EP0279073A2 - Circuit arrangement for the high-frequency operation of fluorescent lamps having pre-heating electrodes - Google Patents

Circuit arrangement for the high-frequency operation of fluorescent lamps having pre-heating electrodes Download PDF

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Publication number
EP0279073A2
EP0279073A2 EP87119168A EP87119168A EP0279073A2 EP 0279073 A2 EP0279073 A2 EP 0279073A2 EP 87119168 A EP87119168 A EP 87119168A EP 87119168 A EP87119168 A EP 87119168A EP 0279073 A2 EP0279073 A2 EP 0279073A2
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EP
European Patent Office
Prior art keywords
lamp
current
frequency
arrangement according
electrodes
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EP87119168A
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German (de)
French (fr)
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EP0279073A3 (en
Inventor
Jürg NIGG
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Individual
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Individual
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R33/00—Coupling devices specially adapted for supporting apparatus and having one part acting as a holder providing support and electrical connection via a counterpart which is structurally associated with the apparatus, e.g. lamp holders; Separate parts thereof
    • H01R33/05—Two-pole devices
    • H01R33/06—Two-pole devices with two current-carrying pins, blades or analogous contacts, having their axes parallel to each other
    • H01R33/08—Two-pole devices with two current-carrying pins, blades or analogous contacts, having their axes parallel to each other for supporting tubular fluorescent lamp
    • H01R33/0809—Two-pole devices with two current-carrying pins, blades or analogous contacts, having their axes parallel to each other for supporting tubular fluorescent lamp having contacts on one side only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V19/00—Fastening of light sources or lamp holders
    • F21V19/0075—Fastening of light sources or lamp holders of tubular light sources, e.g. ring-shaped fluorescent light sources
    • F21V19/0095—Fastening of light sources or lamp holders of tubular light sources, e.g. ring-shaped fluorescent light sources of U-shaped tubular light sources, e.g. compact fluorescent tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R33/00—Coupling devices specially adapted for supporting apparatus and having one part acting as a holder providing support and electrical connection via a counterpart which is structurally associated with the apparatus, e.g. lamp holders; Separate parts thereof
    • H01R33/94—Holders formed as intermediate parts for linking a counter-part to a coupling part
    • H01R33/942—Holders formed as intermediate parts for linking a counter-part to a coupling part for tubular fluorescent lamps
    • 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
    • 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
    • H05B41/295—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 and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps

Definitions

  • the invention relates to a circuit arrangement for the high-frequency operation of fluorescent lamps with electrodes to be preheated.
  • Another advantage of higher operating frequencies is that the lower limit of the ambient temperature at which the lamp can still be operated reliably is lower than at a lower operating frequency, for example at 50 Hz. This is for the use of fluorescent lamps in cold rooms and outdoors essential. This advantage is also offset by the greater tendency to cold start at higher frequencies, even when used of special lamps for low temperatures.
  • the invention seeks to remedy this.
  • the invention as characterized in claim 1, solves the problem of creating a circuit arrangement for the high-frequency operation of fluorescent lamps with preheated electrodes, with which the tendency to cold starts can be avoided without impairing the luminous efficacy and operability at low ambient temperatures.
  • claims 2 to 9 embodiments of the invention are given.
  • the circuit of a high-frequency ballast for a fluorescent lamp 1 with electrodes 2 and 3 to be preheated is shown, which is designed for connection to an AC network (220 V).
  • the basic structure of this ballast consists of a rectifier 5 with alternating current connections 6 and 7 for the network and a smoothing capacitor 8 for the rectified alternating voltage which feeds a high-frequency inverter 10.
  • the inverter 10 supplies at two connections 11 and 12 the high-frequency combustion current for the lamp 1, which is in series with the self-induction required for its operation coil 13 is; it contains a current path 15, 16, 17 with connections 18 and 19, which is connected in series with the electrode coils (electrodes 2) instead of the starter, for example glow starter, which is usual when operating at mains frequency.
  • the coil 13 has a magnetic core (ferrite) with an air gap.
  • the basic principle of the inverter 10 is a "half-bridge current feedback inverter" with a transistor 22 for the half-waves in one direction and a transistor 23 for the half-waves in the other direction of the high-frequency current. It works according to this principle with current feedback.
  • a current transformer 27 with a magnetic core (ferrite) is used for this. The core and the number of turns of the primary winding 24 are dimensioned such that the core is magnetically saturated during part of each high-frequency half-wave.
  • the current transformer 27 has two secondary windings 25 and 26, each of which is connected to a resistor 28 or 29 in the control circuit (base-emitter circuit) of one of the transistors 22 and 23. The windings 25 and 26 are connected so that the control currents are in phase opposition.
  • Inverters of this principle require a surge to start up. Such is generated when the inverter 10 is switched on by the circuit elements 32, 33 and 34.
  • the function of these and the other circuit elements can be seen from the following description of the mode of operation of the inverter 10. For example, data of the circuit elements are given in parentheses.
  • the capacitor 33 (100 nF) is charged via the resistor 32 (470 kohm) and, when the breakdown voltage of the zener diode 34 (30-36 V) is exceeded, partially discharged by a current surge which flows via the base emitter Route of Transistor 23 flows and ends when the reference voltage of the Zener diode 34 is undershot.
  • This current surge produces one of the operational states of the inverter 10, in which one of the transistors 22 and 23 is conductive and the other is non-conductive.
  • the inverter 10 can swing.
  • the mode of operation of the inverter 10 is first described, regardless of whether its load current is the discharge current or the preheating current of the lamp, and only then does the process of preheating the electrodes 2 and 3 and burning the lamp 1 be discussed.
  • the current charging the capacitor 37 flowing through 13, 24, 23 and 35, generates, as it rises, a control current in the secondary winding 26 which keeps the transistor 23 conductive after the end of the current surge triggered to oscillate.
  • this control current decreases.
  • the transistor 23 blocks and interrupts the charging current and thus the primary current of the current converter 27.
  • capacitor 38 causes the current flowing through primary winding 24 in either direction to be maintained for a short time by different charging voltages of capacitors 37 and 38 (3.3 nF) , so that the other transistor 22 or 23 only becomes conductive after this time has elapsed. This prevents both transistors 22 and 23 from conducting simultaneously as a result of different response times, as a result of which the DC supply voltage of the inverter 10, which is connected to the capacitor 8, is short-circuited and the transistors are destroyed.
  • the difference in the charging voltages across the capacitors 37 and 38 is due to this that the capacitor 37 has a much larger capacitance than the capacitor 38, and that the lamp 1, the coil 13 and the primary winding 24 are in its charge or discharge circuit, while the capacitor 38 has a much smaller capacitance through the small resistor 35 and the collector-emitter path of transistor 23, the resistance of which is low in the conductive state, is charged and discharged via the collector-emitter path of transistor 22, the resistance of which is small in the conductive state, and the likewise low resistance 40 is discharged.
  • the time constant of the capacitor 38 and resistor 39 (220 kiloohms) is much larger than the inverter half-period.
  • the diodes 42 and 43 promote the ignition process, in which - as described below - the ignition voltage is generated at the coil 13, one end of which is connected directly to the lamp electrode 3.
  • the ignition current flows from the other end of the coil through the primary winding 24 and, depending on its direction, through the diode 42 and the capacitor 37 or through the diode 43, the capacitor 8 and the capacitor 37 to the other electrode 2.
  • the diodes 42 and 43 protect the transistors Reverse voltages that also occur when the primary current is interrupted in current transformer 27.
  • the diode 45 prevents the inverter 10 from being triggered again in the vibrating state via the circuit elements 32, 33, 34.
  • the frequency generated by the inverter 10 (without the lamp 1, 2, 3 and without the current path 15, 16 17) is essentially determined by the saturation behavior of the current transformer 27.
  • the inverter 10 also swings without the lamp 1 and the coil 13 when on a resistor (e.g. 1170 Ohm) is connected to it, with a frequency that is higher (50 kHz) than the frequency when the lamp 1 is operated.
  • this frequency is lower when the lamp electrodes 2 and 3 are preheated ( approx. 25 kHz) than when the lamp 1 is on (approx. 35 kHz), so that the cold start tendency of the lamp 1 during the preheating of the electrodes 2 and 3 is eliminated by the lower frequency, and when the lamp burns, the greater light output of the higher frequency comes into its own.
  • the series connection of the capacitor 15 (3300 pF), the resistor 16 (220 ohm) and the SIDAC 17 in the heating circuit of the electrodes 2 and 3 (130 V) is provided, whose impedance (without the SIDAC 17) is essentially determined by the capacitance of the capacitor 15, which is significantly smaller than that of the capacitor 37.
  • the breakdown voltage of the SIDAC 17 is higher than the operating voltage of the lamp 1 at higher frequency (35 kHz).
  • the capacitance of the capacitor 15 and the inductance of the coil 13 are dimensioned such that an appropriate preheating current flows through the electrodes 2 and 3 at the lower frequency (25 kHz), i.e.
  • the series circuit 15, 16 , 17 is de-energized because the operating voltage of the lamp 1 is less than the breakdown voltage of the SIDAC 17.
  • a high-frequency current flows through 37, 15, 16, 17 and 13, the frequency of which, under the action of the capacitor 15 and the coil 13, is lower (25 kHz) than the frequency (50 kHz) with which the inverter 10 would vibrate without these circuit elements.
  • the high-frequency current consists of successive half-waves, each of which increases very steeply when the breakdown voltage of the SIDAC 17 is reached. These very sudden current increases induce 13 voltage pulses on the coil, the voltage of which leads to the ignition of the lamp 1 as soon as the electrodes 2 and 3 are preheated.
  • the lamp 1 is then ignited, the voltage across the series circuit 15, 16, 17 drops to the operating voltage of the lamp 1, and thus the voltage across the SIDAC 17 falls below its breakdown voltage.
  • the series circuit 15, 16, 17 is de-energized. Now there is no longer the capacitance of the capacitor 15 but the much smaller capacitance (50 to 100 pF), which the SIDAC 17 represents in the blocking state, in series with the self-induction of the coil 13, because in the series connection of the capacitances of the capacitor 15 and the SIDAC 17 is not considered as the much larger one. Parallel to the capacity of the SIDAC 17 and lamp 1 is the capacity of the lines connected to them. The total capacitance is considerably smaller than that of the capacitor 15. Therefore, the inverter 10 now vibrates at the higher frequency (35 kHz), and the higher luminous efficiency is achieved at the higher frequency.
  • each lamp can also be fed in parallel, with each lamp being assigned a coil 13 and a heating current path 15, 16, 17.
  • an interference protection filter for the harmonics of the inverter frequency for example a so-called “boost converter”, can be connected in front of the inverter 10 or the rectifier 5.
  • the inverter 10 can be installed together with the rectifier 5, 8 (and, if desired, a noise protection filter) in an intermediate piece which has a base corresponding to the incandescent lamp base, with the connections 6 and 7 to be received by an incandescent lamp holder, and one the fluorescent lamp 1 has an interchangeable socket with contacts for the connections 11, 12, 18 and 19.

Abstract

An intermediate piece connected both to the supply and lamp sides is mechanically compatible with both. An adaptor or ballast device mechanically and electrically connects at least one lamp to a supply in this way. At least connection points comprising connection base and/or connection holder are provided for different holders and bases respectively.

Description

Die Erfindung bezieht sich auf eine Schaltungsanordnung für den Hochfrequenzbetrieb von Leuchtstofflampen mit vor­zuheizenden Elektroden.The invention relates to a circuit arrangement for the high-frequency operation of fluorescent lamps with electrodes to be preheated.

Es ist bekannt, dass die Lichtausbeute einer Leuchtstoff­lampe mit steigender Betriebsfrequenz zunimmt. Je höher die Frequenz ist, umso mehr neigt aber die Leuchtstoff­lampe dazu, kalt, d.h. bei noch nicht oder nicht ausrei­chend vorgeheizten Elektroden zu zünden. Durch solche Kaltstarts wird die Lebensdauer der Lampe erheblich herab­gesetzt.It is known that the luminous efficiency of a fluorescent lamp increases with an increasing operating frequency. The higher the frequency, the more the fluorescent lamp tends to be cold, i.e. to ignite if the electrodes have not been preheated or are not sufficiently preheated. Such cold starts significantly reduce the life of the lamp.

Ein weiterer Vorteil höherer Betriebsfrequenzen besteht darin, dass die untere Grenze der Umgebungstemperatur, bei der die Lampe noch zuverlässig beytrieben werden kann, niedriger liegt als bei einer tieferen Betriebsfrequenz, z.B. bei 50 Hz. Das ist für die Verwendung von Leuchtstoff­lampen in Kühlräumen und im Freien wesentlich. Auch diesem Vorteil steht die bei höheren Frequenzen stärkere Kalt­startneigung als Nachteil gegenüber, auch bei Verwendung von speziallampen für tiefe Temperaturen.Another advantage of higher operating frequencies is that the lower limit of the ambient temperature at which the lamp can still be operated reliably is lower than at a lower operating frequency, for example at 50 Hz. This is for the use of fluorescent lamps in cold rooms and outdoors essential. This advantage is also offset by the greater tendency to cold start at higher frequencies, even when used of special lamps for low temperatures.

Hier will die Erfindung Abhilfe schaffen. Die Erfindung, wie sie im Patentanspruch 1 gekennzeichnet ist, löst die Aufgabe, eine Schaltungsanordnung für den Hochfrequenz­betrieb von Leuchtstofflampen mit vorzuheizenden Elektro­den zu schaffen, mit welcher die Neigung zu Kaltstarts ohne Beeinträchtigung der Lichtausbeute und der Betriebs­fähigkeit bei tiefen Umgebungstemperaturen vermieden wer­den kann. In den Patentansprüchen 2 bis 9 sind Ausführungs­möglichkeiten der Erfindung angegeben.The invention seeks to remedy this. The invention, as characterized in claim 1, solves the problem of creating a circuit arrangement for the high-frequency operation of fluorescent lamps with preheated electrodes, with which the tendency to cold starts can be avoided without impairing the luminous efficacy and operability at low ambient temperatures. In the claims 2 to 9 embodiments of the invention are given.

Die durch die Erfindung erreichten Vorteile sind im wesent­lichen darin zu sehen, dass alle Vorteile des Hochfre­quenzbetriebs ohne die die Lebensdauer verkürzende Kalt­startneigung erzielt werden.The advantages achieved by the invention are essentially to be seen in the fact that all the advantages of high-frequency operation are achieved without the cold start tendency which shortens the service life.

Im folgenden wird die Erfindung anhand lediglich einen Aus­führungsweg darstellender Zeichnung näher erläutert. Die einzige Figur zeigt das Schema einer erfindungsge­mässen Schaltungsanordnung für den Hochfrequenzbetrieb einer Leuchtstofflampe mit vorzuheizenden Elektroden.In the following, the invention is explained in more detail with reference to a drawing which shows only one embodiment. The single figure shows the diagram of a circuit arrangement according to the invention for the high-frequency operation of a fluorescent lamp with electrodes to be preheated.

In der Zeichnung ist die Schaltung eines Hochfrequenz-­Vorschaltgerätes für eine Leuchtstofflampe 1 mit vorzu­heizenden Elektroden 2 und 3 dargestellt, das zum An­schluss an ein Wechselstromnetz (220 V) ausgeführt ist. Dieses Vorschaltgerät besteht in seinem grundsätzlichen Aufbau aus einem Gleichrichter 5 mit Wechselstroman­schlüssen 6 und 7 für das Netz und einem Glättungskon­densator 8 für die gleichgerichtete Wechselspannung, die einen Wechselrichter 10 hoher Frequenz speist. Der Wech­selrichter 10 liefert an zwei Anschlüssen 11 und 12 den hochfrequenten Brennstrom für die Lampe 1, die in Reihe mit der für ihren Betrieb erforderlichen Selbstinduktions­ spule 13 liegt; er enthält einen Strompfad 15, 16, 17 mit Anschlüssen 18 und 19, der anstelle des beim Betrieb mit Netzfrequenz üblichen Starters, z.B. Glimmstarters, in Reihe mit den Elektrodenwendeln (Elektroden 2) geschal­tet ist. Die Spule 13 hat einen magnetischen Kern (Ferrit) mit Luftspalt.In the drawing, the circuit of a high-frequency ballast for a fluorescent lamp 1 with electrodes 2 and 3 to be preheated is shown, which is designed for connection to an AC network (220 V). The basic structure of this ballast consists of a rectifier 5 with alternating current connections 6 and 7 for the network and a smoothing capacitor 8 for the rectified alternating voltage which feeds a high-frequency inverter 10. The inverter 10 supplies at two connections 11 and 12 the high-frequency combustion current for the lamp 1, which is in series with the self-induction required for its operation coil 13 is; it contains a current path 15, 16, 17 with connections 18 and 19, which is connected in series with the electrode coils (electrodes 2) instead of the starter, for example glow starter, which is usual when operating at mains frequency. The coil 13 has a magnetic core (ferrite) with an air gap.

Der Wechselrichter 10 ist im Grundprinzip ein "Half-­Bridge Current-Feedback-Inverter" mit einem Transistor 22 für die Halbwellen der einen Richtung und einen Tran­sistor 23 für die Halbwellen der anderen Richtung ds Hochfrequenzstroms. Er arbeitet gemäss diesem Prinzip mit Stromrückkopplung. Dazu dient ein Stromwandler 27 mit einem magnetischen Kern (Ferrit). Der Kern und die Windungszahl der Primärwicklung 24 sind so bemessen, dass der Kern während eines Teiles jeder Hochfrequenzhalb­welle magnetisch gesättigt ist. Der Stromwandler 27 hat zwei Sekundärwicklungen 25 und 26, die je über einen Wider­stand 28 bzw. 29 im Steuerstromkreis (Basis-Emitter-Kreis) eines der Transistoren 22 und 23 liegen. Dabei sind die Wicklungen 25 und 26 so angeschlossen, dass die Steuer­ströme gegenphasig sind. Zum Anschwingen benötigen Wech­selrichter dieses Prinzips einen Stromstoss. Ein solcher wird beim Einschalten des Wechselrichters 10 durch die Schaltungselemente 32, 33 und 34 erzeugt. Die Funktion dieser und der weiteren Schaltungselemente ist aus der folgenden Beschreibung der Wirkungsweise des Wechselrich­ters 10 ersichtlich. Beispielsweise Daten der Schal­tungselemente sind in Klammern angegeben.The basic principle of the inverter 10 is a "half-bridge current feedback inverter" with a transistor 22 for the half-waves in one direction and a transistor 23 for the half-waves in the other direction of the high-frequency current. It works according to this principle with current feedback. A current transformer 27 with a magnetic core (ferrite) is used for this. The core and the number of turns of the primary winding 24 are dimensioned such that the core is magnetically saturated during part of each high-frequency half-wave. The current transformer 27 has two secondary windings 25 and 26, each of which is connected to a resistor 28 or 29 in the control circuit (base-emitter circuit) of one of the transistors 22 and 23. The windings 25 and 26 are connected so that the control currents are in phase opposition. Inverters of this principle require a surge to start up. Such is generated when the inverter 10 is switched on by the circuit elements 32, 33 and 34. The function of these and the other circuit elements can be seen from the following description of the mode of operation of the inverter 10. For example, data of the circuit elements are given in parentheses.

Nach dem Einschalten des Wechselrichters 10 wird der Kon­densator 33 (100 nF) über den Widerstand 32 (470 Koloohm) geladen und, beim Ueberschreiten der Durchbruchspannung der Zenerdiode 34 (30-36 V) durch einen Stromstoss teil­weise entladen, der über die Basis-Emitter-Strecke des Transistors 23 fliesst und endet, wenn die Referenz­spannung der Zenerdiode 34 unterschritten wird. Durch diesen Stromstoss wird einer der betriebsmässigen Zu­stände des Wechselrichters 10, in dem einer der Transi­storen 22 und 23 leitend und der andere nichtleitend ist, hergestellt. Der Wechselrichter 10 kann anschwingen.After the inverter 10 has been switched on, the capacitor 33 (100 nF) is charged via the resistor 32 (470 kohm) and, when the breakdown voltage of the zener diode 34 (30-36 V) is exceeded, partially discharged by a current surge which flows via the base emitter Route of Transistor 23 flows and ends when the reference voltage of the Zener diode 34 is undershot. This current surge produces one of the operational states of the inverter 10, in which one of the transistors 22 and 23 is conductive and the other is non-conductive. The inverter 10 can swing.

Bei leitendem Transistor 22 fliesst ein den Kondensator 37 (68 nF) ladenden Strom durch die an den Anschlüssen 11/12 und 18/19 angeschlossenen Lampe 1, die Primär­wicklung 24, die Spule 13 (5,5 mH), den Transistor 23 und den Widerstand 35 (3,9 Ohm). Bei brennender Lampe 1 fliesst dieser Strom nur zwischen den Anschlüssen 11 und 12, während des Vorheizens der Lampenelektroden 2 und 3 fliesst dieser Strom vom Anschluss 1 durch die Elektro­de 2 (Heizwendel) zum Anschluss 18, durch den Strom­pfad 15, 16, 17 zum Anschluss 19 und von diesem durch die Elektrode 3 zum Anschluss 12. Dies bleibt im folgen­den zunächst unbeachtet. Es wird zuerst die Wirkungsweise des Wechselrichters 10 unabhängig davon beschrieben, ob sein Laststrom der Entladungsstrom oder der Vorheizstrom der Lampe ist, und erst danach auf die Vorgänge beim Vor­heizen der Elektroden 2 und 3 und beim Brennen der Lampe 1 eingegangen. Der den Kondensator 37 ladende, durch 13, 24, 23 und 35 fliessende Strom erzeugt, während er an­steigt, in der Sekundärwicklung 26 einen Steuerstrom, der den Transistor 23 nach dem Ende des zum Anschwingen aus­gelösten Stromstosses leitend halt. Sobald der Primärstrom beginnt, den Magnetkern des Stromwandlers 27 zu sättigen, nimmt dieser Steuerstrom ab. Schliesslich sperrt der Transistor 23 und unterbricht den Ladestrom und damit den Primärstrom des Stromwandlers 27.When the transistor 22 is conducting, a current charging the capacitor 37 (68 nF) flows through the lamp 1 connected to the connections 11/12 and 18/19, the primary winding 24, the coil 13 (5.5 mH), the transistor 23 and the Resistor 35 (3.9 ohms). When the lamp 1 is lit, this current only flows between the connections 11 and 12, while the lamp electrodes 2 and 3 are preheated, this current flows from the connection 1 through the electrode 2 (heating coil) to the connection 18, through the current path 15, 16, 17 to the connection 19 and from this through the electrode 3 to the connection 12. This will initially be ignored in the following. The mode of operation of the inverter 10 is first described, regardless of whether its load current is the discharge current or the preheating current of the lamp, and only then does the process of preheating the electrodes 2 and 3 and burning the lamp 1 be discussed. The current charging the capacitor 37, flowing through 13, 24, 23 and 35, generates, as it rises, a control current in the secondary winding 26 which keeps the transistor 23 conductive after the end of the current surge triggered to oscillate. As soon as the primary current begins to saturate the magnetic core of the current transformer 27, this control current decreases. Finally, the transistor 23 blocks and interrupts the charging current and thus the primary current of the current converter 27.

Bei dieser Primärstromunterbrechung wird in der anderen Sekundärwicklung 25 ein Strom induziert, der durch die Basis-Emitter-Strecke des Transistors 22 fliesst, so dass dieser leitend wird. Nun fliesst ein den Kondensator 37 entladender Strom durch den Transistor 22, den Widerstand 40 (3,9 Ohm), die Primärwicklung 24, die Lampe 1 und die Spule 13. Der Anstieg des nun zum vorherigen Ladestrom entgegengesetzten Entladestromes in der Primärwicklung 24 induziert in der Sekundärwicklung 25 einen Strom, der dieselbe Richtung hat wie der Strom, der vorher in der­selben Sekundärwicklung 22 erzeugt wurde, als der Lade­strom abnahm. Also hält der nun in der Sekundärwicklung 25 induzierte und durch die Basis-Emitter-Strecke des Transistors 22 fliessende Steuerstrom den Transistor 22 leitend. Sobald der den Kondensator 37 über 22, 40, 24, 13 und 1 entladende Strom beginnt, der Kern des Strom­wandlers 27 zu sättigen, nimmt der ihn aufrecht erhal­tende, in der Sekundärwicklung 25 induzierte Steuerstrom ab. Schliesslich sperrt der Transistor 22. Dabei indu­ziert der Stromabfall in der Primärwicklung 24 einen Strom in der Sekundärwicklung 26, durch den der Transistor 23 leitend wird. Damit beginnt der beschriebene Zyklus von neuem.During this primary current interruption, a current is induced in the other secondary winding 25, which is caused by The base-emitter path of the transistor 22 flows so that it becomes conductive. Now a current discharging the capacitor 37 flows through the transistor 22, the resistor 40 (3.9 ohms), the primary winding 24, the lamp 1 and the coil 13. The increase in the discharge current now opposite to the previous charging current in the primary winding 24 induces in the secondary winding 25 has a current in the same direction as the current that was previously generated in the same secondary winding 22 when the charging current decreased. Thus, the control current now induced in the secondary winding 25 and flowing through the base-emitter path of the transistor 22 keeps the transistor 22 conductive. As soon as the current discharging the capacitor 37 via 22, 40, 24, 13 and 1 begins to saturate the core of the current transformer 27, the control current induced in the secondary winding 25 which maintains it decreases. Finally, the transistor 22 blocks. The current drop in the primary winding 24 induces a current in the secondary winding 26 through which the transistor 23 becomes conductive. The cycle described begins again.

Wenn der Transistor 23 oder 22 in den Sperrzustand über­geht, bewirkt der Kondensator 38, dass der durch die Pri­märwicklung 24 in der einen bzw. anderen Richtung flies­sende Strom noch kurze Zeit durch unterschiedliche Lade­spannungen der Kondensatoren 37 und 38 (3,3 nF) aufrecht­erhalten wird, so dass der andere Transistor 22 bzw. 23 erst nach Ablauf dieser Zeit leitend wird. Dadurch wird verhindert, dass beide Transistoren 22 und 23 infolge unterschiedlicher Ansprechzeiten gleichzeitig leiten, wo­durch die am Kondensator 8 liegende Gleichstromspeise­spannung des Inverters 10 kurzgeschlossen und die Tran­sistoren zerstört würden. Der Unterschied der Ladespan­nungen an den Kondensatoren 37 und 38 ist darauf zurück­ zuführen, dass der Kondensator 37 eine viel grössere Kapazität als der Kondensator 38 hat, und dass in seinem Lade- bzw. Entladestromkreis die Lampe 1, die Spule 13 und die Primärwicklung 24 liegt, während der Kondensator 38 viel kleinerer Kapazität über den kleinen Widerstand 35 und die Kollektor-Emitter-Strecke des Transistors 23, deren Widerstand im leitenden Zustand klein ist, gela­den und über die Kollektor-Emitter-Strecke des Transistors 22, deren Widerstand im leitenden Zustand klein ist, und den ebenfalls kleinen Widerstand 40 entladen wird. Die Zeitkonstante des Kondensators 38 und Widerstands 39 (220 Kiloohm) ist wesentlich grösser als die Wechsel­richterhalbperiode.When transistor 23 or 22 turns off, capacitor 38 causes the current flowing through primary winding 24 in either direction to be maintained for a short time by different charging voltages of capacitors 37 and 38 (3.3 nF) , so that the other transistor 22 or 23 only becomes conductive after this time has elapsed. This prevents both transistors 22 and 23 from conducting simultaneously as a result of different response times, as a result of which the DC supply voltage of the inverter 10, which is connected to the capacitor 8, is short-circuited and the transistors are destroyed. The difference in the charging voltages across the capacitors 37 and 38 is due to this that the capacitor 37 has a much larger capacitance than the capacitor 38, and that the lamp 1, the coil 13 and the primary winding 24 are in its charge or discharge circuit, while the capacitor 38 has a much smaller capacitance through the small resistor 35 and the collector-emitter path of transistor 23, the resistance of which is low in the conductive state, is charged and discharged via the collector-emitter path of transistor 22, the resistance of which is small in the conductive state, and the likewise low resistance 40 is discharged. The time constant of the capacitor 38 and resistor 39 (220 kiloohms) is much larger than the inverter half-period.

Die Dioden 42 und 43 fördern den Zündvorgang, bei dem - wie weiter unten beschrieben - die Zündspannung an der Spule 13 entsteht, deren eines Ende direkt mit der Lam­penelektrode 3 verbunden ist. Vom anderen Spulenende fliesst der Zündstrom durch die Primärwicklung 24 und je nach seiner Richtung durch die Diode 42 und den Kon­densator 37 oder durch die Diode 43, den Kondensator 8 und den Kondensator 37 zur anderen Elektrode 2. Die Dio­den 42 und 43 schützen die Transistoren vor Spannungen in Sperrichtung, die auch bei den Unterbrechungen des Primärstroms in Stromwandler 27 auftreten. Die Diode 45 verhindert, dass der Wechselrichter 10 im schwingenden Zustand nochmals über die Schaltungselemente 32, 33, 34 zum Anschwingen angestossen wird.The diodes 42 and 43 promote the ignition process, in which - as described below - the ignition voltage is generated at the coil 13, one end of which is connected directly to the lamp electrode 3. The ignition current flows from the other end of the coil through the primary winding 24 and, depending on its direction, through the diode 42 and the capacitor 37 or through the diode 43, the capacitor 8 and the capacitor 37 to the other electrode 2. The diodes 42 and 43 protect the transistors Reverse voltages that also occur when the primary current is interrupted in current transformer 27. The diode 45 prevents the inverter 10 from being triggered again in the vibrating state via the circuit elements 32, 33, 34.

Wie ersichtlich, ist die vom Wechselrichter 10 (ohne die Lampe 1, 2, 3 und ohne den Strompfad 15, 16 17) er­zeugte Frequenz wesentlich durch das Sättigungsverhalten des Stromwandlers 27 bestimmt. Der Wechselrichter 10 schwingt auch ohne die Lampe 1 und die Spule 13, wenn an deren Stelle ein Widerstand (z.B. 1170 Ohm) angeschlossen wird, mit einer Frequenz, die höher ist (50 kHz) als die Frequenz beim Betrieb der Lampe 1. Diese Frequenz ist, wie im folgenden erläutert, beim Vorheizen der Lampenelektro­den 2 und 3 tiefer (ca. 25 kHz) als bei brennender Lampe 1 (ca. 35 kHz), so dass die Kaltstartneigung der Lampe 1 während des Vorheizens der Elektroden 2 und 3 durch die niedrigere Frequenz behoben ist, und biem Brennen der Lam­pe die grössere Lichtausbeute der höreren Frequenz zur Geltung kommt.As can be seen, the frequency generated by the inverter 10 (without the lamp 1, 2, 3 and without the current path 15, 16 17) is essentially determined by the saturation behavior of the current transformer 27. The inverter 10 also swings without the lamp 1 and the coil 13 when on a resistor (e.g. 1170 Ohm) is connected to it, with a frequency that is higher (50 kHz) than the frequency when the lamp 1 is operated. As explained below, this frequency is lower when the lamp electrodes 2 and 3 are preheated ( approx. 25 kHz) than when the lamp 1 is on (approx. 35 kHz), so that the cold start tendency of the lamp 1 during the preheating of the electrodes 2 and 3 is eliminated by the lower frequency, and when the lamp burns, the greater light output of the higher frequency comes into its own.

Dazu ist ausser de Spule 13, die in üblicher Weise in Reihe mit der Entladungsstrecke der Lampe 1 liegt, die im Heizstromkreis der Elektroden 2 und 3 liegende Reihen­schlatung des Kondensators 15 (3300 pF), des Widerstands 16 (220 Ohm) und des SIDAC 17 (130 V) vorgesehen, deren Scheinwiderstand (ohne den SIDAC 17) im wesentlichen durch die Kapazität des Kondensators 15 bestimmt ist, die we­sentlich kleiner ist als die des Kondensators 37. Die Durchbruchspannung des SIDAC 17 ist höher als die Brenn­spannung der Lampe 1 bei der höheren Frequenz (35 kHz). Die Kapazität des Kondensators 15 und die Induktivität der Spule 13 sind so bemessen, dass bei der niedrigeren Frequenz (25 kHz), also vor dem Zünden der Lampe 1, ein angemessener Vorheizstrom durch die Elektroden 2 und 3 fliesst und dass der Spannungsabfall an der Reihenschal­tung 15, 16, 17 hinreichend unter der Spannung liegt, bei der die Lampe 1 mit der höheren Frequenz (35 kHz) brennt, und dass bei der höheren Frequenz mit der Induktivität der Spule 13 ein optimaler Entladungsstrom erreicht wird, wo­bei die Reihenschaltung 15, 16, 17 stromlos ist, weil die Brennspannung der Lampe 1 kleiner als die Durchbruch­spannung des SIDAC 17 ist.In addition to the coil 13, which is in the usual way in series with the discharge path of the lamp 1, the series connection of the capacitor 15 (3300 pF), the resistor 16 (220 ohm) and the SIDAC 17 in the heating circuit of the electrodes 2 and 3 (130 V) is provided, whose impedance (without the SIDAC 17) is essentially determined by the capacitance of the capacitor 15, which is significantly smaller than that of the capacitor 37. The breakdown voltage of the SIDAC 17 is higher than the operating voltage of the lamp 1 at higher frequency (35 kHz). The capacitance of the capacitor 15 and the inductance of the coil 13 are dimensioned such that an appropriate preheating current flows through the electrodes 2 and 3 at the lower frequency (25 kHz), i.e. before the lamp 1 is ignited, and that the voltage drop across the series circuit 15, 16, 17 is sufficiently below the voltage at which the lamp 1 burns at the higher frequency (35 kHz), and that an optimal discharge current is achieved at the higher frequency with the inductance of the coil 13, the series circuit 15, 16 , 17 is de-energized because the operating voltage of the lamp 1 is less than the breakdown voltage of the SIDAC 17.

Wenn der Wechselrichter 10 mit der Lampe 1 eingeschaltet wird, fliesst durch 37, 15, 16, 17 und 13 ein Hochfre­quenzstrom, dessen Frequenz unter der Wirkung des Kon­densators 15 und der Spule 13 niedriger (25 kHz) ist als die Frequenz (50 kHz), mit der der Wechselrichter 10 ohne diese Schaltungselemente schwingen würde. Der Hochfre­quenzstrom besteht aus in Abständen aufeinander folgen­den Halbwellen, deren jede sehr steil ansteigt, wenn die Durchbruchspannung des SIDAC 17 erreicht wird. Diese sehr plötzlichen Stromanstiege induzieren an der Spule 13 Spannungsimpulse, deren Spannung zum Zünden der Lampe 1 führt, sobald deren Elektroden 2 und 3 vorgeheizt sind. Wenn die Lampe 1 dann gezündet ist, fällt die Spannung an der Reihenschaltung 15,16, 17 auf die Brennspannung der Lampe 1, und damit fällt die Spannung am SIDAC 17 unter dessen Durchbruchspannung. Die Reihenschaltung 15, 16, 17 wird stromlos. Nun liegt nicht mehr die Kapazität des Kondensators 15 sondern die sehr viel kleinere Kapa­zität (50 bis 100 pF), die der SIDAC 17 im Sperrzustand darstellt, in Reihe mit der Selbstinduktion der Spule 13, denn bei der Reihenschaltung der Kapazitäten des Konden­sators 15 und des SIDAC 17 fällt erstere als die wesent­lich grössere ausser Betracht. Parallel zur Kapazität des SIDAC 17 und der Lampe 1 liegt noch die Kapazität der an diese angeschlossenen Leitungen. Die Gesamtkapazität ist wesentlich kleiner als die des Kondensators 15. Deshalb schwingt der Wechselrichter 10 nun mit der höheren Fre­quenz (35 kHz), und es wird die mit der höheren Frequenz höhere Lichtausbeute erzielt.When the inverter 10 is switched on with the lamp 1, a high-frequency current flows through 37, 15, 16, 17 and 13, the frequency of which, under the action of the capacitor 15 and the coil 13, is lower (25 kHz) than the frequency (50 kHz) with which the inverter 10 would vibrate without these circuit elements. The high-frequency current consists of successive half-waves, each of which increases very steeply when the breakdown voltage of the SIDAC 17 is reached. These very sudden current increases induce 13 voltage pulses on the coil, the voltage of which leads to the ignition of the lamp 1 as soon as the electrodes 2 and 3 are preheated. When the lamp 1 is then ignited, the voltage across the series circuit 15, 16, 17 drops to the operating voltage of the lamp 1, and thus the voltage across the SIDAC 17 falls below its breakdown voltage. The series circuit 15, 16, 17 is de-energized. Now there is no longer the capacitance of the capacitor 15 but the much smaller capacitance (50 to 100 pF), which the SIDAC 17 represents in the blocking state, in series with the self-induction of the coil 13, because in the series connection of the capacitances of the capacitor 15 and the SIDAC 17 is not considered as the much larger one. Parallel to the capacity of the SIDAC 17 and lamp 1 is the capacity of the lines connected to them. The total capacitance is considerably smaller than that of the capacitor 15. Therefore, the inverter 10 now vibrates at the higher frequency (35 kHz), and the higher luminous efficiency is achieved at the higher frequency.

Mit dem beschriebenen Wechselrichter 10 können auch meh­rere Leuchtstofflampen parallel gespeist werden, wobei jeder Lampe eine Spule 13 und ein Heizstrompfad 15, 16, 17 zuzuordnen ist.With the inverter 10 described, several fluorescent lamps can also be fed in parallel, with each lamp being assigned a coil 13 and a heating current path 15, 16, 17.

Zur Funkenstörung kann vor den Wechselrichter 10 oder den Gleichrichter 5 ein Störschutzfilter für die Harmoni­schen der Wechselrichterfrequenz, beispielsweise ein sog. "Boost Converter" geschaltet sein.For spark interference, an interference protection filter for the harmonics of the inverter frequency, for example a so-called “boost converter”, can be connected in front of the inverter 10 or the rectifier 5.

Zum Betrieb der Leuchtstofflampe 1 anstelle einer Glüh­lampe kann der Wchselrichter 10 zusammen mit dem Gleich­richter 5, 8 (und gewünschtenfalls einem Störschutzfil­ter) in ein Zwischenstück eingebaut sein, das einen dem Glühlampensockel entsprechenden, mit den Anschlüssen 6 und 7 von einer Glühlampenfassung aufzunehmenden Sockel und eine die Leuchtstofflampe 1 auswechselbar aufnehmende Fassung mit Kontakten für die Anschlüsse 11, 12, 18 und 19 hat.To operate the fluorescent lamp 1 instead of an incandescent lamp, the inverter 10 can be installed together with the rectifier 5, 8 (and, if desired, a noise protection filter) in an intermediate piece which has a base corresponding to the incandescent lamp base, with the connections 6 and 7 to be received by an incandescent lamp holder, and one the fluorescent lamp 1 has an interchangeable socket with contacts for the connections 11, 12, 18 and 19.

Versuche haben ergeben, dass die an der Anzahl der Ein­schaltvorgänge (Starts, Zündungen) gemessene Lebensdauer der Lampe mit der beschriebenen Schaltungsanordnung ca. 60 000 Einschaltungen beträgt, während sie mit bisheri­gen Vorschaltgeräten nur ca. 35 000 bis 40 000 Einschal­tungen betrug.Experiments have shown that the life span of the lamp, measured by the number of switch-on processes (starts, ignitions), is approximately 60,000 switch-ons with the circuit arrangement described, whereas it was only approx. 35,000 to 40,000 switch-ons with previous ballasts.

Claims (9)

1. Schaltungsanordnung mit einem Hochfrequenzerzeuger (10) für den Betrieb einer Leuchtstofflampe (1) mit vorzuheizen­den Elektroden (2, 3), dadurch gekennzeichnet, dass die Frequenz des Hochfrequenzerzeugers (10) während des Vor­heizens der Elektroden (2, 3) der Leuchtstofflampe (1) niedriger als bei brennender Lampe ist.1. Circuit arrangement with a high-frequency generator (10) for the operation of a fluorescent lamp (1) with electrodes to be preheated (2, 3), characterized in that the frequency of the high-frequency generator (10) during the preheating of the electrodes (2, 3) of the fluorescent lamp ( 1) is lower than when the lamp is on. 2. Anordnung nach Anspruch 1, dadurch gekennzeichnet, dass die Selbstinduktion einer in Reihe mit der Lampe (1) liegenden, den Vorheizstrom und den Brennstrom der Lampe begrenzenden Spule (13) mitbestimmend für die Frequenz des vom Hochfrequenzerzeuger (10) erzeugten Stromes ist, und dass im Elektrodenvorheizstromkreis die Spule (13) in Reihe mit einem Kondensator (15) und einem symmetri­schen Schaltungselement (17) liegt, das beim Ueberschrei­ten einer Spannung, die höher als die Brennspannung der Lampe (1) ist, stromdurchlässig wird.2. Arrangement according to claim 1, characterized in that the self-induction of a coil (13) which is in series with the lamp (1) and which limits the preheating current and the combustion current of the lamp also determines the frequency of the current generated by the high-frequency generator (10), and that in the electrode preheating circuit the coil (13) is connected in series with a capacitor (15) and a symmetrical circuit element (17) which becomes current-permeable when a voltage which is higher than the operating voltage of the lamp (1) is exceeded. 3. Anordnung nach Anspruch 2 oder 3, dadurch gekennzeich­net, dass die Spule (13) einen magnetischen Kern und dieser Kern einen Luftspalt hat.3. Arrangement according to claim 2 or 3, characterized in that the coil (13) has a magnetic core and this core has an air gap. 4. Anordnung nach Anspruch 2 oder 3, dadurch gekennzeich­net, dass das symmetrische Schaltungselement (17) ein SIDAC ist.4. Arrangement according to claim 2 or 3, characterized in that the symmetrical circuit element (17) is a SIDAC. 5. Anordnung nach einem der Ansprüche 2 bis 4, dadurch gekennzeichnet, dass in Reihe mit dem Kondensator (15) und dem symmetrischen Schaltungselement (17) ein Wider­stand (16) geschaltet ist.5. Arrangement according to one of claims 2 to 4, characterized in that a resistor (16) is connected in series with the capacitor (15) and the symmetrical circuit element (17). 6. Anordnung nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass der Wechselstromerzeuger ein Wechsel­richter (10) mit Stromrückkopplung durch einen bis in den magnetischen Sättigungsbereich seines Kern betriebe­nen Stromwandler (27) ist, dessen Primärwicklung (24) im die Lampe (1) beim Brennen und beim Vorheizen der Elektro­den (2, 3) speisenden Stromkreis liegt, und der (27) zwei Sekundärwicklungen (25, 26) hat, deren jede im Steuer­stromkreis eines von zwei steuerbaren Halbleiterelemen­ten (22, 23) liegt, die abwechselnd den Strom der einen und den Strom der zu dieser entgegengesetzten Halbwelle des erzeugten Hochfrequenzstroms leiten.6. Arrangement according to one of claims 1 to 5, characterized in that the alternating current generator is an inverter (10) with current feedback through a current converter (27) operated up to the magnetic saturation range of its core, the primary winding (24) of which in the lamp (1 ) when burning and when preheating the electrodes (2, 3) supply circuit, and (27) has two secondary windings (25, 26), each of which is in the control circuit one of two controllable semiconductor elements (22, 23), which alternately Conduct current of one and the current of the opposite half-wave of the generated high-frequency current. 7. Anordnung nach einem der Ansprüche 2 bis 6, dadurch gekennzeichnet, dass im die Leuchtstofflampe (1) beim Vorheizen ihrer Elektroden (2, 3) und beim Brennen spei­senden Hochfrequenzstromkreis (15, 16, 17; 1) ein Block­kondensator (37) liegt, dessen Kapazität ein Vielfaches der Kapazität des Kondensators (15) ist, der in Reihe mit dem symmetrischen Schaltungselement (17) geschaltet ist.7. Arrangement according to one of claims 2 to 6, characterized in that in the fluorescent lamp (1) when preheating its electrodes (2, 3) and when burning high-frequency circuit (15, 16, 17; 1) is a block capacitor (37) whose capacitance is a multiple of the capacitance of the capacitor (15) which is connected in series with the symmetrical circuit element (17). 8. Anordnung nach Anspruch 6 oder 7, dadurch gekenn­zeichnet, dass jedes der beiden steuerbaren Halbleiter­elemente (22, 23) durch eine Diode (42, 43) mit zum Halb­leiterelement entgegengesetzter Polung überbrückt ist.8. Arrangement according to claim 6 or 7, characterized in that each of the two controllable semiconductor elements (22, 23) is bridged by a diode (42, 43) with opposite polarity to the semiconductor element. 9. Anordnung nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass der Hochfrequenzerzeuger (5, 8, 10) in ein Zwischenstück eingebaut ist, das mit einem an­stelle einer Glühlampe von einer Glühlampenfassung auf­zunehmenden, mit den Stromversorgungsanschlüssen (6, 7) des Hochfrequenzerzeugers verbundenen Sockel und mit einer die Lampe (1) auswechselbar aufnehmenden Fassung verse­ hen ist, die für jede der heizbaren Lampenelektroden (2, 3) ein Kontaktpaar (11, 18; 12, 19) hat.9. Arrangement according to one of claims 1 to 8, characterized in that the high-frequency generator (5, 8, 10) is installed in an intermediate piece which with a instead of an incandescent lamp to be received by a bulb holder, with the power supply connections (6, 7) of High-frequency generator connected base and verse with a lamp (1) interchangeable socket hen, which has a pair of contacts (11, 18; 12, 19) for each of the heatable lamp electrodes (2, 3).
EP87119168A 1985-02-07 1985-04-04 Circuit arrangement for the high-frequency operation of fluorescent lamps having pre-heating electrodes Withdrawn EP0279073A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH55585A CH667958A5 (en) 1985-02-07 1985-02-07 CONTROL UNIT FOR A FLUORESCENT LAMP WITH ELECTRODES TO BE PREHEATED.
CH555/85 1985-02-07

Related Parent Applications (2)

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EP85901340A Division EP0179778B1 (en) 1984-04-09 1985-04-04 Adapter for releasibly connecting electric lighting apparatuses
EP85901340.1 Division 1985-04-04

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EP0279073A2 true EP0279073A2 (en) 1988-08-24
EP0279073A3 EP0279073A3 (en) 1990-06-27

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0024522A2 (en) * 1979-08-06 1981-03-11 Siemens Aktiengesellschaft Inverter for operating at least two gas discharge lamps
GB2068179A (en) * 1979-12-27 1981-08-05 Mitsubishi Electric Corp Discharge lamp lighting device
EP0056642A1 (en) * 1981-01-20 1982-07-28 Gerhard Prof. Dipl.-Phys. Wollank Method and circuit for heating, starting and driving or controlling the light current of low pressure gas discharge lamps
EP0075176A2 (en) * 1981-09-18 1983-03-30 Oy Helvar Electronic ballast for a discharge lamp

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0024522A2 (en) * 1979-08-06 1981-03-11 Siemens Aktiengesellschaft Inverter for operating at least two gas discharge lamps
GB2068179A (en) * 1979-12-27 1981-08-05 Mitsubishi Electric Corp Discharge lamp lighting device
EP0056642A1 (en) * 1981-01-20 1982-07-28 Gerhard Prof. Dipl.-Phys. Wollank Method and circuit for heating, starting and driving or controlling the light current of low pressure gas discharge lamps
EP0075176A2 (en) * 1981-09-18 1983-03-30 Oy Helvar Electronic ballast for a discharge lamp

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CH667958A5 (en) 1988-11-15
EP0279073A3 (en) 1990-06-27

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