EP0155729B1 - Circuit device for the ac operation of high-pressure discharge lamps - Google Patents

Circuit device for the ac operation of high-pressure discharge lamps Download PDF

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Publication number
EP0155729B1
EP0155729B1 EP85200313A EP85200313A EP0155729B1 EP 0155729 B1 EP0155729 B1 EP 0155729B1 EP 85200313 A EP85200313 A EP 85200313A EP 85200313 A EP85200313 A EP 85200313A EP 0155729 B1 EP0155729 B1 EP 0155729B1
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EP
European Patent Office
Prior art keywords
transistor
lamp
current
voltage
base
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85200313A
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German (de)
French (fr)
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EP0155729A1 (en
Inventor
Hans-Günther Ganser
Klaus Dr. Schäfer
Hans-Peter Dr. Stormberg
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Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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Application filed by Philips Patentverwaltung GmbH, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Patentverwaltung GmbH
Priority to AT85200313T priority Critical patent/ATE40253T1/en
Publication of EP0155729A1 publication Critical patent/EP0155729A1/en
Application granted granted Critical
Publication of EP0155729B1 publication Critical patent/EP0155729B1/en
Expired legal-status Critical Current

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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
    • H05B41/288—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 without preheating electrodes, e.g. for high-intensity discharge lamps, high-pressure mercury or sodium lamps or low-pressure sodium lamps
    • H05B41/292—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H05B41/2921—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
    • H05B41/2926—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions against internal abnormal circuit conditions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S315/00—Electric lamp and discharge devices: systems
    • Y10S315/07—Starting and control circuits for gas discharge lamp using transistors

Definitions

  • the invention relates to a circuit arrangement for AC operation of high-pressure gas discharge lamps with a current limiter arranged between the lamp and the mains AC voltage source and a high-frequency oscillator fed with direct current, which generates a high-frequency current superimposed on the mains AC lamp current through the lamp and an RF transformer and one in series with its primary winding Has lying, periodically on and off transistor, wherein a secondary winding of the transformer is connected in series with the lamp.
  • An ohmic resistor, a choke coil or an electronic ballast can be used as the current limiter.
  • a problem with the operation of high-pressure gas discharge lamps is the re-ignition after every zero crossing of the AC lamp current.
  • high re-ignition voltages may be required during the warm-up phase that they are no longer supplied by the ballast or the like and the lamp therefore goes out.
  • the lamps operated from an AC voltage source have therefore been overlaid with an additional high-frequency current.
  • a high voltage with a frequency of 1.6 to 200 kHz is additionally applied to ignite the lamps and is switched off again after the lamp is ignited.
  • This high HF voltage is above the ignition voltage of the lamps and should be at least 1000 V.
  • the RF oscillator must therefore be designed for such a voltage, for which relatively large high-performance components are required.
  • GB-PS 1 092199 a circuit arrangement for AC operation of gas discharge lamps is known, in which an additional high-frequency current is superimposed on the mains AC lamp current, which lowers the re-ignition voltage.
  • the high-frequency superimposition takes place during the full period of the AC lamp current.
  • the high-frequency current is approximately 10% of the average AC lamp current. This also requires a relatively large RF oscillator.
  • the invention has for its object to provide a circuit arrangement for AC operation of high pressure gas discharge lamps with a low re-ignition voltage, especially during the warm-up phase of the lamps, in which the individual components of the circuit - with the exception of the current limiter - are kept so small and so Low losses are said to make it possible to integrate the circuit into the lamp base or into the lamp base without thermal destruction of the components due to circuit losses.
  • This object is achieved in a circuit arrangement of the type mentioned at the outset according to the invention in that the ratio between the on and off time (duty cycle) of the transistor is chosen to be so small that the effective value of the high-frequency current coupled into the lamp is between 0.05 and 5% of the Mains alternating lamp current, and that an auxiliary device is provided, which bridges the base / emitter path of the transistor outside the vicinity of the zero crossings of the mains alternating lamp current with low resistance.
  • the invention is based on the knowledge that, surprisingly, a relatively small additional high-frequency power can be used to reduce the re-ignition voltage of high-pressure gas discharge lamps. This is less than 5% of the nominal lamp wattage.
  • the frequency of the high-frequency current can be approximately between 50 kHz and 1 MHz; a favorable value is e.g. 200 kHz.
  • the high-frequency voltage required is approximately between 100 and 200 V, in the order of magnitude of the lamp voltage. It has further been found that it is sufficient to avoid reignition difficulties if the high-frequency power, which is low in comparison to normal lamp power, is only coupled in in the vicinity of the zero crossings of the AC lamp current.
  • the pulse duty factor of the transistor can be set to the desired value in that the base of the transistor is connected to a second secondary winding of the HF transformer, the other end of which is connected to the DC supply voltage of the HF, which is divided via a voltage divider -Oszillators is applied, the duty cycle of the transistor can be reduced by lowering the divided supply DC voltage and / or by increasing the number of turns of the second secondary winding.
  • the auxiliary device has a further transistor bridging the base-emitter path of the first transistor, which turns the first transistor non-conductive when a predetermined instantaneous lamp current is exceeded by switching the base of the further transistor via a potentiometer with the rectified signal the current lamp current measuring current sensor is applied.
  • the current sensor used is e.g. an AC transformer or a measuring resistor.
  • the RF oscillator only with a low efficiency of z. B. 50% works, so that relatively cheap components can be used.
  • the power loss of the RF oscillator can be reduced to approximately 10% of the power loss during continuous operation.
  • the storage capacitor of the HF oscillator can charge to the peak value of the mains voltage in this case, since no power is withdrawn from it at the maximum of the mains voltage.
  • the voltage supplied by the RF oscillator in the zero crossings of the mains voltage is higher than in continuous operation, which is the advantage for the re-ignition behavior of the lamp and enables a smaller number of turns of the secondary winding lying in series with the lamp, thus reducing the size and cost of the HF Transformer are reduced.
  • the HF oscillator therefore only needs to oscillate during this warm-up phase.
  • the RF oscillator can be switched off to reduce the circuit losses.
  • this is done in that the base-emitter path of the transistor is bridged by a further transistor which switches the first transistor non-conductive depending on the average lamp voltage, by the base of the further transistor having the voltage a smoothing capacitor is applied, which is connected in parallel via a diode to a resistor of a second voltage divider, which in turn is parallel to the series connection of lamp and first secondary winding.
  • the smoothing capacitor is connected via a second diode and the potentiometer is tapped via a third diode with the Base of the further transistor connected. In this way, a mutual decoupling of the voltages of the potentiometer and the smoothing capacitor is achieved.
  • a and B are input terminals for connection to an AC network of z. B. 220 V, 50 Hz.
  • a high-pressure gas discharge lamp 2 is connected in series with a high-frequency oscillator 3 to these input terminals via a current limiter 1.
  • the outputs of the RF oscillator 3 are labeled C and D.
  • the current limiter 1 can be an ohmic resistor, a choke coil or an electronic ballast.
  • a high-frequency return capacitor 4 In parallel with the lamp 2 and the RF oscillator 3 there is a high-frequency return capacitor 4, which prevents high-frequency currents from being fed back into the AC voltage network.
  • the RF oscillator 3 In addition to the 50 Hz mains alternating lamp current, the RF oscillator 3 also couples a small high-frequency current into the lamp 2 with a frequency between 50 kHz and 1 MHz. Typically, the RF oscillator 3 would operate throughout the AC period. In order to reduce the circuit losses, the HF oscillator 3 should only oscillate in the vicinity of the zero crossings of the AC lamp current.
  • a current sensor 15, for. B. in the form of an AC converter which measures the lamp current and passes on to input terminals E and F of the RF oscillator 3.
  • Another input G of the RF oscillator 3 is connected to the electrode of the lamp 2 which is not connected to the output C of the RF oscillator 3.
  • FIG. 1 An embodiment of a suitable RF oscillator 3, which works on the principle of the flyback converter, is shown in FIG.
  • a bridge rectifier 5 with four diodes is connected to the input terminals A ' , B ' of the AC voltage network, the output of which is connected to a charging capacitor 6 in parallel.
  • the rectifier arrangement 5, 6 forms a DC voltage source for the actual HF oscillator 3.
  • This essentially consists of a high-frequency transformer 7 with a primary winding 8 and two secondary windings 9 and 10 and a transistor which can be switched on and off periodically with the primary winding 8 11.
  • the RF transformer 7 is connected with its primary winding 8 in series with the transistor 11 and a resistor 12 to the charging capacitor 6.
  • the first secondary winding 9 of the HF transformer 7 is in series with the lamp 2.
  • a voltage divider with its resistors 13 and 14 is also connected in parallel with the charging capacitor 6.
  • the voltage divider tap between the two resistors 13 and 14 is connected to one end of the second secondary winding 10 of the HF transformer 7, the other end of which is connected to the base of the transistor 11.
  • This circuit works as follows: The rectified mains voltage is present at the output of the bridge rectifier 5, as a result of which the charging capacitor 6 is charged. A current then flows out of it through the series connection of the pirmary winding 8 of the HF transformer 7, the switching transistor 11 and the resistor 12. The ratio of the voltage dividing resistors 13 and 14 is selected such that the divided DC supply voltage and there with the base voltage applied to the switching transistor 11 is sufficient to make the switching transistor 11 conductive. The rise time of this current is determined by the time constant resulting from the resistor 12 and the inductance of the primary winding 8.
  • the ratio between the on and off time (duty cycle) of the transistor 11 is determined by reducing the ratio of the voltage dividing resistors 14 to 13, i.e. by lowering the divided DC voltage for supplying the HF oscillator 3, and / or by increasing the number of turns of the second secondary winding 10 so small that the effective value of the high-frequency current coupled into the lamp 2 is between 0.05 and 5% of the AC lamp current.
  • the duty cycle of the transistor 11, once set, also determines the oscillation frequency of the RF oscillator 3.
  • the base-emitter path of the switching transistor 11 is bridged by a further transistor 16 in series with a resistor 17.
  • the signal applied by the current sensor 15 to the input terminals E and F of the RF oscillator 3 is rectified by a bridge rectifier 18 and fed to the base of the second transistor 16 via a potentiometer 19.
  • the size of the base voltage can be adjusted using the potentiometer 19.
  • the oscillator circuit described so far works as follows: Is the signal of the current sensor 15 small, i. H. in the vicinity of the current zero crossings, the base voltage of the transistor 16 is also small; transistor 16 is in the non-conductive state. In this case, the switching transistor 11 and thus the RF oscillator 3 operate as described above. If the lamp current and thus the base voltage of the transistor 16 now exceed a predetermined value, the transistor 16 becomes conductive, so that the smaller resistor 17 is connected in parallel with the resistor 14. As a result, the base voltage of the transistor 11 is lowered to such an extent that it remains in the non-conductive state and the RF oscillator 3 cannot therefore oscillate.
  • the threshold value of the lamp current, from which oscillation is prevented can be set via the potentiometer 19.
  • the lamp voltage present at the input G of the RF oscillator 3 is applied to a smoothing capacitor 23 via a voltage divider consisting of resistors 20 and 21 and a diode 22.
  • the time constant of the resistor 20 and the smoothing capacitor 23 is designed such that a voltage is present at the smoothing capacitor 23 which is proportional to the mean lamp voltage.
  • the voltage across the smoothing capacitor 23 is then applied to the base of the further transistor 16 via a second diode 24.
  • the voltage taken from the potentiometer 19 is applied to the base of the further transistor 16 via a third diode 25.
  • the two diodes 24 and 25 prevent mutual interference between the current-proportional signal from the potentiometer 19 and the voltage-proportional signal from the smoothing capacitor 23.
  • the HF oscillator 3 is switched off both outside the vicinity of the zero crossings of the lamp alternating current by the one tapped by the potentiometer 19 Voltage turns the further transistor 16 on, as well as when a predetermined mean lamp voltage is exceeded, in that the voltage taken from the smoothing capacitor 23 turns the further transistor 16 on.
  • the switching threshold for the lamp operating voltage is set via the voltage divider 20, 21 such that the RF oscillator 3 is only switched off after the lamp 2 has warmed up, ie. H. at a voltage that corresponds approximately to the normal lamp voltage.
  • the oscillation frequency of the RF oscillator was about 200 kHz with a peak voltage of about 200V.
  • the metal halide discharge lamps went through their warm-up phase without reignition problems.
  • the AC lamp current was approximately 0.6 A and the effective value of the high-frequency current was approximately 0.5 mA.
  • the lamp is connected in series with the RF oscillator.

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  • Circuit Arrangements For Discharge Lamps (AREA)

Abstract

1. A circuit arrangement for AC operation of high-pressure gas discharge lamps comprising a current limiter arranged between the lamp and the mains alternating voltage source and a high-frequency oscillator supplied with direct current and producing a high-frequency current through the lamp superimposed on the mains alternating lamp current, this oscillator comprising a high-frequency transformer and a transistor which is connected in series with the primary of this transformer and can be periodically switched on and switched off, a secondary of the transformer being connected in series with the lamp, characterized in that the ratio between switching-on time and switching-off time of the transistor (11) is chosen to be so small that the effective value of the high-frequency current coupled into the lamp (2) lies between 0.05 and 5% of the mains alternating lamp current, and in that an auxiliary device (15 to 19, 25) is provided, which shunts with low resistance the base-emitter path of the transistor outside the surroundings of the zero passages of the mains alternating lamp current.

Description

Die Erfindung bezieht sich auf eine Schaltungsanordnung zum Wechselstrombetrieb von Hochdruck-Gasentladungslampen mit einem zwischen Lampe und Netzwechselspannungsquelle angeordneten Strombegrenzer und einem mit Gleichstrom gespeisten Hochfrequenzoszillator, der einen dem Netzwechsellampenstrom überlagerten Hochfrequenzstrom durch die Lampe erzeugt und einen HF-Transformator und einen in Reihe mit dessen Primärwicklung liegenden, periodisch ein- und ausschaltbaren Transistor aufweist, wobei eine Sekundärwicklung des Transformators in Reihe mit der Lampe geschaltet ist. Als Strombegrenzer kann ein ohmscher Widerstand, eine Drosselspule oder ein elektronisches Vorschaltgerät benutzt werden.The invention relates to a circuit arrangement for AC operation of high-pressure gas discharge lamps with a current limiter arranged between the lamp and the mains AC voltage source and a high-frequency oscillator fed with direct current, which generates a high-frequency current superimposed on the mains AC lamp current through the lamp and an RF transformer and one in series with its primary winding Has lying, periodically on and off transistor, wherein a secondary winding of the transformer is connected in series with the lamp. An ohmic resistor, a choke coil or an electronic ballast can be used as the current limiter.

Ein Problem beim Betrieb von Hochdruck-Gasentladungslampen ist die Wiederzündung nach jedem Nulldurchgang des Netzwechsellampenstroms. Insbesondere bei Metallhalogenidentladungslampen können während derAufwärmphase derart hohe Wiederzündspannungen erforderlich sein, dass diese vom Vorschaltgerät o. dgl. nicht mehr geliefert werden und die Lampe deshalb erlischt. Zur Erleichterung der Zündung bzw. Wiederzündung von Hochdruck-Gasentladungslampen hat man daher die aus einer Netzwechselspannungsquelle betriebenen Lampen noch mit einem zusätzlichen Hochfrequenzstrom überlagert.A problem with the operation of high-pressure gas discharge lamps is the re-ignition after every zero crossing of the AC lamp current. In the case of metal halide discharge lamps in particular, such high re-ignition voltages may be required during the warm-up phase that they are no longer supplied by the ballast or the like and the lamp therefore goes out. In order to facilitate the ignition or re-ignition of high-pressure gas discharge lamps, the lamps operated from an AC voltage source have therefore been overlaid with an additional high-frequency current.

Bei einer aus der US-PS 4378514 bekannten Schaltungsanordnung dieser Art wird zum Zünden der Lampen zusätzlich eine hohe Spannung mit einer Frequenz von 1,6 bis 200 kHz angelegt, die nach dem Zünden der Lampe wieder abgeschaltet wird. Diese hohe HF-Spannung liegt über der Zündspannung der Lampen und dürfte mindestens 1000 V betragen. Der HF-Oszillator muss also für eine derartige Spannung ausgelegt sein, wofür relativ grosse Hochleistungsbauelemente erforderlich sind.In a circuit arrangement of this type known from US Pat. No. 4,378,514, a high voltage with a frequency of 1.6 to 200 kHz is additionally applied to ignite the lamps and is switched off again after the lamp is ignited. This high HF voltage is above the ignition voltage of the lamps and should be at least 1000 V. The RF oscillator must therefore be designed for such a voltage, for which relatively large high-performance components are required.

Auch aus der GB-PS 1 092199 ist eine Schaltungsanordnung zum Wechselstrombetrieb von Gasentladungslampen bekannt, bei der dem Netzwechsellampenstrom ein zusätzlicher Hochfrequenzstrom überlagert wird, wodurch sich die Wiederzündspannung erniedrigt. Die Hochfrequenzüberlagerung erfolgt während der vollen Periodendauer des Netzwechsellampenstroms. Der Hochfrequenzstrom beträgt etwa 10% des mittleren Netzwechsellampenstroms. Auch dies bedingt noch einen relativ grossen HF-Oszillator.From GB-PS 1 092199 a circuit arrangement for AC operation of gas discharge lamps is known, in which an additional high-frequency current is superimposed on the mains AC lamp current, which lowers the re-ignition voltage. The high-frequency superimposition takes place during the full period of the AC lamp current. The high-frequency current is approximately 10% of the average AC lamp current. This also requires a relatively large RF oscillator.

Der Erfindung liegt die Aufgabe zugrunde, eine Schaltungsanordnung zum Wechselstrombetrieb von Hochdruck-Gasentladungslampen mit einer niedrigen Wiederzündspannung, insbesondere während der Aufwärmphase der Lampen, zu schaffen, bei der die einzelnen Bauelemente der Schaltung - mit Ausnahme des Strombegrenzers - derart klein gehalten werden und mit so geringen Verlusten behaftet sein sollen, dass eine Integration der Schaltung in den Lampensockel bzw. in den Lampenfuss möglich wird, ohne dass eine thermische Zerstörung der Bauelemente aufgrund von Schaltungsverlusten auftreten kann.The invention has for its object to provide a circuit arrangement for AC operation of high pressure gas discharge lamps with a low re-ignition voltage, especially during the warm-up phase of the lamps, in which the individual components of the circuit - with the exception of the current limiter - are kept so small and so Low losses are said to make it possible to integrate the circuit into the lamp base or into the lamp base without thermal destruction of the components due to circuit losses.

Diese Aufgabe wird bei einer Schaltungsanordnung eingangs erwähnter Art gemäss der Erfindung dadurch gelöst, dass das Verhältnis zwischen Ein- und Ausschaltzeit (Tastverhältnis) des Transistors derart klein gewählt ist, dass der Effektivwert des in die Lampe eingekoppelten Hochfrequenzstroms zwischen 0,05 und 5% des Netzwechsellampenstroms beträgt, und dass eine Hilfsvorrichtung vorgesehen ist, welche die Basis/Emitterstrecke des Transistors ausserhalb der Umgebung der Nulldurchgänge des Netzwechsellampenstromes niederohmig überbrückt.This object is achieved in a circuit arrangement of the type mentioned at the outset according to the invention in that the ratio between the on and off time (duty cycle) of the transistor is chosen to be so small that the effective value of the high-frequency current coupled into the lamp is between 0.05 and 5% of the Mains alternating lamp current, and that an auxiliary device is provided, which bridges the base / emitter path of the transistor outside the vicinity of the zero crossings of the mains alternating lamp current with low resistance.

Die Erfindung geht von der Erkenntnis aus, dass man zur Verringerung der Wiederzündspannung von Hochdruck-Gasentladungslampen überraschenderweise mit einer relativ geringen zusätzlichen Hochfrequenzleistung auskommt. Diese beträgt weniger als 5% der nominalen Lampenleistung. Die Frequenz des Hochfrequenzstromes kann etwa zwischen 50 kHz und 1 MHz liegen; ein günstiger Wert ist z.B. 200 kHz. Die benötigte Hochfrequenzspannung liegt etwa zwischen 100 und 200 V, also in der Grössenordnung der Lampenbrennspannung. Es hat sich weiter herausgestellt, dass es zur Vermeidung von Wiederzündschwierigkeiten ausreicht, wenn die im Vergleich zur normalen Lampenleistung geringe Hochfrequenzleistung nur in der Umgebung der Nulldurchgänge des Netzwechsellampenstromes eingekoppelt wird.The invention is based on the knowledge that, surprisingly, a relatively small additional high-frequency power can be used to reduce the re-ignition voltage of high-pressure gas discharge lamps. This is less than 5% of the nominal lamp wattage. The frequency of the high-frequency current can be approximately between 50 kHz and 1 MHz; a favorable value is e.g. 200 kHz. The high-frequency voltage required is approximately between 100 and 200 V, in the order of magnitude of the lamp voltage. It has further been found that it is sufficient to avoid reignition difficulties if the high-frequency power, which is low in comparison to normal lamp power, is only coupled in in the vicinity of the zero crossings of the AC lamp current.

Das Tastverhältnis des Transistors lässt sich gemäss einer vorteilhaften Ausführungsform der Schaltungsanordnung nach der Erfindung dadurch auf den gewünschten Wert einstellen, dass die Basis des Transistors mit einer zweiten Sekundärwicklung des HF-Transformators verbunden ist, deren anderes Ende mit der über einen Spannungsteiler heruntergeteilten Versorgungsgleichspannung des HF-Oszillators beaufschlagt wird, wobei das Tastverhältnis des Transistors durch Erniedrigung der heruntergeteilten Versorgungsgleichspannung und/oder durch Vergrösserung der Windungszahl der zweiten Sekundärwicklung verringerbar ist.According to an advantageous embodiment of the circuit arrangement according to the invention, the pulse duty factor of the transistor can be set to the desired value in that the base of the transistor is connected to a second secondary winding of the HF transformer, the other end of which is connected to the DC supply voltage of the HF, which is divided via a voltage divider -Oszillators is applied, the duty cycle of the transistor can be reduced by lowering the divided supply DC voltage and / or by increasing the number of turns of the second secondary winding.

Bei einer bevorzugten Schaltungsanordnung nach der Erfindung weist die Hilfsvorrichtung einen die Basis-Emitterstrecke des ersten Transistors überbrückenden weiteren Transistor auf, der den ersten Transistor bei Überschreiten eines vorgegebenen momentanen Lampenstroms nichtleitend schaltet, indem die Basis des weiteren Transistors über ein Potentiometer mit dem gleichgerichteten Signal eines den momentanen Lampenstrom messenden Stromsensors beaufschlagt wird. Der verwendete Stromsensor ist z.B. ein Wechselstromwandler oder ein Messwiderstand.In a preferred circuit arrangement according to the invention, the auxiliary device has a further transistor bridging the base-emitter path of the first transistor, which turns the first transistor non-conductive when a predetermined instantaneous lamp current is exceeded by switching the base of the further transistor via a potentiometer with the rectified signal the current lamp current measuring current sensor is applied. The current sensor used is e.g. an AC transformer or a measuring resistor.

Hierbei reicht es aus, wenn der HF-Oszillator nur mit einem niedrigen Wirkungsgrad von z. B. 50% arbeitet, so dass relativ billige Bauelemente verwendet werden können. Die Verlustleistung des HF-Oszillators kann auf etwa 10% der Verlustleistung bei Dauerbetrieb verringert werden. Ausserdem kann sich der Speicherkondensator des HF-Oszillators in diesem Fall auf den Spitzenwert der Netzspannung aufladen, da ihm im Maximum der Netzspannung keine Leistung entzogen wird. Somit ist die in den Nulldurchgängen der Netzspannung vom HF-Oszillator gelieferte Spannung höher als bei kontinuierlichem Betrieb, was den Vorteil für das Wiederzündverhalten der Lampe ist und eine kleinere Windungszahl der in Reihe mit der Lampe liegenden Sekundärwicklung ermöglicht, wodurch Grösse und Kosten des HF-Transformators verringert werden.It is sufficient if the RF oscillator only with a low efficiency of z. B. 50% works, so that relatively cheap components can be used. The power loss of the RF oscillator can be reduced to approximately 10% of the power loss during continuous operation. In addition, the storage capacitor of the HF oscillator can charge to the peak value of the mains voltage in this case, since no power is withdrawn from it at the maximum of the mains voltage. Thus, the voltage supplied by the RF oscillator in the zero crossings of the mains voltage is higher than in continuous operation, which is the advantage for the re-ignition behavior of the lamp and enables a smaller number of turns of the secondary winding lying in series with the lamp, thus reducing the size and cost of the HF Transformer are reduced.

Wiederzündschwierigkeiten bei Hochdruck-Gasentladungslampen treten hauptsächlich während der Aufwärmphase der Lampen auf. Nur während dieser Aufwärmphase braucht daher der HF-Oszillator zu schwingen. Wenn die Lampenspannung nach der Aufwärmphase ihren Sollwert erreicht hat, kann der HF-Oszillator zur Verringerung der Schaltungsverluste abgeschaltet werden. Dies geschieht bei einer weiteren bevorzugten Ausführungsform der Schaltungsanordnung nach der Erfindung dadurch, dass die Basis-Emitterstrecke des Transistors durch einen weiteren Transistor überbrückt ist, der den ersten Transistor in Abhängigkeit von der mittleren Lampenspannung nichtleitend schaltet, indem die Basis des weiteren Transistors mit der Spannung eines Glättungskondensators beaufschlagt wird, der über eine Diode einem Widerstand eines zweiten Spannungsteilers parallel geschaltet ist, der wiederum parallel zur Reihenschaltung aus Lampe und erster Sekundärwicklung liegt.Reignition problems with high pressure gas discharge lamps mainly occur during the warm-up phase of the lamps. The HF oscillator therefore only needs to oscillate during this warm-up phase. When the lamp voltage has reached its setpoint after the warm-up phase, the RF oscillator can be switched off to reduce the circuit losses. In a further preferred embodiment of the circuit arrangement according to the invention, this is done in that the base-emitter path of the transistor is bridged by a further transistor which switches the first transistor non-conductive depending on the average lamp voltage, by the base of the further transistor having the voltage a smoothing capacitor is applied, which is connected in parallel via a diode to a resistor of a second voltage divider, which in turn is parallel to the series connection of lamp and first secondary winding.

Will man beide Massnahmen ergreifen, d. h. soll der HF-Oszillator nur in der Umgebung der Nulldurchgänge des Netzwechsellampenstroms schwingen und nach der Aufwärmphase der Lampen abgeschaltet werden, so sind gemäss einer Weiterbildung der Schaltungsanordnung nach der Erfindung der Glättungskondensator über eine zweite Diode und der Abgriff des Potentiometers über eine dritte Diode mit der Basis des weiteren Transistors verbunden. Auf diese Weise wird eine gegenseitige Entkoppelung der Spannungen des Potentiometers und des Glättungskondensators erreicht.If you want to take both measures, d. H. If the RF oscillator is to oscillate only in the vicinity of the zero crossings of the AC lamp current and be switched off after the lamps have warmed up, then according to a development of the circuit arrangement according to the invention, the smoothing capacitor is connected via a second diode and the potentiometer is tapped via a third diode with the Base of the further transistor connected. In this way, a mutual decoupling of the voltages of the potentiometer and the smoothing capacitor is achieved.

Ein Ausführungsbeispiel nach der Erfindung wird nunmehr anhand der Zeichnung näher beschrieben. Es zeigen:

  • Fig. 1 eine Schaltungsanordung zum Wechselstrombetrieb einer Hochdruck-Gasentladungslampe, die mit einem HF-Oszillator in Reihe liegt, der zusätzlich durch den Lampenstrom gesteuert wird,
  • Fig. die Schaltung des bei der Anordnung nach Fig. 1 verwendeten HF-Oszillators.
An embodiment of the invention will now be described with reference to the drawing. Show it:
  • 1 is a circuit arrangement for AC operation of a high pressure gas discharge lamp, which is in series with an RF oscillator, which is additionally controlled by the lamp current,
  • Fig. The circuit of the RF oscillator used in the arrangement of FIG. 1.

Mit A und B sind Eingangsklemmen zum Anschliessen an ein Wechselspannungsnetz von z. B. 220 V, 50 Hz, bezeichnet. An diese Eingangsklemmen ist über einen Strombegrenzer 1 eine Hochdruck-Gasentladungslampe 2 in Reihe mit einem Hochfrequenzoszillator 3 angeschlossen.With A and B are input terminals for connection to an AC network of z. B. 220 V, 50 Hz. A high-pressure gas discharge lamp 2 is connected in series with a high-frequency oscillator 3 to these input terminals via a current limiter 1.

Die Ausgänge des HF-Oszillators 3 sind mit C und D bezeichnet. Der Strombegrenzer 1 kann ein ohmscher Widerstand, eine Drosselspule oder ein elektronisches Vorschaltgerät sein. Parallel zur Lampe 2 und zum HF-Oszillator 3 liegt ein Hochfrequenzrückschlusskondensator 4, der verhindert, dass Hochfrequenzströme in das Wechselspannungsnetz zurückgekoppelt werden. Durch den HF-Oszillator 3 wird zusätzlich zum 50 Hz-Netzwechsellampenstrom ein geringer Hochfrequenzstrom mit einer Frequenz zwischen 50 kHz und 1 MHz in die Lampe 2 eingekoppelt. Üblicherweise würde der HF-Oszillator 3 während der gesamten Wechselstromperiode arbeiten. Zur Verringerung der Schaltungsverluste soll der HF-Oszillator 3 nur in der Umgebung der Nulldurchgänge des Netzwechsellampenstromes schwingen. Dafür ist zusätzlich ein Stromsensor 15, z. B. in Form eines Wechselstromwandlers, vorgesehen, der den Lampenstrom misst und an Eingangsklemmen E und F des HF-Oszillators 3 weitergibt. Ein weiterer Eingang G des HF-Oszillators 3 ist an die nicht mit dem Ausgang C des HF-Oszillators 3 verbundene Elektrode der Lampe 2 angeschlossen.The outputs of the RF oscillator 3 are labeled C and D. The current limiter 1 can be an ohmic resistor, a choke coil or an electronic ballast. In parallel with the lamp 2 and the RF oscillator 3 there is a high-frequency return capacitor 4, which prevents high-frequency currents from being fed back into the AC voltage network. In addition to the 50 Hz mains alternating lamp current, the RF oscillator 3 also couples a small high-frequency current into the lamp 2 with a frequency between 50 kHz and 1 MHz. Typically, the RF oscillator 3 would operate throughout the AC period. In order to reduce the circuit losses, the HF oscillator 3 should only oscillate in the vicinity of the zero crossings of the AC lamp current. For this purpose, a current sensor 15, for. B. in the form of an AC converter, which measures the lamp current and passes on to input terminals E and F of the RF oscillator 3. Another input G of the RF oscillator 3 is connected to the electrode of the lamp 2 which is not connected to the output C of the RF oscillator 3.

Ein Ausführungsbeispiel eines hierfür geeigneten HF-Oszillators 3, der nach dem Prinzip des Sperrwandlers arbeitet, ist in Fig. dargestellt. An die Eingangsklemmen A', B' des Wechselspannungsnetzes ist ein Brückengleichrichter 5 mit vier Dioden angeschlossen, dessem Ausgang ein Ladekondensator 6 parallel geschaltet ist. Die Gleichrichteranordnung 5, 6 bildet eine Gleichspannungsquelle für den eigentlichen HF-Oszillator 3. Dieser besteht im wesentlichen aus einem Hochfrequenztransformator 7 mit einer Primärwicklung 8 und zwei Sekundärwicklungen 9 und 10 und einem mit der Primärwicklung 8 in Reihe liegenden, periodisch an- und abschaltbaren Transistor 11. Der HF-Transformator 7 ist mit seiner Primärwicklung 8 in Reihe mit dem Transistor 11 und einem Widerstand 12 an den Ladekondensator 6 angeschlossen. Die erste Sekundärwicklung 9 des HF-Transformators 7 liegt in Reihe mit der Lampe 2. Parallel zum Ladekondensator 6 ist ferner ein Spannungsteiler mit seinen Widerständen 13 und 14 angeschlossen. Der Spannungsteilerabgriff zwischen den beiden Widerständen 13 und 14 steht mit einem Ende der zweiten Sekundärwicklung 10 des HF-Transformators 7 in Verbindung, deren anderes Ende mit der Basis des Transistors 11 verbunden ist.An embodiment of a suitable RF oscillator 3, which works on the principle of the flyback converter, is shown in FIG. A bridge rectifier 5 with four diodes is connected to the input terminals A ' , B ' of the AC voltage network, the output of which is connected to a charging capacitor 6 in parallel. The rectifier arrangement 5, 6 forms a DC voltage source for the actual HF oscillator 3. This essentially consists of a high-frequency transformer 7 with a primary winding 8 and two secondary windings 9 and 10 and a transistor which can be switched on and off periodically with the primary winding 8 11. The RF transformer 7 is connected with its primary winding 8 in series with the transistor 11 and a resistor 12 to the charging capacitor 6. The first secondary winding 9 of the HF transformer 7 is in series with the lamp 2. A voltage divider with its resistors 13 and 14 is also connected in parallel with the charging capacitor 6. The voltage divider tap between the two resistors 13 and 14 is connected to one end of the second secondary winding 10 of the HF transformer 7, the other end of which is connected to the base of the transistor 11.

Diese Schaltung arbeitet wie folgt: Am Ausgang des Brückengleichrichters 5 steht die gleichgerichtete Netzspannung an, wodurch der Ladekondensator 6 aufgeladen wird. Aus ihm fliesst dann ein Strom durch die Reihenschaltung der Pirmärwicklung 8 des HF-Transformators 7, des Schalttransistors 11 und des Widerstandes 12. Das Verhältnis der Spannungsteilerwiderstände 13 und 14 ist so gewählt, dass die heruntergeteilte Versorgungsgleichspannung und damit die am Schalttransistor 11 anliegende Basisspannung ausreicht, um den Schalttransistor 11 leitend zu machen. Die Anstiegszeit dieses Stromes wird durch die sich aus dem Widerstand 12 und der Induktivität der Primärwicklung 8 ergebende Zeitkonstante bestimmt. Mit dem Anstieg des Stromes durch die Primärwicklung 8 wird in der zweiten Sekundärwicklung 10 eine Spannung induziert, die der durch das Spannungsteilerverhältnis der Widerstände 13, 14 gegebenen Spannung entgegenwirkt und damit die Basisspannung des Transistors 11 auf derart kleine Werte absenkt, dass der Transistor 11 nichtleitend wird. Hierdurch wird der Strom durch die Primärwicklung 8 unterbrochen, wodurch wiederum die in die zweite Sekundärwicklung 10 induzierte Gegenspannung abgebaut wird. Damit kehrt der Transistor 11 in seinen Ausgangszustand zurück und der gesamte Vorgang beginnt von neuem, wodurch sich insgesamt in der Primärwicklung 8 eine hochfrequente Stromschwingung ergibt. Diese führt wiederum dazu, dass in der Sekundärwicklung 9 eine Hochfrequenzspannung induziert wird, die über die Ausgangsklemmen C und D in die Schaltungsanordnung nach Fig. 1 eingekoppelt wird.This circuit works as follows: The rectified mains voltage is present at the output of the bridge rectifier 5, as a result of which the charging capacitor 6 is charged. A current then flows out of it through the series connection of the pirmary winding 8 of the HF transformer 7, the switching transistor 11 and the resistor 12. The ratio of the voltage dividing resistors 13 and 14 is selected such that the divided DC supply voltage and there with the base voltage applied to the switching transistor 11 is sufficient to make the switching transistor 11 conductive. The rise time of this current is determined by the time constant resulting from the resistor 12 and the inductance of the primary winding 8. With the increase in the current through the primary winding 8, a voltage is induced in the second secondary winding 10, which counteracts the voltage given by the voltage divider ratio of the resistors 13, 14 and thus lowers the base voltage of the transistor 11 to such small values that the transistor 11 is non-conductive becomes. As a result, the current through the primary winding 8 is interrupted, which in turn reduces the countervoltage induced in the second secondary winding 10. The transistor 11 thus returns to its initial state and the entire process begins again, which results in a high-frequency current oscillation in the primary winding 8 as a whole. This in turn leads to the fact that a high-frequency voltage is induced in the secondary winding 9 and is coupled into the circuit arrangement according to FIG. 1 via the output terminals C and D.

Das Verhältnis zwischen An- und Ausschaltzeit (Tastverhältnis) des Transistors 11 wird durch Verkleinerung des Verhältnisses der Spannungsteilerwiderstände 14 zu 13, d.h. durch Erniedrigung der heruntergeteilten Gleichspannung zur Versorgung des HF-Oszillators 3, und/oder durch Vergrösserung der Windungszahl der zweiten Sekundärwicklung 10 derart klein gewählt, dass der Effektivwert des in die Lampe 2 eingekoppelten Hochfrequenzstromes zwischen 0,05 und 5% des Netzwechsellampenstroms beträgt. Das einmal eingestellte Tastverhältnis des Transistors 11 bestimmt darüber hinaus die Schwingungsfrequenz des HF-Oszillators 3.The ratio between the on and off time (duty cycle) of the transistor 11 is determined by reducing the ratio of the voltage dividing resistors 14 to 13, i.e. by lowering the divided DC voltage for supplying the HF oscillator 3, and / or by increasing the number of turns of the second secondary winding 10 so small that the effective value of the high-frequency current coupled into the lamp 2 is between 0.05 and 5% of the AC lamp current. The duty cycle of the transistor 11, once set, also determines the oscillation frequency of the RF oscillator 3.

Wie aus Fig.2 hervorgeht, ist die Basis- Emitterstrecke des Schalttransistors 11 durch einen weiteren Transistor 16 in Reihe mit einem Widerstand 17 überbrückt. Das vom Stromsensor 15 an die Eingangsklemmen E und F des HF-Oszillators 3 angelegte Signal wird durch einen Brükkengleichrichter 18 gleichgerichtet und über ein Potentiometer 19 der Basis des zweiten Transistors 16 zugeführt. Die Grösse der Basisspannung ist durch das Potentiometer 19 einstellbar.As can be seen from FIG. 2, the base-emitter path of the switching transistor 11 is bridged by a further transistor 16 in series with a resistor 17. The signal applied by the current sensor 15 to the input terminals E and F of the RF oscillator 3 is rectified by a bridge rectifier 18 and fed to the base of the second transistor 16 via a potentiometer 19. The size of the base voltage can be adjusted using the potentiometer 19.

Die bis jetzt beschriebene Oszillatorschaltung arbeitet folgendermassen: Ist das Signal des Stromsensors 15 klein, d. h. in der Umgebung der Stromnulldurchgänge, so ist die Basisspannung des Transistors 16 ebenfalls klein; der Transistor 16 befindet sich im nichtleitenden Zustand. In diesem Fall arbeitet der Schalttransistor 11 und damit der HF-Oszillator 3 wie oben beschrieben. Überschreitet nun der Lampenstrom und damit die Basisspannung des Transistors 16 einen vorgegebenen Wert, so wird der Transistor 16 leitend, so dass dem Widerstand 14 der kleinere Widerstand 17 parallel geschaltet wird. Hierdurch wird die Basisspannung des Transistors 11 so weit abgesenkt, dass er im nichtleitenden Zustand bleibt und der HF-Oszillator 3 somit nicht schwingen kann. Der Schwellwert des Lampenstromes, von dem an das Schwingen unterbunden wird, kann dabei über das Potentiometer 19 eingestellt werden.The oscillator circuit described so far works as follows: Is the signal of the current sensor 15 small, i. H. in the vicinity of the current zero crossings, the base voltage of the transistor 16 is also small; transistor 16 is in the non-conductive state. In this case, the switching transistor 11 and thus the RF oscillator 3 operate as described above. If the lamp current and thus the base voltage of the transistor 16 now exceed a predetermined value, the transistor 16 becomes conductive, so that the smaller resistor 17 is connected in parallel with the resistor 14. As a result, the base voltage of the transistor 11 is lowered to such an extent that it remains in the non-conductive state and the RF oscillator 3 cannot therefore oscillate. The threshold value of the lamp current, from which oscillation is prevented, can be set via the potentiometer 19.

Bei der Schaltung nach Fig. ist ausserdem noch die Möglichkeit vorgesehen, den HF-Oszillator 3 nach der Aufwärmphase der Lampe 2 abzuschalten, wodurch sich noch kleinere Verluste und damit eine noch geringere Erwärmung ergeben. Hierzu wird die am Eingang G des HF-Oszillators 3 anstehende Lampenspannung über einen aus Widerständen 20 und 21 bestehenden Spannungsteiler sowie eine Diode 22 auf einen Glättungskondensator 23 gegeben. Die Zeitkonstante des Widerstands 20 und des Glättungskondensators 23 ist so ausgelegt, dass am Glättungskondensator 23 eine Spannung ansteht, die der mittleren Lampenspannung proportional ist. Die am Glättungskondensator 23 anstehende Spannung wird dann über eine zweite Diode 24 auf die Basis des weiteren Transistors 16 gegeben. Gleichzeitig wird die am Potentiometer 19 abgenommene Spannung über eine dritte Diode 25 auf die Basis des weiteren Transistors 16 gegeben. Die beiden Dioden 24 und 25 verhindern dabei eine gegenseitige Beeinflussung des stromproportionalen Signals vom Potentiometer 19 sowie des spannungsproportionalen Signals vom Glättungskondensator 23. Auf diese Weise wird der HF-Oszillator 3 sowohl ausserhalb der Umgebung der Nulldurchgänge des Lampenwechselstromes abgeschaltet, indem die vom Potentiometer 19 abgegriffene Spannung den weiteren Transistor 16 leitend schaltet, als auch bei Überschreiten einer vorgegebenen mittleren Lampenspannung, indem die vom Glättungskondensator 23 abgenommene Spannung den weiteren Transistor 16 leitend schaltet. Die Schaltschwelle für die Lampenbrennspannung wird über den Spannungsteiler 20, 21 so eingestellt, dass ein Abschalten des HF-Oszillators 3 erst nach der Aufwärmphase der Lampe 2 erfolgt, d. h. bei einer Spannung, die etwa der normalen Lampenbrennspannung entspricht.In the circuit according to FIG. 1 there is also the possibility of switching off the RF oscillator 3 after the lamp 2 has warmed up, which results in even smaller losses and thus even less heating. For this purpose, the lamp voltage present at the input G of the RF oscillator 3 is applied to a smoothing capacitor 23 via a voltage divider consisting of resistors 20 and 21 and a diode 22. The time constant of the resistor 20 and the smoothing capacitor 23 is designed such that a voltage is present at the smoothing capacitor 23 which is proportional to the mean lamp voltage. The voltage across the smoothing capacitor 23 is then applied to the base of the further transistor 16 via a second diode 24. At the same time, the voltage taken from the potentiometer 19 is applied to the base of the further transistor 16 via a third diode 25. The two diodes 24 and 25 prevent mutual interference between the current-proportional signal from the potentiometer 19 and the voltage-proportional signal from the smoothing capacitor 23. In this way, the HF oscillator 3 is switched off both outside the vicinity of the zero crossings of the lamp alternating current by the one tapped by the potentiometer 19 Voltage turns the further transistor 16 on, as well as when a predetermined mean lamp voltage is exceeded, in that the voltage taken from the smoothing capacitor 23 turns the further transistor 16 on. The switching threshold for the lamp operating voltage is set via the voltage divider 20, 21 such that the RF oscillator 3 is only switched off after the lamp 2 has warmed up, ie. H. at a voltage that corresponds approximately to the normal lamp voltage.

Bei einem praktischen Ausführungsbeispiel zum Wechselstrombetrieb einer 45 W-Metallhalogenid-Hochdruckentladungslampe mit einer Brennspannung von 100 V wurden bei einer Schaltung nach Fig. folgende Schaltungsbauelemente verwendet:

  • Widerstand 12: 150 Ohm
  • Widerstand 17:390 Ohm
  • Widerstand 14:1,8 kohm
  • Widerstand 13: 120 kohm
  • Widerstand 20:82 kohm
  • Widerstand 21:6,8 kohm
  • Potentiometer 19: 1 kohm
  • Kondensator 4:1 nF
  • Kondensator 6: 0,5 µF
  • Kondensator 23: 0,2 µF
  • Transistor 11: BUX 86
  • Transistor 16: BC 107
  • Dioden 22, 24, 25: 1 N448
In a practical exemplary embodiment for AC operation of a 45 W metal halide high-pressure discharge lamp with an operating voltage of 100 V, the following circuit components were used in a circuit according to FIG.
  • Resistor 12: 150 ohms
  • Resistor 17: 390 ohms
  • Resistor 14: 1.8 kohm
  • Resistance 13: 120 kohm
  • Resistance 20:82 kohm
  • Resistance 21: 6.8 kohm
  • Potentiometer 19: 1 kohm
  • Capacitor 4: 1 nF
  • Capacitor 6: 0.5 µF
  • Capacitor 23: 0.2 µF
  • Transistor 11: BUX 86
  • Transistor 16: BC 107
  • Diodes 22, 24, 25: 1 N448

Windungsverhältnis des HF-Transformators 7: Primärwicklung 8:

  • Sekundärwicklung 10:
  • Sekundärwicklung 9 = 22:6:20
Winding ratio of the HF transformer 7: primary winding 8:
  • Secondary winding 10:
  • Secondary winding 9 = 22: 6: 20

Die Schwingungsfrequenz des HF-Oszillators betrug dabei etwa 200 kHz mit einer Spitzenspannung von etwa 200V. Die Metallhalogenidentladungslampen durchliefen ihre Aufwärmphase ohne Wiederzündprobleme. Der Netzwechsellampenstrom betrug etwa 0,6 A und der Effektivwert des Hochfrequenzstromes etwa 0,5 mA.The oscillation frequency of the RF oscillator was about 200 kHz with a peak voltage of about 200V. The metal halide discharge lamps went through their warm-up phase without reignition problems. The AC lamp current was approximately 0.6 A and the effective value of the high-frequency current was approximately 0.5 mA.

In den Ausführungsbeispielen ist die Lampe in Reihe mit dem HF-Oszillator geschaltet. Es ist jedoch auch möglich, den HF-Oszillator parallel zur Lampe zu schalten und die Verbindung durch zwei Kondensatoren herzustellen.In the exemplary embodiments, the lamp is connected in series with the RF oscillator. However, it is also possible to connect the RF oscillator in parallel to the lamp and to establish the connection using two capacitors.

Claims (5)

1. A circuit arrangement for AC operation of high-pressure gas discharge lamps comprising a current limiter arranged between the lamp and the mains alternating voltage source and a high-frequency oscillator supplied with direct current and producing a high-frequency current through the lamp superimposed on the mains alternating lamp current, this oscillator comprising a high-frequency transformer and a transistor which is connected in series with the primary of this transformer and can be periodically switched on and switched off, a secondary of the transformer being connected in series with the lamp, characterized in that the ratio between switching-on time and switching-off time of the transistor (11) is chosen to be so small that the effective value of the high-frequency current coupled into the lamp (2) lies between 0.05 and 5% of the mains alternating lamp current, and in that an auxiliary device (15 to 19, 25) is provided, which shunts with low resistance the base-emitter path of the transistor outside the surroundings of the zero passages of the mains alternating lamp current.
2. A circuit arrangement as claimed in Claim 1, characterized in that the base of the transistor (11) is connected to a second secondary (10) of the high-frequency transformer (7), whose other end is acted upon by the supply direct voltage of the high-frequency oscillator (3) divided via a voltage divider (13, 14) while the duty cycle of the transistor can be reduced by reduction of the divided supply direct voltage and/or by increase of the number of turns of the second secondary.
3. A circuit arrangement as claimed in Claim 1 or 2, characterized in that the auxiliary device has a further transistor (16) which shunts the base-emitter path of the first transistor (11) and which, when a given instantaneous lamp current is exceeded, switches the first transistor to the non-conductive state in that the base of the further transistor is acted upon via a potentiometer (19) by the rectified signal of a current sensor (15) measuring the instantaneous lamp current.
4. A circuit arrangement as claimed in Claim 1 or 2, characterized in that the base-emitter path of the transistor (11) is shunted by a further transistor (16), which switches the first transistor, in dependence upon the average lamp voltage, to the non-conductive state in that the base of the further transistor is acted upon by the voltage of a smoothing capacitor (23), which is connected via diode (22) parallel to a resistor (21) of a second voltage divider (20, 21), which is in turn connected parallel to the series arrangement of the lamp (2) and the first secondary (9).
5. A circuit arrangement as claimed in Claims 3 and 4, characterized in that the smoothing capacitor (23) is connected via the second diode (24) and the tapping on the potentiometer (19) via a third diode (25) to the base of the further transistor (16).
EP85200313A 1984-03-08 1985-03-04 Circuit device for the ac operation of high-pressure discharge lamps Expired EP0155729B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85200313T ATE40253T1 (en) 1984-03-08 1985-03-04 CIRCUIT ARRANGEMENT FOR AC OPERATION OF HIGH-PRESSURE GAS DISCHARGE LAMPS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843408426 DE3408426A1 (en) 1984-03-08 1984-03-08 CIRCUIT ARRANGEMENT FOR AC OPERATION OF HIGH PRESSURE GAS DISCHARGE LAMPS
DE3408426 1984-03-08

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EP0155729A1 EP0155729A1 (en) 1985-09-25
EP0155729B1 true EP0155729B1 (en) 1989-01-18

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EP (1) EP0155729B1 (en)
JP (1) JPS60207295A (en)
AT (1) ATE40253T1 (en)
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US5412222A (en) * 1993-06-30 1995-05-02 Eastman Kodak Company Storage phosphor reader having erase lamp feature failure detection
US5610477A (en) * 1994-04-26 1997-03-11 Mra Technology Group Low breakdown voltage gas discharge device and methods of manufacture and operation
GB2313929B (en) * 1995-10-20 1999-03-24 Hitachi Ltd Method and apparatus for controlling internal combustion engine for automotive vehicle
DE102005021595A1 (en) * 2005-05-10 2006-11-16 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Electronic cut in unit and process to operate a fluorescent lamp has half-bridge inverter and voltage divider with lamp between them and a changeable inverter ratio to give desired dc lamp current
DE102006018296A1 (en) * 2006-04-20 2007-10-25 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Arrangement and method for operating a high-pressure discharge lamp

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BE667410A (en) * 1964-07-28
US3411108A (en) * 1967-02-02 1968-11-12 Motorola Inc Starting circuits for magnetic core voltage inverter systems
US4087722A (en) * 1975-05-01 1978-05-02 American Ionetics, Inc. Apparatus and method for supplying power to gas discharge lamp systems
EP0003528B1 (en) * 1978-02-11 1981-09-30 Elstrom Control System AG Electronic device for controlling the light intensity of a gaseous discharge lamp without a heated cathode
US4378514A (en) * 1980-10-27 1983-03-29 General Electric Company Starting and operating circuit for gaseous discharge lamps
HU181323B (en) * 1981-05-08 1983-07-28 Egyesuelt Izzolampa High-frequency system of additional resistor for electric discharge lamp
US4392081A (en) * 1981-07-31 1983-07-05 General Electric Company Lighting unit
NL8104200A (en) * 1981-09-11 1983-04-05 Philips Nv ELECTRICAL CIRCUIT FOR OPERATING A GAS AND / OR VAPOR DISCHARGE LAMP.
US4464607A (en) * 1981-09-25 1984-08-07 General Electric Company Lighting unit

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ATE40253T1 (en) 1989-02-15
EP0155729A1 (en) 1985-09-25
US5025197A (en) 1991-06-18
CA1256936A (en) 1989-07-04
JPS60207295A (en) 1985-10-18
DE3408426A1 (en) 1985-09-12
DE3567787D1 (en) 1989-02-23

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