Method and circuit arrangement for operating a discharge lamp
First Claim
1. Method for operating a discharge lamp (EL), with a load circuit which contains the discharge lamp (EL), a capacitor (C5) connected in parallel therewith, a coil (L2), at least one further capacitor (C6) and an element (R2) which registers a load current (IL) flowing in the load circuit, and with an inverter with two switching elements (T1, T2) which are externally controlled with a frequency (fInv) of the inverter, characterized in that the following procedural steps are carried outin the preheating phase (TV)registering the actual value of the load current (IL);
- forming a first, time-invariant setpoint value (SW1) of the load current (IL), which corresponds to a desired actual value of a load current in the preheating phase;
activating a clock generator (TG) which runs freely at a frequency (fTG) which is less than the resonant frequency (fres1) of the load circuit when the lamp is off and is greater than the resonant frequency (fres2) of the load circuit when the lamp is on;
terminating the preheating phase after a first predeterminable time period (TV) has elapsed;
in the striking phase (TZ)registering the actual value of the load current (IL) in the load circuit;
forming a time-varying setpoint value (SW2(t)) of the load current, which setpoint value (SW2(t)) is brought from a time-invariant setpoint value (SW1) of the load current (IL) to a predeterminable value (SW2max);
synchronizing the clock generator (TG) with the frequency (fInv) of the inverter;
terminating the striking phase as soon as the setpoint value of the load current (IL) has reached a value at which the on-time of a half-bridge switching element is greater than the period (tTG =1/fTG) of the free-running clock generator (TG),in normal operation (TN)registering the actual value of the load current (IL); and
forming a second, time-invariant setpoint value (SW5) of the load current, which setpoint value (SW5) corresponds to a desired actual value of the load current in normal operation.
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Accused Products
Abstract
The invention relates to a method and a circuit arrangement for operating aischarge lamp. In the preheating phase, the actual value of the load current is registered, a first time-invariant setpoint value of the load current, which corresponds to a desired actual value of a load current in the preheating phase, is formed, and a clock generator is activated, which runs freely at a frequency which is less than the resonant frequency of the load circuit when the lamp is off and is greater than the resonant frequency of the load circuit when the lamp is on. The preheating phase is terminated after a first predeterminable time period has elapsed. In the striking phase, the actual value of the load current in the load circuit is registered, a time-varying setpoint value of the load current is formed, and the clock generator is synchronized with the frequency of an inverter. The striking phase is terminated as soon as the setpoint value of the load current reaches a value at which an on-time of a half-bridge switching element is greater than the period of the free-running clock generator. In normal operation, the actual value of the load current is registered and a second time-invariant setpoint value of the load current is formed, which setpoint value corresponds to a desired actual value of the load current in normal operation.
44 Citations
25 Claims
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1. Method for operating a discharge lamp (EL), with a load circuit which contains the discharge lamp (EL), a capacitor (C5) connected in parallel therewith, a coil (L2), at least one further capacitor (C6) and an element (R2) which registers a load current (IL) flowing in the load circuit, and with an inverter with two switching elements (T1, T2) which are externally controlled with a frequency (fInv) of the inverter, characterized in that the following procedural steps are carried out
in the preheating phase (TV) registering the actual value of the load current (IL); -
forming a first, time-invariant setpoint value (SW1) of the load current (IL), which corresponds to a desired actual value of a load current in the preheating phase; activating a clock generator (TG) which runs freely at a frequency (fTG) which is less than the resonant frequency (fres1) of the load circuit when the lamp is off and is greater than the resonant frequency (fres2) of the load circuit when the lamp is on; terminating the preheating phase after a first predeterminable time period (TV) has elapsed; in the striking phase (TZ) registering the actual value of the load current (IL) in the load circuit; forming a time-varying setpoint value (SW2(t)) of the load current, which setpoint value (SW2(t)) is brought from a time-invariant setpoint value (SW1) of the load current (IL) to a predeterminable value (SW2max); synchronizing the clock generator (TG) with the frequency (fInv) of the inverter; terminating the striking phase as soon as the setpoint value of the load current (IL) has reached a value at which the on-time of a half-bridge switching element is greater than the period (tTG =1/fTG) of the free-running clock generator (TG), in normal operation (TN) registering the actual value of the load current (IL); and forming a second, time-invariant setpoint value (SW5) of the load current, which setpoint value (SW5) corresponds to a desired actual value of the load current in normal operation. - View Dependent Claims (2, 3)
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- 4. Method for operating a discharge lamp (EL), with a load circuit which contains the discharge lamp (EL), a capacitor (C5) connected in parallel therewith, a coil (L2), at least one further capacitor (C6) and an element (R2) which registers a load current (IL) flowing in the load circuit, and with an inverter with two switching elements (T1, T2) which are externally controlled with a frequency (fInv) of the inverter, characterized in that each individual half-period of the load current is regulated to a predeterminable setpoint value in each operating phase of the lamp, and in order to regulate the period of the load current, the actual value of the integral of the current with respect to time in a half-oscillation or a full-oscillation of the load current is registered, and this integral is compared with the setpoint value of the integral of the current with respect to time in a half-oscillation or a full oscillation of the load current in the respective current operating phase, in that when the actual and setpoint values of the load current coincide, the inverter is driven in such a way that the switching element (T2) activated at this particular time is deactivated and the switching element (T1) not activated at this particular time is activated.
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7. Circuit arrangement for operating a discharge lamp (EL), with a load circuit which contains the discharge lamp (EL), a capacitor (C5) connected in parallel therewith, a coil (L2), at least one further capacitor (C6) and an element (R2) which registers a load current (IL) flowing in the load circuit, and with an inverter with two switching elements (T1, T2) which are externally controlled with a frequency (fInv) of the inverter, the circuit arrangement comprising:
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means for registering the actual value of the load current (IL) in a preheating phase (TV); means for forming a first, time-invariant setpoint value (SW1) of the load current (IL), which corresponds to a desired actual value of a load current in the preheating phase; means for activating a clock generator (TG) which runs freely at a frequency (fTG) which is less than the resonant frequency (fres1) of the load circuit when the lamp is off and is greater than the resonant frequency (fres2) of the load circuit when the lamp is on; means for terminating the preheating phase after a first predeterminable time period (TV) has elapsed; means for registering the actual value of the load current (IL) in the load circuit in a striking phase (TZ); means for forming a time-varying setpoint value (SW2(t)) of the load current, which setpoint value (SW2(t)) is brought from a time-invariant setpoint value (SW1) of the load current (IL) to a predeterminable value (SW2max); means for synchronizing the clock generator (TG) with the frequency (fInv) of the inverter; means for terminating the striking phase as soon as the setpoint value of the load current (IL) has reached a value at which the on-time of a half-bridge switching element is greater than the period (tTG =1/fTG) of the free-running clock generator (TG); means for registering the actual value of the load current (IL) in normal operation (TN); means for forming a second, time-invariant setpoint value (SW5) of the load current, which setpoint value (SW5) corresponds to a desired actual value of the load current in normal operation. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification