JPH033359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multiple series discharge lamp lighting device, which absorbs variations in the lifespan of each discharge lamp and improves discharge lamp replacement efficiency. Provide configuration.

Figure 1 shows a two-lamp series sequential starting type lighting circuit as an example of a multi-lamp series discharge lamp lighting device. Discharge lamps 6 each independently forming discharge lamp groups 4 and 5 are connected to the output end of the leakage transformer 2 via a phase advancing capacitor 3.
7 are connected in series, and a sequence capacitor 8 for starting assistance is connected in parallel with the discharge lamp 6. The input winding 2a of the leakage transformer 2 is the preheating winding 9, 10, 11 which is a preheating circuit that preheats each filament of the discharge lamps 6, 7 with the same preheating voltage.
are transformer coupled.

When the commercial power supply 1 is turned on in such a circuit, the output voltage of the leakage transformer 2 changes to the phase advance capacitor 3.
and is applied to the discharge lamp 7 via the sequence capacitor 8, and the discharge lamp 7 slightly discharges and reaches a starting state.
When the discharge lamp 7 is slightly discharged, the impedance of the sequence capacitor 8 is very large compared to the impedance of the discharge lamp 7, so most of the above output voltage is applied to the sequence capacitor 8, and this voltage causes the voltage to flow in parallel with the sequence capacitor 8. The related discharge lamp 6 starts, and the discharge lamps 6 and 7 proceed to stable lighting using the inductance of the leakage transformer 2 and the phase advance capacitor 3 as current limiting elements.

The lighting device shown in FIG. 1 uses the well-known starting assist function of the sequence capacitor 8 as described above to smoothly start the discharge lamps 6 and 7 connected in series, leading to lighting. When the inventor conducted a so-called short-term flashing lamp life test on such a device by turning on and off the commercial power supply 1 at intervals of 10 seconds, and repeating this, the inventor discovered that the discharge lamp 6 was superior to the other discharge lamp. It has been found that the filament breaks or the electron emitting substance called emitter disappears more quickly than electric lamp 7.

This is because at the beginning of the start-up of the discharge lamp 7, that is, at the time of slight discharge, the flow of slight discharge flowing into the discharge lamp 7 is small due to the intervention of the high-impedance sequence capacitor 8, and when the other discharge lamp 6 is started, the discharge lamp 7 reaches its rated lighting. The discharge current gradually increases until the transition occurs, and the energetic stress applied to the discharge lamp 7 gradually increases.However, the voltage across the sequence capacitor 8 increases rapidly when the discharge lamp 7 starts, and the discharge current increases gradually. This voltage, which is close to the output voltage of the leakage transformer 2, is applied to the lamp 6 all at once, and a large discharge current tries to flow all at once to reach the rated lighting. This is thought to be due to added stress.

The present invention has been made in view of these drawbacks.

That is, to describe the present invention using the circuit shown in FIG. 1 as an example, the number of turns of preheating windings 9 and 10 is
The number of turns is larger than 1, and the filament preheating current of the discharge lamp 6 is made larger than the preheating current of the other discharge lamp 7.

As is well known, increasing the preheating current promotes the emission of electrons from the filament, relieves stress on the filament when voltage is applied, allows the discharge lamp 6 to start smoothly, and extends the life of the discharge lamp 3. Therefore, the difference in lifespan between the discharge lamps 6 and 7 can be almost eliminated.

Therefore, even if both lamps are replaced at the same time when one of the discharge lamps reaches the end of its life, the lamp cost will not increase, and lamp replacement efficiency can be greatly improved.

In addition, in the above embodiment, since the number of turns of the preheating winding 10 and the preheating winding 11 is different, the preheating current of the discharge lamp 7 is different between the two filaments, but in practical terms, there is a problem that the life of the discharge lamp 7 is shortened. Of course, the preheating winding 10 may be divided into two windings and four preheating windings may be provided, each preheating a different filament.

Figure 2 shows an example for four lamps, where two discharge lamp groups 4 and 5 connected in series each have two discharge lamps 1.
2, 13, 14, and 15, and the sequence capacitor 8 is connected in parallel with the discharge lamp group 4 by connecting one end of the output of the leakage transformer 2 and the connection point of the discharge lamp groups 4 and 5. Preheating winding 1 for preheating the filaments of the discharge lamps 12 and 13
The above-mentioned example for two lamps in that the number of turns of windings 6, 17, and 18 is set larger than the number of turns of preheating windings 19, 20, and 21 that preheat the filaments of discharge lamps 14 and 15 of the other discharge lamp group 5. The configuration is different.

The operation is the same as that shown in FIG.
After that, discharge lamp group 4, which had been previously supplied with a larger preheating current than discharge lamps 14 and 15, started.
The discharge lamps 12, 13 start very smoothly, and all the discharge lamps 12...15 shift to rated lighting.

In each of the above examples, the preheating circuit is connected to the leakage transformer 2 by the preheating windings 9...11,
16...21, the preheating current can be easily adjusted by simply changing the number of turns, but a preheating power supply may be provided separately to form a preheating circuit.

As described above, the present invention creates a difference in the filament preheating current of the discharge lamp between a group of discharge lamps connected in parallel with the sequence capacitor and a group of discharge lamps connected in series, thereby increasing the preheating current of the former discharge lamp. As a result, the difference in lamp life between the two groups of discharge lamps was reduced, and even if all lamps were replaced at the same time, the lamp cost did not increase significantly, making it possible to increase lamp replacement efficiency.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a two-lamp series discharge lamp lighting device which is the basis of the present invention, and FIG. 2 is a circuit diagram showing an example in which the present invention is applied to four lamps. 1...Commercial power supply, 2...Leakage transformer,
4, 5... Discharge lamp group, 6, 7, 12, 13, 1
4, 15... Discharge lamp, 8... Sequence capacitor, 9, 10, 11, 16, 17, 18, 19,
20, 21... Preheating winding.

Claims (1)

[Claims] 1 Two discharge lamp groups, each formed by series connection of one or more discharge lamps each having a filament, are connected in series to both ends of an AC power source via a current limiting element, and started in parallel with one discharge lamp group. In a multi-lamp series discharge lamp lighting device, which is connected to an auxiliary sequence capacitor and is provided with a preheating circuit that supplies preheating current to the filaments of the discharge lamps in each discharge lamp group, the preheating circuit is connected in parallel with the sequence capacitor. A multi-light series discharge lamp lighting device characterized in that a filament preheating current of one discharge lamp group is made larger than a filament preheating current of the other discharge lamp group.