JPH10108479A - Constant-curent push-pull inverter, discharging lamp lighting equipment, and lighting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have good constant-current characteristics and good current superimposition characteristics and hardly have abnormal oscillation by installing a first inductor with a closed magnetic path and a second inductor with a closed magnetic path in series between a pair of transistors and a source of DC. SOLUTION: The collectors of transistors 2a, 2b are connected to the ends of a primary winding of an output transformer 1 respectively and the positive pole of a DC power supply 3 is connected to one end of a first inductor 4 and the negative pole is connected to one end of a second inductor 5. The first inductor 4 is provided with a relatively large inductance with an iron core having a closed magnetic path and the second inductor 5 is provided with a relative small inductance with an iron core having a cosed magnetic path. Owing to this structure, the first inductor 4 mainly distributes to the action to make the current constant and the second inductor 5 has good DC superimposition characteristics and therefore there is no abnormal oscillation even when instantaneous large current is caused to flow at the time of start up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a constant current push-pull inverter, a discharge lamp lighting device, and a lighting device.

[0002]

2. Description of the Related Art A constant current push-pull inverter has been conventionally used as a power supply for various electric appliances including a discharge lamp lighting device.
No. 5-77378.

FIG. 6 is a circuit diagram of a conventional constant current push-pull inverter.

In the figure, reference numeral 61 denotes an output transformer, 62
a and 62b are a pair of transistors, 63 is a DC power supply, 6
4 is an inductor, 65 is an AC power supply, and 66 is a discharge lamp of a load.

The output transformer 61 includes a primary winding 61 _P ,
A primary winding 51 includes a primary winding 61 _S and a tertiary winding 61 _T.
The middle point of _P is connected to the positive electrode of DC power supply 63.

[0006] transistors 62a, 62b are respectively connected to collectors to both ends of the primary winding 61 _P, are connected by connecting the emitter to each other at one end of the inductor 64 for a constant current. The base is the tertiary winding 61 of the output transformer 61
Connected to _T to form a control circuit.

The other end of the inductor 64 is connected to the DC power source 6.
3 is connected to the negative electrode.

[0008] Then, the transistors 62a, 62b is to obtain an AC output across the secondary winding 61 _S ends of the output transformer 51 are alternately turned on, by turning off.

[0009]

If the inductance of the constant current push-pull inverter does not exceed a certain value, the switching waveform becomes worse and the constant current push-pull inverter does not become constant current.

Therefore, in order to increase the inductance value to a predetermined value or more, it is necessary to provide a closed magnetic circuit with a core structure.

However, when a closed magnetic circuit structure is used, the DC superimposition characteristic deteriorates. Therefore, when a large current flows for a moment such as at the time of starting, there is a problem that the inductor is saturated and the inverter oscillates abnormally.

The present invention is directed to a constant current push-pull inverter, which has improved constant current inductors, has good constant current characteristics, good DC superposition characteristics, and is unlikely to cause abnormal oscillation, and a discharge lamp using the same. It is an object to provide a lighting device and a lighting device.

[0013]

A constant current push-pull inverter according to the present invention is connected in parallel to an output transformer via a primary winding of the output transformer and via the primary winding. And a second inductor having a closed magnetic circuit and an open magnetic circuit arranged in series between the pair of transistors and the DC power supply. And an inductor.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

The output transformer may have at least a primary winding. The primary winding mainly functions to switch the DC voltage. However, if necessary, an AC output stepped down from the DC power supply voltage may be obtained from a part of the primary winding. The boosted AC output may be obtained by extending the next winding. All of these outputs are electrically non-insulated. If necessary, a secondary winding which is conductively insulated from the primary winding can be provided, and an AC output can be extracted therefrom. This method of taking out is electrically insulated. Further, when the inverter is a self-excited type, a tertiary winding can be provided in the output transformer.
In the case of the separately-excited type, the tertiary winding in the above sense is unnecessary.

The transistor may be any type such as a bipolar transistor or a field effect transistor called FET. Connecting in parallel means not only that the primary winding of the output transformer intervenes in the parallel circuit,
If the basic operation of the push-pull inverter is not lost even if other circuit components are interposed, such a circuit means that the circuits are in parallel as referred to in the present invention.

The DC power supply may be any type such as a battery and a rectified power supply.

The inductor is interposed in series between the DC power supply and a pair of transistors connected in parallel via the primary winding of the output transformer to make the current flowing into the inverter constant. However, in the present invention, the first inductor includes a closed magnetic circuit, and the second inductor includes an open magnetic circuit. Since the first inductor has a closed magnetic circuit, the inductance can be set to a required large value. Since the second inductor has an open magnetic circuit, the inductance is small, but the DC bias characteristics are good. Both inductors need only be interposed in series between the DC power supply and a pair of transistors connected in parallel, so that one is separated and connected to the positive side of the DC power supply and the other is connected to the negative side. Or both may be connected in series on either pole side.

Thus, in the present invention, since the first inductor is provided with a closed magnetic circuit, the inductance is increased to ensure constant current characteristics, and the second inductor has a closed magnetic circuit configuration. Even though the inductance is small, the DC superimposition characteristics are good. Therefore, even when a large current flows instantaneously at the time of starting or the like, the second inductor does not saturate, so that abnormal oscillation does not occur.

A constant current push-pull inverter according to a second aspect of the present invention is connected in parallel to an output transformer via a primary winding of the output transformer and to a DC power supply via the primary winding. A first inductor having a relatively large inductance and a second inductor having a relatively small inductance arranged in series between the pair of transistors and the DC power supply; It is characterized by having.

In the present invention, since the first inductor has a large inductance, it can be easily realized by providing a core having a closed magnetic circuit structure. Since the second inductor has a small inductance, it can be easily realized by providing an iron core having an open magnetic circuit structure.

Therefore, it is possible to operate as in claim 1.

A constant current push-pull inverter according to a third aspect of the present invention is the constant current push-pull inverter according to the first or second aspect, wherein the first inductor is connected to the positive electrode of the DC power supply; It is connected to the negative side of the DC power supply;

In the present invention, since the first inductor having a large or large inductance is connected to the positive electrode side of the DC power supply, no high-frequency component is superimposed on the DC power supply side. Abnormal oscillation of the control circuit does not occur. Even if the second inductor is connected to the negative electrode side of the DC power supply, the second inductor is still interposed between the DC power supply and the inverter with respect to the inverter. Since the inductor is less likely to be magnetically saturated, abnormal oscillation of the inverter can be reduced.

According to a fourth aspect of the present invention, there is provided a constant current push-pull inverter according to the first or second aspect, wherein the first and second inductors are:
Both are characterized in that they are connected to the positive electrode side of the DC power supply.

In the present invention as well, the second inductor prevents abnormal saturation of the inverter by making it difficult for the second inductor to be magnetically saturated even with an instantaneous large current.

According to a fifth aspect of the present invention, there is provided a constant current push-pull inverter according to any one of the first to fourth aspects, wherein the output transformer has at least a primary winding and a secondary for supplying power to a load. It is characterized in that it has a self-excited structure including a winding and a tertiary winding connected to a control circuit of the transistor.

Since the present invention is a self-excited constant current push-pull inverter, the circuit configuration can be simple and inexpensive. Further, the load can be electrically insulated from the power supply.

A constant current push-pull inverter according to a sixth aspect of the present invention is the constant current push-pull inverter according to any one of the first to fifth aspects, wherein the constant current push-pull inverter is provided with an oscillating circuit for alternately switching transistors and is a separately excited type. It is characterized by being constituted.

The present invention relates to a separately excited constant current push-pull inverter, which is a stable operation inverter. As the oscillation circuit, various known circuits for this kind of application can be used.

According to a seventh aspect of the present invention, there is provided a constant current push-pull inverter according to any one of the first to sixth aspects, further comprising a DC power supply.

Since the present invention has a DC power supply as a part of the configuration of the constant current push-pull inverter, it can be used by directly connecting to an AC power supply. It is particularly advantageous when the discharge lamp is used as a main component of a discharge lamp lighting device for high frequency lighting.

[0033] The discharge lamp lighting device according to claim 8 is:
A constant current push-pull inverter according to any one of claims 1 to 7 is provided.

In the present invention, in order to feed a discharge lamp from a constant current push-pull inverter for lighting, an impedance for stabilizing the discharge is required. As means for applying this impedance, the output of an output transformer of the inverter is used. A leakage impedance is provided to the secondary winding by forming a leakage magnetic path in a winding, for example, an iron core of the secondary winding, or a choke coil or the like separate from an output transformer between the output winding and the discharge lamp. Inductors may be connected in series. The impedance may be a capacitive impedance or a resistance in addition to the inductive impedance.

A discharge lamp lighting device according to a ninth aspect of the present invention is
A constant current push-pull inverter according to any one of claims 1 to 7, and a discharge lamp receiving power supply from the constant current push-pull inverter.

The discharge lamp lighting device of the present invention has a discharge lamp as one of its components. The discharge lamp is applicable to various discharge lamps such as a fluorescent lamp, a high-intensity discharge lamp such as a mercury lamp, a metal halide lamp, and a high-pressure sodium lamp.

According to a tenth aspect of the present invention, there is provided a lighting device, comprising: a lighting device main body; and a discharge lamp lighting device according to the ninth aspect, which is disposed in the lighting device main body.

The illuminating device of the present invention is applicable to various luminaires for indoor and outdoor use, display devices such as liquid crystal backlights, and instrument display devices, that is, devices using all kinds of light, that is, illuminating devices.

[0039]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of a constant current push-pull inverter and a discharge lamp lighting device according to the present invention.

In the figure, 1 is an output transformer, 2a, 2
b is a transistor, 3 is a DC power supply, 4 is a first inductor, 5 is a second inductor, 6 is a discharge lamp, and 7 is a resonance capacitor.

The output transformer 1 has a primary winding 1 _P , a secondary winding 1 _S and a tertiary winding 1 _T.

The transistors 2a, 2b has a collector connected to both ends of the primary winding 1 _P of the output transformer 1, and an emitter connected to one another.

The DC power supply 3 has a positive electrode connected to one end of the first inductor 4 and a negative electrode connected to one end of the second inductor 5.

The first inductor 4 has a relatively large inductance provided with a core of a closed magnetic circuit. The other end is connected to the middle point of the primary winding 1 _P of the output transformer 1.

The second inductor 5 has a relatively small inductance with an iron core of an open magnetic circuit. The other ends are connected to the emitters of the transistors 2a and 2b, respectively.

As the discharge lamp 6, a metal halide lamp is used in this embodiment. In order to stabilize the discharge of the discharge lamp, an appropriate inductance is given to the secondary winding 1 _S of the output transformer 1 by a leakage magnetic path provided in an iron core.

The resonance capacitor 7 is connected in parallel with the primary winding 1 _P to form a resonance circuit.

The base of the one transistor 2a is connected to one end of the tertiary winding 1 _T of the output transformer 1, the base of the other transistor 2b is connected to the other end of the tertiary winding 1 _T, respectively A base circuit of the transistors 2a and 2b, that is, a control circuit is formed. A starting circuit is formed at the base of each of the transistors 2a and 2b by being connected to the positive electrode of a DC power supply via a starting resistor 8.

When the DC power supply 3 is turned on, the transistors 2a and 2b are biased via the starting resistor 8. Then, one transistor, for example, 2a is turned on by a slight imbalance of the circuit. Transistor 2
By turning on a, the current flows in the order of the positive electrode of the DC power supply 3 → the first inductor 4 → the upper half of the primary winding 1 _P → the collector / emitter of the transistor 2 a → the second inductor 5 → the negative electrode of the DC power supply 3. Begins to flow. Due to the flow of this current,
An electromotive force is generated in the primary winding 1 _P and resonance occurs with the resonance capacitor 7. In addition, voltage is induced in the tertiary winding 1 _T,
This voltage forward biases transistor 2a and reverse biases transistor 2b. As a result, transistor 2
a turns on sufficiently, and the transistor 1b turns off completely. Although the windings of each half which are separated by the midpoint of the primary winding 1 _P resonance voltage of the sine wave is generated by the resonance, the resonance voltage is inverted to the negative direction, third coils 1 _T of the induced voltage , The transistor 2a is turned off and the transistor 2b is turned on. As a result, the current flowing from the DC power supply 3 becomes the positive electrode of the DC power supply 3 → the first inductor 4 →
The collector of the primary winding 1 _P under half → transistor 2b ·
The current starts to flow in the order of the emitter → the second inductor 5 → the negative electrode of the DC power supply 3. The flow of this current, induced voltage of the tertiary winding 1 _T will reverse bias the transistor 2a, forward biasing the transistor 2b. As a result, the transistor 2a is completely turned off, and the transistor 2b is sufficiently turned on. The inverter operates by repeating the above operation.

Then, the first and second inductors 4,
5 makes the input current of the inverter constant, and thus makes the load current constant, and stabilizes the oscillation operation of the inverter. With the operation of the constant current push-pull inverter, the discharge lamp 6 of the load starts discharging and lights up.

In the present embodiment, the first inductor 4 has an iron core having a closed magnetic circuit structure and has a relatively large inductance, and thus mainly contributes to a constant current operation. On the other hand, the second inductor 5
Has an iron core with an open magnetic circuit structure and relatively low inductance, so it does not contribute much to the constant current operation.
For example, even when an instantaneous large current flows at the time of startup, the core does not saturate, so that abnormal oscillation does not occur.

In this embodiment, the DC power supply 3
Since the first and second inductors 4 and 5 are separately connected to the positive and negative electrodes of the inverter, the superposition of high frequency noise from the inverter side to the power supply side is more effectively prevented.

FIG. 2 is a circuit diagram showing a second embodiment of the constant current push-pull inverter according to the present invention.

In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 9 denotes an inverter body having the same configuration as that of FIG.

In the present embodiment, the first inductor 4 is connected to the negative side of the DC power supply 3, and the second inductor 5 is connected to the positive side.

The operation and effect of this embodiment are also essentially the same as those of FIG. However, in terms of preventing the leakage of the high frequency noise to the DC power supply side, the performance is low, though slightly, as compared with that of FIG.

FIG. 3 is a circuit diagram showing a third embodiment of the constant current push-pull inverter according to the present invention.

In the figure, the same parts as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

In the present embodiment, the second inductor 5 is connected in series with the first inductor 4 on the positive side of the DC power supply 3.

The operation and effect of this embodiment are also essentially the same as those of FIG. However, it does not prevent noise flowing out from the negative electrode side to the DC power supply 3, but there is substantially no problem since the outflow to the negative electrode side is very small.

FIG. 4 is a circuit diagram showing a fourth embodiment of the constant current push-pull inverter according to the present invention and a second embodiment of the discharge lamp lighting device.

The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

This embodiment is a separately excited type constant current push-pull inverter, and is a discharge lamp lighting device in which the discharge lamp 6 is a fluorescent lamp.

In the figure, reference numeral 10 denotes an oscillator,
To generate a control signal for alternately turning on and off the transistors 2a and 2b. Further, 1 _T is a tertiary winding provided in the output transformer 1 for heating the filament electrode 6 a of the discharge lamp 6. 11 is an inductor of the discharge stability, which are inserted in series between the discharge lamp 6 and the secondary winding 1 _S. The resonance capacitor 7 is connected in parallel with the secondary winding 1 _S , but is electrically the same as in FIG.

The DC power supply 3 is composed of a rectifier circuit 3a for rectifying the AC voltage of the AC power supply 12, and a smoothing capacitor 3b for smoothing the rectified pulsating flow. Reference numeral 13 denotes a noise prevention capacitor.

Although the present embodiment is of the separately excited type, the operation of the first and second inductors is exactly the same as that of the self-excited type, and the DC superimposition characteristics when a momentary large current flows through the second inductor are good. It is.

FIG. 5 is a front view of a lighting fixture showing one embodiment of the lighting device of the present invention.

In the figure, reference numeral 14 denotes a lighting fixture main body, and reference numeral 15 denotes a lighting device having the circuit configuration shown in FIG. 1 or FIG. The discharge lamp 6 is a fluorescent lamp, and is mounted on a pair of sockets 14a, 14a arranged near both ends of the lighting fixture body 14.

[0070]

According to the first to seventh aspects of the present invention, the constant current inductor interposed in series between the DC power supply and the transistor can have the required inductance mainly by the first inductor. It is possible to provide a constant current push-pull inverter that has good constant current characteristics and also has good DC superimposition characteristics due to the second inductor and is unlikely to cause abnormal oscillation.

According to the second aspect of the present invention, in addition, since the first inductor can be configured as a closed magnetic circuit and a required inductance can be imparted, the constant current characteristics are good, and the second inductor is an open magnetic circuit. Therefore, since it is difficult to saturate, it is possible to provide a constant current push-pull inverter having good DC superimposition characteristics.

According to the third aspect of the present invention, in addition, since the first inductor is connected on the positive electrode side of the DC power supply, a constant current push-pull inverter in which high frequency noise hardly leaks to the DC power supply side is provided. Can be.

According to the fourth aspect of the present invention, in addition, since both the first and second inductors are connected to the positive side of the DC power supply, it is possible to provide a constant current push-pull inverter in which the wiring of the inductors is easy. it can.

According to the invention of claim 5, in addition, a self-excited constant current push-pull inverter can be provided.

According to the invention of claim 6, it is possible to provide a separately excited constant current push-pull inverter.

According to the invention of claim 7, it is possible to provide a constant current push-pull inverter having a DC power supply.

According to the eighth and ninth aspects of the invention, it is possible to provide a discharge lamp lighting device having the effects of the first to seventh aspects.

According to the ninth aspect of the present invention, it is possible to provide a discharge lamp lighting device including a discharge lamp as a component.

According to the tenth aspect, it is possible to provide a lighting device having the effects of the first to seventh aspects.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a constant current push-pull inverter and a discharge lamp lighting device of the present invention.

FIG. 2 shows a second embodiment of the constant current push-pull inverter according to the present invention.
Circuit diagram showing an embodiment of the present invention.

FIG. 3 shows a third embodiment of the constant current push-pull inverter according to the present invention.
Circuit diagram showing an embodiment of the present invention.

FIG. 4 shows a fourth embodiment of the constant current push-pull inverter according to the present invention.
Circuit diagram showing an embodiment of the present invention and a second embodiment of the discharge lamp lighting device

FIG. 5 is a front view showing an embodiment of the lighting device of the present invention.

FIG. 6 is a circuit diagram of a conventional constant current push-pull inverter.

[Explanation of symbols]

1 ... Output transformer 1 _P ... 1 winding 1 _S ... 2 winding 1 _T ... 3 winding 2a, 2b ... transistor 3 ... DC power supply 4 ... first inductor 5 ... second inductor 6 ... discharge lamp

Claims (10)

[Claims] A pair of transistors connected in parallel via a primary winding of the output transformer and connected to a DC power supply via a middle point of the primary winding; A first inductor having a closed magnetic circuit arranged in series between a pair of transistors and a DC power supply, and a second inductor having an open magnetic circuit. Current push-pull inverter. A pair of transistors connected in parallel via a primary winding of the output transformer and connected to a DC power supply via a midpoint of the primary winding. A first inductor having a relatively large inductance and a second inductor having a relatively small inductance arranged in series between a pair of transistors and a DC power supply. Constant current push-pull inverter. 3. The constant current pusher according to claim 1, wherein the first inductor is connected to a positive side of the DC power supply; and the second inductor is connected to a negative side of the DC power supply. Pull inverter. 4. The power supply according to claim 1, wherein the first and second inductors are both connected to the positive side of the DC power supply.
Or the constant current push-pull inverter according to 2. 5. An output transformer comprising at least a primary winding, a secondary winding for supplying power to a load, and a tertiary winding connected to a control circuit of a transistor, and is configured to be self-excited. The constant current push-pull inverter according to any one of claims 1 to 4, wherein 6. The constant current push-pull inverter according to claim 1, further comprising an oscillating circuit for alternately switching the transistors, and configured as a separately excited type. 7. The constant current push-pull inverter according to claim 1, further comprising a DC power supply. 8. A discharge lamp lighting device comprising the constant current push-pull inverter according to claim 1. 9. A discharge lamp comprising: a constant current push-pull inverter according to claim 1; and a discharge lamp receiving power supply from the constant current push-pull inverter. Lighting device. 10. A lighting device comprising: a lighting device main body; and the discharge lamp lighting device according to claim 9 disposed in the lighting device main body.