FI113736B - Coupling device for operation of a discharge lamp - Google Patents

Abstract

The gas-discharge tube (LP) with e.g. its preheater (VH) is connected to the output of a generator (G) of AC at a predetermined high frequency from the mains supply. A control input of the generator is connected to a switch-off device (AV) producing a signal (CS1) when activated by the detector (VE) of the peak-to-peak voltage across the lamp. The output (UA) of the detector is proportional to the detected peak-to-peak voltage. When this output exceeds a threshold value the generator is switched off.

Description

113736

Connection arrangement for operating the discharge lamp

The invention relates to a switching arrangement for using a discharge lamp according to the preamble of claim 1.

Such patented switching arrangements without the use of a cut-off device for the use of fluorescent lamps are proposed in DE patent applications Nos. 3,623,749.3 and 3,611,611.4. It is disadvantageous in these circuits that in the event of a malfunctioning of the lamp, the lamp is not switched off. Therefore, based on the mode of operation of the active harmonic filter through which energy is continuously pumped back to the filter capacitor, the filter capacitor may be destroyed in the event of a lamp failure.

On the other hand, a cutting device such as that disclosed in the preamble of the first claim is known from DE-A-2 941 822. This cut-off device comprises a trigger circuit having a precisely defined diacid that unlocks the thyristor with a deceleration of about one second. However, the deceleration time of up to one second is for a switching arrangement having a pump system. a harmonic filter formed by a method, too long, because in much shorter times, a strong rise in voltage in the filtering capacitor can occur.

* '·' A switching system is known from EP 0 276 460 »1« | M. 'arrangement for high-frequency use of a vacuum discharge lamp V' · having a cut-off device capable of switching the cut-off device within a thyristor of milliseconds. In the case of a 30-stroke offset of a vacuum discharge lamp, an increase in voltage is induced in the filter through the capacitors of the active harmonic filter. If the / voltage rise exceeds the break-through voltage of one or more zener diode (s) connected to the trigger circuit, these ·; · 35 diodes switch through and thus directly trigger the cut-off »2 113736 device thyristor. This switching arrangement makes it possible to cut off when the vacuum discharge lamp is off; however, it is unable to detect the so-called "End-of-live" state (e.g., single-sided emitter discharge on electro-5 rod) and similar switching operations. In addition, this switching arrangement is not capable of detecting a symmetrical or asymmetrical rise in lamp voltage in a timely manner and with sufficient accuracy.

Starting from this prior art, the invention is based on 10 tasks to create a switching arrangement of the aforementioned kind, which allows switching off in various fault situations of the discharge lamp.

This object is solved by a switching arrangement having the features of claim 1.

15 The discharge lamp is continuously tested for malfunction conditions, using peak-to-peak voltage (Peak-Peak voltage) as a criterion. These error states include e.g. a so-called rectifier effect (different lamp voltage amplitudes with respect to both voltage waves 20; asymmetric lamp voltage rise) and symmetrical lamp voltage rise, for example, through "micro leakage" (drawing air into the lamp body).

According to the invention, the Peak-Peak voltage is used as a pa-V parameter for detecting various error states.

According to a preferred embodiment of the present invention, a control signal is generated from the voltage detection device of the lamp to represent a voltage proportional to the peak-to-peak voltage. Thus, in addition to the Peak-Peak voltage itself, physical parameters derived from this ··· 30 voltage can also be used.

Other preferred embodiments of the present invention are defined in the dependent claims.

The invention will now be described with reference to the drawings. In the drawings: 1

f I I I

3 113736 Fig. 1 is a block diagram of a switching arrangement according to the invention and Fig. 2 is an example of a switching technique for forming a voltage detection device in a switching arrangement according to Fig. 1.

The switching arrangement illustrated in Figure 1 operates for low or high frequency operation of the discharge lamp LP. In this case, low frequency refers to the magnitude of the frequency corresponding to the network frequency, while high frequency Merit) narrows the frequency above such low frequency.

On the input side, the switching arrangement according to the invention has a generator G which produces, for example, high-frequency voltage. Generally, generator G 15 produces an alternating voltage to operate the discharge lamp. On the inlet side, generator G is connected to the mains voltage, e.g., by a voltage supply part not shown in the figure, e.g. a mains rectifier.

The discharge lamp LP may be connected, for example, to 20 preheating devices VH.

The generator G for generating an AC frequency voltage has a control input connected to r 1

,. to the generator cut-off device AV. This cut-off device AV

'produces the first 25 control signals CS1, depending on the input signal CS21. The first control signal CS1 activates * ··· 'the generator G in such a way that the generation of the AC frequency is stopped.

V 1 According to the invention there is provided a voltage detecting device VE, which, on the other hand, is connected to the electrodes of the discharge lamp · 1: · 30 and which in the example shown in Fig. 1 takes the voltage Use of the discharge lamp LP. Voltage detector. Depending on the detected lamp voltage, the device VE generates a (second) control signal CS2. This control signal 1 'li CS2 is applied to a generator cut-off device AV. This 35 (second) control signal, which is applied to the generator circuit. 113736 4 activates this cut-off device AV in such a way that the cut-off device generates a first control signal CS1 and thus prevents the generation of AC voltage.

The voltage detection device VE may also generate a second control signal CS2 which is formed from a voltage UA proportional to the Peak-Peak voltage. This cut-off device AV may be designed in such a way that it generates a first control signal CS1, as long as the UA proportional to the Peak-Peak voltage exceeds a predetermined threshold.

The voltage detection device shown in Figure 2 is formed, for example, by a voltage multiplication circuit known per se. According to the invention, this multiplication circuit of the δ-15 is used to detect different error states of the discharge lamp.

In this switching arrangement, a voltage divider Rx, R2 having a Peak-Peak voltage Uss is provided on the inlet side on the side facing the lamp LP.

20 Apply a voltage proportional to the lamp voltage between the ground and the center of the voltage divider • Um. The middle tap of the voltage divider is fitted first. capacitor C1 having a center-to-tap side of the voltage divider connected to the anode of both the first 25 diodes D1 and the cathode of the second diode D2. The anode D2 of the second diode D1 is connected to ground. The cathode of the first diode D1 is connected. · At the output of the drive DE, a second capacitor ·· 30 C2 is connected between the ground and the cathode of the first diode D1.

In the negative half wave of the voltage Um, a second diode D1 of the maximum negative voltage of the lamp LP is charged; '· Nitrogen. In the positive semiconductor of voltage Um, the first capacitor C1 is discharged through the first; 35 diodes D1 to the second capacitor C2. Thereby the sum of the 113736 volatile voltages Um and the voltage Uc1 formed in the negative half wave of the voltage Um are applied. The voltage thus formed corresponds to the Peak-Peak voltage Uss. The voltage UM in the center tap of the voltage divider represents the proportional portion of the voltage U8e.

Diode D1 and capacitor C2 operate to store the detected Peak-Peak voltage U8S.

The peak-to-peak voltage Use or Um is generated when the oscillator AV 10 connected to the capacitor C2 in parallel has infinite impedance (VE not loaded through AV; idle case).

Conversely, if the cut-off device AV fitted in parallel with capacitor C2 has a finite impedance, then the given waveform of the lamp voltage transmits a value proportional to the Peak-Peak voltage li8S or UB.

The signal generated in the manner described above (for both unloaded and loaded conditions) may be combined with the additional dimensions, especially the operating voltage, since in the connection according to the invention a signal proportional to the Peak-Peak voltage is produced with respect to the reference grounding of the generator circuit.

The first diode D1 may be replaced by a zener diode. Independently of this, the second diode D2 can also be replaced by a generic diode.

According to the invention, the voltage detection switches -> / ·· can be compared with the voltage generated by the cell VE. The Ra value for cut-off for overvoltage (symmetrical and asymmetric ··· 30 meters) can be adjusted regardless of the cut-off response time in the ignition (voltage divisors Rx, R2 and, ·. Capacitor C2).

; The use of zener diodes for D1 and D2 instead of • normal diodes enables the use of a smaller capacitor C2 with the same response time in the ignition process.

6 113736

In the switching arrangement according to the invention, the Peak-Peak voltage can be directly applied (R 1 = 0).

More generally, the coupling arrangement of Fig. 2 according to the invention is constructed with relatively few standard coupling parts which together form a very cost-effective solution. At the same time, this coupling structure with few components ensures that this coupling has a high reliability.

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Claims (4)

7 113736 A method for breaking a switching arrangement for operating a discharge lamp (LP) using a predetermined frequency 5, comprising: (i) generating (G) an alternating voltage for operating a discharge lamp (LP) at a predetermined frequency, (ii) a cut-off device (AV) 10 and generating, depending on the second control signal (CS2), a first control signal (CS1) by means of which the generator can be controlled and activated such that in the event of a symmetrical increase in voltage across the discharge lamp, the alternating voltage is stopped; a TE (VE) coupled to a cut-off device (AV) which detects a peak-to-peak voltage value (Uss) acting across the discharge lamp (LP) and generates a second control signal (CS2) proportional to the peak-to-peak voltage value (Uss), known as si that the second control signal (CS2) is compared to a threshold value in the cut-off device (AV), the first control signal:: (CS1) being produced to break the switching arrangement when the threshold value is exceeded, based on both a symmetric and λ Method according to Claim 1, characterized in that the voltage detection device (VE) comprises a voltage divider (R1, R2) coupled to a discharge !!! 30 lamps (LP). Method according to Claim 2, characterized in that the voltage divider (R1, R2) is at a defined reference potential and is connected to its medium soak to the breaking device (AV) via a first capacitor (Cl) and a first diode (D1). , and that the second diode (D2) is arranged between the defined reference potential and the junction point of the first capacitor (C1) and the first diode (D1), and that the second capacitor (C2) is arranged parallel to the defined reference potential and the first diode (D1). with the input of the cut-off device 5 (AV). Method according to Claim 3, characterized in that the first and / or second diode (D1, D2) is in each case a zener diode. «· * 9 113736