EP0852453B1 - Elektronisches Vorschaltgerät einer Gasentladungslampe mit Messung der Lampenleistung durch ein Gleichstromsignal - Google Patents

Elektronisches Vorschaltgerät einer Gasentladungslampe mit Messung der Lampenleistung durch ein Gleichstromsignal Download PDF

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Publication number
EP0852453B1
EP0852453B1 EP19970660149 EP97660149A EP0852453B1 EP 0852453 B1 EP0852453 B1 EP 0852453B1 EP 19970660149 EP19970660149 EP 19970660149 EP 97660149 A EP97660149 A EP 97660149A EP 0852453 B1 EP0852453 B1 EP 0852453B1
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EP
European Patent Office
Prior art keywords
lamp
current
load circuit
power
measuring
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Revoked
Application number
EP19970660149
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English (en)
French (fr)
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EP0852453A1 (de
Inventor
Erkki Ahonen
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Helvar Oy AB
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Helvar Oy AB
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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/36—Controlling
    • H05B41/38—Controlling the intensity of light
    • H05B41/39—Controlling the intensity of light continuously
    • H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
    • H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
    • H05B41/3925—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations by frequency variation

Definitions

  • the present invention relates to a dimmable or controllable electronic ballast for a low-pressure discharge lamp, especially a fluorescent lamp, whose operation is based on regulating the light output of a lamp by varying the frequency of a voltage supplied to the lamp.
  • the invention relates to a circuit system for accurately measuring a power delivered by such a ballast to a lamp load so as to find out the proportion of power required for sustaining discharge of the lamp.
  • the ballast depicted in fig. 1 includes a rectifier V1 connected to a supply voltage UV, a smoothing capacitor C1, a high-frequency oscillator A1, as well as transistors TR1 and TR2 constituting a halfbridge circuit.
  • a lamp LL is coupled as part of a resonance circuit, constituted by a capacitor C2 and an inductance L2 and supplied by the push-pull transistors TR1 and TR2.
  • a filament pre-heating current for the cathodes of the lamp LL during a switch-on sequence of the lamp is conducted by way of a capacitor C3.
  • the oscillator A1 is provided with a control circuit CO1- CO2, wherethrough a control signal influences the oscillating frequency of the oscillator.
  • the electronic ballast must generally be provided with a separate safety feature in anticipation of certain special circumstances, such as over- or undervoltage in an electrical network supplying the ballast, overheating of the device, a lamp missing, or breaking of the lamp cathodes, as described e.g. in the Applicant's patent application FI 955695.
  • a power supplied to the lamp LL be measured at a sufficient accuracy.
  • This measurement information is utilized in the operation of a control block A1 in such a manner that the lamp LL can be supplied in a stable fashion with a power proportional to the voltage between control lines CO1 and CO2 for regulating the light output of the lamp.
  • the power supplied to the lamp load LL by the halfbridge-connected transistor circuit TR1 and TR2 consists of two components: an actual lamp power, which sustains a light-generating discharge in the lamp, and a filament power, which is used for heating the lamp cathodes.
  • Other components of the load circuit experience power losses as well. Especially at lower regulation levels, the power consumed by a lamp discharge being low, the power of cathode incandescence constitutes a considerable portion of the power of the entire circuit.
  • a problem with the ballast shown in fig. 1 is the measurement of a load power in such a manner that the actual lamp power can be measured at a sufficient accuracy without the power required by incandescence having a significant effect on the measuring result.
  • EP-589 081 discloses an alternative way of providing a measurement of the "arc discharge” current by using a preheating transformer; the voltage sensed at resistor (R1), through which the lamp current is passing, being representative of the "arc discharge” current.
  • WO 97/01945 shows a current sensor impedance for measuring lamp current and another impedance for measuring a current proportional to lamp filament current, the ratio of the values of the impedances being chosen according to ratio of current amplitudes at certain branches of the circuit.
  • a signal which is a measure for a difference between the voltages across the impedances is used as a measure for the lamp current.
  • An object of the invention is to resolve this problem involving measuring technology and to provide a ballast wherein the inaccuracy factors associated with the measurement of a lamp power can be sufficiently eliminated by an electronic circuit that is simple in design.
  • the effective energy consumed by the halfbridge TR1 - TR2 transfers primarily to a load circuit C2, L2, LL, and C3.
  • the current through either supply of the halfbridge is proportional to the energy consumed by the load circuit, if the supply voltage of the halfbridge is maintained constant.
  • the load circuit is constituted by an inductance or coil L2, a lamp LL, and capacitors C2, C3.
  • the lamp LL is the only one to consume effective power.
  • the energy consumed by the lamp LL is divided into an energy input required by the lamp discharge and an energy consumed by filaments. In terms of the output of light, the energy of a lamp current is interesting.
  • the regulation functions well as long as the lamp power is higher than the filament power.
  • the regulation becomes inaccurate. Depending on the type of lamp, this occurs between 10...20 % light level.
  • the effect of the filament power must be eliminated from a measuring signal. This can be done by measuring e.g. a voltage existing across one of the cathodes of the lamp LL, as set forth in the Applicant's patent application EP-853 445. As for these measuring methods, a problem is how to achieve a sufficient accuracy, since there are losses also in other circuit elements, such as ignition capacitors, lamp inductances, and switching transistors.
  • An object of this invention is to introduce a circuit connection for a ballast, whereby the power of a low-pressure discharge lamp, especially a fluorescent lamp, can be measured in such a way that said inaccuracy factors in the measurement can be eliminated.
  • This is performed by feeding through the lamp a separate direct-current signal, which is used for producing a direct-voltage signal proportional to the effective resistance of the lamp.
  • Said direct current through the lamp brings about a further advantage that the dark stripes visible on the surface of the lamp bulb, or a so-called striation effect, at lower regulation levels and especially at lower operating temperatures, can be avoided.
  • Fig. 2 of the drawing illustrates one embodiment of the above-described measuring principle.
  • the total power of a load circuit is measured by using a resistance R2, the voltage produced thereby and proportional to the current of a halfbridge TR1 - TR2 being filtered with elements R3 and C4 as well as being conducted to an oscillator block A1.
  • the operation of the oscillator block A1 is here divided in two sections, whereof a sub-block II handles the processing of measuring signals and a sub-block I the control of the halfbridge transistors TR1 and TR2.
  • a resistance R4 is used for developing a direct-current component in an alternating current passing through the lamp LL.
  • the lamp has a substitution resistance of about 275 ohms, at a 50 % light level about 600 ohms, and at a 5 % light level about 14 kilo-ohms.
  • the direct current component supplied to a lamp is 1,5 mA, the result will be a direct voltage of about 20 V across the lamp.
  • the direct voltage measurement has a wide dynamic range and the measuring signal can be readily utilized in the control block of a ballast.
  • useful components include a.o. a bipolar transistor and various designs of field effect transistors. It is also obvious that the control signal of the oscillator A1 in the circuit CO1 - CO2 can be digital as well, the sub-block II including necessary circuit elements for processing digital information, e.g. by means of a programmable micro-controller.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)

Claims (3)

  1. Steuerbares oder dimmbares elektronisches Vorschaltgerät für eine Niederdruck-Entladungslampe, insbesondere eine Floureszenzlampe, umfassend
    einen Halbbrücken-Wechselrichter (TR1, TR2, V2, V3) oder eine entsprechende Wechselstromquelle zur Lieferung von Wechselstromleistung hoher Frequenz an eine Lastschaltung,
    eine Lastschaltung, in welcher eine Entladungslampe (LL) angeschlossen werden soll, wobei die Lastschaltung eine Strombegrenzungs-Induktivität (L2) in Reihe mit der Lampe besitzt, wenn die Lampe angeschlossen ist, einen Filamentstrom-Zuführkondensator (C3) parallel mit der Lampe, wenn die Lampe angeschlossen ist, und ein Element (R4) zur Erzeugung eines durch die Lampe laufenden Gleichstroms, wobei die Lastschaltung mit dem Mittenpunkt des Halbbrücken-Wechselrichters oder der entsprechenden Wechselstromquelle verbunden ist,
    einen Regelungs- oder Steuerungs-Block (A1/I, II) zur Einstellung der Frequenz des Wechselrichters oder einer entsprechenden Wechselstromquelle, zur Regelung der Lichtleistung der Lampe,
    Elemente (R2, R3, C4) zur Messung eines der Lastschaltungsleistung proportionalen Stroms und zur Führung der Messinformation (Umeas) an den Regelungs- oder Steuerungs-Block, und
    Elemente (R5, C5, R6), welche direkt parallel mit der Lampe sind, wenn sie angeschlossen ist, zur Messung der an der Lampe entwickelten Gleichspannung durch den Gleichstrom, der von dem Gleichstrom-Erzeugungselement (R4) erzeugt wird, und zur Führung der Messinformation zum Regelungs- oder Steuerungs-Block (A1/I, II),
    so dass ein Messsignal proportional zur Lampenleistung als Differenz zwischen jenen Messinformationsstücken erzeugt wird.
  2. Vorschaltgerät nach Anspruch 1, wobei jedes der Strom- und Spannungs-Messelemente (R2, R3, C4 und R5, C5, R6) mindestens einen Widerstand (R2; R6) enthält, und mindestens einen Kondensator (C4; C5) enthält, der parallel mit dem Widerstand geschaltet ist.
  3. Vorschaltgerät nach Anspruch 1 oder 2, wobei das Element, das den durch die Lampe laufenden Gleichstrom erzeugt, ein Widerstand (R4) ist, welcher parallel mit einem Kondensator (C2) geschaltet ist, der in der Lastschaltung zwischen der Induktivität (L2) und der Lampe (LL) enthalten ist, und dass die Gleichstrommesselemente (R5, R6, C5) zwischen der Verbindung des Widerstands (R4) mit dem ersten Lampenanschluss und dem entgegengesetzten Lampenanschluss angeschlossen sind.
EP19970660149 1997-01-03 1997-12-19 Elektronisches Vorschaltgerät einer Gasentladungslampe mit Messung der Lampenleistung durch ein Gleichstromsignal Revoked EP0852453B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI970018 1997-01-03
FI970018A FI101188B (fi) 1997-01-03 1997-01-03 Purkauslampun elektroninen liitäntälaite, jossa on lampputehon mittaus DC-signaalin avulla

Publications (2)

Publication Number Publication Date
EP0852453A1 EP0852453A1 (de) 1998-07-08
EP0852453B1 true EP0852453B1 (de) 2000-08-16

Family

ID=8547419

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19970660149 Revoked EP0852453B1 (de) 1997-01-03 1997-12-19 Elektronisches Vorschaltgerät einer Gasentladungslampe mit Messung der Lampenleistung durch ein Gleichstromsignal

Country Status (3)

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EP (1) EP0852453B1 (de)
DE (1) DE69702829T2 (de)
FI (1) FI101188B (de)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI107580B (fi) * 1999-03-30 2001-08-31 Innoware Oy Loistelampun syöttökytkentä
US7679293B2 (en) 2007-12-20 2010-03-16 General Electric Company Anti-striation circuit for current-fed ballast
US7982452B2 (en) 2009-07-30 2011-07-19 Infineon Technologies Austria Ag Detection of a load state of a half-bridge
WO2011055158A1 (en) * 2009-11-03 2011-05-12 City University Of Hong Kong A passive lc ballast and method of manufacturing a passive lc ballast
US8638048B2 (en) 2011-04-12 2014-01-28 Infineon Technologies Ag Circuit for determining an average value
DE102011082245B3 (de) * 2011-09-07 2013-01-17 Osram Ag Elektronisches Vorschaltgerät und Verfahren zum Betreiben einer Entladungslampe
DE102011082239B3 (de) * 2011-09-07 2013-01-17 Osram Ag Elektronisches Vorschaltgerät und Verfahren zum Betreiben einer Entladungslampe

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0422255B1 (de) * 1989-10-09 1994-03-02 Siemens Aktiengesellschaft Elektronisches Vorschaltgerät
DE4039498B4 (de) * 1990-07-13 2006-06-29 Lutron Electronics Co., Inc. Schaltkreis und Verfahren zum Dimmen von Gasentladungslampen
EP0589081B1 (de) * 1992-09-24 1997-01-15 Knobel Ag Lichttechnische Komponenten Schaltungsanordnung zum Betrieb einer Leuchtstofflampe und zur Messung des Lampenstroms
CN1124778C (zh) * 1995-06-29 2003-10-15 皇家菲利浦电子有限公司 电路配置

Also Published As

Publication number Publication date
DE69702829D1 (de) 2000-09-21
FI970018A0 (fi) 1997-01-03
EP0852453A1 (de) 1998-07-08
FI101188B1 (fi) 1998-04-30
DE69702829T2 (de) 2000-12-07
FI101188B (fi) 1998-04-30

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