EP0594880B1 - Process and circuit for starting fluorescent lamps at a given temperature of the preheating electrodes - Google Patents

Process and circuit for starting fluorescent lamps at a given temperature of the preheating electrodes Download PDF

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Publication number
EP0594880B1
EP0594880B1 EP92118404A EP92118404A EP0594880B1 EP 0594880 B1 EP0594880 B1 EP 0594880B1 EP 92118404 A EP92118404 A EP 92118404A EP 92118404 A EP92118404 A EP 92118404A EP 0594880 B1 EP0594880 B1 EP 0594880B1
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EP
European Patent Office
Prior art keywords
tension
lamp
cathode
resistance
measured
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EP92118404A
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German (de)
French (fr)
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EP0594880A1 (en
Inventor
Felix Tobler
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Knobel AG Lichttechnische Komponenten
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Knobel AG Lichttechnische Komponenten
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Priority to EP92118404A priority Critical patent/EP0594880B1/en
Priority to DE59209173T priority patent/DE59209173D1/en
Priority to AT92118404T priority patent/ATE162922T1/en
Priority to US08/141,524 priority patent/US5455486A/en
Publication of EP0594880A1 publication Critical patent/EP0594880A1/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • 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
    • 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
    • H05B41/02—Details
    • H05B41/04—Starting switches
    • H05B41/042—Starting switches using semiconductor devices
    • H05B41/044—Starting switches using semiconductor devices for lamp provided with pre-heating electrodes
    • H05B41/046—Starting switches using semiconductor devices for lamp provided with pre-heating electrodes using controlled semiconductor devices

Definitions

  • the invention relates to a method according to the preamble of claim 1 and to a circuit arrangement to carry out the procedure.
  • the lamp cathodes are preheated by fluorescent lamps, before the ignition voltage to the fluorescent lamp is created. This will increase the lifespan of the fluorescent lamp significantly extended compared to a cold ignition. From EP-A-0 118 309 and DE-OS-32 02 445 Circuit arrangements are known in which the duration the preheating of the lamp cathodes is fixed. If the duration of preheating the lamp cathodes on this way it is set at essentially constant preheating current the different types of Fluorescent lamps with different resistance values Lamp cathodes heated unevenly. Because the optimal Lamp cathode temperature at ignition between Is 600 and 700 ° C, it is practically not possible an optimal duration for all types of fluorescent lamps the preheating time.
  • the object of the invention is therefore a Process for preheating and lighting fluorescent lamps to create, or a circuit arrangement for implementation the process, which is optimal and different Resistance values of the lamp cathodes independent Duration of the preheating time is achieved.
  • This known circuit arrangement corresponds the inductive operation of the fluorescent lamp at mains frequency (50-60 Hz).
  • the switch S is an electronic starter, e.g. in the Document EP-A-0 118 309.
  • the lamp cathode this switch is closed and opened after a pre-set period of time.
  • the switch is opened, the current flows through the Throttle Ld interrupted and by the at the throttle Ld induced voltage, the fluorescent lamp LL is ignited.
  • the value of the inductance of the inductor Ld by determines the lamp voltage and lamp current during operation the duration of the preheating time for the given preheating current so that the Fluorescent lamps ignited with the lowest-resistance cathode can be. This turns the fluorescent lamps with high-resistance lamp cathodes for too long with this preheating current operated what such fluorescent lamps unnecessary overheated and shortened their lifespan.
  • This series resonance circuit will used in electronic ballasts, in which the fluorescent lamp with higher frequency (20-90 kHz) is operated.
  • the frequency compared to the resonance frequency of the resonance circuit so changed that over the resonance capacitor and with that voltage above the fluorescent lamp none Ignition of the fluorescent lamp causes, and being an im substantially constant current through the lamp cathodes LK1 and LK2 flow and preheat them.
  • the fixed preselected duration of the preheating phase is the Frequency close to the resonant frequency of the resonant circuit brought and thereby the voltage across the resonance capacitor Cr so increased that the fluorescent lamp is ignited.
  • FIG. 3 shows the time profiles of the lamp cathode voltages V k of a low-resistance lamp cathode V KN and a high-resistance lamp cathode V KH when both lamp cathodes are preheated with essentially the same preheating current and for the same period of time.
  • the preheating current is switched on and the lamp cathode voltage V k is directly proportional to the resistance of the cold lamp cathodes.
  • the heating power P H currently delivered to the lamp cathodes is equal to the product of the preheating current in second power and the resistance of the lamp cathode.
  • the cathode temperature of the lamp is now determined before the ignition.
  • the lamp cathodes are made of tungsten wire with a temperature coefficient of 0.5% / K. From the measurement of the lamp cathode voltage V k , the temperature of the lamp cathode can be deduced directly if the voltage of the cold lamp cathode is known.
  • the Duration of preheat time determined so that a preselected Temperature of the lamp cathode is reached. Is this Temperature e.g. 600 ° C, the ratio of Resistance of the hot lamp cathode to the resistor the cold lamp cathode about 3. Ignition of the lamp can therefore be initiated if the resistance determined the hot cathode three times that previously determined Resistance of the cold cathode is.
  • FIG. 5 shows an exemplary embodiment of a circuit arrangement which enables the method according to the invention to be carried out.
  • the lamp cathode voltage V k is rectified and its peak value is measured on a capacitor C1.
  • the peak value of the first half-wave which corresponds to the voltage across the cold lamp cathode or the resistance of the cold cathode, is stored in a capacitor C2 using a sample and hold circuit SH.
  • the peak value of the current lamp cathode voltage increases continuously.
  • the duration of the preheating phase is determined so that the lamp cathodes are always brought to the same temperature.
  • V Kheiss / V Cold (R2 + R3) / R3
  • R2 2R3
  • the duration of the preheating phase is preferably limited to a maximum value (e.g. 2 seconds) if, for various reasons, e.g. preheating current that is too low or cathodes that are already hot after a brief power failure, it is not possible to reach the preselected ratio V Kheiss / V Kkalt .
  • FIG. 6 shows another circuit arrangement with which the method according to the invention can also be carried out.
  • the peak value of the lamp cathode voltage is measured with the aid of an A / D converter AD and the measured values are forwarded to a microprocessor MP.
  • a microprocessor MP By numerically comparing the value measured first at the beginning of the preheating phase and the current value of the lamp cathode voltage, it is possible to end the preheating phase when the preselected ratio V Kheiss / V Kkalt is reached and to apply the ignition voltage to precisely preheated lamp cathodes .
  • FIGS. 5 and 6 can be used regardless of whether the Fluorescent lamp with mains frequency or with higher frequencies is operated.
  • Figure 7 is another circuit arrangement shown with several fluorescent lamps. At several fluorescent lamps, it can be advantageous to Measurement of the average temperature of the lamp cathodes to detect multiple lamp cathode voltages in series.
  • the main purpose of the invention is based on the temperature of the lamp cathodes precisely coordinated, optimal duration of the preheating time to achieve.
  • the procedure is based on the temperature of the lamp cathodes precisely coordinated, optimal duration of the preheating time to achieve.

Abstract

For determining the effective cathode temperature of a lamp during the preheating phase, the resistance of the lamp cathode is measured. The lamp is started only when the temperature has reached for example 600@C. As a result, the service life of lamps can be increased considerably.

Description

Die Erfindung bezieht sich auf ein Verfahren gemäss Oberbegriff des Anspruchs 1 sowie auf eine Schaltungsanordnung zur Durchführung des Verfahrens.The invention relates to a method according to the preamble of claim 1 and to a circuit arrangement to carry out the procedure.

Bei hochwertigen Vorschaltgeräten zum Betrieb von Leuchtstofflampen werden die Lampenkathoden vorgeheizt, bevor die Zündspannung an die Leuchtstofflampe angelegt wird. Dadurch wird die Lebensdauer der Leuchtstofflampen gegenüber einer Kaltzündung wesentlich verlängert. Aus der EP-A-0 118 309 und der DE-OS-32 02 445 sind Schaltungsanordnungen bekannt, bei welchen die Dauer der Vorheizung der Lampenkathoden fest eingestellt ist. Wenn die Dauer der Vorheizung der Lampenkathoden auf diese Weise festgelegt ist, werden bei dem im wesentlichen konstanten Vorheizstrom die verschiedenen Typen von Leuchtstofflampen mit verschiedenen Widerstandswerten der Lampenkathoden ungleichmässig beheizt. Weil die optimale Temperatur der Lampenkathoden bei der Zündung zwischen 600 und 700°C beträgt, ist es praktisch nicht möglich, eine für alle Typen von Leuchtstofflampen optimale Dauer der Vorheizzeit fix einzustellen. Als Folge der festen Vorheizzeit und des im wesentlichen konstanten Vorheizstromes werden deshalb am selben Vorschaltgerät diejenigen Leuchtstofflampen mit niederohmigen Lampenkathoden unterheizt und die Leuchtstofflampen mit hochohmigen Lampenkathoden überheizt, was zu einer Verkürzung der Lebensdauer der Leuchtstofflampen und zu höheren Betriebskosten führt.For high-quality ballasts for operation The lamp cathodes are preheated by fluorescent lamps, before the ignition voltage to the fluorescent lamp is created. This will increase the lifespan of the fluorescent lamp significantly extended compared to a cold ignition. From EP-A-0 118 309 and DE-OS-32 02 445 Circuit arrangements are known in which the duration the preheating of the lamp cathodes is fixed. If the duration of preheating the lamp cathodes on this way it is set at essentially constant preheating current the different types of Fluorescent lamps with different resistance values Lamp cathodes heated unevenly. Because the optimal Lamp cathode temperature at ignition between Is 600 and 700 ° C, it is practically not possible an optimal duration for all types of fluorescent lamps the preheating time. As a result of the fixed Preheating time and the essentially constant preheating current are therefore those on the same ballast Fluorescent lamps with low-resistance lamp cathodes underheated and the fluorescent lamps with high resistance Lamp cathodes overheated, resulting in a shortening of the Fluorescent lamp life and higher operating costs leads.

Die Aufgabe der Erfindung ist es deshalb, ein Verfahren zum Vorheizen und Zünden von Leuchtstofflampen zu schaffen, bzw. eine Schaltungsanordnung zur Durchführung des Verfahrens, womit eine optimale und von verschiedenen Widerstandswerten der Lampenkathoden unabhängige Dauer der Vorheizzeit erzielt wird. The object of the invention is therefore a Process for preheating and lighting fluorescent lamps to create, or a circuit arrangement for implementation the process, which is optimal and different Resistance values of the lamp cathodes independent Duration of the preheating time is achieved.

Diese Aufgabe wird bei dem Verfahren der eingangs genannten Art durch die Merkmale des kennzeichnenden Teils des Anspruchs 1 gelöst. Die Schaltungsanordnung zur Durchführung des Verfahrens ist durch die Merkmale des Anspruchs 7 gekennzeichnet.This task is in the process of the beginning mentioned type by the characteristics of the characteristic Part of claim 1 solved. The circuit arrangement to carry out the procedure is by the features of claim 7 characterized.

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

  • Figur 1 eine schematische Darstellung einer Leuchtstofflampe, die mit einem mit Netzfrequenz arbeitenden Vorschaltgerät betrieben wird,
  • Figur 2 eine schematische Darstellung einer Leuchtstofflampe, die mit einem mit Hochfrequenz arbeitenden Vorschaltgerät betrieben wird,
  • Figur 3 zeitliche Abläufe der Lampenkathodenspannung in der Vorheizphase bei den bekannten Schaltungsanordnungen,
  • Figur 4 zeitliche Abläufe der Lampenkathodenspannungen in der Vorheizphase gemäss der Erfindung,
  • Figur 5 eine Ausführungsform der Schaltungsanordnung zur Durchführung des Verfahrens gemäss der Erfindung,
  • Figur 6 eine andere Ausführungsform der erfindungsgemässen Schaltungsanordnung, und
  • Figur 7 eine weitere Ausführungsform der Schaltungsanordnung gemäss der Erfindung mit mehreren Leuchtstofflampen.
    • Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawings. Show it:
  • FIG. 1 shows a schematic illustration of a fluorescent lamp which is operated with a ballast operating at the mains frequency,
  • FIG. 2 shows a schematic illustration of a fluorescent lamp which is operated with a ballast operating at high frequency,
  • FIG. 3 temporal sequences of the lamp cathode voltage in the preheating phase in the known circuit arrangements,
  • FIG. 4 temporal sequences of the lamp cathode voltages in the preheating phase according to the invention,
  • FIG. 5 shows an embodiment of the circuit arrangement for carrying out the method according to the invention,
  • 6 shows another embodiment of the circuit arrangement according to the invention, and
  • Figure 7 shows a further embodiment of the circuit arrangement according to the invention with a plurality of fluorescent lamps.

    • In Figur 1 sind eine Leuchtstofflampe LL mit ihren Lampenkathoden LK1, LK2, ein Starter S und eine Drossel Ld in einer Schaltungsanordnung schematisch dargestellt. Diese bekannte Schaltungsanordnung entspricht dem induktiven Betrieb der Leuchtstofflampe bei Netzfrequenz (50-60 Hz). Bei dem Schalter S handelt es sich um einen elektronischen Starter, wie er z.B. in der Schrift EP-A-0 118 309 beschrieben ist. In der Vorheizphase der Lampenkathoden wird dieser Schalter geschlossen und nach einer fest voreingestellten Zeitdauer geöffnet. Bei der Oeffnung des Schalters wird der Strom durch die Drossel Ld unterbrochen und durch die an der Drossel Ld induzierte Spannung wird die Leuchtstofflampe LL gezündet. Weil der Wert der Induktivität der Drossel Ld durch die Lampenspannung und den Lampenstrom im Betrieb bestimmt sind, muss die Dauer der Vorheizzeit für den somit gegebenen Vorheizstrom so gewählt werden, dass auch die Leuchtstofflampen mit der niederohmigsten Kathode gezündet werden können. Dadurch werden die Leuchtstofflampen mit hochohmigen Lampenkathoden zu lange mit diesem Vorheizstrom betrieben, was solche Leuchtstofflampen unnötig überheizt und ihre Lebensdauer verkürzt.In Figure 1, a fluorescent lamp LL with their lamp cathodes LK1, LK2, one starter S and one Choke Ld shown schematically in a circuit arrangement. This known circuit arrangement corresponds the inductive operation of the fluorescent lamp at mains frequency (50-60 Hz). The switch S is an electronic starter, e.g. in the Document EP-A-0 118 309. In the preheating phase the lamp cathode this switch is closed and opened after a pre-set period of time. When the switch is opened, the current flows through the Throttle Ld interrupted and by the at the throttle Ld induced voltage, the fluorescent lamp LL is ignited. Because the value of the inductance of the inductor Ld by determines the lamp voltage and lamp current during operation the duration of the preheating time for the given preheating current so that the Fluorescent lamps ignited with the lowest-resistance cathode can be. This turns the fluorescent lamps with high-resistance lamp cathodes for too long with this preheating current operated what such fluorescent lamps unnecessary overheated and shortened their lifespan.

    In Figur 2 ist eine Leuchtstofflampe LL mit einem Serieresonanzkreis mit einem Koppelkondensator Ck, einer Resonanzdrossel Lr und einem Resonanzkondensator Cr schematisch dargestellt. Dieser Serieresonanzkreis wird bei elektronischen Vorschaltgeräten verwendet, bei welchen die Leuchtstofflampe mit höherer Frequenz (20-90 kHz) betrieben wird. Im Vorheizbetrieb wird die Frequenz gegenüber der Resonanzfrequenz des Resonanzkreises so verändert, dass die über dem Resonanzkondensator und damit über der Leuchtstofflampe liegende Spannung keine Zündung der Leuchtstofflampe verursacht, und wobei ein im wesentlichen konstanter Strom durch die Lampenkathoden LK1 und LK2 fliesst und diese so vorheizt. Nach Ablauf der fest vorgewählten Dauer der Vorheizphase wird die Frequenz in die Nähe der Resonanzfrequenz des Resonanzkreises gebracht und dadurch die Spannung über dem Resonanzkondensator Cr so erhöht, dass die Leuchtstofflampe gezündet wird. Dieses Verfahren zum Vorheizen der Lampenkathoden mit vorgewählter Dauer der Vorheizzeit hat genau die gleichen Nachteile für die Lampenlebensdauer wie bei der Schaltungsanordnung von Figur 1 erläutert.In Figure 2, a fluorescent lamp LL with a series resonance circuit with a coupling capacitor Ck, a resonance choke Lr and a resonance capacitor Cr shown schematically. This series resonance circuit will used in electronic ballasts, in which the fluorescent lamp with higher frequency (20-90 kHz) is operated. In preheating mode, the frequency compared to the resonance frequency of the resonance circuit so changed that over the resonance capacitor and with that voltage above the fluorescent lamp none Ignition of the fluorescent lamp causes, and being an im substantially constant current through the lamp cathodes LK1 and LK2 flow and preheat them. After expiration the fixed preselected duration of the preheating phase is the Frequency close to the resonant frequency of the resonant circuit brought and thereby the voltage across the resonance capacitor Cr so increased that the fluorescent lamp is ignited. This procedure for preheating the lamp cathodes with pre-selected duration of the preheating time has exactly the same disadvantages for lamp life as in the circuit arrangement of Figure 1 explained.

    In Figur 3 sind die zeitlichen Verläufe der Lampenkathodenspannungen Vk einer niederohmigen Lampenkathode VKN und einer hochohmigen Lampenkathode VKH dargestellt, wenn beide Lampenkathoden mit im wesentlichen gleichem Vorheizstrom und während der gleichen Zeitdauer vorgeheizt werden. Im Zeitpunkt to wird der Vorheizstrom eingeschaltet und die Lampenkathodenspannung Vk ist direkt proportional dem Widerstand der kalten Lampenkathoden. Die an die Lampenkathoden momentan abgegebene Heizleistung PH ist gleich dem Produkt des Vorheizstromes in zweiter Potenz und des Widerstandes der Lampenkathode. Die jeweiligen Endtemperaturen der niederohmigen VKN und der hochohmigen VKH Lampenkathode im Zeitpunkt th sind in Figur 3 eingetragen. Es ist ersichtlich, dass bei fester Dauer der Vorheizzeit th-to die hochohmige Lampenkathode, die mit grösserer Leistung geheizt wird, gegenüber der niederohmigen Lampenkathode wesentlich höhere Temperaturen am Ende der Vorheizphase erreicht.FIG. 3 shows the time profiles of the lamp cathode voltages V k of a low-resistance lamp cathode V KN and a high-resistance lamp cathode V KH when both lamp cathodes are preheated with essentially the same preheating current and for the same period of time. At time t o the preheating current is switched on and the lamp cathode voltage V k is directly proportional to the resistance of the cold lamp cathodes. The heating power P H currently delivered to the lamp cathodes is equal to the product of the preheating current in second power and the resistance of the lamp cathode. The respective end temperatures of the low-resistance V KN and the high-resistance V KH lamp cathode at time t h are entered in FIG. 3. It can be seen that if the preheating time t h -t o is fixed , the high-resistance lamp cathode, which is heated with greater output, reaches significantly higher temperatures at the end of the preheating phase than the low-resistance lamp cathode.

    Gemäss der Erfindung wird nun die Kathodentemperatur der Lampe vor der Zündung ermittelt. Die Lampenkathoden bestehen aus Wolframdraht mit einem Temperaturkoeffizienten 0,5 %/K. Aus der Messung der Lampenkathodenspannung Vk kann man damit direkt auf die Temperatur der Lampenkathoden schliessen, wenn die Spannung der kalten Lampenkathode bekannt ist.According to the invention, the cathode temperature of the lamp is now determined before the ignition. The lamp cathodes are made of tungsten wire with a temperature coefficient of 0.5% / K. From the measurement of the lamp cathode voltage V k , the temperature of the lamp cathode can be deduced directly if the voltage of the cold lamp cathode is known.

    In Figur 4 sind die zeitlichen Verläufe der Lampenkathodenspannungen in einem vorteilhaften Fall gemäss der Erfindung dargestellt. In diesem Fall wird die Dauer der Vorheizzeit so bestimmt, dass eine vorgewählte Temperatur der Lampenkathode erreicht wird. Ist diese Temperatur z.B. ca. 600°C, so beträgt das Verhältnis des Widerstandes der heissen Lampenkathode zu dem Widerstand der kalten Lampenkathode etwa 3. Die Zündung der Lampe kann also eingeleitet werden, wenn der ermittelte Widerstand der heissen Kathode das Dreifache des zuvor ermittelten Widerstandes der kalten Kathode beträgt.4 shows the time profiles of the Lamp cathode voltages in an advantageous case shown according to the invention. In this case the Duration of preheat time determined so that a preselected Temperature of the lamp cathode is reached. Is this Temperature e.g. 600 ° C, the ratio of Resistance of the hot lamp cathode to the resistor the cold lamp cathode about 3. Ignition of the lamp can therefore be initiated if the resistance determined the hot cathode three times that previously determined Resistance of the cold cathode is.

    In Figur 5 ist ein Ausführungsbeispiel einer Schaltungsanordnung dargestellt, welche die Durchführung des erfindungsgemässen Verfahrens ermöglicht. Dabei wird die Lampenkathodenspannung Vk gleichgerichtet und ihr Spitzenwert an einem Kondensator C1 gemessen. Der Spitzenwert der ersten Halbwelle, welche der Spannung über der kalten Lampenkathode bzw. dem Widerstand der kalten Kathode entspricht, wird mit Hilfe einer Sample & Hold Schaltung SH in einem Kondensator C2 gespeichert. Durch Erhitzung der Lampenkathode steigt der Spitzenwert der momentanen Lampenkathodenspannung ständig an. Mit Hilfe eines Spannungsteilers R2/R3 und eines Komparators COM wird die Zeitdauer der Vorheizphase so bestimmt, dass die Lampenkathoden immer auf die gleiche Temperatur gebracht werden. Der Ausgang des Komparators wird nämlich bei folgender Bedingung umgeschaltet: VKheiss/VKkalt = (R2+R3)/R3 Das Verhältnis der Spannungen, bzw. der Kathodenwiderstände von 3:1, welches der beispielsweise angenommenen Temperatur von etwa 600°C entspricht, wird also bei ca. R2 = 2R3 erreicht, bzw. wenn die Lampenkathodenspannung in der Vorheizphase etwa verdreifacht wird.FIG. 5 shows an exemplary embodiment of a circuit arrangement which enables the method according to the invention to be carried out. The lamp cathode voltage V k is rectified and its peak value is measured on a capacitor C1. The peak value of the first half-wave, which corresponds to the voltage across the cold lamp cathode or the resistance of the cold cathode, is stored in a capacitor C2 using a sample and hold circuit SH. By heating the lamp cathode, the peak value of the current lamp cathode voltage increases continuously. With the aid of a voltage divider R2 / R3 and a comparator COM, the duration of the preheating phase is determined so that the lamp cathodes are always brought to the same temperature. The output of the comparator is switched under the following condition: V Kheiss / V Cold = (R2 + R3) / R3 The ratio of the voltages or the cathode resistances of 3: 1, which corresponds to the assumed temperature of about 600 ° C, is reached at approx. R2 = 2R3, or if the lamp cathode voltage is tripled in the preheating phase.

    Die Dauer der Vorheizphase wird vorzugsweise zusätzlich auf einen maximalen Wert begrenzt (z.B. 2 Sekunden), wenn aus verschiedenen Gründen, z.B. zu kleiner Vorheizstrom oder bereits heisse Kathoden nach einem kurzzeitigen Netzausfall, das Erreichen des vorgewählten Verhältnisses VKheiss/VKkalt nicht möglich ist.The duration of the preheating phase is preferably limited to a maximum value (e.g. 2 seconds) if, for various reasons, e.g. preheating current that is too low or cathodes that are already hot after a brief power failure, it is not possible to reach the preselected ratio V Kheiss / V Kkalt .

    In Figur 6 ist eine andere Schaltungsanordnung dargestellt, mit welcher die Durchführung des Verfahrens gemäss der Erfindung auch möglich ist. Hier wird der Spitzenwert der Lampenkathodenspannung mit Hilfe eines A/D Wandlers AD gemessen und die gemessenen Werte werden an einen Mikroprozessor MP weitergeleitet. Durch den numerischen Vergleich des zuerst gemessenen Wertes am Anfang der Vorheizphase und des momentanen Wertes der Lampenkathodenspannung ist es möglich, die Vorheizphase beim Erreichen des vorgewählten Verhältnisses VKheiss/ VKkalt zu beenden und die Zündspannung an genau vorgeheizte Lampenkathoden zu bringen.FIG. 6 shows another circuit arrangement with which the method according to the invention can also be carried out. Here the peak value of the lamp cathode voltage is measured with the aid of an A / D converter AD and the measured values are forwarded to a microprocessor MP. By numerically comparing the value measured first at the beginning of the preheating phase and the current value of the lamp cathode voltage, it is possible to end the preheating phase when the preselected ratio V Kheiss / V Kkalt is reached and to apply the ignition voltage to precisely preheated lamp cathodes .

    Die Schaltungsanordnungen in den Figuren 5 und 6 können unabhängig davon verwendet werden, ob die Leuchtstofflampe mit Netzfrequenz oder mit höheren Frequenzen betrieben wird.The circuit arrangements in FIGS. 5 and 6 can be used regardless of whether the Fluorescent lamp with mains frequency or with higher frequencies is operated.

    In Figur 7 ist eine weitere Schaltungsanordnung mit mehreren Leuchtstofflampen dargestellt. Bei mehreren Leuchtstofflampen kann es vorteilhaft sein, zur Messung der durchschnittlichen Temperatur der Lampenkathoden mehrere Lampenkathodenspannungen in Serie zu erfassen.In Figure 7 is another circuit arrangement shown with several fluorescent lamps. At several fluorescent lamps, it can be advantageous to Measurement of the average temperature of the lamp cathodes to detect multiple lamp cathode voltages in series.

    Der hauptsächliche Zweck des erfindungsgemässen Verfahrens ist eine auf die Temperatur der Lampenkathoden genau abgestimmte, optimale Dauer der Vorheizzeit zu erzielen. Durch die indirekte Messung der Temperatur der Lampenkathoden wird ein Verfahren geschaffen, bei welchem die Lebensdauer der Leuchtstofflampen unabhängig vom Typ der Leuchtstofflampe optimal ausgenützt werden kann. Nur mit einer genauen Vorheizung der Lampenkathoden lassen sich hohe Schaltzahlen und möglichst hohe Lebensdauer der Leuchtstofflampen erreichen.The main purpose of the invention The procedure is based on the temperature of the lamp cathodes precisely coordinated, optimal duration of the preheating time to achieve. By indirect measurement of the Temperature of the lamp cathodes a process is created where the life of fluorescent lamps optimal regardless of the type of fluorescent lamp can be exploited. Only with precise preheating the lamp cathodes can be high switching numbers and achieve the longest possible service life of the fluorescent lamps.

    Claims (11)

    1. Method for preheating and igniting at least one fluorescent lamp (LL) which has heatable lamp cathodes (LK1, LK2), these cathodes being first preheated, after the supply tension is switched on, by a circuit supplied by this tension in a way which does not provide across the lamp (LL) a tension sufficient to ignite it during the preheating phase, an ignition tension being applied to the fluorescent lamp after a certain duration of the preheating phase, the resistance of at least one of the lamp cathodes or the tension across such a cathode being measured during the preheating phase and its duration being determined in function of this measurement, characterized in that the resistance of the cold lamp cathode or the tension across it is measured and stored immediately after the supply voltage has been switched on, that thereafter instantaneous values of the resistance of the progressively hotter lamp cathode or of the tension across it are measured, that the stored value is compared with the instantaneous value of the resistance or of the tension across the warm lamp cathode, and that the igniting tension is applied to the fluorescent lamp (LL) when the ratio of the instantaneous value to the stored value of the resistance or of the tension across the lamp cathode reaches a predetermined level.
    2. Method according to claim 1, characterized in that one determines a maximal duration of the preheating phase, after which ignition is started regardless of the measurement.
    3. Method according to claim 1, characterized in that one choses the predetermined ratio of the resistance of the warm lamp cathode or the tension across it, to the resistance of the cold lamp cathode or the tension across it such that the lamp cathodes reach a temperature between 450 and 900°C before the igniting tension is applied.
    4. Method according to claim 2, characterized in that one choses the maximal duration of the preheating phase of the lamp cathode in the interval between 1 and 5 seconds.
    5. Method according to one of claims 1 to 4, characterized in that the lamp cathode tension is rectified, that the tension measured across the cold cathode is stored in a condenser (C2) and is compared through the use of a comparator (COM) with the rectified, instantaneous tension of the lamp after this latter tension has been reduced by a voltage divisor (R2, R3), until the stored tension of the cold lamp cathode coincides with the reduced, instantaneous tension of the warm lamp cathode, and in that the igniting tension is applied to the fluorescent lamp after the output signal of the comparator (COM) has switched.
    6. Method according to one of claims 1 to 4, characterized in that the tension of the lamp cathode is measured periodically with an analogue-digital converter, that the first measured value, which pertains to the cold cathode, is stored in the memory of a micro-processor, that the following measured values of the tension of the warm lamp cathode are compared to the stored value until a predetermined correspondence of the numerical values is attained, and that thereafter the igniting tension is applied to the fluorescent lamp.
    7. Electrical circuit for performing the method according to one of claims 1 to 6, with a measuring circuit for determining the tension of the lamp cathode, characterized in that it comprises a storage means for storing the measured value of the tension across the cold lamp cathode, and a comparison means for comparing the stored tension with a measured instantaneous tension.
    8. Electrical circuit according to claim 7, characterized in that it comprises a serial circuit connected in parallel to the lamp cathode and containing a diode, a resistance (R1) and a condenser (C1) intended for taking the peak value of the tension of the lamp cathode.
    9. Electrical circuit according to claim 7 or 8, characterized by an analogue-digital converter (AD) and a micro-processor for processing the output signals of the converter (AD).
    10. Electrical circuit according to claim 7 or 8, characterized by a sample and hold circuit (SH) which retains the tension of the cold lamp cathode, and by a comparator (COM) which compares the instantaneous tension with the tension of the cold lamp cathode.
    11. Electrical circuit according to one of claims 7 to 10 for driving a serial arrangement of at least two fluorescent lamps, neighbouring lamp cathodes (LK3; LK4; LK5; LK6) being connected in series and each such serial assembly being connected in parallel to a second winding of a corresponding additional separating transformer (TR5.2; TR6.2), the corresponding first winding of the separating transformer (TR5.1, TR6.1) being connected in series, characterized in that the circuit for measuring the tension of the lamp cathode is intended for measuring the tension of several lamp cathodes.
    EP92118404A 1992-10-28 1992-10-28 Process and circuit for starting fluorescent lamps at a given temperature of the preheating electrodes Expired - Lifetime EP0594880B1 (en)

    Priority Applications (4)

    Application Number Priority Date Filing Date Title
    EP92118404A EP0594880B1 (en) 1992-10-28 1992-10-28 Process and circuit for starting fluorescent lamps at a given temperature of the preheating electrodes
    DE59209173T DE59209173D1 (en) 1992-10-28 1992-10-28 Method and circuit arrangement for igniting fluorescent lamps at a predetermined temperature of the lamp cathodes
    AT92118404T ATE162922T1 (en) 1992-10-28 1992-10-28 METHOD AND CIRCUIT ARRANGEMENT FOR IGNITING FLUORESCENT LAMPS AT A PREDETERMINED TEMPERATURE OF THE LAMP CATHODES
    US08/141,524 US5455486A (en) 1992-10-28 1993-10-27 Method and circuitry for igniting fluorescent lamps at a predetermined temperature of their cathodes

    Applications Claiming Priority (1)

    Application Number Priority Date Filing Date Title
    EP92118404A EP0594880B1 (en) 1992-10-28 1992-10-28 Process and circuit for starting fluorescent lamps at a given temperature of the preheating electrodes

    Publications (2)

    Publication Number Publication Date
    EP0594880A1 EP0594880A1 (en) 1994-05-04
    EP0594880B1 true EP0594880B1 (en) 1998-01-28

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    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP92118404A Expired - Lifetime EP0594880B1 (en) 1992-10-28 1992-10-28 Process and circuit for starting fluorescent lamps at a given temperature of the preheating electrodes

    Country Status (4)

    Country Link
    US (1) US5455486A (en)
    EP (1) EP0594880B1 (en)
    AT (1) ATE162922T1 (en)
    DE (1) DE59209173D1 (en)

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    DE19501695B4 (en) * 1994-10-13 2008-10-02 Tridonicatco Gmbh & Co. Kg Ballast for at least one gas discharge lamp with preheatable lamp filaments
    FR2726426B1 (en) * 1994-10-28 1996-11-29 Sgs Thomson Microelectronics ELECTRONIC STARTER FOR FLUORESCENT LAMP
    US5696609A (en) * 1995-06-29 1997-12-09 Agfa Division, Bayer Corporation Illumination system for a flat-bed scanning system
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    Also Published As

    Publication number Publication date
    US5455486A (en) 1995-10-03
    DE59209173D1 (en) 1998-03-05
    EP0594880A1 (en) 1994-05-04
    ATE162922T1 (en) 1998-02-15

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