JPH0327357Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] This invention relates to a discharge lamp lighting device that lights discharge lamps such as fluorescent lamps at high frequency using an inverter device, and is particularly suitable for lighting multiple discharge lamps at once. This invention relates to a simple and effective means of protecting an inverter device in a half-wave discharge state at the end of a discharge lamp's life.

[Background technology]

FIG. 2 shows a circuit diagram of this conventional discharge lamp lighting device. In Fig. 2, 1 is a commercial power supply, 2 is a power switch, 3 is a rectifier bridge, 4 is a smoothing capacitor, 5 is an inverter device, 25 is a discharge lamp, 2
6 is an inductor, and the inverter device 5 includes an inductor 27, resistors 28, 29,
A push-pull transistor inverter consisting of transistors 30 and 31, a capacitor 32, and a leaky oscillation transformer 33 is shown.

When the power switch 2 is turned on, the commercial power source 1 is rectified and smoothed by the rectifier bridge 3 and the smoothing capacitor 4 to form a DC power source E. Transistors 30 and 3 are connected to this DC power supply E through resistors 28 and 29.
1 of the drive current flows, the transistors 30 and 31 are turned on and off alternately by the action of the feedback winding of the oscillation transformer 33, and a high-frequency sine wave with a resonant frequency determined by circuit constants such as the inductance of the capacitor 32 and the oscillation transformer 33 is generated. It is well known that a wave output is generated, and the discharge lamp 25 is lit by this inverter output.

The discharge lamp 25 has a fixed rated life, and if it is lit for a certain period of time, the emitter applied to the electrode filament will disappear, leading to a defect, but in the process, the emitter of one of the electrode filaments will disappear. There is a half-wave discharge condition due to the first discharge. In other words, since there is no more electron emission from the electrode with no emitter,
It exhibits characteristics as if a diode were connected in series with the discharge lamp 25.

In such a state, the inverter device 5
The output also becomes a half-wave, and the load on either the transistors 30 or 31 increases, causing abnormal heat generation or thermal runaway, leading to destruction. The inductor 26 in FIG. 2 is provided to eliminate the inconvenience in such a half-wave discharge state.
Usually designed with a fairly large inductance value,
Care is taken to ensure that there are no problems with starting or lighting characteristics.

By adding the inductor 26, even when the discharge lamp 25 enters a half-wave discharge state, a bypass current will flow through the inductor 26, and the half-wave output of the inverter device 5 will be eliminated to some extent. Transistors 30, 31 by half-wave discharge
It also reduces the burden on From this point of view, the smaller the inductance value of the inductor 26, the better, which contradicts the consideration given to the starting characteristics and lighting characteristics described above. Therefore, a saturable reactor is used as the inductor 26, and it is designed to have a high inductance value during normal times, and to use the saturation of the iron core to have a low inductance only when high voltage is applied during half-wave lighting. It has been devised.

FIG. 3 shows a circuit diagram of another conventional discharge lamp lighting device (three-lamp series lighting type). In Fig. 3, 10, 11, 12 are discharge lamps, 21,
22 is a sequence capacitor for sequential lighting, 26
is an inductor (saturable reactor).

In this discharge lamp lighting device, when a starting voltage is applied to the discharge lamps 10 to 12, the discharge lamp 12 first discharges via the sequence capacitors 21 and 22,
Since the tube voltage is reduced, most of the inverter output voltage is applied to the discharge lamps 10 and 11, leading to lighting.
In this way, in series lighting, successive lighting using sequence impedance is effective for starting, but a considerably higher starting voltage is required than in the case of a single discharge lamp. Even in series lighting, the half-wave discharge state at the end of the discharge lamp life similarly occurs, so the inductor 26 is connected to the output terminal of the inverter device 5 as in the case of Fig. 2, but the inverter output is designed to be high. Therefore, there is a risk of abnormal heat generation when there is no load, which creates a contradiction in that the inductor 26 needs to be made larger, and at the same time, as the inductor 26 becomes larger, the effect of stress reduction due to half-wave discharge also decreases.

FIG. 4 shows a circuit diagram of yet another conventional discharge lamp lighting device (six lamps in series and parallel lighting type using a balancer). In Figure 4, 6 is a balancer, 7-1
2 is a discharge lamp, 19 to 22 are sequence capacitors, 23 and 24 are inductors (saturable reactors)
It is.

In this discharge lamp lighting device, when a starting voltage is applied, voltage is applied to the series circuit of discharge lamps 7, 8, 9 and the series circuit of discharge lamps 10, 11, 12 through the balancer 6, and the sequence capacitor 19 ，
20 and the discharge lamp 12 are discharged first through the sequence capacitors 21 and 22, respectively, and then the discharge lamps 7, 8 and 10, 1 are discharged.
1 lights up sequentially.

In this case, as in the case of FIG.
one of the two terminals, e.g. discharge lamps 7, 8,
9 is removed, the discharge lamps 10, 11, and 12 on the other side of the balancer 6 remain lit, so the balancer 6 acts as an autotransformer and the inductor 23 connected to the side from which the discharge lamp is removed is A very large voltage is generated. Therefore, the dielectric breakdown voltage of the inductors 23 and 24 is also required.
It becomes expensive.

Note that it is naturally possible to connect the inductors 23 and 24 at the output end of the inverter device 5 in the same way as shown in Fig. 3, but the connection shown in Fig. 4 has a greater protective effect during half-wave discharge. It seems so. In addition, in series-parallel lighting as shown in Figure 4, if there are no inductors 23 and 24, even if only one discharge lamp connected in series causes a half-wave discharge, the discharge lamps in parallel are lit. , the stress on the inverter device 5 is also small, but if, for example, the discharge lamps 9 and 12 in FIG. The stress will also increase.

[Purpose of invention]

The purpose of this invention is to provide a discharge lamp lighting device that can reduce stress on an inverter device due to half-wave discharge that occurs at the end of the life of a discharge lamp when multiple discharge lamps are lit at once.

[Disclosure of invention]

The discharge lamp lighting device of this invention includes a DC power source, an inverter device supplied with power from the DC power source, a balancer having a common terminal connected to one output end of the inverter device, and a first individual terminal of the balancer. a first series circuit of a plurality of discharge lamps connected between the other output terminal of the inverter device; and a first series circuit of a plurality of discharge lamps connected between the second individual terminal of the balancer and the other output terminal of the inverter device. 2, and the first and second plurality of discharge lamps excluding the discharge lamp closest to the other output terminal of the inverter device in the series circuit of the first plurality of discharge lamps. A plurality of first inductors each connected in parallel to all the discharge lamps in a series circuit of electric lamps, and a discharge lamp closest to the other output terminal of the inverter device in the series circuit of the first plurality of discharge lamps. A connection point between the discharge lamp and another discharge lamp adjacent to this discharge lamp, a discharge lamp closest to the other output terminal of the inverter device in the series circuit of the second plurality of discharge lamps, and a connection point adjacent to this discharge lamp. and a second inductor connected between the discharge lamp and the connection point with another discharge lamp.

Then, the inductance value of the inductor connected in parallel to the discharge lamp closest to the other output terminal of the inverter device in the series circuit of the second plurality of discharge lamps is set to The inductance value of the second inductor is set to be sufficiently larger than the inductance value of all the remaining inductors among the plurality of first inductors.

According to the configuration of this invention, when the series circuit of the first and second plurality of discharge lamps is connected to the output end of the inverter device via the balancer to light up the plurality of discharge lamps at once, A first inductor is connected in parallel to all discharge lamps except for one discharge lamp constituting a series circuit of discharge lamps.
A connection point between a discharge lamp closest to the other output terminal of the inverter device in a series circuit of a plurality of discharge lamps and another discharge lamp adjacent to this discharge lamp, and a second series circuit of a plurality of discharge lamps. Because I connected a second inductor between the discharge lamp closest to the other output terminal of my inverter device and the connection point of other discharge lamps adjacent to this discharge lamp, one of the discharge lamps was half-wave discharged. However, current flows in both directions through the inductor, reducing stress on the inverter device.Moreover, each inductor shares the voltage, so high voltage is not applied to each inductor, and each inductor can be small, reducing stress. It can fully demonstrate its functions, requires no measures against dielectric breakdown, and is inexpensive.

Also, since the inductance value of one of the multiple inductors connected in parallel to each discharge lamp is set to be sufficiently larger than the inductance value of the remaining inductors, the inductor with a relatively small inductance value is selected during startup. Since it can act as an impedance and the boosting effect of the balancer can be utilized, starting performance is extremely good even when series-parallel lighting is performed.

Furthermore, a connection point between the discharge lamp closest to the other output terminal of the inverter device in the series circuit of the first plurality of discharge lamps and another discharge lamp adjacent to this discharge lamp, and the second plurality of discharge lamps are connected to each other. A second inductor is connected between the discharge lamp closest to the other output terminal of the inverter device in the series circuit of and the connection point of another discharge lamp adjacent to this discharge lamp, and this second inductor Since the inductance value of is set to be approximately the same as the inductance value of all the remaining inductors among the plurality of first inductors, the other output terminal of the inverter device in the series circuit of the second plurality of discharge lamps. Even if the discharge lamp closest to the discharge lamp is removed, stress can be reduced by reducing the voltage applied to the inductor with a large inductance value connected in parallel to this discharge lamp.

Furthermore, even if any of the discharge lamps malfunctions, the remaining discharge lamps continue to be lit, so it is possible to immediately identify which discharge lamp has reached the end of its life.

〔Example〕

FIG. 1 shows a circuit diagram of a discharge lamp lighting device according to an embodiment of this invention. This 6-lamp series-parallel type discharge lamp lighting device connects the common terminal of the balancer 6 to one output terminal of the inverter device 5, and the balancer 6
A series circuit of discharge lamps 7, 8, 9 is connected between the first individual terminal of the balancer 6 and the other output terminal of the inverter device 5, and a series circuit of discharge lamps 7, 8, 9 is connected between the first individual terminal of the balancer 6 and the other output terminal of the inverter device Discharge lamp 10,1 between
1, 12 series circuits are connected, discharge lamps 7, 8, 1
Inductors 13 to 17 (first) at 0, 11, and 12
are connected in parallel. Inductors 13-16 act as sequence impedances in place of sequence capacitors 19-22 in FIG. Inductor 17 is set to about 10 times the inductance value of inductors 13 to 16.

In addition, the connection point of the discharge lamps 8 and 9 and the discharge lamps 11 and 1
An inductor (second) 18 is connected between the two connection points. This inductor 18 is set to have an inductance value comparable to that of the inductors 13 to 16. The other configurations are the same as the conventional example.

In this discharge lamp lighting device, when a power switch 2 is turned on, a commercial power source 1 is rectified and smoothed by a rectifier bridge 3 and a smoothing capacitor 4 (series power source E), and an inverter device 5 is driven. Inverter device 5
A specific example of the configuration is as shown in FIG. 2, and the inverter output is taken out from the output winding of the leaky oscillation transformer 33. It should be noted that the inverter device 5 is not limited to this example, as long as it generates a high frequency output and also includes elements as a ballast for the discharge lamps 7 to 12.

Among the discharge lamps 7, 8, 9 connected in series, inductors 13, 1 are connected in parallel to the discharge lamps 7, 8.
4 acts as a sequence impedance. Further, inductors 15, 16, 1 are connected in parallel to the discharge lamps 10, 11, 12 connected in series.
7, inductors 15 and 16 act as sequence impedance, and the remaining one inductor 17 needs to have a sufficiently larger inductance value than the above-mentioned two inductors 15 and 16 (to improve starting performance). , from the experimental results about 10
If it is about twice as much or more, it will have almost no effect on startability.

Next, the starting process will be explained. Inverter output voltage is discharge lamps 7 to 12 and inductor 1
The voltage is applied to a circuit consisting of components 3 to 17 via a balancer 6. For example, first, the inverter output voltage is applied to the discharge lamp 9 via the inductors 13 and 14,
The discharge lamp 9 starts discharging. The voltage of the discharge lamp 9 drops to the tube voltage during discharge, and most of the inverter output voltage is applied to the discharge lamps 7 and 8.
8 and 9 are sequentially lit. Discharge lamp 7, 8, 9
When the lamp is turned on, the voltage boosted by the boost function of the balancer 6 is applied to the discharge lamp 12 via the inductors 15 and 16, and discharge starts. The voltage of the discharge lamp 12 drops to the tube voltage during discharge,
Most of the inverter output is applied to the discharge lamps 10, 11, and the discharge lamps 10, 11, 12 are sequentially lit.

After each of the discharge lamps 7 to 13 is turned on, both series circuit currents are balanced by the action of the balancer 6.

Further, among the discharge lamps 7 to 12, for example, discharge lamp 1
0 is the life span, and when half-wave discharge is performed, an inductor 1 is connected in parallel with each discharge lamp 10 to 12.
5, 16, and 17 are connected, the direct current component can be bypassed, and therefore, the conversion of the inverter output to direct current due to half-wave discharge can be alleviated. in this case,
If the inductance value of the inductor 17 is very large, the DC moderation effect of the inverter output will be reduced during half-wave discharge of the discharge lamp 12. Therefore, set the inductance value to an appropriate value, and then
If the inductance value of No. 16 is set to about 1/10 or less, the design is easy and good startability can be maintained.

Furthermore, as mentioned in the explanation of the conventional example,
In the case of series-parallel lighting via the balancer 6, even if only one discharge lamp causes half-wave discharge, there is another parallel discharge lamp circuit, so the inverter output will not be a complete half-wave, and the parallel lighting circuit will It is only necessary to consider the case where each discharge lamp discharges a half wave in the same direction (in Fig. 1, discharge lamps 7, 8, 10, 11
Since sequence inductors 13 to 16 are connected in parallel to , only if both discharge lamps 9 and 12 perform half-wave discharge in the same direction). Therefore, inductor 17 having a sufficiently larger inductance value than sequence inductors 13 to 16 may be connected in parallel to either discharge lamp 9 or 12.

Furthermore, considering the circuit shown in FIG. 1 in which the inductor 18 is omitted, if the discharge lamp 12 malfunctions or is removed for some reason, the inductor 17 will receive a high voltage due to the boosting effect of the balancer 6. However, if the inductor 18 is provided as shown in FIG. 1, this can be reduced.

Here, the reason for this will be explained. Inductor 17 in FIG. 1 is set to a larger inductance value than other sequence impedances (inductors 15, 16, etc.) in order to obtain a sequential lighting effect. Now, discharge lamps 7 to 9 are lighting normally, and assuming that discharge lamp 12 is removed, the inductance value is larger than that when discharge lamp 10 or 11 is removed. The voltage applied to the inductor 17 connected across the lamp 12 increases.

Moreover, a back electromotive force is generated in the balancer 6 due to the current flowing through the discharge lamps 7 to 9, and the balancer 6 acts as an autotransformer and is applied to the inductor 17 in a form that is added to the inverter output voltage.

For such a point, an inductor 1 is installed between the connection point of the discharge lamps 8 and 9 and the connection point of the discharge lamps 11 and 12.
By connecting 8, the above-mentioned high voltage is released through the discharge lamp 9, and application of the high voltage to the inductor 17 is suppressed.

Also, when any one of the discharge lamps 7 to 12 (for example, only discharge lamp 12) malfunctions, each inductor 1
The other discharge lamps 7 to 11 can be kept lit via the discharge lamps 3 to 18, and therefore, it also has the advantage of being able to immediately identify which discharge lamp has reached the end of its life.

In the conventional examples shown in Figures 2 to 4, each inductor is represented as a saturable inductor, but this means that when the discharge lamp load is removed or the lamp is turned off, the inverter output voltage (discharge This is a safety measure to prevent the voltage (voltage between the lamp connection terminals) from rising, and to reduce stress on the inverter. An inductor is also effective (reducing stress on the inverter circuit due to DC output components).

This invention refers to bypassing the DC component during half-wave discharge of some discharge lamps in a discharge lamp configuration in which multiple lamps are operated in series and parallel, and is not particularly limited to saturable reactors. Even if each inductor in this invention is a saturable reactor,
The effect is sufficiently obtained, and the inverter output voltage suppression when the discharge lamp is removed has the same effect as the conventional example (because it is the same as the conventional example, no mention is made of the saturable reactor).

[Effect of idea]

According to the discharge lamp lighting device of this invention, when lighting a plurality of discharge lamps at once by connecting a series circuit of a plurality of first and second discharge lamps to the output end of an inverter device via a balancer, A first inductor is connected in parallel to all discharge lamps except for one discharge lamp constituting a series circuit of a plurality of first discharge lamps, and an inverter in the series circuit of a first plurality of discharge lamps is The connection point between the discharge lamp closest to the other output terminal of the device and another discharge lamp adjacent to this discharge lamp, and the connection point closest to the other output terminal of the inverter device in the series circuit of the second plurality of discharge lamps. Because a second inductor is connected between the discharge lamp and the connection point with another discharge lamp adjacent to this discharge lamp, current will flow in both directions through the inductor even if one of the discharge lamps has a half-wave discharge. This reduces the stress applied to the inverter device, and since the voltage is shared between each inductor, high voltage is not applied to each inductor, each inductor can be small, and the stress reduction function can be fully demonstrated, and insulation breakdown can be reduced. No countermeasures are required and it is inexpensive.

In addition, the inductance value of one of the multiple inductors connected in parallel to each discharge lamp is set to be sufficiently larger than the inductance value of the remaining inductors, so at startup, the inductor with a relatively small inductance value is set as the sequence impedance. Furthermore, since the boosting effect of the balancer can be utilized, starting performance is extremely good even when series-parallel lighting is performed.

Furthermore, a connection point between the discharge lamp closest to the other output terminal of the inverter device in the series circuit of the first plurality of discharge lamps and another discharge lamp adjacent to this discharge lamp, and the second plurality of discharge lamps are connected to each other. A second inductor is connected between the discharge lamp closest to the other output terminal of the inverter device in the series circuit of and the connection point of another discharge lamp adjacent to this discharge lamp, and this second inductor Since the inductance value of is set to be approximately the same as the inductance value of all the remaining inductors among the plurality of first inductors, the other output terminal of the inverter device in the series circuit of the second plurality of discharge lamps. Even if the discharge lamp closest to the discharge lamp is removed, stress can be reduced by reducing the voltage applied to the inductor with a large inductance value connected in parallel to the discharge lamp.

Furthermore, even if any of the discharge lamps malfunctions, the remaining discharge lamps continue to be lit, so it is possible to immediately identify which discharge lamp has reached the end of its life.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a first embodiment of this invention, and FIGS. 2, 3, and 4 are circuit diagrams of conventional discharge lamp lighting devices, respectively. E...DC power supply, 5...Inverter device, 6...
...Balancer, 7-12...Discharge lamp, 13-17...
...Inductor.

Claims (1)

[Claims for Utility Model Registration] A DC power supply, an inverter device powered by the DC power supply, a balancer having a common terminal connected to one output end of the inverter device, a first individual terminal of the balancer, and the a first series circuit of a plurality of discharge lamps connected between the other output terminal of the inverter device; and a second series circuit connected between the second individual terminal of the balancer and the other output terminal of the inverter device. a series circuit of a plurality of discharge lamps, and the first and second plurality of discharge lamps excluding the discharge lamp closest to the other output terminal of the inverter device among the series circuit of the first plurality of discharge lamps. a plurality of first inductors each connected in parallel to all the discharge lamps in a series circuit of the first plurality of discharge lamps, and a discharge lamp closest to the other output terminal of the inverter device in the series circuit of the first plurality of discharge lamps; The connection point with another discharge lamp adjacent to this discharge lamp, the discharge lamp closest to the other output terminal of the inverter device in the series circuit of the second plurality of discharge lamps, and the other discharge lamp adjacent to this discharge lamp. a second inductor connected between a connection point with the discharge lamp, and a second inductor connected in parallel to the discharge lamp closest to the other output terminal of the inverter device in the series circuit of the second plurality of discharge lamps. The inductance value of the connected inductor is set to be sufficiently larger than the inductance value of all the remaining inductors among the plurality of first inductors, and the inductance value of the second inductor is set to be sufficiently larger than the inductance value of all the remaining inductors among the plurality of first inductors. The discharge lamp lighting device is set to have the same inductance value as all the remaining inductors inside the discharge lamp lighting device.