WO2007049205A2 - Method and circuit for driving gas discharge lamps using a single inverter - Google Patents
Method and circuit for driving gas discharge lamps using a single inverter Download PDFInfo
- Publication number
- WO2007049205A2 WO2007049205A2 PCT/IB2006/053870 IB2006053870W WO2007049205A2 WO 2007049205 A2 WO2007049205 A2 WO 2007049205A2 IB 2006053870 W IB2006053870 W IB 2006053870W WO 2007049205 A2 WO2007049205 A2 WO 2007049205A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- lamp
- voltage
- response characteristic
- lamps
- conducting
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims description 8
- 230000000087 stabilizing effect Effects 0.000 claims abstract description 13
- 238000001914 filtration Methods 0.000 claims abstract 3
- 230000001419 dependent effect Effects 0.000 claims description 3
- 239000003990 capacitor Substances 0.000 description 15
- 238000010586 diagram Methods 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 238000001429 visible spectrum Methods 0.000 description 1
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
- H05B41/2825—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 by means of a bridge converter in the final stage
- H05B41/2827—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 by means of a bridge converter in the final stage using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
-
- 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
-
- 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
- H05B41/24—Circuit arrangements in which the lamp is fed by high frequency ac, or with separate oscillator frequency
-
- 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
-
- 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
Definitions
- the invention relates to a method for driving gas discharge lamps as described in the preamble of claim 1.
- the invention also relates to a circuit for driving gas discharge lamps as described in the preamble of claim 4.
- US 6023131 discloses a backlight device for a liquid crystal display (LCD), which comprises a high-voltage generating means, whose output can be controlled.
- the high- voltage generating means comprises an inverter for generating an alternating output voltage.
- the output of the inverter is connected to first electrodes of three gas discharge lamps, which can emit red, green and blue light, respectively.
- a second electrode of each lamp is connected to a ground voltage line via a separate first electronic switch.
- the inverter is connected to a high- voltage source via a second electronic switch.
- a control circuit is connected to the switches to let them conduct or to block. Only when the second switch is conducting the high voltage is supplied to the inverter, so that it will generate the alternating voltage.
- the three first switches are controlled such that only one first switch is conducting at a time. There is an off- interval of not conducting of all first switches between on-times of different first switches being conducting. Only the selected one lamp will emit light.
- each lamp may emit light during a small part, in particular less than one third, of time only. Therefore, to obtain a certain amount of light during some time on average a relatively high peak current must flow through the lamps. Therefore also, the inverter, the switches and the lamps must be suitable to handle such high peak currents, which causes them to be relatively bulky and expensive.
- An object of the invention is to solve the drawbacks of the prior art method and circuit as described above.
- each lamp can be controlled to emit light or not individually for all of the time, and in practice from 1% to 100% of the time. Therefore, peak intensities and peak currents may be lower than before for obtaining the same average intensity during some time, so that the circuit and the lamps need to be less powerful and less expensive.
- Fig. 1 shows a circuit diagram of an embodiment of a ballast for three gas discharge lamps according to the invention.
- Fig. 2 shows the circuit diagram of Fig. 1 supplemented by over- voltage protection means.
- the circuit diagram shown in figure 1 represents a ballast for three gas discharge lamps 2a, 2b and 2c (indicated in general by 2).
- the lamps 2 may be suitable to emit light of the same or of different parts of the visible spectrum, such as a red, green and blue spectrum parts.
- the spectrum parts are chosen such that, dependent on control of light emissions by the lamps 2, a suitable part (a color gamut) of the chromaticity diagram as defined by the CIE (Commission Internationale de l'Eclairage) is covered.
- Control of light emission by a gas discharge lamp 2 may be carried out by changing a magnitude of an alternating lamp current through the lamp 2, changing a frequency of the alternating lamp current, possibly by changing a duty cycle of a substantial rectangular voltage.
- Each lamp 2 (2a, 2b, 2c) has a first electrode 4 (4a, 4b, 4c, respectively) and a second electrode 6 (6a, 6b, 6c, respectively).
- the electrodes 4 and 6 may be of a type which are heated by heating means to promote ignition of the lamps 2. For simplicity of the drawings and the description such heating means are not shown and are not described in detail in here.
- the circuit of Fig. 1 further comprises an inverter controller 10, a frequency controller 12, a voltage sense circuit 14, a power controller 16, a half-bridge inverter output stage consisting of electronic switches, in particular MOSFET's, 18 and 20 in series between high- voltage lines V+ and V-, a resonant or tank circuit consisting of an inductor 22 and a capacitor 24 in series between a connection node of said bridge switches 18, 20 and the V- line, and for each lamp 2 (2a, 2b, 2c) in series between its second electrode 6 (6a, 6b, 6c, respectively) and the V- line a stabilizing capacitor 26 (26a, 26b, 26c, respectively) and an electronic switch, in particular a MOSFET, 28 (28a, 28b, 28c, respectively).
- inverter controller 10 a frequency controller 12, a voltage sense circuit 14, a power controller 16, a half-bridge inverter output stage consisting of electronic switches, in particular MOSFET's, 18 and 20 in series between high- voltage lines V+ and
- the frequency controller 12 compares a reference voltage (not shown) with a voltage received from the voltage sense circuit 14 to provide an error voltage.
- the frequency controller comprises a voltage controlled oscillator (VCO, not shown) which generates a rectangular voltage of which the frequency is dependent on said error signal. Said rectangular voltage is supplied to the inverter controller 10.
- the inverter controller 10 comprises level shifters (not shown) to supply complementary control signals to control inputs (gates) of the half-bridge switches 18 and 20, so that they are switched on and off alternately and a rectangular high voltage is generated at the connection node of said switches 18 and 20 and inductor 22.
- the resonant circuit of inductor 22 and capacitor 24 is designed to resonate on a resonance frequency which is basically the same as the frequency of the rectangular voltage at the connection node of the half-bridge switches 18 and 20. As a result, a basically sinusoidal voltage will be generated at the connection node of inductor 18 and capacitor 24 of the resonant circuit.
- the power controller 16 is connected to control inputs (gates) of the electronic switches 28, called lamp switch hereinafter.
- the power controller 16 may receive data from some exterior data source (not shown) by which the power controller may control the lamp switches 28. If a lamp switch 28 is conducting an alternating current may flow through the lamp 2 connected in series with that lamp switch 28. By providing appropriate data to the power controller 16 and, accordingly, appropriate pulse widths of control signals to the lamp switches 28 any light color within the gamut of the lamps 2 can be obtained.
- the power controller 16 may control the lamp switches 28a, 28b, 28c to conduct or to block individually, that is, to conduct or to block at any time and at the same time with other ones of the lamp switches 28. That poses a problem for controlling the light intensities (or lamp power) provided by the lamps 2 as will be explained now.
- a gas discharge lamp 2 almost behaves like a constant voltage source, that is, a lamp voltage (across the lamp only) is almost constant.
- a lamp voltage (across the lamp only) is almost constant.
- a current trough a lamp 2 can be changed by changing the impedance of the capacitor 26 in series with the lamp 2, that is, by changing the frequency of the current.
- said frequency applies for all series circuits of a lamp 2 and a capacitor 26. Therefore, controlling the frequency for keeping a current through one lamp 2 constant will influence a current through an other lamp 2, so that a voltage across the series circuits changes, the frequency is changed to keep the current in said other lamp 2 constant, with the result that the current through the first mentioned lamp 2 changes, which needs control to keep it constant, and so on, so that the control of lamp currents may become unstable and light flicker may occur.
- a filter having an impedance and response characteristic which are identical (in theory) to the impedance and response characteristic provided by a lamp 2 and the stabilizing capacitor 26 in series therewith.
- C30 is the value of capacitor 30
- R32 is the value of resistor 32
- C 2 6 is the value of a stabilizing capacitor 26, and Riamp is the resistance value of a lamp 2 on average when conducting.
- a node thereof With such a filter 30, 32, a node thereof will have a voltage which is proportional to a voltage at a node of a series circuit of a lamp 2 and a capacitor 26 for all values of the frequency of the current supplied to the lamps 2.
- the impedance of the capacitors 26 changes, so that a voltage across the series circuits of a lamp 2 and a capacitor 26 and the filter 30, 32 changes.
- the voltage sense circuit 14 is supplied with an alternating voltage appearing at the node of capacitor 30 and resistor 32 of the filter.
- the voltage sense circuit 14 determines a value of a property of said voltage, such as a root mean square (RMS) value, which can be used as feed back signal value in control loop, comprising the frequency controller 12 also, to control the power of the lamps 2.
- a value of a property of said voltage such as a root mean square (RMS) value
- RMS root mean square
- the lamps of a lighting system such as a backlight device
- lamps of the same type may have a resistance value distribution of up to +/- 10%.
- Such a variation may be compensated for by inserting a resistor in series with the lamp and possibly by adjusting such resistor to meet the above condition (1).
- applying the mean value of said distribution will be suitable to meet the above condition (1) and to achieve the wanted frequency and power compensations without using an additional component in series with each lamp.
- the high DC input voltage (V+ minus V-) may be 300V; - the voltage at the first electrodes 4 of the lamps 2 may be 400Vrms;
- the frequency of the lamp current may be 20 to 200 kHz;
- control signal to a lamp switch 28 may have a repetition frequency of 75 to 150 Hz.
- Fig. 2 shows a diagram of a preferred embodiment of the circuit according to the invention.
- the circuit of Fig. 2 is supplemented with respect to the diagram shown in Fig. 1 by the addition of over- voltage protection means to protect the lamp switches 28.
- the over- voltage protection means comprises for each lamp 2 (2a, 2b, 2c) a diode 36 (36a, 36b, 36c, respectively).
- the lamp switch 28 being a MOSFET
- said diode 36 is connected to a drain of the lamp switch 28 and to one of the high voltage DC lines.
- the anode of diode 36 is connected to the drain of the lamp switch 28 and the cathode of the diode 36 is connected to the V+ line.
- the over-voltage protection means comprises for each lamp switch 28 (28a, 28b, 28c) a resistor 38 (38a, 38b, 38c, respectively), which is connected in parallel to the corresponding diode 36 (36a, 36b, 36c, respectively).
- the resistors 38 keep the drain voltage of the lamp switches 28 near the high DC voltage at line V+. In this way the parasitic drain-source capacitance of the MOSFET switches 28 is minimized.
- a resistor 38 may have a high value of, for example 100 kOhm to 1 Mohm.
- the over-voltage protection means may comprise also a zener diode (not shown) which is connected in series with said diode 36.
- a zener diode (not shown) which is connected in series with said diode 36.
- the cathode of said zener diode would be connected to the cathode of the diode 36
- a single zener diode can be used for all lamp switches 28. In this way a threshold of the drain voltage of a MOSFET lamp switch 28 above which a high frequency current is diverted from flowing through the MOSFET to flow through the diode 36 connected with the MOSFET and the zener diode is increased to the voltage of the V+ line plus the zenervoltage of the zener diode.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP06821201A EP1943884A2 (en) | 2005-10-26 | 2006-10-20 | Method and circuit for driving gas discharge lamps using a single inverter |
JP2008537267A JP2009514155A (en) | 2005-10-26 | 2006-10-20 | Method and circuit for driving multiple gas discharge lamps using a single inverter |
US12/091,113 US7733036B2 (en) | 2005-10-26 | 2006-10-20 | Method and circuit for driving gas discharge lamps using a single inverter |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP05109989.3 | 2005-10-26 | ||
EP05109989 | 2005-10-26 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2007049205A2 true WO2007049205A2 (en) | 2007-05-03 |
WO2007049205A3 WO2007049205A3 (en) | 2007-07-19 |
Family
ID=37761665
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2006/053870 WO2007049205A2 (en) | 2005-10-26 | 2006-10-20 | Method and circuit for driving gas discharge lamps using a single inverter |
Country Status (7)
Country | Link |
---|---|
US (1) | US7733036B2 (en) |
EP (1) | EP1943884A2 (en) |
JP (1) | JP2009514155A (en) |
KR (1) | KR20080067358A (en) |
CN (1) | CN101297607A (en) |
TW (1) | TW200740301A (en) |
WO (1) | WO2007049205A2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8018700B2 (en) * | 2007-08-27 | 2011-09-13 | General Electric Company | Risk of shock protection circuit |
US8994354B2 (en) * | 2013-03-11 | 2015-03-31 | Cooper Technologies Company | Electronic power converter with ground referenced lossless current sensing |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004072733A2 (en) * | 2003-02-06 | 2004-08-26 | Ceyx Technologies, Inc. | Digital control system for lcd backlights |
US20040189216A1 (en) * | 2003-03-26 | 2004-09-30 | Hwangsoo Choi | Shorted lamp detection in backlight system |
US20050012466A1 (en) * | 2003-07-16 | 2005-01-20 | Mender Chen | Multi-lamp actuating facility |
US20050116662A1 (en) * | 2003-11-06 | 2005-06-02 | Ceyx Technologies, Inc. | Method and apparatus for optimizing power efficiency in light emitting device arrays |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5402043A (en) * | 1978-03-20 | 1995-03-28 | Nilssen; Ole K. | Controlled driven series-resonant ballast |
US5173643A (en) * | 1990-06-25 | 1992-12-22 | Lutron Electronics Co., Inc. | Circuit for dimming compact fluorescent lamps |
BE1009331A3 (en) | 1995-04-20 | 1997-02-04 | Vito | Power circuit for discharge lamps. |
JP3486742B2 (en) * | 1997-11-27 | 2004-01-13 | 株式会社ヒューネット | Backlight for LCD display |
CN2394401Y (en) * | 1999-10-25 | 2000-08-30 | 俞志龙 | High power factor electronic ballast with low current peak-to-valley rate |
US6954036B2 (en) * | 2003-03-19 | 2005-10-11 | Moisin Mihail S | Circuit having global feedback for promoting linear operation |
JP2005078910A (en) * | 2003-08-29 | 2005-03-24 | Mitsubishi Electric Corp | High luminance discharge lamp lighting device |
MXPA04012080A (en) | 2003-12-03 | 2005-07-01 | Universal Lighting Tech Inc | Lossless circuit for sampling of lamp voltage. |
-
2006
- 2006-10-20 WO PCT/IB2006/053870 patent/WO2007049205A2/en active Application Filing
- 2006-10-20 CN CNA2006800398135A patent/CN101297607A/en active Pending
- 2006-10-20 KR KR1020087012444A patent/KR20080067358A/en not_active Application Discontinuation
- 2006-10-20 EP EP06821201A patent/EP1943884A2/en not_active Withdrawn
- 2006-10-20 JP JP2008537267A patent/JP2009514155A/en not_active Abandoned
- 2006-10-20 US US12/091,113 patent/US7733036B2/en not_active Expired - Fee Related
- 2006-10-23 TW TW095139075A patent/TW200740301A/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004072733A2 (en) * | 2003-02-06 | 2004-08-26 | Ceyx Technologies, Inc. | Digital control system for lcd backlights |
US20040189216A1 (en) * | 2003-03-26 | 2004-09-30 | Hwangsoo Choi | Shorted lamp detection in backlight system |
US20050012466A1 (en) * | 2003-07-16 | 2005-01-20 | Mender Chen | Multi-lamp actuating facility |
US20050116662A1 (en) * | 2003-11-06 | 2005-06-02 | Ceyx Technologies, Inc. | Method and apparatus for optimizing power efficiency in light emitting device arrays |
Also Published As
Publication number | Publication date |
---|---|
US7733036B2 (en) | 2010-06-08 |
EP1943884A2 (en) | 2008-07-16 |
CN101297607A (en) | 2008-10-29 |
US20080252227A1 (en) | 2008-10-16 |
WO2007049205A3 (en) | 2007-07-19 |
TW200740301A (en) | 2007-10-16 |
JP2009514155A (en) | 2009-04-02 |
KR20080067358A (en) | 2008-07-18 |
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