WO2011144403A1 - Circuit arrangement for igniting high-pressure discharge lamps - Google Patents

Abstract

The invention proposes a circuit arrangement for igniting a high-pressure discharge lamp, in which a high-voltage capacitor (C2) charged up to the ignition voltage of the lamp (XBO) is switched to the electrodes of the lamp (XBO) via a switching spark gap (FS2). This has the advantage that virtually all of the energy stored in the high-voltage capacitor (C2) is available to ignite the high-pressure discharge lamp (XBO). As a result, reliable ignition and arc transfer are achieved at reduced stray electromagnetic radiation.

Description

 description

Circuit arrangement for igniting high-pressure discharge lamps

Technical area

The invention relates to a circuit arrangement for igniting high-pressure discharge lamps, in particular noble gas discharge lamps such as are used for example for the cinema ^¬ projection.

Depending on the high-pressure discharge lamp type, different ^starting voltages are required, with noble gas discharge lamps up to typically 40 kV or more. These relatively high ignition voltages - for cold and in particular for hot noble gas discharge lamps - are caused by the inert gas filling, for example, only xenon or noble gas mixtures.

State of the art

In previous generic Zündschaltungsanordnungen (see Fig. 1), a capacitor Cl is charged by means of a high voltage generator HV1 and then switched via a switching spark gap FS1 to a tap or primary ^¬ winding WP of a Tesla transformer TR. The capacitor C 1 then discharges in the serial LC resonant circuit formed by the primary winding WP. Between the ends of the secondary winding WS of the transformer TR, a higher secondary voltage, which is translated by the turns ratio of both transformer windings and the coupling factor, is produced, which ignites the connected xenon high-pressure discharge lamp XBO. After the ignition phase, the actual operating device BG takes over the operation the high-pressure discharge lamp XBO. The Lam ^¬ penbetriebsstrom flows through the secondary winding WS of the transformer TR. Incidentally, the lamp operating voltage is considerably lower than the lamp starting voltage and is typically about 25-45V. Depending on the power consumption of the lamp, for example, a few hundred to a few thousand watts, flow considerable currents, typically in the range of about 20-200A.

Document EP 0 975 007 B1 discloses in FIG. 2 a circuit arrangement based on this ignition circuit principle.

A disadvantage of the prior art is that the Zündgerä ^¬ te are relatively expensive and in particular require a Trans ^¬ formator. Especially with lamps with high noble gas cold filling pressure ignition is uncertain with devices of the prior art and usually requires several ignition pulses. This general ignition problem is exacerbated by the decreasing ignitability of the lamps with increasing operating time.

DESCRIPTION OF THE INVENTION The object of the present invention is to propose a circuit arrangement which enables an improved ignition of high-pressure discharge lamps.

This object is achieved by a circuit arrangement for igniting a high-pressure discharge lamp, in particular noble gas discharge lamp, having two output terminals for at ^¬ close the high-pressure discharge lamp, and a high voltage capacitor which is connected to a high voltage generator, the one connection of the high voltage capacitor via a switching spark gap with a first output pole and the other terminal of the high-voltage capacitor is connected directly to the second output ^¬ pole. Particularly advantageous embodiments can be found in the dependent claims.

The circuit arrangement according to the invention has the advantage that almost the entire energy stored in the high-voltage capacitor, namely only less the energy loss due to the switching spark gap, is available for the ignition of the high-pressure discharge lamp. Since ^¬ by the ignition pulse delivers significantly more energy than the initially explained Tesla Coil concept according to the prior art. The higher Energieeinkopp- development leads to significantly better acquisition of unloading ^¬ charge arc through to the ignition phase provided for the Be ^¬ drove additional operating unit. In addition, the ignition pulse is wider than in the prior art, which on the one hand causes a more reliable ignition - usually only one ignition pulse is required - and also causes less electromagnetic interference, since less high-frequency components are involved in the ignition pulse.

The output of the electrical operating device must also be connected to their power supply to operate a high-pressure discharge lamp. Therefore, a first output terminal of the operating device is connected via a throttle to an output terminal for connecting the high-pressure discharge lamp. This protects the throttle from ^¬ transition of the operating device during the ignition phase of the high-voltage pulse. The choke must be in its current carrying ability of the lamp to be adapted. From the second ^¬ gangspol of the operating device is connected to the second gangspol from ^¬ for connecting the high-pressure discharge lamp. The throttle preferably consists of a piece of current ^¬ conductor and at least one ferrite component, through which the current conductor is passed. The Stromlei ^¬ ter is at least in the region of the ferrite, unwound, preferably straight. Depending on the required inductance of the current choke - typically from 25 to more than 50 μΗ - several ferrite components can be arranged linearly along the conductor. Particularly suitable as ferrite components are also easily assembled hinged ferrite. The scarf spark gap is preferably designed so that their breakdown voltage corresponds approximately to the maximum charging voltage of the high voltage capacitor. This design is usually carried out on the distance between the electrodes of the spark gaps and the type and pressure of the filling gas used. Since the terminal of the switching ^¬ spark gap opposite to the end connected to the high voltage capacitor terminal is above the throttle near the reference potential of the high voltage capacitor, falls over the unfired scarf t spark gap almost all the charging voltage of the high voltage capacitor from. This ignites the switching spark gap as soon as the high voltage generator has fully charged the high voltage capacitor. The high voltage capacitor ^¬ may be made in the rest of two or more In parallel or in series connected capacitors of appropriate capacity and withstand voltage. Brief description of the drawings

In the following, the invention will be explained in more detail with reference to an embodiment ^¬ example. The figures show:

1 shows a circuit arrangement according to the prior art,

Fig. 2 shows an embodiment of the invention

 Circuitry,

3 shows an embodiment of the current choke for the circuit arrangement according to the invention,

4 shows an ignition pulse of the circuit arrangement according to the invention from FIG. 2 (200ns / div), FIG.

5 shows an ignition pulse of the circuit arrangement from FIG. 1, according to the prior art (80ns / div), FIG.

Fig. 6 shows the time courses for lamp current i and lamplight

 I according to the circuit arrangement according to the invention from FIG. 2 (20ys / div),

7 shows the time profiles for lamp current i and lamp light

 I according to the circuit arrangement of Fig. 1, according to the prior art (40ys / Div).

Preferred embodiment of the invention

2 shows a schematic representation of an embodiment of the circuit arrangement according to the invention for igniting a high-pressure discharge lamp XBO whose power supply lines 1, 2 are connected to the two output poles AI, A2 of the circuit arrangement. This embodiment is designed for a DC-powered 4000 W Xenon noble gas lamp type XBO® from OSRAM GmbH. The direct current (DC) operation takes place after the ignition of the lamp XBO with the aid of a DC operating device BG. Des ^¬ sen first Ausgangspol al is connected via a throttle L with the first output terminal AI for connecting the anode of the high-pressure discharge lamp XBO. From the second ^¬ gangspol a2 of the DC operating device BG is directly connected to the second output terminal A2 for connecting the cathode of the high-pressure discharge lamp XBO. In addition, the two output poles al, a2 of the DC operating device BG to the input of a high voltage generator HV2 verbun ^¬ the. The output of the high voltage generator HV2 is connected to a high voltage capacitor C2 and charges it in the ignition phase to about 40 kV. The second output pole a2 of the DC operating device BG forms here the common reference potential for the high voltage generator HV2 and the high voltage capacitor C2. The high voltage terminal of the high voltage capacitor C2 is connected via a switching spark gap FS2 to the first output terminal AI. During the charge phase, the high voltage capacitor C2, the other terminal of the Schaltfun ^¬ kenstrecke FS2 via the current inductor L is static so that almost the entire charging voltage of the high voltage capacitor C2 drops to close to reference potential, via the Schaltfun- kenstrecke FS2. The switching spark gap FS2 is designed for a breakdown voltage of up to 40 kV. Thereby, the switching spark gap FS2 turns on, so ^¬ soon the high voltage capacitor C2 is charged to 40 kV, and applies the charging voltage of the Hochspannungskondensa- tors C2 to the first output terminal AI and thus to the anode of the high-pressure discharge lamp XBO. This na ^¬ hezu the energy of the high-voltage capacitor C2 - namely only minus the losses in the switching spark gap FS2 - provided for the ignition of the high-pressure discharge lamp XBO. During ignition, the current choke L blocks the output pole of the operating device BG against the high voltage.

The high-voltage generator HV2 is designed in a manner known per se to the person skilled in the art. Here, the A ^¬ output voltage, which can vary between 80 and 150 V here, stepped up to approximately 5 kV high voltage. This is followed by an eight-stage high-voltage multiplier, which ultimately provides an output voltage of approximately 40 kV.

In Fig. 3, the throttle L is shown in s chemical form. It consists of an approximately 20 cm long, straight and insulated copper wire 3, on which, for example, five rectangular ferrite components 4, each about 25 mm long, are lined up. Due to the linear structure results in a high dielectric strength. A casting this on ^¬ superstructure to provide the high voltage strength sure is not required. Further advantages are that the current-carrying wire does not have to be laboriously wound and no special copper wire is required (eg 4x8mm ² wound upside down with sufficient gap because of dielectric strength), no special ferrite shape is needed and easy to use for different lamp powers by adjusting the wire diameter is. For a lamp power of 4000 W, the wire cross-sectional area is approximately 32 mm ² .

FIG. 4 shows the curve of the ignition voltage pulse U measured on the circuit according to FIG. 2. A time unit (DIV) between the long bars of the time axis t is 200ns. Compared to the embodiment shown in FIG. 5 corresponding representation for the circuit of the prior art, the ignition voltage U with the inventive circuit of FIG. 2 is substantially wider and therefore causes less electromagnetic ^¬ any electromagnetic interference. When comparing Figures 4 u. 5, it should be noted that the time axis t of FIG. 5 is already stretched by a factor of 2.5 (80 ns / DIV). As compared recognizable, the first half-cycle of the ignition pulse with the inventive circuit is about two and a half times longer and has correspondingly less subharmonic Frequenzan parts ^¬.

In FIG. 6, the overall with the circuit of FIG. 2 measured time courses of the lamp current i and the Lam ^¬ penlichtes I are shown. Compared to the corresponding representation of the circuit according to the prior art shown in FIG. 7, the circuit according to the invention quickly establishes a stable operating current. This also takes the lamplight immediacy ^¬ bar after ignition not degrade as it does in Fig. 7, that is the danger that the lamp after the ignition starts again before the operating device takes over the lamp current is significantly reduced. This improved ignition and takeover behavior is essentially attributed to the fact that with the circuit according to the invention during ignition more energy is fed into the lamp.

Claims

 claims Circuit arrangement for igniting a high-pressure discharge lamp, in particular noble gas discharge lamp (XBO), with two output terminals (AI, A2) for connecting the high-pressure discharge lamp (XBO), and a high-voltage capacitor (C2), which is connected to a high voltage generator (HV2) wherein said one terminal of the high voltage capacitor (C2) via a switching spark gap (FS2) having a first off ^¬ gangspol (AI) and the other terminal of the high tensioning ^¬ voltage capacitor (C2) is directly connected to the second off ^¬ gangspol (A2). 2. Circuit arrangement according to claim 1 with an additional operating device (BG) for operating the high-pressure discharge lamp (XBO) after its ignition, wherein a first Ausgangspol (al) of the operating device (BG) via a throttle (L) with a Ausgangspol (AI) for connecting the high-pressure discharge lamp (XBO) is ver ^¬ connected and wherein a second output pole (a2) of the operating device (BG) to the second output terminal (A2) for connecting the high-pressure discharge lamp (XBO) is connected. 3. Circuit arrangement according to claim 1 or 2, wherein the inductor (L) consists of a conductor (3) and at least one ferrite component (5), through which the current conductor (3) is guided. Circuit arrangement according to claim 3, wherein the current conductor (3) at least in the region of the ferrite component (5) unwound, preferably straight. Circuit arrangement according to claim 3 or 4, wherein a plurality of ferrite components (5) along the conductor (3) are lined up linearly. 6. Circuit arrangement according to one of claims 3 to 5, wherein the or the ferrite components (5) are formed as Klappferrite te. 7. Circuit arrangement according to one of claims 2 to 6, wherein the inductor is designed for an inductance of 25 to 50 μΗ. Circuit arrangement according to one of the preceding claims, wherein the high-voltage generator (HV2) and the high-voltage capacitor (C2) are designed so that the high-voltage capacitor (C2) is charged to at least the ignition voltage of the high-pressure discharge lamp to be ignited (XBO). S cha 1 t s o o nnection according to claim 8, wherein the switching spark gap (FS2) is designed so that its breakdown voltage corresponds approximately to the charging voltage of the high voltage capacitor (C2).