JPH048915B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lighting device capable of lighting a plurality of discharge lamps having different rated lamp currents using an inverter circuit. It is generally known that two lamps with the same rating can be lit using one lighting device. In contrast, Japanese Patent Laid-Open No. 56-86495, shown in FIGS. 1 and 2, has been proposed as a device that can light two lamps with the same rated current even if the rated powers of the lamps are different. In FIGS. 1 and 2, reference numeral 1 denotes an AC power source, and a high frequency power conversion circuit having constant current characteristics, such as an inverter circuit 2, is connected to this AC power source 1. This inverter circuit 2 uses a push-pull type inverter, and consists of a full-wave rectifier circuit 3, a constant current inductor 4, a pair of transistors 51, 52, bias resistors 61, 62, a resonant capacitor 7, and an output transformer 8. . In this case, the inverter circuit 2 has a full-wave rectifier circuit 3 connected to the AC power supply 1, the positive terminal of the rectifier circuit 3 connected to the midpoint of the primary winding 81 of the output transformer 8, and a bias resistor 61. the base of the transistor 51 through the bias resistor 62, and the base of the transistor 52 through the bias resistor 62.
The negative terminal of the rectifier circuit 3 is connected to the emitters of transistors 51 and 52 via a constant current inductor 4, respectively. In addition, the collectors of transistors 51 and 52 are connected to the
The resonant capacitor 7 is connected to both ends of the primary winding 81 , and the resonant capacitor 7 is connected between the primary windings 81 . The output transformer 8 has a secondary winding 82 and a feedback winding 83 in addition to the primary winding 81, and the feedback winding 83 is connected to the bases of the transistors 51 and 52, respectively. On the other hand, in FIG. 1, a current balancing transformer 9 is connected to the output end of the inverter circuit 2, that is, one end of the secondary winding 82 of the output transformer 8. This transformer 9 consists of windings 91 and 92, and a connection point between these windings 91 and 92 is connected to one end of the secondary winding 82. In this case, these windings 91,
92 is set so that n1=n2 when the number of turns is n1 and n2, so that the currents flowing through the windings 91 and 92 are made equal, respectively. These windings 91 and 92 are connected to the other end of the secondary winding 82 via discharge lamps 101 and 102, respectively. In the lighting device configured as described above, when an AC voltage is applied to the rectifier circuit 3 from the AC power source 1, a DC output is generated from the rectifier circuit 3. As a result, in the inverter circuit 2, the above DC output is transferred to the bias resistors 61 and 62.
It is given as the base current of transistors 51 and 52 via. Then, transistors 51,5
2, one of them turns on first due to a slight imbalance, but if the transistor 51 turns on first, current flows through the primary winding 81 of the output transformer 8.
In this state, an oscillating voltage is generated by the inductance of the primary winding 81 and the resonant capacitor 7, which generates an electromotive force in the feedback winding 83, which in turn turns on the transistor 52. As a result, the transistors 51 and 52 are alternately turned on and off in the same manner, and a high frequency output is generated in the secondary winding 83 of the output transformer 8. This high frequency output is then given to the transformer 9, but if current I is now given to the transformer 9, a current of 1/2 I flows through each winding 91, 92 of the transformer 9, so the current at this time The discharge lamps 101 and 102 will be lit in parallel. In this case, the inverter circuit 2 changes the load characteristic to the fifth
It is known that, unlike the load characteristics of the conventional ballast obtained as shown in Figure a and shown in Figure b, there is a constant current characteristic region (hatched area in the figure).
This is due to the existence of a large leakage inductance of the output transformer 8. As a result, a constant current output is generated in the secondary winding 82 of the output transformer 8 in this constant current characteristic region.
Therefore, the currents flowing through the windings 91 and 92 of the transformer 9 are always equal in phase and kept constant, so if the discharge lamps 101 and 102 have the same rated lamp current, even if the rated lamp power is different, It is possible to stably light these in parallel. In other words, as an example, as shown in the table below.
Considering the FCL-32 and FCL-40 discharge lamps

[Table] Although the rated lamp power is different, the rated lamp current is the same, so if the output current of the inverter circuit 2 is designed in advance to be 0.97A, the discharge lamps 101 and 102 can be used as either 32W or 40W. Even if two types of lights are used, they can be stably lit in parallel. On the other hand, in FIG. 2, discharge lamps 101 and 10 are connected to the secondary winding 82 of the output transformer 8 of the inverter circuit 2.
2 series circuits are connected, and the switch 11 is connected in parallel to the discharge lamp 102. Other details are the same as in FIG. Even in this way, a constant current can be applied to the discharge lamps 101 and 102, so these discharge lamps 10
If lamps 1 and 102 have the same rated current, lamps with different rated powers can be lit in series in an appropriate combination. As described above, with this conventional device, two lamps can be lit by the same lighting device, even if the lamps have different rated power, if the rated lamp currents are the same. However, in such conventional devices, if the rated lamp currents are not equal, it is impossible to combine 40W and 30W fluorescent lamps, for example, and there are significant practical limitations. The present invention aims to eliminate the above-mentioned drawbacks, and proposes a device that can light a plurality of lamps with different rated currents using the same lighting device. FIG. 3 shows an embodiment of the device according to the invention,
In the figure, 1 is an AC power supply, 2 is an inverter circuit, and is configured in the same way as the device shown in FIG.
A high frequency voltage is generated in the next winding 82. 3 is a full-wave rectifier circuit, 9 is a current balancing transformer, 91, 92
are equal windings, 101 and 102 are lamps, and 11 is the current correction impedance of lamp 1.
01 is connected in parallel. In the apparatus configured as above, the lamp 102 is now compared with the 30W fluorescent lamp (rated current 0.62A) as the discharge lamp of the first group with the largest rated current, and the lamp 101 is the discharge lamp of the first group. Assume that a 40W fluorescent lamp (rated current 0.435A) is connected as a second group of discharge lamps with a smaller rated current. Although preheating of the electrodes of the lamps 101 and 102 is not illustrated here, if necessary, for example, a preheating winding may be provided in the output transformer 8 and preheating may be performed using this output. When trying to light up the lamps 101 and 102 using the output voltage of the secondary winding 82 of the output transformer 8 of the inverter circuit 2, since the inverter circuit 2 is generating output as in the device shown in FIG. 9 operates so that the currents in windings 91 and 92 are equal. The currents in these windings 91 and 92 are
If the output current of the inverter circuit 2 is set to 0.62A, the rated current flows through the 30W fluorescent lamp of the lamp 102. At this time, the current flowing through the winding 91 is connected to the current correction impedance 11 and the lamp 10.
1. Therefore, the current shunted to the current correction impedance 11, that is, the lamp 102
By taking into account the current corresponding to the difference in the rated current between the lamp 101 and the lamp 101, and setting the impedance value so that the rated current flows through the lamp 101, the rated current of 0.435A can also flow through the lamp 101. FIG. 4 shows another embodiment of the present invention, in which lamps 101 and 102 with different rated currents are lit in series, and a current correction impedance 11 is connected in parallel to the lamp 101 with the smaller rated current. This device is also similar to the device shown in FIG.
01 and 102 can be turned on by applying different currents to them. In addition, in conventional lighting devices that lit two lamps of the same type in series, there was one that connected a capacitor in parallel with one lamp, but this was done to ensure that the lamps would start. This device is for auxiliary use and is intended to cause a current of about several mA to several times that amount to flow through the lamp, and its principle and operation and effect are completely different from the device of the present invention. In the above embodiment, an inverter circuit having a leakage transformer is used as an output transformer, but other configurations may be used. In addition, the main current-limiting impedance of the output current of the inverter circuit 2 is leakage inductance, that is, inductive reactance in the embodiment. In some cases, it is preferable to use a capacitive reactance or capacitor as the current correction impedance 11. This is particularly good when the inverter circuit 2 is constituted by a self-oscillating inverter circuit having a resonant circuit, from the viewpoint of stability of the operating frequency. This is because when the inverter circuit 2 has a resonant circuit in FIG. 3 or 4, if the main current limiting impedance and current correction impedance are composed of different reactance components (for example, a coil and a capacitor), Resonance frequencies due to these different reactance components also exist, and in such a state, a resonant frequency component that is different from the original resonant frequency is likely to occur in the inverter's output frequency, resulting in distortion of the inverter's output voltage waveform. This is because, as a result, the operating frequency of the self-sustained oscillation may shift. Furthermore, although various configurations of the full-wave rectifier circuit 3 are not shown in the embodiments, any structure that can supply an appropriate DC voltage to be input to the inverter circuit 2 may be used. In addition, it is also possible to connect a dimmer or the like that performs phase control between the AC power source 1 and the full-wave rectifier circuit 3 to control the output of the inverter circuit 2. It is also possible to apply the device of the present invention to, for example, lighting three or more lamps. For example, if two 30W fluorescent lamps and two 40W fluorescent lamps are used as four lights using the device shown in Fig. 3, two 30W fluorescent lamps are connected in series and placed at the position of lamp 102. However, two 40W fluorescent lamps may be arranged in series at the position of the lamp 101. In addition, in the case of three lights, when two 30W fluorescent lamps and one 40W fluorescent lamp are used, if it is applied to the apparatus shown in FIG. 4, the 40W fluorescent lamp is placed at the position of lamp 101,
Two 30W fluorescent lamps may be arranged in series at the position of the lamp 102. In these cases, a starting auxiliary impedance may be further connected in parallel with the lamp, if necessary. In the above explanation, the case of a fluorescent lamp was explained, but the present invention may be applied to other discharge lamps, HID lamps, etc. As described above, according to the device of the present invention, when lighting a plurality of lamps with different rated currents with a lighting device including one inverter circuit, the rated current is compared with the first group of discharge lamps having a larger rated current. A current correction impedance set to an impedance value that shunts a current corresponding to the difference in rated current between the first group discharge lamp and the second group discharge lamp is connected in parallel to the second group discharge lamp, which has a smaller current. By doing so,
Except for restrictions when lighting two or more lamps,
This provides the effect of being able to obtain a variety of illumination.

[Brief explanation of drawings]

Figures 1 and 2 are circuit diagrams of conventional equipment, and Figure 3 is a circuit diagram of a conventional device.
4 are circuit diagrams showing different embodiments of the present invention, and FIG. 5 is an explanatory diagram of a conventional device. In the figure, 1 is an AC power supply, 2 is an inverter circuit, and 3
1 is a full-wave rectifier circuit, 9 is a current balancing transformer, 11 is a current correction impedance, and 101 and 102 are discharge lamps. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An inverter circuit that inputs AC power through a full-wave rectifier circuit, and a plurality of discharge lamps with different rated current values that are lit by the output current of the inverter circuit, A first group of discharge lamps having the highest rated current among the lamps and a second group of discharge lamps having a smaller rated current than the first group of discharge lamps are connected so that substantially equal inverter circuit output currents are supplied to each of them. In the discharge lamp lighting device, when lighting the discharge lamps of the first group and the second group, a current corresponding to a difference in rated current between the discharge lamps of the first group and the discharge lamps of the second group is shunted. A discharge lamp lighting device characterized in that a current correction impedance set to an impedance value is connected in parallel to a second group of discharge lamps. 2. The discharge lamp lighting device according to claim 1, wherein the first group of discharge lamps and the second group of discharge lamps are connected in series to an output end of an inverter circuit. 3. The discharge lamp lighting device according to claim 1, characterized in that the first group of discharge lamps and the second group of discharge lamps are connected in parallel to the output end of an inverter circuit via a current balancing transformer. . 4. In an inverter circuit that includes a resonant circuit and performs self-excited oscillation operation, the reactance component of the current correction impedance is of the same type as the reactance component of the current-limiting impedance of the main output current of the inverter circuit. A discharge lamp lighting device according to any one of claims 1 to 3.