JPS59149697A - Device for firing discharge lamp - 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 [Technical Field] The present invention relates to a discharge lamp lighting device that lights a discharge lamp at high frequency using an inverter output and also dims the discharge lamp in steps.

[Background technology]

Figure 1 shows an example of a conventional circuit, and Figure 2 is a circuit diagram of its main parts. , these constitute a DC power supply (a). ([]) is a constant current push-pull type inverter with choke coils (4
), output trasis for oscillation (5), and capacitor (6
), a switching transistor +7) (8), and a base resistor (9) [10), and aυ is an auxiliary power supply, consisting of a diode αη and a capacitor +j (2), and its output In addition to driving the bases of the switching transistors (7) and (8), it also drives a timer circuit (to) that controls a starting switch (c), which will be described later. Q←
The outputs of these preheating transformers θ~(g) are the respective terminals a- of the filaments of the discharge lamps (hereinafter referred to as lamps) @~(c), which are similar to fluorescent lamps. ”-e. Also, the a samurai has a choke coil installed as a current reducing interface,
I2I is a capacitor for noise prevention, ψ is a choke coil provided as a parancer, and @ is a dimming switch.

Therefore, in the conventional example circuit shown in FIG. 1, the commercial power supply (1
) is turned on, the rectifier bridge (2) and capacitor (3) form a DC power supply (a), and the choke coil (4), output transformer (5), resonance capacitor (6)) and the switch inter transistor (7) Drives a constant current type inverter (0) consisting of a +8+ and a base resistor (9+ (10). Here, an auxiliary power supply (0) consisting of a diode (11) and a capacitor 2) is driven.
The inverter (0) drives the base of the switching transistor (7+ (8)).The harmonic output of this inverter (0) appears at the 21st winding N2 of the output transformer (5). If the starting switch (c) is turned on by the timer circuit (13) for a period of seconds, the in7S - evening output will be supplied to the starting switch (e) and the preheating transformer to the circuit (g). , the lamp (A) connected to the secondary side of the preheating transformer α→～ (to)
~(c) Preheat each filament. Here, since the preheating transformer α→~(to) has a relatively low impedance, when the starting switch (a) is turned on, no lighting voltage is applied to the lamps (a) to (c), and only preheating is performed. . After about 1 second, the starting switch (c) is turned off, and the high frequency power of the p1 input 7S-ta ([]) is applied to the terminal (c), which turns on the light. In this case, the dimmer switch is turned off. ) is on the NC contact side, it is fully lit, and when it is on the NO contact side, it is dimmed.When dimmed, the preheating transformer α→～
Because current flows through (to), the lamp filament is constantly preheated. Note that the capacitor wH is a capacitor for reducing radiation noise during dimming lighting.

Is Fig. 2 a circuit diagram of only the preheating circuit of the conventional circuit shown in Fig. 1? When the starting switch @ is turned on, the current flowing through the starting switch (a) is lo, the current flowing to the negative side of the preheating transformer αΦ~(g) is 11, and the current flowing through the dimmer switch is 11. ) is 12, then
The circuit of FIG. 2 operates as follows. In other words, when the dimmer switch) is on the NO contact side, 12=0, l
0=1. All the current flowing through the starting switch (c) flows into the preheating transformer αΦ~(g) and preheats the filament, but when the dimmer switch (a) is on the NC contact side, I, = Io - I, Therefore, when the dimmer switch (a) is on the NO contact side, the current flowing into the preheating transformer α→~Q81 decreases, and therefore the preheating current also decreases. this is,
This means that the preheating current during dimming lighting is large and the preheating current during full lighting is small, which can be said to be preferable in consideration of dimming starting. However, if the difference in preheating and heat reduction becomes large, for example, if the preheating current during full lighting is designed to an optimal value, the preheating current during dimming will become too large, which will have a negative impact on the lamp life. Or, conversely, if the preheating current during dimmed lighting is designed to the optimum value, the preheating current during full lighting will decrease, which may result in poor starting performance and adversely affect lamp life. There was a problem.

[Purpose of the invention]

The present invention provides a discharge lamp lighting device having means for lighting a discharge lamp at high frequency using an inverter output and for stepwise dimming of the discharge lamp. It is an object of the present invention to provide a discharge lamp lighting device which compensates for the difference in the amount of light by an easy method, improves the life of the lamp, and further reduces radiation noise during dimming.

[Disclosure of the invention]

FIG. 8 shows an overall circuit diagram of an embodiment of the present invention, and FIG. 4 shows a main part circuit diagram of the same. In contrast to the circuit of the conventional example shown in FIG.
A capacitor (A) for preheating current compensation and radiation noise reduction is connected in parallel to the choke coil Q, which is the current reducing interface.
The difference is that they are connected. However, in the circuits of Fig. 8 and Fig. 4, when the starting switch (a) is turned on, the current flowing through the starting switch (a) is 16,
Current flowing to the negative side of preheating transformer q~(g) 16
．． Furthermore, if the current flowing through the dimmer switch (A) is l/, then when the dimmer switch (A) is on the NC contact side, I'2 = 0, 16 = 11, and the current flows through the starting switch. ) All the current flowing through the preheating transformer α41/- (to)
When the dimmer switch (A) is on the NC contact side, it is I', and when the dimmer switch (A) is on the NC contact side, it is I', and when the dimmer switch (A) is on the NC contact side, The current flowing into the preheating transition α→^ (to) decreases, and therefore the preheating current also decreases. Comparing with the conventional examples shown in Figs. 1 and 2, if loξl'o is the dimmer switch (
When A) is on the NC contact side, the current ■1 is i'+>i,
(or It<1g). Therefore, it is possible to improve various problems in the conventional example due to the large amount of preheating current during dim lighting and the small amount of preheating current during full lighting. In other words, compared to the impedance of the choke coil (1'I) which is the impedance for current reduction, the impedance of the parallel circuit of this choke coil α and the capacitor (c) is larger, so naturally the current flow '2 decreases. However, since the degree of this reduction is almost determined by the capacitance of the capacitor ■,
This makes it possible to reduce the difference in starting preheating current when dimming and when fully lit. On the other hand, after the dimming is turned on, the starting switch (c) is off, and the dimming switch (goods) is on the NC contact side.
The output drance (5
) A capacitor wire is connected between the secondary windings of the output transformer (5), which has the effect of reducing radiation noise due to harmonic components contained in the output voltage of the output transformer (5), as shown in Figures 8 and 4. In the configuration of the present invention, the above-mentioned capacitor wire and]
A synergistic effect with radial noise + j (c) appears and radiation noise can be further reduced.

〔Effect of the invention〕

Since the present invention is configured as described above, in the conventional circuit, the starting preheating current in the dimming state was too large compared to the starting preheating current in the full lighting state, or the starting preheating current in the full lighting state was too large. It has the effect of eliminating the negative effects on lamp life and startability that occur when the starting preheating current in dimming mode is too small by simply adding a ■＠ capacitor. In addition, it is possible to obtain the effect that radiation noise during dimming lighting can be further reduced to a large extent.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional example, Figure 2 is a circuit diagram of the same main part as above,
Fig. 8 is a circuit diagram of an embodiment of the present invention, and Fig. 4 is a circuit diagram of the same essential parts, in which +1) is an AC power supply, (5) is an output trasys, and (7) and (8) are respectively transistor, a
Φ ~ (to) is the preheating trasis, near 0 is the choke coil which is the interface for current reduction, 翺 is the capacitor, @/-(
C) is a lamp (discharge lamp), (E) is a starting switch, (A) is a dimming switch, and (C) is a capacitor. Agent Patent Attorney Ishi 1) Choshichi

Claims (1)

[Claims] (1) A self-excited inverter that is energized by a DC output obtained by rectifying or rectifying and smoothing an AC power supply and generates a high-frequency output in the output transformer secondary winding by on/off control of a switching transistor. This inno'
+ - A plurality of discharge lamps connected to the output side of the output side and lit at high frequency; a current reducing intertatsis and a preheating transformer for preheating the discharge lamp filament, which are connected in series to the discharge lamps with respect to the output transformer secondary winding; , a starting switch connected between one end of the output transformer secondary winding that is not connected to the preheating trasis and a connection point of the flow reducing intufftance and the preheating transformer, and a series connection between the preheating transformer and the flow reducing intufftance. a dimmer switch connected in parallel to the circuit; a capacitor for reducing radiated noise connected between the secondary windings of the output transformer only when dimming with the dimmer switch; A discharge lamp lighting device comprising a capacitor connected in parallel.