JPS593897A - Multiple parallel discharge lamp firing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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.

Figure 1 shows a conventional discharge lamp lighting device. This combines the outputs of three sets of constant current push-pull inverters 2, 3 and 4 into which the inter-phase voltages of the 3-phase commercial power supply 1 are inputted in series, and the combined output is converted into a current-limiting impedance 5. This device lights a plurality of discharge lamps in addition to a parallel circuit of a plurality of lighting circuits, such as a series circuit of discharge lamps 6, a current limiting impedance 5', and a series circuit of discharge lamps 6'. Note that the base terminals 41 of the switching 1 to transistors 11.12 of the constant current push-pull inverter 2 are connected to both ends of the secondary winding of the feedback transformer 16 for self-excited oscillation, and the same applies to the other inverters 3.4. It is.

In operation, when the power supply 1 is turned on, the full-wave rectifier 7
The voltage between the two voltages is full-wave rectified and applied to the collector of the transistor 11.12 as a switching element via the constant current inductor 8 and the primary winding 19a of the oscillation transformer 9. At the same time, the base current is supplied to the J transistors 11 and 12 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, causing oscillation. An oscillating voltage is generated by the primary winding 9a of the transformer 9 and the oscillating capacitor 10. Other inverters 3.4
A similar operation is performed for each inverter 2, 3゜4, and the secondary windings of the oscillation transformers have vI, V2 + v
3 oscillating voltage is generated, and the self-oscillation feedback transformer 16
These oscillating voltages are positively fed back to the transistor pair in each inverter by the secondary winding of the inverter to start oscillation. 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, considering how the vibration period of each inverter is determined, the loads seen from the inverter 2 are the current limiting choke 5.5', the discharge lamp 6.6', and the inverter 3.4. Therefore, the vibration period of inverter 2 is a current-limiting joke and a discharge lamp.

It is determined by the combined impedance of the inverter circuit, and as the number of discharge lamps increases or decreases, the vibration period of each inverter will naturally change, and as a result, the period of the output voltage Vnll from lighting device A will also change. . The relationship between this period (frequency) change is as follows.

Decrease in number of lights → Increase in cycle of V[lll → Decrease in frequency of V[lll. Also, when the number of lights increases, the opposite is true.

Now, since reactance elements with low power loss are used as current-limiting elements of the discharge lamps 6, 6', the current flowing through the current-limiting elements depends on the frequency of the output voltage VOIII.
When the current-limiting element is a current-limiting choke, if the number of lamps decreases, in the case of the parallel multiple lamps shown in Figure 1, the power consumption of the discharge lamp (hereinafter referred to as lamp power horn) increases. This means that the impedance of the current limiting choke is ωL (ω* V 0L
This problem arises because the angular frequency is given by the angular frequency of II, L: the inductance value of the choke. However, if such a problem occurs, the lamp power will be output above the rated value, and
This not only shortens the lifespan of the lamp itself, but also makes it impossible to obtain adequate illuminance, and also poses safety problems as a lighting device due to abnormal heat generation in the current limiting choke.

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 illuminance did not reach the expected level of illumination, making it difficult to find an appropriate lighting environment.

The present invention has been 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,
A practical and highly reliable discharge lamp that reduces lamp current fluctuations caused by fluctuations in the output voltage frequency when the number of load lamps changes, and can be used as a lighting device for multiple lamps without being limited by the number of load lamps. The purpose is to play chess with a revision device.

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 uv, vw of the three-phase commercial power supply 1.

W-U consists of three sets of constant current push-pull inverters (hereinafter referred to as
(simply referred to as an inverter) 2.3.4 are connected to the AC input terminals of a full-wave rectifier provided at the input stage,
Each inverter is 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 oscillating transformer b through the constant current choke 8.
It is connected to the midpoint of the next winding, and both ends of this primary winding are connected by a capacitor 10, and the negative side DC current of the full-wave rectifier is passed through the collector and emitter of transistors 11 and 12 as switching elements. Connected to the output end. Further, a pace resistor 14.15 is connected between both bases of the transistors 11.12, and a DC bias current [
13 are connected with the base side facing forward.

On the other hand, the oscillation transformer 9°91 of each inverter 2, 3.4
．． The secondary windings of 911 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 lance 16 for self-excited oscillation, and the three sets of secondary windings are not shown in the figure. Although not connected between the bases of the transistor pair within each inverter. Next, to the output end of the lighting device A, a plurality of redundant circuits each including a discharge lamp and a current-limiting element provided individually are connected in parallel through 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 (ZL) seen from the lighting device A. Therefore, in the present invention, by reducing the dependence of the load impedance (7L) on the number of load lamps, frequency fluctuations in the output voltage t111 due to fluctuations in the number of lamps are reduced.

Now, in FIG. 2, if the impedance of the series circuit consisting of the discharge lamp 6 and the current limiting element 5 is Zo, the impedance of the current limiting impedance element inserted in series at the output end is Z11, and the number of circuits connected in parallel is n, then The load side impedance ZL is expressed by the following formula 2 (%). What this formula means is that although the load impedance ZL is related to the impedance Z1 of the current limiting impedance element 17 inserted in series at the output end and the impedance 7o of the series circuit of discharge lamps and current limiting elements, the number of lamps Compared to the conventional case, the dependence on n is a constant term Z,
This means that it is reduced by the same amount. Therefore, by selecting an appropriate value for the current-limiting impedance element 11, it is possible to make the fluctuations in the actual load impedance ZL extremely small, and therefore the frequency fluctuations are also small, and the lamp speed per discharge lamp is reduced. Power can be kept constant. Note that since there is no difference in the operation of the inverter from the conventional example, a description thereof 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 ZL in this case, the impedance of the compensation impedance element 18 can be expressed as Z+
, the series impedance of the current limiting element 5 and the discharge lamp 6 is Z
o, and the number of lights is n, then ZL = 1/ (1, /-Z+
+n/Zo), indicating that the dependence of the load impedance Z on the number n of lamps is reduced compared to the conventional example, as in the first embodiment.

In addition, the above 1. In the second embodiment, a plurality of discharge lamps connected to one current-limiting element are connected in parallel, but the invention is not limited to this, and two or more lamps connected in parallel are used. There is no problem in connecting it.

As described above, in the parallel multiple discharge lamp lighting device of the present invention, each output side 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 secondary windings in series and connecting in parallel a plurality of series circuits each including a discharge lamp and current-limiting elements of the individual discharge lamps to the series connection circuit, the plurality of discharge lamps and the individual By connecting a current-limiting impedance element or a compensation impedance element in series or parallel to the parallel circuit of the series circuit of the current-limiting element of the discharge lamp, the oscillation frequency fluctuation due to load fluctuation can be reduced. is not limited by the number of load lamps, and therefore it is easy to design lighting to obtain illuminance depending on the location using the same lighting device. For example, even if the lighting illuminance was originally designed to use 10 lights, but the user wishes to increase the number to 6 lights, there is no need to change the device at all, and it is possible to respond to thinned-out lighting.

Low: Even if the above-mentioned thinned-out 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 cost by 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, Figures 2 and 3
The figure is part 1 of the present invention. FIG. 3 is a circuit diagram showing a second embodiment. A: Lighting device 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 patent applicant Matsushita Electric Works Co., Ltd.

Claims (3)

[Claims] (1) The secondary windings on the output side of the oscillation transformers of three sets of constant current push-pull inverters, which input full-wave rectification of each line voltage of a three-phase commercial power supply, are connected in series, and the series connection circuit is connected to a discharge lamp. and a device for lighting a discharge lamp by connecting a plurality of series circuits made up of current-limiting elements of individual discharge lamps in parallel; 1. A parallel multiple discharge lamp lighting device, characterized in that a limiting impedance element or a compensating impedance element is connected in parallel. (2) The discharge lamp parallel multi-pair lighting device according to claim 1, wherein the current limiting impedance element is an inductance element. (3) The parallel multiple discharge lamp lighting device according to claim 1, wherein the compensating impedance element is a capacitor.