JPS602759B2 - Discharge lamp lighting circuit for two lamps - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a discharge lamp lighting circuit for two lamps, and an object of the present invention is to provide a discharge lamp lighting circuit for two lamps that is small, lightweight, has low power loss, and is inexpensive. be.

ZAs a conventional discharge lamp lighting circuit, there is an LC series type hybrid 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 controlled by a normal transformer or other device. Can be lit directly without step-up, small size, light weight, low power loss, 2
It has the characteristic that an inexpensive lighting circuit can be obtained. 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, two-lamp lamps, which are extremely frequently 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 lit in series as shown in FIG. 5, it is essentially the same as one lamp with twice the lamp voltage, and it can be designed and lit in the same manner as shown in FIG. 4. However, since the voltage as a whole is twice as high, the voltage of the inductance element L, the voltage of the capacitor C, and the voltage of the semiconductor switch element S must all have a withstand voltage that is more than twice as high, which increases the cost of using two lamps. Benefits are lost. Generally, the cost of an inductance element is VA (V
A: Inductance capacity), capacitor cost is CV
2 (C: capacitance, V: voltage), and the cost of semiconductors is proportional to Vn (n21), so AC 20
40W from 0V, when two light lamps are connected in series and turned on, the inductance element is doubled and the capacitor C is 1.
'2, since V doubles, its cost approximately doubles,
If n=1, the number of semiconductors will be doubled, and at best it will be twice that for one lamp. The present invention was developed in consideration of the above points, and provides a discharge lamp lighting circuit for two lamps that is compact, lightweight, and has low loss while reducing the cost to less than twice that of a single lamp lamp and achieving a flicker-free effect. This will be explained in detail below using Examples.

FIG. 1 shows the basic circuit of the present invention, which includes an AC power source 1, a first inductance element 2, a capacitor 3, and a first discharge lamp 4.
A series circuit of the second inductance element 5 and the second discharge lamp 6 is connected in parallel to the series circuit of the capacitor 3 and the first discharge lamp 4, and a series circuit of the second discharge lamp 6 is connected in parallel to the series circuit of the capacitor 3 and the first discharge lamp 4. A semiconductor switch element 7 is connected in parallel to the lamp 4.

This will be explained with reference to the specific circuit shown in FIG. 2, taking a light 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 triac 8 is turned on, child heating is performed by the LC series oscillating current of the first inductance element 2, capacitor 3, and triac 8 from power supply 1. 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.

In this case, the triac 8 is turned on for a fixed phase period in the latter half of each half cycle of the power supply 1, and by forced resonance with the inductance element 2 and the capacitor 3, the triac 8 stores energy in the capacitor 3, and the discharge lamp 4 in the next half cycle.
The continuous lighting is stable. In other words, triac 8
functions as a switching element for voltage boosting and energy storage. On the other hand, the second discharge lamp 6 is started directly from the power source 1. Thus, both discharge lamps are lit. Next, the operation and operation waveforms of each part during lighting are shown. The first discharge lamp 4 is powered by the power supply voltage V. Approximately the same mode of operation is obtained when V. is approximately equal to the lamp voltage, and the lamp current L (shown with diagonal lines in FIG. 3b) is varied when the supply voltage V. is approximately equal to the lamp voltage. The phase advances with respect to 13 in Figure 3b
Reference numeral 2 indicates a current flowing through the capacitor 3, and 18 indicates a current flowing through the triac 8, which are ignited at a predetermined phase by a constant phase ignition circuit 9 and conductive. At this time, the lamp current 14 is zero. FIG. 3c shows the lamp voltage V4 of the first discharge lamp 4. On the other hand, the voltage V3 across the two capacitors 3 has a lagging phase with respect to the power supply voltage V, as shown in FIG.
The voltage across the series circuit with V, 8, that is, the input voltage V,8 of the second discharge lamp 6 has a phase lag of three with respect to the power supply voltage V, as shown in FIG. 3e. In this way, the lamp current 16 of the second discharge lamp 6 has a lagging phase with respect to the power supply voltage V. Third
Figure g shows the voltage waveform of the lamp voltage V6 of the second discharge lamp 6, and Figure h' shows the current waveform of the power supply current 1. that's all,
As can be seen from FIGS. 3b to 3f, the current phases of the three discharge lamps 4 and 6 are shifted by about 90 degrees from each other, so if only one lamp is used, flicker of 100Hz to 120Hz will occur with the commercial power supply, but this embodiment And, the combined light output of the first discharge lamp 4 and the second discharge lamp 6 blinks at 200Hz to 240Hz.
Since it becomes about HZ and the frit power factor also decreases, lighting becomes practically fritless to the human eye. Now, if the power supply voltage is doubled in the circuit shown in Figure 4, in order to obtain satisfactory hybrid operation, the sixth
By adding an impedance as shown in the figure and placing an impedance L2, which is an inductive impedance, in parallel with the series circuit of the capacitor C, which is a capacitive impedance, and the discharge lamp 1, L, one C-S and L -C-
In addition to suppressing the resonance vibration of 1, the impedance L
, and L2, the input voltage to the CS (or 1) circuit can be reduced in a voltage division manner.

As a result, the equivalent input voltage 0 voltage to the discharge lamp 1 becomes a desired value of about the lamp voltage. Figure 1 is equivalent to using a second inductance element and a discharge lamp as the impedance part used for voltage division and power factor correction, and the power supply voltage is about twice the lamp voltage. This is effective when turning on two lights at night. Also, ``The voltage of capacitor 3 in Fig. 1 is 1
Since the voltage and capacity are almost the same as when the lamp is lit, and the switching element 7 does not require a high starting voltage, an element having a withstand voltage of about the same level as when one lamp is lit is sufficient. There will be two inductance elements, but the capacitance (VA) of each will be approximately 1'2, so
Overall, it may be equivalent to the one in FIG. The voltage vectors at each part in Figure 1 are as shown in Figure 7, and the voltage vectors in Figure 5 are as shown in Figure 8. In Figure 1, the capacitor voltage Vc is low, and VL and (VL, It can be seen that there is not much difference in VL2). As described above, the present invention connects a first inductance element, a capacitor, and a first discharge lamp in series to a power supply, and connects the first inductance element, the capacitor, and the first discharge lamp in series.
Since a series circuit of a second inductance element and a second discharge lamp is connected in parallel to the series circuit of the discharge lamps, and a semiconductor switch element is connected in parallel to the first discharge lamp, the capacitor, It is possible to reduce the voltage applied to the semiconductor switching element, and it is small, lightweight, has low loss, and has the advantage of being able to provide flickerless lighting.

[Brief explanation of drawings]

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 is an operating waveform diagram of the same as above, and Fig. 4 is a conventional discharge lamp lighting circuit. Basic circuit diagram of the circuit,
Figure 6 is a basic circuit diagram for lighting the same two lamps as above, Figure 6 is a diagram explaining the principle of the present invention, Figure 7 is a voltage vector diagram of Figure 1, and Figure 8 is a voltage vector diagram of Figure 5. be. 1... Power supply, 2... First inductance element, 3
・・・・Cosodensa, 4...・First discharge lamp, 5...
. . . second inductance element, 6 . . . second discharge lamp, 7 . . . semiconductor switch element. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

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