagt werden kann, um einen schonenden Lampenbetrieb zu ermöglichen. In den Figuren sind die elektrischen Anschlüsse der Elektrodenwendeln bzw. der Niederdruckentladungslampen, die mit der Heizvorrichtung H verbunden sind, entsprechend mit dem Bezugszeichen H versehen. Da die Heizvorrichtung H bekannt ist und für die vorliegende Erfindung keine Rolle spielt, wird sie hier nicht weiter erläutert. So weit stimmen alle acht Ausführungsbeispiele überein.In the figures, the same reference numerals have been selected for identical components of the ballast or the circuit arrangement. In all embodiments of the invention, the ballast has a half-bridge inverter which consists essentially of the transistors T1, T2 and a (not shown) driving device for the transistors T1, T2 and the half-bridge capacitor C2. The half-bridge inverter T1, T2 is supplied at its voltage inputs with a DC voltage U, which is generated in a known manner by filtering and rectification of the AC line voltage. The filter and rectifier circuit of the ballast are therefore not shown in the figures and will not be further described here. At the center tap M1 between the transistors T1, T2 of the half-bridge inverter, the inductance L1 is connected. To the inductor L1 is the first terminal of the capacitor C 1 is connected, while the second terminal of the capacitor C1 is connected to the ground potential. The inductance L1 and the capacitor C1 form a series resonant circuit. The first terminal of the resonance capacitor C1 is connected via a parallel connection of a plurality of low-pressure discharge lamps or a series connection of low-pressure discharge lamps or a combination of both with the first terminal of the half-bridge capacitor C2. The second terminal of the half-bridge capacitor C2 is at ground potential. Half of the supply voltage U of the half-bridge inverter is applied to the half-bridge capacitor C2. The transistors T1, T2 are switched by means of the drive device in a known manner alternately with a frequency of more than 20 kHz, so that the center tap M1 is alternately connected to the ground potential and the positive potential U. Between the center tap M1 and the second terminal of the half-bridge capacitor C2 therefore flows a correspondingly high-frequency alternating current, with which the low-pressure discharge lamps are operated. In all embodiments, the ballast for operating low-pressure discharge lamps, in particular of fluorescent lamps, which are each provided with two heatable electrode coils for generating a gas discharge. Each electrode coil has two electrical connections, via which the electrode coil can be acted upon by means of a (not shown) heater H in a known manner with a heating current to enable a gentle lamp operation. In the figures, the electrical connections of the electrode filaments and the low-pressure discharge lamps, which are connected to the heater H, provided with the reference numeral H accordingly. Since the heater H is known and plays no role in the present invention, it will not be further explained here. So far agree all eight embodiments match.

Gemäß dem ersten Ausführungsbeispiel der Erfindung dient das Vorschaltgerät zum Betrieb von drei parallel geschalteten Niederdruckentladungslampen, insbesondere Leuchtstofflampen L10, L11, L12. In Figur 1 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. An den ersten Anschluß des Resonanzkondensators C1 und an den ersten Anschluß des Halbbrückenkondensators C2 sind drei parallel geschaltete Stromzweige angeschlossen, in die jeweils eine Niederdruckentladungslampe L10 bzw. L11 bzw. L12 geschaltet ist. Außerdem weist dieses Vorschaltgerät zwei Transformatoren Tr10, Tr11 mit jeweils zwei Wicklungen 10a, 10b, 11a, 11b auf. Das Windungsverhältnis der Wicklungen 10a, 10b des ersten Transformators Tr10 beträgt 2:1. Ebenso beträgt auch das Windungsverhältnis der Wicklungen 11a, 11b des zweiten Transformators Tr11 2:1. Die Wicklung 10a des Transformators Tr10 ist in den ersten Strompfad, in Serie zur Leuchtstofflampe L10 geschaltet. Die zweite Wicklung 10b des Transformators Tr10 ist sowohl in den zweiten Strompfad, in Serie zur Leuchtstofflampe L11, als auch in den dritten Strompfad, in Serie zur Leuchtstofflampe L12 geschaltet. Die Wicklung 10a wird daher von dem Entladungsstrom der Leuchtstofflampe L10 durchflossen, während die Wicklung 10b von den Entladungsströmen der Leuchtstofflampen L11 und L12 durchflossen wird. Die beiden Wicklungen 10a, 10b sind gegensinnig gewickelt, so dass sie gegensinnig vom Entladungsstrom der Lampen durchflossen werden. Analog dazu ist die erste Wicklung 11a des Transformators Tr11 in den dritten Strompfad, in Serie zur Leuchtstofflampe L 12 geschaltet, während die zweite Wicklung 11b sowohl in den ersten Strompfad, in Serie zur Leuchtstofflampe L10, als auch in den zweiten Strompfad, in Serie zur Leuchtstofflampe L11, geschaltet ist. Die Wicklung 11a wird daher von dem Entladungsstrom der Leuchtstofflampe L12 durchflossen, während die Wicklung 11b von den Entladungsströmen der Leuchtstofflampen L10 und L11 durchflossen wird. Die Wicklungen 11a, 11b sind gegensinnig angeordnet, so dass sie gegensinnig von den Entladungsströmen bzw. Lampenströmen durchflossen werden. Der erste Transformator Tr10 ist den Leuchtstofflampen L10 bis L12 unmittelbar vorgeschaltet, während der zweite Transformator Tr11 den Leuchtstofflampen L10 bis L12 unmittelbar nachgeschaltet ist. Alle drei Strompfade sind also vollkommen symmetrisch ausgebildet. Die beiden Transformatoren Tr10, Tr11 wirken jeweils als Differenzstromtransformatoren und gewährleisten, dass unabhängig von der Dimmstufe alle drei Lampen gleich hell leuchten.According to the first exemplary embodiment of the invention, the ballast is used to operate three parallel-connected low-pressure discharge lamps, in particular fluorescent lamps L10, L11, L12. In FIG. 1 the circuit arrangement of this ballast is shown schematically. To the first terminal of the resonance capacitor C1 and to the first terminal of the half-bridge capacitor C2 are three connected in parallel current branches, in each of which a low-pressure discharge lamp L10 or L11 or L12 is connected. In addition, this ballast has two transformers Tr10, Tr11, each with two windings 10a, 10b, 11a, 11b. The turns ratio of the windings 10a, 10b of the first transformer Tr10 is 2: 1. Likewise, the turns ratio of the windings 11a, 11b of the second transformer Tr11 is 2: 1. The winding 10a of the transformer Tr10 is connected in the first current path, in series with the fluorescent lamp L10. The second winding 10b of the transformer Tr10 is connected both in the second current path, in series with the fluorescent lamp L11, as well as in the third current path, in series with the fluorescent lamp L12. The winding 10a is therefore traversed by the discharge current of the fluorescent lamp L10, while the winding 10b is traversed by the discharge currents of the fluorescent lamps L11 and L12. The two windings 10a, 10b are wound in opposite directions, so that they are traversed in opposite directions by the discharge current of the lamps. Analogously, the first winding 11a of the transformer Tr11 is connected in the third current path, in series with the fluorescent lamp L 12, while the second winding 11b is connected both in the first current path, in series with the fluorescent lamp L10, and in the second current path, in series with Fluorescent lamp L11, is switched. The winding 11a is therefore traversed by the discharge current of the fluorescent lamp L12, while the winding 11b is traversed by the discharge currents of the fluorescent lamps L10 and L11. The windings 11a, 11b are arranged in opposite directions, so that they are traversed in opposite directions by the discharge currents or lamp currents. The first transformer Tr10 is the fluorescent lamps L10 to L12 immediately upstream, while the second transformer Tr11 is the fluorescent lamps L10 to L12 immediately downstream. All three current paths are thus formed completely symmetrical. The two transformers Tr10, Tr11 each act as differential current transformers and ensure that regardless of the dimming level, all three lamps light up the same brightly.

Gemäß dem zweiten Ausführungsbeispiel der Erfindung dient das Vorschaltgerät zum Betrieb von zwei in Serie geschalteten Niederdruckentladungslampen, insbesondere Leuchtstofflampen L70, L71. In Figur 2 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. An den ersten Anschluß des Resonanzkondensators C1 und an den ersten Anschluß des Halbbrückenkondensators C2 ist die Serienschaltung der beiden Leuchtstofflampen L70, L71 angeschlossen. Das Vorschaltgerät besitzt außerdem einen Transformator Tr7 mit zwei Wicklungen 7a, 7b gleicher Windungszahl. Beide Wicklungen 7a, 7b sind in Serie zu der Serienschaltung der Lampen L70, L71 geschaltet, so dass sie gegensinnig von dem Lampenstrom durchflossen werden. Die erste Wicklung 8a ist unmittelbar vor der Serienschaltung der Lampen L70, L71 und die zweite Wicklung 7b unmittelbar hinter der Serienschaltung der Lampen L70, L71 in den Lastkreis des Halbbrückenwechselrichters T1, T2 geschaltet. Der Transformator Tr7 arbeitet als Differenzstromtransformator. Er kompensiert die Verluste durch parasitäre Kapazitäten.According to the second embodiment of the invention, the ballast is used to operate two series-connected low-pressure discharge lamps, in particular fluorescent lamps L70, L71. In FIG. 2 is the circuitry of this Ballast schematically shown. To the first terminal of the resonant capacitor C1 and to the first terminal of the half-bridge capacitor C2, the series connection of the two fluorescent lamps L70, L71 is connected. The ballast also has a transformer Tr7 with two windings 7a, 7b of the same number of turns. Both windings 7a, 7b are connected in series to the series connection of the lamps L70, L71, so that they are traversed in opposite directions by the lamp current. The first winding 8a is connected immediately before the series connection of the lamps L70, L71 and the second winding 7b immediately behind the series connection of the lamps L70, L71 in the load circuit of the half-bridge inverter T1, T2. The transformer Tr7 works as a differential current transformer. It compensates for losses due to parasitic capacitances.

Gemäß dem dritten Ausführungsbeispiel der Erfindung dient das Vorschaltgerät zum Betrieb einer Niederdruckentladungslampe, insbesondere Leuchtstofflampe L8. In Figur 3 ist die Schaltungsanordnung dieses Vorschaltgerätes schematisch abgebildet. Die Entladungsstrecke der Lampe L8 ist zwischen dem ersten Anschluß des Resonanzkondensators C1 und an dem ersten Anschluß des Halbbrückenkondensators C2 in den Lastkreis des Halbbrückenwechselrichters geschaltet. Das Vorschaltgerät besitzt außerdem einen Transformator Tr8 mit zwei Wicklungen 8a, 8b gleicher Windungszahl. Beide Wicklungen 8a, 8b sind in Serie zu der Entladungsstrecke der Lampe L8 geschaltet, so dass sie gegensinnig von dem Lampenstrom durchflossen werden. Die erste Wicklung 8a ist unmittelbar vor der Entladungsstrecke der Lampe L8 und die zweite Wicklung 8b unmittelbar hinter der Entladungsstrecke der Lampe L8 in den Lastkreis des Halbbrückenwechselrichters T1, T2 geschaltet. Der Transformator Tr8 arbeitet als Differenzstromtransformator. Er kompensiert die Verluste durch parasitäre Kapazitäten und die gewährleistet dadurch, dass beide Enden der Leuchtstofflampe L8 auch bei starker Dimmung gleich hell leuchten.According to the third embodiment of the invention, the ballast for operating a low-pressure discharge lamp, in particular fluorescent lamp L8. In FIG. 3 the circuit arrangement of this ballast is shown schematically. The discharge path of the lamp L8 is connected between the first terminal of the resonance capacitor C1 and at the first terminal of the half-bridge capacitor C2 in the load circuit of the half-bridge inverter. The ballast also has a transformer Tr8 with two windings 8a, 8b of the same number of turns. Both windings 8a, 8b are connected in series with the discharge path of the lamp L8, so that they are traversed in opposite directions by the lamp current. The first winding 8a is connected immediately before the discharge path of the lamp L8 and the second winding 8b is connected directly behind the discharge path of the lamp L8 into the load circuit of the half-bridge inverter T1, T2. The transformer Tr8 works as a differential current transformer. It compensates for the losses due to parasitic capacitances and ensures that both ends of the L8 fluorescent lamp shine brightly even in the case of strong dimming.

Claims (2)

Vorschaltgerät zum Betrieb von mehreren Niederdruckentladungslampen, wobei das Vorschaltgerät drei parallel geschaltete Stromzweige besitzt, in die jeweils elektrische Anschlüsse für mindestens eine Niederdruckentladungslampe (L10, L11, L12) geschaltet sind,
dadurch gekennzeichnet, dass - das Vorschaltgerät einen Transformator (Tr10) zur Symmetrierung der Lampenströme aufweist, - der Transformator (Tr10) eine erste (10a) und eine zweite Wicklung (10b) besitzt, wobei die erste Wicklung (10a) doppelt so viele Windungen wie die zweite Wicklung (10b) besitzt, - das Vorschaltgerät einen zweiten Transformator (Tr11) zur Symmetrierung der Lampenströme aufweist, wobei der zweite Transformator (Tr11) eine erste (11a) und eine zweite Wicklung (11b) besitzt und die erste Wicklung (11a) doppelt so viele Windungen wie die zweite Wicklung (11b) besitzt, - die Wicklungen (10a, 10b, 11a, 11b) der Transformatoren (Tr10, Tr11) derart angeordnet sind, dass bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12), die Lampenströme zuerst durch die Wicklungen (10a, 10b bzw. 11a, 11b) eines der beiden Transformatoren (Tr10 bzw. Tr11), dann durch die Niederdruckentladungslampen (L10, L11, L12) und anschließend erst durch die Wicklungen (11a, 11b bzw. 10a, 10b) des anderen Transformators (Tr11 bzw. Tr10) fließen, - die erste Wicklung (10a) des ersten Transformators (Tr10) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12) von dem Lampenstrom der in den ersten Stromzweig geschalteten Niederdruckentladungslampe (L10) bzw. Niederdruckentladungslampen durchflossen wird, - die zweite Wicklung (10b) des ersten Transformators (Tr10) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L 10, L 11, L 12) von den Lampenströmen der in den zweiten und dritten Stromzweig geschalteten Niederdruckentladungslampen (L11, L12) durchflossen wird, wobei die beiden Wicklungen (10a, 10b) des ersten Transformators (Tr10) gegensinnig gewickelt sind, - die erste Wicklung (11a) des zweiten Transformators (Tr11) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L10, L11, L12) von dem Lampenstrom der in den dritten Stromzweig geschalteten Niederdruckentladungslampe (L12) bzw. Niederdruckentladungslampen durchflossen wird, - die zweite Wicklung (11b) des zweiten Transformators (Tr11) derart angeordnet ist, dass sie bei angeschlossenen Niederdruckentladungslampen (L 10, L 11, L 12) von den Lampenströmen der in den ersten und zweiten Stromzweig geschalteten Niederdruckentladungslampen (L10, L11) durchflossen wird, wobei die beiden Wicklungen (11a, 11b) des zweiten Transformators (Tr11) gegensinnig gewickelt sind. Ballast for operating a plurality of low-pressure discharge lamps, wherein the ballast has three parallel-connected current branches, in each of which electrical connections for at least one low-pressure discharge lamp (L10, L11, L12) are connected,
characterized in that - The ballast has a transformer (Tr10) for balancing the lamp currents, the transformer (Tr10) has a first (10a) and a second winding (10b), the first winding (10a) having twice as many windings as the second winding (10b), - The ballast comprises a second transformer (Tr11) for balancing the lamp currents, wherein the second transformer (Tr11) has a first (11a) and a second winding (11b) and the first winding (11a) twice as many windings as the second winding (11b) possesses - The windings (10a, 10b, 11a, 11b) of the transformers (Tr10, Tr11) are arranged such that when connected low-pressure discharge lamps (L10, L11, L12), the lamp currents first through the windings (10a, 10b and 11a, 11b ) of one of the two transformers (Tr10 or Tr11), then through the low-pressure discharge lamps (L10, L11, L12) and then only through the windings (11a, 11b or 10a, 10b) of the other transformer (Tr11 or Tr10) flow, the first winding (10a) of the first transformer (Tr10) is arranged in such a way that, when the low-pressure discharge lamps (L10, L11, L12) are connected, the lamp current of the low-pressure discharge lamp (L10) or low-pressure discharge lamps connected in the first current branch flows through, - The second winding (10b) of the first transformer (Tr10) is arranged such that it is connected to low-pressure discharge lamps (L 10, L 11, L 12) flows through the lamp currents of the second and third branched low-pressure discharge lamps (L11, L12), wherein the two windings (10a, 10b) of the first transformer (Tr10) are wound in opposite directions, the first winding (11a) of the second transformer (Tr11) is arranged in such a way that, when the low-pressure discharge lamps (L10, L11, L12) are connected, the lamp current of the low-pressure discharge lamp (L12) or low-pressure discharge lamps connected in the third branch current flows through, - The second winding (11b) of the second transformer (Tr11) is arranged such that when the low-pressure discharge lamps (L 10, L 11, L 12) flowed through by the lamp currents of the connected in the first and second branch current low-pressure discharge lamps (L10, L11) is, wherein the two windings (11a, 11b) of the second transformer (Tr11) are wound in opposite directions. Vorschaltgerät zum Betrieb von einer oder mehreren in Serie geschalteten Niederdruckentladungslampen, wobei das Vorschaltgerät einen Transformator (Tr8; Tr7) mit zwei Wicklungen (8a, 8b; 7a, 7b) gleicher Windungszahl aufweist, und wobei die erste Wicklung (8a; 7a) der Niederdruckentladungslampe (L8) bzw. der Serienschaltung der Niederdruckentladungslampen (L70, L71) unmittelbar vorgeschaltet ist, und die zweite Wicklung (8b; 7b) der Niederdruckentladungslampe (L8) bzw. der Serienschaltung der Niederdruckentladungslampen (L70, L71) unmittelbar nachgeschaltet ist, so dass die Wicklungen des Transformators (Tr8; Tr7) bei angeschlossener Niederdruckentladungslampe (L8) bzw. bei angeschlossenen Niederdruckentladungslampen (L70, L71) gegensinnig vom Lampenstrom durchflossen werden.A ballast for operating one or more series-connected low-pressure discharge lamps, the ballast having a transformer (Tr8; Tr7) with two windings (8a, 8b; 7a, 7b) of the same number of turns, and wherein the first winding (8a; 7a) of the low-pressure discharge lamp (L8) or the series circuit of the low-pressure discharge lamps (L70, L71) is connected immediately upstream, and the second winding (8b, 7b) of the low-pressure discharge lamp (L8) or the series connection of the low-pressure discharge lamps (L70, L71) is connected immediately downstream, so that the Windings of the transformer (Tr8; Tr7) with the low-pressure discharge lamp (L8) connected or with low-pressure discharge lamps connected (L70, L71) are flown in opposite directions from the lamp current.
EP08150534A 2001-07-23 2002-05-22 Pre-switching device for operating at least one low pressure discharge lamp Expired - Lifetime EP1915036B1 (en)

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EP1286572A2 (en) 2003-02-26
EP1286572B1 (en) 2008-10-29
ATE413086T1 (en) 2008-11-15
DE50214247D1 (en) 2010-04-08
DE50212951D1 (en) 2008-12-11
EP1915036B1 (en) 2010-02-24
CA2394409A1 (en) 2003-01-23
DE10134966A1 (en) 2003-02-06
ATE459232T1 (en) 2010-03-15
EP1286572A3 (en) 2005-01-19
US6717371B2 (en) 2004-04-06
US20030015974A1 (en) 2003-01-23

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