DE1923872A1 - Ignition device for electric discharge tubes - Google Patents

Description

DR. ING. F. WTIESTHOFF 1923872 ⁸ MUNICH 9O

DIPIi. ING. G. PTJXS SCEW £ IOEBSIRASSS S

DR.E.V.PECHMANN tklkfok ssoeoi DR. ING. D. BEHRENS tmbobammadbbssb. PATENT LAWYERS PBOTBOTPATBKT münohjen

1A-36310

Description of the patent application

OY NOKIA AB, Helsinki, Finland

concerning
Ignition device for electric discharge tubes

The present invention relates to an ignition device for electrical discharge tubes, in which the necessary ignition voltage is generated with the help of a transformer.

In the known ignition devices or ignition circuits with a transformer, a leakage field transformer is usually used worked, its open circuit voltage to ignite the discharge tube sufficient and its tension equal under load the operating voltage of the tube was. Design the efficiency, purchase price and dimensions of the stray field transformer However, so unfavorable that one endeavored for the Throttling of the tube current a series choke and besides to provide a separate ignition circuit. The ignition circuits customary today are generally condenser thermal relay holders or pulse generator circuits with a certain frequency, e.g. 1 kHz. The former circuit works slowly, i.e. it can happen that in the case of discharge tubes that are difficult to ignite, the electrodes cool down again before the next Voltage surge reached. The reliable ignition of the lamp is therefore not guaranteed under all circumstances. The latter circuits have the disadvantage that the ignition pulses often are only directed unilaterally, this fact works sioh namely negative on the electrodes and the combustion chamber

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the lamp off, because the impulses charged with high energy -.._ ;. then only transport the matter in one direction * The,, The consequence of this is that the electrodes wear out more quickly and possibly also a blackening of the glass surface, what emerges from again there is a premature sharp decrease in the light intensity even before the normal service life of the lamp has expired.

The present invention is based on the object of providing an ignition device, in particular the last does not have or result in the disadvantages mentioned.

The solution to this problem in an ignition device for electrical discharge tubes, in which the ignition voltage is generated with a transformer, is that according to the invention, the primary current of the transformer during each IBLbphase through one in two directions Triode thyristor, which is controlled by a bi-directional diode thyristor, which in turn feeds its electricity via an intermediate tap of the discharge tube, the combination of resistor and capacitor connected in parallel receives and that the power values of resistor and capacitor are chosen so that when the discharge tube burns the voltage at the intermediate tapping parts of the Resistor-capacitor combination lower than the ignition voltage of the diode thyristor which is permeable in two directions, or that the brimary current of the transformer is set to corresponding Is routed via another suitable switching element, that switches when the target voltage is reached.

Ignition device according to the invention offers a number of important advantages. So can the transformer with regard to its dimensions can be kept small, since it only serves to generate the ignition pulse and thus not the loads by the discharge tube current. On the

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Borrowed and failure-prone thermal relays can be completely dispensed with The ignition device delivers within a half-phase several successive bidirectional Ignition pulses that guarantee reliable ignition.

Immediately after the lamp has been ignited, the ignition device w ± d switched off.

The ignition device according to the invention is particularly suitable for filling the difficult-to-ignite multi-metal discharge lamps with gas to ionize and heat their electrodes by electrical discharges so that the ignition process is made possible. However, the ignition device or ignition circuit constructed according to the invention is also ideally suited for igniting other items Discharge base of working fluorescent tubes as well as for bringing about electrical discharges at a desired frequency.

The invention and advantageous details of the invention are based on an advantageous embodiment example Figures explained in detail. The figures show:

1 shows the circuit diagram of an embodiment of an ignition device according to the invention, in which this is connected upstream of a discharge tube, the current of which through a choke is limited,

Fig. 2 is a circuit diagram of another embodiment of a Ignition device according to the invention, in which the transformer with the choke which limits the tube current, directly is coupled.

In FIG. 1, the reactor 2 and the discharge tube 10 are connected in series. Parallel to the discharge tube 10 is the ■ Combination resistor 8 - capacitor 9 switched, their on Tapped switched two-way diode thyristor '"DIAC" 7 the ignition pulse si η the two-way tribdenthyristor "TRIAC" 6 there. A £

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of the "TRIAC" 6 is coupled to one network pole while the other pole is connected to the primary coil of the transformer 5, which in turn is connected in series with the capacitor 3. The secondary side of the transformer 5 lies on the discharge tube 10 in series with capacitor 4.

The ignition device works as follows: If the circuit is closed with switch 1, the voltages rise at the poles of the combination of resistor 8 and capacitor 9. After the constant time determined by 8 and 9 has elapsed shows the voltage across the capacitor to the breakdown voltage value of the "DIAC" 7. "DIAC" 7 breaks down, "TRIAC" 6 becomes conductive and lets a strong current surge through the primary coil of the transformer, which causes the capacitor to charge. This creates high voltage peaks in the secondary coil, which are conducted to the discharge tube 10 via the capacitor 2. The same thing happens with the other half-wave. With regard to the ignition function, the components 8 and 9 are selected so that "TRIAC" 6 at the line voltage range 310 "V ignites. Since this peak adds up to the voltage supplied by the igniter, the igniter can be used for lower power and Voltage output can be designed. When the discharge tube ignites, its pilot voltage and the voltage of the capacitor decrease 9 no longer reaches values so high that "DIAC" 7 would break through, so that the ignition device works automatically comes to a standstill. Thanks to the operating principle of the ignition device, this may be in the discharge tube or short-circuit occurring in the switching elements. The capacitor 4 is, as far as the operation of the circuit is concerned, dispensable; he has lent IeJjJl the job of the transformer to protect against the mains voltage and to make it possible to get by with a small transformer,

The detonator in this form is ideal for installation in place of an old detonator, as the pre-

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direction can be built with small dimensions and a total of only three lines have to be routed »the secondary coil can be switched past the choke, since the impedance in the network is only low and the latter, as far as the ignition pulse is concerned, as can be considered short-seeded. The ignition voltage is present then directly on the lamp. The secondary winding of the transformer 5 and the capacitor 4 can also be dispensed with entirely will. It then only needs, as shown in Figure 2, an auxiliary winding 12 to be placed in the choke 11, which with "TRIAO" 6 is switched in the same way as the primary winding of transformer 5 in Mg. 1. This is recommended Arrangement of course not, because firstly the choke of the old detonator would have to be replaced and secondly with long lines because of their impedance, part of the power would be lost and cause disturbances in the environment.

The figures and their explanations are only intended to serve the purpose of illustrating the idea of the invention. It goes without saying that these are within the scope of the claim the most diverse.Variationen with regard to the embodiment and type of connection of the invention are possible.

Claim

909 850/0763

Claims (1)

Claim Ignition device for electric discharge tubes, "at which the ignition voltage is generated with a transformer, characterized in that the primary current of the transformer is passed through a triode thyristor (6) permeable in two directions during each half phase, which is controlled by a bi-directional diode thyristor (7), which in turn feeds its current Via intermediate tapping of a combination of resistor (8) and capacitor connected in parallel with the discharge tube (9) receives, and that the power values of resistor (8) and capacitor (9) are chosen so that when the discharge tube is burning the voltage at the intermediate tap of the resistor-capacitor combination is lower than the ignition voltage of the in two-way diode thyristor is permeable, or that the primary current of the transformer is in a corresponding way is guided via another suitable switching element that switches when the target voltage is reached. 909850/0763