EP0848581A1 - Circuit de chauffage des cathodes d'une lampe à décharge basse-pression - Google Patents
Circuit de chauffage des cathodes d'une lampe à décharge basse-pression Download PDFInfo
- Publication number
- EP0848581A1 EP0848581A1 EP97660141A EP97660141A EP0848581A1 EP 0848581 A1 EP0848581 A1 EP 0848581A1 EP 97660141 A EP97660141 A EP 97660141A EP 97660141 A EP97660141 A EP 97660141A EP 0848581 A1 EP0848581 A1 EP 0848581A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- circuit
- lamp
- filament
- capacitor
- series
- 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- Withdrawn
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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
- H05B41/295—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
Definitions
- the present invention relates to a cathode filament heating circuit for a low-pressure discharge lamp, whereby the power used for heating can be regulated to a level required by any given operating condition of the lamp.
- Heating of the cathodes of a lamp has an adverse effect on the energy efficiency of the assembly consisting of a lamp and a ballast as the heating of cathodes consumes energy.
- this aspect has not been considered especially important, since the electronic ballasts operating at a high frequency have had a significant advantage over magnetic ballasts in terms of energy efficiency.
- it has become necessary to improve the efficiency of electronic ballasts in an effort to achieve a better saving of energy for cutting down the equipment restitution time.
- An object of this invention is a filament circuit for a low-pressure discharge lamp, especially a fluorescent lamp, whereby the power used for incandescence can be regulated as required by the operating condition of a lamp for improving the energy efficiency but without jeopardizing the favourable operating conditions of a lamp.
- the prior art is represented by an electronic ballast circuit shown in fig. 1.
- the electric power delivered from a rectifier 1 is used for driving a high-frequency oscillator 2, the high-frequency alternating current supplied thereby passing through a series circuit constituted by a winding 4, a capacitor 5, and a lamp 3.
- Parallel to the lamp 3 in series with electrodes 6 and 7 is connected a series circuit constituted by a temperature-dependent resistance 9 and a capacitor 8.
- An advantage offered by the above-described circuit is the optimal behaviour of cathode heating during and after the switch-on sequence of a lamp. After the switch-on sequence of a lamp, upon assuming a normal burning condition, the filament current decreases whereby the power consumption of the circuit decreases to improve the efficiency of an entire ballast.
- fig. 2 basically illustrates the behaviour of a cathode current and a lamp voltage starting from the switch-on moment.
- a problem with such a circuit is that the temperature-dependent resistance will have such a high voltage load that setting up the circuit requires the use of special components. This naturally increases the implementation costs of a circuit.
- Patent publication EP 185179 as well as the works “Betriebsowski und Druckmaschine fuerloise Lampen”, (C.H. Sturm & E. Klein, Siemens AG, 1992, page 131) and "Application Report: Electronic Ballasts for Fluorescent Lamps using BUL770/791 Transistors", (Texas Instruments, 1992, p. 9) disclose a solution, wherein parallel to a voltage-dependent resistance is connected a capacitor to achieve a significant reduction in the voltage stress of said resistance.
- This circuit configuration is depicted in fig. 3 and the basic behaviour of the cathode current of a lamp as well as the lamp voltage is shown in fig. 4.
- a drawback with this circuit is that, after the switch-on moment, the filament current increases along with the lamp voltage and, after the lamp has been switched on, it remains at a reasonably high level resulting in unnecessary consumption of power and, thus, decreases the efficiency of a ballast.
- incandescence does not work if one of the lamp cathodes is broken as these are connected in series with the filament circuit and in this situation the ignition of the lamp is impossible.
- the Applicant's patent FI-95527 discloses a circuit arrangement, wherein a series circuit constituted by one of the electrodes of a lamp and a positive temperature-coefficient dependent resistance is connected in parallel with the lamp, and in parallel with a series circuit constituted by the other electrode of the lamp and said resistance is connected a capacitor, as shown in fig. 5.
- the filament current of a cathode 6 decreases substantially after the switch-on sequence, which brings down the consumption of power by the cathode and in the voltage-dependent resistance.
- the reduced power loss improves the efficiency of a ballast and increases the service life of a voltage-dependent resistance since, in principle, said component ages along with the passage of service time.
- incandescence works even if the lamp cathode 6 is broken, enabling the ignition of a lamp in this situation as well.
- a possible problem could be that the filament circuit does not operate symmetrically relative to the lamp, which may result in the previously discussed hazard of the blackening effect for the ends of a lamp.
- a common feature for all of the above-described circuit configurations is that said circuits are based on the use of a temperature-dependent resistance.
- a major drawback with this type of component is that, in principle, the component is ageing, i.e. it has a limited service life. Furthermore, it is quite expensive and unreliable. None of the above-described circuit configurations is as such suitable for use in controllable or dimmable ballasts, since it is inevitable that the filament power of cathodes can be varied as desired according to variations of the current passing through the lamp.
- An object of the invention is to provide an improved circuit solution, whereby the filament heating level of cathodes can be varied as desired according to variations in a current passing through a lamp without having to resort to the use of a temperature-dependent resistance.
- a cathode filament circuit of the invention the filament current passing through the cathodes is regulated by the application of a resonance principle.
- a circuit arrangement according to an embodiment of the invention is depicted in fig. 7.
- the purpose of a capacitor 11 is to provide a sufficient pre-incandescence heating for cathodes during a switch-on sequence, the filament current passing primarily through a circuit constituted by said cathodes and capacitor.
- the series circuit constituted by a winding 12 and a capacitor 13 is connected in parallel with each electrode of the lamp 3, in series with the filament current capacitor 11.
- the circuit elements 12 and 13 develop a resonance circuit at a certain frequency, whereby it is possible to regulate the current passing through the cathodes by changing between poles 14 and 15 the frequency of a supply voltage operating across the lamp. With such a simple method, it is possible to reduce the filament current to a desired level after the ignition of a lamp in non-controllable or controllable ballasts, which results in a desired saving in the energy required for heating the cathodes.
- the circuit can be used in a variety of ballast designs, the only requirement being the accurate control over the frequency of a voltage to be supplied to the lamp. Said regulation of the heating is achieved in practice without expensive or unreliable circuit elements.
- Figs. 8-10 illustrate other feasible embodiments for the invention described in this patent application.
- the operating principle is always the same, but the resonance circuit is set up in a number of ways.
- the resonance circuit is completed with a winding 12', which is connected in series with a filament current capacitor 11 in parallel with a lamp.
- the resonance circuit is constituted by a series circuit, which comprises a winding 12 and a capacitor 13 and is connected in series with a filament current capacitor 11 in parallel with a lamp 3.
- the resonance circuit is constituted by a parallel circuit, which comprises a winding 12 and a capacitor 13 and is connected in series with a filament current capacitor 11 in parallel with a lamp 3.
- the filament heating current passing through cathodes is regulated by a resonance principle.
- An example of the circuit system for bringing about this function is depicted in fig. 11 of the drawing.
- the coil 4 of fig. 1 is represented by a transformer 17, consisting of a primary winding L1 and at least two secondary windings L2 and L3.
- the coil 17 and the capacitor 11 constitute a main resonance circuit for the ballast, which determines the oscillation frequency.
- the function of a capacitor 19 is the separation of a direct voltage.
- the energy required for heating cathodes 6 and 7 is received from the secondary windings L2 and L3 of the transformer 17.
- a capacitor 13 and an additional winding 12 as well as a capacitor 16 and an additional winding 18, respectively, constitute a resonance circuit at a given frequency, whereby it is possible to regulate a current passing through the cathodes by changing the frequency of a supply voltage between poles 14 and 15. In this simple manner it is possible to reduce the filament heating current to a desired level after the ignition in undimmable or dimmable ballasts. This achieves a desired saving in the energy required for heating the cathodes.
- the circuit can be used in a variety of ballast configurations, the only condition being an accurate control over the frequency of a voltage supplied to a lamp. Such filament heating regulation function can be achieved in practice without expensive or unreliable circuit elements.
- Fig. 12 of the drawing illustrates another possible embodiment for a transformer-equipped circuit.
- the operating principle is similar to that of fig. 11, but the resonance circuit is implemented without a separate coil in the cathode filament heating circuit (coils 12 and 18 in fig. 11).
- the transformer 17 is implemented in such a way that the stray inductance of its windings provides an inductance of required magnitude for creating a resonance circuit.
- the implementation costs of a circuit go down dramatically.
- a transformer-equipped circuit solution can also be implemented as depicted in fig. 13 of the drawing.
- the location of a capacitor 19 is changed in such a manner that one cathode head 15 of a lamp will be connected to the earth potential of the transistor bridge of a chopper circuit.
Landscapes
- Circuit Arrangements For Discharge Lamps (AREA)
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI964972 | 1996-12-12 | ||
FI964972A FI101033B (fi) | 1996-12-12 | 1996-12-12 | Pienipaineisen purkauslampun katodihehkutuspiiri |
FI971362 | 1997-04-03 | ||
FI971362A FI971362A0 (fi) | 1997-04-03 | 1997-04-03 | Katodglaedkrets foer en urladdningslampa med laogt tryck |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0848581A1 true EP0848581A1 (fr) | 1998-06-17 |
Family
ID=26160275
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97660141A Withdrawn EP0848581A1 (fr) | 1996-12-12 | 1997-12-10 | Circuit de chauffage des cathodes d'une lampe à décharge basse-pression |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP0848581A1 (fr) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1202612A2 (fr) * | 2000-10-30 | 2002-05-02 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Dispositif d'éclairage à préchauffage amélioré pour lampes à décharge |
WO2010070003A1 (fr) * | 2008-12-19 | 2010-06-24 | Tridonicatco Gmbh & Co.Kg | Circuit de chauffage d'un appareil de commande destiné à des lampes à décharge de gaz |
US9041293B2 (en) | 2011-12-27 | 2015-05-26 | Industrial Technology Research Institute | Lamp control system, lamp power-saving system and method therefor |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5319284A (en) * | 1993-07-30 | 1994-06-07 | Lee Sang Woo | Electronic ballast circuit for discharge lamp |
EP0602719A1 (fr) * | 1992-12-16 | 1994-06-22 | Koninklijke Philips Electronics N.V. | Onduleur haute fréquence pour alimenter une lampe à décharge munie d'électrodes de préchauffage |
DE4303595A1 (de) * | 1993-02-08 | 1994-08-11 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Schaltungsanordnung zum Betrieb einer Leuchtstofflampe |
-
1997
- 1997-12-10 EP EP97660141A patent/EP0848581A1/fr not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0602719A1 (fr) * | 1992-12-16 | 1994-06-22 | Koninklijke Philips Electronics N.V. | Onduleur haute fréquence pour alimenter une lampe à décharge munie d'électrodes de préchauffage |
DE4303595A1 (de) * | 1993-02-08 | 1994-08-11 | Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh | Schaltungsanordnung zum Betrieb einer Leuchtstofflampe |
US5319284A (en) * | 1993-07-30 | 1994-06-07 | Lee Sang Woo | Electronic ballast circuit for discharge lamp |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1202612A2 (fr) * | 2000-10-30 | 2002-05-02 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Dispositif d'éclairage à préchauffage amélioré pour lampes à décharge |
EP1202612A3 (fr) * | 2000-10-30 | 2003-11-19 | Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH | Dispositif d'éclairage à préchauffage amélioré pour lampes à décharge |
WO2010070003A1 (fr) * | 2008-12-19 | 2010-06-24 | Tridonicatco Gmbh & Co.Kg | Circuit de chauffage d'un appareil de commande destiné à des lampes à décharge de gaz |
US9041293B2 (en) | 2011-12-27 | 2015-05-26 | Industrial Technology Research Institute | Lamp control system, lamp power-saving system and method therefor |
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