JPS602758B2 - Discharge lamp lighting circuit for two lamps - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lighting circuit for a two-lamp discharge lamp, and an object of the present invention is to provide a lighting circuit that is small and lightweight, has low power loss, is inexpensive, and is capable of flickerless lighting.

There is an LC series type hybrid lighting circuit as a conventional discharge lamp lighting circuit, but its basic circuit is shown in Figure 4. Even if the power supply voltage V^c is about the same as the lamp voltage VI, it cannot be boosted by a normal transformer or other means. It is characterized by the fact that it can be lit directly without going through a circuit, making it possible to obtain a compact, lightweight, low power loss, and inexpensive lighting circuit.

For example, a 40W poppy lamp with a lamp voltage of about 105V can be lit directly from an AC power source of 100V. However, in addition to single lamp lamps, lamps for two lamps, which are extremely commonly used, require an increase in electric power, and are often used from AC 200V power sources rather than AC 100V. In this case, if two lamps are connected in series and lit as shown in Fig. 5, it is essentially the same as a single lamp with double the lamp voltage, and it can be designed and lit in the same way as shown in Fig. 4. can. However, since the voltage as a whole is doubled, the voltage of the inductance element L, the voltage of the capacitor C, and the voltage of the semiconductor switch element S must all be made to withstand voltages that are more than twice as high. is damaged. Generally, the cost of an inductance element is proportional to VA (VA: inductance capacity), the cost of a capacitor is proportional to CV2 (C: capacitance, V: voltage), and the cost of a semiconductor is proportional to Vn (n21). If two 40W fluorescent lamps are connected in series and lit at 200V AC, the inductance element will be doubled, and the capacitor will have C of 1'2 and V of twice as much, so the cost will be approximately doubled. If n=2, the semiconductor will become 4 times as large.
At best, it will be twice as long as for one light. The present invention was devised in consideration of the above points, and is a 4-inch, lightweight, low-loss discharge lamp lighting circuit for two lamps that is less than twice the cost of a single lamp and provides a flickerless effect. This will be explained in detail below using Examples. FIG. 1 shows a basic circuit of the present invention, in which a series circuit of a first inductance element 2, a capacitor 3, and a first discharge lamp 4 is connected to an AC power supply 1, and a second inductance element 5 is connected in parallel to the capacitor 3. and second
The discharge lamps 6 connected in series are connected, and the semiconductor switch element 7 is connected in parallel to the first discharge lamp 4.

This will be explained with reference to the specific circuit shown in FIG. 2 using a poppy lamp as an example, and FIG. 3 showing its operating waveforms. In Fig. 2, 8 is a triac, 9 is a constant phase ignition circuit, and when the triac 8 is turned on, the child heat is transferred to the first inductance element 2 and the capacitor 3.
and the LC series oscillating current of the triac 8.

As a result, charge is accumulated in the capacitor 3, and the first discharge lamp 4 is started by the superimposed voltage of the power supply 1 and the capacitor 3.
On the other hand, the second discharge lamp 6 is started directly by the capacitor 3. Thus, both discharge lamps 4 and 6 are lit. The first discharge lamp 4 now obtains approximately the same operating mode as would be obtained when the supply voltage V, of the power supply 1 is approximately equal to the lamp voltage, and its lamp current 14 (shown by diagonal lines in FIG. 3b) has a leading phase with respect to the power supply voltage V shown in FIG. 3a. In Fig. 3b, with a current of 1 G flowing through the triac 8,
The lamp is ignited at a predetermined phase by the constant phase ignition circuit 9 and conductive, and at this time the lamp current 14 becomes zero. FIG. 3c shows the lamp voltage V4 of the first discharge lamp 4. on the other hand,
The voltage V3 between the terminals of the capacitor 3 has a phase lag with respect to the power supply voltage V, as shown in FIG. The phase is delayed with respect to the terminal voltage V3. FIG. 3f shows the voltage waveform of the lamp voltage V6 of the second discharge lamp 6. In this way, since the current phases of both discharge lamps 4 and 6 are shifted by about 900 degrees, their respective light outputs when lit are as shown in Figure 3g, and the combined output of both discharge lamps 4 and 6 is as shown in Figure 3. It will look like h. In other words, if there is only one light, flicker of 100Hz to 120Hz will occur with commercial power supply, but according to this embodiment, the lighting light output is 200Hz.
HZ or about 240 days, and the flicker rate is also reduced, so lighting is virtually flickerless to the human eye. The lighting circuit shown in Fig. 4 is a distinctive lighting circuit in which current-limiting elements such as inductance elements and capacitors are small when the power supply voltage and lamp voltage are approximately the same.
If the power supply voltage is sufficiently higher than the lamp voltage, for example about twice, then the inductance should be doubled and the capacitor should be 1.
'2 gives the same three lamp currents and power, but the power factor becomes extremely low and the voltage of the current limiting element and control element doubles. Here, in order to improve the power factor and lower the capacitor voltage, it is effective to insert a resistive impedance Z in parallel to the capacitor C as shown in FIG. In the fourth invention, a second inductance element 5 and a second discharge lamp 6 are connected to this resistive impedance Z, and the lamp can be lit very effectively without wasting power. can. The voltage vectors of each part of the circuit of FIG. 1 and the circuit of FIG. 5 are as shown in FIG. 7 and FIG. 8, respectively. In other words, the current flowing through the discharge lamp 4 is slightly advanced in phase with respect to the voltage V^c (V,) of the AC power supply 1, as shown by 14 in FIG. 3, and the current 14 and the lamp voltage V1,
Since (V4) are substantially in phase, the vector phase relationship of the lamp voltages V1 and (V4) with respect to the power supply voltage V^c (V,) is as shown in FIG. In other words, lamp voltage V1, (V4)
is advanced in phase with respect to the power supply voltage V^c (V,). On the other hand, since the current flowing through the inductance element 2 and the current 14 are in phase, the voltage VL across the inductance element 2 is 90 degrees behind the current 14 in phase. (V,=Ldi no d
t) Therefore, the voltage VL, lags the lamp voltage V1, by 900, and is shown in the evening as shown in FIG. Further, the voltage Vc of the capacitor 3 naturally has a vector phase from the voltage VL, to the power supply voltage V^c (V,), as shown in FIG. Note that since a resistive (inductance element 5 and discharge lamp 6) impedance (inductance element 5 and discharge lamp 6) is connected in parallel with the capacitor 3, a resistive impedance (with a slightly delayed phase due to the presence of the inductance element 5) is connected, so the relationship in the case of no such impedance is shown in Fig. 8. The phase is slightly behind the voltage Vc (but leads as a whole). Furthermore, the phase relationship between the inductance element 5 and the discharge lamp 6 with respect to the capacitor 3 is that the inductance element 5 is inductive with a lag of 90o, and the discharge lamp 6 is almost resistive. As a result, the deviation becomes as shown in Fig. 7. Now, in the circuit shown in Figure 5, L+C
is capacitive as a whole, so the input current (or lamp current) slightly advances in phase with respect to the current voltage V^c (V,), and therefore the lamp voltage VI also leads with respect to the power supply voltage V^c (V,). The phase advances a little, and naturally (Vc+VL) is n and VI
The phase is delayed by 90 degrees with respect to the current, and becomes a vector connecting the tip of VI to the tip of the power supply voltage V^c (V,), as shown in FIG. As a result, Vc in Figure 1 becomes smaller, and V
There is not much difference between L and (VL, 10VL2). therefore,
The configuration shown in FIG. 1 reduces costs and makes the entire device smaller and lighter. The present invention connects a series circuit of a first inductance element, a capacitor, and a first discharge lamp to an AC power source, and connects a series circuit of a second inductance element and a second discharge lamp in parallel to the capacitor. and connecting a semiconductor switch element in parallel to the first discharge lamp,
Since the semiconductor switching element is conductive for a predetermined phase period in the second half of each half cycle of the AC power supply, the voltage applied to the capacitor and the semiconductor switching element can be lowered and the cost can be reduced. Moreover, the device is small, lightweight, and has low loss. In addition, it has the effect of providing flickerless lighting.

[Brief explanation of the drawing]

Fig. 1 is a basic circuit diagram of the dual discharge lamp lighting circuit of the present invention, Fig. 2 is a specific circuit diagram of the same embodiment as above, Fig. 3 a to h are operational waveform diagrams of the same as above, and Fig. 4 is a conventional circuit diagram. A basic circuit diagram of a discharge lamp lighting circuit, Fig. 5 is a basic circuit diagram for lighting the same two lamps as above, Fig. 6 is a diagram explaining the principle of the present invention, Fig. 7 is a voltage vector diagram of Fig. 1, and Fig. 8 is a basic circuit diagram of a discharge lamp lighting circuit. is the voltage vector diagram of FIG. 1... Power supply, 2... First inductance element, 3...
...Capacitor, 4...First discharge lamp, 5
. . . Second inductance element, 6 . . . Second discharge lamp, 7 . . . Semiconductor switch element. Figure 1 Figure 2 Figure 4 Figure 5 Figure 3 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. Connect a series circuit of a first inductance element, a capacitor, and a first discharge lamp to an AC power source, connect a series circuit of a second inductance element and a second discharge lamp in parallel to the capacitor, and A discharge lamp lighting circuit for two lamps, characterized in that a semiconductor switch element is connected in parallel to a first discharge lamp, and the semiconductor switch element is made conductive for a predetermined phase period in the second half of each half cycle of an AC power source.