EP0853445A1 - Elektronisches Vorschaltgerät mit Helligkeitssteuerung und Messung der Lampenleistung - Google Patents

Elektronisches Vorschaltgerät mit Helligkeitssteuerung und Messung der Lampenleistung Download PDF

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Publication number
EP0853445A1
EP0853445A1 EP97660148A EP97660148A EP0853445A1 EP 0853445 A1 EP0853445 A1 EP 0853445A1 EP 97660148 A EP97660148 A EP 97660148A EP 97660148 A EP97660148 A EP 97660148A EP 0853445 A1 EP0853445 A1 EP 0853445A1
Authority
EP
European Patent Office
Prior art keywords
lamp
power
current
filament
load circuit
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.)
Withdrawn
Application number
EP97660148A
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English (en)
French (fr)
Inventor
Erkki Ahonen
Jari Heine
Hannu Vihinen
Teijo Viljanen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Helvar Oy AB
Original Assignee
Helvar Oy AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Helvar Oy AB filed Critical Helvar Oy AB
Publication of EP0853445A1 publication Critical patent/EP0853445A1/de
Withdrawn legal-status Critical Current

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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 voltage supplied to the lamp.
  • the invention relates to a method and a circuit system for accurately measuring the power supplied by such a ballast to a lamp load so as to find out the proportional share of power consumed by the lamp cathodes.
  • the structure of electronic ballasts for low-pressure discharge lamps is prior known from the Applicant's patent No. 64478 as well as the theoretical foundations from the Applicant's patent No. FI 63314.
  • the Applicant's patent No. FI 63146 discloses the structure and operation of a low-voltage controlled electronic ballast for gaining a light output proportional to an external control signal.
  • the ballast shown 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 semi- or half-bridge circuit.
  • a lamp LL is connected as part of a resonance circuit, constituted by a capacitor C2 and a winding L2 and supplied by the push-pull transistors TR1 and TR2.
  • a filament pre-heating current for the cathodes of the lamp LL at a switch-on stage of the lamp is passed via a capacitor C3.
  • the oscillator Al is provided with a control connection CO1 - CO2, wherethrough the control signal influences the oscillating frequency of the oscillator.
  • the electronic ballast must generally be fitted with a separate safety feature for against certain special circumstances, such as over- or undervoltage in an electric network supplying the ballast, overheating of the device, a missing lamp, or breaking of the lamp cathodes, as described e.g. in the Applicant's patent application FI 955695.
  • heating the cathodes of low-pressure discharge lamps during the switch-on sequence of a lamp has a positive contribution to the service life and operating characteristics of the lamp.
  • the appropriately dimensioned filament power can be used for prolonging the service life of a lamp by reducing a stress applied to the lamp cathodes and especially to the emission material layer serving as a coating therefor. At the same time, this enables a lamp to be switched on without flicker with a voltage across the lamp that is lower than what is required when pre-heating is not used.
  • the requirements set on electronic ballasts regarding the heating of cathodes during the ignition of a lamp are set forth in the International standard IEC 929.
  • Fig. 2 of the drawings depicts one preferred embodiment for heating of the cathodes of a lamp LL.
  • a coil L2 includes two secondary windings for supplying the cathodes of the lamp LL with filament heating energy of a desired magnitude via capacitors C5 and C6.
  • Circuit elements R4 and V5 are used for a measuring purpose in a manner explained in more detail in connection with the description of the characterizing features of the invention.
  • the power delivered by the half-bridge connected transistor circuit TR1 and TR2 to the lamp load LL consists of two components: an actual lamp power, which sustains a light-generating discharge within the lamp, and a filament power, which is used for heating the lamp cathodes.
  • the power of cathode heating constitutes a substantial share of the power of the entire circuit.
  • a problem with the above-described ballast is the measurement of a load power in such a fashion that the actual lamp power can be measured at a sufficient accuracy without the power required by cathode heating having a significant effect on the measuring result.
  • An object of this invention is to introduce a measuring circuit connection for a ballast of the type defined in the preamble of claim 1, whereby the power of a low-pressure discharge lamp, especially a fluorescent lamp, can be measured such that the proportion of a power used for incandescence of the cathodes is compensated out of the measuring result.
  • the load circuit is constituted by a coil or winding L2, a lamp LL, and capacitors C2, C3.
  • the lamp LL is the only one of these to use effective power.
  • the energy spent by the lamp LL is divided into the use of energy caused by the lamp discharge and the energy consumed by filaments. In terms of light output, the energy of a lamp current is interesting.
  • the regulation functions well as long as the lamp power exceeds the filament power.
  • the regulation becomes inaccurate. Depending on the type of lamp, this occurs between about 10...20 % light level.
  • the effect of the filament power must be eliminated from the measuring signal. This can be effected e.g. by measuring a voltage existing across one of the cathodes of the lamp LL.
  • the cathode voltage is a product of the cathode resistance and the square sum of a filament current as well as a lamp current.
  • the filament current and the lamp current have a phase difference of about 90 degrees.
  • the filament voltage is constituted primarily by the filament current, as the lamp current is low.
  • a preferred compensating signal is obtained by simply subtracting an appropriately dimensioned voltage proportional to the filament voltage from a voltage proportional to the halfbridge supply current.
  • the compensation is dimensioned to be significant at lower light levels only.
  • the filament power can be calibrated, i.e. the effect of filament resistance fluctuations between various individual lamps can be compensated for prior to the ignition of a lamp by comparing the halfbridge current with the filament voltage.
  • a measurement from the end of a lamp yields both the filament and lamp current.
  • the dynamic impedance of a fluorescent lamp is almost resistive over a wide frequency range and the value of impedance is keenly dependent on the level of a lamp current such that, on low currents, the effective resistance is very high and, on high currents, it is respectively low.
  • Fig. 3 of the drawings illustrates one embodiment of the above-described measuring principle.
  • the total output of a load circuit is measured by using a resistance R2, which produces a voltage proportional to the current of a halfbridge TR1 - TR2, said voltage bing filtered by means of elements R3 and C4 and forwarded to an oscillator block A1.
  • the oscillator block A1 in terms of its function, is divided in two sections, whereby a sub-block II handles the processing of measuring signals and a sub-block I the control of the halfbridge transistors TR1 and TR2.
  • the voltage proportional to a power used for the heating of the cathodes of the lamp LL is developed by means of elements V4 and R1 and this measuring signal is likewise forwarded into the sub-block II of the oscillator circuit A1.
  • the difference between said measuring signals is obtained here, whereby the control block has at its disposal a real measuring signal proportional to the lamp power.
  • the control block II is able to conduct its control function in such a manner that control of the halfbridge TR1 - TR2 by way of the sub-block I guarantees a stable lighting regulation as designed for the ballast.
  • the voltage proportional to the filament power of the cathodes is obtained across a resistance R4 and the measuring signal is delivered to the control block by way of a diode V5.
  • the invention is not limited solely to the described embodiments but it equally well adaptable to numerous other frequency-regulation based ballast circuits, e.g. to multiple-lamp ballast versions.
  • the technology of switching transistors used in the halfbridge bears no significance on the usefulness of the described circuit, i.e. applicable in this context are a.o. a bipolar transistor and various versions of field effect transistors.
  • the control signal of the oscillator A1 in the circuit CO1 - CO2 can also be digital, in which case the sub-block II includes necessary circuit elements for processing digital information, e.g. by means of a programmable microcontroller.

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  • Circuit Arrangements For Discharge Lamps (AREA)
EP97660148A 1997-01-03 1997-12-19 Elektronisches Vorschaltgerät mit Helligkeitssteuerung und Messung der Lampenleistung Withdrawn EP0853445A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI970017 1997-01-03
FI970017A FI101187B (fi) 1997-01-03 1997-01-03 Lampputehon mittauksella varustettu säädettävä elektroninen liitäntäla ite

Publications (1)

Publication Number Publication Date
EP0853445A1 true EP0853445A1 (de) 1998-07-15

Family

ID=8547417

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97660148A Withdrawn EP0853445A1 (de) 1997-01-03 1997-12-19 Elektronisches Vorschaltgerät mit Helligkeitssteuerung und Messung der Lampenleistung

Country Status (2)

Country Link
EP (1) EP0853445A1 (de)
FI (1) FI101187B (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110761262B (zh) * 2019-10-14 2020-09-11 浙江大学 一种自供能的高铁路基监测系统及监测方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0422255A1 (de) * 1989-10-09 1991-04-17 Siemens Aktiengesellschaft Elektronisches Vorschaltgerät
EP0461441A1 (de) * 1990-06-06 1991-12-18 Zumtobel Aktiengesellschaft Verfahren und Schaltungsanordnung zur Regelung der Helligkeit (Dimmen) von Gasentladungslampen
US5424611A (en) * 1993-12-22 1995-06-13 At&T Corp. Method for pre-heating a gas-discharge lamp
EP0707438A2 (de) * 1994-10-13 1996-04-17 Tridonic Bauelemente GmbH Vorschaltgerät für mindestens eine Gasentladungslampe
WO1997001945A1 (en) * 1995-06-29 1997-01-16 Philips Electronics N.V. Circuit arrangement
US5612595A (en) * 1995-09-13 1997-03-18 C-P-M Lighting, Inc. Electronic dimming ballast current sensing scheme

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0422255A1 (de) * 1989-10-09 1991-04-17 Siemens Aktiengesellschaft Elektronisches Vorschaltgerät
EP0461441A1 (de) * 1990-06-06 1991-12-18 Zumtobel Aktiengesellschaft Verfahren und Schaltungsanordnung zur Regelung der Helligkeit (Dimmen) von Gasentladungslampen
US5424611A (en) * 1993-12-22 1995-06-13 At&T Corp. Method for pre-heating a gas-discharge lamp
EP0707438A2 (de) * 1994-10-13 1996-04-17 Tridonic Bauelemente GmbH Vorschaltgerät für mindestens eine Gasentladungslampe
WO1997001945A1 (en) * 1995-06-29 1997-01-16 Philips Electronics N.V. Circuit arrangement
US5612595A (en) * 1995-09-13 1997-03-18 C-P-M Lighting, Inc. Electronic dimming ballast current sensing scheme

Also Published As

Publication number Publication date
FI970017A0 (fi) 1997-01-03
FI101187B1 (fi) 1998-04-30
FI101187B (fi) 1998-04-30

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