JPH0245317B2 - HODENTOHEIRETSUTATOTENTOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lighting device for multiple discharge lamps in parallel, which makes it possible to obtain stable operation regardless of fluctuations in the number of loaded lamps.

FIG. 1 shows a conventional discharge lamp lighting device. This is a series combination of the outputs of three sets of constant current push-pull inverters 2, 3, and 4 that input the voltage between each phase of a three-phase commercial power supply 1, and the combined output is connected to a current limiting impedance 5 and a discharge lamp 6 in series. This device lights a plurality of discharge lamps in addition to a parallel circuit of a plurality of lighting circuits including a series circuit of a circuit, a current limiting impedance 5', and a discharge lamp 6'. Note that the switching transistors 11 and 12 of the constant current push-pull inverter 2
Base terminals A and B are feedback transformer 1 for self-excited oscillation.
The same applies to the other inverters 3 and 4.

In operation, when the power supply 1 is turned on, the voltage between UV is full-wave rectified by the full-wave rectifier 7, and is converted into a switching element via the constant current inductor 8 and the primary winding 9a of the oscillation transformer 9. It is added to the collectors of transistors 11 and 12. At the same time, the transistors 11 and 12 are supplied with base current by the DC bias power supply 13 via the base resistors 14 and 15, but due to variations in the characteristics of the transistors, one of them turns on first, and this causes the oscillation transformer to An oscillating voltage is generated by the primary winding 9a and the oscillating capacitor 10. Similar operations are performed for the other inverters 3 and 4, and the oscillation transformers of each inverter 2, 3, and 4
Oscillating voltages v ₁ , v ₂ , and v ₃ are generated in the secondary windings, and these oscillating voltages are positively fed back to the transistor pair in each inverter by the secondary winding of the feedback transformer 16 for self-excited oscillation, causing oscillation. Start. Since each inverter oscillates in the same phase and these are superimposed in series at high frequency, the voltage applied to the discharge lamp has a nearly constant amplitude due to the property that the instantaneous power of three-phase AC is constant. High frequency voltage can be obtained.

Now, if we consider how the vibration period of each inverter is determined, the loads seen from the inverter 2 are the current limiting stations 5, 5', the discharge lamps 6, 6', and the inverters 3, 4. Therefore, the vibration period of the inverter 2 is determined by the combined impedance of the current limiting choke, the discharge lamp, and the inverter circuit, and if the number of discharge lamps increases or decreases, the vibration period of each inverter will naturally change, and as a result, the lighting The period of the output voltage v _put from device A will also change. The relationship between this period (frequency) change is as follows.

Decrease in the number of lights → increase in the cycle of v _put → decrease in the frequency of vout Also, when the number of lights increases, the opposite is true.

Currently, reactance elements with low power loss are used as the current limiting elements of the discharge lamps 6 and 6', so the current flowing through the current limiting elements depends on the frequency of the output voltage v _put . In the case of a discharge lamp, if the number of lamps decreases, the power consumption of the discharge lamp (hereinafter referred to as lamp power) increases in the case of parallel lighting of multiple lamps as shown in FIG. This means that the impedance of the current limiting chain is ωL (ω; the angular frequency of v _put ,
This problem arises because L is the inductance value of the chiyoke. However, if such a problem occurs, the lamp power will be output in excess of the rated value, leading to the deterioration of the life of the lamp itself, not only will it not be possible to obtain an appropriate illumination intensity, but also the safety of the lighting device will be compromised due to abnormal heat generation of the current limiter. There were also problems with sexuality.

In addition, if the current limiting element is a capacitive capacitor, the impedance is given by 1/ωC, so there is no above disadvantage, but if the number of loaded lamps decreases, the lamp power will be reduced below the rated value, and in the case of thinning lighting. The problem was that the illuminance did not reach the expected illuminance, making it difficult to obtain an appropriate lighting environment.

The present invention was proposed in view of the above-mentioned points, and the voltage between each phase of a three-phase commercial power supply is full-wave rectified to provide a circuit power supply, and the outputs of three sets of high-frequency conversion inverters having a vibration system are serially synthesized. In a lighting device for multiple discharge lamps that uses the combined output to light multiple discharge lamps at a nearly constant level of high frequency, it reduces lamp current fluctuations caused by fluctuations in the output voltage frequency when the number of load lamps changes. However, it is an object of the present invention to provide a practical and highly reliable discharge lamp lighting device that is not limited to the number of load lamps as a lighting device for multiple lights.

Hereinafter, the present invention will be described in detail with reference to the drawings showing examples.

FIG. 2 shows a first embodiment of the present invention, and the same parts as in the conventional example shown in FIG. 1 are given the same reference numerals. To explain the configuration in the figure, each line voltage u-v, v- of the three-phase commercial power supply 1 is
w and w-u are respectively connected to the AC input terminals of full-wave rectifiers provided at the input stages of three sets of constant current push-pull inverters (hereinafter simply referred to as inverters) 2, 3, and 4. are configured identically. To explain the internal configuration of the inverter 2, the positive DC output end of the full-wave rectifier 7 is connected to the midpoint of the primary winding of the oscillation transformer 9 via the constant current choke 8, and both ends of the primary winding are The collectors of transistors 11 and 12 are connected by a capacitor 10 and serve as switching elements.
It is connected to the negative side DC output end of the full-wave rectifier via an emitter. In addition, the transistor 11,
Base resistors 14 and 15 are connected between both bases of transistor 12, and a DC bias power supply 13 is connected between the connection point of resistors 14 and 15 and the emitters of both transistors with the base side being positive. On the other hand, 2 of the oscillation transformers 9, 9', 9'' of each inverter 2, 3, 4
The secondary windings are connected in series with each other and taken out as the output of the lighting device A, and are also connected to the primary winding of the feedback transformer 16 for self-excited oscillation, and the three sets of secondary windings are not shown in the figure. Connected between the bases of the transistor pair within each inverter. Then,
A plurality of lighting circuits each including a discharge lamp and a current-limiting element provided individually are connected in parallel to the output end of the lighting device A via a current-limiting impedance element 17 in series.

By the way, the drawback of the conventional example is that the vibration period of the three sets of inverters constituting the lighting device A depends on the load impedance (Z _L ) seen from the lighting device A. Therefore, in the present invention, by reducing the dependence of the load impedance (Z _L ) on the number of load lamps, frequency fluctuations in the output voltage v _put due to fluctuations in the number of lamps are reduced.

Now, in Fig. 2, the impedance of the series circuit consisting of the discharge lamp 6 and the current limiting element ₅ is Z0, the impedance of the current limiting impedance element inserted in series at the output end is _Z1 , and the number of circuits connected in parallel is n. Then, the load side impedance Z _L is expressed by the following formula Z _L = Z ₁ + (1/n) Z ₀ . What this formula means is that the load impedance Z _L is the impedance Z ₁ of the current limiting impedance element 17 inserted in series at the output end,
Impedance of series circuit with discharge lamp and current limiting element
Although it is related to Z ₀ , its dependence on the number of lights n is reduced by the constant term Z ₁ compared to the conventional case. Therefore, current-limiting impedance element 1
By selecting an appropriate value for 7, it is possible to make the fluctuations in the actual load impedance Z _L extremely small, thereby reducing the frequency fluctuations and keeping the lamp power per discharge lamp constant. Can be done. Note that the operation of the inverter is the same as in the conventional example, and its explanation will be omitted.

FIG. 3 shows a second embodiment, in which a compensation impedance element 18 is connected in parallel between the output terminals of the lighting device A in place of the current-limiting impedance element 17 of the first embodiment, and other The configuration is the same.

Expressing the load impedance Z _L in this case as an equation, where Z ₁ is the impedance of the compensation impedance element 18, Z ₀ is the series impedance of the current limiting element 5 and discharge lamp 6, and n is the number of lamps, Z _L = 1/ (1/Z ₁ +n/Z ₀ ), and the load impedance is as in the first embodiment.
This shows that the dependence of Z _L on the number n of lights is reduced compared to the conventional example.

In addition, in the first and second embodiments described above, a plurality of discharge lamps connected to one current limiting element are connected in parallel, but the present invention is not limited to this, and two or more lamps are used. There is no problem even if the two are connected in parallel.

As described above, in the parallel multiple discharge lamp lighting device of the present invention, each output of the oscillation transformer of the three sets of constant current push-pull inverters inputs the full-wave rectified line voltage of the three-phase commercial power supply. In a device for lighting a discharge lamp by connecting side secondary windings in series and connecting in parallel a plurality of series circuits each including a discharge lamp and a current limiting element of each discharge lamp to the series connection circuit, the plurality of discharge lamps and By connecting a current-limiting impedance element or a compensation impedance element in series or parallel to the parallel circuit of the series circuit made up of the current-limiting elements of each discharge lamp to reduce oscillation frequency fluctuations due to load fluctuations, the design of the lighting device is improved. It is not limited by the number of load lamps, and therefore it becomes easy to design lighting to obtain illuminance depending on the place using the same lighting device. For example, even if the lighting intensity was originally designed to use 10 lights, but the user wishes to increase the lighting to 6 lights, there is no need to change the equipment at all, and it is possible to respond to thinned-out lighting.

(b) Even if the above-mentioned reduced lighting is performed, abnormal heat generation does not occur, and safety is ensured.

C. It has versatility as a lighting device for multiple lights, and can be expected to reduce costs through mass production.

There are advantages such as

[Brief explanation of the drawing]

Figure 1 shows an example of the circuit of a conventional discharge lamp lighting device.
3 are circuit diagrams showing first and second embodiments of the present invention. A...Lighting device main body, 1...3-phase commercial power supply,
2, 3, 4... Inverter, 17... Current limiting impedance element, 18... Compensation impedance element, 6, 6', 6"... Discharge lamp, 5, 5', 5"...
Current limiting element.

Claims (1)

[Scope of Claims] 1. The secondary windings of the output sides of the oscillation transformers of three sets of constant current push-pull inverters that receive full-wave rectification of each line voltage of a three-phase commercial power source are connected in series, and the In a device for lighting a discharge lamp by connecting in parallel a plurality of series circuits each including a discharge lamp and current-limiting elements of the individual discharge lamps in a connected circuit, A lighting device for multiple discharge lamps in parallel, characterized in that a current-limiting impedance element is connected in series with a parallel circuit. 2 The secondary windings on the output side of the oscillation transformers of three sets of constant current push-pull inverters that input full-wave rectification of each line voltage of a three-phase commercial power supply are connected in series, and a discharge lamp and a In a device for lighting a discharge lamp by connecting a plurality of series circuits of current-limiting elements of individual discharge lamps in parallel, in parallel with a parallel circuit of the series circuits of the plurality of discharge lamps and current-limiting elements of the individual discharge lamps, A lighting device for multiple discharge lamps in parallel, characterized in that a compensating impedance element is connected.