EP0374617A2 - Device for starting and operating electric gas discharge lamps - Google Patents

Abstract

In a device for starting and operating electric gas discharge lamps, in particular in motor vehicles, having an alternating voltage source to which a gas discharge lamp is connected, having a transformer, the secondary winding of which is arranged in series with the gas discharge lamp and forms an oscillatory circuit with a first capacitor, and the primary winding of which is part of a firing circuit which contains a second capacitor and a semiconductor switch, having a voltage detection device in the firing circuit which is connected via a switching device to the semiconductor switch, in order to minimise the reactive load for the alternating voltage source by means of the transformer and to ensure a reliable firing and operation of the device, the first secondary winding of the transformer, the first capacitor and the gas discharge lamp form a first series oscillatory circuit, the resonant frequency of the first series oscillatory circuit corresponding to the basic frequency of the voltage of the alternating voltage source. <IMAGE>

Description

The invention relates to a device for igniting and operating electrical gas discharge lamps, in particular in motor vehicles, with an AC voltage source to which a gas discharge lamp is connected, with a transformer whose secondary winding is arranged in series with the gas discharge lamp and which forms a resonant circuit with a first capacitor and whose primary winding is part of an ignition circuit, which contains a second capacitor and a semiconductor switch, with a voltage detection device in the ignition circuit, which is connected to the semiconductor switch via a switching device.

From the German patent DE-PS 15 89 306 a device for igniting and operating electrical gas discharge lamps, in particular those with ignition voltages of more than 1000 volts, is known. Here, an AC voltage source is electrically conductively connected to a gas discharge lamp via a series choke and the secondary winding of a transformer. A first capacitor is arranged in parallel with the series circuit comprising the secondary winding of the transformer and the gas discharge lamp and forms an oscillating circuit with the latter. The primary winding of the transformer is part of an ignition circuit. The ignition circuit consists of the primary winding, a choke, a semiconductor switch and a second capacitor. The ignition circuit is assigned a voltage detection device which, for. B. from a voltage divider consisting of two resistors, which is arranged in parallel with the second capacitor. The voltage detection device is electrically conductive via a switching device with the Semiconductor switch connected. Another capacitor is arranged parallel to this connection and discharges through the switching device at the moment of ignition. The switching device can be a one-sided trigger diode or a two-sided trigger diode. The semiconductor switch can e.g. B. be designed as a thyristor, the control input of which is connected to the switching device.

It proves to be disadvantageous here that the series connection of the choke and the secondary winding of the transformer represents a large reactive load for the AC voltage source. In order to keep the reactive load for the AC voltage source as low as possible, it is necessary to choose a low transmission ratio for the transformer. However, this means that ignition voltages greater than 10 kV are not or difficult to reach with this device. In order to be able to achieve ignition voltages greater than 10 kV, it is necessary to supply the ignition circuit with a high primary voltage. However, it proves to be disadvantageous that the components of the ignition circuit and in particular the semiconductor switch must be designed as high-voltage-resistant components and no standard components can be used, as a result of which the device can often not be produced cost-effectively. Furthermore, it turns out to be disadvantageous in the known device that although the semiconductor switch is controlled as a function of a predetermined voltage value of the second capacitor, a phase-correct ignition of the gas discharge lamp is not guaranteed or is only guaranteed by chance, as a result of which rapid and safe ignition of the gas discharge lamp often does not take place.

The invention has for its object to provide a device which is simple and inexpensive, which ensures reliable ignition of a gas discharge lamp and which enables safe, inexpensive operation of a gas discharge lamp, the reactive load for to minimize the AC voltage source through the transformer.

The object is achieved in that the secondary winding of the transformer, the first capacitor and the gas discharge lamp form a first series resonant circuit and that the resonance frequency of the first series resonant circuit corresponds to the fundamental frequency of the voltage of the AC voltage source.

It is advantageous that the secondary winding of the transformer, the first capacitor and the gas discharge lamp form a first series resonant circuit and that the resonance frequency of the first series resonant circuit corresponds to the fundamental frequency of the voltage of the AC voltage source, because the reactive load for the AC voltage source is as low as possible when the gas discharge lamp is operated is held and thus the AC voltage source does not have to be designed for large reactive loads, which can save costs. In addition, it proves to be advantageous that the transmission ratio of the transformer can be selected to be very large without the secondary winding of the transformer representing a noticeable reactive load for the AC voltage source and without the ignition circuit having to be supplied with high voltage, which requires that the components of the ignition circuit and in particular the semiconductor switch, are designed to withstand high voltages, as a result of which inexpensive standard components can be used and high-voltage protective measures for the ignition circuit are not required, which contributes to simple and inexpensive manufacturability of the device. In this context, it is advantageous that ignition voltages greater than 10 kV can be generated in a simple and inexpensive manner and that a gas discharge lamp can be operated safely.

Further advantageous refinements and developments of the subject matter of the invention result from the subclaims.

Because the AC voltage source is a DC / AC converter, there is the advantage that a gas discharge lamp operated with AC voltage can be connected to a DC voltage source, in particular to a DC voltage source in a motor vehicle.

It is advantageous that a trigger output of the DC / AC converter is connected to the switching device because a trigger signal or a frequency signal which is in phase with the AC voltage is supplied to the switching device in a simple and inexpensive manner, as a result of which the semiconductor switch is in phase with the Frequency of the AC voltage can be controlled.

The fact that the switching device has a logic digital component results in the advantage that the semiconductor switch is only controlled in a defined manner when a signal is present at the same time from the voltage detection device and the DC / AC converter.

Characterized in that the switching device has a timing element, there is the advantage that the semiconductor switch is actuated by the switching device only at the point in time that enables the gas discharge lamp to be lit in the correct phase, thereby ensuring quick and safe ignition of the gas discharge lamp.

It is advantageous that a voltage multiplier is arranged between the AC voltage source and the ignition circuit, because in a simple and inexpensive manner a sufficiently high voltage is provided for the ignition circuit from a low AC voltage, which ensures that an ignition voltage that is sufficient is achieved to ignite a gas discharge lamp that requires an ignition voltage that is greater than 10 kV.

Characterized in that a series connection of a third capacitor and a first resistor is arranged between the connections of the AC voltage source, there is the advantage that the AC voltage source is protected in a simple and inexpensive manner against effects of the high ignition voltage, thereby ensuring the safety of the operation of the Device is increased and possible harmful overshoots of the switching edges of the DC / AC converter are damped.

It is particularly advantageous that the DC / AC converter supplies a square-wave voltage or a pulse-width-modulated voltage, which makes it possible to control the power in the operation of the gas discharge lamp in a simple and inexpensive manner, and in particular in the start-up phase after the gas discharge lamp has been ignited a higher power can be supplied than is required for the continuous operation of the gas discharge lamp.

Characterized in that a second series resonant circuit is arranged in the connection between the first output terminal of the DC / AC converter and the first series resonant circuit, which is formed by a first inductance and a fourth capacitor, that a parallel resonant circuit between the second series resonant circuit and the first series resonant circuit branches second output terminal, which is formed by a second inductor and a fifth capacitor, there is the advantage that the gas discharge lamp is supplied with a sine-like voltage required for its operation even if the DC / AC converter at the first output terminal no square wave voltage, but supplies rectangular pulses with a variable time interval that is too large to maintain the gas discharge without interposing the filter arrangement described.

In this context, it is particularly advantageous that the resonance frequency of the second series resonant circuit and Parallel resonant circuit corresponds in each case to the fundamental frequency of the voltage of the AC voltage source, because large reactive loads for the AC voltage source are thus avoided in a simple and inexpensive manner, as a result of which an AC voltage source can be used in a cost-effective manner.

It is advantageous that the capacitances of the first capacitor, the fifth capacitor and the fourth capacitor are of the same size and that the inductances of the first inductor and the second inductor correspond to the inductance of the secondary winding of the transformer, because in this way it is avoided that large harmonic components are avoided The voltage from the pulse-width-modulatable DC / AC converter with a different design of the inductances and capacitances of the second series resonant circuit and / or the parallel resonant circuit creates an excessive reactive load for the pulse-width modulator, especially since the secondary winding is selected in this way that it has the greatest possible inductance in order to achieve a high transmission ratio of the transformer.

Characterized in that a first terminal is arranged in the connection between the first output terminal and the voltage multiplier or the secondary winding, that a second terminal is arranged in the connection between the second output terminal and the voltage multiplier or the gas discharge lamp and that in the connection between the Trigger output and the switching device is arranged a third terminal, there is the advantage that the device can be disconnected at these terminals and that at least two gas discharge lamps with the associated ignition circuits can be connected to an AC voltage source, which can reduce costs.

It is advantageous that the first output terminal is electrically conductively connected to a phase comparator, that a fourth terminal, which is connected to the connection between the first series resonant circuit and the gas discharge lamp, is electrically conductively connected to the phase comparator, that the phase comparator is connected to a voltage-controlled one Oscillator is connected and that the oscillator is electrically conductively connected to a third input terminal of the DC / AC converter, which is a synchronization input, because in this way a phase comparison between the voltage from the AC voltage source and the voltage is carried out in a simple and inexpensive manner of the gas discharge lamp, the phase comparison is a measure of whether the inductances and capacitances of the first and / or second series resonant circuit and / or the parallel resonant circuit have tolerances that lead to large reactive loads for the AC voltage source, from the phase ver the same a voltage signal is generated which drives the voltage controlled oscillator in such a way that it generates a frequency signal which synchronizes the DC / AC converter via the third input terminal so that the phase difference is regulated to zero.

The fact that a first voltage detection circuit is arranged in the connection between the first output terminal and the phase comparator results in the advantage that a voltage signal suitable for further processing is fed to the phase comparator. The same advantage results from the fact that a second voltage detection circuit is arranged in the connection between the fourth terminal and the phase comparator.

The fact that the phase comparator and the oscillator are combined in an integrated component results in the advantage of a simple and inexpensive construction of the device.

It is advantageous that a power meter is electrically conductively connected to the fourth terminal via a third voltage detection circuit, that the power meter is connected via a fifth terminal to a current detection circuit which is in the connection between the second output terminal and the gas discharge lamp, in close proximity to the Gas discharge lamp is arranged, because in a simple and cost-effective way a power determination and power detection during the operation of a gas discharge lamp is made possible, which is the basis for a power control of the gas discharge lamp.

In this context, it is particularly advantageous that the power meter is connected to a fourth input terminal of the pulse-width-modulated DC / AC converter, because a signal is supplied to the DC / AC converter, the size of which is a measure of that of the Gas discharge lamp is power consumed and that the DC / AC converter can be used to control the power to be made available to the gas discharge lamp.

The fact that the power meter is a multiplying pulse width pulse height modulator and that the power meter is connected to a frequency output of the DC / AC converter, which is connected to a sawtooth oscillator, has the advantage that the power meter is supplied with a frequency signal that corresponds to the frequency corresponds to the voltage of the AC voltage source and which can be used as a reference voltage for the multiplication.

Because the third voltage detection circuit generates a voltage signal which corresponds to the mean value of the voltage at the fourth terminal, a voltage signal is supplied to the power meter for the power determination, which enables an exact determination of the power, since the gas discharge lamp is supplied with a low-harmonic, sine-like voltage , the current through the

Gas discharge lamp is also sinusoidal and the current and voltage at the gas discharge lamp are only slightly out of phase in their fundamental waves. The same advantage results from the fact that the current detection circuit generates a voltage signal that corresponds to the mean value of the current at the gas discharge lamp. The active power consumption of the gas discharge lamp can thus be determined by the product of the rectified mean values of current and voltage.

The fact that the device can be disconnected via the terminals results in the advantage that at least two gas discharge lamps can be connected to an AC voltage source, which can contribute to an inexpensive construction of the device.

Exemplary embodiments of the subject matter of the invention are shown in the drawings and are described in more detail below with reference to the drawings.

• Figur 1 ein erstes Ausführungsbeispiel einer Schaltungsanordnung der erfindungsgemäßen Einrichtung,
• Figur 2 ein zweites erweitertes Ausführungsbeispiel einer Schaltungsanordnung der erfindungsgemäßen Einrichtung zum Zünden und Betreiben elektrischer Gasentladungslampen.
• Figur 3 ein drittes erweitertes Ausführungsbeispiel einer Schaltungsanordnung der erfindungsgemäßen Einrichtung.

Show it

• FIG. 1 shows a first exemplary embodiment of a circuit arrangement of the device according to the invention,
• Figure 2 shows a second extended embodiment of a circuit arrangement of the device according to the invention for igniting and operating electrical gas discharge lamps.
• Figure 3 shows a third extended embodiment of a circuit arrangement of the device according to the invention.

The same or equivalent parts are provided with the same reference numerals in all figures.

Figure 1 shows a DC / AC converter (W), which has two input terminals (E1, E2). The input terminals (E1, E2) can be electrically conductive with a Be connected to a DC voltage source, which in particular can be the battery of a motor vehicle.

The DC / AC converter (W) has two output terminals (AC, 0V). The first output terminal (AC), to which an AC voltage is applied, is connected to a gas discharge lamp (G) via a secondary winding (LS) of a transformer (U) and a first capacitor (C1). The gas discharge lamp (G) is also connected to the second output terminal (0V) of the DC / AC converter (W). The secondary winding (LS), the first capacitor (C1) and the gas discharge lamp (G) form a first series resonant circuit, the resonance frequency of which corresponds to the fundamental frequency of the AC voltage which is present at the first output terminal (AC) of the DC / AC converter (W). In order to protect the DC / AC converter (W) from effects caused by high ignition voltages, a third capacitor (C3.) Is to be found in the connection between the first output terminal (AC) and the second output terminal (0V) of the DC / AC converter (W) ) arranged. In order to dampen possible harmful overshoots of the switching edges of the DC / AC converter (W), a first resistor (R1) is arranged in series with the third capacitor (C3).

In order to be able to ignite the gas discharge lamp safely, the device according to the invention has an ignition circuit. So that the ignition circuit can generate an ignition voltage via the transformer (U), which ensures that the gas discharge lamp (G) ignites, a voltage multiplier (SV) is provided, which is electrically conductive with the first output terminal (AC) of the DC / AC converter ( W) is connected and has an output that outputs an increased voltage to the ignition circuit. In addition, the voltage multiplier (SV) has an output which is electrically conductively connected to the second output terminal (0V) of the DC / AC converter (W).

The ignition circuit consists of a second capacitor (C2), the first electrode of which is electrically conductive with the second Output terminal (0V) of the DC / AC converter (W) is connected and the second electrode is electrically conductively connected to the output of the voltage multiplier (SV), to which an increased voltage is applied, and on the other hand to the primary winding (LP) of the Transmitter (U) is connected, which is also part of the ignition circuit. The ignition circuit also has a semiconductor switch (H), which is connected on the one hand to the primary winding (LP) of the transformer (U) and on the other hand to the second output terminal (0V) of the DC / AC converter (W).

In order to be able to charge the second capacitor (C2) to a high charge potential, the voltage multiplier (SV) supplies the second capacitor (C2) with a DC voltage.

In order to generate a control signal that says that the second capacitor (C2) has a voltage sufficient to ignite the gas discharge lamp (G), a voltage detection device (SP) is arranged in parallel with the second capacitor (C2) in the ignition circuit. In order to control the semiconductor switch (H) at the point in time at which the voltage detection device (SP) has generated a control signal, the voltage detection device (SP) is connected to the semiconductor switch (H) in an electrically conductive manner via a switching device (S).

In order to ensure that the semiconductor switch (H) is driven in the correct phase, the switching device (S) is also electrically conductively connected to a trigger output (T) of the DC / AC converter (W). So that the semiconductor switch (H) is only closed and thus causes the gas discharge lamp (G) to ignite when the second capacitor (C2) has a predetermined voltage and at the same time a trigger signal at the trigger output (T) of the DC / AC converter (W) is present, the switching device (S) has a logic component that only sends a signal to the Semiconductor switch (H) switches through when the two signals mentioned are present simultaneously.

In order to ensure that the gas discharge lamp (G) is fired in phase, the switching device (S) can have a timing element that determines the point in time at which the semiconductor switch (H) is switched to a point in time which ensures that the ignition voltage is in the phase of the gas discharge lamp (G) the transformer (U) is supplied.

The semiconductor switch (H) can advantageously be designed as a thyristor, as a TRIAC or, with a slight modification of the circuit, as a transistor.

The gas discharge lamp (G) can in particular be a high-pressure alternating current gas discharge lamp which requires an ignition voltage greater than 10 kV for reliable ignition. In order to generate an ignition voltage of this order of magnitude, the transmission factor of the transformer (U) is approximately 50. The transmission factor can be chosen larger or smaller depending on the specified requirements. The components used in the ignition circuit, in particular the semiconductor switches (H), can thereby be designed as non-high-voltage-resistant standard components in order to save costs. Since the resonance frequency of the first series resonant circuit corresponds to the frequency of the AC voltage from the DC / AC converter (W) during operation of the gas discharge lamp (G), the secondary winding (LS) of the transformer (U) has a minimum reactive load for the DC / AC Transducer (W), which means that it does not have to be designed for high reactive loads, thus ensuring cost-effective manufacture of the device according to the invention.

The function of the device according to the invention is briefly described below using an application example.

When starting up the device according to the invention, which has the purpose of igniting and operating the gas discharge lamp (G), a DC voltage is applied to the two input terminals (E1, E2) of the DC / AC converter (W), which has a predetermined value having. Since the gas discharge lamp (G) requires a high-frequency AC voltage for ignition and operation, the DC / AC converter (W) converts the DC voltage into a high-frequency AC voltage, which in this example has a frequency of approximately 10 kHz. The frequency can be selected higher or lower depending on the requirements.

In order to achieve the ignition of the gas discharge lamp (G), the second capacitor (C2), which serves as an ignition capacitor, is charged to a predetermined voltage via a voltage multiplier (SV), which contains a rectification circuit. In another exemplary embodiment, a voltage multiplier (SV) is not required, depending on the design of the transformer (U) and / or the ignition voltage required to ignite the gas discharge lamp (G). If a predetermined voltage is present at the second capacitor (C2) and is recognized by the voltage detection device (SP), the voltage detection device (SP) outputs a control signal to the switching device (S). In order to achieve a phase-correct switching of the semiconductor switch (H), the semiconductor switch (H) is only activated by the switching device (S) if, in addition to the control signal from the voltage detection device (SP), a predetermined trigger signal from the trigger output (T) of the DC / AC converter (W) is present. In order for the gas discharge lamp (G) to be ignited in phase, the switching device (S) can have a timing element that determines the time of switching of the semiconductor switch (H) in such a way that any switching delays that may be present due to the semiconductor switch (H) or the transformer ( U) are balanced so that the ignition voltage from the ignition circuit is supplied in phase to the gas discharge lamp (G) becomes. If the semiconductor switch (H) is switched to the closed state, the voltage stored in the second capacitor (C2) discharges through the primary winding (LP) of the transformer (U) and generates a predetermined ignition voltage in the lamp circuit, the required ignition energy being used Protection of people can be kept as small as possible.

After the gas discharge lamp (G) has been successfully ignited, it is operated by the AC voltage which is present at the first output terminal (AC) of the DC / AC converter (W). Because the resonance frequency of the first series resonant circuit corresponds to the fundamental frequency of the AC voltage, the reactive load for the DC / AC converter (W) is kept as low as possible, which can lead to energy savings.

FIG. 2 shows an expanded circuit arrangement of the device according to the invention, which makes it possible to carry out a power control of the gas discharge lamp. In order to be able to control the power of the gas discharge lamp, the DC / AC converter can supply a square-wave voltage or a pulse-width-modulated voltage.
An AC voltage is present at the first output terminal (AC). B. can be a square wave voltage. In order to reduce the power to be passed to the gas discharge lamp (G), the pulse-width-modulatable DC / AC converter (W) can generate a periodic alternating voltage which has a variable pulse-pause ratio.

So that the gas discharge lamp (G) does not go out after a successful ignition by an insufficient voltage during the pause times from the pulse-pause modulator, the circuit arrangement has an extension to the circuit arrangement shown in FIG. 1, which ensures that the Gas discharge lamp (G) is continuously supplied with a sinusoidal voltage, which ensures safe, continuous operation of the Guaranteed gas discharge lamp (G). The filter arrangement here consists, for example, of a second series resonant circuit, which is arranged between the first output terminal (AC) and the first series resonant circuit, consisting of the secondary winding (LS), the first capacitance (C1) and the gas discharge lamp (G), and a parallel resonant circuit, which is arranged between the second series resonant circuit and the first series resonant circuit. The second series resonant circuit consists of a first inductance (L1) and a fourth capacitor (C4) and is arranged between the first output terminal (AC) of the AC voltage source and a first terminal (K1), which is on the one hand electrically conductive with the first series resonant circuit and on the other is electrically connected to the voltage multiplier (SV). The parallel resonant circuit consists of a fifth capacitor (C5) and a second inductance (L2), each branching off between the second series resonant circuit and the first terminal (K1) to the second output terminal (0V).

In order to keep the reactive loads for the AC voltage source (AC, 0V) low, the resonance frequencies of the second series resonant circuit and the parallel resonant circuit, like the resonance frequency of the first series resonant circuit, correspond to the fundamental frequency of the voltage of the AC voltage source (AV, 0V). Since large harmonic components occur during operation with a pulse-width-modulated voltage signal, it is also necessary that the capacitances of the first capacitor (C1), the fifth capacitor (C5) and the fourth capacitor (C4) are the same and that Inductances of the first inductance (L1) and the second inductance (L2) correspond to the inductance of the secondary winding (LS) of the transformer (U) in order to avoid large reactive loads for the AC voltage source (AC, 0V) caused by the second series resonant circuit and the parallel resonant circuit can be generated due to the harmonic components of the voltage. This dimensioning of inductors and capacitors is particularly because of this important, since the inductance of the secondary winding (LS) of the transformer (U) must be chosen as large as possible in order to obtain a large transmission ratio of the transformer (U), which means that with a small ignition voltage in the ignition circuit, a high ignition voltage for the gas discharge lamp (G) can be provided.

A second terminal (K2) is arranged in the connection between the second output terminal (0V) and the gas discharge lamp (G) in such a way that it lies between the parallel resonant circuit and the gas discharge lamp (G) or the voltage multiplier (SV). A third terminal (K3) is arranged in the connection between the trigger output (T) of the DC / AC converter (W) and the switching device (S). This arrangement of the terminals (K1, K2, K3) makes it possible in a simple and inexpensive manner to separate the circuit arrangement of the device according to the invention at this point, the area in which a high voltage may be present being different from the area for reasons of safety Power supply can be separated and which also makes it possible to connect at least two gas discharge lamps (G) with their ignition circuits to an AC voltage source (AC, 0V), in particular using time division multiplexing, which can result in considerable cost savings.

FIG. 3 shows a circuit arrangement of the device according to the invention for igniting and operating a gas discharge lamp that has been expanded to the exemplary embodiment shown in FIG.

The resonant circuits of the device according to the invention described in the exemplary embodiment in FIG. 2 have capacitances and inductances which inevitably have tolerances when the device is constructed inexpensively and which can fluctuate greatly, particularly when operated in a motor vehicle, since large temperature differences can occur, in particular if if the components are arranged near the gas discharge lamp (G) or a reflector which contains the gas discharge lamp (G), which can result in a shift in the resonance frequencies of the resonant circuits to the fundamental frequency from the AC voltage source (AC, 0V). In order to avoid that such a shift of the resonance frequencies of the resonant circuits to the fundamental frequency of the voltage from the AC voltage source (AC, 0V) results in high reactive loads for the AC voltage source (AC, 0V), regulation of the fundamental frequency is to minimize the reactive loads by the resonant circuits the voltage of the AC voltage source (AC, 0V) is provided, by which the fundamental frequency of the voltage of the AC voltage source (AC, 0V) is adapted to the resonance frequency of the resonant circuits.

In order to achieve such a regulation of the fundamental frequency of the voltage of the AC voltage source (AC, 0V), a phase comparator (P) is electrically conductively connected to the first output terminal (AC) via a first voltage detection circuit (V1) and electrically conductively via a second voltage detection circuit (V2) electrically connected to a fourth terminal (K4) which is connected to the connection between the first series resonant circuit and the gas discharge lamp (G). The first and the second voltage detection circuit (V1, V2) serve to supply the phase comparator (P) with suitably prepared voltages for further processing. In another exemplary embodiment, the first and the second voltage detection circuit (V1, V2) can be dispensed with if the phase comparator (P) can process the voltage signals from the first output terminal (AC) and the fourth terminal (K4) directly.

The phase comparator (P) forms a direction-dependent voltage signal from the two phase-dependent voltage signals from the first output terminal (AC) and the fourth terminal (K4) Phase comparator (P) connected, voltage-controlled oscillator (A) is supplied. The voltage-controlled oscillator (A) is electrically conductively connected to a third input terminal (E3) of the DC / AC converter (W) and supplies a direction-dependent frequency signal. The third input terminal (E3) of the DC / AC converter (W) is a synchronization input. The direction-dependent frequency signal from the voltage-controlled oscillator (A) changes the frequency of the AC voltage via the synchronization input of the DC / AC converter (W) until a phase difference in the voltages from the first output terminal (AC) and the fourth terminal (K4) is no longer present and thus the frequency of the AC voltage source (AC, 0V) corresponds to the resonance frequency of the resonant circuits of the device according to the invention.

In order to achieve a simple and inexpensive construction of the device according to the invention, the phase comparator (P) and the voltage-controlled oscillator (A) can be combined in one integrated component.

To detect the power at the gas discharge lamp (G), the circuit arrangement has a power meter (M) which is connected in an electrically conductive manner to a fourth input terminal (E4) of the pulse-width-modulatable DC / AC converter (W). The power meter (M) is also electrically conductively connected to the fourth terminal (K4) via a third voltage detection circuit (V3), as a result of which the power meter (M) is supplied with a voltage which corresponds to the mean value of the voltage at the fourth terminal (K4). In order to supply the power meter (M) with a voltage which corresponds to the mean value of the current at the gas discharge lamp (G), the power meter (M) is connected in an electrically conductive manner via a fifth terminal (K5) to a current detection circuit (I) which is in the connection is arranged between the second output terminal (0V) and the gas discharge lamp (G) in the immediate vicinity of the gas discharge lamp (G). Another one The third voltage detection circuit (V3) can be omitted if the second voltage detection circuit (V2) can supply the power meter (M) with a corresponding voltage signal from the fourth terminal (K4). To ensure simple and inexpensive power recording and determination, the power meter (M) is electrically conductively connected to a frequency output (FA) of the DC / AC converter (W), which supplies the power meter (M) with an AC voltage signal, in particular a sawtooth voltage , which serves as a reference voltage for the multiplication in a known manner by means of a pulse width pulse height modulator and whose frequency can correspond to the basic frequency of the AC voltage source (AC, 0V). One thus obtains in a simple and inexpensive manner the possibility of power detection on the gas discharge lamp (G), which is the basis for the power control and which ensures that the gas discharge lamp (G) can be operated safely and in different operating states.

The terminals (K1, K2, K3, K4, K5) also ensure here, as in the exemplary embodiment in FIG. 2, that the device according to the invention can be separated at these terminals (K1, K2, K3, K4, K5), whereby it is achieved that at least two gas discharge lamps (G) with their ignition circuits can be connected to an AC voltage source (AC, 0V), in particular in time-division multiplexing, and that the part of the circuit arrangement in which a high voltage can be generated is separated from the rest of the part the circuit arrangement is made possible, whereby the safety during possible maintenance work and during the operation of the gas discharge lamp (G) is increased.

Claims (21)

1. Device for igniting and operating electrical gas discharge lamps, in particular in motor vehicles, with an AC voltage source to which a gas discharge lamp is connected, with a transformer whose secondary winding is arranged in series with the gas discharge lamp and which forms a resonant circuit with a first capacitor and whose primary winding Is part of an ignition circuit, which contains a second capacitor and a semiconductor switch, with a voltage detection device in the ignition circuit, which is connected to the semiconductor switch via a switching device, characterized in that the secondary winding (LS) of the transformer (U), the first capacitor ( C1) and the gas discharge lamp (G) form a first series resonant circuit and that the resonance frequency of the first series resonant circuit corresponds to the fundamental frequency of the voltage of the AC voltage source (AC, 0V). 2. Device according to claim 1, characterized in that the AC voltage source (AC, 0V) is a DC / AC converter (W). 3. Device according to claim 2, characterized in that a trigger output (T) of the DC / AC converter (W) is connected to the switching device (S). 4. Device according to claim 3, characterized in that the switching device (S) has a logical digital component. 5. Device according to claim 4, characterized in that the switching device (S) has a timing element. 6. Device according to claim 1, characterized in that between the AC voltage source (AC, 0V) and Ignition circuit a voltage multiplier (SV) is arranged. 7. Device according to claim 6, characterized in that the voltage multiplier (SV) generates a DC voltage. 8. Device according to claim 1, characterized in that a series circuit comprising a third capacitor (C3) and a first resistor (R1) is arranged between the connections of the AC voltage source (AC, 0V). 9. Device according to at least one of the preceding claims, characterized in that the DC / AC converter (W) supplies a square wave voltage or a pulse-width-modulated voltage. 10. The device according to claim 9, characterized in that in the connection between the first output terminal (AC) of the DC / AC converter (W) and the first series resonant circuit, a second series resonant circuit is arranged by a first inductance (L1) and one fourth capacitor (C4) is formed that between the second series resonant circuit and the first series resonant circuit branches a parallel resonant circuit to the second output terminal (0V), which is formed by a second inductance (L2) and a fifth capacitor (C5) and that the resonance frequency of the second Series resonant circuit and the parallel resonant circuit each correspond to the fundamental frequency of the voltage of the AC voltage source (AC, 0V). 11. The device according to claim 10, characterized in that the capacitances of the first capacitor (C1), the fifth capacitor (C5) and the fourth capacitor (C4) are the same size and that the inductances of the first inductor (L1) and the second inductor (L2) correspond to the inductance of the secondary winding (LS) of the transformer (U). 12. The device according to claim 11, characterized in that a first terminal (K1) is arranged in the connection between the first output terminal (AC) and the voltage multiplier (SV) or the secondary winding (LS) that in the connection between the second Output terminal (0V) and the voltage multiplier (SV) or the gas discharge lamp (G) a second terminal (K2) is arranged and that in the connection between the trigger output (T) and the switching device (S) a third terminal (K3) is arranged . 13. The device according to claim 12, characterized in that the first output terminal (AC) is electrically conductively connected to a phase comparator (P), that a fourth terminal (K4) connected to the connection between the first series resonant circuit and the gas discharge lamp (G) is connected in an electrically conductive manner to the phase comparator (P), that the phase comparator (P) is connected to a voltage-controlled oscillator (A) and that the oscillator (A) is electrically conductive to a third input terminal (E3) of the DC / AC Converter (W) is connected, which is a synchronization input. 14. Device according to claim 13, characterized in that a first voltage detection circuit (V1) is arranged in the connection between the first output terminal (AC) and the phase comparator (P). 15. Device according to claim 13, characterized in that a second voltage detection circuit (V2) is arranged in the connection between the fourth terminal (K4) and the phase comparator (P). 16. The device according to claim 13, characterized in that the phase comparator (P) and the oscillator (A) are combined in an integrated component. 17. The device according to claim 13, characterized in that a power meter (M) is electrically conductively connected via a third voltage detection circuit (V3) to the fourth terminal (K4), that the power meter (M) via a fifth terminal (K5) with a Current detection circuit (I) is connected, which is arranged in the connection between the second output terminal (0V) and the gas discharge lamp (G), in close proximity to the gas discharge lamp (G), that the multiplier (M) with a fourth input terminal (E4) of the pulse-width-modulatable DC / AC converter (W) is connected. 18. The device according to claim 17, characterized in that the power meter (M) is a multiplying pulse width pulse height modulator and that the power meter (M) with a frequency output (FA) of the DC / AC converter (W) is connected to one Sawtooth oscillator is connected. 19. The device according to claim 18, characterized in that the third voltage detection circuit (V3) generates a voltage signal which corresponds to the mean value of the voltage at the fourth terminal (K4). 20. The device according to claim 18, characterized in that the current detection circuit (I) generates a voltage signal which corresponds to the mean value of the current at the gas discharge lamp (G). 21. The device according to claim 17, characterized in that the device via the terminals (K1, K2, K3, K4, K5) can be separated.

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