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
  • H05B41/2828—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 control circuits for the switching elements
• • 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
  • H05B41/298—Arrangements for protecting lamps or circuits against abnormal operating conditions
  • H05B41/2988—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the lamp against abnormal operating conditions

Definitions

• the present invention relates to a circuit arrangement for operating a gas discharge lamp, in particular a low-pressure discharge lamp, according to the preamble of claim 1.
• the electronic ballast should enable reliable and effective lamp operation
• the ballast and the lamp should not interfere with other submissions in their function or have an impact on the environment.
• gas charge lamps are usually operated at high frequencies in a range from 20 to 50 kHz. At these frequencies, the electron density in the plasma of the fluorescent lamp can no longer follow the time course of the current, so that an average electron density that is essentially constant over time is established. In this case, there is no current gap until the lamp is re-ignited at zero crossing of the mains supply, so that compared to lamp operation at the usual mains frequency of 50 Hz with a constant luminous flux, a reduction in the electrical power consumed by 8 to 10% can be achieved.
• the high-frequency operation of the lamp creates high-frequency alternating fields, in which an impact on the environment cannot be completely ruled out.
• these alternating fields could lead to complaints from people nearby, for example headaches or the like.
• measures must be taken to limit the radiated field strength.
• a circuit arrangement which on the one hand implements high-frequency lamp operation and on the other hand generates high-frequency alternating fields to a relatively limited extent is described in WO 86/04752.
• the lamp is arranged in a full-bridge circuit comprising four controllable switches and controlled in such a way that two diagonally opposite switches are opened in a first operating phase, while one of the two switches of the second bridge diagonal is permanently closed and the other is clocked at high frequency. During this time, the lamp flows through the lamp essentially in the same direction.
• the four switches are activated after a while in a second operating phase in such a way that the two previously permanently open switches are closed or clocked at high frequency, while both of the other switches are now open , which effectively corresponds to a polarity reversal of the lamp.
• the lamp is operated with a low-frequency voltage signal, which is superimposed with a high-frequency oscillation.
• the amplitude of the high-frequency oscillation is relatively small, high-frequency alternating fields are only generated and emitted to a relatively small extent.
• the lamp is operated with a full-bridge circuit in such a way that, in normal operation, a switch is made between the two bridge diagonals at a first frequency, the switches of the one bridge diagonal being opened and the switches of the other bridge diagonal being closed or with a second frequency, which is greater than the first frequency.
• the gas discharge lamp is operated in normal operation with a voltage signal, which is composed of a first low-frequency signal with a relatively high amplitude and a second high-frequency signal with a low amplitude.
• the lamp is thus operated with an AC voltage for starting, the amplitude of which is greater than the amplitude of the low-frequency voltage signal in normal operation and the frequency of which is less than or equal to the second high frequency.
• the lamp is operated for a short time with a strong high-frequency signal, while after ignition it is driven with a low-frequency switched DC voltage, which is only superimposed by the high frequency. In this way, a significantly better and gentler lamp start is achieved.
• the high-frequency signal is correspondingly superimposed on the lamp direct current.
• the periodic switching of the lamp current with a low frequency ensures that the electrodes wear out uniformly and that there is no uneven coloring or blackening of the lamps at one end.
• the clock scheme according to the invention is particularly suitable for a lamp start in the megahertz range. Due to the high ignitability, it is even possible to dispense with preheating the lamp electrodes and instead start the lamp cold immediately. This in turn means that a relatively simple circuit structure can be implemented. If lamp operation in the megahertz range is actually selected, there is a further advantage that the capacitance and inductance values of some of the components used in the circuit arrangement can be reduced in such a way that integration of these is possible instead of using discrete components.
• passive components such as chokes and capacitors, which can be part of a series resonant circuit arranged in the bridge branch, for example, or transformers are suitable for integration, so that a significant reduction in the dimensions of the entire circuit can be achieved.
• the components can be integrated, for example, as part of a multi-layer circuit board circuit.
• the multilayer circuit is preferably implemented by an LTCC (Low Temperature Cofired Ceramic) structure, which consists of a plurality of low-sintered ceramic layers or foils arranged one above the other, between which there are conductor tracks, capacitive dielectric layers or the like.
• LTCC Low Temperature Cofired Ceramic
• FIG. 1 shows a ballast with a circuit arrangement according to the invention
• Fig. 3 shows the idealized time course of the voltage applied to the lamp.
• the input connected to the AC line voltage u , of the ballast shown in FIG. 1 is a rectifier circuit 1, for example a bridge rectifier or the like.
• a rectifier circuit for example a bridge rectifier or the like.
• the full bridge circuit comprises four controllable switches S1 to S4, which are formed, for example, by MOS field-effect transistors.
• the gas discharge lamp LA which is in particular a low-pressure discharge lamp, is located in the bridge branch between the center taps of the two half-bridges. Furthermore, a series resonance circuit comprising a choke coil L and a resonance capacitor Cl is arranged in the bridge branch, the low-pressure discharge lamp LA and the resonance capacitor C1 are connected in parallel.
• the four switches S1 to S4 are activated by a control circuit (not shown).
• the circuit arrangement shown in FIG. 1 can be supplemented in a known manner by monitoring circuits which detect lamp operating parameters - for example the lamp voltage and the lamp current - and influence the activation of the switches or the lamp as a function thereof. It would also be possible to detect lamp defects or the like. However, such circuit expansions are not the subject of the present invention and should therefore not be considered further.
• the frequency f3 is preferably above 1 MHz, particularly advantageously in the range between 2.2 MHz and 3.0 MHz. Since gas discharge lamps are extremely ignitable at these frequencies, the electrodes of the lamp LA may not need to be preheated. However, it can be advantageous if the frequency f3 of the clock signal for the switches S1 and S2 for starting the lamp LA is lowered in the direction of the resonance frequency of the series resonance circuit.
• the four switches S1 to S4 are activated in normal operation.
• T the two switches S2 and S3 of the one bridge diagonal are permanently opened, while the switch S1 is permanently closed and the switch S4 is clocked at high frequency.
• the switching frequency f2 for the switch S4 is preferably between 2.2 MHz and 3.0 MHz, for example approximately 2.65 MHz, and is the same as or higher than the frequency f3.
• T 2 the control circuit then changes to a second state T 2 , in which the two switches S1 and S4 of the previously clocked bridge diagonal are now opened, while switch S3 is now closed and switch S2 is also clocked at high frequency f2.
• the Switching between the two states T and T 2 takes place at a very low frequency f 1.
• the lamp voltage U ⁇ applied to the lamp LA is also shown in FIG. 3.
• the high frequency f2 is preferably in the megahertz range, while the switching frequency fl can be, for example, 50 Hz and even significantly less - up to a few mHz.
• the switching frequency fl can be, for example, 50 Hz and even significantly less - up to a few mHz.
• Uj is lower than the ignition voltage U 3 .
• the high-frequency signal components for the environmental compatibility of the lamp ballast system must be observed in the first place, a health impairment can be excluded. Otherwise, the starting phase T is only very short, so that the cause of complaints can also be excluded here.
• chokes and capacitors with relatively low capacitance and inductance values can be used for the series resonant circuit.
• Such multilayer circuits which consist of a plurality of low-sintering ceramic layers arranged one above the other, are already being used in a wide range.
• this represents a particularly advantageous embodiment since in this case the dimensions of the switching arrangement or of the entire ballast can be significantly reduced, which in turn has the consequence that further shielding devices can be attached to the ballast without great effort.

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• Circuit Arrangements For Discharge Lamps (AREA)
• Spectrometry And Color Measurement (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=7934691

Family Applications (1)

Country Status (6)

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• 1999
  • 1999-12-27 DE DE19963289A patent/DE19963289A1/de not_active Ceased
• 2000
  • 2000-10-26 EP EP00974462A patent/EP1243165B1/fr not_active Expired - Lifetime
  • 2000-10-26 DE DE50003045T patent/DE50003045D1/de not_active Expired - Lifetime
  • 2000-10-26 WO PCT/EP2000/010557 patent/WO2001049082A1/fr active IP Right Grant
  • 2000-10-26 AU AU12758/01A patent/AU1275801A/en not_active Abandoned
  • 2000-10-26 AT AT00974462T patent/ATE245887T1/de active
• 2002
  • 2002-06-26 US US10/179,176 patent/US6747423B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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