EP0848580A1 - Elektronisches Vorschaltgerät mit thermischer Schutzschaltung - Google Patents

Elektronisches Vorschaltgerät mit thermischer Schutzschaltung Download PDF

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Publication number
EP0848580A1
EP0848580A1 EP97660142A EP97660142A EP0848580A1 EP 0848580 A1 EP0848580 A1 EP 0848580A1 EP 97660142 A EP97660142 A EP 97660142A EP 97660142 A EP97660142 A EP 97660142A EP 0848580 A1 EP0848580 A1 EP 0848580A1
Authority
EP
European Patent Office
Prior art keywords
lamp
ballast
circuit
voltage
safety 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.)
Granted
Application number
EP97660142A
Other languages
English (en)
French (fr)
Other versions
EP0848580B1 (de
Inventor
Harri Naakka
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
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Filing date
Publication date
Application filed by Helvar Oy AB filed Critical Helvar Oy AB
Publication of EP0848580A1 publication Critical patent/EP0848580A1/de
Application granted granted Critical
Publication of EP0848580B1 publication Critical patent/EP0848580B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H05B41/26—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
    • H05B41/282—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
    • H05B41/285—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H05B41/2851—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
    • H05B41/2856—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions against internal abnormal circuit conditions
    • 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
    • H05B41/282—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
    • H05B41/285—Arrangements for protecting lamps or circuits against abnormal operating conditions
    • H05B41/2851—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions
    • H05B41/2855—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the circuit against abnormal operating conditions against abnormal lamp operating conditions

Definitions

  • the present invention relates to a safety circuit for the electronic ballast of a low-pressure discharge lamp, especially a fluorescent lamp, intended to prevent destruction of the ballast at a high operating temperature.
  • the structure of electronic ballasts for low-pressure discharge lamps is prior known from the Applicant's patent No. FI 64487 as well as theoretical principles 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 providing a light output proportional to an external control signal.
  • the prior art is represented by a circuit for an electronic ballast set forth in the Applicant's patent No. FI 63148, a slightly simplified version of which is depicted in fig. 1.
  • a source of direct voltage which may be constituted by a rectifier connected to a source of alternating voltage
  • two transistors 1 and 2 constituting a semi-bridge.
  • One of the poles of a primary winding 4 of a transformer 3 is connected between the transistors 1 and 2 and the other pole is connected to a winding 7, which is in turn connected via a capacitor 11 to one of the electrodes of a lamp 8.
  • the transformer 3 is provided with secondary windings 5 and 6 connected to the bases of the transistors 1 and 2 so as to receive oppositely phased control voltages.
  • the other one is non-conducting and vice versa.
  • a capacitor 9 parallel to the lamp 8 in series with the lamp electrodes is a capacitor 9. The circuit is intended to supply the lamp 8 with a high-frequency current inverted from direct voltage and, furthermore, to conduct the ignition of said lamp.
  • Such conditions include e.g. a deviation of the characteristics of a discharge lamp - especially a fluorescent lamp - from the standardized values thereof.
  • Such a condition develops normally along with the ageing of a lamp as the emission material serving as a coating for the lamp cathodes gradually disappears, which has an adverse effect e.g. on the switch-on characteristics of a lamp. This effect is termed as deactivation of a lamp.
  • the ageing of a lamp has also been discovered to result in changes relating to the burning voltage of a lamp.
  • the cathodes of a discharge lamps may also break completely either as a result of ageing or structural fragility.
  • ballast is set at an operating temperature other than what is specified therefor, the result may be an excessive rise of the temperature existing within the ballast, which in the worst case may destroy electrical components or other materials of the ballast.
  • the ballast can be set in such a safe condition in which the oscillation of an oscillator is stopped.
  • This type of safe condition is often termed as a stand-by state.
  • the ballast includes a special control block intended to identify the above-described abnormal operating conditions and to change the functional state of the ballast appropriately for protecting the electronic components.
  • the circuit must be provided with elements, whereby the ballast can resume its normal functional state as the abnormal operating conditions are eliminated.
  • Fig. 2 of the drawings depicts this type of ballast design, wherein the section for the above-discussed safety circuit is indicated by a block 10.
  • This control block includes necessary electronic circuit elements for identifying said abnormal operating conditions by measuring certain electrical signals and temperature existing within the device.
  • the measurement of temperature requires some circuit element, one electrcal parameter of which is proportional to temperature in a known fashion.
  • Such components include e.g. thermistors, having a resistance which changes as a function of temperature.
  • the temperature measuring components have a problem of being usually quite expensive, the site therefor within the device is strictly confined, and some have also a limited service life (e.g. the above-discussed thermistors). It is also possible to place such a temperature-proportional circuit element outside said safety circuit block 10, e.g. in series with the mains voltage feed of a ballast whereby, upon excessive heating of the device, its current supply can be cut off.
  • An object of this invention is to provide thermal protection for the electronic mains ballast of a low-pressure discharge lamp, especially a fluorescent lamp, in a simpler and more reliable manner than what has been suggested in the prior art solutions.
  • a transformer 3 is wound around a core made of a magnetic material, e.g. ferrite.
  • a magnetic material e.g. ferrite.
  • One preferred structure is an annular transformer core or a toroid.
  • the safety circuit 10 includes circuit elements for measuring a voltage operating across a lamp. This is depicted in fig. 2 by means of a connection, wherein a measuring signal is obtained from a connection point A common to a winding 7 and one of the cathodes of a lamp 8. The other cathode of the lamp 8 is in turn connected to an earthing point (-) of a direct-voltage source.
  • the voltage across a lamp is measurable with a measuring circuit from one end of the lamp only.
  • the invention makes use of the magnetic properties of the core of said transformer 3. It is general knowledge that, with certain magnetic core materials, the highest acceptable induction density in the core becomes lower as temperatures rises, i.e. the core of a transformer saturates even with less intense magnetization. Thus, in said circuit arrangement of the invention, a transformer core, especially a toroid core, saturates with a lower winding current as temperature in the core, i.e. within a ballast, increases. Hence, the voltage of secondary windings 5 and 6, which produces a positive terminal current in switching transistors, runs out sooner. This results in an increase in the frequency of a semi-bridge oscillator circuit, which is shown in fig. 2 in the process of switching on the lamp 8.
  • the voltage visible across the lamp 8 increases, which is identified in the safety block 10 as a function of frequency and voltage.
  • the safety block 10 turns off the vibration of the oscillator circuit as the measuring value of a voltage across the lamp 8 exceeds a given predetermined threshold value.
  • the oscillator can be stopped e.g. by blocking the passage of the terminal current of transistors 1 and 2.
  • a circuit configuration appropriate for this is disclosed e.g. in Patent EP 0,146,683.
  • the ballast assumes a shielded condition, in which there are hardly any power losses and the internal temperature of the device falls to a safe level so as to protect structural components of the device from destruction.
  • a typical feature for the solution of the invention is that the measuring of temperature does not require separate circuit elements but, instead, it is possible to exploit the thermal properties of a component included integrally in the ballast assembly.
  • the safety circuit 10 shall in any case include a measuring circuit for a voltage operating across the lamp 8, since the identification of a lamp voltage upon the ageing of a lamp must be carried out anyway for reasons of safety, the thermal protection of a ballast will be handled in a highly simple, reliable, and economical manner.
  • the transformer 3 be constructed such that the saturation properties of its core change as a function of temperature in a desired fashion. This can be contributed by properly selecting the shape of the magnetic material and the magnetic circuit of a transformer core. All structural components must be such a heat resistance and the circuit elements must be arranged such that damage to the materials is avoided prior to actuating the safety circuit.
  • the solution makes use also of the frequency behaviour of the lamp voltage of low-pressure discharge lamps.

Landscapes

  • Circuit Arrangements For Discharge Lamps (AREA)
EP19970660142 1996-12-16 1997-12-11 Elektronisches Vorschaltgerät mit thermischer Schutzschaltung Expired - Lifetime EP0848580B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI965024A FI101186B (fi) 1996-12-16 1996-12-16 Lämpösuojapiirillä varustettu elektroninen liitäntälaite
FI965024 1996-12-16

Publications (2)

Publication Number Publication Date
EP0848580A1 true EP0848580A1 (de) 1998-06-17
EP0848580B1 EP0848580B1 (de) 2000-07-19

Family

ID=8547273

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19970660142 Expired - Lifetime EP0848580B1 (de) 1996-12-16 1997-12-11 Elektronisches Vorschaltgerät mit thermischer Schutzschaltung

Country Status (3)

Country Link
EP (1) EP0848580B1 (de)
DE (1) DE69702588T2 (de)
FI (1) FI101186B (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1054581A2 (de) * 1999-05-18 2000-11-22 CEE Electra S.r.l. Anordnung zum Betreiben und Steuern von elektrischen Lichtquellen
WO2006128435A2 (de) * 2005-06-01 2006-12-07 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Schaltungsanordnung zum betrieb einer entladungslampe mit temperaturausgleich
WO2009029334A2 (en) * 2007-08-27 2009-03-05 General Electric Company Thermal foldback for linear fluorescent lamp ballasts
DE102011103638A1 (de) * 2011-06-08 2012-12-13 Tridonic Gmbh & Co. Kg Verfahren zum Betreiben eines elektronischen Vorschaltgeräts für ein Leuchtmittel und elektronisches Vorschaltgerät

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4282462A (en) * 1979-10-16 1981-08-04 General Electric Company Arc lamp lighting unit with means to prevent prolonged application of starting potentials
EP0146683A1 (de) * 1981-07-31 1985-07-03 Siemens Aktiengesellschaft Wechselrichter
DE3840845A1 (de) * 1987-10-02 1990-06-07 Narva Veb Schaltungsanordnung fuer die zuendung und den betrieb einer niederdruckentladungslampe
DE4300399A1 (de) * 1993-01-09 1994-07-14 Hueco Gmbh Fabrik Fuer Elektro Schaltungsanordnung zum Betreiben einer Leuchtstofflampe im hochfrequenten Betrieb
EP0658072A2 (de) * 1993-12-06 1995-06-14 General Electric Company Vorschaltgerät für eine Entladungslampe mit vorheizbaren Wendeln

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4282462A (en) * 1979-10-16 1981-08-04 General Electric Company Arc lamp lighting unit with means to prevent prolonged application of starting potentials
EP0146683A1 (de) * 1981-07-31 1985-07-03 Siemens Aktiengesellschaft Wechselrichter
DE3840845A1 (de) * 1987-10-02 1990-06-07 Narva Veb Schaltungsanordnung fuer die zuendung und den betrieb einer niederdruckentladungslampe
DE4300399A1 (de) * 1993-01-09 1994-07-14 Hueco Gmbh Fabrik Fuer Elektro Schaltungsanordnung zum Betreiben einer Leuchtstofflampe im hochfrequenten Betrieb
EP0658072A2 (de) * 1993-12-06 1995-06-14 General Electric Company Vorschaltgerät für eine Entladungslampe mit vorheizbaren Wendeln

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1054581A2 (de) * 1999-05-18 2000-11-22 CEE Electra S.r.l. Anordnung zum Betreiben und Steuern von elektrischen Lichtquellen
EP1054581A3 (de) * 1999-05-18 2002-04-17 CEE Electra S.r.l. Anordnung zum Betreiben und Steuern von elektrischen Lichtquellen
WO2006128435A2 (de) * 2005-06-01 2006-12-07 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Schaltungsanordnung zum betrieb einer entladungslampe mit temperaturausgleich
WO2006128435A3 (de) * 2005-06-01 2007-03-29 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Schaltungsanordnung zum betrieb einer entladungslampe mit temperaturausgleich
US7911148B2 (en) 2005-06-01 2011-03-22 Osram Gesellschaft Mit Beschraenkter Haftung Circuit arrangement for operating a discharge lamp having temperature compensation
WO2009029334A2 (en) * 2007-08-27 2009-03-05 General Electric Company Thermal foldback for linear fluorescent lamp ballasts
WO2009029334A3 (en) * 2007-08-27 2009-05-14 Gen Electric Thermal foldback for linear fluorescent lamp ballasts
CN101796889A (zh) * 2007-08-27 2010-08-04 通用电气公司 线性荧光灯镇流器的热返送
US7817453B2 (en) 2007-08-27 2010-10-19 General Electric Company Thermal foldback for linear fluorescent lamp ballasts
CN101796889B (zh) * 2007-08-27 2015-01-28 通用电气公司 线性荧光灯镇流器的热返送
DE102011103638A1 (de) * 2011-06-08 2012-12-13 Tridonic Gmbh & Co. Kg Verfahren zum Betreiben eines elektronischen Vorschaltgeräts für ein Leuchtmittel und elektronisches Vorschaltgerät
EP2719259B1 (de) * 2011-06-08 2019-10-30 Tridonic GmbH & Co KG Verfahren zum betreiben eines elektronischen vorschaltgeräts für ein leuchtmittel und elektronisches vorschaltgerät

Also Published As

Publication number Publication date
FI101186B1 (fi) 1998-04-30
DE69702588T2 (de) 2001-04-19
FI965024A0 (fi) 1996-12-16
DE69702588D1 (de) 2000-08-24
EP0848580B1 (de) 2000-07-19
FI101186B (fi) 1998-04-30

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